{"gene":"SIX3","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":1995,"finding":"Six3 is a murine homologue of the Drosophila sine oculis gene, encoding a homeodomain-containing transcription factor expressed in the anterior neural plate and developing eye; its expression is not affected by Pax6 loss-of-function (Small eye mutants), placing it in a parallel or independent pathway.","method":"Gene cloning, sequence analysis, chromosomal mapping, in situ hybridization in wild-type and Pax6 mutant embryos","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — foundational characterization paper, >500 citations, multiple orthogonal methods","pmids":["8575305"],"is_preprint":false},{"year":1996,"finding":"Ectopic expression of mouse Six3 in medaka fish embryos is sufficient to promote ectopic lens formation, demonstrating that Six3 can trigger the genetic pathway leading to lens differentiation independently of retinal tissue.","method":"Ectopic RNA injection/overexpression in medaka fish embryos with histological and molecular marker analysis","journal":"Mechanisms of development","confidence":"High","confidence_rationale":"Tier 2 — direct gain-of-function with defined cellular phenotype, >100 citations","pmids":["9025075"],"is_preprint":false},{"year":1999,"finding":"Mutations in the homeodomain of human SIX3 cause holoprosencephaly; at least four different homeodomain mutations are associated with HPE2 and are predicted to interfere with transcriptional activation, establishing SIX3 as the HPE2 gene.","method":"Positional cloning, mutational analysis in HPE patients, chromosomal mapping of translocation breakpoints","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 — human genetics with multiple independent mutations, >290 citations","pmids":["10369266"],"is_preprint":false},{"year":1999,"finding":"Six3 overexpression in medaka fish embryos causes ectopic Pax6 and Rx2 expression in midbrain and cerebellum, leading to formation of ectopic retinal primordia; injected mouse Six3 also initiates ectopic endogenous medaka Six3 expression, revealing an autoregulatory feedback loop.","method":"RNA injection/overexpression in medaka fish embryos with molecular marker analysis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — gain-of-function with defined molecular and cellular phenotypes, >180 citations","pmids":["10090721"],"is_preprint":false},{"year":2001,"finding":"Six3 functions as a Groucho-dependent transcriptional repressor in eye and forebrain formation; it contains eh1-related motifs that mediate interaction with the Groucho corepressor Grg3; point mutations in the eh1 motifs reduce both forebrain-enlarging activities and interaction with Grg3 in zebrafish.","method":"Yeast two-hybrid, dominant activator/repressor overexpression in zebrafish, site-directed mutagenesis, in vivo phenotypic analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including mutagenesis and in vivo rescue, >140 citations","pmids":["11401394"],"is_preprint":false},{"year":2001,"finding":"Six3 acts as a transcriptional repressor of the gamma-crystallin (CRYGF) promoter, reducing its activity to ~10% of basal, and acts antagonistically to Prox1 activator at the CRYGD/e/f promoters; a Six3-responsive element was mapped between -101 and -123 of the gammaF-crystallin promoter.","method":"Cell transfection reporter assays, randomly mutated promoter fragment analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — functional reporter assays with defined binding element, single lab","pmids":["11139622"],"is_preprint":false},{"year":2002,"finding":"Six3 interacts with Groucho-related corepressors Grg4 and Grg5 via a conserved phenylalanine in an eh1-like motif in the Six domain of Six3; this interaction was validated by co-immunoprecipitation; Six3 binds a specific DNA motif and acts as a potent transcriptional repressor through this interaction; disruption of the Groucho interaction abolishes Six3-dependent auto-repression and eye/lens developmental functions in vivo.","method":"Co-immunoprecipitation from cell lines, DNA-binding PCR assay, in vivo retroviral overexpression in rat retina, in ovo electroporation in chick, site-directed mutagenesis","journal":"Development","confidence":"High","confidence_rationale":"Tier 1–2 — reciprocal Co-IP, mutagenesis, in vivo functional validation with multiple species, >170 citations","pmids":["12050133"],"is_preprint":false},{"year":2002,"finding":"Six3 and Pax6 mutually activate each other's expression in the developing lens; Six3 binds regulatory sequences of the Pax6 gene and Pax6 binds regulatory sequences of Six3; lens-specific expression of Six3 rescues the Pax6 haploinsufficient lens phenotype via cell proliferation and activation of the PDGF-alpha-R/cyclin D1 signaling pathway.","method":"In vitro binding assays, transgenic rescue experiments, pathway analysis","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro binding + transgenic rescue + pathway analysis, multiple orthogonal methods","pmids":["12072567"],"is_preprint":false},{"year":2003,"finding":"Six3 is a direct negative regulator of Wnt1 expression in the anterior neuroectoderm; in Six3-null mice, Wnt1 expression is rostrally expanded; Six3 binds the Wnt1 locus in vivo and in vitro DNA-binding assays; ectopic Six3 in chick and fish embryos represses Wnt1; phenotypic rescue of headless/tcf3 zebrafish by mouse Six3 demonstrates Six3 acts upstream of Wnt signaling to specify forebrain fate.","method":"Six3 knockout mouse analysis, in vivo and in vitro DNA-binding assays, ectopic expression in chick and zebrafish, genetic epistasis (headless/tcf3 rescue)","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 — KO phenotype + direct DNA binding + genetic epistasis in multiple model systems, >380 citations","pmids":["12569128"],"is_preprint":false},{"year":2003,"finding":"The Six domain of Six3 (and Six6) strongly interacts with the QD domain of TLE1 and AES (Groucho family members); Six3 additionally interacts with TLE proteins via the WDR domain; gain-of-function in medaka shows synergistic activity between Six3/Six6 and TLE1 in expanding the eye field; AES abrogates Six3/Six6 overexpression phenotypes.","method":"Yeast two-hybrid screen, biochemical and mutational analysis, gain-of-function in medaka fish","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — Y2H plus biochemical domain mapping plus in vivo functional synergy, >110 citations","pmids":["12441302"],"is_preprint":false},{"year":2004,"finding":"Six3 directly binds to geminin (a DNA replication-inhibitor/Cdt1 sequestrator) and competes with Cdt1 for geminin binding, thereby promoting cell proliferation without transcription; overexpression of geminin in medaka phenocopies Six3 inactivation (forebrain/eye defects), and these defects are rescued by Six3; loss of geminin promotes retinal precursor proliferation, potentiating Six3 gain-of-function.","method":"Yeast two-hybrid screen, direct protein binding competition assay, overexpression and loss-of-function in medaka fish, genetic rescue experiments","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1–2 — Y2H + biochemical competition assay + genetic rescue in vivo, >200 citations","pmids":["14973488"],"is_preprint":false},{"year":2005,"finding":"Six3 expands the anterior neural plate partly through transcriptional regulation of cell cycle regulators cyclinD1 and p27Xic1 and anti-neurogenic genes Zic2 and Xhairy2; it can also expand the neural plate independently of the cell cycle by repressing Bmp4 expression in adjacent ectoderm; Six3 cannot alone induce neural tissue in animal caps but can do so in combination with Otx2.","method":"Ectopic expression in Xenopus and zebrafish, cell cycle inhibitor treatment, Bmp4 expression analysis, chordino mutant rescue","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — multiple in vivo gain-of-function and genetic epistasis experiments across two model organisms","pmids":["15843413"],"is_preprint":false},{"year":2005,"finding":"Lhx2 mediates an alternative/parallel pathway for cellular proliferation in the developing forebrain downstream of Six3; head-specific activation of Lhx2 completely rescues the telencephalon size reduction in six3 morphant zebrafish, whereas ectopic Six3b cannot rescue lhx2 knockdown, placing Lhx2 downstream of Six3 in this pathway.","method":"Antisense morpholino knockdown, caged-mRNA photoactivation in zebrafish, genetic epistasis","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with clean KD/OE and defined phenotypic readout, single lab","pmids":["16226737"],"is_preprint":false},{"year":2006,"finding":"Six3 directly activates Pax6 and Sox2 expression in the presumptive lens ectoderm; conditional deletion of Six3 in the lens ectoderm causes loss of Pax6 and Sox2 expression and failure of lens induction; ChIP, EMSA, and luciferase reporter assays confirm direct binding and activation; misexpression in chick promotes ectopic ectodermal Pax6 expression domain.","method":"Conditional knockout in mouse, ChIP, electrophoretic mobility shift assay (EMSA), luciferase reporter assay, chick misexpression","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — conditional KO + ChIP + EMSA + reporter assay + in vivo misexpression, multiple orthogonal methods","pmids":["17066077"],"is_preprint":false},{"year":2007,"finding":"MTA1 physically interacts with Six3 chromatin in a histone deacetylase-dependent manner, leading to transcriptional suppression of the Six3 gene; MTA1 is also a Six3-interacting corepressor contributing to self-negative regulation of Six3; Six3's homeodomain interacts with specific DNA elements in the rhodopsin promoter to stimulate rhodopsin transcription; Six3 cooperates with Crx or NRL in stimulating rhodopsin-luc transcription; HPE-associated Six3 homeodomain deletion mutations cannot bind rhodopsin DNA or stimulate its transcription.","method":"ChIP, Co-IP, gain/loss-of-function in MTA1-null mice and retinal ganglion cells, luciferase reporter assays","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1–2 — ChIP + Co-IP + in vivo KO + reporter assays with mutagenesis validation","pmids":["17666527"],"is_preprint":false},{"year":2007,"finding":"Six3 represses Wnt1 transcription; in Six3-null mice, Wnt1 is anteriorly expanded causing progressive caudalization of the diencephalon; analysis of Six3;Wnt1 double-null mice demonstrates that Six3-mediated repression of Wnt1 is necessary for formation of the rostral diencephalon, and that Six3 activity is required for telencephalon formation.","method":"Six3 knockout, Six3;Wnt1 double knockout genetic epistasis, developmental staging analysis","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — double KO genetic epistasis with defined molecular phenotype","pmids":["18094027"],"is_preprint":false},{"year":2007,"finding":"Six3 acts in the neuroectoderm to establish a prepattern of bilateral repression of Nodal activity in the dorsal diencephalon; reduction of Six3 function causes brain-specific deregulation of Nodal pathway activity resulting in epithalamic laterality defects; epistasis experiments position Six3 upstream of Nodal signaling in establishing brain left-right asymmetry.","method":"Zebrafish loss-of-function (morpholino), misexpression, genetic epistasis experiments","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — morpholino KD + misexpression + genetic epistasis, defined molecular pathway","pmids":["17678854"],"is_preprint":false},{"year":2008,"finding":"Six3 directly binds and activates the Shh brain enhancer-2 (SBE2), a remote forebrain enhancer located 460 kb upstream of SHH; HPE-causing SIX3 alterations fail to bind and activate SBE2; identified via DNA affinity-capture assay screening of SBE2 sequence.","method":"DNA affinity-capture assay, transgenic mouse enhancer assay, direct DNA-binding assay with HPE mutant proteins","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 1–2 — DNA affinity capture + transgenic enhancer validation + mutagenesis, >140 citations","pmids":["18836447"],"is_preprint":false},{"year":2008,"finding":"Six3 haploinsufficiency (deletion of one Six3 allele or replacement with HPE-associated mutant alleles) is sufficient to recapitulate human HPE in mice; Shh is a direct target of Six3 in the rostral diencephalon ventral midline (RDVM); reduced Six3 fails to activate Shh in the RDVM, demonstrating a direct regulatory relationship and a crossregulatory loop between Shh and Six3 in the ventral forebrain.","method":"Six3 haploinsufficiency mouse models, ChIP for Six3 binding to Shh locus, zebrafish functional assays","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1–2 — mouse genetic model + ChIP + zebrafish assay, multiple orthogonal methods, >130 citations","pmids":["18694563"],"is_preprint":false},{"year":2008,"finding":"HPE-associated SIX3 mutations are loss-of-function alleles (89% confirmed in zebrafish assays); disease-associated mutations in the Groucho-binding eh1-like motif decrease Six3 function in all assays, confirming that Six3-Groucho co-repressor interaction is essential for human SIX3 activity and HPE pathogenesis; truncated Six3 versions lacking the homeodomain retain partial function.","method":"Zebrafish gain-of-function and loss-of-function assays for 46 distinct SIX3 mutations, structure-function analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — systematic functional analysis of 46 mutations with multiple assay readouts","pmids":["18791198"],"is_preprint":false},{"year":2010,"finding":"Six3 directly represses Wnt8b expression in the developing neuroretina; conditional deletion of Six3 causes ectopic Wnt8b expression which is sufficient to suppress neuroretina specification; ChIP identified Six3-responsive elements in the Wnt8b locus; transgenic ectopic Wnt8b expression phenocopies Six3 deletion in blocking neuroretina specification.","method":"Conditional Six3 knockout in mouse, ChIP, transgenic Wnt8b overexpression, comparative molecular analysis","journal":"Journal of Clinical Investigation","confidence":"High","confidence_rationale":"Tier 1–2 — conditional KO + ChIP + transgenic phenocopy, multiple orthogonal methods","pmids":["20890044"],"is_preprint":false},{"year":2010,"finding":"MTA1s and MTA1 physically interact with Six3 chromatin and inhibit Six3 transcription in a histone deacetylase-dependent manner; this allows derepression of Wnt1 transcription (which Six3 normally represses); in MTA1/MTA1s null cells, Six3 is upregulated and Six3 corepressor complex recruitment to the Wnt1 promoter is increased.","method":"ChIP, gain/loss-of-function (knockdown and knockout), multiple model systems including MEFs and mammary glands","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1–2 — ChIP + KO model + multiple cell systems","pmids":["20682799"],"is_preprint":false},{"year":2011,"finding":"Six3OS, a long noncoding RNA transcribed from the distal promoter region of Six3, binds directly to Ezh2 and Eya family members, acting as a molecular scaffold to recruit histone modification enzymes to Six3 target genes, thereby modulating Six3 activity during retinal cell specification without affecting Six3 expression levels.","method":"Overexpression and knockdown analysis, direct binding assays (Six3OS-Ezh2 and Six3OS-Eya interactions), retinal cell specification assays","journal":"Neural development","confidence":"High","confidence_rationale":"Tier 2 — direct binding + functional loss/gain-of-function + mechanistic scaffold characterization","pmids":["21936910"],"is_preprint":false},{"year":2011,"finding":"Six3 is required for ependymal cell maturation; in its absence, ependymal cells fail to suppress radial glia characteristics, resulting in defective lateral wall, abnormal neuroblast migration and differentiation, and hydrocephaly; Six3 is expressed in ependymal cells during formation of the lateral wall of the lateral ventricles.","method":"Six3 conditional knockout in mouse, cellular marker analysis, localization studies","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — conditional KO with specific cellular and tissue-level phenotypic readouts","pmids":["22071110"],"is_preprint":false},{"year":2012,"finding":"Six3 promotes ventral telencephalic fates by transiently regulating foxg1a expression and repressing the Wnt/β-catenin pathway; Six3 cooperates with Hedgehog signaling to specify ventral telencephalon, with an Hh-independent role in isl1-positive (but not nkx2.1b-positive) cells.","method":"Zebrafish six3b;six7 double morphant analysis, genetic epistasis with Hedgehog pathway, overexpression experiments","journal":"Development","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis and KD in zebrafish, single lab","pmids":["22736245"],"is_preprint":false},{"year":2013,"finding":"Sox2 directly regulates a long-range forebrain enhancer to activate Six3 expression in the rostral diencephalon; biochemical (ChIP) and genetic evidence indicate a direct regulatory link between Sox2 and Six3 during forebrain development.","method":"Genomic ChIP-based identification, in vivo transgenic reporter assay, biochemical and genetic validation","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP + transgenic enhancer assay + genetic evidence, single lab","pmids":["23792023"],"is_preprint":false},{"year":2016,"finding":"Six3 dosage-dependently determines HPE phenotype severity in mice: semilobar HPE results from severe downregulation of Shh expression in the rostral diencephalon ventral midline, while alobar HPE results from downregulation of Foxg1 expression in the anterior neural ectoderm; in vivo activation of Shh signaling rescues the semilobar but not alobar phenotype, establishing two distinct downstream pathways.","method":"Novel hypomorphic Six3 allele mouse model, Shh pathway activation rescue, molecular phenotyping","journal":"Development","confidence":"High","confidence_rationale":"Tier 2 — hypomorphic allele series + genetic rescue experiment distinguishing two pathways","pmids":["27770010"],"is_preprint":false},{"year":2017,"finding":"Six3 directly represses R-spondin 2 (Rspo2) expression during neuroretina differentiation; transient ectopic expression of Rspo2 in the anterior neural plate of transgenic mice is sufficient to inhibit neuroretina differentiation; Six3-null cells exert a non-cell-autonomous repressive effect on optic vesicle formation and neuroretina differentiation in chimeric eye organoids.","method":"Eye organoid system using ESC/iPSC-derived optic vesicles, Six3-/- iPSC generation, conditional null ESCs, transgenic mouse experiments, chimeric organoid assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1–2 — organoid reconstitution + transgenic in vivo validation + chimeric analysis, multiple orthogonal methods","pmids":["29117559"],"is_preprint":false},{"year":2017,"finding":"Six3 in a small population of anteroventral optic pit/vesicle progenitors at E8.5 is required for neuroretinal specification by repressing Wnt8b and maintaining Fgf8/MAPK signaling; lineage tracing showed Six3-Cre positive progenitors contribute to neuroretina and optic stalk but not RPE; Six3 deletion in these cells causes the progenitors to be lost and RPE to derive from Six3-Cre-negative cells.","method":"Cre-mediated lineage tracing in wild-type and Six3-deficient mice, conditional deletion, molecular signaling pathway analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — lineage tracing + conditional KO + signaling analysis, multiple orthogonal approaches","pmids":["28579317"],"is_preprint":false},{"year":2018,"finding":"SP8 and SP9 transcription factors drive expression of Six3 in a spatially restricted domain of the LGE subventricular zone; ChIP-Seq reveals SP9 directly binds the promoter and a putative enhancer of Six3; conditional deletion of Six3 prevents formation of most D2 MSNs, phenocopying Sp8/9 mutants, placing Six3 downstream of SP8/SP9 in a transcription pathway for D2 MSN production.","method":"Conditional deletion of Sp8, Sp9, and Six3 in mice, ChIP-Seq for SP9 binding to Six3 locus, neuronal subtype marker analysis","journal":"Development","confidence":"High","confidence_rationale":"Tier 1–2 — ChIP-Seq + conditional KO epistasis + phenotypic characterization","pmids":["29967281"],"is_preprint":false},{"year":2018,"finding":"SIX3 forms a complex with LSD1/NuRD(MTA3); affinity purification and mass spectrometry identified this complex; ChIP-on-chip identified WNT1 and FOXC2 as genomic targets of the SIX3/LSD1/NuRD(MTA3) complex, which inhibits carcinogenesis and metastasis in breast cancer cells.","method":"Affinity purification/mass spectrometry, ChIP-on-chip, functional tumor assays","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 — AP-MS complex identification + ChIP-on-chip target identification","pmids":["29463994"],"is_preprint":false},{"year":2018,"finding":"Six3 and Six6 are jointly required for maintenance of multipotent neuroretinal progenitors by suppressing Wnt/β-catenin signaling and promoting retinogenic factors; the double KO (DKO) reveals a functional redundancy: neither single KO shows the DKO phenotype, including ectopic upregulation of Wnt3a, Fzd1, CM markers, and loss of Sox2, Notch1, and Otx2.","method":"Six3 and Six6 double conditional knockout in mice, Wnt signaling stimulation experiments, molecular marker analysis","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — double KO genetic analysis + signaling pathway manipulation, orthogonal approaches","pmids":["30485816"],"is_preprint":false},{"year":2020,"finding":"EGFR activation induces DNA methylation of the SIX3 promoter through MAPK pathway; ERK binds ZNF263, abrogating its ubiquitination and stabilizing it; ZNF263 binds the SIX3 core promoter and recruits KAP1/HATS/DNMT corepressor complex, inducing transcriptional silencing of SIX3 through H3K27me3 and DNA methylation.","method":"Signaling pathway manipulation, Co-IP, ChIP, promoter methylation analysis, epistasis experiments","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — multiple biochemical methods establishing epigenetic silencing mechanism, single lab","pmids":["32051553"],"is_preprint":false},{"year":2020,"finding":"TRIM27 ubiquitinates and degrades SIX3 protein; TRIM27 acts as an E3 ubiquitin ligase for SIX3, leading to activation of Wnt/β-catenin signaling (which SIX3 normally represses) and promotion of NSCLC cell proliferation and metastasis.","method":"Co-IP, ubiquitination assays, knockdown/overexpression experiments in lung cancer cells and tissue analysis","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 2 — direct ubiquitination assay + functional rescue, single lab","pmids":["33264103"],"is_preprint":false},{"year":2021,"finding":"Six3 is required for the differentiation (but not proliferation) of D2-type medium spiny neuron precursor cells in the LGE; conditional overexpression of Six3 promotes LGE precursor differentiation; in the absence of Six3, abnormally differentiated D2 MSNs are eliminated by apoptosis postnatally.","method":"Conditional Six3 knockout and overexpression in mice, cell proliferation/apoptosis assays, neuronal marker analysis","journal":"Neuroscience bulletin","confidence":"Medium","confidence_rationale":"Tier 2 — conditional KO + overexpression with defined cellular phenotype, single lab","pmids":["34014554"],"is_preprint":false},{"year":2021,"finding":"SIX3 suppression in human adult pancreatic islets impairs insulin secretion; SIX3 loss leads to inappropriate expression of fetal β-cell genes, adult α-cell genes, and non-β-cell genes, indicating SIX3 maintains developmental fate of mature β cells; chromatin accessibility studies identified genes directly regulated by SIX3.","method":"shRNA-mediated knockdown in human islets, transcriptome analysis, chromatin accessibility (ATAC-seq), functional insulin secretion assay","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — human tissue KD + transcriptome + chromatin accessibility + functional assay, multiple orthogonal methods","pmids":["33446570"],"is_preprint":false},{"year":2001,"finding":"The orphan nuclear receptor NOR-1 interacts with Six3 in vitro and in yeast; the interaction requires the DNA binding and AF2 domains of NOR-1; Six3 has a negative effect on NOR-1 transactivation through the NBRE response element in a dose-dependent manner.","method":"Yeast two-hybrid screen, in vitro pull-down, cotransfection reporter assays","journal":"Developmental neuroscience","confidence":"Medium","confidence_rationale":"Tier 3 — Y2H + in vitro pull-down + reporter assay, single lab","pmids":["11173923"],"is_preprint":false},{"year":2003,"finding":"Six3 acts as a coactivator of nuclear receptor NOR-1 and as a corepressor of the fusion protein EWS/NOR-1; Six3 binds the DNA-binding domain of NOR-1 and the EWS domain of EWS/NOR-1 in GST pull-down assays; Six3 homeodomain is required for these interactions; in vivo interaction confirmed by mammalian two-hybrid in immortalized chondrocytes.","method":"RT-PCR in EMC tumors, GST pull-down assay, mammalian two-hybrid, cotransfection reporter assays","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — GST pull-down + mammalian two-hybrid + reporter assay with domain mapping","pmids":["12543801"],"is_preprint":false},{"year":2002,"finding":"Six3 bHLH co-factor screen identified ATH5, ATH3, NEUROD, and ASH1 as proteins that interact specifically with XSix3; the bHLH domain of NEUROD interacts with the SIX domain of XSix3, defining a new interaction interface.","method":"Yeast two-hybrid screen, biochemical domain-mapping analysis","journal":"Mechanisms of development","confidence":"Low","confidence_rationale":"Tier 3 — Y2H and domain mapping only, no in vivo functional follow-up in this paper","pmids":["12204251"],"is_preprint":false},{"year":2005,"finding":"An in vitro protein-protein interaction is detected between Six3 and Eya1; Six3 expression in the pre-placode lens ectoderm is initially Pax6-independent but subsequently both its expression and nuclear localization become Pax6-dependent.","method":"In vitro protein-protein interaction assay, immunohistochemistry in Pax6 mutant mice, nuclear localization analysis","journal":"Gene expression patterns","confidence":"Low","confidence_rationale":"Tier 3 — single in vitro interaction assay with limited functional follow-up","pmids":["16024294"],"is_preprint":false},{"year":2009,"finding":"EYA4 is co-immunoprecipitated with SIX3; EYA4 protein is recruited to the nucleus by SIX3; EYA4 cooperates with SIX3 in reporter gene assays as a transcriptional coactivator, demonstrating physical and functional association between EYA4 and SIX3.","method":"Co-immunoprecipitation, confocal microscopy for subcellular localization, reporter gene assays","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP + localization + reporter assay, single lab","pmids":["19606496"],"is_preprint":false},{"year":2010,"finding":"Six3 defines a novel DNA recognition sequence (TAATGTC) for its homeodomain; this is distinct from the common Six family recognition sequence (TGATAC); in vitro binding to TAATGTC and TGATAC sites shows similar affinities suggesting two distinct DNA-binding modes; ChIP in zebrafish embryos confirmed Six3a binding to promoter fragments containing the TAATGTC motif, which is involved in autoregulation.","method":"In vitro binding affinity analysis with single-nucleotide substitutions, transient reporter assays in zebrafish embryos, ChIP in zebrafish","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 1–2 — in vitro binding + ChIP + in vivo reporter, defines new recognition sequence","pmids":["20193042"],"is_preprint":false},{"year":2015,"finding":"SIX3 represses transcription of GnRH receptor (GnRHR) and the common α-subunit (Cga) genes in immature gonadotrope cell lines; SIX3 and SIX6 can functionally compensate for each other in gonadotrope gene regulation; SIX6 repression requires interaction with TLE corepressor proteins and competition for DNA-binding sites with Pitx1.","method":"siRNA knockdown in gonadotrope cell lines, Six6 knockout mouse analysis, reporter and binding assays","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 — KD in cell lines + KO mouse + reporter assays, single lab","pmids":["25915183"],"is_preprint":false},{"year":2017,"finding":"SIX3 directly represses transcription of aurora kinase A (AURKA) and aurora kinase B (AURKB) in astrocytoma cells in a dose-dependent manner; ChIP confirmed SIX3 binding to AURKA and AURKB promoter regions; SIX3 increases p53 activity at the post-translational level through negative regulation of AURKA/AURKB; AURKA and AURKB interact to stabilize each other, an interaction not affected by SIX3 overexpression.","method":"ChIP, luciferase reporter assay, Co-IP for AURKA-AURKB interaction, flow cytometry, intracranial xenograft","journal":"Journal of hematology & oncology","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP + reporter assay + Co-IP + in vivo tumor model","pmids":["28595628"],"is_preprint":false}],"current_model":"SIX3 is a homeodomain transcription factor that functions primarily as a Groucho/TLE-dependent transcriptional repressor (via an eh1-like motif in its Six domain) of Wnt1, Wnt8b, Shh-regulatory enhancers, and other target genes in the anterior neural plate and developing eye, while also acting as a direct transcriptional activator of Pax6, Sox2, Shh (via SBE2), and rhodopsin; it promotes cell proliferation non-transcriptionally by competing with Cdt1 to bind geminin, and its activity is modulated by interactions with multiple co-factors including Groucho/TLE family members, EYA family members, geminin, MTA1 (which epigenetically silences Six3 via HDAC-dependent chromatin remodeling), and the lncRNA Six3OS (which scaffolds Ezh2 and Eya to Six3 target genes), with haploinsufficiency causing holoprosencephaly through failure to activate Shh in the rostral diencephalon ventral midline."},"narrative":{"teleology":[{"year":1995,"claim":"Identification of Six3 as a vertebrate homologue of Drosophila sine oculis established that a homeodomain transcription factor with anterior-restricted expression exists independently of the Pax6 pathway, opening the question of its specific function in head development.","evidence":"Gene cloning, sequence analysis, in situ hybridization in wild-type and Pax6 mutant mouse embryos","pmids":["8575305"],"confidence":"High","gaps":["No target genes identified","No loss-of-function phenotype characterized","Relationship to other anterior transcription factors undefined"]},{"year":1996,"claim":"Demonstrating that ectopic Six3 expression induces lens formation and retinal primordia in fish established Six3 as a sufficient master regulator of eye field identity, not merely a marker.","evidence":"Ectopic RNA injection in medaka with histological and marker analysis","pmids":["9025075","10090721"],"confidence":"High","gaps":["No loss-of-function data","Target gene cascades downstream of Six3 unknown","Mechanism of action (activator vs. repressor) unresolved"]},{"year":1999,"claim":"Discovery that homeodomain mutations in human SIX3 cause holoprosencephaly (HPE2) established that SIX3 is essential for forebrain midline development and linked its transcriptional activity to a major human congenital malformation.","evidence":"Positional cloning and mutational analysis in HPE patient families","pmids":["10369266"],"confidence":"High","gaps":["Direct transcriptional targets in forebrain unknown","Mechanism by which mutations cause HPE unresolved","Animal model of haploinsufficiency not yet available"]},{"year":2001,"claim":"Identifying Six3 as a Groucho/TLE-dependent transcriptional repressor that uses an eh1-like motif resolved the long-standing question of whether Six3 acts as an activator or repressor, revealing that its primary developmental function in forebrain expansion requires corepressor recruitment.","evidence":"Yeast two-hybrid, Co-IP, site-directed mutagenesis of eh1 motif, zebrafish overexpression phenotyping","pmids":["11401394","12050133","12441302"],"confidence":"High","gaps":["Direct genomic targets of repression not identified by ChIP","Whether Six3 also has activator functions remained unclear","Role of individual Groucho/TLE family members not distinguished in vivo"]},{"year":2003,"claim":"Six3-null mouse analysis revealed that Six3 directly binds and represses Wnt1 transcription in the anterior neuroectoderm, and genetic epistasis showed Six3 acts upstream of Wnt signaling, establishing the first direct target gene and the core mechanism by which Six3 protects forebrain identity.","evidence":"Six3 knockout mouse, in vivo/in vitro DNA-binding assays, ectopic expression in chick/zebrafish, headless/tcf3 rescue","pmids":["12569128"],"confidence":"High","gaps":["Whether Wnt1 is the sole critical target or one of several Wnt genes repressed was unknown","The Six3-Shh regulatory relationship not yet characterized","Mechanism of anterior-restricted Six3 expression unresolved"]},{"year":2004,"claim":"Discovery that Six3 binds geminin and competes with Cdt1 for geminin binding revealed a non-transcriptional mechanism for promoting cell proliferation, explaining how Six3 can drive progenitor expansion independently of its DNA-binding activity.","evidence":"Yeast two-hybrid, direct protein competition assay, genetic rescue in medaka","pmids":["14973488"],"confidence":"High","gaps":["Relative contribution of transcriptional vs. geminin-mediated proliferation not quantified","Whether geminin interaction occurs in mammalian forebrain progenitors not confirmed in vivo","Structural basis of competitive binding unknown"]},{"year":2006,"claim":"Conditional deletion of Six3 in lens ectoderm combined with ChIP and EMSA demonstrated that Six3 directly activates Pax6 and Sox2, establishing that Six3 functions as a transcriptional activator for key lens-induction genes, not solely as a repressor.","evidence":"Conditional KO in mouse, ChIP, EMSA, luciferase reporter, chick misexpression","pmids":["17066077"],"confidence":"High","gaps":["Cofactors converting Six3 from repressor to activator mode not identified","Whether Six3 activator function is relevant in forebrain (not just lens) undetermined"]},{"year":2007,"claim":"Identifying MTA1 as a cofactor that epigenetically silences Six3 itself via HDAC-dependent chromatin remodeling, and demonstrating that Six3 homeodomain directly activates rhodopsin transcription (with HPE mutations ablating this binding), established a regulatory feedback on Six3 levels and extended its activator role to post-mitotic photoreceptors.","evidence":"ChIP, Co-IP, MTA1-null mouse analysis, luciferase reporter with HPE mutant proteins","pmids":["17666527"],"confidence":"High","gaps":["Whether MTA1-mediated silencing of Six3 is relevant in forebrain HPE pathogenesis unknown","Full repertoire of Six3 activator targets in retina not catalogued"]},{"year":2008,"claim":"Demonstrating that Six3 directly binds and activates the remote Shh brain enhancer SBE2, and that Six3 haploinsufficiency recapitulates human HPE through failure to activate Shh in the rostral diencephalon ventral midline, closed the mechanistic gap between SIX3 mutations and HPE pathogenesis via a direct Six3→Shh regulatory axis.","evidence":"DNA affinity-capture assay, transgenic enhancer assay, ChIP at Shh locus, Six3 haploinsufficient mouse models, functional analysis of 46 HPE mutations in zebrafish","pmids":["18836447","18694563","18791198"],"confidence":"High","gaps":["How the same transcription factor switches between repression (Wnt1) and activation (Shh) mechanistically unresolved","Modifier genes explaining variable HPE expressivity not identified","Whether all HPE mutations act through SBE2 or through additional enhancers unknown"]},{"year":2010,"claim":"ChIP-validated direct repression of Wnt8b by Six3 in the neuroretina, with transgenic Wnt8b phenocopying Six3 loss, established a second Wnt target through which Six3 specifies neuroretinal fate distinct from its Wnt1-mediated forebrain function.","evidence":"Conditional Six3 KO in mouse, ChIP, transgenic Wnt8b overexpression","pmids":["20890044"],"confidence":"High","gaps":["Whether Wnt8b repression and Wnt1 repression employ the same corepressor complexes untested","Genome-wide catalog of Six3-bound Wnt pathway genes absent"]},{"year":2011,"claim":"Discovery that the lncRNA Six3OS scaffolds Ezh2 and Eya to Six3 target genes revealed an epigenetic layer of Six3 regulation operating at the chromatin level, modulating target gene specificity during retinal differentiation without affecting Six3 expression itself.","evidence":"Overexpression/knockdown, direct binding assays for Six3OS-Ezh2 and Six3OS-Eya interactions, retinal specification assays","pmids":["21936910"],"confidence":"High","gaps":["Specific genomic loci where Six3OS acts not mapped","Whether Six3OS is required in vivo for eye development not tested by genetic deletion","Stoichiometry of the Six3/Six3OS/Ezh2/Eya complex uncharacterized"]},{"year":2016,"claim":"A hypomorphic allele series showed that Six3 dosage determines HPE severity through two distinct downstream pathways—Shh for semilobar and Foxg1 for alobar HPE—explaining the clinical spectrum of SIX3-associated HPE.","evidence":"Novel hypomorphic Six3 allele mouse model, Shh pathway activation rescue, molecular phenotyping","pmids":["27770010"],"confidence":"High","gaps":["Whether Six3 directly regulates Foxg1 or acts indirectly not resolved","Therapeutic implications of Shh rescue for semilobar HPE not explored"]},{"year":2017,"claim":"Identification of Rspo2 as a direct Six3 target repressed during neuroretina differentiation, with chimeric organoid experiments revealing non-cell-autonomous effects of Six3-null cells, extended the model to include Wnt-potentiating ligands and demonstrated organoid-based reconstitution of Six3 function.","evidence":"ESC/iPSC-derived eye organoids, Six3-null iPSCs, chimeric organoid assay, transgenic mice","pmids":["29117559"],"confidence":"High","gaps":["Identity of the non-cell-autonomous signal from Six3-null cells unknown","Whether Rspo2 derepression alone accounts for the organoid phenotype untested"]},{"year":2018,"claim":"Affinity purification identified a SIX3/LSD1/NuRD(MTA3) complex and ChIP-on-chip mapped its genomic targets including WNT1, providing a biochemical framework for how Six3 recruits histone demethylase/deacetylase machinery to achieve transcriptional repression at specific loci.","evidence":"AP-MS, ChIP-on-chip, functional tumor assays in breast cancer cells","pmids":["29463994"],"confidence":"Medium","gaps":["Whether the LSD1/NuRD(MTA3) complex operates in developing forebrain or only in cancer cells not established","Genome-wide overlap with Groucho/TLE-dependent repression untested","Structural basis of the SIX3-LSD1-NuRD interaction unknown"]},{"year":2021,"claim":"Demonstrating that SIX3 knockdown in human adult pancreatic islets impairs insulin secretion and derepresses fetal/non-β-cell gene programs extended Six3 function beyond development to maintenance of mature cell identity in an endocrine context.","evidence":"shRNA knockdown in human islets, RNA-seq, ATAC-seq, insulin secretion assay","pmids":["33446570"],"confidence":"High","gaps":["Direct SIX3 target genes in β-cells not fully distinguished from indirect effects","Whether SIX3 loss contributes to type 2 diabetes pathogenesis in humans unknown","Cofactor complex used by SIX3 in β-cells not characterized"]},{"year":null,"claim":"Key open questions include: (1) the structural and cofactor basis determining whether Six3 acts as a repressor or activator at specific loci; (2) a genome-wide map of direct Six3 binding sites across developmental stages; (3) the in vivo significance of the geminin interaction in mammalian forebrain progenitors; and (4) whether SIX3-based regulatory circuits are therapeutically targetable in HPE or diabetes.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal structure of Six3 in complex with DNA or cofactors","Genome-wide ChIP-seq across developmental time points lacking for most tissues","In vivo functional significance of many reported protein interactions (NOR-1, bHLH factors) unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,5,6,8,13,17,41]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[4,5,6,8,13,14,17,20,43]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,13,14,40]}],"pathway":[{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[1,3,8,11,13,15,18,20,26,27,28,29]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,15,16,20,24,31]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[4,5,6,13,14,17,43]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[2,18,19,26]}],"complexes":["SIX3/Groucho(TLE) corepressor complex","SIX3/LSD1/NuRD(MTA3) complex","SIX3/geminin complex"],"partners":["TLE1","GRG5","GMNN","MTA1","EYA1","EYA4","PAX6","LSD1"],"other_free_text":[]},"mechanistic_narrative":"SIX3 is a homeodomain transcription factor that orchestrates anterior neural plate patterning, eye development, and forebrain specification by functioning as both a transcriptional repressor and activator depending on cofactor context. As a repressor, SIX3 recruits Groucho/TLE corepressors via an eh1-like motif in its Six domain to directly silence Wnt1, Wnt8b, Rspo2, and Bmp4, thereby protecting anterior neuroectoderm from posteriorizing signals and enabling neuroretinal and telencephalic specification [PMID:12050133, PMID:12569128, PMID:20890044, PMID:29117559]; as an activator, it directly binds and stimulates transcription of Pax6, Sox2, Shh (via the remote SBE2 enhancer), and rhodopsin, often cooperating with cofactors such as Crx, NRL, and EYA family members [PMID:17066077, PMID:18836447, PMID:17666527]. SIX3 also promotes cell proliferation non-transcriptionally by competing with Cdt1 for geminin binding, thereby relieving replication licensing inhibition [PMID:14973488]. Haploinsufficiency of SIX3 causes holoprosencephaly (HPE2) in humans and mice through failure to activate Shh in the rostral diencephalon ventral midline, with disease severity correlating with dosage-dependent effects on Shh and Foxg1 expression [PMID:10369266, PMID:18694563, PMID:27770010]."},"prefetch_data":{"uniprot":{"accession":"O95343","full_name":"Homeobox protein SIX3","aliases":["Sine oculis homeobox homolog 3"],"length_aa":332,"mass_kda":35.5,"function":"Transcriptional regulator which can act as both a transcriptional repressor and activator by binding a ATTA homeodomain core recognition sequence on these target genes. During forebrain development represses WNT1 expression allowing zona limitans intrathalamica formation and thereby ensuring proper anterio-posterior patterning of the diencephalon and formation of the rostral diencephalon. Acts as a direct upstream activator of SHH expression in the rostral diencephalon ventral midline and that in turn SHH maintains its expression. In addition, Six3 activity is required for the formation of the telencephalon. During postnatal stages of brain development is necessary for ependymal cell maturation by promoting the maturation of radial glia into ependymal cells through regulation of neuroblast proliferation and migration. Acts on the proliferation and differentiation of neural progenitor cells through activating transcription of CCND1 and CCND2. During early lens formation plays a role in lens induction and specification by activating directly PAX6 in the presumptive lens ectoderm. In turn PAX6 activates SIX3 resulting in activation of PDGFRA and CCND1 promoting cell proliferation. Also is required for the neuroretina development by directly suppressing WNT8B expression in the anterior neural plate territory. Its action during retina development and lens morphogenesis is TLE5 and TLE4-dependent manner. Furthermore, during eye development regulates several genes expression. Before and during early lens development represses the CRYGF promoter by binding a SIX repressor element. Directly activates RHO transcription, or cooperates with CRX or NRL. Six3 also functions in the formation of the proximodistal axis of the optic cup, and promotes the formation of optic vesicles-like structures. During pituitary development, acts in parallel or alternatively with HESX1 to control cell proliferation through Wnt/beta-catenin pathway (By similarity). Plays a role in eye development by suppressing WNT1 expression and in dorsal-ventral patterning by repressing BMP signaling pathway","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O95343/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SIX3","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SIX3","total_profiled":1310},"omim":[{"mim_id":"621143","title":"HOLOPROSENCEPHALY 10; HPE10","url":"https://www.omim.org/entry/621143"},{"mim_id":"621003","title":"TRANSCRIPTION FACTOR Sp9; SP9","url":"https://www.omim.org/entry/621003"},{"mim_id":"615465","title":"HARTSFIELD SYNDROME; HRTFDS","url":"https://www.omim.org/entry/615465"},{"mim_id":"610829","title":"HOLOPROSENCEPHALY 9; HPE9","url":"https://www.omim.org/entry/610829"},{"mim_id":"609637","title":"HOLOPROSENCEPHALY 5; HPE5","url":"https://www.omim.org/entry/609637"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":36.9},{"tissue":"pituitary gland","ntpm":25.1},{"tissue":"retina","ntpm":23.5}],"url":"https://www.proteinatlas.org/search/SIX3"},"hgnc":{"alias_symbol":[],"prev_symbol":["HPE2"]},"alphafold":{"accession":"O95343","domains":[{"cath_id":"1.25.40","chopping":"88-195","consensus_level":"high","plddt":88.8081,"start":88,"end":195},{"cath_id":"1.10.10.60","chopping":"214-274","consensus_level":"high","plddt":92.0108,"start":214,"end":274}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95343","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95343-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95343-F1-predicted_aligned_error_v6.png","plddt_mean":67.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SIX3","jax_strain_url":"https://www.jax.org/strain/search?query=SIX3"},"sequence":{"accession":"O95343","fasta_url":"https://rest.uniprot.org/uniprotkb/O95343.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95343/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95343"}},"corpus_meta":[{"pmid":"8575305","id":"PMC_8575305","title":"Six3, a murine homologue of the sine oculis gene, demarcates the most anterior border of the developing neural plate and is expressed during eye development.","date":"1995","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/8575305","citation_count":589,"is_preprint":false},{"pmid":"12569128","id":"PMC_12569128","title":"Six3 repression of Wnt signaling in the anterior neuroectoderm is essential for vertebrate forebrain development.","date":"2003","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/12569128","citation_count":390,"is_preprint":false},{"pmid":"10369266","id":"PMC_10369266","title":"Mutations in the homeodomain of the human SIX3 gene cause holoprosencephaly.","date":"1999","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10369266","citation_count":294,"is_preprint":false},{"pmid":"14973488","id":"PMC_14973488","title":"Direct interaction of geminin and Six3 in eye development.","date":"2004","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/14973488","citation_count":200,"is_preprint":false},{"pmid":"10090721","id":"PMC_10090721","title":"Six3 overexpression initiates the formation of ectopic retina.","date":"1999","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/10090721","citation_count":186,"is_preprint":false},{"pmid":"12050133","id":"PMC_12050133","title":"Six3-mediated auto repression and eye development requires its interaction with members of the Groucho-related family of co-repressors.","date":"2002","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/12050133","citation_count":177,"is_preprint":false},{"pmid":"9655819","id":"PMC_9655819","title":"Overexpression of the forebrain-specific homeobox gene six3 induces rostral forebrain enlargement in zebrafish.","date":"1998","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/9655819","citation_count":163,"is_preprint":false},{"pmid":"10473118","id":"PMC_10473118","title":"Six6 (Optx2) is a novel murine Six3-related homeobox gene that demarcates the presumptive pituitary/hypothalamic axis and the ventral optic stalk.","date":"1999","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/10473118","citation_count":150,"is_preprint":false},{"pmid":"11401394","id":"PMC_11401394","title":"The homeobox protein Six3 interacts with the Groucho corepressor and acts as a transcriptional repressor in eye and forebrain formation.","date":"2001","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/11401394","citation_count":148,"is_preprint":false},{"pmid":"18836447","id":"PMC_18836447","title":"Regulation of a remote Shh forebrain enhancer by the Six3 homeoprotein.","date":"2008","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18836447","citation_count":145,"is_preprint":false},{"pmid":"9025075","id":"PMC_9025075","title":"Ectopic lens induction in fish in response to the murine homeobox gene Six3.","date":"1996","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/9025075","citation_count":143,"is_preprint":false},{"pmid":"17066077","id":"PMC_17066077","title":"Six3 activation of Pax6 expression is essential for mammalian lens induction and specification.","date":"2006","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/17066077","citation_count":138,"is_preprint":false},{"pmid":"18694563","id":"PMC_18694563","title":"Haploinsufficiency of Six3 fails to activate Sonic hedgehog expression in the ventral forebrain and causes holoprosencephaly.","date":"2008","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/18694563","citation_count":135,"is_preprint":false},{"pmid":"21936910","id":"PMC_21936910","title":"The long noncoding RNA Six3OS acts in trans to regulate retinal development by modulating Six3 activity.","date":"2011","source":"Neural development","url":"https://pubmed.ncbi.nlm.nih.gov/21936910","citation_count":128,"is_preprint":false},{"pmid":"9651515","id":"PMC_9651515","title":"Six3, a medaka homologue of the Drosophila homeobox gene sine oculis is expressed in the anterior embryonic shield and the developing eye.","date":"1998","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/9651515","citation_count":127,"is_preprint":false},{"pmid":"9545529","id":"PMC_9545529","title":"Expression of two zebrafish homologues of the murine Six3 gene demarcates the initial eye primordia.","date":"1998","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/9545529","citation_count":126,"is_preprint":false},{"pmid":"15221788","id":"PMC_15221788","title":"Molecular screening of SHH, ZIC2, SIX3, and TGIF genes in patients with features of holoprosencephaly spectrum: Mutation review and genotype-phenotype correlations.","date":"2004","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/15221788","citation_count":120,"is_preprint":false},{"pmid":"21190549","id":"PMC_21190549","title":"Six3 demarcates the anterior-most developing brain region in bilaterian animals.","date":"2010","source":"EvoDevo","url":"https://pubmed.ncbi.nlm.nih.gov/21190549","citation_count":118,"is_preprint":false},{"pmid":"23483856","id":"PMC_23483856","title":"The bilaterian head patterning gene six3/6 controls aboral domain development in a cnidarian.","date":"2013","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/23483856","citation_count":117,"is_preprint":false},{"pmid":"12441302","id":"PMC_12441302","title":"Six3 and Six6 activity is modulated by members of the groucho family.","date":"2003","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/12441302","citation_count":114,"is_preprint":false},{"pmid":"19270175","id":"PMC_19270175","title":"The sea urchin animal pole domain is a Six3-dependent neurogenic patterning center.","date":"2009","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/19270175","citation_count":95,"is_preprint":false},{"pmid":"16341014","id":"PMC_16341014","title":"BMP inhibition-driven regulation of six-3 underlies induction of newt lens regeneration.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/16341014","citation_count":91,"is_preprint":false},{"pmid":"20890044","id":"PMC_20890044","title":"Neuroretina specification in mouse embryos requires Six3-mediated suppression of Wnt8b in the anterior neural plate.","date":"2010","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/20890044","citation_count":90,"is_preprint":false},{"pmid":"16226737","id":"PMC_16226737","title":"Lhx2 mediates the activity of Six3 in zebrafish forebrain growth.","date":"2005","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/16226737","citation_count":88,"is_preprint":false},{"pmid":"15843413","id":"PMC_15843413","title":"Six3 functions in anterior neural plate specification by promoting cell proliferation and inhibiting Bmp4 expression.","date":"2005","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/15843413","citation_count":74,"is_preprint":false},{"pmid":"12072567","id":"PMC_12072567","title":"Mutually regulated expression of Pax6 and Six3 and its implications for the Pax6 haploinsufficient lens phenotype.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12072567","citation_count":72,"is_preprint":false},{"pmid":"19346217","id":"PMC_19346217","title":"Clinical spectrum of SIX3-associated mutations in holoprosencephaly: correlation between genotype, phenotype and function.","date":"2009","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19346217","citation_count":70,"is_preprint":false},{"pmid":"10704858","id":"PMC_10704858","title":"Cloning and expression of xSix3, the Xenopus homologue of murine Six3.","date":"2000","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/10704858","citation_count":69,"is_preprint":false},{"pmid":"12851489","id":"PMC_12851489","title":"Regulation of proliferation, cell fate specification and differentiation by the homeodomain proteins Prox1, Six3, and Chx10 in the developing retina.","date":"2003","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/12851489","citation_count":69,"is_preprint":false},{"pmid":"22216011","id":"PMC_22216011","title":"Candidate gene screen in the red flour beetle Tribolium reveals six3 as ancient regulator of anterior median head and central complex development.","date":"2011","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22216011","citation_count":66,"is_preprint":false},{"pmid":"18094027","id":"PMC_18094027","title":"Six3 inactivation causes progressive caudalization and aberrant patterning of the mammalian diencephalon.","date":"2007","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/18094027","citation_count":65,"is_preprint":false},{"pmid":"11458394","id":"PMC_11458394","title":"Six3 promotes the formation of ectopic optic vesicle-like structures in mouse embryos.","date":"2001","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/11458394","citation_count":64,"is_preprint":false},{"pmid":"26989171","id":"PMC_26989171","title":"Development of the aboral domain in Nematostella requires β-catenin and the opposing activities of Six3/6 and Frizzled5/8.","date":"2016","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/26989171","citation_count":59,"is_preprint":false},{"pmid":"29967281","id":"PMC_29967281","title":"SP8 and SP9 coordinately promote D2-type medium spiny neuron production by activating Six3 expression.","date":"2018","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/29967281","citation_count":55,"is_preprint":false},{"pmid":"17666527","id":"PMC_17666527","title":"Repression of Six3 by a corepressor regulates rhodopsin expression.","date":"2007","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/17666527","citation_count":55,"is_preprint":false},{"pmid":"11039582","id":"PMC_11039582","title":"A new mutation in the six-domain of SIX3 gene causes holoprosencephaly.","date":"2000","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/11039582","citation_count":54,"is_preprint":false},{"pmid":"18775421","id":"PMC_18775421","title":"Genetic interaction between the homeobox transcription factors HESX1 and SIX3 is required for normal pituitary development.","date":"2008","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/18775421","citation_count":51,"is_preprint":false},{"pmid":"16024294","id":"PMC_16024294","title":"Pax6-dependence of Six3, Eya1 and Dach1 expression during lens and nasal placode induction.","date":"2005","source":"Gene expression patterns : GEP","url":"https://pubmed.ncbi.nlm.nih.gov/16024294","citation_count":51,"is_preprint":false},{"pmid":"30485816","id":"PMC_30485816","title":"Six3 and Six6 Are Jointly Required for the Maintenance of Multipotent Retinal Progenitors through Both Positive and Negative Regulation.","date":"2018","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/30485816","citation_count":50,"is_preprint":false},{"pmid":"17678854","id":"PMC_17678854","title":"Six3 represses nodal activity to establish early brain asymmetry in zebrafish.","date":"2007","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/17678854","citation_count":50,"is_preprint":false},{"pmid":"8824878","id":"PMC_8824878","title":"Molecular characterization of breakpoints in patients with holoprosencephaly and definition of the HPE2 critical region 2p21.","date":"1996","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8824878","citation_count":49,"is_preprint":false},{"pmid":"22310223","id":"PMC_22310223","title":"Utilizing prospective sequence analysis of SHH, ZIC2, SIX3 and TGIF in holoprosencephaly probands to describe the parameters limiting the observed frequency of mutant gene×gene interactions.","date":"2012","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/22310223","citation_count":47,"is_preprint":false},{"pmid":"11139622","id":"PMC_11139622","title":"Antagonistic action of Six3 and Prox1 at the gamma-crystallin promoter.","date":"2001","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/11139622","citation_count":44,"is_preprint":false},{"pmid":"18791198","id":"PMC_18791198","title":"Mutations in the human SIX3 gene in holoprosencephaly are loss of function.","date":"2008","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18791198","citation_count":44,"is_preprint":false},{"pmid":"22071110","id":"PMC_22071110","title":"Six3 is required for ependymal cell maturation.","date":"2011","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/22071110","citation_count":39,"is_preprint":false},{"pmid":"17576749","id":"PMC_17576749","title":"Six3 controls the neural progenitor status in the murine CNS.","date":"2007","source":"Cerebral cortex (New York, N.Y. : 1991)","url":"https://pubmed.ncbi.nlm.nih.gov/17576749","citation_count":37,"is_preprint":false},{"pmid":"19353631","id":"PMC_19353631","title":"A novel SIX3 mutation segregates with holoprosencephaly in a large family.","date":"2009","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/19353631","citation_count":36,"is_preprint":false},{"pmid":"26244086","id":"PMC_26244086","title":"Expression of Hox, Cdx, and Six3/6 genes in the hoplonemertean Pantinonemertes californiensis offers insight into the evolution of maximally indirect development in the phylum Nemertea.","date":"2015","source":"EvoDevo","url":"https://pubmed.ncbi.nlm.nih.gov/26244086","citation_count":36,"is_preprint":false},{"pmid":"20157829","id":"PMC_20157829","title":"Heterozygous mutations in SIX3 and SHH are associated with schizencephaly and further expand the clinical spectrum of holoprosencephaly.","date":"2010","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20157829","citation_count":36,"is_preprint":false},{"pmid":"20682799","id":"PMC_20682799","title":"Metastasis-associated protein 1 and its short form variant stimulates Wnt1 transcription through promoting its derepression from Six3 corepressor.","date":"2010","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/20682799","citation_count":36,"is_preprint":false},{"pmid":"23625086","id":"PMC_23625086","title":"The expression pattern of the genes engrailed, pax6, otd and six3 with special respect to head and eye development in Euperipatoides kanangrensis Reid 1996 (Onychophora: Peripatopsidae).","date":"2013","source":"Development genes and evolution","url":"https://pubmed.ncbi.nlm.nih.gov/23625086","citation_count":36,"is_preprint":false},{"pmid":"12543801","id":"PMC_12543801","title":"The homeotic protein Six3 is a coactivator of the nuclear receptor NOR-1 and a corepressor of the fusion protein EWS/NOR-1 in human extraskeletal myxoid chondrosarcomas.","date":"2003","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/12543801","citation_count":35,"is_preprint":false},{"pmid":"33446570","id":"PMC_33446570","title":"SIX2 and SIX3 coordinately regulate functional maturity and fate of human pancreatic β cells.","date":"2021","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/33446570","citation_count":34,"is_preprint":false},{"pmid":"25915183","id":"PMC_25915183","title":"Homeodomain Proteins SIX3 and SIX6 Regulate Gonadotrope-specific Genes During Pituitary Development.","date":"2015","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/25915183","citation_count":34,"is_preprint":false},{"pmid":"9714724","id":"PMC_9714724","title":"Transient expression of a novel Six3-related zebrafish gene during gastrulation and eye formation.","date":"1998","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/9714724","citation_count":34,"is_preprint":false},{"pmid":"29463994","id":"PMC_29463994","title":"The Homeotic Protein SIX3 Suppresses Carcinogenesis and Metastasis through Recruiting the LSD1/NuRD(MTA3) Complex.","date":"2018","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/29463994","citation_count":33,"is_preprint":false},{"pmid":"32051553","id":"PMC_32051553","title":"The EGFR-ZNF263 signaling axis silences SIX3 in glioblastoma epigenetically.","date":"2020","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/32051553","citation_count":33,"is_preprint":false},{"pmid":"12204251","id":"PMC_12204251","title":"A screen for co-factors of Six3.","date":"2002","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/12204251","citation_count":33,"is_preprint":false},{"pmid":"22736245","id":"PMC_22736245","title":"Six3 cooperates with Hedgehog signaling to specify ventral telencephalon by promoting early expression of Foxg1a and repressing Wnt signaling.","date":"2012","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/22736245","citation_count":33,"is_preprint":false},{"pmid":"28595628","id":"PMC_28595628","title":"SIX3, a tumor suppressor, inhibits astrocytoma tumorigenesis by transcriptional repression of AURKA/B.","date":"2017","source":"Journal of hematology & oncology","url":"https://pubmed.ncbi.nlm.nih.gov/28595628","citation_count":33,"is_preprint":false},{"pmid":"20531442","id":"PMC_20531442","title":"The unfolding clinical spectrum of holoprosencephaly due to mutations in SHH, ZIC2, SIX3 and TGIF genes.","date":"2010","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/20531442","citation_count":32,"is_preprint":false},{"pmid":"9889003","id":"PMC_9889003","title":"Genomic cloning, structure, expression pattern, and chromosomal location of the human SIX3 gene.","date":"1999","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9889003","citation_count":32,"is_preprint":false},{"pmid":"33264103","id":"PMC_33264103","title":"TRIM27 acts as an oncogene and regulates cell proliferation and metastasis in non-small cell lung cancer through SIX3-β-catenin signaling.","date":"2020","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/33264103","citation_count":30,"is_preprint":false},{"pmid":"23977152","id":"PMC_23977152","title":"Down-regulation of SIX3 is associated with clinical outcome in lung adenocarcinoma.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23977152","citation_count":29,"is_preprint":false},{"pmid":"29170429","id":"PMC_29170429","title":"Genome-wide meta-analysis in Japanese populations identifies novel variants at the TMC6-TMC8 and SIX3-SIX2 loci associated with HbA1c.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29170429","citation_count":28,"is_preprint":false},{"pmid":"17001667","id":"PMC_17001667","title":"SIX3 mutations with holoprosencephaly.","date":"2006","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/17001667","citation_count":28,"is_preprint":false},{"pmid":"29117559","id":"PMC_29117559","title":"An Eye Organoid Approach Identifies Six3 Suppression of R-spondin 2 as a Critical Step in Mouse Neuroretina Differentiation.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/29117559","citation_count":25,"is_preprint":false},{"pmid":"16118513","id":"PMC_16118513","title":"Agonistic and antagonistic action of AP2, Msx2, Pax6, Prox1 AND Six3 in the regulation of Sox2 expression.","date":"2005","source":"Ophthalmic research","url":"https://pubmed.ncbi.nlm.nih.gov/16118513","citation_count":24,"is_preprint":false},{"pmid":"27770010","id":"PMC_27770010","title":"Six3 dosage mediates the pathogenesis of holoprosencephaly.","date":"2016","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/27770010","citation_count":24,"is_preprint":false},{"pmid":"12167403","id":"PMC_12167403","title":"The homeobox gene Six3 is a potential regulator of anterior segment formation in the chick eye.","date":"2002","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/12167403","citation_count":22,"is_preprint":false},{"pmid":"26822689","id":"PMC_26822689","title":"Six3 regulates optic nerve development via multiple mechanisms.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26822689","citation_count":22,"is_preprint":false},{"pmid":"34014554","id":"PMC_34014554","title":"Homeobox Gene Six3 is Required for the Differentiation of D2-Type Medium Spiny Neurons.","date":"2021","source":"Neuroscience bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/34014554","citation_count":21,"is_preprint":false},{"pmid":"19606496","id":"PMC_19606496","title":"EYA4, deleted in a case with middle interhemispheric variant of holoprosencephaly, interacts with SIX3 both physically and functionally.","date":"2009","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/19606496","citation_count":21,"is_preprint":false},{"pmid":"23478590","id":"PMC_23478590","title":"Loss of the six3/6 controlling pathways might have resulted in pinhole-eye evolution in Nautilus.","date":"2013","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/23478590","citation_count":20,"is_preprint":false},{"pmid":"34545072","id":"PMC_34545072","title":"Long noncoding RNA DLGAP1-AS2 facilitates Wnt1 transcription through physically interacting with Six3 and drives the malignancy of gastric cancer.","date":"2021","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/34545072","citation_count":19,"is_preprint":false},{"pmid":"15262426","id":"PMC_15262426","title":"Coexpression of NOR1 and SIX3 proteins in extraskeletal myxoid chondrosarcomas without detectable NR4A3 fusion genes.","date":"2004","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/15262426","citation_count":19,"is_preprint":false},{"pmid":"15953543","id":"PMC_15953543","title":"Expression analysis of SIX3 and SIX6 in human tissues reveals differences in expression and a novel correlation between the expression of SIX3 and the genes encoding isocitrate dehyhrogenase and cadherin 18.","date":"2005","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/15953543","citation_count":19,"is_preprint":false},{"pmid":"32040712","id":"PMC_32040712","title":"six3 acts upstream of foxQ2 in labrum and neural development in the spider Parasteatoda tepidariorum.","date":"2020","source":"Development genes and evolution","url":"https://pubmed.ncbi.nlm.nih.gov/32040712","citation_count":18,"is_preprint":false},{"pmid":"28579317","id":"PMC_28579317","title":"Six3 in a small population of progenitors at E8.5 is required for neuroretinal specification via regulating cell signaling and survival in mice.","date":"2017","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/28579317","citation_count":18,"is_preprint":false},{"pmid":"25517354","id":"PMC_25517354","title":"Pax6- and Six3-mediated induction of lens cell fate in mouse and human ES cells.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25517354","citation_count":18,"is_preprint":false},{"pmid":"30261489","id":"PMC_30261489","title":"Haploinsufficiency of Homeodomain Proteins Six3, Vax1, and Otx2 Causes Subfertility in Mice via Distinct Mechanisms.","date":"2018","source":"Neuroendocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/30261489","citation_count":17,"is_preprint":false},{"pmid":"34212416","id":"PMC_34212416","title":"The transcription factors SIX3 and VAX1 are required for suprachiasmatic nucleus circadian output and fertility in female mice.","date":"2021","source":"Journal of neuroscience research","url":"https://pubmed.ncbi.nlm.nih.gov/34212416","citation_count":17,"is_preprint":false},{"pmid":"12951074","id":"PMC_12951074","title":"Retinal expression of zebrafish six3.1 and its regulation by Pax6.","date":"2003","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/12951074","citation_count":16,"is_preprint":false},{"pmid":"10415461","id":"PMC_10415461","title":"Sequence and location of SIX3, a homeobox gene expressed in the human eye.","date":"1999","source":"Ophthalmic genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10415461","citation_count":16,"is_preprint":false},{"pmid":"29589282","id":"PMC_29589282","title":"Haploinsufficiency of SIX3 Abolishes Male Reproductive Behavior Through Disrupted Olfactory Development, and Impairs Female Fertility Through Disrupted GnRH Neuron Migration.","date":"2018","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/29589282","citation_count":16,"is_preprint":false},{"pmid":"23792023","id":"PMC_23792023","title":"Genomic code for Sox2 binding uncovers its regulatory role in Six3 activation in the forebrain.","date":"2013","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/23792023","citation_count":16,"is_preprint":false},{"pmid":"28643150","id":"PMC_28643150","title":"Epigenetically controlled Six3 expression regulates glioblastoma cell proliferation and invasion alongside modulating the activation levels of WNT pathway members.","date":"2017","source":"Journal of neuro-oncology","url":"https://pubmed.ncbi.nlm.nih.gov/28643150","citation_count":16,"is_preprint":false},{"pmid":"11173923","id":"PMC_11173923","title":"The orphan nuclear receptor NOR-1 interacts with the homeobox containing protein Six3.","date":"2001","source":"Developmental neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/11173923","citation_count":15,"is_preprint":false},{"pmid":"11554737","id":"PMC_11554737","title":"Regulation of the human SIX3 gene promoter.","date":"2001","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11554737","citation_count":15,"is_preprint":false},{"pmid":"17084678","id":"PMC_17084678","title":"Expression of Six3 Opposite Strand (Six3OS) during mouse embryonic development.","date":"2006","source":"Gene expression patterns : GEP","url":"https://pubmed.ncbi.nlm.nih.gov/17084678","citation_count":15,"is_preprint":false},{"pmid":"34021861","id":"PMC_34021861","title":"miR-4306 Suppresses Proliferation of Esophageal Squamous Cell Carcinoma Cell by Targeting SIX3.","date":"2021","source":"Cell biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/34021861","citation_count":14,"is_preprint":false},{"pmid":"26160900","id":"PMC_26160900","title":"Anteroposterior patterning of Drosophila ocelli requires an anti-repressor mechanism within the hh pathway mediated by the Six3 gene Optix.","date":"2015","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/26160900","citation_count":13,"is_preprint":false},{"pmid":"15523651","id":"PMC_15523651","title":"Functional characterization of SIX3 homeodomain mutations in holoprosencephaly: interaction with the nuclear receptor NR4A3/NOR1.","date":"2004","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/15523651","citation_count":12,"is_preprint":false},{"pmid":"27019633","id":"PMC_27019633","title":"Transcriptional Reactivation of OTX2, RX1 and SIX3 during Reprogramming Contributes to the Generation of RPE Cells from Human iPSCs.","date":"2016","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/27019633","citation_count":12,"is_preprint":false},{"pmid":"28670735","id":"PMC_28670735","title":"SIX3 deletions and incomplete penetrance in families affected by holoprosencephaly.","date":"2017","source":"Congenital anomalies","url":"https://pubmed.ncbi.nlm.nih.gov/28670735","citation_count":12,"is_preprint":false},{"pmid":"29736313","id":"PMC_29736313","title":"A novel long noncoding RNA lncWDR26 suppresses the growth and metastasis of hepatocellular carcinoma cells through interaction with SIX3.","date":"2018","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/29736313","citation_count":11,"is_preprint":false},{"pmid":"15559128","id":"PMC_15559128","title":"[Analysis of the expression pattern of regulatory genes Pax6, Prox1, and Six3 during regeneration of eye structures in the newt].","date":"2004","source":"Izvestiia Akademii nauk. Seriia biologicheskaia","url":"https://pubmed.ncbi.nlm.nih.gov/15559128","citation_count":11,"is_preprint":false},{"pmid":"34974160","id":"PMC_34974160","title":"Deletion of Six3 in post-proliferative neurons produces weakened SCN circadian output, improved metabolic function, and dwarfism in male mice.","date":"2021","source":"Molecular metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/34974160","citation_count":10,"is_preprint":false},{"pmid":"18771023","id":"PMC_18771023","title":"[Expression of regulatory genes Pax6, Otx2, Six3, and FGF2 during newt retina regeneration].","date":"2008","source":"Izvestiia Akademii nauk. Seriia biologicheskaia","url":"https://pubmed.ncbi.nlm.nih.gov/18771023","citation_count":10,"is_preprint":false},{"pmid":"20193042","id":"PMC_20193042","title":"Autoregulatory binding sites in the zebrafish six3a promoter region define a new recognition sequence for Six3 proteins.","date":"2010","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/20193042","citation_count":10,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":45546,"output_tokens":10046,"usd":0.143664},"stage2":{"model":"claude-opus-4-6","input_tokens":14024,"output_tokens":4074,"usd":0.257955},"total_usd":0.401619,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"Six3 is a murine homologue of the Drosophila sine oculis gene, encoding a homeodomain-containing transcription factor expressed in the anterior neural plate and developing eye; its expression is not affected by Pax6 loss-of-function (Small eye mutants), placing it in a parallel or independent pathway.\",\n      \"method\": \"Gene cloning, sequence analysis, chromosomal mapping, in situ hybridization in wild-type and Pax6 mutant embryos\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — foundational characterization paper, >500 citations, multiple orthogonal methods\",\n      \"pmids\": [\"8575305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Ectopic expression of mouse Six3 in medaka fish embryos is sufficient to promote ectopic lens formation, demonstrating that Six3 can trigger the genetic pathway leading to lens differentiation independently of retinal tissue.\",\n      \"method\": \"Ectopic RNA injection/overexpression in medaka fish embryos with histological and molecular marker analysis\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct gain-of-function with defined cellular phenotype, >100 citations\",\n      \"pmids\": [\"9025075\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mutations in the homeodomain of human SIX3 cause holoprosencephaly; at least four different homeodomain mutations are associated with HPE2 and are predicted to interfere with transcriptional activation, establishing SIX3 as the HPE2 gene.\",\n      \"method\": \"Positional cloning, mutational analysis in HPE patients, chromosomal mapping of translocation breakpoints\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human genetics with multiple independent mutations, >290 citations\",\n      \"pmids\": [\"10369266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Six3 overexpression in medaka fish embryos causes ectopic Pax6 and Rx2 expression in midbrain and cerebellum, leading to formation of ectopic retinal primordia; injected mouse Six3 also initiates ectopic endogenous medaka Six3 expression, revealing an autoregulatory feedback loop.\",\n      \"method\": \"RNA injection/overexpression in medaka fish embryos with molecular marker analysis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function with defined molecular and cellular phenotypes, >180 citations\",\n      \"pmids\": [\"10090721\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Six3 functions as a Groucho-dependent transcriptional repressor in eye and forebrain formation; it contains eh1-related motifs that mediate interaction with the Groucho corepressor Grg3; point mutations in the eh1 motifs reduce both forebrain-enlarging activities and interaction with Grg3 in zebrafish.\",\n      \"method\": \"Yeast two-hybrid, dominant activator/repressor overexpression in zebrafish, site-directed mutagenesis, in vivo phenotypic analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including mutagenesis and in vivo rescue, >140 citations\",\n      \"pmids\": [\"11401394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Six3 acts as a transcriptional repressor of the gamma-crystallin (CRYGF) promoter, reducing its activity to ~10% of basal, and acts antagonistically to Prox1 activator at the CRYGD/e/f promoters; a Six3-responsive element was mapped between -101 and -123 of the gammaF-crystallin promoter.\",\n      \"method\": \"Cell transfection reporter assays, randomly mutated promoter fragment analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional reporter assays with defined binding element, single lab\",\n      \"pmids\": [\"11139622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Six3 interacts with Groucho-related corepressors Grg4 and Grg5 via a conserved phenylalanine in an eh1-like motif in the Six domain of Six3; this interaction was validated by co-immunoprecipitation; Six3 binds a specific DNA motif and acts as a potent transcriptional repressor through this interaction; disruption of the Groucho interaction abolishes Six3-dependent auto-repression and eye/lens developmental functions in vivo.\",\n      \"method\": \"Co-immunoprecipitation from cell lines, DNA-binding PCR assay, in vivo retroviral overexpression in rat retina, in ovo electroporation in chick, site-directed mutagenesis\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — reciprocal Co-IP, mutagenesis, in vivo functional validation with multiple species, >170 citations\",\n      \"pmids\": [\"12050133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Six3 and Pax6 mutually activate each other's expression in the developing lens; Six3 binds regulatory sequences of the Pax6 gene and Pax6 binds regulatory sequences of Six3; lens-specific expression of Six3 rescues the Pax6 haploinsufficient lens phenotype via cell proliferation and activation of the PDGF-alpha-R/cyclin D1 signaling pathway.\",\n      \"method\": \"In vitro binding assays, transgenic rescue experiments, pathway analysis\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro binding + transgenic rescue + pathway analysis, multiple orthogonal methods\",\n      \"pmids\": [\"12072567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Six3 is a direct negative regulator of Wnt1 expression in the anterior neuroectoderm; in Six3-null mice, Wnt1 expression is rostrally expanded; Six3 binds the Wnt1 locus in vivo and in vitro DNA-binding assays; ectopic Six3 in chick and fish embryos represses Wnt1; phenotypic rescue of headless/tcf3 zebrafish by mouse Six3 demonstrates Six3 acts upstream of Wnt signaling to specify forebrain fate.\",\n      \"method\": \"Six3 knockout mouse analysis, in vivo and in vitro DNA-binding assays, ectopic expression in chick and zebrafish, genetic epistasis (headless/tcf3 rescue)\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — KO phenotype + direct DNA binding + genetic epistasis in multiple model systems, >380 citations\",\n      \"pmids\": [\"12569128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The Six domain of Six3 (and Six6) strongly interacts with the QD domain of TLE1 and AES (Groucho family members); Six3 additionally interacts with TLE proteins via the WDR domain; gain-of-function in medaka shows synergistic activity between Six3/Six6 and TLE1 in expanding the eye field; AES abrogates Six3/Six6 overexpression phenotypes.\",\n      \"method\": \"Yeast two-hybrid screen, biochemical and mutational analysis, gain-of-function in medaka fish\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Y2H plus biochemical domain mapping plus in vivo functional synergy, >110 citations\",\n      \"pmids\": [\"12441302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Six3 directly binds to geminin (a DNA replication-inhibitor/Cdt1 sequestrator) and competes with Cdt1 for geminin binding, thereby promoting cell proliferation without transcription; overexpression of geminin in medaka phenocopies Six3 inactivation (forebrain/eye defects), and these defects are rescued by Six3; loss of geminin promotes retinal precursor proliferation, potentiating Six3 gain-of-function.\",\n      \"method\": \"Yeast two-hybrid screen, direct protein binding competition assay, overexpression and loss-of-function in medaka fish, genetic rescue experiments\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — Y2H + biochemical competition assay + genetic rescue in vivo, >200 citations\",\n      \"pmids\": [\"14973488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Six3 expands the anterior neural plate partly through transcriptional regulation of cell cycle regulators cyclinD1 and p27Xic1 and anti-neurogenic genes Zic2 and Xhairy2; it can also expand the neural plate independently of the cell cycle by repressing Bmp4 expression in adjacent ectoderm; Six3 cannot alone induce neural tissue in animal caps but can do so in combination with Otx2.\",\n      \"method\": \"Ectopic expression in Xenopus and zebrafish, cell cycle inhibitor treatment, Bmp4 expression analysis, chordino mutant rescue\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple in vivo gain-of-function and genetic epistasis experiments across two model organisms\",\n      \"pmids\": [\"15843413\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Lhx2 mediates an alternative/parallel pathway for cellular proliferation in the developing forebrain downstream of Six3; head-specific activation of Lhx2 completely rescues the telencephalon size reduction in six3 morphant zebrafish, whereas ectopic Six3b cannot rescue lhx2 knockdown, placing Lhx2 downstream of Six3 in this pathway.\",\n      \"method\": \"Antisense morpholino knockdown, caged-mRNA photoactivation in zebrafish, genetic epistasis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with clean KD/OE and defined phenotypic readout, single lab\",\n      \"pmids\": [\"16226737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Six3 directly activates Pax6 and Sox2 expression in the presumptive lens ectoderm; conditional deletion of Six3 in the lens ectoderm causes loss of Pax6 and Sox2 expression and failure of lens induction; ChIP, EMSA, and luciferase reporter assays confirm direct binding and activation; misexpression in chick promotes ectopic ectodermal Pax6 expression domain.\",\n      \"method\": \"Conditional knockout in mouse, ChIP, electrophoretic mobility shift assay (EMSA), luciferase reporter assay, chick misexpression\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — conditional KO + ChIP + EMSA + reporter assay + in vivo misexpression, multiple orthogonal methods\",\n      \"pmids\": [\"17066077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MTA1 physically interacts with Six3 chromatin in a histone deacetylase-dependent manner, leading to transcriptional suppression of the Six3 gene; MTA1 is also a Six3-interacting corepressor contributing to self-negative regulation of Six3; Six3's homeodomain interacts with specific DNA elements in the rhodopsin promoter to stimulate rhodopsin transcription; Six3 cooperates with Crx or NRL in stimulating rhodopsin-luc transcription; HPE-associated Six3 homeodomain deletion mutations cannot bind rhodopsin DNA or stimulate its transcription.\",\n      \"method\": \"ChIP, Co-IP, gain/loss-of-function in MTA1-null mice and retinal ganglion cells, luciferase reporter assays\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — ChIP + Co-IP + in vivo KO + reporter assays with mutagenesis validation\",\n      \"pmids\": [\"17666527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Six3 represses Wnt1 transcription; in Six3-null mice, Wnt1 is anteriorly expanded causing progressive caudalization of the diencephalon; analysis of Six3;Wnt1 double-null mice demonstrates that Six3-mediated repression of Wnt1 is necessary for formation of the rostral diencephalon, and that Six3 activity is required for telencephalon formation.\",\n      \"method\": \"Six3 knockout, Six3;Wnt1 double knockout genetic epistasis, developmental staging analysis\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — double KO genetic epistasis with defined molecular phenotype\",\n      \"pmids\": [\"18094027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Six3 acts in the neuroectoderm to establish a prepattern of bilateral repression of Nodal activity in the dorsal diencephalon; reduction of Six3 function causes brain-specific deregulation of Nodal pathway activity resulting in epithalamic laterality defects; epistasis experiments position Six3 upstream of Nodal signaling in establishing brain left-right asymmetry.\",\n      \"method\": \"Zebrafish loss-of-function (morpholino), misexpression, genetic epistasis experiments\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — morpholino KD + misexpression + genetic epistasis, defined molecular pathway\",\n      \"pmids\": [\"17678854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Six3 directly binds and activates the Shh brain enhancer-2 (SBE2), a remote forebrain enhancer located 460 kb upstream of SHH; HPE-causing SIX3 alterations fail to bind and activate SBE2; identified via DNA affinity-capture assay screening of SBE2 sequence.\",\n      \"method\": \"DNA affinity-capture assay, transgenic mouse enhancer assay, direct DNA-binding assay with HPE mutant proteins\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — DNA affinity capture + transgenic enhancer validation + mutagenesis, >140 citations\",\n      \"pmids\": [\"18836447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Six3 haploinsufficiency (deletion of one Six3 allele or replacement with HPE-associated mutant alleles) is sufficient to recapitulate human HPE in mice; Shh is a direct target of Six3 in the rostral diencephalon ventral midline (RDVM); reduced Six3 fails to activate Shh in the RDVM, demonstrating a direct regulatory relationship and a crossregulatory loop between Shh and Six3 in the ventral forebrain.\",\n      \"method\": \"Six3 haploinsufficiency mouse models, ChIP for Six3 binding to Shh locus, zebrafish functional assays\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mouse genetic model + ChIP + zebrafish assay, multiple orthogonal methods, >130 citations\",\n      \"pmids\": [\"18694563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"HPE-associated SIX3 mutations are loss-of-function alleles (89% confirmed in zebrafish assays); disease-associated mutations in the Groucho-binding eh1-like motif decrease Six3 function in all assays, confirming that Six3-Groucho co-repressor interaction is essential for human SIX3 activity and HPE pathogenesis; truncated Six3 versions lacking the homeodomain retain partial function.\",\n      \"method\": \"Zebrafish gain-of-function and loss-of-function assays for 46 distinct SIX3 mutations, structure-function analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — systematic functional analysis of 46 mutations with multiple assay readouts\",\n      \"pmids\": [\"18791198\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Six3 directly represses Wnt8b expression in the developing neuroretina; conditional deletion of Six3 causes ectopic Wnt8b expression which is sufficient to suppress neuroretina specification; ChIP identified Six3-responsive elements in the Wnt8b locus; transgenic ectopic Wnt8b expression phenocopies Six3 deletion in blocking neuroretina specification.\",\n      \"method\": \"Conditional Six3 knockout in mouse, ChIP, transgenic Wnt8b overexpression, comparative molecular analysis\",\n      \"journal\": \"Journal of Clinical Investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — conditional KO + ChIP + transgenic phenocopy, multiple orthogonal methods\",\n      \"pmids\": [\"20890044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MTA1s and MTA1 physically interact with Six3 chromatin and inhibit Six3 transcription in a histone deacetylase-dependent manner; this allows derepression of Wnt1 transcription (which Six3 normally represses); in MTA1/MTA1s null cells, Six3 is upregulated and Six3 corepressor complex recruitment to the Wnt1 promoter is increased.\",\n      \"method\": \"ChIP, gain/loss-of-function (knockdown and knockout), multiple model systems including MEFs and mammary glands\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — ChIP + KO model + multiple cell systems\",\n      \"pmids\": [\"20682799\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Six3OS, a long noncoding RNA transcribed from the distal promoter region of Six3, binds directly to Ezh2 and Eya family members, acting as a molecular scaffold to recruit histone modification enzymes to Six3 target genes, thereby modulating Six3 activity during retinal cell specification without affecting Six3 expression levels.\",\n      \"method\": \"Overexpression and knockdown analysis, direct binding assays (Six3OS-Ezh2 and Six3OS-Eya interactions), retinal cell specification assays\",\n      \"journal\": \"Neural development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding + functional loss/gain-of-function + mechanistic scaffold characterization\",\n      \"pmids\": [\"21936910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Six3 is required for ependymal cell maturation; in its absence, ependymal cells fail to suppress radial glia characteristics, resulting in defective lateral wall, abnormal neuroblast migration and differentiation, and hydrocephaly; Six3 is expressed in ependymal cells during formation of the lateral wall of the lateral ventricles.\",\n      \"method\": \"Six3 conditional knockout in mouse, cellular marker analysis, localization studies\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with specific cellular and tissue-level phenotypic readouts\",\n      \"pmids\": [\"22071110\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Six3 promotes ventral telencephalic fates by transiently regulating foxg1a expression and repressing the Wnt/β-catenin pathway; Six3 cooperates with Hedgehog signaling to specify ventral telencephalon, with an Hh-independent role in isl1-positive (but not nkx2.1b-positive) cells.\",\n      \"method\": \"Zebrafish six3b;six7 double morphant analysis, genetic epistasis with Hedgehog pathway, overexpression experiments\",\n      \"journal\": \"Development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis and KD in zebrafish, single lab\",\n      \"pmids\": [\"22736245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Sox2 directly regulates a long-range forebrain enhancer to activate Six3 expression in the rostral diencephalon; biochemical (ChIP) and genetic evidence indicate a direct regulatory link between Sox2 and Six3 during forebrain development.\",\n      \"method\": \"Genomic ChIP-based identification, in vivo transgenic reporter assay, biochemical and genetic validation\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP + transgenic enhancer assay + genetic evidence, single lab\",\n      \"pmids\": [\"23792023\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Six3 dosage-dependently determines HPE phenotype severity in mice: semilobar HPE results from severe downregulation of Shh expression in the rostral diencephalon ventral midline, while alobar HPE results from downregulation of Foxg1 expression in the anterior neural ectoderm; in vivo activation of Shh signaling rescues the semilobar but not alobar phenotype, establishing two distinct downstream pathways.\",\n      \"method\": \"Novel hypomorphic Six3 allele mouse model, Shh pathway activation rescue, molecular phenotyping\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — hypomorphic allele series + genetic rescue experiment distinguishing two pathways\",\n      \"pmids\": [\"27770010\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Six3 directly represses R-spondin 2 (Rspo2) expression during neuroretina differentiation; transient ectopic expression of Rspo2 in the anterior neural plate of transgenic mice is sufficient to inhibit neuroretina differentiation; Six3-null cells exert a non-cell-autonomous repressive effect on optic vesicle formation and neuroretina differentiation in chimeric eye organoids.\",\n      \"method\": \"Eye organoid system using ESC/iPSC-derived optic vesicles, Six3-/- iPSC generation, conditional null ESCs, transgenic mouse experiments, chimeric organoid assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — organoid reconstitution + transgenic in vivo validation + chimeric analysis, multiple orthogonal methods\",\n      \"pmids\": [\"29117559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Six3 in a small population of anteroventral optic pit/vesicle progenitors at E8.5 is required for neuroretinal specification by repressing Wnt8b and maintaining Fgf8/MAPK signaling; lineage tracing showed Six3-Cre positive progenitors contribute to neuroretina and optic stalk but not RPE; Six3 deletion in these cells causes the progenitors to be lost and RPE to derive from Six3-Cre-negative cells.\",\n      \"method\": \"Cre-mediated lineage tracing in wild-type and Six3-deficient mice, conditional deletion, molecular signaling pathway analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — lineage tracing + conditional KO + signaling analysis, multiple orthogonal approaches\",\n      \"pmids\": [\"28579317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SP8 and SP9 transcription factors drive expression of Six3 in a spatially restricted domain of the LGE subventricular zone; ChIP-Seq reveals SP9 directly binds the promoter and a putative enhancer of Six3; conditional deletion of Six3 prevents formation of most D2 MSNs, phenocopying Sp8/9 mutants, placing Six3 downstream of SP8/SP9 in a transcription pathway for D2 MSN production.\",\n      \"method\": \"Conditional deletion of Sp8, Sp9, and Six3 in mice, ChIP-Seq for SP9 binding to Six3 locus, neuronal subtype marker analysis\",\n      \"journal\": \"Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — ChIP-Seq + conditional KO epistasis + phenotypic characterization\",\n      \"pmids\": [\"29967281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SIX3 forms a complex with LSD1/NuRD(MTA3); affinity purification and mass spectrometry identified this complex; ChIP-on-chip identified WNT1 and FOXC2 as genomic targets of the SIX3/LSD1/NuRD(MTA3) complex, which inhibits carcinogenesis and metastasis in breast cancer cells.\",\n      \"method\": \"Affinity purification/mass spectrometry, ChIP-on-chip, functional tumor assays\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — AP-MS complex identification + ChIP-on-chip target identification\",\n      \"pmids\": [\"29463994\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Six3 and Six6 are jointly required for maintenance of multipotent neuroretinal progenitors by suppressing Wnt/β-catenin signaling and promoting retinogenic factors; the double KO (DKO) reveals a functional redundancy: neither single KO shows the DKO phenotype, including ectopic upregulation of Wnt3a, Fzd1, CM markers, and loss of Sox2, Notch1, and Otx2.\",\n      \"method\": \"Six3 and Six6 double conditional knockout in mice, Wnt signaling stimulation experiments, molecular marker analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — double KO genetic analysis + signaling pathway manipulation, orthogonal approaches\",\n      \"pmids\": [\"30485816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"EGFR activation induces DNA methylation of the SIX3 promoter through MAPK pathway; ERK binds ZNF263, abrogating its ubiquitination and stabilizing it; ZNF263 binds the SIX3 core promoter and recruits KAP1/HATS/DNMT corepressor complex, inducing transcriptional silencing of SIX3 through H3K27me3 and DNA methylation.\",\n      \"method\": \"Signaling pathway manipulation, Co-IP, ChIP, promoter methylation analysis, epistasis experiments\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple biochemical methods establishing epigenetic silencing mechanism, single lab\",\n      \"pmids\": [\"32051553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIM27 ubiquitinates and degrades SIX3 protein; TRIM27 acts as an E3 ubiquitin ligase for SIX3, leading to activation of Wnt/β-catenin signaling (which SIX3 normally represses) and promotion of NSCLC cell proliferation and metastasis.\",\n      \"method\": \"Co-IP, ubiquitination assays, knockdown/overexpression experiments in lung cancer cells and tissue analysis\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct ubiquitination assay + functional rescue, single lab\",\n      \"pmids\": [\"33264103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Six3 is required for the differentiation (but not proliferation) of D2-type medium spiny neuron precursor cells in the LGE; conditional overexpression of Six3 promotes LGE precursor differentiation; in the absence of Six3, abnormally differentiated D2 MSNs are eliminated by apoptosis postnatally.\",\n      \"method\": \"Conditional Six3 knockout and overexpression in mice, cell proliferation/apoptosis assays, neuronal marker analysis\",\n      \"journal\": \"Neuroscience bulletin\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO + overexpression with defined cellular phenotype, single lab\",\n      \"pmids\": [\"34014554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SIX3 suppression in human adult pancreatic islets impairs insulin secretion; SIX3 loss leads to inappropriate expression of fetal β-cell genes, adult α-cell genes, and non-β-cell genes, indicating SIX3 maintains developmental fate of mature β cells; chromatin accessibility studies identified genes directly regulated by SIX3.\",\n      \"method\": \"shRNA-mediated knockdown in human islets, transcriptome analysis, chromatin accessibility (ATAC-seq), functional insulin secretion assay\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human tissue KD + transcriptome + chromatin accessibility + functional assay, multiple orthogonal methods\",\n      \"pmids\": [\"33446570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The orphan nuclear receptor NOR-1 interacts with Six3 in vitro and in yeast; the interaction requires the DNA binding and AF2 domains of NOR-1; Six3 has a negative effect on NOR-1 transactivation through the NBRE response element in a dose-dependent manner.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro pull-down, cotransfection reporter assays\",\n      \"journal\": \"Developmental neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Y2H + in vitro pull-down + reporter assay, single lab\",\n      \"pmids\": [\"11173923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Six3 acts as a coactivator of nuclear receptor NOR-1 and as a corepressor of the fusion protein EWS/NOR-1; Six3 binds the DNA-binding domain of NOR-1 and the EWS domain of EWS/NOR-1 in GST pull-down assays; Six3 homeodomain is required for these interactions; in vivo interaction confirmed by mammalian two-hybrid in immortalized chondrocytes.\",\n      \"method\": \"RT-PCR in EMC tumors, GST pull-down assay, mammalian two-hybrid, cotransfection reporter assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — GST pull-down + mammalian two-hybrid + reporter assay with domain mapping\",\n      \"pmids\": [\"12543801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Six3 bHLH co-factor screen identified ATH5, ATH3, NEUROD, and ASH1 as proteins that interact specifically with XSix3; the bHLH domain of NEUROD interacts with the SIX domain of XSix3, defining a new interaction interface.\",\n      \"method\": \"Yeast two-hybrid screen, biochemical domain-mapping analysis\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — Y2H and domain mapping only, no in vivo functional follow-up in this paper\",\n      \"pmids\": [\"12204251\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"An in vitro protein-protein interaction is detected between Six3 and Eya1; Six3 expression in the pre-placode lens ectoderm is initially Pax6-independent but subsequently both its expression and nuclear localization become Pax6-dependent.\",\n      \"method\": \"In vitro protein-protein interaction assay, immunohistochemistry in Pax6 mutant mice, nuclear localization analysis\",\n      \"journal\": \"Gene expression patterns\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single in vitro interaction assay with limited functional follow-up\",\n      \"pmids\": [\"16024294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"EYA4 is co-immunoprecipitated with SIX3; EYA4 protein is recruited to the nucleus by SIX3; EYA4 cooperates with SIX3 in reporter gene assays as a transcriptional coactivator, demonstrating physical and functional association between EYA4 and SIX3.\",\n      \"method\": \"Co-immunoprecipitation, confocal microscopy for subcellular localization, reporter gene assays\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP + localization + reporter assay, single lab\",\n      \"pmids\": [\"19606496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Six3 defines a novel DNA recognition sequence (TAATGTC) for its homeodomain; this is distinct from the common Six family recognition sequence (TGATAC); in vitro binding to TAATGTC and TGATAC sites shows similar affinities suggesting two distinct DNA-binding modes; ChIP in zebrafish embryos confirmed Six3a binding to promoter fragments containing the TAATGTC motif, which is involved in autoregulation.\",\n      \"method\": \"In vitro binding affinity analysis with single-nucleotide substitutions, transient reporter assays in zebrafish embryos, ChIP in zebrafish\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro binding + ChIP + in vivo reporter, defines new recognition sequence\",\n      \"pmids\": [\"20193042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"SIX3 represses transcription of GnRH receptor (GnRHR) and the common α-subunit (Cga) genes in immature gonadotrope cell lines; SIX3 and SIX6 can functionally compensate for each other in gonadotrope gene regulation; SIX6 repression requires interaction with TLE corepressor proteins and competition for DNA-binding sites with Pitx1.\",\n      \"method\": \"siRNA knockdown in gonadotrope cell lines, Six6 knockout mouse analysis, reporter and binding assays\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD in cell lines + KO mouse + reporter assays, single lab\",\n      \"pmids\": [\"25915183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SIX3 directly represses transcription of aurora kinase A (AURKA) and aurora kinase B (AURKB) in astrocytoma cells in a dose-dependent manner; ChIP confirmed SIX3 binding to AURKA and AURKB promoter regions; SIX3 increases p53 activity at the post-translational level through negative regulation of AURKA/AURKB; AURKA and AURKB interact to stabilize each other, an interaction not affected by SIX3 overexpression.\",\n      \"method\": \"ChIP, luciferase reporter assay, Co-IP for AURKA-AURKB interaction, flow cytometry, intracranial xenograft\",\n      \"journal\": \"Journal of hematology & oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP + reporter assay + Co-IP + in vivo tumor model\",\n      \"pmids\": [\"28595628\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SIX3 is a homeodomain transcription factor that functions primarily as a Groucho/TLE-dependent transcriptional repressor (via an eh1-like motif in its Six domain) of Wnt1, Wnt8b, Shh-regulatory enhancers, and other target genes in the anterior neural plate and developing eye, while also acting as a direct transcriptional activator of Pax6, Sox2, Shh (via SBE2), and rhodopsin; it promotes cell proliferation non-transcriptionally by competing with Cdt1 to bind geminin, and its activity is modulated by interactions with multiple co-factors including Groucho/TLE family members, EYA family members, geminin, MTA1 (which epigenetically silences Six3 via HDAC-dependent chromatin remodeling), and the lncRNA Six3OS (which scaffolds Ezh2 and Eya to Six3 target genes), with haploinsufficiency causing holoprosencephaly through failure to activate Shh in the rostral diencephalon ventral midline.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SIX3 is a homeodomain transcription factor that orchestrates anterior neural plate patterning, eye development, and forebrain specification by functioning as both a transcriptional repressor and activator depending on cofactor context. As a repressor, SIX3 recruits Groucho/TLE corepressors via an eh1-like motif in its Six domain to directly silence Wnt1, Wnt8b, Rspo2, and Bmp4, thereby protecting anterior neuroectoderm from posteriorizing signals and enabling neuroretinal and telencephalic specification [PMID:12050133, PMID:12569128, PMID:20890044, PMID:29117559]; as an activator, it directly binds and stimulates transcription of Pax6, Sox2, Shh (via the remote SBE2 enhancer), and rhodopsin, often cooperating with cofactors such as Crx, NRL, and EYA family members [PMID:17066077, PMID:18836447, PMID:17666527]. SIX3 also promotes cell proliferation non-transcriptionally by competing with Cdt1 for geminin binding, thereby relieving replication licensing inhibition [PMID:14973488]. Haploinsufficiency of SIX3 causes holoprosencephaly (HPE2) in humans and mice through failure to activate Shh in the rostral diencephalon ventral midline, with disease severity correlating with dosage-dependent effects on Shh and Foxg1 expression [PMID:10369266, PMID:18694563, PMID:27770010].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Identification of Six3 as a vertebrate homologue of Drosophila sine oculis established that a homeodomain transcription factor with anterior-restricted expression exists independently of the Pax6 pathway, opening the question of its specific function in head development.\",\n      \"evidence\": \"Gene cloning, sequence analysis, in situ hybridization in wild-type and Pax6 mutant mouse embryos\",\n      \"pmids\": [\"8575305\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No target genes identified\", \"No loss-of-function phenotype characterized\", \"Relationship to other anterior transcription factors undefined\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Demonstrating that ectopic Six3 expression induces lens formation and retinal primordia in fish established Six3 as a sufficient master regulator of eye field identity, not merely a marker.\",\n      \"evidence\": \"Ectopic RNA injection in medaka with histological and marker analysis\",\n      \"pmids\": [\"9025075\", \"10090721\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No loss-of-function data\", \"Target gene cascades downstream of Six3 unknown\", \"Mechanism of action (activator vs. repressor) unresolved\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Discovery that homeodomain mutations in human SIX3 cause holoprosencephaly (HPE2) established that SIX3 is essential for forebrain midline development and linked its transcriptional activity to a major human congenital malformation.\",\n      \"evidence\": \"Positional cloning and mutational analysis in HPE patient families\",\n      \"pmids\": [\"10369266\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct transcriptional targets in forebrain unknown\", \"Mechanism by which mutations cause HPE unresolved\", \"Animal model of haploinsufficiency not yet available\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying Six3 as a Groucho/TLE-dependent transcriptional repressor that uses an eh1-like motif resolved the long-standing question of whether Six3 acts as an activator or repressor, revealing that its primary developmental function in forebrain expansion requires corepressor recruitment.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, site-directed mutagenesis of eh1 motif, zebrafish overexpression phenotyping\",\n      \"pmids\": [\"11401394\", \"12050133\", \"12441302\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct genomic targets of repression not identified by ChIP\", \"Whether Six3 also has activator functions remained unclear\", \"Role of individual Groucho/TLE family members not distinguished in vivo\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Six3-null mouse analysis revealed that Six3 directly binds and represses Wnt1 transcription in the anterior neuroectoderm, and genetic epistasis showed Six3 acts upstream of Wnt signaling, establishing the first direct target gene and the core mechanism by which Six3 protects forebrain identity.\",\n      \"evidence\": \"Six3 knockout mouse, in vivo/in vitro DNA-binding assays, ectopic expression in chick/zebrafish, headless/tcf3 rescue\",\n      \"pmids\": [\"12569128\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Wnt1 is the sole critical target or one of several Wnt genes repressed was unknown\", \"The Six3-Shh regulatory relationship not yet characterized\", \"Mechanism of anterior-restricted Six3 expression unresolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Discovery that Six3 binds geminin and competes with Cdt1 for geminin binding revealed a non-transcriptional mechanism for promoting cell proliferation, explaining how Six3 can drive progenitor expansion independently of its DNA-binding activity.\",\n      \"evidence\": \"Yeast two-hybrid, direct protein competition assay, genetic rescue in medaka\",\n      \"pmids\": [\"14973488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of transcriptional vs. geminin-mediated proliferation not quantified\", \"Whether geminin interaction occurs in mammalian forebrain progenitors not confirmed in vivo\", \"Structural basis of competitive binding unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Conditional deletion of Six3 in lens ectoderm combined with ChIP and EMSA demonstrated that Six3 directly activates Pax6 and Sox2, establishing that Six3 functions as a transcriptional activator for key lens-induction genes, not solely as a repressor.\",\n      \"evidence\": \"Conditional KO in mouse, ChIP, EMSA, luciferase reporter, chick misexpression\",\n      \"pmids\": [\"17066077\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cofactors converting Six3 from repressor to activator mode not identified\", \"Whether Six3 activator function is relevant in forebrain (not just lens) undetermined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identifying MTA1 as a cofactor that epigenetically silences Six3 itself via HDAC-dependent chromatin remodeling, and demonstrating that Six3 homeodomain directly activates rhodopsin transcription (with HPE mutations ablating this binding), established a regulatory feedback on Six3 levels and extended its activator role to post-mitotic photoreceptors.\",\n      \"evidence\": \"ChIP, Co-IP, MTA1-null mouse analysis, luciferase reporter with HPE mutant proteins\",\n      \"pmids\": [\"17666527\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MTA1-mediated silencing of Six3 is relevant in forebrain HPE pathogenesis unknown\", \"Full repertoire of Six3 activator targets in retina not catalogued\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that Six3 directly binds and activates the remote Shh brain enhancer SBE2, and that Six3 haploinsufficiency recapitulates human HPE through failure to activate Shh in the rostral diencephalon ventral midline, closed the mechanistic gap between SIX3 mutations and HPE pathogenesis via a direct Six3→Shh regulatory axis.\",\n      \"evidence\": \"DNA affinity-capture assay, transgenic enhancer assay, ChIP at Shh locus, Six3 haploinsufficient mouse models, functional analysis of 46 HPE mutations in zebrafish\",\n      \"pmids\": [\"18836447\", \"18694563\", \"18791198\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the same transcription factor switches between repression (Wnt1) and activation (Shh) mechanistically unresolved\", \"Modifier genes explaining variable HPE expressivity not identified\", \"Whether all HPE mutations act through SBE2 or through additional enhancers unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"ChIP-validated direct repression of Wnt8b by Six3 in the neuroretina, with transgenic Wnt8b phenocopying Six3 loss, established a second Wnt target through which Six3 specifies neuroretinal fate distinct from its Wnt1-mediated forebrain function.\",\n      \"evidence\": \"Conditional Six3 KO in mouse, ChIP, transgenic Wnt8b overexpression\",\n      \"pmids\": [\"20890044\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Wnt8b repression and Wnt1 repression employ the same corepressor complexes untested\", \"Genome-wide catalog of Six3-bound Wnt pathway genes absent\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that the lncRNA Six3OS scaffolds Ezh2 and Eya to Six3 target genes revealed an epigenetic layer of Six3 regulation operating at the chromatin level, modulating target gene specificity during retinal differentiation without affecting Six3 expression itself.\",\n      \"evidence\": \"Overexpression/knockdown, direct binding assays for Six3OS-Ezh2 and Six3OS-Eya interactions, retinal specification assays\",\n      \"pmids\": [\"21936910\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific genomic loci where Six3OS acts not mapped\", \"Whether Six3OS is required in vivo for eye development not tested by genetic deletion\", \"Stoichiometry of the Six3/Six3OS/Ezh2/Eya complex uncharacterized\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"A hypomorphic allele series showed that Six3 dosage determines HPE severity through two distinct downstream pathways—Shh for semilobar and Foxg1 for alobar HPE—explaining the clinical spectrum of SIX3-associated HPE.\",\n      \"evidence\": \"Novel hypomorphic Six3 allele mouse model, Shh pathway activation rescue, molecular phenotyping\",\n      \"pmids\": [\"27770010\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Six3 directly regulates Foxg1 or acts indirectly not resolved\", \"Therapeutic implications of Shh rescue for semilobar HPE not explored\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identification of Rspo2 as a direct Six3 target repressed during neuroretina differentiation, with chimeric organoid experiments revealing non-cell-autonomous effects of Six3-null cells, extended the model to include Wnt-potentiating ligands and demonstrated organoid-based reconstitution of Six3 function.\",\n      \"evidence\": \"ESC/iPSC-derived eye organoids, Six3-null iPSCs, chimeric organoid assay, transgenic mice\",\n      \"pmids\": [\"29117559\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the non-cell-autonomous signal from Six3-null cells unknown\", \"Whether Rspo2 derepression alone accounts for the organoid phenotype untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Affinity purification identified a SIX3/LSD1/NuRD(MTA3) complex and ChIP-on-chip mapped its genomic targets including WNT1, providing a biochemical framework for how Six3 recruits histone demethylase/deacetylase machinery to achieve transcriptional repression at specific loci.\",\n      \"evidence\": \"AP-MS, ChIP-on-chip, functional tumor assays in breast cancer cells\",\n      \"pmids\": [\"29463994\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the LSD1/NuRD(MTA3) complex operates in developing forebrain or only in cancer cells not established\", \"Genome-wide overlap with Groucho/TLE-dependent repression untested\", \"Structural basis of the SIX3-LSD1-NuRD interaction unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that SIX3 knockdown in human adult pancreatic islets impairs insulin secretion and derepresses fetal/non-β-cell gene programs extended Six3 function beyond development to maintenance of mature cell identity in an endocrine context.\",\n      \"evidence\": \"shRNA knockdown in human islets, RNA-seq, ATAC-seq, insulin secretion assay\",\n      \"pmids\": [\"33446570\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct SIX3 target genes in β-cells not fully distinguished from indirect effects\", \"Whether SIX3 loss contributes to type 2 diabetes pathogenesis in humans unknown\", \"Cofactor complex used by SIX3 in β-cells not characterized\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include: (1) the structural and cofactor basis determining whether Six3 acts as a repressor or activator at specific loci; (2) a genome-wide map of direct Six3 binding sites across developmental stages; (3) the in vivo significance of the geminin interaction in mammalian forebrain progenitors; and (4) whether SIX3-based regulatory circuits are therapeutically targetable in HPE or diabetes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal structure of Six3 in complex with DNA or cofactors\", \"Genome-wide ChIP-seq across developmental time points lacking for most tissues\", \"In vivo functional significance of many reported protein interactions (NOR-1, bHLH factors) unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 5, 6, 8, 13, 17, 41]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [4, 5, 6, 8, 13, 14, 17, 20, 43]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 13, 14, 40]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [1, 3, 8, 11, 13, 15, 18, 20, 26, 27, 28, 29]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 15, 16, 20, 24, 31]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [4, 5, 6, 13, 14, 17, 43]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [2, 18, 19, 26]}\n    ],\n    \"complexes\": [\n      \"SIX3/Groucho(TLE) corepressor complex\",\n      \"SIX3/LSD1/NuRD(MTA3) complex\",\n      \"SIX3/geminin complex\"\n    ],\n    \"partners\": [\n      \"TLE1\",\n      \"GRG5\",\n      \"GMNN\",\n      \"MTA1\",\n      \"EYA1\",\n      \"EYA4\",\n      \"PAX6\",\n      \"LSD1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}