Affinage

PITX1

Pituitary homeobox 1 · UniProt P78337

Length
314 aa
Mass
34.1 kDa
Annotated
2026-04-28
100 papers in source corpus 43 papers cited in narrative 43 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PITX1 is a bicoid-related homeodomain transcription factor that functions as a master regulator of hindlimb identity, pituitary gene expression, tumor suppression, and innate immune gene modulation. In limb development, PITX1 directly activates Tbx4, HoxC10, HoxC11, Sox9, and Six1 to specify hindlimb morphology and drive chondrogenesis and myogenesis, with its tissue-restricted expression controlled by dedicated enhancers (PelA, PelB, Pen) whose deletion causes pelvic reduction and clubfoot (PMID:10049363, PMID:23201014, PMID:29273440, PMID:34903763). In the pituitary, PITX1 activates POMC, LHβ, and other hormone gene promoters through synergistic physical interactions with Pit-1, SF-1, and Egr-1, while in cancer contexts it suppresses RAS signaling by transcriptionally activating RASAL1, directly activates p53 transcription, and represses hTERT in cooperation with ZCCHC10 (PMID:8675014, PMID:9514159, PMID:15960973, PMID:17762884, PMID:21300782). PITX1 protein stability is regulated by PTP1B-mediated dephosphorylation at Y160/Y175/Y179 and its translation is suppressed by miR-19b and the RHAU helicase through 3′UTR-dependent mechanisms (PMID:26840794, PMID:25643913, PMID:24369427). Dominant-negative mutations in the PITX1 homeodomain and haploinsufficiency cause autosomal dominant lower-limb malformations including clubfoot in humans and mice (PMID:18950742, PMID:21775501).

Mechanistic history

Synthesis pass · year-by-year structured walk · 19 steps
  1. 1996 High

    Identification of PITX1 as a bicoid-class homeodomain factor that binds and activates the POMC promoter in pituitary cells, and physically synergizes with Pit-1, established the founding molecular activity and first partnership for this transcription factor.

    Evidence Cloning from AtT-20 cells, DNA-binding assays, reporter assays, interaction-based cloning with Pit-1

    PMID:8675014 PMID:8755540

    Open questions at the time
    • Genome-wide target repertoire in pituitary unknown
    • In vivo requirement not yet tested
  2. 1998 High

    Demonstration that PITX1 synergizes with SF-1 on the LHβ promoter and is required upstream of Lhx3 placed PITX1 at the apex of a pituitary transcriptional cascade, resolving its pan-pituitary regulatory role.

    Evidence Antisense knockdown in αT3-1 cells, co-transfection synergy assays across multiple promoters

    PMID:9514159

    Open questions at the time
    • Conditional pituitary-specific knockout phenotype not yet described
    • Chromatin-level mechanism of synergy with SF-1 unresolved
  3. 1999 High

    Loss-of-function in mice and gain-of-function in chick jointly established PITX1 as the hindlimb identity determinant acting through Tbx4, HoxC10, and HoxC11, answering the fundamental question of what specifies hindlimb versus forelimb.

    Evidence Pitx1 knockout mice (two independent labs), retroviral misexpression in chick wing bud, skeletal and molecular analysis

    PMID:10049363 PMID:10073939 PMID:10101115

    Open questions at the time
    • Direct versus indirect activation of Tbx4 not resolved at chromatin level
    • Enhancers controlling Pitx1 hindlimb-restricted expression not yet identified
  4. 1999 High

    Mapping the physical interaction between the PITX1 C-terminus and SF-1 N-terminus, and identifying Egr-1 as a GnRH-responsive factor that synergizes with PITX1 and SF-1, defined a tripartite transcriptional complex on the LHβ promoter linking extracellular signals to PITX1 function.

    Evidence Mammalian two-hybrid, domain-mapping mutagenesis, co-immunoprecipitation, PKC activation epistasis

    PMID:10082522 PMID:10369682

    Open questions at the time
    • Structural basis of PITX1-SF-1 interface unknown
    • Whether Egr-1 directly bridges PITX1 and SF-1 or acts independently on DNA not resolved
  5. 2000 High

    Discovery that PITX1 represses IFN-A promoters via the DNRE, with the C-terminal and homeodomain required, revealed a transcriptional repressor function distinct from its activator role, broadening its regulatory repertoire to innate immunity.

    Evidence Yeast one-hybrid identification, EMSA, reporter assays, antisense knockdown in virus-stimulated cells

    PMID:11003649

    Open questions at the time
    • Physiological relevance of IFN-A repression in antiviral immunity not tested in vivo
  6. 2002 High

    Identification of direct physical interaction between PITX1 homeodomain and IRF3/IRF7 clarified the mechanism of IFN-A repression as protein–protein sequestration rather than HDAC recruitment, distinguishing it mechanistically from other homeodomain repressors.

    Evidence Co-immunoprecipitation, domain-mapping mutagenesis, reporter assays, HDAC inhibitor experiments

    PMID:12242290

    Open questions at the time
    • Genome-wide impact on interferon gene network not assessed
    • In vivo role in viral infection not demonstrated
  7. 2005 High

    An RNAi screen identified PITX1 as a suppressor of RAS signaling through transcriptional activation of RASAL1, establishing PITX1 as a tumor suppressor linking a developmental transcription factor to oncogenic pathway control.

    Evidence RNAi library screen, RAS-dependence epistasis test, soft-agar transformation, RASAL1 expression rescue in colon cancer cells

    PMID:15960973

    Open questions at the time
    • Whether PITX1 loss activates RAS in non-colon cancer contexts not systematically tested
    • Direct ChIP on RASAL1 promoter not shown in this study
  8. 2007 High

    PITX1 was shown to directly bind and activate the p53 promoter, inducing p53-dependent cell-cycle arrest and apoptosis, revealing a second major tumor-suppressive output and explaining its growth-inhibitory effects in cancer cells.

    Evidence ChIP on p53 promoter, site-directed mutagenesis, siRNA knockdown, apoptosis assays in MCF-7 cells

    PMID:17762884

    Open questions at the time
    • Whether PITX1-driven p53 activation is relevant in developmental contexts unclear
    • Relative contribution of RASAL1 vs. p53 to tumor suppression not dissected
  9. 2007 High

    DUX4 was identified as a direct transcriptional activator of PITX1, binding a TAAT-core element in the PITX1 promoter, establishing an upstream regulatory input relevant to FSHD pathology.

    Evidence EMSA, site-directed mutagenesis, luciferase reporter, endogenous PITX1 induction by qRT-PCR in C2C12 cells

    PMID:17984056

    Open questions at the time
    • Whether DUX4-PITX1 axis operates in patient muscle in vivo not directly tested
  10. 2008 High

    A dominant-negative PITX1 homeodomain mutation (E130K) segregating with autosomal dominant clubfoot in a human family provided the first direct genetic link between PITX1 and human Mendelian limb malformation.

    Evidence Linkage analysis, luciferase reporter assays, dose-dependent suppression of wild-type PITX1 activity

    PMID:18950742

    Open questions at the time
    • Structural basis of E130K dominant-negative effect not resolved
    • Additional PITX1 mutations in clubfoot cohorts not yet surveyed
  11. 2009 High

    Repeated pelvic loss in sticklebacks was mapped to regulatory deletions of the PelA pelvic enhancer of Pitx1, providing the first example of a tissue-specific enhancer deletion driving morphological evolution at a developmental transcription factor locus.

    Evidence Population genetics, enhancer deletion analysis, expression studies in sticklebacks

    PMID:20007865

    Open questions at the time
    • Mammalian PelA ortholog function not tested
    • Whether PelA interacts with other enhancers in the Pitx1 locus unknown
  12. 2011 High

    Multiple studies converged to show that PITX1 directly suppresses hTERT transcription by binding conserved sites in the hTERT promoter, that Pitx1 haploinsufficiency causes clubfoot in mice paralleling the human phenotype, and that PITX1 selectively inhibits ERα/ERβ transcriptional activity while being estrogen-inducible, broadening the gene's functional scope to telomerase regulation, quantitative limb development, and hormone receptor modulation.

    Evidence ChIP and EMSA on hTERT promoter; Pitx1+/− mouse breeding with MRI and skeletal phenotyping; ChIP-Seq on ERα binding sites with siRNA in breast cancer cells

    PMID:21300782 PMID:21775501 PMID:21868451

    Open questions at the time
    • Whether hTERT suppression and ERα modulation are connected remains untested
    • Mechanism by which PITX1 inhibits ERα but enhances PR/GR activity not resolved
  13. 2012 High

    Genome-wide ChIP-Seq in mouse hindlimbs directly confirmed Tbx4, HoxC10, and HoxC11 as direct PITX1 targets and revealed preferential binding to hindlimb-specific enhancers, resolving the long-standing question of direct versus indirect Tbx4 regulation.

    Evidence ChIP-Seq with H3K27ac chromatin marking in E12.5 mouse hindlimbs

    PMID:23201014

    Open questions at the time
    • Time-resolved binding dynamics during limb specification not captured
    • Co-factor recruitment at hindlimb enhancers not identified
  14. 2013 High

    Discovery that RHAU helicase suppresses PITX1 protein expression post-transcriptionally through the miRNA/Ago2 pathway, without affecting mRNA levels, established a non-coding RNA-based regulatory layer controlling PITX1 abundance.

    Evidence RNA co-immunoprecipitation, siRNA knockdown of RHAU/Dicer/Ago2, Western blotting

    PMID:24369427

    Open questions at the time
    • Specific miRNA(s) recruited by RHAU to PITX1 mRNA not identified
    • Physiological context in which RHAU-mediated suppression operates not defined
  15. 2016 High

    PTP1B was identified as a direct phosphatase that dephosphorylates PITX1 at Y160/Y175/Y179, destabilizing the protein and reducing its transcriptional activity on RasGAP targets, linking tyrosine phosphorylation to PITX1 protein turnover and tumor suppressor output.

    Evidence FLAG pull-down, phosphorylation site mapping, PTP1B inhibition/silencing, reporter assays, xenograft validation

    PMID:26840794

    Open questions at the time
    • Kinase that phosphorylates PITX1 at these tyrosines not identified
    • Proteasomal versus other degradation pathway not determined
  16. 2017 High

    Integrated ChIP-Seq and RNA-Seq in Pitx1−/− hindlimbs identified ~440 direct targets including Sox9 and Six1, and showed PITX1 acts on similar chromatin states in both limbs, establishing that PITX1 redirects a generic limb program through a narrow set of hindlimb-restricted regulatory targets.

    Evidence ChIP-Seq, RNA-Seq in Pitx1−/− embryos, cross-species (mouse/Anolis) conservation analysis, H3K27ac chromatin profiling

    PMID:28807899 PMID:29273440

    Open questions at the time
    • Single-cell resolution of target activation dynamics not achieved in these studies
    • Pioneer factor versus cooperative binding mechanism not distinguished
  17. 2018 High

    Identification and CRISPR-deletion of a second pelvic enhancer (PelB) downstream of Pitx1, and demonstration that H2AFY promoter deletion causes Liebenberg syndrome by unshielding the Pen enhancer from Pitx1 in forelimbs, revealed a multi-enhancer regulatory landscape with insulator-dependent limb-type specificity.

    Evidence Transgenic enhancer reporters, CRISPR deletion in mice, stickleback population genetics, whole-genome sequencing of Liebenberg syndrome patients

    PMID:30499775 PMID:30711920

    Open questions at the time
    • Full 3D topology of enhancer–insulator interactions at Pitx1 locus not mapped at high resolution
    • Additional enhancers contributing to hindlimb expression may exist
  18. 2019 High

    PITX1 was shown to cooperate with SOX2 and TRP63 in a feed-forward circuit maintaining squamous cell carcinoma stem cell self-renewal, with KLF4 acting as a reciprocal repressor, revealing an oncogenic role for PITX1 in specific cancer contexts distinct from its tumor-suppressive functions.

    Evidence CRISPR knockout, ChIP-Seq, RNA-Seq, functional self-renewal assays in mouse and human SCC

    PMID:30713093

    Open questions at the time
    • Whether the PITX1 tumor-suppressor and SCC self-renewal functions depend on different target gene subsets not resolved
    • Context determinants that switch PITX1 from suppressor to oncogenic factor unknown
  19. 2021 High

    Single-cell transcriptomics of Pen enhancer-deleted embryos showed that Pitx1 regulatory landscape disruption causes heterochronic loss of high-expressing cells and clubfoot through failure to coordinate multiple enhancer activities, linking 3D chromatin architecture to quantitative Pitx1 dosage control.

    Evidence Pen enhancer CRISPR deletion, single-cell RNA-Seq, in-embryo cell tracing, 3D chromatin analysis

    PMID:34903763

    Open questions at the time
    • Whether PelA, PelB, and Pen act additively or synergistically on Pitx1 dosage not quantified
    • Upstream factors that coordinate enhancer activity remain unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include: the kinase(s) that phosphorylate PITX1 at tyrosine residues counteracting PTP1B; the structural basis for context-dependent switching between activator and repressor functions; whether PITX1 acts as a pioneer factor or cooperative binder at developmental enhancers; and how its tumor-suppressive versus pro-self-renewal activities are determined by cellular context.
  • Tyrosine kinase phosphorylating PITX1 unidentified
  • No crystal structure of PITX1 homeodomain–DNA complex available
  • Pioneer versus cooperative binding mechanism at limb enhancers not distinguished
  • Molecular basis for context-dependent oncogenic vs. tumor-suppressive roles unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 9 GO:0003677 DNA binding 7
Localization
GO:0005634 nucleus 2
Pathway
R-HSA-1266738 Developmental Biology 8 R-HSA-162582 Signal Transduction 2 R-HSA-168256 Immune System 2 R-HSA-5357801 Programmed Cell Death 2
Partners
EGR1HIF1BIRF3IRF7PIT1SF1SOX2ZCCHC10

Evidence

Reading pass · 43 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1996 PITX1 (Ptx1) is a bicoid-related homeodomain transcription factor that activates transcription of the POMC gene by binding sequences related to Drosophila bicoid target sites in a pituitary-cell-specific manner. Transcription factor cloning from AtT-20 cells, DNA-binding assays, reporter gene assays, in situ hybridization Genes & development High 8675014
1996 PITX1 (P-OTX) physically interacts with the transactivation domain of the pituitary-specific POU domain protein Pit-1, and synergizes with Pit-1 to activate pituitary-specific target gene promoters. Interaction-based cloning, co-activation reporter assays in pituitary cell lines Proceedings of the National Academy of Sciences of the United States of America High 8755540
1998 PITX1 acts as a pan-pituitary transcriptional activator that synergizes with SF-1 on the LHβ promoter and with Pit1 on the PRL promoter; antisense depletion shows the downstream Lim3/Lhx3 gene is highly dependent on PITX1, placing PITX1 upstream of Lhx3 in a pituitary transcriptional cascade. Reporter gene assays, antisense RNA knockdown in αT3-1 cells, co-transfection synergy assays Molecular endocrinology (Baltimore, Md.) High 9514159
1999 Pitx1 gene deletion in mice causes severe hindlimb morphogenesis defects (absent ilium, underdeveloped long bones, loss of knee cartilage) with decreased Tbx4 expression in the hindlimb, demonstrating Pitx1 is required upstream of Tbx4 for hindlimb identity and chondrogenesis. Targeted gene knockout in mice, in situ hybridization, skeletal analysis Development (Cambridge, England) High 10101115
1999 Pitx1 gene deletion causes striking hindlimb abnormalities (tibia/fibula and patella defects resembling forelimb) with decreased distal Tbx4 expression; misexpression of Pitx1 in chick wing bud induces Tbx4 and causes hindlimb-like digit morphology, establishing Pitx1 as a hindlimb identity determinant acting through Tbx4. Mouse knockout, chick limb misexpression (retroviral), skeletal morphology analysis, in situ hybridization Genes & development High 10049363
1999 Misexpression of Pitx1 in the chick wing bud induces distal expression of Tbx4, HoxC10, and HoxC11, and transforms wing morphology toward hindlimb characteristics, placing Pitx1 upstream of Tbx4 in the hindlimb identity pathway. Retroviral misexpression in chick wing bud, in situ hybridization, morphological analysis Science (New York, N.Y.) High 10073939
1999 PITX1 C-terminus directly interacts with the N-terminal half of SF-1; this physical interaction enhances SF-1 transcriptional activity on LHβ and MIS promoters to a level equivalent to a constitutively active SF-1 mutant, mimicking the effect of an SF-1 ligand. Mammalian two-hybrid assay, reporter gene assays, domain-mapping mutagenesis, co-transfection The EMBO journal High 10369682
1999 GnRH induces Egr-1 expression (but not Pitx1 or SF-1); Egr-1 then directly interacts with Pitx1 and SF-1, enhancing Pitx1- and SF-1-induced LHβ transcription, establishing Egr-1 as a GnRH-responsive transcriptional mediator that functions through physical interaction with PITX1. Reporter gene assays, PKC activation, direct protein interaction assays (co-immunoprecipitation/pull-down implied), synergy assays Molecular and cellular biology High 10082522
1999 PITX1 is expressed in all pituitary cell types but at differentially quantitative levels; highest expression correlates with α-glycoprotein subunit-expressing cells throughout pituitary development, as shown by co-immunolocalization. Immunohistochemistry, co-immunolocalization, differential mRNA/protein quantification Endocrinology Medium 10067870
2000 FGF8 can induce/maintain Pitx1 and Pitx2 expression in the developing mandible, while BMP4 represses Pitx1 expression in mandibular mesenchyme, as shown by bead implantation experiments establishing antagonistic FGF8/BMP4 regulation of Pitx1. Bead implantation experiments in mouse embryos, in situ hybridization Developmental biology High 10625557
2000 Pitx1 represses virus-induced IFN-A promoters by binding to the distal negative regulatory element (DNRE); the C-terminal region and homeodomain of Pitx1 are required for repression; antisense Pitx1 increases endogenous IFN-A transcription. Yeast one-hybrid (DNRE-binding protein identification), reporter assays, antisense RNA, EMSA, domain-mapping mutagenesis Molecular and cellular biology High 11003649
2001 A single Pitx1 binding site in the LHβ promoter is absolutely required for promoter activity in transgenic mice; mutation of this element abolishes both basal activity and GnRH responsiveness, demonstrating that cooperative interactions between Pitx1, SF-1, and Egr-1 depend on Pitx1 DNA binding in vivo. Transgenic mouse reporter assays, transient transfection in LβT2 gonadotrope-derived cells, site-directed mutagenesis Molecular endocrinology (Baltimore, Md.) High 11328855
2002 PITX1 physically interacts with IRF3 and IRF7 via its homeodomain; specific C-terminal domains of Pitx1 mediate trans-repression of IFN-A11 and IFN-A5 (but not IFN-A4) promoter activities, and this repression is not mediated by histone deacetylase recruitment. Co-immunoprecipitation, domain-mapping mutagenesis, reporter gene assays, EMSA Molecular and cellular biology High 12242290
2002 Pitx1 can homodimerize, phosphorylates on three residues when DNA-bound, and acts through multiple mechanisms on the LHβ promoter including synergy with SF-1 and estrogen receptor, binding to four upstream Pitx1 response elements, and inducing conformational changes in the DNA as shown by circular permutation assay. Mammalian two-hybrid (homodimerization), circular permutation assay (DNA bending), phosphorylation analysis, reporter gene assays The Journal of biological chemistry Medium 12011080
2003 PITX1 positively autoregulates its own promoter in a DNA-binding- and transactivation-domain-dependent manner; Pitx1, Pitx1b, Pitx2, and Otx1 all activate the PITX1 promoter in transfection assays, while transgenic mouse studies show that PITX1 promoter fragments reproduce anterior (but not posterior) expression. Transgenic mouse reporter assays, transient transfection, domain-mapping mutagenesis Neuroendocrinology Medium 14512705
2003 HCV NS5A protein physically interacts with human PITX1 (hPTX1) as identified by yeast two-hybrid and confirmed by mammalian two-hybrid, co-immunoprecipitation, and colocalization; co-expression of NS5A and hPTX1 reduces IFN-α promoter activity compared to either alone. Yeast two-hybrid, mammalian two-hybrid, co-immunoprecipitation, colocalization, reporter assays Virology Medium 12620797
2005 PITX1 suppresses RAS pathway activity and tumorigenicity by transcriptionally activating RASAL1, a RAS-GTPase-activating protein; knockdown of PITX1 activates RAS signaling and transforms human primary cells, while restoration of PITX1 in colon cancer cells inhibits tumorigenicity in a wild-type RAS-dependent manner. RNAi library screen, reporter assays, soft-agar transformation assay, expression analysis, epistasis (RAS-dependence test) Cell High 15960973
2007 DUX4 protein directly binds a 30-bp sequence in the PITX1 promoter (TAAT core required) and transcriptionally activates both a PITX1 luciferase reporter and the endogenous PITX1 gene in C2C12 cells. Luciferase reporter assays, EMSA, site-directed mutagenesis of TAAT core, qRT-PCR of endogenous PITX1 Proceedings of the National Academy of Sciences of the United States of America High 17984056
2007 PITX1 directly activates transcription of the p53 gene by binding to two PITX1 consensus elements in the p53 promoter, including one within the first exon; forced PITX1 expression causes p53-dependent cell-cycle arrest and apoptosis in MCF-7 cells, and PITX1 siRNA reduces basal p53 expression. Luciferase reporter assays, ChIP, site-directed mutagenesis, siRNA knockdown, apoptosis assays, dominant-negative PITX1 Cell death and differentiation High 17762884
2007 Bone morphogenetic protein-4 (BMP4) down-regulates Pitx1 expression in both mandibular mesenchyme and dental epithelium, as shown by tissue recombination and bead implantation experiments; Pitx1 deletion results in decreased Barx1 expression in molar mesenchyme and suppression of Tbx1 in dental epithelium. Tissue recombination, bead implantation, in situ hybridization, Pitx1-/- mouse analysis Developmental biology High 18082678
2008 A missense mutation in the PITX1 homeodomain (E130K) reduces PITX1 transactivation activity in luciferase reporter assays and suppresses wild-type PITX1 activity in a dose-dependent manner, indicating dominant-negative effects; this mutation segregates with autosomal dominant lower-limb malformations including clubfoot. Luciferase reporter assay, dominant-negative suppression assay, linkage analysis American journal of human genetics High 18950742
2009 Pelvic loss in threespine sticklebacks evolves repeatedly through regulatory mutations deleting a tissue-specific pelvic enhancer of Pitx1 (PelA), reducing Pitx1 expression selectively in pelvic tissue without affecting the rest of Pitx1 expression; this represents an enhancer-based mechanism for morphological evolution. Population genetics, enhancer deletion analysis, expression studies, sequence analysis for selection signatures Science (New York, N.Y.) High 20007865
2011 PITX1 suppresses hTERT transcription by directly binding to conserved binding sites in the hTERT promoter (three sites in hTERT, one in mouse Tert), as shown by in vitro and in vivo (ChIP) binding assays, ultimately reducing telomerase activity. Microcell-mediated chromosome transfer, cDNA microarray, luciferase reporter assays, EMSA (in vitro binding), ChIP (in vivo binding) Molecular and cellular biology High 21300782
2011 Pitx1 haploinsufficiency causes clubfoot in mice with 8.9% penetrance; the affected hindlimb shows peroneal artery hypoplasia and reduced lateral muscle compartments; skeletal muscle gene expression is significantly reduced in Pitx1-/- E12.5 hindlimb buds, indicating early muscle developmental defects. Pitx1 heterozygous mouse breeding, copy number analysis in human patients, MRI, skeletal phenotyping, gene expression analysis Human molecular genetics High 21775501
2011 PITX1 expression is robustly induced by estradiol (E2) in ERα-positive breast cancer cells via ERα-dependent interaction between the PITX1 proximal promoter and an upstream enhancer; PITX1 selectively inhibits ERα and ERβ transcriptional activity while enhancing glucocorticoid and progesterone receptor activities, and PITX1 is co-recruited with ERα to ERα binding sites. ChIP, reporter assays, siRNA knockdown, genome-wide ERα binding site analysis Molecular endocrinology (Baltimore, Md.) High 21868451
2011 Pitx1 is necessary for normal hindlimb outgrowth by regulating Tbx4 expression levels; a transgenic gene replacement strategy uncouples two discrete functions: (1) influencing hindlimb outgrowth through Tbx4 regulation, and (2) shaping hindlimb bone/soft tissue morphology independently of Tbx4, via localized modulation of growth rate of skeletal elements. Transgenic Pitx1 rescue in Pitx1-/- background, skeletal morphometry, molecular expression analysis Development (Cambridge, England) High 22071103
2012 Genome-wide ChIP-Seq in mouse hindlimbs shows Pitx1 binding is significantly enriched near limb morphogenesis genes including Tbx4, HoxC10, and HoxC11; Pitx1 is directly bound to the HLEA and HLEB hindlimb enhancers of Tbx4 and a Tbx2 hindlimb enhancer; Pitx1 binding is significantly enriched on hindlimb-specific vs. forelimb-specific cis-regulatory elements. ChIP-Seq, H3K27ac chromatin marking, genome-wide analysis of limb enhancers Developmental biology High 23201014
2012 Conditional muscle-specific overexpression of PITX1 in mice causes skeletal muscle dystrophy (weight loss, muscle mass reduction, atrophic fibers, necrosis, inflammation) with upregulation of p53 in affected muscles, suggesting PITX1 drives atrophy through p53-dependent pathways. Tet-repressible transgenic mouse model, histopathology, immunoblotting, immunohistochemistry, grip strength testing Biology open High 23125914
2013 The RNA helicase RHAU (DHX36) binds the PITX1 mRNA via a non-quadruplex-forming region and suppresses PITX1 protein expression post-transcriptionally through microRNA machinery (requiring Dicer and Argonaute-2) without substantially affecting mRNA levels. RNA co-immunoprecipitation, siRNA knockdown of RHAU/Dicer/Ago2, Western blotting, RNA G-quadruplex characterization Nucleic acids research High 24369427
2014 PITX1 associates with HIF-1β and is required for HIF-1α-dependent induction of specific histone demethylases (JMJD2B, JMJD2A, JMJD2C, JMJD1B) but not all HIF-1 target genes; PITX1-depleted cells show increased apoptosis and reduced proliferation under hypoxia. Co-immunoprecipitation (PITX1-HIF-1β interaction), siRNA knockdown, gene expression analysis, apoptosis/proliferation assays Cell cycle (Georgetown, Tex.) Medium 25558831
2015 miR-19b directly inhibits PITX1 mRNA translation through a binding site in the 3'UTR of PITX1 mRNA, leading to increased hTERT expression; overexpression of miR-19b reduces PITX1 protein without substantially affecting mRNA, establishing miR-19b as an upstream regulator of the PITX1-hTERT suppressor axis. miR-19b overexpression, 3'UTR luciferase reporter assays, Western blotting, qRT-PCR Scientific reports Medium 25643913
2016 PTP1B directly dephosphorylates PITX1 at Y160, Y175, and Y179, destabilizing PITX1 protein; PTP1B-dependent reduction in PITX1 decreases its transcriptional activity on the p120RasGAP (RASA1) promoter; PTP1B inhibition or sorafenib treatment hyperphosphorylates PITX1 and upregulates the PITX1-p120RasGAP axis. FLAG pull-down, phosphorylation site mapping, PTP1B inhibition, PTP1B silencing, reporter assays, molecular docking, in vivo xenograft Hepatology (Baltimore, Md.) High 26840794
2016 E2F1, in complex with its dimerization partner TFDP1, directly activates PITX1 transcription by binding to two specific sequences in the PITX1 proximal promoter, as confirmed by ChIP and DNA pulldown; TFDP1 knockdown reduces both PITX1 promoter activity and mRNA levels in articular chondrocytes. Luciferase reporter assays, ChIP, DNA pulldown, siRNA knockdown (TFDP1) PloS one High 27802335
2017 ChIP-Seq and RNA-Seq in Pitx1-/- mouse hindlimbs identify 440 candidate direct PITX1 targets; 68 are ultra-conserved between mouse and Anolis lizard hindlimbs, including Sox9 and Six1, indicating PITX1 directly promotes chondrogenesis and myogenesis by activating key members of cartilage and muscle transcriptional networks. ChIP-Seq, RNA-Seq in Pitx1-/- embryos, cross-species (mouse/Anolis) comparison Developmental biology High 29273440
2017 Expression profiling and direct Pitx1 target analysis show Pitx1 acts on sites in a similar chromatin state in both forelimb and hindlimb, controlling both patterning genes and the chondrogenic program, consistent with impaired chondrogenesis in Pitx1-/- hindlimbs; Pitx1 operates within a narrow network of hindlimb-restricted regulators to redirect the generic limb program. RNA-Seq, ChIP-Seq, H3K27ac chromatin profiling in FL/HL, Pitx1-/- analysis Development (Cambridge, England) High 28807899
2018 A newly identified pelvic enhancer (PelB) downstream of Pitx1 drives expression in the posterior hindlimb; PelB deletion in mice reduces hindlimb structure size; a wild stickleback population lacking the pelvis has an insertion/deletion disrupting PelB, showing this ancient enhancer contributes to evolutionary pelvic appendage modification. Transgenic enhancer reporter assay, CRISPR deletion in mice, skeletal phenotyping, stickleback population genetics eLife High 30499775
2019 PITX1 cooperates with SOX2 and TRP63 in squamous cell carcinoma tumor propagating cells to sustain a transcriptional feed-forward circuit that maintains self-renewal while repressing KLF4-dependent differentiation; PITX1 knockdown inhibits self-renewal and KLF4 overexpression represses PITX1/SOX2/TRP63 expression, forming a bistable network. Gene targeting (CRISPR), ChIP-Seq, RNA-Seq, functional self-renewal assays in mouse and human SCC Cell stem cell High 30713093
2019 PITX1 interacts with ZCCHC10 via its homeodomain; co-expression of PITX1 and ZCCHC10 cooperatively suppresses hTERT transcription in melanoma cells; homeodomain-deleted PITX1 cannot interact with ZCCHC10 and does not suppress hTERT, identifying PITX1-ZCCHC10 as a functional transcriptional repressor complex. FLAG pull-down assay, co-expression functional assays, deletion mutagenesis of homeodomain, qRT-PCR PloS one Medium 31404068
2019 H2AFY promoter deletion causes ectopic Pitx1 expression in forelimbs (Liebenberg syndrome) because the H2AFY promoter insulates the Pen hindlimb enhancer from Pitx1 in forelimbs; loss of this insulation allows the pan-limb active Pen enhancer to drive Pitx1 in forelimbs, demonstrated by CRISPR-Cas9 re-engineering of the human deletion in mouse. Whole genome sequencing (human patients), CRISPR-Cas9 engineering in mouse, expression analysis Journal of medical genetics High 30711920
2020 PITX1 drives astrocyte differentiation from human embryonic stem cells by directly activating the SOX9 promoter through a unique binding motif; PITX1 overexpression accelerates astrocyte differentiation and increases SOX9 expression, while PITX1 knockdown blocks differentiation and reduces SOX9. Luciferase reporter assays, EMSA, ChIP, siRNA knockdown, overexpression, human ESC differentiation assays The Journal of biological chemistry High 32759168
2021 Deletion of the Pen enhancer disrupts the Pitx1 regulatory landscape: single-cell transcriptomics and in-embryo cell tracing show increased fraction of Pitx1 non/low-expressing cells and loss of Pitx1 high-expressing cells, due to failure to coordinate enhancer activities and 3D chromatin changes, leading to a localized heterochrony, loss of irregular connective tissue, and a clubfoot phenotype. Pen enhancer deletion, single-cell RNA-Seq, in-embryo cell tracing, 3D chromatin analysis Nature communications High 34903763
2022 PITX1 interacts with STAT3 transcription factor, leading to decreased STAT3 transcriptional activity, which represses LINC00662 expression; PITX1 knockdown increases LINC00662, which is packaged into exosomes and activates M2 macrophage polarization, promoting osteosarcoma metastasis via CCL22. Ubiquitination assays, rescue experiments, co-immunoprecipitation implied, cell co-culture, exosome isolation assays Clinical & experimental metastasis Medium 36334221
2010 SEDLIN interacts with PITX1 in the nucleus; SEDT-associated SEDLIN mutations (Ser73Leu, Phe83Ser, Val130Asp, Gln131Stop, but not Asp47Tyr) abolish interaction with PITX1 in yeast assays (where homodimerization masking is absent); wild-type SEDLIN localizes to both cytoplasm and nucleus. Yeast two-hybrid, COS7 cell co-expression, subcellular localization, 3D structural modeling PloS one Medium 20498720

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2009 Adaptive evolution of pelvic reduction in sticklebacks by recurrent deletion of a Pitx1 enhancer. Science (New York, N.Y.) 739 20007865
1999 Role of the Bicoid-related homeodomain factor Pitx1 in specifying hindlimb morphogenesis and pituitary development. Genes & development 340 10049363
1996 Ptx1, a bicoid-related homeo box transcription factor involved in transcription of the pro-opiomelanocortin gene. Genes & development 337 8675014
2007 DUX4, a candidate gene of facioscapulohumeral muscular dystrophy, encodes a transcriptional activator of PITX1. Proceedings of the National Academy of Sciences of the United States of America 297 17984056
1998 The pan-pituitary activator of transcription, Ptx1 (pituitary homeobox 1), acts in synergy with SF-1 and Pit1 and is an upstream regulator of the Lim-homeodomain gene Lim3/Lhx3. Molecular endocrinology (Baltimore, Md.) 240 9514159
2005 A genetic screen identifies PITX1 as a suppressor of RAS activity and tumorigenicity. Cell 237 15960973
1999 Hindlimb patterning and mandible development require the Ptx1 gene. Development (Cambridge, England) 234 10101115
1999 Role of Pitx1 upstream of Tbx4 in specification of hindlimb identity. Science (New York, N.Y.) 232 10073939
1999 Egr-1 is a downstream effector of GnRH and synergizes by direct interaction with Ptx1 and SF-1 to enhance luteinizing hormone beta gene transcription. Molecular and cellular biology 225 10082522
1996 P-OTX: a PIT-1-interacting homeodomain factor expressed during anterior pituitary gland development. Proceedings of the National Academy of Sciences of the United States of America 221 8755540
1997 The bicoid-related homeoprotein Ptx1 defines the most anterior domain of the embryo and differentiates posterior from anterior lateral mesoderm. Development (Cambridge, England) 186 9226452
2000 Antagonistic signals between BMP4 and FGF8 define the expression of Pitx1 and Pitx2 in mouse tooth-forming anlage. Developmental biology 168 10625557
2010 BROTHER OF FT AND TFL1 (BFT) has TFL1-like activity and functions redundantly with TFL1 in inflorescence meristem development in Arabidopsis. The Plant journal : for cell and molecular biology 108 20409005
1999 Ptx1 regulates SF-1 activity by an interaction that mimics the role of the ligand-binding domain. The EMBO journal 107 10369682
2008 Asymmetric lower-limb malformations in individuals with homeobox PITX1 gene mutation. American journal of human genetics 105 18950742
1999 Pituitary homeobox 1 (Ptx1) is differentially expressed during pituitary development. Endocrinology 88 10067870
2008 Analysis and distribution of class 1 and class 2 integrons and associated gene cassettes among Escherichia coli isolates from swine, horses, cats and dogs collected in the BfT-GermVet monitoring study. The Journal of antimicrobial chemotherapy 79 18550679
2013 The Arabidopsis floral repressor BFT delays flowering by competing with FT for FD binding under high salinity. Molecular plant 77 23935007
2001 A single Pitx1 binding site is essential for activity of the LHbeta promoter in transgenic mice. Molecular endocrinology (Baltimore, Md.) 75 11328855
2000 Transcriptional properties of Ptx1 and Ptx2 isoforms. Neuroendocrinology 75 10859489
2013 The RNA helicase RHAU (DHX36) suppresses expression of the transcription factor PITX1. Nucleic acids research 69 24369427
2007 Transcriptional activation of p53 by Pitx1. Cell death and differentiation 65 17762884
2011 Pitx1 haploinsufficiency causes clubfoot in humans and a clubfoot-like phenotype in mice. Human molecular genetics 64 21775501
2011 Identification of PITX1 as a TERT suppressor gene located on human chromosome 5. Molecular and cellular biology 63 21300782
2007 Methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius detected in the BfT-GermVet monitoring programme 2004-2006 in Germany. The Journal of antimicrobial chemotherapy 63 18096559
2012 Loss of desmocollin 1-3 and homeobox genes PITX1 and CDX2 are associated with tumor progression and survival in colorectal carcinoma. International journal of colorectal disease 62 22438068
2015 miR-19b regulates hTERT mRNA expression through targeting PITX1 mRNA in melanoma cells. Scientific reports 59 25643913
2000 Identification of two genetic groups in Bacteroides fragilis by multilocus enzyme electrophoresis: distribution of antibiotic resistance (cfiA, cepA) and enterotoxin (bft) encoding genes. Microbiology (Reading, England) 57 10832652
2007 Molecular basis of resistance to macrolides and lincosamides among staphylococci and streptococci from various animal sources collected in the resistance monitoring program BfT-GermVet. International journal of antimicrobial agents 56 17307339
2011 Pitx1 is necessary for normal initiation of hindlimb outgrowth through regulation of Tbx4 expression and shapes hindlimb morphologies via targeted growth control. Development (Cambridge, England) 50 22071103
2012 Pitx1 broadly associates with limb enhancers and is enriched on hindlimb cis-regulatory elements. Developmental biology 49 23201014
2007 Deletion of the Pitx1 genomic locus affects mandibular tooth morphogenesis and expression of the Barx1 and Tbx1 genes. Developmental biology 49 18082678
1997 Embryonic expression and characterization of a Ptx1 homolog in Drosophila. Mechanisms of development 49 9431811
2000 A new subtype of the metalloprotease toxin gene and the incidence of the three bft subtypes among Bacteroides fragilis isolates in Japan. FEMS microbiology letters 48 10612750
2024 Microbiota enterotoxigenic Bacteroides fragilis-secreted BFT-1 promotes breast cancer cell stemness and chemoresistance through its functional receptor NOD1. Protein & cell 47 38437016
1993 ptx1, a nonphototactic mutant of Chlamydomonas, lacks control of flagellar dominance. The Journal of cell biology 45 8425899
2011 Analysis of bla(CTX-M)-carrying plasmids from Escherichia coli isolates collected in the BfT-GermVet study. Applied and environmental microbiology 43 21685166
2012 Conditional over-expression of PITX1 causes skeletal muscle dystrophy in mice. Biology open 42 23125914
2011 The floral repressor BROTHER OF FT AND TFL1 (BFT) modulates flowering initiation under high salinity in Arabidopsis. Molecules and cells 42 21809215
2012 Deletions in PITX1 cause a spectrum of lower-limb malformations including mirror-image polydactyly. European journal of human genetics : EJHG 41 22258522
2019 Circular RNA circ-PITX1 promotes the progression of glioblastoma by acting as a competing endogenous RNA to regulate miR-379-5p/MAP3K2 axis. European journal of pharmacology 40 31493405
2019 De Novo PITX1 Expression Controls Bi-Stable Transcriptional Circuits to Govern Self-Renewal and Differentiation in Squamous Cell Carcinoma. Cell stem cell 37 30713093
2018 A novel enhancer near the Pitx1 gene influences development and evolution of pelvic appendages in vertebrates. eLife 37 30499775
2017 Three FT and multiple CEN and BFT genes regulate maturity, flowering, and vegetative phenology in kiwifruit. Journal of experimental botany 37 28369532
2016 Protein tyrosine phosphatase 1B dephosphorylates PITX1 and regulates p120RasGAP in hepatocellular carcinoma. Hepatology (Baltimore, Md.) 37 26840794
2002 Multiple mechanisms for Pitx-1 transactivation of a luteinizing hormone beta subunit gene. The Journal of biological chemistry 36 12011080
1999 Expression of Ptx1 in the adult rat pituitary glands and pituitary cell lines: hormone-secreting cells and folliculo-stellate cells. Cell and tissue research 33 10555539
2017 Pitx1 directly modulates the core limb development program to implement hindlimb identity. Development (Cambridge, England) 32 28807899
2000 The alleles of the bft gene are distributed differently among enterotoxigenic Bacteroides fragilis strains from human sources and can be present in double copies. Journal of clinical microbiology 31 10655354
2020 Effect of acute exposure to ammonia and BFT alterations on Rhynchocypris lagowski: Digestive enzyme, inflammation response, oxidative stress and immunological parameters. Environmental toxicology and pharmacology 30 32416163
2024 Entero-toxigenic Bacteroides fragilis contributes to intestinal barrier injury and colorectal cancer progression by mediating the BFT/STAT3/ZEB2 pathway. Cell cycle (Georgetown, Tex.) 28 38273425
2020 Mutations Upstream of the TBX5 and PITX1 Transcription Factor Genes Are Associated with Feathered Legs in the Domestic Chicken. Molecular biology and evolution 28 32344431
2011 The estrogen-regulated transcription factor PITX1 coordinates gene-specific regulation by estrogen receptor-alpha in breast cancer cells. Molecular endocrinology (Baltimore, Md.) 28 21868451
2001 Characterization of 5'-flanking region of rat somatostatin receptor sst2 gene: transcriptional regulatory elements and activation by Pitx1 and estrogen. Endocrinology 28 11250922
2007 Association of autism with polymorphisms in the paired-like homeodomain transcription factor 1 (PITX1) on chromosome 5q31: a candidate gene analysis. BMC medical genetics 27 18053270
2002 Modulation of bft expression by the Bacteroides fragilis pathogenicity island and its flanking region. Molecular microbiology 27 12180925
1997 Human and murine PTX1/Ptx1 gene maps to the region for Treacher Collins syndrome. Mammalian genome : official journal of the International Mammalian Genome Society 27 9337397
2011 Activation of Paired-homeobox gene PITX1 by del(5)(q31) in T-cell acute lymphoblastic leukemia. Leukemia & lymphoma 25 21425961
2005 The distribution of the bft alleles among enterotoxigenic Bacteroides fragilis strains from stool specimens and extraintestinal sites. Anaerobe 25 16701617
1997 Flagellar photoresponses of ptx1, a nonphototactic mutant of Chlamydomonas. Cell motility and the cytoskeleton 24 9186008
2019 MicroRNA-1204 promotes cell proliferation by regulating PITX1 in non-small-cell lung cancer. Cell biology international 23 30549141
2017 PITX1 promotes chondrogenesis and myogenesis in mouse hindlimbs through conserved regulatory targets. Developmental biology 23 29273440
2013 Liebenberg syndrome is caused by a deletion upstream to the PITX1 gene resulting in transformation of the upper limbs to reflect lower limb characteristics. Gene 23 23587911
2022 CRISPR-Cas9-mediated mutagenesis of kiwifruit BFT genes results in an evergrowing but not early flowering phenotype. Plant biotechnology journal 22 35796629
2019 MiR-675 is frequently overexpressed in gastric cancer and enhances cell proliferation and invasion via targeting a potent anti-tumor gene PITX1. Cellular signalling 22 31260797
2011 PITX2 AND PITX1 regulate thyrotroph function and response to hypothyroidism. Molecular endocrinology (Baltimore, Md.) 22 21964592
2022 Serum Proteins, HMMR, NXPH4, PITX1 and THBS4; A Panel of Biomarkers for Early Diagnosis of Hepatocellular Carcinoma. Journal of clinical medicine 21 35456219
2019 The presence of antibiotic resistance genes and bft genes as well as antibiotic susceptibility testing of Bacteroides fragilis strains isolated from inpatients of the Infant Jesus Teaching Hospital, Warsaw during 2007-2012. Anaerobe 21 30844502
2018 Abnormal PITX1 gene methylation in adolescent idiopathic scoliosis: a pilot study. BMC musculoskeletal disorders 21 29743058
2010 SEDLIN forms homodimers: characterisation of SEDLIN mutations and their interactions with transcription factors MBP1, PITX1 and SF1. PloS one 21 20498720
2023 CRISPR/Cas9 mutants delineate roles of Populus FT and TFL1/CEN/BFT family members in growth, dormancy release and flowering. Tree physiology 20 36892416
2019 H2AFY promoter deletion causes PITX1 endoactivation and Liebenberg syndrome. Journal of medical genetics 20 30711920
2019 PITX1 protein interacts with ZCCHC10 to regulate hTERT mRNA transcription. PloS one 20 31404068
2016 E2F1 and TFDP1 Regulate PITX1 Expression in Normal and Osteoarthritic Articular Chondrocytes. PloS one 20 27802335
2007 Determination of bft gene subtypes in Bacteroides fragilis clinical isolates. Journal of clinical microbiology 20 17301286
2015 Biophysical Characterization of G-Quadruplex Recognition in the PITX1 mRNA by the Specificity Domain of the Helicase RHAU. PloS one 19 26649896
2002 Repression by homeoprotein pitx1 of virus-induced interferon a promoters is mediated by physical interaction and trans repression of IRF3 and IRF7. Molecular and cellular biology 19 12242290
2001 Pitx1 and Pitx2c are required for ectopic cement gland formation in Xenopus laevis. Genesis (New York, N.Y. : 2000) 19 11477694
2021 Circ-PITX1 Promotes the Progression of Non-Small Cell Lung Cancer Through Regulating the miR-1248/CCND2 Axis. OncoTargets and therapy 18 33727831
2021 Cell-specific alterations in Pitx1 regulatory landscape activation caused by the loss of a single enhancer. Nature communications 18 34903763
2010 BROTHER OF FT AND TFL1 (BFT), a member of the FT/TFL1 family, shows distinct pattern of expression during the vegetative growth of Arabidopsis. Plant signaling & behavior 18 20930566
1997 Backfoot, a novel homeobox gene, maps to human chromosome 5 (BFT) and mouse chromosome 13 (Bft). Genomics 18 9070926
2022 The circ-PITX1 promotes non-small cell lung cancer development via the miR-30e-5p/ITGA6 axis. Cell cycle (Georgetown, Tex.) 17 35007184
2014 PITX1, a specificity determinant in the HIF-1α-mediated transcriptional response to hypoxia. Cell cycle (Georgetown, Tex.) 17 25558831
2000 Repression of virus-induced interferon A promoters by homeodomain transcription factor Ptx1. Molecular and cellular biology 17 11003649
2021 Immunity-longevity tradeoff neurally controlled by GABAergic transcription factor PITX1/UNC-30. Cell reports 16 34038721
2018 Disrupting the three-dimensional regulatory topology of the Pitx1 locus results in overtly normal development. Development (Cambridge, England) 16 29549111
2014 miR‑886‑3p upregulation in clear cell renal cell carcinoma regulates cell migration, proliferation and apoptosis by targeting PITX1. International journal of molecular medicine 16 25190136
2003 Modulation of interferon expression by hepatitis C virus NS5A protein and human homeodomain protein PTX1. Virology 16 12620797
2022 PITX1 suppresses osteosarcoma metastasis through exosomal LINC00662-mediated M2 macrophage polarization. Clinical & experimental metastasis 15 36334221
2020 The transcription factor PITX1 drives astrocyte differentiation by regulating the SOX9 gene. The Journal of biological chemistry 15 32759168
2013 Morpholino treatment improves muscle function and pathology of Pitx1 transgenic mice. Molecular therapy : the journal of the American Society of Gene Therapy 15 24232919
2007 New emerging role of pitx1 transcription factor in osteoarthritis pathogenesis. Clinical orthopaedics and related research 15 17549029
2023 PITX1 plays essential functions in cancer. Frontiers in oncology 14 37841446
2019 Overexpression of Pitx1 attenuates the senescence of chondrocytes from osteoarthritis degeneration cartilage-A self-controlled model for studying the etiology and treatment of osteoarthritis. Bone 14 31783149
2015 Strong expression of paired-like homeodomain transcription factor 1 (PITX1) is associated with a favorable outcome in human osteosarcoma. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 14 25936343
2003 Pitx1 in vivo promoter activity and mechanisms of positive autoregulation. Neuroendocrinology 14 14512705
2000 Expression of the pituitary transcription factor Ptx-1, but not that of the trans-activating factor prop-1, is reduced in human corticotroph adenomas and is associated with decreased alpha-subunit secretion. The Journal of clinical endocrinology and metabolism 14 10902805
2024 Biofloc Technology (BFT) in Aquaculture: What Goes Right, What Goes Wrong? A Scientific-Based Snapshot. Aquaculture nutrition 13 38239306
2016 PITX1 is a novel predictor of the response to chemotherapy in head and neck squamous cell carcinoma. Molecular and clinical oncology 13 27330773