{"gene":"SP2","run_date":"2026-06-10T07:46:38","timeline":{"discoveries":[{"year":2015,"finding":"Sp2 binds to CCAAT motifs genome-wide in mouse embryonic fibroblasts via its glutamine-rich amino-terminal region, independently of its zinc finger domain, and recruits the histone-fold CCAAT-binding factor Nf-y; Nf-y is critical for recruitment of Sp2 to co-occupied regulatory elements, and reciprocally Sp2 potentiates Nf-y binding at shared sites.","method":"ChIP-seq in MEFs; re-expression of Sp2/Sp3 zinc finger mutants in corresponding knockout MEFs; co-occupancy analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq with mutant rescue in matched KO MEFs, multiple orthogonal methods (ChIP-seq, mutant re-expression, motif analysis), single lab but rigorous design","pmids":["25793500"],"is_preprint":false},{"year":2018,"finding":"Sp2 is recruited to composite genomic sites containing a TALE homeoprotein recognition sequence and an Nf-y recognition sequence separated by ~11 bp; a complex of Pbx1:Prep1 and Nf-y recruits Sp2 to co-occupied regulatory elements, and in turn Sp2 potentiates binding of Pbx1:Prep1 and Nf-y. The Sp-box motif near the Sp2 N-terminus is required for this cofactor function.","method":"ChIP-exo sequencing in MEFs; co-immunoprecipitation; domain deletion/mutation analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP-exo with mutational follow-up, reciprocal Co-IP, composite motif identification, single lab with multiple orthogonal methods","pmids":["30337366"],"is_preprint":false},{"year":2012,"finding":"Sp2 binds GC-boxes and occupies proximal promoters of genes required for gene expression, replication, metabolism and signalling; it activates transcription factor and co-activator genes and represses the entire battery of cholesterol synthesis genes. Sp2 is required for cellular proliferation.","method":"ChIP-seq, RNA interference, in vitro DNA binding assays, global gene-expression profiling","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP-seq combined with RNAi knockdown and transcriptome profiling, multiple orthogonal methods in single lab","pmids":["22684502"],"is_preprint":false},{"year":2004,"finding":"Sp2 binds the CEACAM1 promoter in vitro and in vivo, represses CEACAM1 transcription by recruiting histone deacetylase activity to the promoter, and overexpression of Sp2 down-regulates endogenous CEACAM1 in normal prostate epithelial cells.","method":"In vitro DNA binding, chromatin immunoprecipitation, transient overexpression, siRNA knockdown, HDAC activity assay","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal ChIP, in vitro binding, overexpression/knockdown with mechanistic readout (HDAC recruitment), multiple orthogonal methods","pmids":["15126343"],"is_preprint":false},{"year":2006,"finding":"SP2 and KLF6 form a repressor complex on the MMP-9 promoter to maintain its silenced state; upon FXR activation, SHP interacts with SP2 and KLF6 and disrupts this repressor complex, enabling MMP-9 up-regulation and endothelial cell migration.","method":"siRNA silencing, promoter reporter assays, gel shift assays, chromatin immunoprecipitation, gain- and loss-of-function approaches","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP, EMSA, promoter assays, and siRNA combined with functional readout; multiple orthogonal methods in single study","pmids":["17071613"],"is_preprint":false},{"year":2004,"finding":"Sp2 DNA-binding consensus sequence is 5'-GGGCGGGAC-3' and Sp2 binds this sequence with high affinity (Kd ~225 pM) in vitro; however, Sp2 DNA-binding activity and trans-activation are negatively regulated in mammalian cells, and Sp2 is a relatively weak trans-activator with little capacity for additive or synergistic activation.","method":"PCR-based consensus determination, kinetic binding assays (in vitro), chimeric Sp1/Sp2 constructs, transient co-transfection with DHFR promoter reporter","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro binding with affinity measurement, mutagenesis of promoter elements, chimeric protein analysis; multiple orthogonal methods","pmids":["14726517"],"is_preprint":false},{"year":2006,"finding":"Sp2 localizes to subnuclear foci associated with the nuclear matrix; a 37 amino acid sequence spanning the first zinc finger is sufficient to direct nuclear matrix association and also encodes a bipartite nuclear localization sequence. A second nuclear matrix targeting sequence is within the Sp2 trans-activation domain.","method":"Nuclear fractionation, live-cell imaging, deletion analysis with GFP-tagged chimeric proteins, immunofluorescence","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct subcellular fractionation with functional domain deletion analysis and live imaging; multiple orthogonal methods in single lab","pmids":["16467376"],"is_preprint":false},{"year":2010,"finding":"Sp2 is essential for early mouse development (constitutive knockout lethal before E9.5 with severe growth retardation) and for autonomous proliferation of mouse embryonic fibroblasts; conditional ablation of Sp2 in MEFs strongly impairs cell proliferation. Sp2 has a non-redundant function distinct from Sp1, Sp3, and Sp4.","method":"Conditional and constitutive knockout mouse models (tri-loxP strategy, Cre-mediated ablation), MEF proliferation assays, whole-mount in situ hybridization","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO in mouse with clearly defined cellular phenotype (lethality, proliferation failure); replicated with both constitutive and conditional alleles","pmids":["20221402"],"is_preprint":false},{"year":2009,"finding":"Zebrafish Sp2 is maternally inherited, localizes to the nuclear matrix in a DNA-independent fashion, and is required for completion of gastrulation; knockdown phenotype establishes a role in early embryonic development.","method":"Zebrafish morpholino knockdown, RT-PCR expression analysis, GFP reporter transgenic lines, in vitro transcription assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — morpholino KD with developmental phenotype and nuclear localization assay; single lab, limited mechanistic depth beyond localization and developmental requirement","pmids":["19959469"],"is_preprint":false},{"year":2010,"finding":"Transgenic overexpression of Sp2 in epidermal basal keratinocytes in mice causes arrest of the epidermal differentiation program (homozygous animals perish within 2 weeks), increased susceptibility to wound- and carcinogen-induced papillomagenesis, and Sp2 protein levels increase with carcinogen-induced squamous cell carcinoma progression.","method":"Transgenic mouse overexpression (hemizygous and homozygous), carcinogen treatment, histological analysis","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct in vivo gain-of-function with clear differentiation and tumorigenesis phenotypes; two transgene doses tested; single lab","pmids":["20959487"],"is_preprint":false},{"year":2016,"finding":"Sp2 directly binds to GC-box/Sp-binding motifs in the human RORγT promoter and is required for maintaining RORγT expression; Sp2 is necessary for maximal IL-17 expression in in vitro-differentiated Th17 cells.","method":"Promoter activity assays, in situ mutagenesis, chromatin immunoprecipitation, siRNA knockdown, real-time RT-PCR in human lymphocytic cell line and differentiated Th17 cells","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, mutagenesis, and siRNA with functional readout; single lab, multiple orthogonal methods","pmids":["27256574"],"is_preprint":false},{"year":2020,"finding":"Loss of Sp2 in cortical progenitors undergoing neurogenic divisions results in prolonged mitosis due to extension of early mitotic stages, and depletion of upper layer neurons; early cortical neural stem cells expand normally without Sp2, indicating a stage-specific requirement.","method":"Conditional genetic deletion in mice combined with MADM (mosaic analysis with double markers), cell cycle analysis, neuronal layer quantification","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with MADM for clonal analysis; specific mitotic phenotype identified; single lab","pmids":["32001437"],"is_preprint":false},{"year":2019,"finding":"The 9aaTAD transactivation domain in Sp2 was inactivated early in chordate evolution by accumulation of valine residues; Sp2 secondary 9aaTADs are encoded in introns from fish to primates, and in the gibbon genome such intron-9aaTADs are used as exons, converting Sp2 into a transcriptional activator. Amino acid substitutions showed that glutamine residues are dispensable for 9aaTAD function.","method":"Amino acid substitution analysis, comparative genomics, transactivation reporter assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — mutagenesis combined with evolutionary sequence analysis and reporter assays; single lab","pmids":["31375868"],"is_preprint":false},{"year":2005,"finding":"Sp2 protein present in muscle cell nuclear extracts binds a specific site in the mouse Id3 proximal promoter in vitro; mutation of this Sp2 site substantially reduces Id3 promoter activity in proliferating muscle cells, and protein binding to this site is markedly reduced in differentiated muscle cells.","method":"DNase I footprinting, EMSA, promoter mutagenesis, nuclear extract binding assays with Sp2 antibody supershift","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA with antibody supershift, promoter mutagenesis, functional correlation with differentiation state; single lab","pmids":["16216350"],"is_preprint":false},{"year":2021,"finding":"Sp2 transcription factor directly binds the promoter regions of MMP2, MMP9, and VE-cadherin to promote their transcription, thereby regulating vasculogenic mimicry formation in glioma cells. Sp2 expression is regulated upstream by miR-651-3p targeting its 3'-UTR.","method":"ChIP assay, luciferase reporter assay, siRNA knockdown, transwell/VM formation assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP and reporter assay for direct promoter binding, functional knockdown; single lab","pmids":["33542193"],"is_preprint":false},{"year":2021,"finding":"Sp2 directly binds the promoter region of miR-195-5p to repress its expression; reduced Sp2 in bicuspid aortic valve interstitial cells increases SMAD7 expression and attenuates Smad2/3 signaling, promoting osteogenic differentiation through a SMAD-dependent pathway.","method":"ChIP assay, cotransfection with SP2 shRNA and miR-195-5p mimic, western blot, immunofluorescence in porcine VICs","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP for direct promoter binding, functional rescue with miR-195-5p; single lab, single tissue model","pmids":["34914964"],"is_preprint":false},{"year":2023,"finding":"Sp2, activated downstream of AMPK, directly binds the NEAT1 promoter to induce its expression; this forms a LTF/AMPK/SP2/NEAT1/miR-214-5p positive feedback loop promoting radioresistance via autophagy in lung squamous cell carcinoma.","method":"ChIP assay, luciferase reporter assay, co-immunoprecipitation (LTF-AMPK), siRNA knockdown, functional radioresistance assays","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP for direct promoter binding of SP2, Co-IP for upstream AMPK interaction, functional assays; single lab","pmids":["37056929"],"is_preprint":false},{"year":2024,"finding":"Sp2 promotes the transcription of the Vdac2 gene by directly binding to its promoter; this Sp2/VDAC2 axis mediates DBP-induced ferroptosis in mouse Leydig cells.","method":"ChIP assay, promoter reporter assay, siRNA knockdown, western blot, ferroptosis assays","journal":"Environmental research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — ChIP and reporter assay for promoter binding; single lab, limited mechanistic depth","pmids":["38246300"],"is_preprint":false},{"year":2021,"finding":"SP2 regulates ANLN (Anillin) expression by binding to its promoter; SP2-mediated ANLN upregulation promotes colorectal carcinoma cell proliferation via PI3K/AKT and MAPK pathways.","method":"Chromatin immunoprecipitation, luciferase reporter assay, siRNA knockdown, CCK-8, colony formation, mouse xenograft model","journal":"Journal of investigative surgery","confidence":"Low","confidence_rationale":"Tier 3 / Weak — ChIP and reporter for promoter binding; single lab; downstream pathway inferred from phosphorylation levels","pmids":["33757382"],"is_preprint":false},{"year":2000,"finding":"Sp2 represses Sp1- and Sp3-driven transcription of the CTα gene in Drosophila SL2 cells but stimulates transcription in mammalian C3H10T1/2 cells, acting through specific cis-acting GC-rich elements; effectiveness depends on cellular background and organization of three cis-acting elements.","method":"Transient transfections, promoter mutation analysis, electromobility gel shifts, immunoblot","journal":"Journal of lipid research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA, transfection reporter assays with mutants, cell-context comparison; multiple orthogonal methods; single lab","pmids":["10744779"],"is_preprint":false},{"year":2005,"finding":"Sp1 and Sp2 transcription factors bind to GC-rich elements in the SULT2B1b promoter and 5'-UTR, inducing reporter gene activity; this induction is markedly augmented by histone deacetylase inhibition.","method":"Supershift EMSA (identifying Sp1 and Sp2 binding), reporter assays, HDAC inhibitor treatment","journal":"FEBS letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — supershift EMSA identifies Sp2 binding; reporter assays show functional effect; single lab, limited follow-up on Sp2 specifically","pmids":["15953604"],"is_preprint":false},{"year":2010,"finding":"Sp2 transcription is regulated by at least two promoters with differing cell-type specificity; the 5'-UTR undergoes alternative splicing; sub-genomic mRNAs capable of encoding a partial-Sp2 protein are produced in a tissue- and cell-type-specific manner; Sp2 is widely expressed in embryonic brain and neurogenic regions of postnatal brain.","method":"cDNA cloning, RT-PCR, promoter deletion analysis in cell lines, RNA in situ hybridization","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter deletion analysis with multiple cell lines and in situ hybridization; single lab, several orthogonal methods","pmids":["20353838"],"is_preprint":false},{"year":2024,"finding":"CD93 interacts with MMRN2 and integrin β1; knockdown of CD93 inhibits activation of integrin β1, thereby suppressing the PI3K/AKT/SP2 signaling pathway and inhibiting breast cancer cell vasculogenic mimicry. Overexpression of SP2 rescues the effects of CD93 knockdown.","method":"Co-immunoprecipitation, siRNA knockdown, lentiviral overexpression, western blot, in vivo xenograft model","journal":"Journal of biochemical and molecular toxicology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — Co-IP for protein interactions, functional rescue with SP2 overexpression; SP2 placed downstream of PI3K/AKT but mechanism of SP2 activation not established; single lab","pmids":["38511888"],"is_preprint":false},{"year":2021,"finding":"Src-1 interacts with SP2 protein (co-immunoprecipitation) and together they regulate EMT-related genes (E-cadherin, N-cadherin, vimentin, ZEB1) and apoptosis/proliferation genes in nasopharyngeal carcinoma cells; SP2 knockdown reverses the pro-tumorigenic effects of Src-1 overexpression.","method":"Co-immunoprecipitation, siRNA knockdown, overexpression, western blot, CCK-8, transwell assays","journal":"Open medicine (Warsaw, Poland)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP for Src-1/SP2 interaction; functional epistasis by double knockdown/overexpression; single lab","pmids":["34307888"],"is_preprint":false}],"current_model":"SP2 (Specificity Protein 2) is a transcription factor that localizes to the nuclear matrix via its first zinc finger region and recruits target promoters primarily through its glutamine-rich N-terminal domain rather than direct zinc-finger DNA binding; it is tethered to CCAAT-containing promoters via a complex with the histone-fold protein Nf-y and TALE homeoproteins Pbx1:Prep1, potentiating their chromatin binding at composite motifs, while at GC-box elements it can directly bind and repress target genes (e.g., cholesterol synthesis genes, CEACAM1) partly through HDAC recruitment; Sp2 is essential for early mouse embryonic development and for cell proliferation in MEFs, and regulates neurogenic but not expansive divisions of cortical neural stem cells, with its transactivation domain having been inactivated in early chordates through accumulation of valine residues in its 9aaTAD motif."},"narrative":{"mechanistic_narrative":"SP2 is a Sp/KLF-family transcription factor that controls genes governing proliferation, metabolism, and cell-fate transitions, and is essential for early mammalian development [PMID:22684502, PMID:20221402]. Unlike its paralogs, SP2 engages chromatin largely through protein-protein recruitment rather than autonomous zinc-finger DNA binding: its glutamine-rich N-terminal region, acting through an Sp-box motif, recruits the histone-fold factor Nf-y to CCAAT motifs genome-wide and reciprocally potentiates Nf-y binding [PMID:25793500, PMID:30337366]. At composite regulatory elements SP2 is tethered to a TALE homeoprotein complex of Pbx1:Prep1 together with Nf-y, again with mutual potentiation of chromatin occupancy [PMID:30337366]. SP2 also binds GC-box/Sp consensus sites directly (consensus 5'-GGGCGGGAC-3'), where it occupies proximal promoters of genes for transcription, replication, and metabolism, activating some targets while repressing others such as the cholesterol-synthesis battery [PMID:22684502, PMID:14726517]. Direct repression can proceed through recruitment of histone deacetylase activity, as shown at the CEACAM1 promoter [PMID:15126343]. SP2 localizes to nuclear-matrix-associated subnuclear foci via a sequence spanning its first zinc finger that also encodes a bipartite nuclear localization signal [PMID:16467376]. Genetically, SP2 is required for autonomous proliferation of fibroblasts and for the neurogenic (but not expansive) divisions of cortical neural stem cells, where its loss prolongs mitosis [PMID:20221402, PMID:32001437]. Its 9aaTAD transactivation domain was inactivated early in chordate evolution by valine accumulation, rendering SP2 a relatively weak trans-activator in mammals [PMID:14726517, PMID:31375868].","teleology":[{"year":2000,"claim":"Established that SP2 acts on GC-rich cis-elements with context-dependent outcomes, raising the question of whether it activates or represses transcription.","evidence":"transient transfection, promoter mutation, and EMSA comparing Drosophila SL2 and mammalian cells on the CTα gene","pmids":["10744779"],"confidence":"Medium","gaps":["Mechanism underlying cell-context switch between repression and activation not defined","No genome-wide target mapping"]},{"year":2004,"claim":"Defined SP2's high-affinity DNA consensus and showed its intrinsic trans-activation is weak and negatively regulated, distinguishing it from strong activators like Sp1.","evidence":"PCR-based consensus selection, kinetic binding assays, chimeric Sp1/Sp2 constructs, and DHFR reporter assays in vitro and in mammalian cells","pmids":["14726517"],"confidence":"High","gaps":["Identity of the negative regulator of DNA-binding/activation unknown","Endogenous direct targets not defined"]},{"year":2004,"claim":"Provided a concrete repressive mechanism, showing SP2 silences a target promoter by recruiting HDAC activity.","evidence":"reciprocal ChIP, in vitro binding, overexpression/knockdown, and HDAC activity assay at the CEACAM1 promoter in prostate epithelial cells","pmids":["15126343"],"confidence":"High","gaps":["Specific HDAC isoform and corepressor adaptors not identified","Generality of HDAC recruitment across other SP2 targets not tested"]},{"year":2006,"claim":"Localized SP2 to the nuclear matrix and mapped the domains responsible, linking its first zinc finger to subnuclear targeting and nuclear import.","evidence":"nuclear fractionation, live-cell imaging, and GFP deletion-chimera analysis","pmids":["16467376"],"confidence":"High","gaps":["Functional consequence of nuclear-matrix association for transcription not established","Matrix-anchoring partner proteins unknown"]},{"year":2006,"claim":"Showed SP2 participates in a multiprotein repressor complex regulated by hormone signaling, framing it as a node in inducible gene control.","evidence":"siRNA, reporter, EMSA, and ChIP on the MMP-9 promoter with FXR/SHP/KLF6 perturbation","pmids":["17071613"],"confidence":"High","gaps":["Direct SP2-KLF6 interaction surface not mapped","Whether SP2 is the DNA-anchoring subunit of the complex unclear"]},{"year":2010,"claim":"Established SP2 as non-redundant and essential, demonstrating an organismal and cell-autonomous proliferative requirement distinct from other Sp factors.","evidence":"constitutive and conditional knockout mouse models with MEF proliferation assays and in situ hybridization","pmids":["20221402"],"confidence":"High","gaps":["Molecular targets mediating the proliferation defect not pinpointed","Cause of pre-E9.5 lethality at the pathway level undefined"]},{"year":2012,"claim":"Mapped the genome-wide GC-box occupancy and transcriptional output of SP2, revealing a dual activator/repressor role and direct control of cholesterol synthesis genes.","evidence":"ChIP-seq, RNAi, in vitro binding, and transcriptome profiling","pmids":["22684502"],"confidence":"High","gaps":["How activation versus repression is selected at each promoter not resolved","Coactivator/corepressor partners genome-wide not catalogued"]},{"year":2015,"claim":"Resolved that SP2 binds CCAAT motifs not via its zinc fingers but through its glutamine-rich N-terminus recruiting Nf-y, redefining its mode of chromatin engagement.","evidence":"ChIP-seq with zinc-finger mutant rescue in matched KO MEFs and co-occupancy analysis","pmids":["25793500"],"confidence":"High","gaps":["Direct vs. bridged contact between SP2 N-terminus and Nf-y not structurally defined","Functional output of CCAAT co-occupancy on target genes incomplete"]},{"year":2018,"claim":"Extended the cofactor model to composite TALE+CCAAT elements, showing SP2 forms and potentiates a Pbx1:Prep1-Nf-y complex via its Sp-box.","evidence":"ChIP-exo, reciprocal Co-IP, and domain deletion/mutation in MEFs","pmids":["30337366"],"confidence":"High","gaps":["Stoichiometry and architecture of the SP2-Pbx1:Prep1-Nf-y assembly unknown","Target genes regulated by composite sites not enumerated"]},{"year":2019,"claim":"Explained why mammalian SP2 is a weak activator, attributing it to evolutionary inactivation of its 9aaTAD by valine accumulation.","evidence":"amino-acid substitution analysis, comparative genomics, and transactivation reporter assays","pmids":["31375868"],"confidence":"Medium","gaps":["Whether intron-encoded 9aaTADs are used in any normal human context untested","Link between weak TAD and the recruitment-based mechanism not directly probed"]},{"year":2020,"claim":"Defined a stage-specific developmental role, showing SP2 is required for neurogenic divisions and timely mitotic progression in cortical progenitors.","evidence":"conditional deletion with MADM clonal analysis, cell-cycle analysis, and neuronal layer quantification in mice","pmids":["32001437"],"confidence":"Medium","gaps":["Mitotic targets of SP2 driving the prolonged mitosis not identified","Why expansive divisions are SP2-independent unexplained"]},{"year":null,"claim":"It remains unresolved how SP2 selects activation versus repression at individual promoters and which corepressor/coactivator and matrix-anchoring partners convert its weak-TAD, recruitment-based binding into specific transcriptional outputs.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of SP2 with Nf-y or Pbx1:Prep1","Direct effectors of the proliferation and mitotic phenotypes unknown","Many cancer-context targets rest on single-lab ChIP/reporter evidence without reciprocal validation"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[2,3,5,12]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[2,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[6,8]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,2,3]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[7,11]}],"complexes":[],"partners":["NFYA","PBX1","PREP1","KLF6","SHP"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q02086","full_name":"Transcription factor Sp2","aliases":[],"length_aa":613,"mass_kda":64.9,"function":"Binds to GC box promoters elements and selectively activates mRNA synthesis from genes that contain functional recognition sites","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q02086/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SP2","classification":"Not Classified","n_dependent_lines":195,"n_total_lines":1208,"dependency_fraction":0.16142384105960264},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SP2","total_profiled":1310},"omim":[{"mim_id":"614475","title":"ATRIAL SEPTAL DEFECT 9; ASD9","url":"https://www.omim.org/entry/614475"},{"mim_id":"614474","title":"ATRIOVENTRICULAR SEPTAL DEFECT 5; AVSD5","url":"https://www.omim.org/entry/614474"},{"mim_id":"603496","title":"DUAL-SPECIFICITY TYROSINE PHOSPHORYLATION-REGULATED KINASE 2; DYRK2","url":"https://www.omim.org/entry/603496"},{"mim_id":"603073","title":"ZIC FAMILY, MEMBER 2; ZIC2","url":"https://www.omim.org/entry/603073"},{"mim_id":"601804","title":"TRANSCRIPTION FACTOR Sp3; SP3","url":"https://www.omim.org/entry/601804"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SP2"},"hgnc":{"alias_symbol":["KIAA0048"],"prev_symbol":[]},"alphafold":{"accession":"Q02086","domains":[{"cath_id":"3.30.160","chopping":"583-613","consensus_level":"medium","plddt":81.2406,"start":583,"end":613}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q02086","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q02086-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q02086-F1-predicted_aligned_error_v6.png","plddt_mean":44.47},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SP2","jax_strain_url":"https://www.jax.org/strain/search?query=SP2"},"sequence":{"accession":"Q02086","fasta_url":"https://rest.uniprot.org/uniprotkb/Q02086.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q02086/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q02086"}},"corpus_meta":[{"pmid":"17002342","id":"PMC_17002342","title":"Palladium-catalyzed alkylation of sp2 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Part D, Genomics & proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/23299360","citation_count":9,"is_preprint":false},{"pmid":"10890152","id":"PMC_10890152","title":"sp2-bridged diaryl retinoids: effects of bridge-region substitution on retinoid X receptor (RXR) selectivity.","date":"2000","source":"Bioorganic & medicinal chemistry letters","url":"https://pubmed.ncbi.nlm.nih.gov/10890152","citation_count":9,"is_preprint":false},{"pmid":"38246300","id":"PMC_38246300","title":"Melatonin alleviates di-butyl phthalate (DBP)-induced ferroptosis of mouse leydig cells via inhibiting Sp2/VDAC2 signals.","date":"2024","source":"Environmental research","url":"https://pubmed.ncbi.nlm.nih.gov/38246300","citation_count":8,"is_preprint":false},{"pmid":"35228567","id":"PMC_35228567","title":"Comparative systeomics to elucidate physiological differences between CHO and SP2/0 cell lines.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35228567","citation_count":7,"is_preprint":false},{"pmid":"1500885","id":"PMC_1500885","title":"Xenopus laevis sperm proteins, previously identified as surface proteins with egg coat binding capability, are indeed histone H4, histone H3, and sperm specific protein SP2.","date":"1992","source":"The Journal of experimental zoology","url":"https://pubmed.ncbi.nlm.nih.gov/1500885","citation_count":7,"is_preprint":false},{"pmid":"34307888","id":"PMC_34307888","title":"Src-1 and SP2 promote the proliferation and epithelial-mesenchymal transition of nasopharyngeal carcinoma.","date":"2021","source":"Open medicine (Warsaw, Poland)","url":"https://pubmed.ncbi.nlm.nih.gov/34307888","citation_count":6,"is_preprint":false},{"pmid":"33397093","id":"PMC_33397093","title":"Strategy for Selective Csp2-F and Csp2-Csp2 Formations from Organoplatinum Complexes.","date":"2021","source":"Inorganic chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/33397093","citation_count":6,"is_preprint":false},{"pmid":"12745987","id":"PMC_12745987","title":"Effects of brevetoxins on murine myeloma SP2/O cells: aberrant cellular division.","date":"2003","source":"International journal of toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/12745987","citation_count":6,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":46944,"output_tokens":5654,"usd":0.112821,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14279,"output_tokens":3552,"usd":0.080098,"stage2_stop_reason":"end_turn"},"total_usd":0.192919,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"Sp2 binds to CCAAT motifs genome-wide in mouse embryonic fibroblasts via its glutamine-rich amino-terminal region, independently of its zinc finger domain, and recruits the histone-fold CCAAT-binding factor Nf-y; Nf-y is critical for recruitment of Sp2 to co-occupied regulatory elements, and reciprocally Sp2 potentiates Nf-y binding at shared sites.\",\n      \"method\": \"ChIP-seq in MEFs; re-expression of Sp2/Sp3 zinc finger mutants in corresponding knockout MEFs; co-occupancy analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq with mutant rescue in matched KO MEFs, multiple orthogonal methods (ChIP-seq, mutant re-expression, motif analysis), single lab but rigorous design\",\n      \"pmids\": [\"25793500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Sp2 is recruited to composite genomic sites containing a TALE homeoprotein recognition sequence and an Nf-y recognition sequence separated by ~11 bp; a complex of Pbx1:Prep1 and Nf-y recruits Sp2 to co-occupied regulatory elements, and in turn Sp2 potentiates binding of Pbx1:Prep1 and Nf-y. The Sp-box motif near the Sp2 N-terminus is required for this cofactor function.\",\n      \"method\": \"ChIP-exo sequencing in MEFs; co-immunoprecipitation; domain deletion/mutation analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-exo with mutational follow-up, reciprocal Co-IP, composite motif identification, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"30337366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Sp2 binds GC-boxes and occupies proximal promoters of genes required for gene expression, replication, metabolism and signalling; it activates transcription factor and co-activator genes and represses the entire battery of cholesterol synthesis genes. Sp2 is required for cellular proliferation.\",\n      \"method\": \"ChIP-seq, RNA interference, in vitro DNA binding assays, global gene-expression profiling\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq combined with RNAi knockdown and transcriptome profiling, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"22684502\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Sp2 binds the CEACAM1 promoter in vitro and in vivo, represses CEACAM1 transcription by recruiting histone deacetylase activity to the promoter, and overexpression of Sp2 down-regulates endogenous CEACAM1 in normal prostate epithelial cells.\",\n      \"method\": \"In vitro DNA binding, chromatin immunoprecipitation, transient overexpression, siRNA knockdown, HDAC activity assay\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal ChIP, in vitro binding, overexpression/knockdown with mechanistic readout (HDAC recruitment), multiple orthogonal methods\",\n      \"pmids\": [\"15126343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"SP2 and KLF6 form a repressor complex on the MMP-9 promoter to maintain its silenced state; upon FXR activation, SHP interacts with SP2 and KLF6 and disrupts this repressor complex, enabling MMP-9 up-regulation and endothelial cell migration.\",\n      \"method\": \"siRNA silencing, promoter reporter assays, gel shift assays, chromatin immunoprecipitation, gain- and loss-of-function approaches\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, EMSA, promoter assays, and siRNA combined with functional readout; multiple orthogonal methods in single study\",\n      \"pmids\": [\"17071613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Sp2 DNA-binding consensus sequence is 5'-GGGCGGGAC-3' and Sp2 binds this sequence with high affinity (Kd ~225 pM) in vitro; however, Sp2 DNA-binding activity and trans-activation are negatively regulated in mammalian cells, and Sp2 is a relatively weak trans-activator with little capacity for additive or synergistic activation.\",\n      \"method\": \"PCR-based consensus determination, kinetic binding assays (in vitro), chimeric Sp1/Sp2 constructs, transient co-transfection with DHFR promoter reporter\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro binding with affinity measurement, mutagenesis of promoter elements, chimeric protein analysis; multiple orthogonal methods\",\n      \"pmids\": [\"14726517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Sp2 localizes to subnuclear foci associated with the nuclear matrix; a 37 amino acid sequence spanning the first zinc finger is sufficient to direct nuclear matrix association and also encodes a bipartite nuclear localization sequence. A second nuclear matrix targeting sequence is within the Sp2 trans-activation domain.\",\n      \"method\": \"Nuclear fractionation, live-cell imaging, deletion analysis with GFP-tagged chimeric proteins, immunofluorescence\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular fractionation with functional domain deletion analysis and live imaging; multiple orthogonal methods in single lab\",\n      \"pmids\": [\"16467376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Sp2 is essential for early mouse development (constitutive knockout lethal before E9.5 with severe growth retardation) and for autonomous proliferation of mouse embryonic fibroblasts; conditional ablation of Sp2 in MEFs strongly impairs cell proliferation. Sp2 has a non-redundant function distinct from Sp1, Sp3, and Sp4.\",\n      \"method\": \"Conditional and constitutive knockout mouse models (tri-loxP strategy, Cre-mediated ablation), MEF proliferation assays, whole-mount in situ hybridization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO in mouse with clearly defined cellular phenotype (lethality, proliferation failure); replicated with both constitutive and conditional alleles\",\n      \"pmids\": [\"20221402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Zebrafish Sp2 is maternally inherited, localizes to the nuclear matrix in a DNA-independent fashion, and is required for completion of gastrulation; knockdown phenotype establishes a role in early embryonic development.\",\n      \"method\": \"Zebrafish morpholino knockdown, RT-PCR expression analysis, GFP reporter transgenic lines, in vitro transcription assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — morpholino KD with developmental phenotype and nuclear localization assay; single lab, limited mechanistic depth beyond localization and developmental requirement\",\n      \"pmids\": [\"19959469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Transgenic overexpression of Sp2 in epidermal basal keratinocytes in mice causes arrest of the epidermal differentiation program (homozygous animals perish within 2 weeks), increased susceptibility to wound- and carcinogen-induced papillomagenesis, and Sp2 protein levels increase with carcinogen-induced squamous cell carcinoma progression.\",\n      \"method\": \"Transgenic mouse overexpression (hemizygous and homozygous), carcinogen treatment, histological analysis\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct in vivo gain-of-function with clear differentiation and tumorigenesis phenotypes; two transgene doses tested; single lab\",\n      \"pmids\": [\"20959487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Sp2 directly binds to GC-box/Sp-binding motifs in the human RORγT promoter and is required for maintaining RORγT expression; Sp2 is necessary for maximal IL-17 expression in in vitro-differentiated Th17 cells.\",\n      \"method\": \"Promoter activity assays, in situ mutagenesis, chromatin immunoprecipitation, siRNA knockdown, real-time RT-PCR in human lymphocytic cell line and differentiated Th17 cells\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, mutagenesis, and siRNA with functional readout; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"27256574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of Sp2 in cortical progenitors undergoing neurogenic divisions results in prolonged mitosis due to extension of early mitotic stages, and depletion of upper layer neurons; early cortical neural stem cells expand normally without Sp2, indicating a stage-specific requirement.\",\n      \"method\": \"Conditional genetic deletion in mice combined with MADM (mosaic analysis with double markers), cell cycle analysis, neuronal layer quantification\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with MADM for clonal analysis; specific mitotic phenotype identified; single lab\",\n      \"pmids\": [\"32001437\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The 9aaTAD transactivation domain in Sp2 was inactivated early in chordate evolution by accumulation of valine residues; Sp2 secondary 9aaTADs are encoded in introns from fish to primates, and in the gibbon genome such intron-9aaTADs are used as exons, converting Sp2 into a transcriptional activator. Amino acid substitutions showed that glutamine residues are dispensable for 9aaTAD function.\",\n      \"method\": \"Amino acid substitution analysis, comparative genomics, transactivation reporter assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mutagenesis combined with evolutionary sequence analysis and reporter assays; single lab\",\n      \"pmids\": [\"31375868\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Sp2 protein present in muscle cell nuclear extracts binds a specific site in the mouse Id3 proximal promoter in vitro; mutation of this Sp2 site substantially reduces Id3 promoter activity in proliferating muscle cells, and protein binding to this site is markedly reduced in differentiated muscle cells.\",\n      \"method\": \"DNase I footprinting, EMSA, promoter mutagenesis, nuclear extract binding assays with Sp2 antibody supershift\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA with antibody supershift, promoter mutagenesis, functional correlation with differentiation state; single lab\",\n      \"pmids\": [\"16216350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Sp2 transcription factor directly binds the promoter regions of MMP2, MMP9, and VE-cadherin to promote their transcription, thereby regulating vasculogenic mimicry formation in glioma cells. Sp2 expression is regulated upstream by miR-651-3p targeting its 3'-UTR.\",\n      \"method\": \"ChIP assay, luciferase reporter assay, siRNA knockdown, transwell/VM formation assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP and reporter assay for direct promoter binding, functional knockdown; single lab\",\n      \"pmids\": [\"33542193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Sp2 directly binds the promoter region of miR-195-5p to repress its expression; reduced Sp2 in bicuspid aortic valve interstitial cells increases SMAD7 expression and attenuates Smad2/3 signaling, promoting osteogenic differentiation through a SMAD-dependent pathway.\",\n      \"method\": \"ChIP assay, cotransfection with SP2 shRNA and miR-195-5p mimic, western blot, immunofluorescence in porcine VICs\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP for direct promoter binding, functional rescue with miR-195-5p; single lab, single tissue model\",\n      \"pmids\": [\"34914964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Sp2, activated downstream of AMPK, directly binds the NEAT1 promoter to induce its expression; this forms a LTF/AMPK/SP2/NEAT1/miR-214-5p positive feedback loop promoting radioresistance via autophagy in lung squamous cell carcinoma.\",\n      \"method\": \"ChIP assay, luciferase reporter assay, co-immunoprecipitation (LTF-AMPK), siRNA knockdown, functional radioresistance assays\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP for direct promoter binding of SP2, Co-IP for upstream AMPK interaction, functional assays; single lab\",\n      \"pmids\": [\"37056929\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Sp2 promotes the transcription of the Vdac2 gene by directly binding to its promoter; this Sp2/VDAC2 axis mediates DBP-induced ferroptosis in mouse Leydig cells.\",\n      \"method\": \"ChIP assay, promoter reporter assay, siRNA knockdown, western blot, ferroptosis assays\",\n      \"journal\": \"Environmental research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — ChIP and reporter assay for promoter binding; single lab, limited mechanistic depth\",\n      \"pmids\": [\"38246300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SP2 regulates ANLN (Anillin) expression by binding to its promoter; SP2-mediated ANLN upregulation promotes colorectal carcinoma cell proliferation via PI3K/AKT and MAPK pathways.\",\n      \"method\": \"Chromatin immunoprecipitation, luciferase reporter assay, siRNA knockdown, CCK-8, colony formation, mouse xenograft model\",\n      \"journal\": \"Journal of investigative surgery\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — ChIP and reporter for promoter binding; single lab; downstream pathway inferred from phosphorylation levels\",\n      \"pmids\": [\"33757382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Sp2 represses Sp1- and Sp3-driven transcription of the CTα gene in Drosophila SL2 cells but stimulates transcription in mammalian C3H10T1/2 cells, acting through specific cis-acting GC-rich elements; effectiveness depends on cellular background and organization of three cis-acting elements.\",\n      \"method\": \"Transient transfections, promoter mutation analysis, electromobility gel shifts, immunoblot\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA, transfection reporter assays with mutants, cell-context comparison; multiple orthogonal methods; single lab\",\n      \"pmids\": [\"10744779\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Sp1 and Sp2 transcription factors bind to GC-rich elements in the SULT2B1b promoter and 5'-UTR, inducing reporter gene activity; this induction is markedly augmented by histone deacetylase inhibition.\",\n      \"method\": \"Supershift EMSA (identifying Sp1 and Sp2 binding), reporter assays, HDAC inhibitor treatment\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — supershift EMSA identifies Sp2 binding; reporter assays show functional effect; single lab, limited follow-up on Sp2 specifically\",\n      \"pmids\": [\"15953604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Sp2 transcription is regulated by at least two promoters with differing cell-type specificity; the 5'-UTR undergoes alternative splicing; sub-genomic mRNAs capable of encoding a partial-Sp2 protein are produced in a tissue- and cell-type-specific manner; Sp2 is widely expressed in embryonic brain and neurogenic regions of postnatal brain.\",\n      \"method\": \"cDNA cloning, RT-PCR, promoter deletion analysis in cell lines, RNA in situ hybridization\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter deletion analysis with multiple cell lines and in situ hybridization; single lab, several orthogonal methods\",\n      \"pmids\": [\"20353838\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CD93 interacts with MMRN2 and integrin β1; knockdown of CD93 inhibits activation of integrin β1, thereby suppressing the PI3K/AKT/SP2 signaling pathway and inhibiting breast cancer cell vasculogenic mimicry. Overexpression of SP2 rescues the effects of CD93 knockdown.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, lentiviral overexpression, western blot, in vivo xenograft model\",\n      \"journal\": \"Journal of biochemical and molecular toxicology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — Co-IP for protein interactions, functional rescue with SP2 overexpression; SP2 placed downstream of PI3K/AKT but mechanism of SP2 activation not established; single lab\",\n      \"pmids\": [\"38511888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Src-1 interacts with SP2 protein (co-immunoprecipitation) and together they regulate EMT-related genes (E-cadherin, N-cadherin, vimentin, ZEB1) and apoptosis/proliferation genes in nasopharyngeal carcinoma cells; SP2 knockdown reverses the pro-tumorigenic effects of Src-1 overexpression.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, overexpression, western blot, CCK-8, transwell assays\",\n      \"journal\": \"Open medicine (Warsaw, Poland)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for Src-1/SP2 interaction; functional epistasis by double knockdown/overexpression; single lab\",\n      \"pmids\": [\"34307888\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SP2 (Specificity Protein 2) is a transcription factor that localizes to the nuclear matrix via its first zinc finger region and recruits target promoters primarily through its glutamine-rich N-terminal domain rather than direct zinc-finger DNA binding; it is tethered to CCAAT-containing promoters via a complex with the histone-fold protein Nf-y and TALE homeoproteins Pbx1:Prep1, potentiating their chromatin binding at composite motifs, while at GC-box elements it can directly bind and repress target genes (e.g., cholesterol synthesis genes, CEACAM1) partly through HDAC recruitment; Sp2 is essential for early mouse embryonic development and for cell proliferation in MEFs, and regulates neurogenic but not expansive divisions of cortical neural stem cells, with its transactivation domain having been inactivated in early chordates through accumulation of valine residues in its 9aaTAD motif.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SP2 is a Sp/KLF-family transcription factor that controls genes governing proliferation, metabolism, and cell-fate transitions, and is essential for early mammalian development [#2, #7]. Unlike its paralogs, SP2 engages chromatin largely through protein-protein recruitment rather than autonomous zinc-finger DNA binding: its glutamine-rich N-terminal region, acting through an Sp-box motif, recruits the histone-fold factor Nf-y to CCAAT motifs genome-wide and reciprocally potentiates Nf-y binding [#0, #1]. At composite regulatory elements SP2 is tethered to a TALE homeoprotein complex of Pbx1:Prep1 together with Nf-y, again with mutual potentiation of chromatin occupancy [#1]. SP2 also binds GC-box/Sp consensus sites directly (consensus 5'-GGGCGGGAC-3'), where it occupies proximal promoters of genes for transcription, replication, and metabolism, activating some targets while repressing others such as the cholesterol-synthesis battery [#2, #5]. Direct repression can proceed through recruitment of histone deacetylase activity, as shown at the CEACAM1 promoter [#3]. SP2 localizes to nuclear-matrix-associated subnuclear foci via a sequence spanning its first zinc finger that also encodes a bipartite nuclear localization signal [#6]. Genetically, SP2 is required for autonomous proliferation of fibroblasts and for the neurogenic (but not expansive) divisions of cortical neural stem cells, where its loss prolongs mitosis [#7, #11]. Its 9aaTAD transactivation domain was inactivated early in chordate evolution by valine accumulation, rendering SP2 a relatively weak trans-activator in mammals [#5, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established that SP2 acts on GC-rich cis-elements with context-dependent outcomes, raising the question of whether it activates or represses transcription.\",\n      \"evidence\": \"transient transfection, promoter mutation, and EMSA comparing Drosophila SL2 and mammalian cells on the CT\\u03b1 gene\",\n      \"pmids\": [\"10744779\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism underlying cell-context switch between repression and activation not defined\", \"No genome-wide target mapping\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined SP2's high-affinity DNA consensus and showed its intrinsic trans-activation is weak and negatively regulated, distinguishing it from strong activators like Sp1.\",\n      \"evidence\": \"PCR-based consensus selection, kinetic binding assays, chimeric Sp1/Sp2 constructs, and DHFR reporter assays in vitro and in mammalian cells\",\n      \"pmids\": [\"14726517\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the negative regulator of DNA-binding/activation unknown\", \"Endogenous direct targets not defined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Provided a concrete repressive mechanism, showing SP2 silences a target promoter by recruiting HDAC activity.\",\n      \"evidence\": \"reciprocal ChIP, in vitro binding, overexpression/knockdown, and HDAC activity assay at the CEACAM1 promoter in prostate epithelial cells\",\n      \"pmids\": [\"15126343\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific HDAC isoform and corepressor adaptors not identified\", \"Generality of HDAC recruitment across other SP2 targets not tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Localized SP2 to the nuclear matrix and mapped the domains responsible, linking its first zinc finger to subnuclear targeting and nuclear import.\",\n      \"evidence\": \"nuclear fractionation, live-cell imaging, and GFP deletion-chimera analysis\",\n      \"pmids\": [\"16467376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of nuclear-matrix association for transcription not established\", \"Matrix-anchoring partner proteins unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed SP2 participates in a multiprotein repressor complex regulated by hormone signaling, framing it as a node in inducible gene control.\",\n      \"evidence\": \"siRNA, reporter, EMSA, and ChIP on the MMP-9 promoter with FXR/SHP/KLF6 perturbation\",\n      \"pmids\": [\"17071613\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct SP2-KLF6 interaction surface not mapped\", \"Whether SP2 is the DNA-anchoring subunit of the complex unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established SP2 as non-redundant and essential, demonstrating an organismal and cell-autonomous proliferative requirement distinct from other Sp factors.\",\n      \"evidence\": \"constitutive and conditional knockout mouse models with MEF proliferation assays and in situ hybridization\",\n      \"pmids\": [\"20221402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular targets mediating the proliferation defect not pinpointed\", \"Cause of pre-E9.5 lethality at the pathway level undefined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Mapped the genome-wide GC-box occupancy and transcriptional output of SP2, revealing a dual activator/repressor role and direct control of cholesterol synthesis genes.\",\n      \"evidence\": \"ChIP-seq, RNAi, in vitro binding, and transcriptome profiling\",\n      \"pmids\": [\"22684502\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How activation versus repression is selected at each promoter not resolved\", \"Coactivator/corepressor partners genome-wide not catalogued\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Resolved that SP2 binds CCAAT motifs not via its zinc fingers but through its glutamine-rich N-terminus recruiting Nf-y, redefining its mode of chromatin engagement.\",\n      \"evidence\": \"ChIP-seq with zinc-finger mutant rescue in matched KO MEFs and co-occupancy analysis\",\n      \"pmids\": [\"25793500\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs. bridged contact between SP2 N-terminus and Nf-y not structurally defined\", \"Functional output of CCAAT co-occupancy on target genes incomplete\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Extended the cofactor model to composite TALE+CCAAT elements, showing SP2 forms and potentiates a Pbx1:Prep1-Nf-y complex via its Sp-box.\",\n      \"evidence\": \"ChIP-exo, reciprocal Co-IP, and domain deletion/mutation in MEFs\",\n      \"pmids\": [\"30337366\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and architecture of the SP2-Pbx1:Prep1-Nf-y assembly unknown\", \"Target genes regulated by composite sites not enumerated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Explained why mammalian SP2 is a weak activator, attributing it to evolutionary inactivation of its 9aaTAD by valine accumulation.\",\n      \"evidence\": \"amino-acid substitution analysis, comparative genomics, and transactivation reporter assays\",\n      \"pmids\": [\"31375868\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether intron-encoded 9aaTADs are used in any normal human context untested\", \"Link between weak TAD and the recruitment-based mechanism not directly probed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined a stage-specific developmental role, showing SP2 is required for neurogenic divisions and timely mitotic progression in cortical progenitors.\",\n      \"evidence\": \"conditional deletion with MADM clonal analysis, cell-cycle analysis, and neuronal layer quantification in mice\",\n      \"pmids\": [\"32001437\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mitotic targets of SP2 driving the prolonged mitosis not identified\", \"Why expansive divisions are SP2-independent unexplained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how SP2 selects activation versus repression at individual promoters and which corepressor/coactivator and matrix-anchoring partners convert its weak-TAD, recruitment-based binding into specific transcriptional outputs.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of SP2 with Nf-y or Pbx1:Prep1\", \"Direct effectors of the proliferation and mitotic phenotypes unknown\", \"Many cancer-context targets rest on single-lab ChIP/reporter evidence without reciprocal validation\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [2, 3, 5, 12]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [6, 8]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [7, 11]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NFYA\", \"PBX1\", \"PREP1\", \"KLF6\", \"SHP\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}