{"gene":"GIPC2","run_date":"2026-04-28T18:06:52","timeline":{"discoveries":[{"year":2002,"finding":"GIPC2 was identified as a novel PDZ-domain protein (315 amino acids) with a central PDZ domain showing 62% amino acid identity to GIPC1, suggesting it may bind TGFβ type III receptor or Frizzled-class WNT receptors analogously to GIPC1/Kermit.","method":"Bioinformatics, cDNA cloning, sequence analysis","journal":"International journal of oncology","confidence":"Low","confidence_rationale":"Tier 4 — computational/sequence inference only; no direct binding experiment performed for GIPC2 itself","pmids":["11836570"],"is_preprint":false},{"year":2022,"finding":"GIPC2 directly binds the WNT co-receptor Frizzled-7 (Fzd7) through its PDZ domain, activating WNT-β-catenin signaling cascades and thereby promoting prostate cancer cell adhesion, invasion, and migration.","method":"Co-immunoprecipitation, PDZ domain mutagenesis, in vitro and in vivo functional assays (knockdown/overexpression)","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus domain-level mutagenesis plus in vivo tumor model with defined signaling readout","pmids":["35347223"],"is_preprint":false},{"year":2022,"finding":"GIPC2 protein is incorporated into tumor-derived exosomes and exosomal GIPC2 can stimulate prostate cancer cell adhesion, invasion, and migration in recipient cells.","method":"Exosome isolation, functional cell-based assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, exosome fractionation plus functional assay but no mechanistic detail of how exosomal GIPC2 acts","pmids":["35347223"],"is_preprint":false},{"year":2021,"finding":"GIPC2 interacts with the nuclear protein NONO, and together they regulate p27 transcription through the same GGCC box on the p27 promoter; GIPC2 also suppresses MAPK/ERK and HIF-1α pathways to inhibit chromaffin cell proliferation.","method":"Co-immunoprecipitation, promoter reporter/luciferase assays, overexpression in PC12 cells with nude mouse xenograft","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP plus promoter assay plus in vivo tumor model, single lab","pmids":["33947839"],"is_preprint":false},{"year":2021,"finding":"In rat adrenal chromaffin cells, RET- and SDHB-associated oncogenic mutations reduce GIPC2 expression to drive ERK activation and p27 downregulation, placing GIPC2 upstream of MAPK/ERK-p27 signaling in pheochromocytoma/paraganglioma pathogenesis; the RET-mutant effect on GIPC2 required dexamethasone (glucocorticoid), while SDHB-mutant effect required its absence.","method":"Genetic epistasis in primary rat adrenal chromaffin cells with RET/SDHB mutants, ERK phosphorylation and p27 immunoblotting","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis with defined signaling readout, single lab","pmids":["33947839"],"is_preprint":false},{"year":2012,"finding":"In Xenopus (kermit2/gipc2 ortholog), gipc2 depletion causes pronephros reduction and oedema; gipc2 binds the IGF receptor (IGFR) and this interaction is relevant to kidney morphogenesis; partial rescue by constitutively active PI3K p110* implicates GIPC2 in IGF-PI3K signaling during pronephros development.","method":"Morpholino knockdown in Xenopus, overexpression rescue with constitutively active PI3K, co-immunoprecipitation with IGFR","journal":"The International journal of developmental biology","confidence":"Medium","confidence_rationale":"Tier 2/3 — morpholino KD with clear phenotype and partial pathway rescue; ortholog context","pmids":["22689378"],"is_preprint":false},{"year":2023,"finding":"Overexpression of GIPC2 in AML HL-60 cells induces apoptosis by inhibiting the PI3K/AKT pathway; GIPC2 expression is silenced by promoter CpG methylation and restored by decitabine treatment.","method":"Overexpression in cell line, western blotting for AKT phosphorylation, bisulfite sequencing, decitabine treatment","journal":"Epigenomics","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, single cell line with pathway readout but no mechanistic detail of how GIPC2 inhibits PI3K/AKT","pmids":["37212125"],"is_preprint":false},{"year":2026,"finding":"GIPC2 directly interacts with pyruvate kinase M2 (PKM2) via its PDZ domain, promoting PKM2 nuclear translocation; nuclear PKM2 then activates SREBP1, driving adipogenic differentiation of mesenchymal stem cells.","method":"Co-immunoprecipitation, PDZ domain interaction assay, nuclear fractionation, SREBP1 reporter assays, knockdown/overexpression in UC-MSCs","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP with domain mapping, nuclear fractionation, and transcription factor activation assay in single lab study","pmids":["41500998"],"is_preprint":false}],"current_model":"GIPC2 is a PDZ-domain scaffolding adaptor protein that, through its PDZ domain, binds multiple partners including Frizzled-7 (activating WNT-β-catenin signaling), PKM2 (promoting its nuclear translocation and SREBP1 activation during adipogenesis), the nuclear protein NONO (co-regulating p27 transcription), and the IGF receptor (coupling to PI3K signaling), while acting as a context-dependent tumor suppressor or oncogene by modulating MAPK/ERK, PI3K/AKT, and WNT pathway outputs."},"narrative":{"teleology":[{"year":2002,"claim":"Identification of GIPC2 as a GIPC1 paralog with a conserved central PDZ domain established it as a candidate PDZ-scaffolding protein likely binding TGFβRIII- or Frizzled-class receptors, framing the key question of what ligands and pathways it engages.","evidence":"cDNA cloning and sequence analysis showing 62% PDZ domain identity to GIPC1","pmids":["11836570"],"confidence":"Low","gaps":["Prediction based solely on sequence homology; no direct binding data for GIPC2 itself","No functional or cellular assay performed","Tissue-level expression pattern not validated at the protein level"]},{"year":2012,"claim":"The first functional role for GIPC2 was established in Xenopus kidney development, where gipc2 depletion caused pronephros defects and its binding to the IGF receptor coupled to PI3K signaling, revealing GIPC2 as a receptor-proximal adaptor linking growth factor input to organ morphogenesis.","evidence":"Morpholino knockdown in Xenopus with pronephros phenotype, rescue by constitutively active PI3K p110*, and Co-IP with IGFR","pmids":["22689378"],"confidence":"Medium","gaps":["Morpholino off-target effects not fully excluded","Rescue by PI3K was partial, leaving other downstream effectors uncharacterized","Whether the mammalian GIPC2-IGFR interaction is conserved was not tested"]},{"year":2021,"claim":"GIPC2 was placed as a tumor-suppressive node upstream of MAPK/ERK-p27 signaling in chromaffin cells: it partners with NONO to co-activate p27 transcription and suppresses ERK and HIF-1α, while oncogenic RET and SDHB mutations reduce GIPC2 expression to drive proliferation, defining its loss-of-function role in pheochromocytoma/paraganglioma pathogenesis.","evidence":"Co-IP of GIPC2–NONO, p27 promoter luciferase assays, genetic epistasis with RET/SDHB mutants in primary rat chromaffin cells and PC12 xenografts","pmids":["33947839"],"confidence":"Medium","gaps":["The direct mechanism by which GIPC2 suppresses ERK phosphorylation is unknown","GIPC2–NONO interaction domain mapping not reported","Nuclear versus cytoplasmic site of GIPC2 action on transcription unclear"]},{"year":2022,"claim":"Direct PDZ-domain–mediated binding of GIPC2 to Frizzled-7 was demonstrated, establishing GIPC2 as an activator of WNT-β-catenin signaling and an oncogenic driver of prostate cancer invasion, contrasting with its tumor-suppressive role in chromaffin cells and showing its context-dependent signaling output.","evidence":"Reciprocal Co-IP with PDZ domain mutagenesis, knockdown/overexpression in vitro and in vivo tumor models","pmids":["35347223"],"confidence":"High","gaps":["Structural basis of the GIPC2 PDZ–Frizzled-7 interaction not resolved","Whether exosomal GIPC2 acts through the same Fzd7-WNT axis in recipient cells is unclear","How GIPC2 switches between tumor-suppressive and oncogenic outputs in different tissues is not mechanistically explained"]},{"year":2023,"claim":"Epigenetic silencing of GIPC2 by promoter CpG methylation in AML was shown, and its forced re-expression induced apoptosis via PI3K/AKT pathway suppression, extending the tumor-suppressive function to hematologic malignancy.","evidence":"Bisulfite sequencing, decitabine-mediated derepression, overexpression in HL-60 cells with phospho-AKT immunoblotting","pmids":["37212125"],"confidence":"Medium","gaps":["Mechanism by which GIPC2 inhibits PI3K/AKT is not identified—no direct target shown","Only a single AML cell line tested","No in vivo validation of anti-leukemic effect"]},{"year":2026,"claim":"GIPC2 was revealed as a metabolic-epigenetic coupling factor: its PDZ domain binds PKM2 and promotes PKM2 nuclear translocation, where PKM2 activates SREBP1 to drive lipogenic gene expression and adipogenic differentiation of mesenchymal stem cells.","evidence":"Co-IP with PDZ domain mapping, nuclear fractionation, SREBP1 reporter assays, knockdown/overexpression in UC-MSCs","pmids":["41500998"],"confidence":"Medium","gaps":["Whether GIPC2 physically escorts PKM2 into the nucleus or merely stabilizes it there is unresolved","Relevance to in vivo adipogenesis or metabolic disease not tested","Single lab study; awaits independent replication"]},{"year":null,"claim":"A unifying mechanism explaining how GIPC2 selectively engages different partners (Fzd7, IGFR, PKM2, NONO) and produces opposing biological outputs (pro-proliferative vs. tumor-suppressive) across tissue contexts remains undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of GIPC2 PDZ domain bound to any partner","No systematic interactome study to define the full partner repertoire","No genetic model (knockout mouse) characterizing organismal phenotype"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,3,5,7]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,7]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,7]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,3,4,5,6]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,4,6]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6]}],"complexes":[],"partners":["FZD7","NONO","PKM2","IGFR"],"other_free_text":[]},"mechanistic_narrative":"GIPC2 is a PDZ-domain scaffolding adaptor that couples transmembrane receptors and cytoplasmic enzymes to downstream signaling cascades in a context-dependent manner. Through its PDZ domain, GIPC2 directly binds Frizzled-7 to activate WNT-β-catenin signaling in prostate cancer cells [PMID:35347223], interacts with the IGF receptor to engage PI3K signaling during kidney morphogenesis [PMID:22689378], and associates with PKM2 to promote its nuclear translocation and subsequent SREBP1-driven adipogenesis [PMID:41500998]. GIPC2 also partners with the nuclear protein NONO to co-regulate p27 transcription and suppresses MAPK/ERK and HIF-1α pathways in chromaffin cells, functioning as a tumor suppressor whose loss downstream of RET and SDHB oncogenic mutations drives pheochromocytoma-associated proliferation [PMID:33947839]. Epigenetic silencing of GIPC2 by promoter methylation occurs in acute myeloid leukemia, where its re-expression induces apoptosis through PI3K/AKT pathway inhibition [PMID:37212125]."},"prefetch_data":{"uniprot":{"accession":"Q8TF65","full_name":"PDZ domain-containing protein GIPC2","aliases":[],"length_aa":315,"mass_kda":34.4,"function":"","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q8TF65/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GIPC2","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GIPC2","total_profiled":1310},"omim":[{"mim_id":"619089","title":"GIPC PDZ DOMAIN-CONTAINING FAMILY, MEMBER 2; GIPC2","url":"https://www.omim.org/entry/619089"},{"mim_id":"608792","title":"GIPC PDZ DOMAIN-CONTAINING FAMILY, MEMBER 3; GIPC3","url":"https://www.omim.org/entry/608792"},{"mim_id":"602912","title":"EUKARYOTIC TRANSLATION INITIATION FACTOR 6; EIF6","url":"https://www.omim.org/entry/602912"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"intestine","ntpm":35.8},{"tissue":"kidney","ntpm":38.7},{"tissue":"lymphoid tissue","ntpm":26.3}],"url":"https://www.proteinatlas.org/search/GIPC2"},"hgnc":{"alias_symbol":["FLJ20075","SEMCAP-2"],"prev_symbol":[]},"alphafold":{"accession":"Q8TF65","domains":[{"cath_id":"2.30.42.10","chopping":"42-197","consensus_level":"medium","plddt":94.854,"start":42,"end":197},{"cath_id":"1.10.150","chopping":"239-312","consensus_level":"high","plddt":89.1031,"start":239,"end":312}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF65","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF65-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF65-F1-predicted_aligned_error_v6.png","plddt_mean":82.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GIPC2","jax_strain_url":"https://www.jax.org/strain/search?query=GIPC2"},"sequence":{"accession":"Q8TF65","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TF65.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TF65/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF65"}},"corpus_meta":[{"pmid":"11836570","id":"PMC_11836570","title":"Molecular cloning and characterization of human GIPC2, a novel gene homologous to human GIPC1 and Xenopus Kermit.","date":"2002","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/11836570","citation_count":71,"is_preprint":false},{"pmid":"11836571","id":"PMC_11836571","title":"Molecular cloning and characterization of human GIPC3, a novel gene homologous to human GIPC1 and GIPC2.","date":"2002","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/11836571","citation_count":68,"is_preprint":false},{"pmid":"12011997","id":"PMC_12011997","title":"Up-regulation of GIPC2 in human gastric cancer.","date":"2002","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/12011997","citation_count":43,"is_preprint":false},{"pmid":"35347223","id":"PMC_35347223","title":"GIPC2 interacts with Fzd7 to promote prostate cancer metastasis by activating WNT signaling.","date":"2022","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/35347223","citation_count":26,"is_preprint":false},{"pmid":"33947839","id":"PMC_33947839","title":"GIPC2 is an endocrine-specific tumor suppressor gene for both sporadic and hereditary tumors of RET- and SDHB-, but not VHL-associated clusters of pheochromocytoma/paraganglioma.","date":"2021","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/33947839","citation_count":11,"is_preprint":false},{"pmid":"22689378","id":"PMC_22689378","title":"Involvement of the eukaryotic initiation factor 6 and kermit2/gipc2 in Xenopus laevis pronephros formation.","date":"2012","source":"The International journal of developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/22689378","citation_count":9,"is_preprint":false},{"pmid":"37212125","id":"PMC_37212125","title":"GIPC2 is a tumor suppressor gene for acute myeloid leukemia and induces apoptosis of leukemia cells by regulating the PI3K/AKT pathway.","date":"2023","source":"Epigenomics","url":"https://pubmed.ncbi.nlm.nih.gov/37212125","citation_count":4,"is_preprint":false},{"pmid":"33280819","id":"PMC_33280819","title":"Depletion of gipc-1 and gipc-2 causes infertility in Caenorhabditis elegans by reducing sperm motility.","date":"2020","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/33280819","citation_count":3,"is_preprint":false},{"pmid":"41500998","id":"PMC_41500998","title":"GIPC2 regulation of the PKM2/SREBP1 signaling axis controls adipogenic differentiation of mesenchymal stem cells.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/41500998","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6241,"output_tokens":1857,"usd":0.023289},"stage2":{"model":"claude-opus-4-6","input_tokens":5145,"output_tokens":2207,"usd":0.12135},"total_usd":0.144639,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"GIPC2 was identified as a novel PDZ-domain protein (315 amino acids) with a central PDZ domain showing 62% amino acid identity to GIPC1, suggesting it may bind TGFβ type III receptor or Frizzled-class WNT receptors analogously to GIPC1/Kermit.\",\n      \"method\": \"Bioinformatics, cDNA cloning, sequence analysis\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational/sequence inference only; no direct binding experiment performed for GIPC2 itself\",\n      \"pmids\": [\"11836570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"GIPC2 directly binds the WNT co-receptor Frizzled-7 (Fzd7) through its PDZ domain, activating WNT-β-catenin signaling cascades and thereby promoting prostate cancer cell adhesion, invasion, and migration.\",\n      \"method\": \"Co-immunoprecipitation, PDZ domain mutagenesis, in vitro and in vivo functional assays (knockdown/overexpression)\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus domain-level mutagenesis plus in vivo tumor model with defined signaling readout\",\n      \"pmids\": [\"35347223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"GIPC2 protein is incorporated into tumor-derived exosomes and exosomal GIPC2 can stimulate prostate cancer cell adhesion, invasion, and migration in recipient cells.\",\n      \"method\": \"Exosome isolation, functional cell-based assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, exosome fractionation plus functional assay but no mechanistic detail of how exosomal GIPC2 acts\",\n      \"pmids\": [\"35347223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"GIPC2 interacts with the nuclear protein NONO, and together they regulate p27 transcription through the same GGCC box on the p27 promoter; GIPC2 also suppresses MAPK/ERK and HIF-1α pathways to inhibit chromaffin cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, promoter reporter/luciferase assays, overexpression in PC12 cells with nude mouse xenograft\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP plus promoter assay plus in vivo tumor model, single lab\",\n      \"pmids\": [\"33947839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In rat adrenal chromaffin cells, RET- and SDHB-associated oncogenic mutations reduce GIPC2 expression to drive ERK activation and p27 downregulation, placing GIPC2 upstream of MAPK/ERK-p27 signaling in pheochromocytoma/paraganglioma pathogenesis; the RET-mutant effect on GIPC2 required dexamethasone (glucocorticoid), while SDHB-mutant effect required its absence.\",\n      \"method\": \"Genetic epistasis in primary rat adrenal chromaffin cells with RET/SDHB mutants, ERK phosphorylation and p27 immunoblotting\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis with defined signaling readout, single lab\",\n      \"pmids\": [\"33947839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In Xenopus (kermit2/gipc2 ortholog), gipc2 depletion causes pronephros reduction and oedema; gipc2 binds the IGF receptor (IGFR) and this interaction is relevant to kidney morphogenesis; partial rescue by constitutively active PI3K p110* implicates GIPC2 in IGF-PI3K signaling during pronephros development.\",\n      \"method\": \"Morpholino knockdown in Xenopus, overexpression rescue with constitutively active PI3K, co-immunoprecipitation with IGFR\",\n      \"journal\": \"The International journal of developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — morpholino KD with clear phenotype and partial pathway rescue; ortholog context\",\n      \"pmids\": [\"22689378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Overexpression of GIPC2 in AML HL-60 cells induces apoptosis by inhibiting the PI3K/AKT pathway; GIPC2 expression is silenced by promoter CpG methylation and restored by decitabine treatment.\",\n      \"method\": \"Overexpression in cell line, western blotting for AKT phosphorylation, bisulfite sequencing, decitabine treatment\",\n      \"journal\": \"Epigenomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, single cell line with pathway readout but no mechanistic detail of how GIPC2 inhibits PI3K/AKT\",\n      \"pmids\": [\"37212125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"GIPC2 directly interacts with pyruvate kinase M2 (PKM2) via its PDZ domain, promoting PKM2 nuclear translocation; nuclear PKM2 then activates SREBP1, driving adipogenic differentiation of mesenchymal stem cells.\",\n      \"method\": \"Co-immunoprecipitation, PDZ domain interaction assay, nuclear fractionation, SREBP1 reporter assays, knockdown/overexpression in UC-MSCs\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with domain mapping, nuclear fractionation, and transcription factor activation assay in single lab study\",\n      \"pmids\": [\"41500998\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GIPC2 is a PDZ-domain scaffolding adaptor protein that, through its PDZ domain, binds multiple partners including Frizzled-7 (activating WNT-β-catenin signaling), PKM2 (promoting its nuclear translocation and SREBP1 activation during adipogenesis), the nuclear protein NONO (co-regulating p27 transcription), and the IGF receptor (coupling to PI3K signaling), while acting as a context-dependent tumor suppressor or oncogene by modulating MAPK/ERK, PI3K/AKT, and WNT pathway outputs.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"GIPC2 is a PDZ-domain scaffolding adaptor that couples transmembrane receptors and cytoplasmic enzymes to downstream signaling cascades in a context-dependent manner. Through its PDZ domain, GIPC2 directly binds Frizzled-7 to activate WNT-β-catenin signaling in prostate cancer cells [PMID:35347223], interacts with the IGF receptor to engage PI3K signaling during kidney morphogenesis [PMID:22689378], and associates with PKM2 to promote its nuclear translocation and subsequent SREBP1-driven adipogenesis [PMID:41500998]. GIPC2 also partners with the nuclear protein NONO to co-regulate p27 transcription and suppresses MAPK/ERK and HIF-1α pathways in chromaffin cells, functioning as a tumor suppressor whose loss downstream of RET and SDHB oncogenic mutations drives pheochromocytoma-associated proliferation [PMID:33947839]. Epigenetic silencing of GIPC2 by promoter methylation occurs in acute myeloid leukemia, where its re-expression induces apoptosis through PI3K/AKT pathway inhibition [PMID:37212125].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of GIPC2 as a GIPC1 paralog with a conserved central PDZ domain established it as a candidate PDZ-scaffolding protein likely binding TGFβRIII- or Frizzled-class receptors, framing the key question of what ligands and pathways it engages.\",\n      \"evidence\": \"cDNA cloning and sequence analysis showing 62% PDZ domain identity to GIPC1\",\n      \"pmids\": [\"11836570\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Prediction based solely on sequence homology; no direct binding data for GIPC2 itself\",\n        \"No functional or cellular assay performed\",\n        \"Tissue-level expression pattern not validated at the protein level\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The first functional role for GIPC2 was established in Xenopus kidney development, where gipc2 depletion caused pronephros defects and its binding to the IGF receptor coupled to PI3K signaling, revealing GIPC2 as a receptor-proximal adaptor linking growth factor input to organ morphogenesis.\",\n      \"evidence\": \"Morpholino knockdown in Xenopus with pronephros phenotype, rescue by constitutively active PI3K p110*, and Co-IP with IGFR\",\n      \"pmids\": [\"22689378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Morpholino off-target effects not fully excluded\",\n        \"Rescue by PI3K was partial, leaving other downstream effectors uncharacterized\",\n        \"Whether the mammalian GIPC2-IGFR interaction is conserved was not tested\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"GIPC2 was placed as a tumor-suppressive node upstream of MAPK/ERK-p27 signaling in chromaffin cells: it partners with NONO to co-activate p27 transcription and suppresses ERK and HIF-1α, while oncogenic RET and SDHB mutations reduce GIPC2 expression to drive proliferation, defining its loss-of-function role in pheochromocytoma/paraganglioma pathogenesis.\",\n      \"evidence\": \"Co-IP of GIPC2–NONO, p27 promoter luciferase assays, genetic epistasis with RET/SDHB mutants in primary rat chromaffin cells and PC12 xenografts\",\n      \"pmids\": [\"33947839\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The direct mechanism by which GIPC2 suppresses ERK phosphorylation is unknown\",\n        \"GIPC2–NONO interaction domain mapping not reported\",\n        \"Nuclear versus cytoplasmic site of GIPC2 action on transcription unclear\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Direct PDZ-domain–mediated binding of GIPC2 to Frizzled-7 was demonstrated, establishing GIPC2 as an activator of WNT-β-catenin signaling and an oncogenic driver of prostate cancer invasion, contrasting with its tumor-suppressive role in chromaffin cells and showing its context-dependent signaling output.\",\n      \"evidence\": \"Reciprocal Co-IP with PDZ domain mutagenesis, knockdown/overexpression in vitro and in vivo tumor models\",\n      \"pmids\": [\"35347223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of the GIPC2 PDZ–Frizzled-7 interaction not resolved\",\n        \"Whether exosomal GIPC2 acts through the same Fzd7-WNT axis in recipient cells is unclear\",\n        \"How GIPC2 switches between tumor-suppressive and oncogenic outputs in different tissues is not mechanistically explained\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Epigenetic silencing of GIPC2 by promoter CpG methylation in AML was shown, and its forced re-expression induced apoptosis via PI3K/AKT pathway suppression, extending the tumor-suppressive function to hematologic malignancy.\",\n      \"evidence\": \"Bisulfite sequencing, decitabine-mediated derepression, overexpression in HL-60 cells with phospho-AKT immunoblotting\",\n      \"pmids\": [\"37212125\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which GIPC2 inhibits PI3K/AKT is not identified—no direct target shown\",\n        \"Only a single AML cell line tested\",\n        \"No in vivo validation of anti-leukemic effect\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"GIPC2 was revealed as a metabolic-epigenetic coupling factor: its PDZ domain binds PKM2 and promotes PKM2 nuclear translocation, where PKM2 activates SREBP1 to drive lipogenic gene expression and adipogenic differentiation of mesenchymal stem cells.\",\n      \"evidence\": \"Co-IP with PDZ domain mapping, nuclear fractionation, SREBP1 reporter assays, knockdown/overexpression in UC-MSCs\",\n      \"pmids\": [\"41500998\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether GIPC2 physically escorts PKM2 into the nucleus or merely stabilizes it there is unresolved\",\n        \"Relevance to in vivo adipogenesis or metabolic disease not tested\",\n        \"Single lab study; awaits independent replication\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unifying mechanism explaining how GIPC2 selectively engages different partners (Fzd7, IGFR, PKM2, NONO) and produces opposing biological outputs (pro-proliferative vs. tumor-suppressive) across tissue contexts remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of GIPC2 PDZ domain bound to any partner\",\n        \"No systematic interactome study to define the full partner repertoire\",\n        \"No genetic model (knockout mouse) characterizing organismal phenotype\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 3, 5, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 7]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 3, 4, 5, 6]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 4, 6]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"FZD7\",\n      \"NONO\",\n      \"PKM2\",\n      \"IGFR\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}