TFAP2C (AP-2 gamma, Q92754) — curation notes

Project: NEURAL_CREST_ORIGINS, Tier 4 (missing module members). Review date 2026-10-08.

Identity and molecular activity

• AP-2 family sequence-specific TF; binds GCC(N3)GGC as homo- or heterodimer via the basic region + helix-span-helix; N-terminal PY/Pro-rich transactivation domain. Originally purified as ERF-1 from MCF-7 cells, binding the ESR1 promoter [PMID:9113991 "This cDNA encodes a protein of 48 kDa previously identified as the AP2gamma transcription factor"; "ERF-1 activates ER gene transcription by binding to the imperfect palindrome CCCTGCGGGG within the promoter of the ER gene"].
• Activator and promoter-specific repressor: AP-2gamma represses Mn-SOD (SOD2) [PMID:11278550 "AP-2alpha and AP-2gamma were more active in this regard than AP-2beta"; "Repression of Mn-SOD by AP-2 was dependent on DNA binding"] while activating c-erbB-3 in the same assay ["another AP-2-responsive gene, c-erbB-3, was transactivated by AP-2"].
• Genome-wide in MCF-7: ChIP-seq motif SCCTSRGGS; primary targets both induced and repressed PMID:20629094.
• Cofactors: CITED2 coactivates all AP-2 isoforms and binds the TFAP2C dimerization domain [PMID:11694877 "CITED2 interacts with and co-activates all isoforms of transcription factor AP-2 (TFAP2)"; PMID:12586840 "CITED2 interacted with the dimerization domain of TFAP2C"]. CITED2 with TFAP2C transactivates PITX2C PMID:22735262. KCTD1 represses all three major AP-2s PMID:19115315. SUMOylation via UBC9 dampens activity PMID:12072434. MTA1/NuRD complex on the ESR1 promoter [PMID:24413532 "the transcription factor AP-2γ (TFAP2C) and the IFN-γ-inducible protein 16 (IFI16) were components of the complex"; "in MCF7, TFAP2C activated the reporter encoding ERpro315"]. WWOX retains TFAP2C in the cytosol (Reactome R-HSA-8864569).

Developmental roles (synthesis)

1. Trophectoderm / placenta (core, conserved in mammals). Mouse Tfap2c null dies ~E7.5 from extra-embryonic failure PMID:26811378. In totipotent mouse embryos it binds/activates early TE and ICM genes, then late TE genes with CDX2 PMID:38243114. Human TSC to EVT: early-stage TF that pre-occupies EVT genes PMID:38346993. Mouse Tfap2c carries GO:0001829 trophectodermal cell differentiation by IMP (QuickGO, PMID:20404091, PMID:38243114); human TFAP2C does not -> NEW GO:0001829 (ISS).
2. Primordial germ cells (core). Human: TFAP2C-null hESCs cannot make hPGCLCs; TFAP2C acts upstream of PRDM1 to induce SOX17 and blocks somatic fates [PMID:31875561 "TFAP2C functions in the TFAP2A+ progenitors upstream of PRDM1 to regulate the expression of SOX17"; "This serves to protect hPGCLCs from crossing the Weismann's barrier to adopt somatic cell fates"]; binds the OCT4 naive enhancer PMID:30590035; GATA3/2 + SOX17 + TFAP2C suffice to induce hPGCLCs PMID:33608411. Mouse: PGCs specified but lost by E8.0 in Tfap2c mutants PMID:19776388. Comparator: mouse Prdm1 carries GO:0007281 germ cell development (IGI); mouse Tfap2c carries GO:0030718 (IMP); human PRDM1/SOX17 do not (QuickGO 2026-10-08) -> NEW GO:0007281 (IMP, human data).
3. Epidermis / mammary / cortex (non-core, mostly redundant with TFAP2A). Mouse Tfap2a/Tfap2c double epidermal knockout PMID:18824566; cortical basal progenitors PMID:19749747. Not added as NEW; noted in questions.
4. Breast cancer. ESR1/FOXA1/RET regulation PMID:20629094; luminal identity PMID:24835590. Disease context, captured by MF terms only.

Neural crest: network layer

• Chick (Rothstein & Simoes-Costa 2020, full text): TFAP2C is at the border during gastrula, then lost from crest and restricted to epidermis PMID:31848212. Knockdown lowers border genes only PMID:31848212. CUT&RUN: 5863 of 7021 TFAP2C peaks co-occupied with TFAP2A at HH6; co-IP of TFAP2A with TFAP2C in embryo. TFAP2A/C peaks in the TFAP2B locus (feed-forward), and TFAP2B represses TFAP2C cell-autonomously PMID:31848212. TFAP2C cannot substitute for TFAP2B in specification PMID:31848212.
• Zebrafish (Li & Cornell 2007, full text): tfap2c alone has no visible phenotype; tfap2a+tfap2c together abolish crest induction, cell-autonomously, during gastrula [PMID:17258188 "simultaneous inhibition of tfap2a and tfap2c utterly prevents neural crest induction"; "Because tfap2c expression is rapidly down regulated in neural crest, Tfap2a/c function in neural crest induction must occur during gastrula stage."]. Border markers pax3/msxb/zic2b were normal in the double, placing Tfap2a/c "in parallel to or possibly downstream of Pax3, Zic2b, and Msxb, and upstream of Foxd3, Sox9, Sox10, and Snai1b".
• Synthesis. The two species disagree on exact epistasis relative to the other border genes (chick: upstream of MSX1/PAX7/ZIC1/GBX2; zebrafish: parallel/downstream of pax3/msxb/zic2b) but agree on what matters for GO: TFAP2C acts only at gastrula/border-induction stage, is gone from the crest before specification, is redundant with TFAP2A, and does not drive specification itself. That is the border layer, so GO:0014029 neural crest formation (the term defined as forming the ectodermal border region), not GO:0014034 or GO:0014036. TFAP2C is a DNA-binding TF co-occupying border enhancers with TFAP2A, so it passes the participation test (it does part of the work). Human evidence is absent (no human border model), so evidence code ISS from chick/zebrafish orthologs, matching TFAP2A.
• Comparator check (QuickGO, 2026-10-08, NC branch GO:0014029/14030/14031/14032/14033/14034/14036/0001755 with descendants, taxa 9606, 10090, 10116, 9031, 8355, 8364, 7955): zebrafish tfap2c (Q5PQZ4 and TrEMBL isoforms) carries GO:0014032 IGI (PMID:17258188, PMID:17724731, PMID:22241841) and GO:0014036 IGI (PMID:20885782); zebrafish tfap2a carries GO:0014032 IGI and GO:0014036 IMP/IGI; mouse Tfap2a GO:0014032 IMP (PMID:8622766), rat Tfap2a ISO. No TFAP2B, TFAP2C, TFAP2D or TFAP2E in human, mouse, rat, chicken or Xenopus carries any NC term; mouse Tfap2c (Q61312) has none (its null dies before crest forms). So the absence on human TFAP2C is a coverage gap, not a convention; the zebrafish ortholog's terms show GO accepts TFAP2C in crest processes. The zebrafish GO:0014036 is from a double knockdown (IGI), consistent with redundancy; the chick data argue that TFAP2C itself does not act at the specification step, so GO:0014036 is not transferred.
• Module placement. Border specification part, as the TFAP2A partner: TFAP2A–TFAP2C heterodimer annoton (GO:0001228, GO:0014029). Edges: TFAP2A/C -> TFAP2B (activation, CUT&RUN peaks in TFAP2B locus); TFAP2B -| TFAP2C (repression, cell-autonomous, likely direct). TFAP2C should not enter the specification part.

Evolution

• Amphioxus has a single AP-2 expressed in non-neural ectoderm only (TFAP2A review, PMID:12397104), so AP-2's border role is a vertebrate co-option. Rothstein & Simoes-Costa note TFAP2C/TFAP2B expression lies within TFAP2A's domain, "suggesting subfunctionalization of these paralogs over the course of evolution" PMID:31848212. TFAP2C kept the ancestral non-neural-ectoderm/epidermis expression and took on the gastrula border-induction share; TFAP2B took the crest-specification share. Mammals additionally use TFAP2C in trophectoderm and germline (placental mammal-specific deployments).

GOA row decisions (60 rows)

• Protein binding: CITED2 rows (PMID:11694877, PMID:12586840 x2) -> MODIFY GO:0001223; KCTD1 (PMID:19115315) -> MODIFY GO:0001222 (consistent with TFAP2A); MTA1 (PMID:24413532) -> MODIFY GO:0001221 transcription coregulator binding (MTA1/NuRD role is context-dependent; sign not assignable); UBC9 x2 -> REMOVE (substrate of SUMOylation). No AP-2 clathrin adaptor confusion found in these abstracts (all are transcription factor AP-2 papers).
• cell-cell signaling TAS (PMID:9113991) -> REMOVE (the paper identifies ERF-1 as AP-2gamma; nothing on intercellular signalling).
• male gonad development IEP (PMID:17848411) -> MARK_AS_OVER_ANNOTATED (germ cell transcript measurement only; the real role is germ cell development, added NEW).
• negative regulation of gene expression, epigenetic IMP (PMID:24413532) -> UNDECIDED (abstract says TFAP2C activated ESR1 in MCF7; the epigenetic repression is attributed to MTA1/IFI16/HDAC; full text unavailable).
• ICM differentiation / morula formation (mouse-derived) -> KEEP_AS_NON_CORE (mouse 8-cell 'bipotency activation'; human preimplantation evidence lacking).
• cytosol TAS x2 -> KEEP_AS_NON_CORE (WWOX-mediated cytoplasmic retention is a regulatory state).