GTF2H1

GTF2H1 encodes the 62-kDa core subunit of the transcription factor IIH (TFIIH) complex, which functions in both RNA polymerase II-dependent transcription and nucleotide excision repair (NER) (PMID:30287812, PMID:7789978). GTF2H1 levels set TFIIH stability and function: depletion of the SWI/SNF ATPases BRM/SMARCA2 or BRG1/SMARCA4 downregulates GTF2H1, compromising TFIIH integrity and rendering SWI/SNF-deficient cells sensitive to UV irradiation and cisplatin in a GTF2H1-dependent manner (PMID:30287812). In the melanocytic lineage, MITF directly transactivates GTF2H1, and MITF loss collapses GTF2H1-dependent TFIIH with consequent proteasomal degradation of the CDK7-containing CAK subcomplex, defining a MITF→GTF2H1→TFIIH-CAK axis that governs general transcription and UV-induced NER (PMID:30651597). Consistent with its NER role, GTF2H1 protein is induced in hepatic cells responding to AZT-induced DNA damage downstream of the recognition factor XPC (PMID:21192964).

1. 1995 Medium

   Establishing the molecular identity and genomic position of the gene was the first step, fixing GTF2H1 as the 62-kDa TFIIH subunit and assigning it a chromosomal locus.

   Evidence FISH on banded chromosomes with YAC/cosmid physical mapping

   PMID:7789978

   Open questions at the time

   • No functional perturbation linking the locus to TFIIH activity
   • Provides identity/position but not mechanism in transcription or repair
2. 2010 Medium

   Whether GTF2H1-containing TFIIH participates in the cellular response to a specific DNA-damaging agent was addressed by showing GTF2H1 induction and XPC-dependent NER engagement upon AZT treatment.

   Evidence PCR array, Western blot, and shRNA knockdown of XPC with viability/apoptosis assays in HepG2 hepatoma cells

   PMID:21192964

   Open questions at the time

   • Pathway placement inferred from XPC epistasis; no GTF2H1-specific perturbation performed
   • Does not establish whether GTF2H1 induction is functionally required for AZT resistance
3. 2013 Low

   Whether GTF2H1 induction by AZT extends beyond cancer cells was tested by measuring dose-dependent upregulation in non-transformed hepatic cells.

   Evidence PCR array and Western blot across AZT dose range in immortalized THLE2 cells

   PMID:23675285

   Open questions at the time

   • Single-method protein measurement with no GTF2H1-specific functional perturbation
   • Corroborative only; adds little new mechanism beyond the prior HepG2 finding
4. 2018 High

   The question of what maintains GTF2H1 expression and how its level controls TFIIH function was answered by showing SWI/SNF ATPases promote GTF2H1 transcription and that GTF2H1 abundance dictates TFIIH stability and DNA-damage sensitivity.

   Evidence RNAi depletion of BRM/BRG1, TFIIH stability and GTF2H1 expression measurement, UV and cisplatin sensitivity assays in SWI/SNF-deficient cancer cells

   PMID:30287812

   Open questions at the time

   • Direct versus indirect transcriptional control of GTF2H1 by SWI/SNF not fully resolved
   • Whether the same dependency holds across non-cancer cell types untested
5. 2019 High

   Lineage-specific control of GTF2H1 was established by demonstrating MITF directly transactivates it, defining a regulatory axis in which GTF2H1 loss destabilizes the TFIIH-CAK subcomplex.

   Evidence ChIP, transactivation/reporter assays, and MITF depletion with CDK7 stability, NER, and transcription readouts in melanoma cells and in vivo

   PMID:30651597

   Open questions at the time

   • Generality of MITF control beyond the melanocytic lineage unknown
   • Mechanism of CDK7 degradation upon GTF2H1 loss not structurally defined

• The structural basis by which GTF2H1/p62 organizes TFIIH and coordinates the transcription versus NER functions of the complex remains uncharacterized in this corpus.
• No structural or biochemical reconstitution of p62 within TFIIH in the timeline
• Direct enzymatic or scaffolding contribution of GTF2H1 to NER not dissected