TFIIH Subunit Alterations Causing Xeroderma Pigmentosum and Trichothiodystrophy Specifically Disturb Several Steps during Transcription

Abstract

Mutations in genes encoding the ERCC3 (XPB), ERCC2 (XPD), and GTF2H5 (p8 or TTD-A) subunits of the transcription and DNA-repair factor TFIIH lead to three autosomal-recessive disorders: xeroderma pigmentosum (XP), XP associated with Cockayne syndrome (XP/CS), and trichothiodystrophy (TTD). Although these diseases were originally associated with defects in DNA repair, transcription deficiencies might be also implicated. By using retinoic acid receptor beta isoform 2 (RARB2) as a model in several cells bearing mutations in genes encoding TFIIH subunits, we observed that (1) the recruitment of the TFIIH complex was altered at the activated RARB2 promoter, (2) TFIIH participated in the recruitment of nucleotide excision repair (NER) factors during transcription in a manner different from that observed during NER, and (3) the different TFIIH variants disturbed transcription by having distinct consequences on post-translational modifications of histones, DNA-break induction, DNA demethylation, and gene-loop formation. The transition from heterochromatin to euchromatin was disrupted depending on the variant, illustrating the fact that TFIIH, by contributing to NER factor recruitment, orchestrates chromatin remodeling. The subtle transcriptional differences found between various TFIIH variants thus participate in the phenotypic variability observed among XP, XP/CS, and TTD individuals.

Nucleotide Excision Repair and Transcriptional Regulation: TFIIH and Beyond

“…In this context, it has been shown that Dmp52, the Drosophila homolog of the p52 subunit of TFIIH, interacts with Dmp18, the homolog of Swc6/p18, a subunit of the SWR1/SRCAP complex responsible for H2AZ exchange in fungi and vertebrates (84). TFIIH might also disturb histone posttranslational modifications (PTMs) that normally occur on activated promoters (85). However, little is known about how TFIIH influences histone PTMs as well as other key steps for accurate RNA synthesis, such as DNA breaks, DNA demethylation, and gene loop formation.…”

“…Because TFIIH is in a large protein network, the cause of certain clinical features could also result from dysfunction in at least one of the many factors that participate in the transcription initiation process. Examples include the consequences of TFIIH mutations on the recruitment of transcription factors and on chromatin remodeling at the promoters of activated genes (85,86). Strikingly, the transcriptional defects differ according to the nature and the combination of the TFIIH mutations found in the patients (145,146).…”

Specific Inhibition of HIV Infection by the Action of Spironolactone in T Cells

“…Does SP inhibit initiation and elongation of transcription through XPB degradation? SP could also inhibit other TFIIH actions, such as posttranslational modifications of histones, DNA demethylation, or chromatin remodeling (27).…”

Lurbinectedin Specifically Triggers the Degradation of Phosphorylated RNA Polymerase II and the Formation of DNA Breaks in Cancer Cells

“…Chromatin was isolated and sonicated (23). Samples were immunoprecipitated (IP) with antibodies at 4 C overnight, and protein G-Sepharose beads (Upstate) were added, incubated 3 hours at 4 C, and sequentially washed.…”

“…DNA fragments were purified using the QIAquick PCR purification Kit (QIAGEN) and analyzed by real-time PCR using sets of primers targeting RARb2 gene promoter: fw 5'-TGGTGATGTCAGAC-TAGTTGGGTC-3' and rev 5'-GCTCACTTCCTACTACTTCTGT-CAC-3'; and RARb2 exon 4: fw 5'-TCCAGCTGTCAGGAATGA-CAGGAA-3' and rev 5'-TGAGATCGTCCAACTCAGCTGTCA-3'. Biotin-ChIP assays have been performed as previously described (23).…”