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J Biol Chem. 2018 Sep 28;293(39):14974-14988. doi: 10.1074/jbc.RA118.003444. Epub 2018 Aug 1.

Small molecule-based targeting of TTD-A dimerization to control TFIIH transcriptional activity represents a potential strategy for anticancer therapy.

Author information

1
From the Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, BP-64182, F-31077 Toulouse, France, virginie.gervais@ipbs.fr.
2
From the Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, BP-64182, F-31077 Toulouse, France.
3
the Université Claude Bernard Lyon 1, INSERM U1217, Institut NeuroMyoGène, CNRS UMR 5310, F-69008 Lyon, France, and.
4
the Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center of Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan.
5
the Université Claude Bernard Lyon 1, INSERM U1217, Institut NeuroMyoGène, CNRS UMR 5310, F-69008 Lyon, France, and ambra.mari@univ-lyon1.fr.

Abstract

The human transcription factor TFIIH is a large complex composed of 10 subunits that form an intricate network of protein-protein interactions critical for regulating its transcriptional and DNA repair activities. The trichothiodystrophy group A protein (TTD-A or p8) is the smallest TFIIH subunit, shuttling between a free and a TFIIH-bound state. Its dimerization properties allow it to shift from a homodimeric state, in the absence of a functional partner, to a heterodimeric structure, enabling dynamic binding to TFIIH. Recruitment of p8 at TFIIH stabilizes the overall architecture of the complex, whereas p8's absence reduces its cellular steady-state concentration and consequently decreases basal transcription, highlighting that p8 dimerization may be an attractive target for down-regulating transcription in cancer cells. Here, using a combination of molecular dynamics simulations to study p8 conformational stability and a >3000-member library of chemical fragments, we identified small-molecule compounds that bind to the dimerization interface of p8 and provoke its destabilization, as assessed by biophysical studies. Using quantitative imaging of TFIIH in living mouse cells, we found that these molecules reduce the intracellular concentration of TFIIH and its transcriptional activity to levels similar to that observed in individuals with trichothiodystrophy owing to mutated TTD-A Our results provide a proof of concept of fragment-based drug discovery, demonstrating the utility of small molecules for targeting p8 dimerization to modulate the transcriptional machinery, an approach that may help inform further development in anticancer therapies.

KEYWORDS:

DNA transcription; GTF2H5; STD-NMR; TFIIH; cancer; drug screening; nuclear magnetic resonance (NMR); protein-protein interaction; quantitative imaging; transcriptional regulation

PMID:
30068551
PMCID:
PMC6166727
[Available on 2019-09-28]
DOI:
10.1074/jbc.RA118.003444
[Indexed for MEDLINE]

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