Bases moléculaires des syndromes de déficiences en transcription et réparation de l'ADN

Xeroderma pigmentosum, le syndrome de Cockayne et la trichothiodystrophie sont des maladies rares, autosomales et récessives. Ces syndromes sont causés par des mutations dans les gènes codant pour des protéines impliquées dans la transcription et dans la réparation de l'ADN par excision de nucléotides. Le but de ma thèse de mieux comprendre les mécanismes moléculaires à l'origine de ces pathologies. Mes résultats ont permis de montrer un rôle pour le complexe TFIIH et la protéine XPG dans la biogénèse des ribosomes : TFIIH serait un facteur de transcription jouant un rôle, avec l'ARN polymerase I, dans l'élongation des ARNs ribosomiques et XPG aurait un rôle dans la maturation de ces derniers. Enfin, nous avons utilisé le système tripartite split-GFP, pour étudier, in vivo les interactions protéines - protéines au sein du complexe protéique TFIIH.Xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy are rare autosomal recessive disorders caused by mutations in proteins which are implicated in nucleotide excision repair and transcription. In this thesis, we examined different cellular aspects to better understand the molecular mechanisms underlying the pathophysiology of these severe diseases. First, we describe the role of TFIIH and XPG in ribosome biogenesis: we characterized the function of TFIIH as a RNA polymerase I transcription factor functioning in elongation and described a novel role for XPG during early ribosomal RNA maturation. Next, we examined the DNA repair pathway responsible for repair of the transcribed ribosomal RNA. Finally, we used a novel in vivo tripartite split-GFP system to investigate protein-protein interactions within TFIIH

DNA damage-inducing anticancer therapies: From global to precision damage

DNA damage-inducing therapies are of tremendous value for cancer treatment and function by the direct or indirect formation of DNA lesions and subsequent inhibition of cellular proliferation. Of central importance in the cellular response to therapy-induced DNA damage is the DNA damage response (DDR), a protein network guiding both DNA damage repair and the induction of cancer-e

Mutations in TFIIH causing trichothiodystrophy are responsible for defects in ribosomal RNA production and processing

The basal transcription/repair factor II H (TFIIH), found mutated in cancer-prone or premature aging diseases, plays a still unclear role in RNA polymerase I transcription. Furthermore, the impact of this function on TFIIHrelated diseases, such as trichothiodystrophy (TTD), remains to be explored. Here, we studied the involvement of TFIIH during the whole process of ribosome biogenesis, from RNAP1 transcription to maturation steps of the ribosomal RNAs. Our results show that TFIIH is recruited to the ribosomal DNA in an active transcription- dependent manner and functions in RNAP1 transcription elongation through ATP hydrolysis of the XPB subunit. Remarkably, we found a TFIIH allele-specific effect, affecting RNAP1 transcription and/or the pre-rRNA maturation process. Interestingly, this effect was observed in mutant TFIIH-TTD cells and also in the brains of TFIIH-TTD mice. Our findings provide evidence that defective ribosome synthesis represents a new faulty mechanism involved in the pathophysiology of TFIIH-related diseases.</p