Modulation of RAD51 activity by the c-Met receptor tyrosine kinase in the repair of DNA double-strand breaks

Genomic instability due to deregulation of DNA repair pathways may be at the onset of cancer and subsequently lead to resistance to chemotherapy and radiotherapy. Understanding these biological mechanisms is therefore essential in the fight against cancer. RAD51 is the core protein of the homologous recombinant double-stranded DNA repair pathway. This repair leads to faithful DNA repair. The recombinase activity of the RAD51 protein is finely regulated by post-translational modifications such as phosphorylation. Over the last decade, more and more studies have suggested the existence of a relationship between receptors with tyrosine kinase activity, which are often overactivated and involved in aggressiveness and cancer proliferation; and DNA repair. Among these receptors with tyrosine kinase activity, the c-Met/HGF-SF duo is often mutated, over-expressed or constitutively activated in many cancers and its inhibition has been shown to induce a decrease in repair by homologous recombination. Through this thesis, we show for the first time that c-Met is able to phosphorylate the RAD51 protein on four tyrosine residues located mainly in the human recombinase nucleofilament monomer- monomer interface. We show the implication of these phosphorylations on the activity of RAD51 in the different steps of homologous recombination. All the results obtained suggest the possible role of these modifications in the regulation of RAD51 and underline the importance of c-Met in the response to DNA damage. (author)