Functional genetic networks that maintain genomic stability in mammalian cell lines and in Caenorhabditis elegans

The spontaneous formation of lesions in DNA is among the most significant threats to genomic integrity. We are using genetic and biochemical methods in the model organism Caenorhabditis elegans (C.elegans) and DNA repair deficient mouse cell lines to stud y the biological consequences of accumulation of endogenous DNA damage on cell physiology and genomic stability. Furthermore, we study whether endogenously formed base damage and base analogues are able to activate downstream DNA damage response (DDR) pat hways and, if so, to characterise the molecular players involved. The ability to respond correctly to spontaneous DNA damage is crucial for survival of an organism and to prevent mutations and development of disease. DNA damage response mechanisms consist of cellular processes that coordinate and execute responses to DNA damage and include activation of DNA repair, of cell-cycle arrest and cell death by apoptosis. We are interested to study whether DNA repair enzymes, with their unique ability to recognis e subtly altered DNA bases amongst a vast excess of normal DNA, may function as DNA damage sensor proteins and to elucidate how different DNA repair and DNA damage tolerance pathways work together to maintain genomic stability. Studying cellular responses to spontaneous lesions presents a technical challenge in how to introduce enough lesions in order to activate and study downstream effects. We circumvent this problem by modifying the nucleotide precursor pools by RNA interference (RNAi) technology in C. elegans, thus introducing damaged or altered bases into DNA upon DNA replication. In this way, we believe that C.elegans may contribute to bridge the gap of knowledge of genetic interaction networks for the protection against endogenous DNA damage between unicellular systems and animals, particularly by offering the possibility of identifying genetic interactions between the DNA repair and the apoptotic machinery.