Regulation of Nucleotide Metabolism and Germline Proliferation in Response to Nucleotide Imbalance and Genotoxic Stresses by EndoU Nuclease.

Nucleotide deprivation and imbalance present detrimental conditions for animals and are thus expected to trigger cellular responses that direct protective changes in metabolic, developmental, and behavioral programs, albeit such mechanisms are vastly underexplored. Following our previous finding that Caenorhabditis elegans shut down germ cell proliferation in response to pyrimidine deprivation, we find in this study that endonuclease ENDU-2 regulates nucleotide metabolism and germ cell proliferation in response to nucleotide imbalance and other genotoxic stress, and that it affects mitotic chromosomal segregation in the intestine and lifespan. ENDU-2 expression is induced by nucleotide imbalance and genotoxic stress, and ENDU-2 exerts its function in the intestine, mostly by inhibiting the phosphorylation of CTPS-1 through repressing the PKA pathway and histone deacetylase HDA-1. Human EndoU also affects the response to genotoxic drugs. Our work reveals an unknown role of ENDU-2 in regulating nucleotide metabolism and animals' response to genotoxic stress, which may link EndoU function to cancer treatment.