A novel mouse allele of the DNA/RNA helicase senataxin (Setxspcar3) causing meiotic arrest of spermatocytes and male infertility

Abstract

ABSTRACTAn unbiased screen for discovering novel genes for fertility identified thespcar3, spermatocyte arrest 3,mutant phenotype. Thespcar3mutation identified a new allele of theSetxgene, encoding senataxin, a DNA/RNA helicase that regulates transcription termination by resolving DNA/RNA hybrid R-loop structures. Although mutations in the humanSETXgene cause neural disorders,Setxspcar3mutant mice do not show any apparent neural phenotype, but instead exhibit male infertility and female subfertility. Histology of theSetxspcar3mutant testes revealed absence of spermatids and mature spermatozoa in the seminiferous tubules. Cytological analysis of chromosome spread preparations of theSetxspcar3mutant spermatocytes revealed normal synapsis, but aberrant DNA damage in the autosomes, and defective formation of the sex body. Furthermore,Setxspcar3testicular cells exhibited abnormal accumulation of R-loops compared to wild type testicular cells. Transient expression assays identified regions of the senataxin protein required for sub-nuclear localization. Together, these results not only confirm that senataxin is required for normal meiosis and spermatogenesis but also provide a new resource for determination of its role in maintaining R-loop formation and genome integrity.