Mouse MutS-like protein Msh5 is required for proper chromosome synapsis inmale and female meiosis

Members of the mammalian mismatch repair protein family of MutS and MutL ho mologs have been implicated in postreplicative mismatch correction and chro mosome interactions during meiotic recombination. Here we demonstrate that mice carrying a disruption in Mut5 homolog Msh5 show a meiotic defect, lead ing to male and female sterility. Histological and cytological examination of prophase I stages in both sexes revealed an extended zygotene stage, cha racterized by impaired and aberrant chromosome synapsis, that was followed by apoptotic cell death. Thus, murine Msh5 promotes synapsis of homologous chromosomes in meiotic prophase I.