Abstract: |
The Mre11 complex (consisting of MRE11, RAD50, and NBS1/Xrs2) is required for double-strand break (DSB) formation, processing, and checkpoint signaling during meiotic cell division in S. cerevisiae [1-8]. Whereas studies of Mre11 complex mutants in S. pombe and A. thaliana indicate that the complex has other essential meiotic roles [9-11], relatively little is known regarding the functions of the complex downstream of meiotic break formation and processing or its role in meiosis in higher eukaryotes. We analyzed meiotic events in mice harboring hypomorphic Mre11 and Nbs1 mutations which, unlike null mutants, support viability [12-16]. Our studies revealed defects in the temporal progression of meiotic prophase, incomplete and aberrant synapsis of homologous chromosomes, persistence of strand exchange proteins, and alterations in both the frequency and placement of MLH1 foci, a marker of crossovers. A unique sex-dependent effect on MLH1 foci and chiasmata numbers was observed: males exhibited an increase and females a decrease in recombination levels. Thus, our findings implicate the Mre11 complex in meiotic DNA repair and synapsis in mammals and indicate that the complex may contribute to the establishment of normal sex-specific differences in meiosis. © 2007 Elsevier Ltd. All rights reserved. |
Keywords: |
immunohistochemistry; unclassified drug; dna binding protein; genetics; mutation; dna-binding proteins; comparative study; cell cycle protein; mouse; animal; meiosis; metabolism; mouse mutant; mammalia; animals; cell cycle proteins; mice; atp-binding cassette transporters; mus; dna repair; nuclear protein; mice, mutant strains; physiology; nuclear proteins; dna; saccharomyces cerevisiae; eukaryota; abc transporter; murinae; dna repair enzymes; fluorescence microscopy; microscopy, fluorescence; multiprotein complexes; sex difference; sex factors; polydeoxyribonucleotide synthase; chromosome analysis; chromosome pairing; synapsis; cytogenetic analysis; schizosaccharomyces pombe; crossing over; crossing over, genetic; multiprotein complex; mre11a protein, mouse; nijmegen breakage syndrome 1 protein, mouse; arabidopsis thaliana; rad50 protein, mouse
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