The Mre11 complex influences DNA repair, synapsis, and crossing over in murine meiosis.
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. Whereas studies of Mre11 complex mutants in S. pombe and A. thaliana indicate that the complex has other essential meiotic roles , 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 . 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.
Cherry
Sheila M
SM
Department of Genetics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Adelman
Carrie A
CA
Theunissen
Jan W
JW
Hassold
Terry J
TJ
Hunt
Patricia A
PA
Petrini
John H J
JH
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D017766:Acid Anhydride Hydrolases; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D023902:Chromosome Pairing / Q000235:genetics / Q000502:physiology*; D003434:Crossing Over, Genetic / Q000235:genetics / Q000502:physiology*; D020732:Cytogenetic Analysis; D004260:DNA Repair / Q000235:genetics / Q000502:physiology*; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D000076228:MRE11 Homologue Protein; D008297:Male; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012737:Sex Factors
D018528:ATP-Binding Cassette Transporters; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C512689:Mre11a protein, mouse; D046912:Multiprotein Complexes; C466108:Nijmegen breakage syndrome 1 protein, mouse; D009687:Nuclear Proteins; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C495198:Rad50 protein, mouse; D045643:DNA Repair Enzymes