Rec8-containing cohesin maintains bivalents without turnover during the growing phase of mouse oocytes.
During female meiosis, bivalent chromosomes are thought to be held together from birth until ovulation by sister chromatid cohesion mediated by cohesin complexes whose ring structure depends on kleisin subunits, either Rec8 or Scc1. Because cohesion is established at DNA replication in the embryo, its maintenance for such a long time may require cohesin turnover. To address whether Rec8- or Scc1-containing cohesin holds bivalents together and whether it turns over, we created mice whose kleisin subunits can be cleaved by TEV protease. We show by microinjection experiments and confocal live-cell imaging that Rec8 cleavage triggers chiasmata resolution during meiosis I and sister centromere disjunction during meiosis II, while Scc1 cleavage triggers sister chromatid disjunction in the first embryonic mitosis, demonstrating a dramatic transition from Rec8- to Scc1-containing cohesin at fertilization. Crucially, activation of an ectopic Rec8 transgene during the growing phase of Rec8(TEV)(/TEV) oocytes does not prevent TEV-mediated bivalent destruction, implying little or no cohesin turnover for ≥2 wk during oocyte growth. We suggest that the inability of oocytes to regenerate cohesion may contribute to age-related meiosis I errors.
Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
Kikuë
K
Tachibana-Konwalski
Jonathan
J
Godwin
Louise
L
van der Weyden
Lysie
L
Champion
Nobuaki R
NR
Kudo
David J
DJ
Adams
Kim
K
Nasmyth
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D002503:Centromere / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D005260:Female; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000254:growth & development* / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D010450:Endopeptidases; D009687:Nuclear Proteins; D010750:Phosphoproteins; D000097722:Cohesins; C465863:Rec8 protein, mouse; C099488:TEV protease