title: From ubiquitin-proteasomal degradation to CDK1 inactivation: requirements for the first polar body extrusion in mouse oocytes.
abstract: Completion of the first meiotic division, manifested by extrusion of the first polar body (PBI), depends on proteasomal degradation of cyclin B1 and securin and the subsequent respective CDK1 inactivation and chromosome segregation. We aimed at identifying the polyubiquitin signal that mediates proteasomal action and at a better characterization of the role of CDK1 inactivation at this stage of meiosis. Microinjections of mutated ubiquitin proteins into mouse oocytes revealed that interference with lysine-11 polyubiquitin chains abrogated chromosome segregation and reduced PBI extrusion by 63% as compared to WT ubiquitin-injected controls. Inactivation of CDK1 in oocytes arrested at first metaphase by a proteasome inhibitor fully rescued PBI extrusion. However, removal of CDK1 inhibition failed to allow progression to the second metaphase, rather, inducing PBI reengulfment in 62% of the oocytes. Inhibition of either PLK1 or MEK1/2 during the first anaphase changed spindle dimensions. The PLK1 inhibitor also blocked PBI emission and prevented RhoA translocation. Our results identified lysine-11 rather than the canonic lysine-48 ubiquitin chains as the degradation signal in oocytes resuming meiosis, further disclosing that CDK1 inactivation is necessary and sufficient for PBI emission. This information significantly contributes to our understanding of faulty chromosome segregation that may lead to aneuploidy.
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Pomerantz
authors.forename: Judith
authors.initials: J
authors.lastname: Elbaz
authors.forename: Inbal
authors.initials: I
authors.lastname: Ben-Eliezer
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Reizel
authors.forename: Yael
authors.initials: Y
authors.lastname: David
authors.forename: Dalia
authors.initials: D
authors.lastname: Galiani
authors.forename: Nava
authors.initials: N
authors.lastname: Nevo
authors.forename: Ami
authors.initials: A
authors.lastname: Navon
authors.forename: Nava
authors.initials: N
authors.lastname: Dekel
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D020090:Chromosome Segregation; D048749:Cytokinesis; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D020935:MAP Kinase Signaling System; D008540:Meiosis / Q000502:physiology; D051379:Mice; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism*; D059705:Polar Bodies / Q000166:cytology / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D064249:Securin; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000097869:Polo-Like Kinase 1
chemical_list: D016203:CDC2 Protein Kinase; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D064249:Securin; D025801:Ubiquitin; D020742:rhoA GTP-Binding Protein; D000097869:Polo-Like Kinase 1