title: Rho-GTPase effector ROCK phosphorylates cofilin in actin-meditated cytokinesis during mouse oocyte meiosis.
abstract: During oocyte meiosis, a spindle forms in the central cytoplasm and migrates to the cortex. Subsequently, the oocyte extrudes a small body and forms a highly polarized egg; this process is regulated primarily by actin. ROCK is a Rho-GTPase effector that is involved in various cellular functions, such as stress fiber formation, cell migration, tumor cell invasion, and cell motility. In this study, we investigated possible roles for ROCK in mouse oocyte meiosis. ROCK was localized around spindles after germinal vesicle breakdown and was colocalized with cytoplasmic actin and mitochondria. Disrupting ROCK activity by RNAi or an inhibitor resulted in cell cycle progression and polar body extrusion failure. Time-lapse microscopy showed that this may have been due to spindle migration and cytokinesis defects, as chromosomes segregated but failed to extrude a polar body and then realigned. Actin expression at oocyte membranes and in cytoplasm was significantly decreased after these treatments. Actin caps were also disrupted, which was confirmed by a failure to form cortical granule-free domains. The mitochondrial distribution was also disrupted, which indicated that mitochondria were involved in the ROCK-mediated actin assembly. In addition, the phosphorylation levels of Cofilin, a downstream molecule of ROCK, decreased after disrupting ROCK activity. Thus, our results indicated that a ROCK-Cofilin-actin pathway regulated meiotic spindle migration and cytokinesis during mouse oocyte maturation.
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Duan
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Xiao-Xin
authors.initials: XX
authors.lastname: Dai
authors.forename: Hong-Lin
authors.initials: HL
authors.lastname: Liu
authors.forename: Xiang-Shun
authors.initials: XS
authors.lastname: Cui
authors.forename: Nam-Hyung
authors.initials: NH
authors.lastname: Kim
authors.forename: Zhen-Bo
authors.initials: ZB
authors.lastname: Wang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Shao-Chen
authors.initials: SC
authors.lastname: Sun
mesh_terms: D000199:Actins / Q000502:physiology*; D000577:Amides / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D051338:Cofilin 1 / Q000378:metabolism*; D048749:Cytokinesis / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D020558:GTP Phosphohydrolases / Q000378:metabolism; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D059705:Polar Bodies / Q000187:drug effects / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D051338:Cofilin 1; D004791:Enzyme Inhibitors; D011725:Pyridines; C108830:Y 27632; D054460:rho-Associated Kinases; D020558:GTP Phosphohydrolases
keywords: ROCK; actin; cytokinesis; oocyte polarization; spindle migration