title: RhoA-mediated FMNL1 regulates GM130 for actin assembly and phosphorylates MAPK for spindle formation in mouse oocyte meiosis.
abstract: Formin-like 1 (FMNL1) is a member of Formin family proteins which are the actin nucleators. Although FMNL1 activities have been shown to be essential for cell adhesion, cytokinesis, cell polarization and migration in mitosis, the functional roles of mammalian FMNL1 during oocyte meiosis remain uncertain. In this study, we investigated the functions of FMNL1 in mouse oocytes using specific morpholino (MO) microinjection and live cell imaging. Immunofluorescent staining showed that in addition to its cytoplasmic distribution, FMNL1 was primarily localized at the spindle poles after germinal vesicle breakdown (GVBD). FMNL1 knockdown caused the low rate of polar body extrusion and resulted in large polar bodies. Time-lapse microscopic and immunofluorescence intensity analysis indicated that this might be due to the aberrant actin expression levels. Cortical polarity was disrupted as shown by a loss of actin cap and cortical granule free domain (CGFD) formation, which was confirmed by a failure of meiotic spindle positioning. And this might be the reason for the large polar body formation. Spindle formation was also disrupted, which might be due to the abnormal localization of p-MAPK. These results indicated that FMNL1 affected both actin dynamics and spindle formation for the oocyte polar body extrusion. Moreover, FMNL1 depletion resulted in aberrant localization and expression patterns of a cis-Golgi marker protein, GM130. Finally, we found that the small GTPase RhoA might be the upstream regulator of FMNL1. Taken together, our data indicate that FMNL1 is required for spindle organization and actin assembly through a RhoA-FMNL1-GM130 pathway during mouse oocyte meiosis.
authors.affiliation: a College of Animal Science and Technology; Nanjing Agricultural University ; Nanjing , China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Xing
authors.initials: X
authors.lastname: Duan
authors.forename: Guang-Li
authors.initials: GL
authors.lastname: Zhang
authors.forename: Zhen-Bo
authors.initials: ZB
authors.lastname: Wang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Xiong
authors.forename: Shao-Chen
authors.initials: SC
authors.lastname: Sun
mesh_terms: D000199:Actins / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D001324:Autoantigens / Q000502:physiology*; D005260:Female; D000080865:Formins; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008540:Meiosis / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D008941:Spindle Apparatus / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D020742:rhoA GTP-Binding Protein
chemical_list: D000199:Actins; D001324:Autoantigens; C413382:Fmnl1 protein, mouse; D000080865:Formins; C097741:Golgin subfamily A member 2; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D020929:Mitogen-Activated Protein Kinase Kinases; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
keywords: FMNL1; actin; golgi; polar body extrusion; spindle organization