Arp2/3 Complex Regulates Asymmetric Division and Cytokinesis in Mouse Oocytes

Department of Animal Sciences, Chungbuk National University, Cheongju, Republic of Korea.
PLoS ONE (Impact Factor: 3.23). 04/2011; 6(4):e18392. DOI: 10.1371/journal.pone.0018392
Source: PubMed


Mammalian oocyte meiotic maturation involves oocyte polarization and a unique asymmetric division, but until now, the underlying mechanisms have been poorly understood. Arp2/3 complex has been shown to regulate actin nucleation and is widely involved in a diverse range of processes such as cell locomotion, phagocytosis and the establishment of cell polarity. Whether Arp2/3 complex participates in oocyte polarization and asymmetric division is unknown. The present study investigated the expression and functions of Arp2/3 complex during mouse oocyte meiotic maturation. Immunofluorescent staining showed that the Arp2/3 complex was restricted to the cortex, with a thickened cap above the meiotic apparatus, and that this localization pattern was depended on actin. Disruption of Arp2/3 complex by a newly-found specific inhibitor CK666, as well as by Arpc2 and Arpc3 RNAi, resulted in a range of effects. These included the failure of asymmetric division, spindle migration, and the formation and completion of oocyte cytokinesis. The formation of the actin cap and cortical granule-free domain (CGFD) was also disrupted, which further confirmed the disruption of spindle migration. Our data suggest that the Arp2/3 complex probably regulates oocyte polarization through its effect on spindle migration, asymmetric division and cytokinesis during mouse oocyte meiotic maturation.

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Available from: Sun Shao, Jul 29, 2015
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    • "Arp2/3 complex facilitates new F-actin polymerization in the dendritic actin cytoskeleton by binding to mother filaments. Actin polymerization regulated by Arp2/3 complex has been reported in pronucleus formation (Xiong et al., 2011), oocyte polarization (Sun et al., 2011), and embryo development (Sun et al., 2013). Importantly, the effect of the Arp2/3 complex on male fertility has not yet been reported in the literature. "
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    ABSTRACT: The actin-related protein 2/3 (Arp2/3) complex is critical for regulation of actin polymerization, which is associated with sperm motility and capacitation status. However, the function of the Arp2/3 complex in male fertility has not yet been fully elucidated. Therefore, this study was designed to investigate the role of the Arp2/3 complex in different processes in spermatozoa and its consequences on fertilization and early embryonic development. In this in vitro study, mouse spermatozoa were incubated with different concentrations (10, 100, and 500 μm) of CK-636, an Arp2/3 complex antagonist. Our results demonstrated that inhibition of the Arp2/3 complex by high concentrations (100 and 500 μm) of CK-636 induced hyper-activated motility and acrosomal reaction, whereas intracellular calcium and tyrosine phosphorylation levels in spermatozoa were inhibited. Moreover, exposure of spermatozoa to the highest concentration of CK-636 reduced fertilization and embryo development. Interestingly, fertilization was significantly increased after treatment with 100 μm CK-636, whereas embryonic development was significantly decreased. Therefore, we conclude that the Arp2/3 complex plays a decisive role in regulation of sperm function and male fertility via actin polymerization. We anticipate that the Arp2/3 complex may have clinical application as marker for male fertility and male contraceptive targeting. © 2015 American Society of Andrology and European Academy of Andrology.
    Full-text · Article · Jul 2015 · Andrology
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    • "In mammalian oocytes, dynamic actin polymerization and reorganization are essential for asymmetric spindle migration, polar body extrusion, and cytokinesis [1], [2]. Actin nucleators, proteins which promote actin polymerization [3], such as formin 2 [4], spire [5], and the Arp2/3 complex [6], [7] play essential roles in oocyte maturation. In addition with actin nucleators, nucleation-promoting factors (NPFs), which bind to and activate the Arp2/3 complex in response to Rho-GTPase signaling [3], are also important for oocyte maturation. "
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    ABSTRACT: Junction-mediating and regulatory protein(JMY) is a multifunctional protein with roles in the transcriptional co-activation of p53 and the regulation of actin nucleation promoting factors and, hence, cell migration; however, its role in the maturation of porcine oocytes is unclear. In the current study, we investigated functional roles of JMY in porcine oocytes. Porcine oocytes expressed JMY mRNA and protein, and the mRNA expression level decreased during oocyte maturation. Knockdown of JMY by RNA interference decreased the rate of polar body extrusion, validating its role in the asymmetric division of porcine oocytes. JMY knockdown also down-regulated the mRNA and protein levels of actin and Arp2/3. Furthermore, JMY accumulated in the nucleus in response to DNA damage, and JMY knockdown suppressed DNA damage-mediated p53 activation. In conclusion, our results show that JMY has important roles in oocyte maturation as a regulator of actin nucleation-promoting factors and an activator of p53 during DNA damage during DNA damages in porcine oocytes.
    Full-text · Article · Oct 2014 · PLoS ONE
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    • "The Arp2/3 complex and nucleation-promoting factors (NPFs) that associate with Arp2/3 have been shown to regulate the branched actin filament networks that are required for various cellular processes, including cell migration and adhesion151617, endocytosis1819, and establishing polarity during oocyte meiosis2021. Recent studies demonstrated that Arp2/3 complex and the associated NPFs WAVE2 and JMY regulated mammalian oocyte asymmetric division2223. Furthermore, WASH1 was found to be essential for Drosophila oogenesis associated with Arp2/3-mediated actin nucleation activity6. "
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    ABSTRACT: Prior to their fertilization, oocytes undergo asymmetric division, which is regulated by actin filaments. Recently, WASH complex were identified as actin nucleation promoting factors (NPF) that activated Arp2/3 complex. However, the roles of WASH complex remain uncertain, particularly for oocyte polarization and asymmetric division. Here, we examined the functions of two important subunits of a WASH complex, WASH1 and Strumpellin, during mouse oocyte meiosis. Depleting WASH1 or disrupting Strumpellin activity by WASH1 morpholino (MO) injection or Strumpellin antibody injection decreased polar body extrusion and caused oocyte symmetric division, and this may have been due to spindle formation and migration defects. Time lapse microscopy showed that actin filaments distribution and relative amount at the membrane and in the cytoplasm of oocytes was significantly decreased after disrupting WASH complex. In addition, Arp2/3 complex expression was reduced after WASH1 depletion. Thus, our data indicated that WASH complex regulated Arp2/3 complex and were required for cytokinesis and following polar body extrusion during mouse oocyte meiotic maturation.
    Full-text · Article · Jul 2014 · Scientific Reports
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