Cortical Mechanics and Meiosis II Completion in Mammalian Oocytes Are Mediated by Myosin-II and Ezrin-Radixin-Moesin (ERM) Proteins

Larson, S.; Lee, Hyo J.; Hung, Pei Hsuan; Matthews, Lauren M.; Robinson, Douglas N.; Evans, Janice Perry

doi:10.1091/mbc.e10-01-0066

Cited by 117 publications

(161 citation statements)

References 73 publications

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“…The compressing likely stiffens the cortex and prevents membrane protrusion. This interpretation is consistent with the demonstration that mouse oocyte cortical tension drops by 6 fold during oocyte maturation, presumably to permit the highly lopsided cytokinesis to produce polar bodies [Larson et al, 2010].…”

Section: Contractile Ring In Polar Body Emissionsupporting

confidence: 90%

Polar body emission

2012

Cytoskeleton

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Generation of a haploid female germ cell, the egg, consists of two rounds of asymmetric cell division (meiosis I and meiosis II), yielding two diminutive and nonviable polar bodies and a large haploid egg. Animal eggs are also unique in the lack of centrioles and therefore form meiotic spindles without the pre-existence of the two dominant microtubule organizing centers (centrosomes) found in mitosis. Meiotic spindle assembly is further complicated by the unique requirement of sister chromatid mono-oriented in meiosis I. Nonetheless, the eggs appear to adopt many of the same proteins and mechanisms described in mitosis, with necessary modifications to accommodate their special needs. Unraveling these special modifications will not only help understanding animal reproduction, but should also enhance our understanding of cell division in general. V C 2012 Wiley Periodicals, Inc

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Section: Contractile Ring In Polar Body Emissionsupporting

confidence: 90%

Polar body emission

2012

Cytoskeleton

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“…Myosin II was shown to cooperate with actin to mediate cortical tension in mouse oocyte [Larson et al, 2010]. In late MI, in response to the approaching chromatin signal, a cortical actomyosin ring structure above the spindle is established to drive polar body extrusion [Deng et al, 2003].…”

Section: Spindle Migration: Where and How The Force Is Generatedmentioning

confidence: 99%

Actin cytoskeleton in cell polarity and asymmetric division during mouse oocyte maturation

2012

Cytoskeleton

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Mammalian oocyte maturation involves two successive rounds of extremely asymmetric cell divisions (known as polar body extrusion) to generate a functional haploid egg. Successful polar body extrusion relies on establishment of an asymmetric spindle position and cortical polarity. Decades of studies using mouse oocytes as a model have revealed critical roles for a dynamic actin cytoskeleton in this process. Here, we review the contribution of actin to the critical events during oocyte meiotic cell divisions with an emphasis on recent advances in understanding the underlying molecular and physical mechanisms. V C 2012 Wiley Periodicals, Inc

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“…This region of the cortex, termed the actin cap, is electron-dense, and rich in F-actin [Shimizu, 1981[Shimizu, , 1983Longo and Chen, 1985;Maro et al, 1986;Heil-Chapdelaine and Otto, 1996;Ma et al, 2006;Sun and Schatten, 2006;Hamaguchi et al, 2007]. Myosin II heavy chains IIA and IIB and the active phosphorylated form of the myosin II regulatory light chain first colocalize with the actin cap and, before anaphase, reorganize into a ring surrounding it [Simerly et al, 1998;Deng et al, 2007;Larson et al, 2010;Wang et al, 2011].…”

Section: Oocyte Polarization: Preanaphase Cortical Differentiationmentioning

confidence: 99%

“…Accordingly, normal levels of global cortical stiffness are not required for outpocketing of the presumptive polar body cortex. Two-or threefold reduction of cortical stiffness via inhibition of contractility with the myosin light chain kinase (MLCK) inhibitor ML-7 or by expression of a dominant negative Radixin construct, respectively, blocked meiotic spindle rotation, but local extrusions occurred over the two anaphase chromatin masses [Larson et al, 2010]. Thus, mammalian oocytes appear to employ a different mechanism of polar body outpocketing that remains to be investigated.…”

Section: Mechanics Of Pbe: Similarity To Blebsmentioning

confidence: 99%

Polar body cytokinesis

2012

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Polar body cytokinesis is the physical separation of a small polar body from a larger oocyte or ovum. This maternal meiotic division shares many similarities with mitotic and spermatogenic cytokinesis, but there are several distinctions, which will be discussed in this review. We synthesize results from many different model species, including those popular for their genetics and several that are more obscure in modern cell biology. The site of polar body division is determined before anaphase, by the eccentric, cortically associated meiotic spindle. Depending on the species, either the actin or microtubule cytoskeleton is required for spindle anchoring. Chromatin is necessary and sufficient to elicit differentiation of the associated cortex, via Ran-based signaling. The midzone of the anaphase spindle serves as a hub for regulatory complexes that elicit Rho activation, and ultimately actomyosin contractile ring assembly and contraction. Polar body cytokinesis uniquely requires another Rho family GTPase, Cdc42, for dynamic reorganization of the polar cortex. This is perhaps due to the considerable asymmetry of this division, wherein the polar body and the oocyte/ovum have distinct fates and very different sizes. Thus, maternal meiotic cytokinesis appears to occur via simultaneous polar relaxation and equatorial contraction, since the polar body is extruded from the spherical oocyte through the nascent contractile ring. As such, polar body cytokinesis is an interesting and important variation on the theme of cell division. V C 2012 Wiley Periodicals, Inc

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Cortical Mechanics and Meiosis II Completion in Mammalian Oocytes Are Mediated by Myosin-II and Ezrin-Radixin-Moesin (ERM) Proteins

Cited by 117 publications

References 73 publications

Polar body emission

Polar body emission

Actin cytoskeleton in cell polarity and asymmetric division during mouse oocyte maturation

Polar body cytokinesis

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