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Dev Cell September 1, 2008; 15 (3): 386-400.

Polar body emission requires a RhoA contractile ring and Cdc42-mediated membrane protrusion.

Zhang X , Ma C , Miller AL , Katbi HA , Bement WM , Liu XJ .

Vertebrate oocyte maturation is an extreme form of asymmetric cell division, producing a mature egg alongside a diminutive polar body. Critical to this process is the attachment of one spindle pole to the oocyte cortex prior to anaphase. We report here that asymmetric spindle pole attachment and anaphase initiation are required for localized cortical activation of Cdc42, which in turn defines the surface of the impending polar body. The Cdc42 activity zone overlaps with dynamic F-actin and is circumscribed by a RhoA-based actomyosin contractile ring. During cytokinesis, constriction of the RhoA contractile ring is accompanied by Cdc42-mediated membrane outpocketing such that one spindle pole and one set of chromosomes are pulled into the Cdc42 enclosure. Unexpectedly, the guanine nucleotide exchange factor Ect2, which is necessary for contractile ring formation, does not colocalize with active RhoA. Polar body emission thus requires a classical RhoA contractile ring and Cdc42-mediated membrane protrusion.

PubMed ID: 18804436
PMC ID: PMC3549423
Article link: Dev Cell
Grant support: [+]
Genes referenced: actl6a cdc42 ect2 rhoa rhoa.2

References [+] :
Bement, Rho GTPase activity zones and transient contractile arrays. 2006, Pubmed

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