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Curr Biol. 2012 Feb 7;22(3):213-9. doi: 10.1016/j.cub.2011.12.019. Epub 2012 Jan 5.

The RhoGAP domain of CYK-4 has an essential role in RhoA activation.

Author information

1
Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA.

Erratum in

  • Curr Biol. 2012 Feb 7;22(3):259.

Abstract

Cytokinesis in animal cells is mediated by a cortical actomyosin-based contractile ring. The GTPase RhoA is a critical regulator of this process as it activates both nonmuscle myosin and a nucleator of actin filaments [1]. The site at which active RhoA and its effectors accumulate is controlled by the microtubule-based spindle during anaphase [2]. ECT-2, the guanine nucleotide exchange factor (GEF) that activates RhoA during cytokinesis, is regulated by phosphorylation and subcellular localization [3-5]. ECT2 localization depends on interactions with CYK-4/MgcRacGAP, a Rho GTPase-activating protein (GAP) domain containing protein [5, 6]. Here we show that, contrary to expectations, the Rho GTPase-activating protein (GAP) domain of CYK-4 promotes activation of RhoA during cytokinesis. Furthermore, we show that the primary phenotype caused by mutations in the GAP domain of CYK-4 is not caused by ectopic activation of CED-10/Rac1 and ARX-2/Arp2. However, inhibition of CED-10/Rac1 and ARX-2/Arp2 facilitates ingression of weak cleavage furrows. These results demonstrate that a GAP domain can contribute to activation of a small GTPase. Furthermore, cleavage furrow ingression is sensitive to the balance of contractile forces and cortical tension.

PMID:
22226748
PMCID:
PMC3285270
DOI:
10.1016/j.cub.2011.12.019
[Indexed for MEDLINE]
Free PMC Article

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