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MgcRacGAP promotes GTPase flux to maintain a tightly focused zone of Rho activity during cytokinesis
Author(s) -
Miller Ann Louise,
Bement William M
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a994-b
Subject(s) - cytokinesis , microbiology and biotechnology , mitosis , gtpase , microtubule , actin , cleavage furrow , small gtpase , chemistry , biology , cell , cell division , biochemistry , signal transduction
How do microtubules of the mitotic spindle specify the position where the actomyosin‐based contractile ring will form during cytokinesis? Prior to contractile ring assembly, spindle microtubules precisely localize proteins that regulate the small GTPase Rho to the cell equator. These Rho regulators then direct formation of a localized zone of high Rho activity, which promotes the actomyosin contractility necessary for cytokinesis. We are examining the roles of the Rho regulator MgcRacGAP during cytokinesis in Xenopus embryos. We find that MgcRacGAP is localized to the contracting furrow and is required for cytokinesis. Disruption of MgcRacGAP’s GAP activity leads to Rho activity zones with increased intensity, breadth, and instability compared to controls. Additionally, disruption of MgcRacGAP’s GAP activity promotes increased accumulation of downstream targets of Rho at the furrow. We propose that during cytokinesis MgcRacGAP inactivates any activated Rho that does not immediately interact with an effector protein, resulting in the constant flux of Rho through the GTPase cycle. In this way, cells maintain a focused zone of Rho activity to drive furrow formation and contraction. Funding: American Cancer Society and Helen Hay Whitney Postdoctoral Fellowships to ALM. NIH grant to WMB.