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Nat Cell Biol. 1999 Aug;1(4):242-8.

Rac regulates phosphorylation of the myosin-II heavy chain, actinomyosin disassembly and cell spreading.

Author information

1
The Netherlands Cancer Institute, Division of Cell Biology, Amsterdam, The Netherlands.

Abstract

GTPases of the Rho family regulate actinomyosin-based contraction in non-muscle cells. Activation of Rho increases contractility, leading to cell rounding and neurite retraction in neuronal cell lines. Activation of Rac promotes cell spreading and interferes with Rho-mediated cell rounding. Here we show that activation of Rac may antagonize Rho by regulating phosphorylation of the myosin-II heavy chain. Stimulation of PC12 cells or N1E-115 neuroblastoma cells with bradykinin induces phosphorylation of threonine residues in the myosin-II heavy chain; this phosphorylation is Ca2+ dependent and regulated by Rac. Both bradykinin-mediated and constitutive activation of Rac promote cell spreading, accompanied by a loss of cortical myosin II. Our results identify the myosin-II heavy chain as a new target of Rac-regulated kinase pathways, and implicate Rac as a Rho antagonist during myosin-II-dependent cell-shape changes.

PMID:
10559923
DOI:
10.1038/12068
[Indexed for MEDLINE]

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