Expression of BRG1, a human SWI/SNF component, affects the organisation of actin filaments through the RhoA signalling pathway
2002 (English)In: Journal of Cell Science, ISSN 0021-9533, Vol. 115, no 3, 2735-2745 p.Article in journal (Refereed) Published
The human BRG1 (brahma-related gene 1) protein is a component of the SWI/SNF family of the ATP-dependent chromatin remodelling complexes. We show here that expression of the BRG1 protein, but not of an ATPase-deficient BRG1 protein, in BRG1-deficient SW13 cells alters the organisation of actin filaments. BRG1 expression induces the formation of thick actin filament bundles resembling stress-fibres, structures that are rarely seen in native SW13 cells. BRG1 expression does not influence the activity state of the RhoA-GTPase, which is involved in stress-fibre formation. We find that RhoA is equally activated by stimuli, such as serum, in BRG1-expressing cells, ATPase-deficient BRG1-expressing cells and native SW13 cells. However, the activation of RhoA by lysophosphatidic acid and serum does not trigger the formation of stress-fibre-like structures in SW13 cells. Activation of the RhoA-GTPase in BRG1-expressing cells induces stress-fibre-like structures, indicating that the BRG1 can couple RhoA activation to stress-fibre formation. At least two downstream effectors are involved in stress-fibre formation, Rho-kinase/ROCK and Dia. BRG1 expression, but not the expression of the ATP-deficient BRG1, increases the protein level of ROCK1, one form of the Rho-kinase/ROCK. That this is of importance is supported by the findings that an increased Rho-kinase/ROCK activity in SW13 cells, obtained by overexpressing wild-type ROCK1 and ROCK2, induces stress-fibre formation. No specificity between the two Rho-kinase/ROCK forms exists. Our results suggest that the BRG1 protein affects the RhoA pathway by increasing the protein level of ROCK1, which allows stress-fibre-like structures to form.
Place, publisher, year, edition, pages
Company of Biologists Ltd. , 2002. Vol. 115, no 3, 2735-2745 p.
BRG1; SWI/SNF; actin filament organisation; RhoA; Rho kinases
IdentifiersURN: urn:nbn:se:su:diva-23252OAI: oai:DiVA.org:su-23252DiVA: diva2:190930
Part of urn:nbn:se:su:diva-2062004-08-202004-08-202010-01-05Bibliographically approved