ROCK and mDia1 Antagonize in Rho-dependent Rac Activation in Swiss 3T3 Fibroblasts

Takahiro Tsuji, Toshimasa Ishizaki, Muneo Okamoto, Chiharu Higashida, Kazuhiro Kimura, Tomoyuki Furuyashiki, Yoshiki Arakawa, Raymond B Birge, Tetsuya Nakamoto, Hisamaru Hirai, Shuh Narumiya

J Cell Biol. 2002 May 27;157(5):819-30.

PMID: 12021256

Abstract:

The small GTPase Rho acts on two effectors, ROCK and mDia1, and induces stress fibers and focal adhesions. However, how ROCK and mDia1 individually regulate signals and dynamics of these structures remains unknown. We stimulated serum-starved Swiss 3T3 fibroblasts with LPA and compared the effects of C3 exoenzyme, a Rho inhibitor, with those of Y-27632, a ROCK inhibitor. Y-27632 treatment suppressed LPA-induced formation of stress fibers and focal adhesions as did C3 exoenzyme but induced membrane ruffles and focal complexes, which were absent in the C3 exoenzyme-treated cells. This phenotype was suppressed by expression of N17Rac. Consistently, the amount of GTP-Rac increased significantly by Y-27632 in LPA-stimulated cells. Biochemically, Y-27632 suppressed tyrosine phosphorylation of paxillin and focal adhesion kinase and not that of Cas. Inhibition of Cas phosphorylation with PP1 or expression of a dominant negative Cas mutant inhibited Y-27632-induced membrane ruffle formation. Moreover, Crk-II mutants lacking in binding to either phosphorylated Cas or DOCK180 suppressed the Y-27632-induced membrane ruffle formation. Finally, expression of a dominant negative mDia1 mutant also inhibited the membrane ruffle formation by Y-27632. Thus, these results have revealed the Rho-dependent Rac activation signaling that is mediated by mDia1 through Cas phosphorylation and antagonized by the action of ROCK.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP146986507	Y-27632 - CAS 146986-50-7		146986-50-7	Price
AP97627275	Rho Kinase Inhibitor II - CAS 97627-27-5		97627-27-5	Price

Catalog Number

Product Name

Structure

CAS Number

Price

AP146986507

Y-27632 - CAS 146986-50-7

146986-50-7

Price

AP97627275

Rho Kinase Inhibitor II - CAS 97627-27-5

97627-27-5

Price

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