Transformation by the Rho-specific guanine nucleotide exchange factor Dbs requires ROCK I-mediated phosphorylation of myosin light chain.
Dbs was identified in a cDNA-based expression screen for sequences that can cause malignant growth when expressed in murine fibroblasts. In previous studies we have shown that Dbs is a Rho-specific guanine nucleotide exchange factor that can activate RhoA and/or Cdc42 in a cell-specific manner. In this current study we have used a combination of genetic and pharmacological approaches to examine the relative contributions of RhoA x PRK and RhoA x ROCK signaling to Dbs transformation. Our analysis indicates that ROCK is activated in Dbs-transformed cells and that Dbs transformation is dependent upon ROCK I activity. In contrast, there appears to be no requirement for PRK activation in Dbs transformation. Dbs transformation is also associated with increased phosphorylation of myosin light chain and stress fiber formation, both of which occur in a ROCK-dependent manner. Suppression of myosin light chain expression by small interfering RNAs impairs Dbs focus formation, thus establishing a direct link between actinomyosin contraction and Rho-specific guanine nucleotide exchange factor transformation.
Liu
Zhuoming
Z
Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA.
Kostenko
Elena V
EV
Mahon
Gwendolyn M
GM
Olabisi
Oyenike O
OO
Whitehead
Ian P
IP
D000818:Animals; D015153:Blotting, Western; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018994:Myosin Light Chains / Q000378:metabolism*; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering; D064067:Rho Guanine Nucleotide Exchange Factors; D054460:rho-Associated Kinases
D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; C092132:Mcf2l protein, mouse; D018994:Myosin Light Chains; D034741:RNA, Small Interfering; D064067:Rho Guanine Nucleotide Exchange Factors; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases