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Transformation by the Rho-specific guanine nucleotide exchange factor Dbs requires ROCK I-mediated phosphorylation of

Zhuoming Liu1, Elena V Kostenko, Gwendolyn M Mahon

  • 1Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA.

The Journal of Biological Chemistry
|April 15, 2006
PubMed

Insights

Dbs protein drives malignant growth by activating RhoA signaling pathways. This transformation relies on ROCK I kinase activity, not PRK, and involves myosin light chain phosphorylation and stress fiber formation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Dbs is a Rho-specific guanine nucleotide exchange factor.
  • Dbs can activate RhoA and Cdc42, leading to malignant growth.
  • Previous studies identified Dbs in a screen for cancer-causing genes.

Purpose of the Study:

  • To investigate the roles of RhoA x PRK and RhoA x ROCK signaling in Dbs-induced transformation.
  • To determine the specific kinase dependencies for Dbs transformation.
  • To elucidate the downstream effectors involved in Dbs-mediated malignant growth.

Main Methods:

  • Utilized a combination of genetic and pharmacological approaches.
  • Examined ROCK I and PRK activation in Dbs-transformed cells.
  • Assessed myosin light chain phosphorylation and stress fiber formation.
  • Employed small interfering RNAs to suppress myosin light chain expression.

Main Results:

  • Dbs transformation is dependent on ROCK I activity, but not PRK.
  • ROCK activation leads to increased myosin light chain phosphorylation and stress fiber formation.
  • Suppression of myosin light chain impairs Dbs focus formation.

Conclusions:

  • Dbs-induced malignant transformation is critically dependent on ROCK I signaling.
  • Actinomyosin contraction, regulated by ROCK and myosin light chain, is essential for Dbs transformation.
  • Dbs acts as a Rho-specific guanine nucleotide exchange factor driving cancer progression via ROCK-mediated pathways.

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