Current Hypertension Reports

, Volume 5, Issue 1, pp 66–72 | Cite as

The role of RhoA and Rho-associated kinase in vascular smooth muscle contraction

  • Karl Swärd
  • Mitsuo Mita
  • David P. Wilson
  • Jing Ti Deng
  • Marija Susnjar
  • Michael P. Walsh


A variety of contractile agonists trigger activation of the small GTPase RhoA. An important target of activated RhoA in smooth muscle is Rho-associated kinase (ROK), one of the downstream targets that is the myosin binding subunit (MYPT1) of myosin light chain phosphatase (MLCP). Phosphorylation of MYPT1 at T695 by activated ROK results in a decrease in phosphatase activity of MLCP and an increase in myosin light chain (LC20) phosphorylation catalyzed by Ca2+/calmodulin-dependent myosin light chain kinase and/or a distinct Ca2+-independent kinase. LC20 phosphorylation in turn triggers cross-bridge cycling and force development. ROK also phosphorylates the cytosolic protein CPI-17 (at T38), which thereby becomes a potent inhibitor of MLCP. The RhoA/ROK pathway has been implicated in the tonic phase of force maintenance in response to various agonists, with no evident role in the phasic response, suggesting this pathway as a potential target for antihypertensive therapy. Indeed, ROK inhibitors restore normal blood pressure in several rat hypertensive models.


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Copyright information

© Current Science Inc. 2003

Authors and Affiliations

  • Karl Swärd
  • Mitsuo Mita
  • David P. Wilson
  • Jing Ti Deng
  • Marija Susnjar
  • Michael P. Walsh
    • 1
  1. 1.Smooth Muscle Research Group and Department of Biochemistry and Molecular BiologyUniversity of Calgary Faculty of MedicineCalgaryCanada

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