The Rac and Rho hall of fame: a decade of hypertrophic signaling hits.
Over the last decade, the Rho family GTPases have gained considerable recognition as powerful regulators of actin cytoskeletal organization. As with many high profile signal transducers, these molecules soon attracted the attention of the cardiovascular research community. Shortly thereafter, two prominent members known as RhoA and Rac1 were linked to agonist-induced gene expression and myofilament organization using the isolated cardiomyocyte cell model. Subsequent creation of transgenic mouse lines provided evidence for more complex roles of RhoA and Rac1 signaling. Clues from in vitro and in vivo studies suggest the involvement of numerous downstream targets of RhoA and Rac1 signaling including serum response factor, NF-kappaB, and other transcription factors, myofilament proteins, ion channels, and reactive oxygen species generation. Which of these contribute to the observed phenotypic effects of enhanced RhoA and Rac activation in vivo remain to be determined. Current research efforts with a more translational focus have used statins or Rho kinase blockers to assess RhoA and Rac1 as targets for interventional approaches to blunt hypertrophy or heart failure. Generally, salutary effects on remodeling and ischemic damage are observed, but the broad specificity and multiple cellular targets for these drugs within the myocardium demands caution in interpretation. In this review, we assess the evolution of knowledge related to Rac1 and RhoA in the context of hypertrophy and heart failure and highlight the direction that future exploration will lead.
Department of Pharmacology, University of California, San Diego, USA.
Joan Heller
JH
Brown
Dominic P
DP
Del Re
Mark A
MA
Sussman
D000818:Animals; D006332:Cardiomegaly / Q000188:drug therapy / Q000209:etiology*; D050991:GATA4 Transcription Factor / Q000378:metabolism; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000502:physiology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D032383:Myocytes, Cardiac / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D017382:Reactive Oxygen Species; D026362:Serum Response Factor / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D020257:Ventricular Remodeling; D020830:rac1 GTP-Binding Protein / Q000502:physiology*; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000502:physiology*
D050991:GATA4 Transcription Factor; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D026362:Serum Response Factor; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein