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Chicago Ridge, IL, United States

Monasky M.M.,35 S. Wolcott Ave | Taglieri D.M.,35 S. Wolcott Ave | Patel B.G.,35 S. Wolcott Ave | Chernoff J.,Fox Chase Cancer Center | And 4 more authors.
American Journal of Physiology - Heart and Circulatory Physiology | Year: 2012

p21-Activated kinase 1 (Pak1) is a serine/threonine kinase that activates protein phosphatase 2a, resulting in the dephosphorylation of cardiac proteins and increased myofilament Ca 2+ sensitivity. Emerging evidence indirectly indicates a role for Pak1 in ischemia-reperfusion (I/R), but direct evidence is lacking. We hypothesize that activation of the Pak1 signaling pathway is a cardioprotective mechanism that prevents or reverses the detrimental effects of ischemic injury by inducing post-translational modifications in myofilament proteins that ultimately improve cardiac contractility following ischemic insult. In the present study, we subjected ex vivo hearts from wild-type (WT) and Pak1-knockout (KO) mice to 20 min of global cardiac ischemia followed by 30 min of reperfusion. In the absence of Pak1, there was an exacerbation of the increased end-diastolic pressure and reduced left ventricular developed pressure occurring after I/R injury. ProQ analysis revealed an increase in troponin-T phosphorylation at baseline in Pak1-KO hearts compared with WT. Significantly decreased myosin light chain 2 (MLC2) phosphorylation in Pak1-KO hearts compared with WT after I/R injury was confirmed by Western immunoblotting. These data indicate that Pak1-KO hearts have reduced recovery of myocardial performance after global I/R injury concomitant with changes in troponin-T and MLC2 phosphorylation. Finally, a protein-protein association between Pak1 and MLC2, and Pak1 and troponin-T, was determined by coimmunoprecipitation. Thus, results of our study provide a basis for targeting a novel pathway, including Pak1, in the therapies for patients with ischemic events. © 2012 the American Physiological Society.

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