p21-activated kinase improves cardiac contractility during ischemia-reperfusion concomitant with changes in troponin-T and myosin light chain 2 phosphorylation.
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 posttranslational 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.
Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 60612-7342, USA.
Michelle M
MM
Monasky
Domenico M
DM
Taglieri
Bindiya G
BG
Patel
Jonathan
J
Chernoff
Beata M
BM
Wolska
Yunbo
Y
Ke
R John
RJ
Solaro
D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D005260:Female; D047468:Immunoprecipitation; D051379:Mice; D057507:Mice, 129 Strain; D018345:Mice, Knockout; D009200:Myocardial Contraction; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D018994:Myosin Light Chains / Q000378:metabolism*; D010766:Phosphorylation; D020127:Recovery of Function; D013997:Time Factors; D020107:Troponin T / Q000378:metabolism*; D016277:Ventricular Function, Left; D017725:Ventricular Pressure; D054462:p21-Activated Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
C521958:Mylpf protein, mouse; D018994:Myosin Light Chains; D020107:Troponin T; C515905:Pak1 protein, mouse; D054462:p21-Activated Kinases