Heat stress activates AKT via focal adhesion kinase-mediated pathway in neonatal rat ventricular myocytes.
Heat stress (HS)-induced cardioprotection is associated with increased paxillin localization to the membrane fraction of neonatal rat ventricular myocytes (NRVM). The purpose of this study was 1) to examine the subcellular signaling pathways activated by HS; 2) to determine whether myocardial stress organizes and activates an integrated survival pathway; and 3) to investigate potential downstream cytoprotective proteins activated by HS. After HS, NRVM were subjected to chemical inhibitors (CI) designed to simulate ischemia by inhibiting both glycolysis and mitochondrial respiration. Protein kinase B (AKT) expression (wild type) was increased selectively with an adenoviral vector. Cell signaling was analyzed with Western blot analysis, while oncosis/apoptosis was assayed by measuring Trypan blue exclusion and/or terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. HS increased phosphorylation of focal adhesion kinase (FAK) at tyrosine 397 but did not adversely affect the viability of NRVM before CI. HS increased association between FAK and phosphatidylinositol 3-kinase as well as causing a significant increase in AKT activity. Increased expression of wild-type AKT protected myocytes from both oncotic and apoptotic cell death. Increased expression of a FAK inhibitor, FRNK, reduced AKT phosphorylation in response to HS both at time 0 and after 10 min of CI compared with myocytes expressing empty virus. We conclude that myocardial stress activates cytoskeleton-based signaling pathways that are associated with protection from lethal cell injury.
Dept. of Pathology, Wayne State Univ. Medical School, 540 East Canfield Ave., Detroit, MI 48201, USA.
Hongguang
H
Wei
Richard S
RS
Vander Heide
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D019610:Cytoprotection; D004734:Energy Metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism*; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D006352:Heart Ventricles / Q000201:enzymology; D006358:Hot Temperature; D020287:In Situ Nick-End Labeling; D008929:Mitochondria, Heart / Q000201:enzymology; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000517:prevention & control; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014161:Transduction, Genetic; D000099200:Scaffold Protein ILK
D004791:Enzyme Inhibitors; D051417:Focal Adhesion Kinase 1; D051418:Focal Adhesion Kinase 2; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000099200:Scaffold Protein ILK; C113183:FAK-related nonkinase; C496052:Ptk2 protein, rat