Activation of Akt/GSK-3beta signaling pathway is involved in intermedin(1-53) protection against myocardial apoptosis induced by ischemia/reperfusion.
Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide family. We investigated the cardioprotective mechanism of IMD(1-53) in the in vivo rat model of myocardial ischemia/reperfusion (I/R) injury and in vitro primary neonatal cardiomyocyte model of hypoxia/reoxygenation (H/R). Myocardial infarct size was measured by 2,3,5-triphenyl tetrazolium chloride staining. Cardiomyocyte viability was determined by trypan blue staining, cell injury by lactate dehydrogenase (LDH) leakage, and cardiomyocyte apoptosis by terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling assay, Hoechst staining, gel electrophoresis and caspase 3 activity. The translocation of mitochondrial cytochrome c of myocardia and expression of apoptosis-related factors Bcl-2 and Bax, phosphorylated Akt and phosphorylated GSK-3beta were determined by western blot analysis. IMD(1-53) (20 nmol/kg) limited the myocardial infarct size in rats with I/R; the infarct size was decreased by 54%, the apoptotic index by 30%, and caspase 3 activity by 32%; and the translocation of cytochrome c from mitochondria to cytosol was attenuated. IMD(1-53) increased the mRNA and protein expression of Bcl-2 and ratio of Bcl-2 to Bax by 81 and 261%, respectively. IMD(1-53) (1 x 10(-7) mol/L) inhibited the H/R effect in cardiomyocytes by reducing cell death by 43% and LDH leakage by 16%; diminishing cellular apoptosis; decreasing caspase 3 activity by 50%; and increasing the phosphorylated Akt and GSK-3beta by 41 and 90%, respectively. The cytoprotection of IMD(1-53) was abolished with LY294002, a PI3K inhibitor. In conclusion, IMD(1-53) exerts cardioprotective effect against myocardial I/R injury through the activation of the Akt/GSK-3beta signaling pathway to inhibit mitochondria-mediated myocardial apoptosis.
Song
Jun-Qiu
JQ
Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China.
Teng
Xu
X
Cai
Yan
Y
Tang
Chao-Shu
CS
Qi
Yong-Fen
YF
D053607:Adrenomedullin / Q000502:physiology*; D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000502:physiology*; D000071679:Glycogen Synthase Kinase 3 beta; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009203:Myocardial Infarction / Q000473:pathology / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009479:Neuropeptides / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
C499411:Adm2 protein, rat; D002867:Chromones; D009025:Morpholines; D009479:Neuropeptides; D053607:Adrenomedullin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3