Influence of cardiac-specific overexpression of insulin-like growth factor 1 on lifespan and aging-associated changes in cardiac intracellular Ca2+ homeostasis, protein damage and apoptotic protein expression.
A fall in circulating levels of cardiac survival factor insulin-like growth factor 1 (IGF-1) contributes to cardiac aging. To better understand the role of IGF-1 in cardiac aging, we examined the influence of cardiac IGF-1 overexpression on lifespan, cardiomyocyte intracellular Ca2+ homeostasis, protein damage, apoptosis and expression of pro- and anti-apoptotic proteins in young and old mice. Mouse survival rate was constructed by the Kaplan-Meier curve. Intracellular Ca2+ was evaluated by fura-2 fluorescence. Protein damage was determined by protein carbonyl formation. Apoptosis was assessed by caspase-8 expression, caspase-3 and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay. Pro- and anti-apoptotic proteins including Bax, p53, pp53, Bcl2, Omi/HtrA2, apoptosis repressor with caspase recruitment domain (ARC) and X-linked inhibitor of apoptosis protein (XIAP) were assessed by Western blot. Aging decreased plasma in IGF-1 levels, elevated myocyte resting intracellular Ca2+ levels, reduced electrically stimulated rise in intracellular Ca2+ and delayed intracellular Ca2+ decay associated with enhanced protein carbonyl formation, caspase-8 expression and caspase-3 activity in FVB mice, all of which with the exception of elevated resting intracellular Ca2+ were attenuated by IGF-1. Aging up-regulated expression of Bax, Bcl2 and ARC, down-regulated XIAP expression and did not affect p53, pp53 and Omi/HtrA2. The IGF-1 transgene attenuated or nullified aging-induced changes in Bax, Bcl2 and XIAP. Our data suggest a beneficial role for IGF-1 in aging-induced survival, cardiac intracellular Ca2+ homeostasis, protein damage and apoptosis possibly related to pro- and anti-apoptotic proteins.
Li
Qun
Q
Division of Pharmaceutical Sciences & Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA.
Ren
Jun
J
D000375:Aging / Q000378:metabolism*; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D016922:Cellular Senescence; D006706:Homeostasis; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008136:Longevity; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D007334:Insulin-Like Growth Factor I; D020169:Caspases; D002118:Calcium