Abstract 3214: MicroRNA-1 and IGF-1 Signaling Pathway in Myocardial Cell Apoptosis Induced by High Glucose
High glucose (HG) state is closely related to diabetic complications and one main pathogenesis involves apoptosis of cardiomyocytes. microRNAs are novel biomarkers, modulators and therapeutic targets for heart disease. The microRNAs miR-1 and miR-133 are preferentially expressed in cardiac muscles. Insulin-like growth factor (IGF-1) induces survival of multiple cell types. This study was to investigate whether HG state could induce apoptosis of H9C2 rat ventricular cells through microRNA and IGF-1 signaling pathway. We found that glucose increased both miR-1 (3.2 ± 0.4 fold increase vs. control, p<0.05) and miR-133 expression (3.6 ± 0.5 fold increase vs. control, p<0.05) determined by the mirVana qRT-PCR miRNA detection assay, which was dose- and time-dependent effects (25 mM at 24 h, rather than 5 mM at 24 h and 48 h). High glucose (25 mM), but not low dose glucose (5 mM), decreased mitochondrial membrane potential (58.5 ± 6.9 % reduction at 48h) assessed by Rh-123, increased cytochrome C release (321 ± 32.6 % increase at 72 h), and induced apoptosis as detected by Death ELISA (Glucose vs. control = 0.61 ± 0.07 vs. 0.18 ± 0.09 absorbance, p<0.02) and cell viability assays. Co-incubation of H9C2 cells with glucose and IGF-1, IGF-1 (50 ng/ml) dose-dependently blocked the glucose induced mitochondrial dysfunction, cytochrome C release and apoptosis. The anti-apoptotic function of the IGF-1 was associated with increased Akt phosphorylation and increased Akt kinase activity (p<0.02). Using prediction algorithms, we identified 3′-untranslated regions of IGF-1 gene are the target of miR-1, but not the target of miR-133. Moreover, overexpression of specific miR-1 mimics, but not miR-133 mimics, blocked the capacity of the IGF-1 to prevent glucose-induced mitochondrial dysfunction, cytochrome C release and apoptosis. In conclusion, our data demonstrate that IGF-1 inhibits glucose-induced mitochondrial dysfunction, cytochrome C release and apoptosis through miR-1, and suggest that activation of IGF-1 signaling pathway may be a useful strategy to prevent diabetic cardiomyopathy.
This research has received full or partial funding support from the American Heart Association, AHA South Central Affiliate (Arkansas, New Mexico, Oklahoma & Texas).