Effects Of Short-chain Acyl-CoA Dehydrogenase On Cardiomyocyte Apoptosis

ObjectiveShort-chain acyl-CoA dehydrogenase(SCAD), a key enzyme of fatty acid oxidation,plays an important role in the development of heart. SCAD is the first enzyme of fatty acidβ-oxidation, which caytalyses the short-chain acyl-CoA. In the present study we aim to determin the role of SCAD cardiomyocyte apoptosis. We also investigate regulations of AMPK/PPARα/SCAD signal pathways in cardiomyocyte apoptosis in order to explore a new target to prevent cardiomyocyte apoptosis.Methods1. The neonatal rat cardiomyocytes treated with tert-butyl hydroperoxide(t BHP) were used as the model of cardiomyocyte apoptosis. Cell viability and expression of SCAD in cardiomyocytes were measured.2. The optimal interfrence sequence 1186 was treated cells for 72 h, then we detected the apoptosis rate of cells by Hoechst 33258 nucleus staining and flow cytometry assay.Expression of SCAD, Bcl-2, Bax, cleaved caspase3, enzyme activity of SCAD, free fatty acid and ATP content in the cardiomyocytes were detected.3. Cells were pretreated with PPARα activator fenofibrate for 30 min, then stimulated with t BHP or si RNA-1186. The apoptosis rate of cells was evaluated by Hoechst 33258 nucleus staining and flow cytometry assay. Expression of SCAD and PPARα, Bcl-2, Bax,cleaved caspase3, enzyme activity of SCAD, free fatty acid and ATP content in the cardiomyocytes were detected.4. Cells were pretreated with AMPK activator AICAR for 30 min, then stimulated with t BHP for 6 h. The apoptosis rate of cells was evaluated by Hoechst 33258 nucleus staining and flow cytometry assay. Expression of SCAD, PPARα and p-AMPK, Bcl-2,Bax, cleaved caspase3, enzyme activity of SCAD, free fatty acid and ATP content in the cardiomyocytes were detected.Results1. MTT assay result demonstrated that cell viability changes with the various concentration of t BHP in different time. The cell viability is 50% when used with 200 μM t BHP for 6 h. In the results of Western Blotting and Real-time PCR, the expression of SCAD markedly decreased with 200 μM t BHP for 6 or 8 h.2. Compared with the control group, the expression of SCAD, enzyme activity of SCAD and the content of ATP were significantly decreased in t BHP or si RNA-1186 group.While, the free fatty acid content was significantly increased. Meanwhile, in t BHP or si RNA-1186 group, the cell apoptotic and the expression of cleaved caspase3 were significantly incresed, but the the decrease of the Bcl-2/Bax ratio.3. Compared with si RNA-1186 group, cardiomyocytes pretreated with fenofibrate had an increased expression of SCAD and PPARα, an increased enzyme activity of SCAD, a decreased content of free fatty acids and an increased ATP content. Similarily, fenofibrate can increase expression of SCAD and PPARα, the enzyme activity of SCAD, the ATP content and decrease the free fatty acid content in t BHP treated cardiomyocytes. What’s more, fenofibrate attenuated t BHP or si RNA induced cardiomyocyte apoptosis.4. Compared with the control group, t BHP treatment significantly decreased the expression of p-AMPKα and PPARα. Pretreatment with the AMPK activator AICAR significantly abrogated the effects in t BHP-treated cardiomyocytes compared with the cells treated with t BHP alone.ConclusionIn summary, our study demonstrated that SCAD played an important role in cardiomyocyte apoptosis, which could be regulated by AMPK/PPARα/SCAD signal pathway. These novel findings demonstrated that SCAD may be as a new target to prevent the development of heart failure.