[Effects of mitochondrial aldehyde dehydrogenase 2 on autophagy-associated proteins in neonatal rat myocardial fibroblasts cultured in high glucose].

OBJECTIVE:To investigate whether autophagy mediates the effects of aldehyde dehydrogenase 2 (ALDH2) on the proliferation of neonatal rat cardiac fibroblasts cultured in high glucose. METHODS:Cardiac fibroblasts were isolated from neonatal (within 3 days) SD rats and subcultured. The fibroblasts of the third passage, after identification with immunofluorescence staining for vimentin, were treated with 5.5 mmol/L glucose (control group), 30 mmol/L glucose (high glucose group), or 30 mmol/L glucose in the presence of Alda-1 (an ALDH2 agonist), daidzin (an ALDH2 2 inhibitor), or both. Western blotting was employed to detect ALDH2, microtubule-associated protein 1 light chain 3B subunit (LC3B) and Beclin-1 in the cells, and a hydroxyproline detection kit was used for determining hydroxyproline content in cell culture medium; CCK- 8 kit was used for assessing the proliferation ability of the cardiac fibroblasts after the treatments. RESULTS:Compared with the control cells, the cells exposed to high glucose exhibited obviously decreased expressions of ALDH2, Beclin-1 and LC3B and increased cell number and hydroxyproline content in the culture medium. Treatment of the high glucose-exposed cells with Alda-1 significantly increased Beclin-1, LC3B, and ALDH2 protein expressions and lowered the cell number and intracellular hydroxyproline content, whereas the application of daidzin resulted in reverse changes in the expressions of ALDH2, Beclin-1 and LC3B, viable cell number and intracellular hydroxyproline content in high glucose-exposed cells. CONCLUSIONS:Mitochondrial ALDH2 inhibits the proliferation of neonatal rat cardiac fibroblasts induced by high glucose, and the effect is possibly mediated by the up-regulation of autophagy-related proteins Beclin-1 and LC3B.

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