ISOCITRATE DEHYDROGENASE 2 INHIBITION INDUCES ENDOTHELIAL SENESCENCE BY SUPPRESSION OF MITOPHAGY AND INCREASED ROS PRODUCTION

Objective: Endothelial senescence impairs vascular function and thus is a primary event of age-related vasculature diseases. Isocitrate dehydrogenase 2 (IDH2) plays an important role in inducing alpha-ketoglutarate (alpha-KG) production and preserving mitochondrial function. However, the mechanism and regulation of IDH2 in endothelial senescence have not been elucidated. Design and method: We confirmed vascular endothelial senescence using human umbilical vein endothelial cells(HUVECs) and IDH2 Knockout mouse. Results: We demonstrated that downregulation of IDH2 induced accumulation of miR-34b/c, which impaired mitophagy and elevated mitochondrial reactive oxygen species (ROS) levels by inhibiting mitophagy-related markers (PTEN-induced putative kinase 1 (PINK1), Parkin, LC-II/LC3-I, and p62) and attenuating Sirtuin deacetylation 3 (Sirt3) expression. The mitochondrial dysfunction induced by IDH2 deficiency disrupted cell homeostasis and the cell cycle and led to endothelial senescence. However, miR-34b/c inhibition or alpha-KG supplementation restored Sirt3, PINK1, Parkin, LC-II/LC3-I, p62, and mitochondrial ROS levels, subsequently alleviating endothelial senescence. Conclusions: This study demonstrates that IDH2 deficiency is critical for the suppression of alpha-KG levels, which induced endothelial senescence via miR-34b/c inhibition of mitophagy and mitochondrial ROS elevation in endothelial cells (Figure 7). Therefore, the IDH2/alpha-KG/miR-34b/c axis may provide a potential therapeutic target for age-related vascular diseases.