High glucose-induced mitochondrial fission promotes Müller cell activation via suppression of the Hippo pathway
摘要
Diabetic retinopathy (DR) is the leading cause of blindness in diabetic patients, in which high glucose (HG)-induced Müller cell activation constitutes a central pathological event. This study aimed to untangle the critical role and mechanism of mitochondrial fission in this process. We found that under HG conditions, the level of p-Drp1 was significantly elevated (P < 0.05), driving excessive mitochondrial fission. Functional experiments confirmed that artificially enhancing mitochondrial fission directly inhibited the Hippo signaling pathway (levels of core proteins p-MST1/2, p-LATS1, and p-YAP decreased, P < 0.05, and YAP translocated to the nucleus), thereby activating Müller cells (expression of marker proteins GS and Kir4.1 decreased, while expression of GFAP, AQP4, and inflammatory mediators IL-1β, IL-6, VEGF increased, P < 0.05). Key rescue experiments demonstrated that Drp1 silencing (reduced p-Drp1 level, P < 0.05) reversed the aforementioned activation; however, co-administration of the Hippo pathway inhibitor XMU-MP-1 re-induced cell activation, proving that the Hippo pathway is a necessary downstream mediator of mitochondrial fission. In a diabetic rat model, elevated p-Drp1, Hippo pathway inhibition, and cell activation were similarly observed; the mitochondrial fission inhibitor Mdivi-1 alleviated this pathological process, whereas XMU-MP-1 counteracted its protective effects. This study systematically elucidates, from ex vivo to in vivo, the causal regulatory axis of “HG- mitochondrial fission- Hippo pathway inhibition—Müller cell activation,” providing experimental evidence and a potential target for developing DR-targeted therapeutic strategies centered on intervening in mitochondrial dynamics.