Melatonin alleviates high glucose-induced cardiomyocyte injury through suppressing mitochondrial FUNDC1-DRP1 axis.

Objectives: To use H9c2 cardiomyocytes to establish a diabetic cardiomyopathic model by exposing these cells to high glucose (HG), followed by treating them with melatonin (MEL) or plasmid vectors overexpressing FUN14 Domain Containing 1 (FUNDC1).

Methods: We employed quantitative real-time PCR, mitochondrial staining, and biochemical assays to measure the activity of various antioxidant and mitochondrial complex functions under various treatment conditions.

Key findings: Our results showed that HG induced the expression of FUNDC1 and increased mitochondrial oxidative stress and fragmentation, while MEL treatment reversed most of these pathological effects. Moreover, HG exposure activated dynamin-related protein 1 expression and its translocation to mitochondria. Modulation of AMP-activated protein kinase level was found to be another pathological hallmark. In silico molecular docking, analysis revealed that MEL could directly bind the catalytic groove of FUNDC1 through Van der Waal's force and hydrogen bonding. Finally, MEL ameliorated diabetic cardiomyopathy-induced mitochondrial injury through FUNDC1 in vivo.

Conclusions: Hyperglycemia induced mitochondrial fragmentation and altered electron transport chain complex functions, which could be ameliorated by MEL treatment, suggesting its potential as a cardiovascular therapeutic.