Miclxin, a Mic60/Mitofilin Inhibitor, Induces Rat H9c2 Cardiomyoblast Death by Inhibiting the Removal of Damaged Mitochondria

Mitochondrial dysfunction is a hallmark of numerous pathological conditions, including ischemia/reperfusion injury, stroke, myocardial infarction, neurodegeneration, and metabolic syndrome. As with all biological organelles, mitochondrial function is closely tied to mitochondrial structure. The inner mitochondrial membrane is a highly regulated compartment with extensive surface area that houses the electron transport chain, generates the membrane potential required for ATP synthesis, and forms the characteristic cristae folds. The mitochondrial inner membrane protein Mitofilin/Mic60 is a core component of the mitochondrial inner membrane organizing system and is essential for maintaining mitochondrial architecture and function. Recent studies show that loss of Mic60/Mitofilin during reperfusion determines the extent of myocardial infarct size after ischemia/reperfusion injury. Here, we investigated the effects and mechanisms of Miclxin, a novel Mic60/Mitofilin inhibitor, in H9c2 cardiomyoblasts. Cultured rat H9c2 cells were incubated with 0, 5, 10, or 20 μM Miclxin. Cell viability was assessed using MTT assays, and cell death was measured by flow cytometry with propidium iodide. Mitochondrial membrane potential was evaluated using MitoTracker Red CMXROS, mitophagy was detected with Mitophagy Detection Kits, mitochondrial morphology was examined by electron microscopy, and protein expression was analyzed by Western blotting and immunofluorescence. After 24 hours of treatment, Miclxin reduced cell viability in a dose-dependent manner, corresponding to a marked decrease in Mic60 protein levels by Western blot and immunocytochemistry. Reduced viability was associated with impaired mitophagy and increased mitochondrial structural abnormalities. These findings suggest that Miclxin decreases Mic60 levels and reduces cardiomyoblast viability by disrupting mitochondrial structure and function through inhibition of mitophagy. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.