Mitochondrial pyruvate carrier 2 mediates mitochondrial dysfunction and apoptosis in high glucose-treated podocytes

Podocytes play an important role in the development of diabetic kidney disease (DKD). Mitochondria are the source of energy for cell survival, and mitochondrial abnormalities have been shown to contribute to podocyte injury in DKD. In high glucose (HG)-treated podocytes, mitochondrial function and dynamics are abnormal, and intracellular metabolism is often disrupted. However, the molecular mechanism is still unclear. Mitochondrial pyruvate carrier 2 (MPC2) mediates pyruvate transport from the cytoplasm to the mitochondrial matrix, which determines the cellular energy supply and cell survival. Here, we hypothesize that MPC2 damages mitochondria and induces apoptosis in HG-treated podocytes.

We used Western blotting, immunofluorescence and immunoprecipitation to detect the expression of MPC2 in HG-treated podocytes. Pyruvate levels were measured to evaluate metabolic station. Mitochondrial membrane potential (MMP) was measured by inverted fluorescence microscopy and flow cytometry. Mitochondrial morphology was assayed by MitoTracker Red staining, and cellular apoptosis was examined by flow cytometry. Furthermore, we treated podocytes with UK5099 and MPC2 siRNA to assess the outcomes of UK5099 treatment and MPC2 knockdown.

Intracellular pyruvate accumulated, the mitochondria were damaged and cellular apoptosis increased in podocytes cultured with HG compared to that in control podocytes. MPC2 acetylation was significantly increased in HG-treated podocytes. Furthermore, the mitochondrial morphology changed, the MMP decreased, and cellular apoptosis increased. Inhibition of MPC2 function by UK5099 or MPC2 knockdown by siRNA produced the same abnormal effects observed following treatment with HG.

MPC2 may mediate mitochondrial dysfunction in HG-treated podocytes, ultimately leading to cell apoptosis.