Increased Ca2+transport across the mitochondria-associated membranes by Mfn2 inhibiting endoplasmic reticulum stress in ischemia/reperfusion kidney injury

Renal ischemia/reperfusion (I/R) injury, which leads to acute kidney injury (AKI), is a major cause of morbidity and mortality in a variety of clinical situations. This study aimed to investigate the protective role of Mfn2 during renal I/R injury. Overexpression of Mfn2 in NRK-52E rat renal tubular epithelial cells and rats, then we constructed hypoxia reoxygenation (H/R) cells and I/R rat model. Apoptosis, ROS, ATP, Ca2+ levels in cells and rats, as well as renal tissue and functional injury in rats were detected respectively. Endoplasmic reticulum (ER) stress was further examined in cells and rats. The morphological changes of mitochondria-associated ER membranes (MAMs) were also detected. Mfn2 expression is reduced in H/R-treated NRK-52E cells and renal tissue of I/R rats. At the cellular level, overexpression of Mfn2 promoted cell proliferation, inhibited cell apoptosis, attenuated mitochondrial damage and Ca2+ overload, and ER stress. In addition, Mfn2 also restored the MAMs structure. In vivo experiments found that overexpression of Mfn2 could improve renal function and alleviate tissue injury. Concomitant with elevated Mfn2 expression in the kidney, reduced renal cell apoptosis, restored mitochondrial function, and reduced calcium overload. Finally, ER stress in rat kidney tissue was alleviated after overexpression of Mfn2. These results reveal that Mfn2 contributes to ER stress, mitochondrial function, and cell death in I/R injury, which provides a novel therapeutic target for AKI.

Automated summary

This study demonstrates that Mfn2 plays a protective role in renal ischemia/reperfusion (I/R) injury. Overexpression of Mfn2 promotes cell proliferation, inhibits cell apoptosis, attenuates mitochondrial damage and calcium overload. Additionally, Mfn2 restores the structure of mitochondria-associated ER membranes (MAMs). In vivo experiments show that overexpression of Mfn2 improves renal function, alleviates tissue injury, reduces renal cell apoptosis, and calcium overload. Finally, overexpression of Mfn2 alleviates ER stress in renal tissue.