Diabetes Aggravates Renal Ischemia Reperfusion Injury by Repressing Mitochondrial Function and PINK1/Parkin-Mediated Mitophagy

OBJECTIVES:

Diabetes could aggravate ischemia/reperfusion (I/R) injury, but the underlying mechanism is unclear. In this study, we aimed to investigate whether diabetes exacerbates renal I/R injury and its possible mechanism.

MATERIALS AND METHODS:

In vitro, HK-2 cells in the normal or high glucose (HG) condition were subjected to hypoxia 12h followed by reoxygenation 3h. The cell viability, intracellular adenosine triphosphate (ATP) content, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) production and apoptosis were performed. In vivo, streptozotocin-induced diabetic and non-diabetic rats were subjected with I/R. Renal pathology, function, and apoptosis were evaluated by hematoxylin-eosin staining, transmission electron microscope (TEM) and western blot.

RESULTS:

Compared with normal glucose with hypoxia/reoxygenation (NH/R) group, mitochondrial function (ATP, MMP, ROS) and mitophagy were reduced in high glucose with H/R(HG+H/R), as well as expression of PINK1 and Parkin. Also, cells in HG+H/R group exhibited more apoptosis when compared with NH/R group through flow cytometry, TUNEL staining and Western blot. Compared with normal rats underwent I/R(NI/R), diabetic rats undergoing I/R(DI/R) exhibited more severe tubular damage and renal dysfunction, as well as expression of apoptotic protein Caspase-3. Meanwhile, diabetes alleviated mitophagy associated protein expression in rats subjected with I/R, including PINK1 and Parkin. TEM indicated that mitophagosome could be hardly observed and mitochondria morphology and structure were obviously damaged in DI/R group.

CONCLUSION:

Our results, for the first time, indicated that diabetes could aggravate I/R injury by repressing mitochondrial function and PINK1/Parkin-mediated mitophagy in vivo and in vitro.