VDAC1 Cleavage Promotes Autophagy in Renal Tubular Epithelial Cells With Hypoxia/Reoxygenation Injury.

Aim: To study the effect and elucidate the underlying mechanisms of VDAC1-ΔC on autophagy in renal tubular epithelial cells injured by hypoxia/reoxygenation.

Methods: C57/BL6 mice were randomly divided into groups: sham operation group, IRI 1d group and IRI 2d group. The inner canthal blood of mice was collected to detect the levels of serum creatinine and urea nitrogen and kidney tissues were sampled, and sections were stained with Periodic acid-Schiff for morphological evaluation. The expression of VDAC1 in kidney tissue was detected by Western blot. An immortalised human proximal tubular epithelial cell line, HK-2 cells, were subjected to hypoxia/reoxygenation treatment. HK-2 cells were incubated under hypoxia for 6 h, followed by 6 and 24 h of reoxygenation, cells were divided into four groups: H6/R0 group, H6/R6 group, H6/R24 group and control group. The release of LDH and cytosolic ROS were assessed, the expression of autophagy-related proteins LC3 and p62 was detected by Western blot, autophagy flux was monitored by transfecting mRFP-GFP-LC3 lentivirus in HK2 cells, and cells were pretreated with bafilomycin A1 to further monitor the autophagy flux. VDAC1-cleavage-defective mutant in HK-2 cells silencing VDAC1 was established to examine the effect of VDAC1 cleavage on autophagy and hypoxia/reoxygenation injury.

Results: In vivo, IRI 1d/2d promoted the disorder of renal tubular structure and the cleavage of VDAC1 in kidney tissue; in vitro, hypoxia/reoxygenation promoted cytosolic ROS accumulation, LDH release, VDAC1 cleavage and induced autophagy and autophagic flux; reduced VDAC1 cleavage inhibited autophagy; and decreased cytosolic ROS accumulation and LDH release, thus alleviated cell injury.

Conclusion: In renal tubular epithelial cells injured by H/R, VDAC1 cleavage was increased, triggering an autophagic response, and VDAC1 cleavage promoted autophagy to regulate cell injury.