Involvement of phosphatase and tensin homolog-induced putative kinase 1–Parkin-mediated mitophagy in septic acute kidney injury

Abstract

Background:Studies have reported mitophagy activation in renal tubular epithelial cells (RTECs) in acute kidney injury (AKI). Phosphatase and tensin homolog-induced putative kinase 1 (PINK1) and E3 ubiquitin-protein ligase Parkin are involved in mitophagy regulation; however, little is known about the role of PINK1-Parkin mitophagy in septic AKI. Here we investigated whether the PINK1-Parkin mitophagy pathway is involved in septic AKI and its effects on cell apoptosis in vitro and on renal functions in vivo.Methods:Mitophagy-related gene expression was determined using Western blot assay in human RTEC cell line HK-2 stimulated with bacterial lipopolysaccharide (LPS) and in RTECs from septic AKI rats induced by cecal ligation and perforation (CLP). Autophagy-related ultrastructural features in rat RTECs were observed using electron microscopy. Gain- and loss-of-function approaches were performed to investigate the role of the PINK1-Parkin pathway in HK-2 cell mitophagy. Autophagy activators and inhibitors were used to assess the effects of mitophagy modulation on cell apoptosis in vitro and on renal functions in vivo.Results:LPS stimulation could significantly induce LC3-II and BECN-1 protein expression (LC3-II: 1.72 ± 0.05 vs. 1.00 ± 0.05, P < 0.05; BECN-1: 5.33 ± 0.57 vs. 1.00 ± 0.14, P < 0.05) at 4 h in vitro. Similarly, LC3-II, and BECN-1 protein levels were significantly increased and peaked at 2 h after CLP (LC3-II: 3.33 ± 0.12 vs. 1.03 ± 0.15, P < 0.05; BECN-1: 1.57 ± 0.26 vs. 1.02 ± 0.11, P < 0.05) in vivo compared with those after sham operation. Mitochondrial deformation and mitolysosome-mediated mitochondria clearance were observed in RTECs from septic rats. PINK1 knockdown significantly attenuated LC3-II protein expression (1.35 ± 0.21 vs. 2.38 ± 0.22, P < 0.05), whereas PINK1 overexpression markedly enhanced LC3-II protein expression (2.07 ± 0.21 vs. 1.29 ± 0.19, P < 0.05) compared with LPS-stimulated HK-2 cells. LPS-induced proapoptotic protein expression remained unchanged in autophagy activator-treated HK-2 cells and was significantly attenuated in PINK1-overexpressing cells, but was remarkably upregulated in autophagy inhibitor-treated and in PINK1-depleted cells. Consistent results were observed in flow cytometric apoptosis assay and in renal function indicators in rats.Conclusion:PINK1-Parkin-mediated mitophagy might play a protective role in septic AKI, serving as a potential therapeutic target for septic AKI.

Role of Parkin-mediated mitophagy in the protective effect of polydatin in sepsis-induced acute kidney injury

“…These findings indicate that PD treatment alleviates SI-AKI by upregulating Parkin-dependent mitophagy. Our results are consistent with a previous study showing that Parkin-mediated mitophagy plays a protective role in septic AKI [28].…”

LncRNA SNHG14 promotes OGD/R-induced neuron injury by inducing excessive mitophagy via miR-182-5p/BINP3 axis in HT22 mouse hippocampal neuronal cells

“…f The expression of BNIP3, caspase-3, cleaved-caspase-3, caspase-9 and cleaved-caspase-9 in the modified HT22 cells was examined by WB. (*P < 0.05, **P < 0.01, versus mimic NC + Vector or Vector + si-Ctrl; # P < 0.05, ## P < 0.01, versus Vector + miR-182-5p mimic Vector + si-BNIP3) mitophagy has a crucial role in various diseases, such as CI/R injury [20], Parkinson's disease and septic acute kidney injury [21,22]. However, SNHG14 overexpression or knockdown had no effect on the expression of PINK1 and Parkin, suggesting that SNHG14 can not regulate mitophagy by activating PINK1/Parkin signaling pathway.…”

“…The PINK1/Parkin signaling pathway is the most typical signaling pathway that regulates mitophagy. PINK1/Parkin-mediated mitophagy has a crucial role in various diseases, such as CI/R injury [ 20 ], Parkinson’s disease and septic acute kidney injury [ 21 , 22 ]. However, SNHG14 overexpression or knockdown had no effect on the expression of PINK1 and Parkin, suggesting that SNHG14 can not regulate mitophagy by activating PINK1/Parkin signaling pathway.…”

Mitophagy in Acute Kidney Injury and Kidney Repair

“…Using Pink1 or Park2 deficient mice, we provided evidence that PINK1 and PARK2-dependent mitophagy was protective against kidney injury during cisplatin nephrotoxicity [114]. In contrast, a recent study by Zhou et al showed that PINK1 deficiency ameliorated cisplatin-induced mitochondrial fragmentation, mitophagy, and kidney injury in rats [115]. The cause of the discrepancy between these studies remains unknown.…”

“…Emerging evidence also suggests a potential role of BNIP3 in regulating mitophagy in cisplatin-induced AKI. Upregulation of BNIP3 was noticed in renal tubules of rats exposed to cisplatin [115]. Liang et al showed panax notoginseng saponins enhanced mitophagy via a HIF-1α/BNIP3/BENCI signaling pathway to protect against cisplatin-induced nephrotoxicity [116].…”