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. 2019 Sep 6:17:701-713.
doi: 10.1016/j.omtn.2019.06.025. Epub 2019 Jul 12.

Necrostatin-1 Attenuates Renal Ischemia and Reperfusion Injury via Meditation of HIF-1α/mir-26a/TRPC6/PARP1 Signaling

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Necrostatin-1 Attenuates Renal Ischemia and Reperfusion Injury via Meditation of HIF-1α/mir-26a/TRPC6/PARP1 Signaling

Bingbing Shen et al. Mol Ther Nucleic Acids. .

Abstract

Necroptosis, oxidative stress, and inflammation are major contributors to the pathogenesis of ischemic acute kidney injury. Necrostatin-1 (Nec-1), an inhibitor of the kinase domain of receptor-interacting protein kinase-1 (RIP1), has been reported to regulate renal ischemia and reperfusion (I/R) injury; however, its underlying mechanism of action remains unclear. HK-2 cells were used to create an in vitro I/R model, in which the cells were subjected to hypoxia, followed by 2, 6, and 12 h of reoxygenation. For the in vivo study, a rat model of renal I/R was established in which samples of rat blood serum and kidney tissue were harvested after reperfusion to assess renal function and detect histological changes. Cell viability and necroptosis were analyzed using the Cell Counting Kit (CCK)-8 assay and flow cytometry, respectively. The expression levels of molecules associated with necroptosis, oxidative stress, and inflammation were determined by real-time PCR, western blotting, immunofluorescence staining, and ELISA. Luciferase and chromatin immunoprecipitation (ChIP) assays were performed to confirm the relevant downstream signaling pathway. We found that pretreatment with Nec-1 significantly decreased hypoxia-inducible factor-1α (HIF-1α) and miR-26a expression, as well as the levels of factors associated with necroptosis (RIP1, RIP3, and Sirtuin-2), oxidative stress (malondialdehyde [MDA], NADP+/NADPH ratio), and inflammation (interleukin [IL]-1β, IL-10, and tumor necrosis factor alpha [TNF-α]) in I/R injury cells and the rat model. However, these effects could be reversed by miR-26a overexpression or TRPC6 knockdown. Mechanistic studies demonstrated that HIF-1α directly binds to the promoter region of miR-26a, and that TRPC6 is a potential target gene for miR-26a. Our findings indicate that Nec-1 can effectively protect against renal I/R injury by inhibiting necroptosis, oxidative stress, and inflammation, and may exert its effects through mediation of the HIF-1α/miR-26a/TRPC6/PARP1 signaling pathway.

Keywords: HIF-1α; Nec-1; TRPC6; inflammation; ischemic/reperfusion injury; miR-26a; necroptosis; oxidative stress.

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Figures

Figure 1
Figure 1
Effects of Nec-1 Treatment on HK-2 Cell Viability and Necrosis under Conditions of H/R Injury (A) Cell viability was assessed using the CCK-8 assay. (B) Cells were stained with Annexin V-FITC (x axis) and PI (y axis), and analyzed by flow cytometry. (C) Statistical analysis of the percentage of necrotic cells (Annexin V/PI+). *p < 0.05 versus the control group; #p < 0.05 versus the H/R injury group.
Figure 2
Figure 2
The Levels of HIF-1α, miR-26a, TRPC6, Necroptosis, Oxidative Stress, and Inflammation-Related Molecules in HK-2 Cells under Conditions of H/R Injury with or without Nec-1 Treatment (A) Western blotting was performed to detect HIF-1α, RIP1, RIP3, TRPC6, PARP1, and Sirtuin-2 expression in HK-2 cells. (B) An MDA detection kit and NADP+/NADPH assay kit were used to measure the MDA level and NADP+/NADPH ratio, respectively. Specific ELISA kits were used to detect the levels of inflammatory cytokines, IL-1β, IL-10, and TNF-α. *p < 0.05 versus control group; #p < 0.05 versus the H/R injury group.
Figure 3
Figure 3
Effects of Downregulation or Upregulation of miR-26a on the Viability and Necrosis of HK-2 Cells under Conditions of H/R Injury with or without Nec-1 Treatment (A) Cell viability was assessed using the CCK-8 assay. (B) Cells were stained with Annexin V-FITC (x axis) and PI (y axis), and analyzed by flow cytometry. (C) Statistical analysis of the percentage of necrotic cells (Annexin V/PI+). *p < 0.05, **p < 0.01 versus the NC group; #p < 0.05, ##p < 0.01 versus the Nec-1 + H/R group.
Figure 4
Figure 4
Effects of Downregulation or Upregulation of miR-26a on the Levels of HIF-1α, miR-26a, and TRPC6 Expression, Necroptosis, Oxidative Stress, and Inflammation-Related Molecules in HK-2 Cells under Conditions of H/R Injury with or without Nec-1 Treatment (A) Western blotting was performed to detect HIF-1α, RIP1, RIP3, TRPC6, PARP1, and Sirtuin-2 expression in HK-2 cells. (B) Immunofluorescence images showing RIP3, HIF-1α, and TRPC6 expression, respectively. (C) An MDA detection kit and NADP+/NADPH assay kit were used to measure the MDA level and NADP+/NADPH ratio, respectively. Specific ELISA kits were used to detect the levels of inflammatory cytokines, IL-1β, IL-10, and TNF-α. *p < 0.05, **p < 0.01 versus the NC group; #p < 0.05, ##p < 0.01 versus the Nec-1 + H/R group.
Figure 5
Figure 5
Effects of TRPC6 Overexpression or Knockdown on the Viability and Necrosis of HK-2 Cells under Conditions of H/R Injury with or without Nec-1 Treatment (A) Cell viability was assessed using the CCK-8 assay. (B) Cells were stained with Annexin V-FITC (x axis) and PI (y axis), and analyzed by flow cytometry. (C) Statistical analysis of the percentage of necrotic cells (Annexin V/PI+). *p < 0.05, compared with the siNC group; #p < 0.05 versus the pcDNA3.1 group; &p < 0.05 versus the Nec-1 + siTRPC6 group; @p < 0.05 versus the Nec-1 + pcDNA3.1 group.
Figure 6
Figure 6
Effects of TRPC6 Overexpression or Knockdown on the Levels HIF-1α, miR-26a, TRPC6, Necroptosis, Oxidative Stress, and Inflammation-Related Molecules in HK-2 Cells under Conditions of H/R Injury with or without Nec-1 Treatment (A) Western blotting was performed to detect HIF-1α, RIP1, RIP3, TRPC6, PARP1, and Sirtuin-2 expression in HK-2 cells. (B) Immunofluorescence images showing RIP3, TRPC6, PARP1, and Sirtuin-2 expression, respectively. (C) An MDA detection kit and NADP+/NADPH assay kit were used to measure the MDA level and NADP+/NADPH ratio, respectively. Specific ELISA kits were used to detect the levels of inflammatory cytokines, IL-1β, IL-10, and TNF-α. *p < 0.05 versus the siNC group; #p < 0.05 versus the pcDNA3.1 group; &p < 0.05 versus the Nec-1 + siTRPC6 group; @p < 0.05 versus the Nec-1 + pcDNA3.1 group.
Figure 7
Figure 7
HIF-1α/miR-26a/TRPC6 Signaling Was Involved in the Protective Role of Nec-1 in HK-2 Cells under Conditions of H/R Injury (A) The five regions of HIF-1α that bound with miR-26a are shown. MiR-26a was identified as a target gene of HIF-1α in HK-2 cells. Five wild-type (WT) or the corresponding six mutant miR-26a 3′ UTRs were co-transfected with pcDNA-HIF-1α or pcDNA-Vector into HK-2 cells; luciferase activity was measured by the dual-luciferase reporter assay. ***p < 0.001, compared with the pcDNA-Vector; ***p < 0.001, compared with the pcDNA-Vector. (B) ChIP assays revealed that HIF-1α directly bound to the promoter region of miR-26a and enhanced the promoter’s activity. (C) Real-time PCR analysis of miR-26a expression. **p < 0.001, compared with input. (D) Sequences of the TRPC6 3′ UTR and miR-26a as predicted by bioinformatics databases (Targetscan, PicTar, and miRanda). (E) Luciferase activity was measured by the dual-luciferase reporter assay. ***p < 0.001 versus NC mimics.
Figure 8
Figure 8
Nec-1 Pretreatment Protected Rat Kidney Tissue against I/R-Induced Oxidative Stress and Inflammation via the HIF-1α/miR-26a/TRPC6 Pathway Rats in the I/R group were divided into five sub-groups according to whether OAG (Sigma, USA), SKF96365 (Sigma, USA), or veliparib (Selleck) was administered before the I/R procedure at 6 h. Similarly, rats in the I/R + Nec-1 group were also divided into three sub-groups. (A) Western blotting was performed to detect HIF-1α, RIP1, RIP3, TRPC6, PARP1, and Sirtuin-2 expression in renal tissues. (B) An MDA detection kit and NADP+/NADPH assay kit were used to measure the MDA level and NADP+/NADPH ratio, respectively. Specific ELISA kits were used to detect the levels of inflammatory cytokines, IL-1β, IL-10, and TNF-α. *p < 0.05 versus the control group; #p < 0.05 versus the I/R group; &p < 0.05 versus the I/R + Nec-1 group; @p < 0.05 versus the I/R + OAG group.
Figure 9
Figure 9
Effect of Nec-1 Pretreatment on Renal Histopathological Changes and Immunohistochemical Analysis Results in a Rat Model of Renal I/R Rats in the I/R group were divided into five sub-groups according to whether OAG (Sigma, USA), SKF96365 (Sigma, USA), or veliparib (Selleck) was administered before the I/R procedure. Similarly, rats in I/R + Nec-1 group were also divided into three sub-groups. (A) Sections of kidney tissue were stained with H&E and subjected to histological examination to detect renal tubule injuries. (B) Immunohistochemical analysis of RIP1, RIP3, TRPC6, and PARP1 in renal tissues. *p < 0.05 versus the control group; #p < 0.05 versus the I/R group; &p < 0.05 versus the I/R + Nec-1 group; @p < 0.05 versus the I/R + OAG group.

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