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HIF-1? ameliorates tubular injury in diabetic nephropathy via HO-1-mediated control of mitochondrial dynamics.

ABSTRACT: OBJECTIVES:In diabetic nephropathy (DN), hypoxia-inducible factor-1? (HIF-1?) activation in tubular cells plays an important protective role against kidney injury. The effects may occur via the target genes of HIF-1?, such as haem oxygenase-1 (HO-1), but the exact mechanisms are incompletely understood. MATERIALS AND METHODS:Mice with proximal tubule-specific knockout of HIF-1? (PT-HIF-1?-/- mice) were generated, and diabetes was induced in these mice by streptozotocin (STZ) injection. In addition, to mimic a hypoxic state, cobaltous chloride (CoCl2 ) was applied to HK-2 cells. RESULTS:Our study first verified that conditional knockout of HIF-1? worsened tubular injury in DN; additionally, aggravated kidney dysfunction, renal histopathological alterations, mitochondrial fragmentation, ROS accumulation and apoptosis were observed in diabetic PT-HIF-1?-/- mice. In vitro study showed that compared to control group, HK-2 cells cultured under hypoxic ambiance displayed increased mitochondrial fragmentation, ROS production, mitochondrial membrane potential loss and apoptosis. These increases were reversed by overexpression of HIF-1? or treatment with a HO-1 agonist. Importantly, cotreatment with a HIF-1? inhibitor and a HO-1 agonist rescued the HK-2 cells from the negative impacts of the HIF-1? inhibitor. CONCLUSIONS:These data revealed that HIF-1? exerted a protective effect against tubular injury in DN, which could be mediated via modulation of mitochondrial dynamics through HO-1 upregulation.

SUBMITTER: Jiang N

PROVIDER: S-EPMC7653251 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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HIF-1α ameliorates tubular injury in diabetic nephropathy via HO-1-mediated control of mitochondrial dynamics.

Jiang Na N Zhao Hao H Han Yachun Y Li Li L Xiong Shan S Zeng Lingfeng L Xiao Ying Y Wei Ling L Xiong Xiaofen X Gao Peng P Yang Ming M Liu Yu Y Sun Lin L

Cell proliferation 20200925 11

<h4>Objectives</h4>In diabetic nephropathy (DN), hypoxia-inducible factor-1α (HIF-1α) activation in tubular cells plays an important protective role against kidney injury. The effects may occur via the target genes of HIF-1α, such as haem oxygenase-1 (HO-1), but the exact mechanisms are incompletely understood.<h4>Materials and methods</h4>Mice with proximal tubule-specific knockout of HIF-1α (PT-HIF-1α<sup>-/-</sup> mice) were generated, and diabetes was induced in these mice by streptozotocin ...[more]

PMID: 32975326

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Project description:BackgroundDiabetic nephropathy (DN) represents a major complication of diabetes, and podocyte injury has a critical function in DN development. TangShenWeiNing formula (TSWN) has been demonstrated to efficiently decrease proteinuria and protect podocytes in DN. This work aimed to explore the mechanism by which TSWN alleviates DN and protects podocytes.MethodsThe major bioactive components of TSWN were detected by mass spectrometry (MS) and pharmacological databases. Eight-week-old male C57BLKS/J db/m and db/db mice were provided pure water, valsartan, low dose TSWN, middle dose TSWN and high dose TSWN by gavage for 12 weeks, respectively.ResultsMS and network pharmacology analyses suggested that TSWN might prevent DN through the sirtuin (SIRT)1/hypoxia-inducible factor (HIF)-1α pathway. Diabetic mice showed elevated urinary albumin in comparison with non-diabetic mice, and TSWN decreased urinary albumin in diabetic mice. Histological injury increased in the kidney in diabetic mice, which could be improved by TSWN. Fibrosis and collagen I expression were induced in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney; TSWN alleviated these effects. Apoptosis and cleaved caspase-3 were induced in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney, and TSWN blunted these effects. Podocytes were damaged in the diabetic mouse kidney, which was improved by TSWN. Podocin and nephrin amounts were decreased in the diabetic mouse kidney in comparison with the non-diabetic mouse kidney, and podocalyxin was increased in urine of diabetic animals in comparison with non-diabetic counterparts. After TSWN treatment, podocin and nephrin were raised in the diabetic mouse kidney, and urinary podocalyxin was depressed in diabetic animals. Diabetic mice had lower SIRT1 and higher HIF-1α amounts in kidney specimens in comparison with non-diabetic mice, and TSWN promoted SIRT1 and inhibited HIF-1α in the diabetic mouse kidney. Moreover, co-staining of SIRT1 and podocin revealed that SIRT1 decreased in podocytes from diabetic mice in comparison with those from non-diabetic mice, and TSWN elevated SIRT1 in podocytes.ConclusionsThis study indicated that TSWN alleviates DN by improving podocyte injury through the SIRT1/HIF-1α pathway in diabetic mouse kidneys.

Project description:Background Albuminuria is a hallmark of diabetic kidney disease (DKD) that promotes its progression, leading to renal fibrosis. Renal macrophage function is complex and influenced by macrophage metabolic status. However, the metabolic state of diabetic renal macrophages and the impact of albuminuria on the macrophage metabolic state are poorly understood. Methods Extracellular vesicles (EVs) from tubular epithelial cells (HK-2) were evaluated using transmission electron microscopy, nanoparticle tracking analysis and western blotting. Glycolytic enzyme expression in macrophages co-cultured with HSA-treated HK-2 cell-derived EVs was detected using RT-qPCR and western blotting. The potential role of EV-associated HIF-1α in the mediation of glycolysis was explored in HIF-1α siRNA pre-transfected macrophages co-cultured with HSA-treated HK-2 cell-derived EVs, and the extent of HIF-1α hydroxylation was measured using western blotting. Additionally, we injected db/db mice with EVs via the caudal vein twice a week for 4 weeks. Renal macrophages were isolated using CD11b microbeads, and immunohistofluorescence was applied to confirm the levels of glycolytic enzymes and HIF-1α in these macrophages. Results Glycolysis was activated in diabetic renal macrophages after co-culture with HSA-treated HK-2 cells. Moreover, HSA-treated HK-2 cell-derived EVs promoted macrophage glycolysis both in vivo and in vitro. Inhibition of glycolysis activation in macrophages using the glycolysis inhibitor 2-DG decreased the expression of both inflammatory and fibrotic genes. Mechanistically, EVs from HSA-stimulated HK-2 cells were found to accelerate macrophage glycolysis by stabilizing HIF-1α. We also found that several miRNAs and lncRNAs, which have been reported to stabilize HIF-1α expression, were increased in HSA-treated HK-2 cell-derived EVs. Conclusion Our study suggested that albuminuria induced renal macrophage glycolysis through tubular epithelial cell-derived EVs by stabilizing HIF-1α, indicating that regulation of macrophage glycolysis may offer a new treatment strategy for DKD patients, especially those with macroalbuminuria. Supplementary Information The online version contains supplementary material available at 10.1186/s10020-022-00525-1.

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HIF-1? ameliorates tubular injury in diabetic nephropathy via HO-1-mediated control of mitochondrial dynamics.

Publications

HIF-1α ameliorates tubular injury in diabetic nephropathy via HO-1-mediated control of mitochondrial dynamics.

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