The Loss of Mitochondrial Quality Control in Diabetic Kidney Disease

Mitochondrial dysfunction in acute kidney injury

Acute kidney injury (AKI) is a systemic clinical syndrome increasing morbidity and mortality worldwide in recent years. Renal tubular epithelial cells (TECs) death caused by mitochondrial dysfunction is one of the pathogeneses. The imbalance of mitochondrial quality control is the main cause of mitochondrial dysfunction. Mitochondrial quality control plays a crucial role in AKI. Mitochondrial quality control mechanisms are involved in regulating mitochondrial integrity and function, including antioxidant defense, mitochondrial quality control, mitochondrial DNA (mtDNA) repair, mitochondrial dynamics, mitophagy, and mitochondrial biogenesis. Currently, many studies have used mitochondrial dysfunction as a targeted therapeutic strategy for AKI. Therefore, this review aims to present the latest research advancements on mitochondrial dysfunction in AKI, providing a valuable reference and theoretical foundation for clinical prevention and treatment of this condition, ultimately enhancing patient prognosis.

JinChan YiShen TongLuo Formula ameliorate mitochondrial dysfunction and apoptosis in diabetic nephropathy through the HIF-1α-PINK1-Parkin pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The JinChan YiShen TongLuo (JCYSTL) formula, a traditional Chinese medicine (TCM), has been used clinically for decades to treat diabetic nephropathy (DN). TCM believes that the core pathogenesis of DN is "kidney deficiency and collateral obstruction," and JCYSTL has the effect of "tonifying kidney and clearing collateral," thus alleviating the damage to kidney structure and function caused by diabetes. From the perspective of modern medicine, mitochondrial damage is an important factor in DN pathogenesis. Our study suggests that the regulation of mitophagy and mitochondrial function by JCYSTL may be one of the internal mechanisms underlying its good clinical efficacy.

AIM OF THE STUDY

This study aimed to investigate the mechanisms underlying the renoprotective effects of JCYSTL.

MATERIALS AND METHODS

Unilateral nephrectomy combined with low-dose streptozotocin intraperitoneally injected in a DN rat model and high glucose (HG) plus hypoxia-induced HK-2 cells were used to explore the effects of JCYSTL on the HIF-1α/mitophagy pathway, mitochondrial function and apoptosis.

RESULTS

JCYSTL treatment significantly decreased albuminuria, serum creatinine, blood urea nitrogen, and uric acid levels and increased creatinine clearance levels in DN rats. In vitro, medicated serum containing JCYSTL formula increased mitochondrial membrane potential (MMP); improved activities of mitochondrial respiratory chain complexes I, III, and IV; decreased the apoptotic cell percentage and apoptotic protein Bax expression; and increased anti-apoptotic protein Bcl-2 expression in HG/hypoxia-induced HK-2 cells. The treatment group exhibited increased accumulation of PINK1, Parkin, and LC3-II and reduced P62 levels in HG/hypoxia-induced HK-2 cells, whereas in PINK1 knockdown HK-2 cells, JCYSTL did not improve the HG/hypoxia-induced changes in Parkin, LC3-II, and P62. When mitophagy was impaired by PINK1 knockdown, the inhibitory effect of JCYSTL on Bax and its promoting effect on MMP and Bcl-2 disappeared. The JCYSTL-treated group displayed significantly higher HIF-1α expression than the model group in vivo, which was comparable to the effects of FG-4592 in DN rats. PINK1 knockdown did not affect HIF-1α accumulation in JCYSTL-treated HK-2 cells exposed to HG/hypoxia. Both JCYSTL and FG-4592 ameliorated mitochondrial morphological abnormalities and reduced the mitochondrial respiratory chain complex activity in the renal tubules of DN rats. Mitochondrial apoptosis signals in DN rats, such as increased Bax and Caspase-3 expression and apoptosis ratio, were weakened by JCYSTL or FG-4592 administration.

CONCLUSION

This study demonstrates that the JCYSTL formula activates PINK1/Parkin-mediated mitophagy by stabilizing HIF-1α to protect renal tubules from mitochondrial dysfunction and apoptosis in diabetic conditions, presenting a promising therapy for the treatment of DN.

The role of mitochondrial dysfunction in kidney injury and disease

Mitochondria are the main sites of aerobic respiration in the cell and mainly provide energy for the organism, and play key roles in adenosine triphosphate (ATP) synthesis, metabolic regulation, and cell differentiation and death. Mitochondrial dysfunction has been identified as a contributing factor to a variety of diseases. The kidney is rich in mitochondria to meet energy needs, and stable mitochondrial structure and function are essential for normal kidney function. Recently, many studies have shown a link between mitochondrial dysfunction and kidney disease, maintaining mitochondrial homeostasis has become an important target for kidney therapy. In this review, we integrate the role of mitochondrial dysfunction in different kidney diseases, and specifically elaborate the mechanism of mitochondrial reactive oxygen species (mtROS), autophagy and ferroptosis involved in the occurrence and development of kidney diseases, providing insights for improved treatment of kidney diseases.

Renal aging and mitochondrial quality control

Mitochondria are dynamic organelles that participate in different cellular process that control metabolism, cell division, and survival, and the kidney is one of the most metabolically active organs that contains abundant mitochondria. Perturbations in mitochondrial homeostasis in the kidney can accelerate kidney aging, and maintaining mitochondrial homeostasis can effectively delay aging in the kidney. Kidney aging is a degenerative process linked to detrimental processes. The significance of aberrant mitochondrial homeostasis in renal aging has received increasing attention. However, the contribution of mitochondrial quality control (MQC) to renal aging has not been reviewed in detail. Here, we generalize the current factors contributing to renal aging, review the alterations in MQC during renal injury and aging, and analyze the relationship between mitochondria and intrinsic renal cells. We also introduce MQC in the context of renal aging, and discuss the study of mitochondria in the intrinsic cells of the kidney, which is the innovation of our paper. In addition, during kidney injury and repair, the specific functions and regulatory mechanisms of MQC systems in resident and circulating cell types remain unclear. Currently, most of the studies we reviewed are based on animal and cellular models, the relationship between renal tissue aging and mitochondria has not been adequately investigated in clinical studies, and there is still a long way to go.

Targeted drug delivery strategy: a bridge to the therapy of diabetic kidney disease

Diabetic kidney disease (DKD) is the main complication in diabetes mellitus (DM) and the main cause of end-stage kidney disease worldwide. However, sodium glucose cotransporter 2 (SGLT2) inhibition, glucagon-like peptide-1 (GLP-1) receptor agonist, mineralocorticoid receptor antagonists and endothelin receptor A inhibition have yielded promising effects in DKD, a great part of patients inevitably continue to progress to uremia. Newly effective therapeutic options are urgently needed to postpone DKD progression. Recently, accumulating evidence suggests that targeted drug delivery strategies, such as macromolecular carriers, nanoparticles, liposomes and so on, can enhance the drug efficacy and reduce the undesired side effects, which will be a milestone treatment in the management of DKD. The aim of this article is to summarize the current knowledge of targeted drug delivery strategies and select the optimal renal targeting strategy to provide new therapies for DKD.

The emerging role of microplastics in systemic toxicity: Involvement of reactive oxygen species (ROS)

Plastic pollution is one of the most pressing environmental threats the world is facing currently. The degradation of macroplastics into smaller forms viz. microplastics (MPs) or Nanoplastics (NPs) is a potential threat to both terrestrial and marine ecosystems and also to human health by directly affecting the organs and activating a plethora of intracellular signaling, that may lead to cell death. There is accumulating evidence that supports the serious toxicity caused by MP/NPs at all levels of biological complexities (biomolecules, organelles, cells, tissues, organs, and organ systems) and the involvement of the reactive oxygen species (ROS) in this process. Studies indicate that MPs or NPs can accumulate in mitochondria and further disrupt the mitochondrial electron transport chain, cause mitochondrial membrane damage, and perturb the mitochondrial membrane potential or depolarization of the mitochondria. These events eventually lead to the generation of different types of reactive free radicals, which can induce DNA damage, protein oxidation, lipid peroxidation, and compromization of the antioxidant defense pool. Furthermore, MP-induced ROS was found to trigger a plethora of signaling cascades, such as the p53 signaling pathway, Mitogen-activated protein kinases (MAPKs) signaling pathway including the c-Jun N-terminal kinases (JNK), p38 kinase, and extracellular signal related kinases (ERK1/2) signaling cascades, Nuclear factor erythroid 2-related factor 2 (Nrf2)-pathway, Phosphatidylinositol-3-kinases (PI3Ks)/Akt signaling pathway, and Transforming growth factor-beta (TGF-β) pathways, to name a few. As a consequence of oxidative stress caused by the MPs/NPs, different types of organ damage are observed in living species, including humans, such as pulmonary toxicity, cardiotoxicity, neurotoxicity, nephrotoxicity, immunotoxicity, reproductive toxicity, hepatotoxicity, etc. Although presently, a good amount of research is going on to access the detrimental effects of MPs/NPs on human health, there is a lack of proper model systems, multi-omics approaches, interdisciplinary research, and mitigation strategies.

Mitochondrial quality control and its emerging role in the pathogenesis of diabetic kidney disease

Most eukaryotic cells have mitochondrial networks that can change in shape, distribution, and size depending on cellular metabolic demands and environments. Mitochondrial quality control is critical for various mitochondrial functions including energy production, redox homeostasis, intracellular calcium handling, cell differentiation, proliferation, and cell death. Quality control mechanisms within mitochondria consist of antioxidant defenses, protein quality control, DNA damage repair systems, mitochondrial fusion and fission, mitophagy, and mitochondrial biogenesis. Defects in mitochondrial quality control and disruption of mitochondrial homeostasis are common characteristics of various kidney cell types under hyperglycemic conditions. Such defects contribute to diabetes-induced pathologies in renal tubular cells, podocytes, endothelial cells, and immune cells. In this review, we focus on the roles of mitochondrial quality control in diabetic kidney disease pathogenesis and discuss current research evidence and future directions.

Pharmacological and Genetic Suppression of VDAC1 Alleviates the Development of Mitochondrial Dysfunction in Endothelial and Fibroblast Cell Cultures upon Hyperglycemic Conditions

Prolonged hyperglycemia related to diabetes and its complications leads to multiple cellular disorders, the central one being the dysfunction of mitochondria. Voltage-dependent anion channels (VDAC) of the outer mitochondrial membrane control the metabolic, ionic, and energy cross-talk between mitochondria and the rest of the cell and serve as the master regulators of mitochondrial functions. Here, we have investigated the effect of pharmacological suppression of VDAC1 by the newly developed inhibitor of its oligomerization, VBIT-4, in the primary culture of mouse lung endotheliocytes and downregulated expression of VDAC1 in human skin fibroblasts on the progression of mitochondrial dysfunction upon hyperglycemic stress. The cells were grown in high-glucose media (30 mM) for 36 h. In response to hyperglycemia, the mRNA level of VDAC1 increased in endotheliocytes and decreased in human skin fibroblasts. Hyperglycemia induced overproduction of mitochondrial ROS, an increase in the susceptibility of the organelles to mitochondrial permeability transition (MPT) pore opening and a drop in mitochondrial membrane potential, which was accompanied by a decrease in cell viability in both cultures. Treatment of endotheliocytes with 5 µM VBIT-4 abolished the hyperglycemia-induced increase in susceptibility to spontaneous opening of the MPT pore and ROS generation in mitochondria. Silencing of VDAC1 expression in human skin fibroblasts exposed to high glucose led to a less pronounced manifestation of all the signs of damage to mitochondria. Our data identify a mitochondria-related response to pharmacological and genetic suppression of VDAC activity in vascular cells in hyperglycemia and suggest the potential therapeutic value of targeting these channels for the treatment of diabetic vasculopathies.

Mitophagy, Inflammasomes and Their Interaction in Kidney Diseases: A Comprehensive Review of Experimental Studies

Mitophagy is an important mechanism for mitochondrial quality control by regulating autophagosome-specific phagocytosis, degradation and clearance of damaged mitochondria, and involved in cell damage and diseases. Inflammasomes are important inflammation-related factors newly discovered in recent years, which are involved in cell innate immunity and inflammatory response, and play an important role in kidney diseases. Based on the current studies, we reviewed the progress of mitophagy, inflammasomes and their interaction in kidney diseases.

Qing-Re-Xiao-Zheng-Yi-Qi formula relieves kidney damage and activates mitophagy in diabetic kidney disease

Introduction: Qing-Re-Xiao-Zheng-Yi-Qi Formula is an effective prescription in diabetic kidney disease treatment, we have confirmed the efficacy of Qing-Re-Xiao-Zheng therapy in diabetic kidney disease through clinical trials. In this study, we investigated the mechanisms of Qing-Re-Xiao-Zheng-Yi-Qi Formula in the treatment of diabetic kidney disease. Methods: We used Vanquish UHPLC^TM to analyze the chemical profiling of Qing-Re-Xiao-Zheng-Yi-Qi Formula freeze-dried powder. We constructed diabetic kidney disease rat models induced by unilateral nephrectomy and high-dose streptozocin injection. We examined blood urea nitrogen, serum creatinine, serum glucose, total cholesterol, triglyceride, serum total protein, albumin, alanine aminotransferase, aspartate aminotransferase and 24 h urinary total protein in diabetic kidney disease rats. The renal pathological changes were observed by HE, Masson, PAS stanning and transmission electron microscopy. The levels of fibrosis-related proteins and mitophagy-related proteins were detected by western blot analysis. We also conducted an immunofluorescence co-localization analysis on podocytes to further investigate the effect of Qing-Re-Xiao-Zheng-Yi-Qi Formula treatment on mitophagy. Results: A total of 27 constituents in Qing-Re-Xiao-Zheng-Yi-Qi Formula were tentatively identified. We found PINK1/Parkin-mediated mitophagy was inhibited in diabetic kidney disease. Qing-Re-Xiao-Zheng-Yi-Qi Formula treatment could raise body weight and reduce renal index, reduce proteinuria, improve glycolipid metabolic disorders, ameliorate renal fibrosis, and reduce the expression of Col Ⅳ and TGF-β1 in diabetic kidney disease rats. Qing-Re-Xiao-Zheng-Yi-Qi Formula treatment could also increase the expression of nephrin, activate mitophagy and protect podocytes in diabetic kidney disease rats and high glucose cultured podocytes. Conclusion: PINK1/Parkin-mediated mitophagy was inhibited in diabetic kidney disease, and Qing-Re-Xiao-Zheng-Yi-Qi Formula treatment could not only ameliorate pathological damage, but also promote mitophagy to protect podocytes in diabetic kidney disease.

Effect of Chronic Treatment with Uridine on Cardiac Mitochondrial Dysfunction in the C57BL/6 Mouse Model of High-Fat Diet-Streptozotocin-Induced Diabetes

Long-term hyperglycemia in diabetes mellitus is associated with complex damage to cardiomyocytes and the development of mitochondrial dysfunction in the myocardium. Uridine, a pyrimidine nucleoside, plays an important role in cellular metabolism and is used to improve cardiac function. Herein, the antidiabetic potential of uridine (30 mg/kg/day for 21 days, i.p.) and its effect on mitochondrial homeostasis in the heart tissue were examined in a high-fat diet-streptozotocin-induced model of diabetes in C57BL/6 mice. We found that chronic administration of uridine to diabetic mice normalized plasma glucose and triglyceride levels and the heart weight/body weight ratio and increased the rate of glucose utilization during the intraperitoneal glucose tolerance test. Analysis of TEM revealed that uridine prevented diabetes-induced ultrastructural abnormalities in mitochondria and sarcomeres in ventricular cardiomyocytes. In diabetic heart tissue, the mRNA level of Ppargc1a decreased and Drp1 and Parkin gene expression increased, suggesting the disturbances of mitochondrial biogenesis, fission, and mitophagy, respectively. Uridine treatment of diabetic mice restored the mRNA level of Ppargc1a and enhanced Pink1 gene expression, which may indicate an increase in the intensity of mitochondrial biogenesis and mitophagy, and as a consequence, mitochondrial turnover. Uridine also reduced oxidative phosphorylation dysfunction and suppressed lipid peroxidation, but it had no significant effect on the impaired calcium retention capacity and potassium transport in the heart mitochondria of diabetic mice. Altogether, these findings suggest that, along with its hypoglycemic effect, uridine has a protective action against diabetes-mediated functional and structural damage to cardiac mitochondria and disruption of mitochondrial quality-control systems in the diabetic heart.

Metabolic reprogramming: A novel therapeutic target in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes mellitus. However, the pathological mechanisms contributing to DKD are multifactorial and poorly understood. Diabetes is characterized by metabolic disorders that can bring about a series of changes in energy metabolism. As the most energy-consuming organs secondary only to the heart, the kidneys must maintain energy homeostasis. Aberrations in energy metabolism can lead to cellular dysfunction or even death. Metabolic reprogramming, a shift from mitochondrial oxidative phosphorylation to glycolysis and its side branches, is thought to play a critical role in the development and progression of DKD. This review focuses on the current knowledge about metabolic reprogramming and the role it plays in DKD development. The underlying etiologies, pathological damages in the involved cells, and potential molecular regulators of metabolic alterations are also discussed. Understanding the role of metabolic reprogramming in DKD may provide novel therapeutic approaches to delay its progression to end-stage renal disease.

Macrophage Polarization Mediated by Mitochondrial Dysfunction Induces Adipose Tissue Inflammation in Obesity

Obesity is one of the prominent global health issues, contributing to the growing prevalence of insulin resistance and type 2 diabetes. Chronic inflammation in adipose tissue is considered as a key risk factor for the development of insulin resistance and type 2 diabetes in obese individuals. Macrophages are the most abundant immune cells in adipose tissue and play an important role in adipose tissue inflammation. Mitochondria are critical for regulating macrophage polarization, differentiation, and survival. Changes to mitochondrial metabolism and physiology induced by extracellular signals may underlie the corresponding state of macrophage activation. Macrophage mitochondrial dysfunction is a key mediator of obesity-induced macrophage inflammatory response and subsequent systemic insulin resistance. Mitochondrial dysfunction drives the activation of the NLRP3 inflammasome, which induces the release of IL-1β. IL-1β leads to decreased insulin sensitivity of insulin target cells via paracrine signaling or infiltration into the systemic circulation. In this review, we discuss the new findings on how obesity induces macrophage mitochondrial dysfunction and how mitochondrial dysfunction induces NLRP3 inflammasome activation. We also summarize therapeutic approaches targeting mitochondria for the treatment of diabetes.

Alisporivir Normalizes Mitochondrial Function of Primary Mouse Lung Endothelial Cells Under Conditions of Hyperglycemia

Effect of alisporivir (a mitochondrial permeability transition pore inhibitor) on the development of mitochondrial dysfunction under hyperglycemic conditions in the primary culture of mouse lung endothelial cells was investigated in this work. We demonstrated that hyperglycemia (30 mM glucose for 24 h) leads to the decrease in viability of the pulmonary endotheliocytes, causes mitochondrial dysfunction manifested by the drop in membrane potential and increase in superoxide anion generation as well as facilitates opening of the mitochondrial permeability transition pore (MPT pore). Incubation of endothelial cells with 5 µM alisporivir under hyperglycemic conditions leads to the increase in cell viability, restoration of the membrane potential level and of the MPT pore opening activity to control values. Hyperglycemia causes increased mitophagy in the lung endothelial cells: we observed increase in the degree of colocalization of mitochondria and lysosomes and upregulation of the Parkin gene expression. Alisporivir restores these parameters back to the levels observed in the control cells. Hyperglycemia results in the increase in the expression of the Drp1 gene in endotheliocytes responsible for synthesis of the protein involved in the process of mitochondria fission. Alisporivir does not significantly alter expression of the genes. The paper discusses mechanisms of the effect of alisporivir on mitochondrial dysfunction in murine pulmonary endotheliocytes under conditions of hyperglycemia.

PTEN-induced kinase 1 deficiency alters albumin permeability and insulin signaling in podocytes

Alterations of insulin signaling in diabetes are associated with podocyte injury, proteinuria, and renal failure. Insulin stimulates glucose transport to cells and regulates other intracellular processes that are linked to cellular bioenergetics, such as autophagy, gluconeogenesis, fatty acid metabolism, and mitochondrial homeostasis. The dysfunction of mitochondrial dynamics, including mitochondrial fusion, fission, and mitophagy, has been observed in high glucose-treated podocytes and renal cells from patients with diabetes. Previous studies showed that prolonged hyperglycemia is associated with the development of insulin resistance in podocytes, and high glucose-treated podocytes exhibit an increase in mitochondrial fission and decrease in markers of mitophagy. In the present study, we found that deficiency of the main mitophagy protein PTEN-induced kinase 1 (PINK1) significantly increased albumin permeability and hampered glucose uptake to podocytes. We suggest that PINK1 inhibition impairs the insulin signaling pathway, in which lower levels of phosphorylated Akt and membrane fractions of the insulin receptor and glucose transporter-4 were observed. Moreover, PINK1-depleted podocytes exhibited lower podocin and nephrin expression, thus identifying a potential mechanism whereby albumin leakage increases under hyperglycemic conditions when mitophagy is inhibited. In conclusion, we found that PINK1 plays an essential role in insulin signaling and the maintenance of proper permeability in podocytes. Therefore, PINK1 may be a potential therapeutic target for the treatment or prevention of diabetic nephropathy.

Podocyte Injury in Diabetic Kidney Disease: A Focus on Mitochondrial Dysfunction

Podocytes are a crucial cellular component in maintaining the glomerular filtration barrier, and their injury is the major determinant in the development of albuminuria and diabetic kidney disease (DKD). Podocytes are rich in mitochondria and heavily dependent on them for energy to maintain normal functions. Emerging evidence suggests that mitochondrial dysfunction is a key driver in the pathogenesis of podocyte injury in DKD. Impairment of mitochondrial function results in an energy crisis, oxidative stress, inflammation, and cell death. In this review, we summarize the recent advances in the molecular mechanisms that cause mitochondrial damage and illustrate the impact of mitochondrial injury on podocytes. The related mitochondrial pathways involved in podocyte injury in DKD include mitochondrial dynamics and mitophagy, mitochondrial biogenesis, mitochondrial oxidative phosphorylation and oxidative stress, and mitochondrial protein quality control. Furthermore, we discuss the role of mitochondria-associated membranes (MAMs) formation, which is intimately linked with mitochondrial function in podocytes. Finally, we examine the experimental evidence exploring the targeting of podocyte mitochondrial function for treating DKD and conclude with a discussion of potential directions for future research in the field of mitochondrial dysfunction in podocytes in DKD.

Emergent players in renovascular disease

Renovascular disease (RVD) remains a common etiology of secondary hypertension. Recent clinical trials revealed unsatisfactory therapeutic outcomes of renal revascularization, leading to extensive investigation to unravel key pathophysiological mechanisms underlying irreversible functional loss and structural damage in the chronically ischemic kidney. Research studies identified complex interactions among various players, including inflammation, fibrosis, mitochondrial injury, cellular senescence, and microvascular remodeling. This interplay resulted in a shift of our understanding of RVD from a mere hemodynamic disorder to a pro-inflammatory and pro-fibrotic pathology strongly influenced by systemic diseases like metabolic syndrome (MetS), hypertension, diabetes mellitus, and hyperlipidemia. Novel diagnostic approaches have been tested for early detection and follow-up of RVD progression, using new imaging techniques and biochemical markers of renal injury and dysfunction. Therapies targeting some of the pathological pathways governing the development of RVD have shown promising results in animal models, and a few have moved from bench to clinical research. This review summarizes evolving understanding in chronic ischemic kidney injury.

Upregulation of TIPE1 in tubular epithelial cell aggravates diabetic nephropathy by disrupting PHB2 mediated mitophagy

Renal tubular epithelial cells (RTECs) are one of the most mitochondria-rich cell types, and are thus vulnerable to mitochondrial dysregulation, which is defined as a pivotal event in tubular damage in diabetic nephropathy (DN). However, the underlying mechanisms remain largely unknown. Here, we investigated the role and mechanisms of tumor necrosis factor alpha-induced protein 8-like 1 (TNFAIP8L1/TIPE1) in high glucose (HG)-induced mitochondrial dysfunction in RTECs and DN progression. TIPE1 expression was predominantly upregulated in RTECs in patients with DN and mice with streptozotocin (STZ)-induced DN. Conditional knockout of Tipe1 in RTECs significantly decreased the urine protein creatinine ratio, renal tubular damage, epithelial-mesenchymal transition, and interstitial fibrosis in STZ-induced mice. RNA sequencing revealed that citrate cycle-related genes were positively enriched in the renal tissues of RTEC-specific Tipe1 knockout mice. Tipe1 deficiency upregulated ATP levels, mitochondrial membrane potential, and respiration rate, but downregulated mitochondrial ROS levels in RTECs. Furthermore, Tipe1 ablation led to enhanced mitophagy in RTECs, indicative of increased LC3II, PINK1, and Parkin expression, but decreased p62 expression in mitochondria. Mechanistically, mass spectrometry screening and co-immunoprecipitation assays revealed the interaction of TIPE1 with prohibitin 2 (PHB2), a crucial mitophagy receptor. Intriguingly, TIPE1 promoted the ubiquitination and proteasomal degradation of PHB2. Subsequently, PHB2 knockdown almost abrogated the improvement of Tipe1 loss on HG-induced tubular cell mitophagy and damage. Thus, TIPE1 disrupts mitochondrial homeostasis in RTECs and promotes tubular damage by destabilizing PHB2 under HG conditions. Hence, TIPE1 may act as a potential therapeutic target to prevent DN progression.

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TIPE1 is highly expressed in RTECs of DN.

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TIPE1 aggravates diabetic renal injury and fibrosis.

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TIPE1 disrupts the mitochondria homeostasis of RTECs by inhibiting mitophagy.

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TIPE1 interacts with and promotes the proteasomal degradation of PHB2.