Mitochondrial dysfunction in diabetic tubulopathy

Combining mitochondrial proteomes and Mendelian randomization to identify novel therapeutic targets for diabetic nephropathy

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. Mitochondrial dysfunction in the kidney caused by diabetes has previously been linked to the pathogenesis of DN. By mass spectrometry, we identified characteristic proteins of DN from the renal mitochondria in mouse model. To identify the core proteins among them, Mendelian randomization (MR) analysis, microarray data validation, and drug-target interaction analysis were employed. MR analysis found that 189 candidate targets had a causal link with DN risk factors (estimated glomerular filtration rate (eGFR), urinary albumin excretion, and serum creatinine). After systematic analysis, we validated that SLC25A16, CTNND1, C2CD2L, ALDH3A2, NEU1, APEH, CORO1A, NUDT19, and NDUFA4L2 are the core proteins with promising druggability in DN. This study suggests the feasibility of using MR analysis for DN drug target screening, and provides potential insights into mitochondrial dysfunction research, which may contribute to further DN pathogenesis exploration.

Integrative analysis of mitochondrial and immune pathways in diabetic kidney disease: identification of AASS and CASP3 as key predictors and therapeutic targets

OBJECTIVES

Diabetic kidney disease (DKD) is driven by mitochondrial dysfunction and immune dysregulation, yet the mechanistic interplay remains poorly defined. This study aimed to identify key molecular networks linking mitochondrial and immune pathways to DKD progression, with a focus on uncovering biomarkers and therapeutic targets.

METHODS

We conducted an integrative analysis of human DKD cohorts (GSE30122, GSE96804) using weighted gene co-expression network analysis (WGCNA) to identify gene modules enriched for immune response genes and mitochondrial pathways (from MitoCarta3.0). Machine learning algorithms were employed to prioritize key biomarkers for further investigation. Experimental validation was performed using a DKD rat model.

RESULTS

WGCNA revealed significant gene modules associated with immune responses and mitochondrial functions. Machine learning analysis highlighted two central biomarkers: aminoadipate-semialdehyde synthase (AASS) and caspase-3 (CASP3). In the DKD rat model, elevated levels of AASS and CASP3 were found to correlate with increased oxidative stress. Mechanistically, AASS was shown to drive mitochondrial damage via lysine metabolism, while CASP3 amplified inflammatory apoptosis pathways.

CONCLUSIONS

Our findings establish AASS and CASP3 as dual biomarkers and therapeutic targets, bridging mitochondrial-immune crosstalk to DKD pathogenesis. This multi-omics framework provides actionable insights for targeting kidney damage in diabetes.

PINK1 affects mitochondrial oxidative phosphorylation by regulating MFN2 to alleviate diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is widely recognized as a prevalent and major microvascular complication of diabetes mellitus. Mitofusin 2 (MFN2) has been closely linked to the development of diabetes mellitus, yet its precise role in the pathogenesis of DKD remains uncertain. The objective of our current research was to explore the role of MFN2 in the advanced DKD and its underlying molecular pathway. This research was to examine the involvement and molecular pathways of MFN2 in the advancement of DKD.

METHODS

In this study, MFN2 was manipulated in high glucose (HG)-treated HK2 cells to investigate its impact on cell proliferation, apoptosis, and mitochondrial oxidative phosphorylation. Models of MFN2 overexpression or silencing were established in db/db mice as a diabetes model. The alterations in kidney morphology, renal fibrosis severity, macrophage polarization, and related inflammatory factors (tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6], and interleukin-1β [IL-1β]) were evaluated. Furthermore, HK2 cells were co-cultivated with M1-type macrophages to examine the impact of MFN2 expression on macrophage polarization. Subsequently, we delved deeper into the upstream mechanisms utilizing the STRING database.

RESULTS

Our study identified that MFN2 expression was downregulated in HG-treated HK-2 cells. The overexpression of MFN2 resulted in increased HK2 cell proliferation, improved degree of oxidative phosphorylation, and reduced apoptosis. In db/db mice, MFN2 overexpression exerted a protective effect on DKD-induced nephropathy and fibrosis. Notably, MFN2 overexpression influenced macrophage polarization and modulated expression of related inflammatory factors by promoting mitochondrial oxidative phosphorylation. Additionally, STRING database prediction revealed that PTEN-induced kinase 1 (PINK1) regulated MFN2 expression, which was consistent with MFN2 changes in DKD, and this regulation was associated with DKD progression.

CONCLUSION

The role of MFN2 in maintaining mitochondrial function in DKD may be regulated by PINK1 and provides a new potential therapeutic target for DKD.

Angiotensin-Converting Enzyme-Dependent Intrarenal Angiotensin II Contributes to CTP: Phosphoethanolamine Cytidylyltransferase Downregulation, Mitochondrial Membranous Disruption, and Reactive Oxygen Species Overgeneration in Diabetic Tubulopathy

Aims: The limited therapeutic options for diabetic tubulopathy (DT) in early diabetic kidney disease (DKD) reflect the difficulty of targeting renal tubular compartment. While renin-angiotensin-aldosterone system (RAS) inhibitors are commonly utilized in the management of DKD, how intrarenal RAS contributes to diabetic tubular injury is not fully understood. Mitochondrial disruption and reactive oxygen species (ROS) overgeneration have been involved in diabetic tubular injury. Herein, we aim to test the hypothesis that angiotensin-converting enzyme (ACE)-dependent intrarenal angiotensin II (AngII) disrupts tubular mitochondrial membranous homeostasis and causes excessive ROS generation in DT. Results: Mice suffered from renal tubular mitochondrial disruption and ROS overgeneration following high-fat diet/streptozocin-type 2 diabetic induction. Intrarenal AngII generation is ACE-dependent in DT. Local AngII accumulation in renal tissues was achieved by intrarenal artery injection. ACE-dependent intrarenal AngII-treated mice exhibit markedly elevated levels of makers of tubular injury. CTP: Phosphoethanolamine cytidylyltransferase (PCYT2), the primary regulatory enzyme for the biosynthesis of phosphatidylethanolamine, was enriched in renal tubules according to single-cell RNA sequencing. ACE-dependent intrarenal AngII-induced tubular membranous disruption, ROS overgeneration, and PCYT2 downregulation. The diabetic ambiance deteriorated the detrimental effect of ACE-dependent intrarenal AngII on renal tubules. Captopril, the ACE inhibitor (ACEI), showed efficiency in partially ameliorating ACE-dependent intrarenal AngII-induced tubular deterioration pre- and post-diabetic induction. Innovation and Conclusion: This study uncovers a critical role of ACE-dependent intrarenal AngII in mitochondrial membranous disruption, ROS overgeneration, and PCYT2 deficiency in diabetic renal tubules, providing novel insight into DT pathogenesis and ACEI-combined therapeutic targets. Antioxid. Redox Signal. 42, 767-786.

An update on renal tubular injury as related to glycolipid metabolism in diabetic kidney disease

Diabetic kidney disease (DKD) is a severe microvascular complication of diabetes, which can result in end-stage renal disease (ESRD). As the main site of renal reabsorption and its exposed environment, renal tubules can be damaged by various factors. Recent studies have shown that renal tubular epithelial cells (RTECs) injury plays an important role in the occurrence and progression of DKD. The glycolipid metabolism disorders are a vital factor contributing to RTECs injury, which in turn affects the progression of DKD. Abnormal glucose and lipid metabolism can cause oxidative stress, mitochondrial damage, cell apoptosis and lipid accumulation, which can cause RTECs injury. Therefore, this review describes the main pathological mechanism of the injury caused by glycolipid metabolism and the corresponding therapeutic drugs in the clinical treatment of DKD.

Research progress of effective components of traditional Chinese medicine in intervening apoptosis of renal tubular epithelial cells in diabetic kidney disease

ETHNOPHARMACOLOGICAL RELEVANCE

Apoptosis of renal tubular epithelial cells (RTECs) is a critical pathological feature of diabetic kidney disease (DKD), a primary contributor to end-stage renal disease (ESRD). Traditional Chinese medicine (TCM) has shown potential in modulating RTECs apoptosis and alleviating DKD progression, making it a promising area for further investigation.

AIM OF THE STUDY

This study aims to summarize the apoptotic pathways implicated in DKD, analyze existing research on the effects of TCM monomers and compounds on RTECs apoptosis, and elucidate the molecular mechanisms underlying these effects. Additionally, this study emphasizes the significant role of TCM in mitigating DKD progression.

MATERIALS AND METHODS

Relevant literature was systematically retrieved from ancient Chinese medicine texts and modern scientific databases, including CNKI, Web of Science, and PubMed, using keywords such as "Traditional Chinese Medicine", "Diabetic Kidney Disease", "Diabetic Nephropathy", "Renal Tubular Epithelial Cells", and "Apoptosis". The collected information was synthesized and analyzed.

RESULTS

This review systematically analyzed 187 relevant studies, focusing on the mechanisms and clinical applications of 16 TCM monomers and 20 TCM compounds in DKD treatment. Key bioactive compounds, such as berberine, astragaloside IV, and tanshinone IIA, have demonstrated renoprotective effects by mitigating oxidative stress and inflammation, as well as regulating critical signaling pathways, including PI3K/Akt, NF-κB, and TGF-β/Smad, to suppress RTECs apoptosis and decelerate DKD progression. Additionally, several TCM compounds have shown significant efficacy in clinical studies, reducing proteinuria and enhancing renal function, thereby reinforcing the therapeutic potential of TCM in DKD management.

CONCLUSIONS

RTECs apoptosis is a critical pathological feature of DKD. TCM exhibits significant therapeutic potential by intervening in this process through multiple pathways. This study highlights the ability of TCM to exert anti-apoptotic and renoprotective effects by modulating oxidative stress, inflammatory responses, and multiple cellular signaling pathways. The multi-component and multi-target characteristics of TCM offer a promising avenue for the development of novel therapeutic strategies. However, further rigorous research and high-quality clinical trials are required to validate its efficacy and elucidate its mechanisms of action.

Tangshenning formula alleviates tubular injury in diabetic kidney disease via the Sestrin2/AMPK/PGC-1α axis: Restoration of mitochondrial function and inhibition of ferroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Tangshenning (TSN) is a traditional Chinese medicinal formula developed on principles of kidney tonification and collateral unblocking. TSN, formulated from Astragalus mongholicus Bunge, Rheum palmatum L., Ligusticum chuanxiong Hort., and Rosa laevigata Michx., has demonstrated significant clinical efficacy in the treatment of diabetic kidney disease (DKD). Our previous studies have suggested that TSN mitigates tubular injury in DKD by inhibiting ferroptosis, however, the precise molecular targets and mechanistic pathways underlying these effects remain to be fully elucidated.

AIM OF THE STUDY

We investigated whether the Sestrin2/AMPK/PGC-1α axis serves as a key pathway mediating TSN's protective effects against tubular injury in DKD.

METHODS

In vivo, a spontaneous DKD mouse model was developed using KK-Ay mice. In vitro, human tubular epithelial cells (TECs) were used to establish high glucose and ferroptosis models, as well as a Sestrin2 knockdown model for further analysis. Molecular docking was utilized to examine the binding interactions between TSN's key active components and Sestrin2. Colocalization of Sestrin2 and GPX4 was assessed using dual fluorescence staining. Protein expression levels related to the Sestrin2/AMPK/PGC-1α pathway, ferroptosis markers (SLC7A11 and GPX4), and the tubular injury marker KIM-1 were quantified via Western blot analysis. In vivo, DHE staining, TUNEL staining, and ferrous ion content measurement were performed to evaluate ferroptosis levels in renal tissue. In vitro, the BODIPY 581/591 C11 probe and ferrous ion assay were used to assess ferroptosis levels in TECs. MitoSOX staining, JC-1 assay, and ATP level measurements were conducted to evaluate mitochondrial function in TECs.

RESULTS

In vivo, our results demonstrated that TSN improved renal function, alleviated tubular injury, and reduced pathological damage in DKD mice. Furthermore, TSN upregulated the protein expression of the Sestrin2/AMPK/PGC-1α axis and decreased ferroptosis-related markers in the DKD mouse model. Similarly, in vitro, TSN enhanced the expression of the Sestrin2/AMPK/PGC-1α pathway, restored mitochondrial function, and inhibited ferroptosis in TECs under high glucose and ferroptosis-inducing conditions. Additionally, downregulation of Sestrin2 impaired the therapeutic effects of TSN.

CONCLUSION

TSN alleviates tubular injury in DKD by activating the Sestrin2/AMPK/PGC-1α pathway, restoring mitochondrial function, and inhibiting ferroptosis in TECs.

Loureirin B analogs mitigate oxidative stress and confer renal protection

Diabetic kidney disease (DKD) is a microvascular complication of diabetes with high morbidity and mortality, necessitating effective treatment. In this study, the Loureirin B analogue (LB-A) was utilized to treat DKD in mice. The results demonstrated that LB-A effectively prevent the progression of DKD in mice, significantly lowering fasting blood glucose levels and reducing proteinuria levels. Additionally, there was a significant decrease in oxidase content in the kidneys of mice, accompanied by an increase in antioxidant oxidase content, resulting in a decrease in ROS levels, mitigating oxidative stress state through modulation of Cxcl1. Cell experiments further confirmed that reducing Cxcl1/Cxcr2 axis activation prevented the onset of DKD induced by high glucose exposure and affected the therapeutic effect of LB-A as well. These findings provide evidences to support that LB-A may mitigate oxidative stress by modulating the Cxcl1 signaling pathway, thereby contributing to renal protection in the context of DKD treatment.

Control of Mitochondrial Quality: A Promising Target for Diabetic Kidney Disease Treatment

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD), affecting over 40% of patients with diabetes. DKD progression involves fibrosis and damage to glomerular and tubulointerstitial regions, with mitochondrial dysfunction playing a critical role. Impaired mitochondria lead to reduced adenosine triphosphate (ATP) production, damaged mitochondria accumulation, and increased reactive oxygen species (ROS), contributing to renal deterioration. Maintaining mitochondrial quality control (MQC) is essential for preventing cell death, tissue injury, and kidney failure. Recent clinical trials show that enhancing MQC can alleviate DKD. However, current treatments cannot halt kidney function decline, underscoring the need for new therapeutic strategies. Mitochondrial-targeted drugs show potential; however, challenges remain because of adverse effects and unclear mechanisms. Future research should aim to comprehensively explore therapeutic potential of MQC in DKD. This review highlights the significance of MQC in DKD treatment, emphasizing the need to maintain mitochondrial quality for developing new therapies.

ERK1/2 gene expression and hypomethylation of Alu and LINE1 elements in patients with type 2 diabetes with and without cataract: Impact of hyperglycemia-induced oxidative stress

AIMS

This study aimed to delineate the effect of hyperglycemia on the Alu/LINE-1 hypomethylation and in ERK1/2 genes expression in type 2 diabetes with and without cataract.

METHODS

This study included 58 diabetic patients without cataracts, 50 diabetic patients with cataracts, and 36 healthy controls. After DNA extraction and bisulfite treatment, LINE-1 and Alu methylation levels were assessed using Real-time MSP. ERK1/2 gene expression was analyzed through real-time PCR. Total antioxidant capacity (TAC), and fasting plasma glucose (FPG) were measured using colorimetric methods. Statistical analysis was performed with SPSS23, setting the significance level at P < 0.05.

RESULTS

The TAC levels were significantly lower for cataract and diabetic groups than controls (259.31 ± 122.99, 312.43 ± 145.46, 372.58 ± 132.95 nanomole of Trolox equivalent) with a significant correlation between FPG and TAC levels in both the cataract and diabetic groups (P < 0.05). Alu and LINE-1 sequences were found to be statistically hypomethylated in diabetic and cataract patients compared to controls. In these groups, TAC levels were directly correlated with Alu methylation (P < 0.05) but not LINE-1. ERK1/2 gene expression was significantly higher in diabetic and cataract patients, showing increases of 2.41-fold and 1.43-fold for ERK1, and 1.27-fold and 1.5 for ERK2, respectively. ERK1 expression correlated significantly with FPG levels. A reverse correlation was observed between TAC levels and ERK1/2 expression.

CONCLUSIONS

Our findings indicate that hyperglycemia-induced oxidative stress may alter ERK1/2 gene expression patterns and induce aberrant hypomethylation in Alu and LINE-1 sequences. These aberrant changes may play a contributing role in diabetic complications such as cataracts.

A comprehensive bioinformatics analysis identifies mitophagy biomarkers and potential Molecular mechanisms in hypertensive nephropathy

Mitophagy, the selective removal of damaged mitochondria, plays a critical role in kidney diseases, but its involvement in hypertensive nephropathy (HTN) is not well understood. To address this gap, we investigated mitophagy-related genes in HTN, identifying potential biomarkers for diagnosis and treatment. Transcriptome datasets from the Gene Expression Omnibus database were analyzed, resulting in the identification of seven mitophagy related differentially expressed genes (MR-DEGs), namely PINK1, ULK1, SQSTM1, ATG5, ATG12, MFN2, and UBA52. Further, we explored the correlation between MR-DEGs, immune cells, and inflammatory factors. The identified genes demonstrated a strong correlation with Mast cells, T-cells, TGFβ3, IL13, and CSF3. Machine learning techniques were employed to screen important genes, construct diagnostic models, and evaluate their accuracy. Consensus clustering divided the HTN patients into two mitophagy subgroups, with Subgroup 2 showing higher levels of immune cell infiltration and inflammatory factors. The functions of their proteins primarily involve complement, coagulation, lipids, and vascular smooth muscle contraction. Single-cell RNA sequencing revealed that mitophagy was most significant in proximal tubule cells (PTC) in HTN patients. Pseudotime analysis of PTC confirmed the expression changes observed in the transcriptome. Intercellular communication analysis suggested that mitophagy might regulate PTC's participation in intercellular crosstalk. Notably, specific transcription factors such as HNF4A, PPARA, and STAT3 showed strong correlations with mitophagy-related genes in PTC, indicating their potential role in modulating PTC function and influencing the onset and progression of HTN. This study offers a comprehensive analysis of mitophagy in HTN, enhancing our understanding of the pathogenesis, diagnosis, and treatment of HTN.

Label-free whole-kidney metabolic optical imaging using in vivo insulated cryofixation and cryo-micro-optical sectioning tomography

Cryo-imaging has the potential to obtain and visualize the metabolic state of the whole kidney without labeling. However, uneven fixation of metabolic information and incomplete organ morphology in three dimensions limit cryo-imaging application. Here, a pipeline of in vivo insulated cryofixation combined with cryo-micro optical sectioning tomography (cryo-MOST) was established to achieve uniform and complete cryofixation and three-dimensional visualization of renal metabolic mapping at a micron-scale resolution. By this pipeline, we discovered an increased renal redox ratio of db/db mice with type 2 diabetes, indicating the presence of metabolic disorders. The results demonstrate that our convenient optical imaging tool provides a micro-resolution, quantitative assessment of the metabolic state of the whole kidney and potentially extends to other organs.

Modulating HIF-1α/HIF-2α homeostasis with Shen-Qi-Huo-Xue formula alleviates tubular ferroptosis and epithelial-mesenchymal transition in diabetic kidney disease

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic kidney disease (DKD) is one of the main types of chronic kidney disease, which seriously affects the quality of life of patients. Shen-Qi-Huo-Xue formula (SQHXF), based on the Shen-Qi-Di-Huang decoction, is a traditional Chinese medicine formula for DKD. This study explored the mechanism of action of SQHXF on DKD through analysis of drug components, in vivo and in vitro experiments.

AIM OF THE STUDY

To elucidate the regulatory mechanisms of HIF-1α/HIF-2α homeostasis on ferroptosis and epithelial-mesenchymal transition (EMT) in renal tubular epithelial cells and the mechanism of action of SQHXF against DKD.

METHODS

The components of SQHXF were analyzed using UPLC-Q Exactive HF/MS. The effects of SQHXF on renal function, urinary proteins, glucose-lipid metabolism, hepatic function, renal tissue hypoxia, ferroptosis and EMT were analyzed following gavage of DKD model mice with different SQHXF doses. The effects of changes in HIF-1α and HIF-2α expression on ferroptosis and EMT, as well as the modulatory effects of SQHXF-containing serum, were assessed in vitro. The potential feedback mechanism of HIFs/ferroptosis/EMT was elucidated using HIF-1α knockdown and a ferroptosis inhibitor.

RESULTS

One-hundred and fifty compounds in SQHXF were tested for bloodstream entry. In vivo study showed that SQHXF was able to reduce creatinine, uric acid, fasting plasma glucose, 24-h urinary protein, low-density lipoprotein cholesterol, and aspartate aminotransferase levels, up-regulate HIF-1α, down-regulate HIF-2α, reduce ferroptosis, and alleviate renal fibrosis and EMT in tubular epithelial cells. HIF-1α/HIF-2α imbalance promoted ferroptosis and EMT in HK-2 cells, which was attenuated by SQHXF-containing serum. HIF-1α knockdown decreased HIF-2α expression and reduced ferroptosis and EMT. Inhibition of ferroptosis reduced EMT but failed to regulate HIF-1α and HIF-2α.

CONCLUSIONS

SQHXF alleviated ferroptosis and EMT, improved liver and kidney function, reduced proteinuria, and alleviated renal lesions by maintaining equilibrium between HIF-1α and HIF-2α.

Mitochondria-dependent apoptosis was involved in the alleviation of Jujuboside A on diabetic kidney disease-associated renal tubular injury via YY1/PGC-1α signaling

BACKGROUND

Renal tubular injury was a significant pathological change of diabetic kidney disease (DKD), and the amelioration of renal tubular injury through mitochondrial function was an important treatment strategy of DKD. Our previous study had revealed that Jujuboside A (Ju A), the main active substance isolated from Semen Ziziphi Spinosae (SZS), could restore renal function of diabetic mice. However, its protective mechanism against DKD remains unclear.

PURPOSE

To investigate the effects and the mechanism of Ju A against DKD-associated renal tubular injury.

STUDY DESIGN AND METHODS

The anti-apoptotic effect of Ju A and its protection effect on mitochondria dysfunction of renal tubular epithelial cells (RTECs) were examined in high glucose (HG)-cultured HK-2 cells, and in db/db mice. Subsequently, Network Pharmacology analysis, molecular docking, luciferase assay, chromatin immunoprecipitation (ChIP), Yin Yang 1 (YY1) overexpression lentiviral vector and peroxisome proliferator-activated receptor-γ coactlvator-1α (PGC-1α) specific agonist ZLN005 were all used to identify the protective mechanism of Ju A towards DKD-associated mitochondrial dysfunction of RTECs.

RESULTS

Ju A inhibited RTECs apoptosis and ameliorated mitochondria dysfunction of RTECs of diabetic mice, and HG-cultured HK-2 cells. YY1 was the potential target of Ju A against DKD-related mitochondrial dysfunction, and the down-regulation of YY1 induced by Ju A increased PGC-1α promoter activity, leading to the restored mitochondrial function of HG-treated HK-2 cells. Renal tubule specific overexpression of YY1 intercepted the renal protective effect of Ju A on diabetic mice via blocking PGC-1α-mediated restoration of mitochondrial function of RTECs. The in-depth mechanism research revealed that the protective effect of Ju A towards DKD-associated renal tubular injury was linked to the restored mitochondrial function through YY1/PGC-1α signaling, resulting in the inhibited apoptosis of RTECs in diabetic condition via inactivating CytC-mediated Caspase9/Caspase3 signaling.

CONCLUSION

Ju A through the inhibition of mitochondria-dependent apoptosis alleviated DKD-associated renal tubular injury via YY1/PGC-1α signaling.

p21-Activated Kinase 4 and Ischemic Acute Kidney Injury in Mice and Humans

Background

AKI after ischemia-reperfusion remains a substantial perioperative challenge lacking effective treatment. p21-activated kinase 4 (PAK4), a downstream effector of Rho GTPase, has been explored in hepatic ischemia-reperfusion injury, but its role in renal ischemia-reperfusion is unknown.

Methods

Wild-type and proximal tubule–specific Pak4 knockout mice underwent 25 minutes of ischemia followed by 24 hours of reperfusion injury. Primary tubular cells and human kidney-2 cells were exposed to hypoxia-reoxygenation injury to investigate the in vitro effect of PAK4. Selective degradation of PAK4 was employed using proteolysis-targeting chimera (PROTAC) to ameliorate AKI.

Results

Post–ischemia-reperfusion, the expression of PAK4 was upregulated through hypoxia-inducible factor 1 α in mouse kidneys. Deletion of PAK4 in proximal tubule cells, but not in myeloid cells, significantly mitigated ischemia-reperfusion–induced AKI, as evidenced by decreased levels of BUN, creatinine, tubular necrosis, apoptosis, macrophage infiltration, and lipid accumulation compared with control mice. Further investigation revealed that PAK4 phosphorylated GSH peroxidase 3 (GPx3) at T47, leading to its proteasomal degradation. In addition, pretreatment of mice with the PAK4 PROTAC preserved GPx3 and enhanced fatty acid β-oxidation, thereby protecting against AKI. In kidney tissues from people with a kidney transplant, elevated levels of PAK4 protein and phosphorylation of GPx3 at T47 were observed.

Conclusions

Renal tubular PAK4 contributes to tissue damage during ischemia-reperfusion injury, whereas PAK4 PROTAC mitigates ischemia-reperfusion injury by reducing oxidative stress and promoting fatty acid β-oxidation.

MTDH inhibits CrAT to promote mitochondrial damage in palmitic acid-induced renal tubular cells

PURPOSE

Mitochondrial dysfunction leading to impaired energy metabolism has been recognized as a pivotal factor contributing to renal tubular epithelial cells (RTECs) damage in the context of dyslipidemia conditions in diabetic kidney disease (DKD). The primary objective of this study is to elucidate the role and underlying mechanism of the proto-oncogene Metadherin (MTDH) in mediating mitochondrial damage within this specific pathological context in vitro.

METHODS

The expression of MTDH in RTECs was modulated by transfecting small interfering RNA and plasmid, while palmitic acid (PA) was employed to simulate diabetic lipid metabolism disorder. Mitochondrial damage was evaluated by examining various parameters including mitochondrial morphology, membrane potential, reactive oxygen species (ROS) production, adenosine triphosphate (ATP) production, as well as morphological and structural alterations. Additionally, Carnitine acetyltransferase (CrAT) expression was assessed using Western blotting and quantitative real-time polymerase chain reaction, and CrAT activity was quantified.

RESULT

MTDH expression was upregulated in PA-induced RTECs, while CrAT expression and activity were inhibited. Downregulation of MTDH mitigated PA-induced mitochondrial damage, as demonstrated by the preservation of mitochondrial membrane potential, reduction in mitochondrial ROS production, prevention of ATP depletion, and maintenance of mitochondrial structure. This was accompanied by an upregulation in CrAT expression and activity. Conversely, overexpression of MTDH exacerbated mitochondrial dysfunction by impairing membrane potential, augmenting mitochondrial ROS production, inhibiting ATP synthesis, and suppressing CrAT expression and activity.

CONCLUSION

In the context of dyslipidemia conditions, MTDH is upregulated and suppresses the expression and activity of CrAT in RTECs, thereby inducing mitochondrial dysfunction and perturbing energy metabolism. These alterations exacerbate the injury to RTECs, consequently promoting the progression of DKD.

The role and mechanism of m6A methylation in diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus, characterized by progressive deterioration of renal structure and function, which may eventually lead to end-stage kidney disease (ESKD). The N6-methyladenosine (m6A) methylation, an important modality of RNA modification, involves three classes of key regulators, writers (e.g., METTL3), erasers (e.g., FTO, ALKBH5) and readers (e.g., YTHDF2), which play important roles in DN. Writers are responsible for introducing m6A modifications on RNAs, erasers remove m6A modifications and readers recognize and bind m6A-modified RNAs to regulate RNAs functions, such as mRNA stability, translation and localization. In DN, abnormal m6A modification may promote kidney injury and proteinuria by regulating key pathways involved in multiple processes, including lipid metabolism and inflammatory response, in kidney cells such as podocytes. Therefore, an in-depth study of the role and mechanism of m6A methylation that are regulated by "writers", "erasers" and "readers" in DN is expected to provide new targets and strategies for the prevention and treatment of DN.

Mitochondrial Dysfunction in Diabetes: Shedding Light on a Widespread Oversight

Diabetes mellitus represents a complicated metabolic condition marked by ongoing hyperglycemia arising from impaired insulin secretion, inadequate insulin action, or a combination of both. Mitochondrial dysfunction has emerged as a significant contributor to the aetiology of diabetes, affecting various metabolic processes critical for glucose homeostasis. This review aims to elucidate the complex link between mitochondrial dysfunction and diabetes, covering the spectrum of diabetes types, the role of mitochondria in insulin resistance, highlighting pathophysiological mechanisms, mitochondrial DNA damage, and altered mitochondrial biogenesis and dynamics. Additionally, it discusses the clinical implications and complications of mitochondrial dysfunction in diabetes and its complications, diagnostic approaches for assessing mitochondrial function in diabetics, therapeutic strategies, future directions, and research opportunities.

New insights in the treatment of DKD: recent advances and future prospects

Diabetic kidney disease (DKD) represents the predominant and severe microvascular complication associated with diabetes, frequently culminating in End-Stage Kidney Disease (ESKD). The escalating prevalence of diabetes has correspondingly led to a rise in DKD incidence, imposing significant challenges on both individuals and society. The etiology of DKD is multifaceted and remains devoid of definitive therapeutic interventions. This article examines the pharmacological actions and mechanisms of different drugs used for the prevention and treatment of DKD that are currently in clinical use or undergoing development. The goal is to offer insights for early intervention based on therapeutic combinations to potentially slow kidney disease progression.

Single-cell atlas reveals multi-faced responses of losartan on tubular mitochondria in diabetic kidney disease

BACKGROUND AND OBJECTIVE

Mitochondria are crucial to the function of renal tubular cells, and their dynamic perturbation in many aspects is an important mechanism of diabetic kidney disease (DKD). Single-nucleus RNA sequencing (snRNA-seq) technology is a high-throughput sequencing analysis technique for RNA at the level of a single cell nucleus. Here, our DKD mouse kidney single-cell RNA sequencing conveys a more comprehensive mitochondrial profile, which helps us further understand the therapeutic response of this unique organelle family to drugs.

METHODS

After high fat diet (HFD), mice were intraperitoneally injected with streptozotocin (STZ) to induce DKD, and then divided into three subsets: CON (healthy) subset, DKD (vehicle) subset, and LST (losartan; 25 mg/kg/day) subset. Divide HK-2 cell into LG (low glucose; 5 mM) and HG (high glucose; 30 mM) and HG + LST (losartan; 1 µ M) subsets. snRNA-seq was performed on the renal tissues of LST and DKD subset mice. To reveal the effects of losartan on gene function and pathway changes in renal tubular mitochondria, Gene Ontology (GO) enrichment analysis and GSEA/GSVA scoring were performed to analyze the specific response of proximal tubular (PT) cell mitochondria to losartan treatment, including key events in mitochondrial homeostasis such as mitochondrial morphology, dynamics, mitophagy, autophagic flux, mitochondrial respiratory chain, apoptosis, and ROS generation. Preliminary validation through in vitro and in vivo experiments, including observation of changes in mitochondrial morphology and dynamics using probes such as Mitotracker Red, and evaluation of the effect of losartan on key events of mitochondrial homeostasis perturbation using electron microscopy, laser confocal microscopy, immunofluorescence, and Western blotting. Detection of autophagic flux in cells by transfecting Ad-mCherry-GFP-LC3B dual fluorescence labeled adenovirus. Various fluorescent probes and energy detector are used to detect mitochondrial apoptosis, ROS, and respiration of mitochondrion.

RESULTS

Through the single-cell atlas of DKD mouse kidneys, it was found that losartan treatment significantly increased the percentage of PT cells. Gene Ontology (GO) enrichment analysis of differentially expressed genes showed enrichment of autophagy of mitochondrion pathway. Further GSEA analysis and GSVA scoring revealed that mitophagy and other key mitochondrial perturbation events, such as ROS production, apoptosis, membrane potential, adenosine triphosphate (ATP) synthesis, and mitochondrial dynamics, were involved in the protective mechanism of losartan on PT cells, thereby improving mitochondrial homeostasis. Consistent results were also obtained in mice and cellular experiments. In addition, we highlighted a specific renal tubular subpopulation with mitophagy phenotype found in single-cell data, and preliminarily validated it with co-localization and increased expression of Pink1 and Gclc in kidney specimens of DKD patients treated with losartan.

CONCLUSIONS

Our research suggests that scRNA-seq can reflect the multifaceted mitochondrial landscape of DKD renal tubular cells after drug treatment, and these findings may provide new targets for DKD therapy at the organelle level.

Curcumin nanocrystals ameliorate ferroptosis of diabetic nephropathy through glutathione peroxidase 4

Objective

The aim of this study was to investigate the effect of curcumin nanocrystals (Cur-NCs) on ferroptosis in high-glucose (HG)-induced HK-2 cells and streptozotocin (STZ)-induced diabetic nephropathy model (DN) rats. The purpose is to determine whether Cur NCs can become a promising treatment option for diabetes nephropathy by reducing ferroptosis.

Methods

Cur-NCs were prepared using microfluidic technology and studied using dynamic light scattering and transmission electron microscopy. HK-2 cells were treated with 30 mM HG to create a renal tubule damage cell model. Then, cell viability was evaluated in HK-2 cells treated with varying concentrations of Cur-NCs (0.23, 0.47, 0.94, 1.87, 3.75, 7.5, 15, and 30 μg/mL) using Cell Counting Kit-8 (CCK-8). Furthermore, in vivo experiments were carried out to investigate the roles of Cur-NCs in STZ-induced DN rats.

Results

The results showed that HG treatment greatly enhanced the levels of LDH, MDA, Iron, lipid ROS, apoptosis, NCOA4, TFR-1, while decreasing the expression of GSH, GPX4, SLC7A11, and FTH-1. These effects induced by HG could be attenuated by Cur-NCs. Cur-NCs also reduced the HG-induced decrease in cell viability, as well as the increase in lipid ROS and cell apoptosis, however erastin could inhibit their effects. Furthermore, the in vivo results showed that Cur-NCs reduced ferroptosis and inhibited renal damage in DN rats.

Conclusion

This study demonstrates that Cur-NCs can significantly attenuate ferroptosis in a STZ-induced renal damage model by recovering GPX4, implying that Cur-NCs may be a promising therapy option for DN.

Identification of mitochondria-related genes as diagnostic biomarkers for diabetic nephropathy and their correlation with immune infiltration: New insights from bioinformatics analysis

BACKGROUND

Diabetic nephropathy (DN) is a common and severe microvascular complication of diabetes. Mitochondrial dysfunction and immune inflammation are important factors in the pathogenesis of DN. However, the specific mechanisms and their intricate interactions in DN remain unclear. Besides, there are no effective specific predictive or diagnostic biomarkers for DN so far. Therefore, this study aims to elucidate the role of mitochondrial-related genes and their possibility as predictive or diagnostic biomarkers, as well as their crosstalk with immune infiltration in the progression of DN.

METHODS

Based on the GEO database and limma R package, the differentially expressed genes (DEGs) of DN were identified. Mitochondrial-related DEGs (MitoDEGs) were then obtained by intersecting these DEGs with mitochondria-related genes from the MitoCarta 3.0 database. Subsequently, the candidate hub genes were further screened by gene co-expression network analysis (WGCNA), and verified mRNA levels of these genes by real-time quantitative PCR (qRT-PCR) in high-glucose-treated human proximal tubular (HK-2) cells. The verified hub genes were utilized to construct a combined diagnostic model for DN, with its diagnostic efficacy assessed across the GSE30122 and GSE96804 datasets. Additionally, the immune infiltration pattern in DN was assessed with the CIBERSORT algorithm, and the Nephroseq v5 database was used to analyze the correlation between hub genes and clinical features of DN.

RESULTS

Seven mitochondria-related candidate hub genes were screened from 56 MitoDEGs. Subsequently, the expression levels of six of them, namely EFHD1, CASP3, AASS, MPC1, NT5DC2, and BCL2A1, exhibited significant inter-group differences in the HK-2 cell model. The diagnostic model based on the six genes demonstrated good diagnostic efficacy in both training and validation sets. Furthermore, correlation analysis indicated that EFHD1 and AASS, downregulated in DN, are positively correlated with eGFR and negatively with serum creatinine. Conversely, CASP3, NT5DC2, and BCL2A1, upregulated in DN, show opposite correlations. In addition, spearman analysis revealed that the six hub genes were significantly associated with the infiltration of immune cells, including M1 and M2 macrophages, mast cells, resting NK cells, gamma delta T cells, and follicular helper T cells.

CONCLUSION

This study elucidated the characteristics of mitochondria-related genes and their correlation with immune cell infiltration in DN, providing new insights for exploring the pathogenesis of DN and facilitating the identification of new potential biomarkers and therapeutic targets.

Protective effect of mesenchymal stromal cells in diabetic nephropathy: the In vitro and In vivo role of the M-Sec-tunneling nanotubes

Mitochondrial dysfunction plays an important role in the development of podocyte injury in diabetic nephropathy (DN). Tunnelling nanotubes (TNTs) are long channels that connect cells and allow organelle exchange. Mesenchymal stromal cells (MSCs) can transfer mitochondria to other cells through the M-Sec-TNTs system. However, it remains unexplored whether MSCs can form heterotypic TNTs with podocytes, thereby enabling the replacement of diabetes-damaged mitochondria. In this study, we analysed TNT formation, mitochondrial transfer, and markers of cell injury in podocytes that were pre-exposed to diabetes-related insults and then co-cultured with diabetic or non-diabetic MSCs. Furthermore, to assess the in vivo relevance, we treated DN mice with exogenous MSCs, either expressing or lacking M-Sec, carrying fluorescent-tagged mitochondria. MSCs formed heterotypic TNTs with podocytes, allowing mitochondrial transfer, via a M-Sec-dependent mechanism. This ameliorated mitochondrial function, nephrin expression, and reduced apoptosis in recipient podocytes. However, MSCs isolated from diabetic mice failed to confer cytoprotection due to Miro-1 down-regulation. In experimental DN, treatment with exogenous MSCs significantly improved DN, but no benefit was observed in mice treated with MSCs lacking M-Sec. Mitochondrial transfer from exogenous MSCs to podocytes occurred in vivo in a M-Sec-dependent manner. These findings demonstrate that the M-Sec-TNT-mediated transfer of mitochondria from healthy MSCs to diabetes-injured podocytes can ameliorate podocyte damage. Moreover, M-Sec expression in exogenous MSCs is essential for providing renoprotection in vivo in experimental DN.

4-Octyl itaconate attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis

Objectives: The aim of this study was to investigate the mechanism of itaconate's potential effect in diabetic kidney disease.

Methods: Renal immune responsive gene 1 (IRG1) levels were measured in db/db mice and streptozotocin (STZ) + high-fat diet (HFD)-induced diabetic mice. Irg1 knockout mice were generated. db/db mice were treated with 4-octyl itaconate (4-OI, 50 mg/kg), a derivative of itaconate, for 4 weeks. Renal function and morphological changes were investigated. Ultrastructural alterations were determined by transmission electron microscopy.

Results: Renal IRG1 levels were reduced in two diabetic models. STZ+HFD-treated Irg1 knockout mice exhibited aggravated renal tubular injury and worsened renal function. Treatment with 4-OI lowered urinary albumin-to-creatinine ratio and blood urea nitrogen levels, and restored renal histological changes in db/db mice. It improved mitochondrial damage, increased expressions of peroxisome-proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitochondrial transcription factor A (TFAM) in the renal cortex of db/db mice. These were confirmed in vitro; 4-OI improved high glucose-induced abnormal mitochondrial morphology and TFAM expression in HK-2 cells, effects that were inhibited by PGC-1α silencing. Moreover, 4-OI reduced the number of apoptotic cells in the renal cortex of db/db mice. Further study showed that 4-OI increased renal Nrf2 expression and decreased oxidative stress levels in db/db mice. In HK-2 cells, 4-OI decreased high glucose-induced mitochondrial ROS production, which was reversed by Nrf2 silencing. Nrf2 depletion also inhibited 4-OI-mediated regulation of PGC-1α, TFAM, and mitochondrial apoptotic protein expressions.

Conclusions: 4-OI attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis.

RBBP6-Mediated ERRα Degradation Contributes to Mitochondrial Injury in Renal Tubular Cells in Diabetic Kidney Disease

Diabetic Kidney Disease (DKD), a major precursor to end-stage renal disease, involves mitochondrial dysfunction in proximal renal tubular cells (PTCs), contributing to its pathogenesis. Estrogen-related receptor α (ERRα) is essential for mitochondrial integrity in PTCs, yet its regulation in DKD is poorly understood. This study investigates ERRα expression and its regulatory mechanisms in DKD, assessing its therapeutic potential. Using genetic, biochemical, and cellular approaches, ERRα expression Was examined in human DKD specimens and DKD mouse models. We identified the E3 ubiquitin ligase retinoblastoma binding protein 6 (RBBP6) as a regulator of ERRα, promoting its degradation through K48-linked polyubiquitination at the K100 residue. This degradation pathway significantly contributed to mitochondrial injury in PTCs of DKD models. Notably, conditional ERRα overexpression or RBBP6 inhibition markedly reduced mitochondrial damage in diabetic mice, highlighting ERRα's protective role in maintaining mitochondrial integrity. The interaction between RBBP6 and ERRα opens new therapeutic avenues, suggesting that modulating RBBP6-ERRα interactions could be a strategy for preserving mitochondrial function and slowing DKD progression.

CircPWWP2A promotes renal interstitial fibrosis through modulating miR-182/ROCK1 axis

Renal fibrosis is a long-term and progressively worsening condition that impacts kidney function during aging and in the context of chronic kidney disease (CKD). CKD and renal fibrosis affect approximately 10% of the global population and are prevalent in about half of individuals over the age of 70. Despite ongoing research, the mechanisms underlying renal fibrosis are still not well understood, and there is currently a lack of effective treatments available. In the present study, we demonstrated a significant increase of circPWWP2A in renal tubular cells both in vivo and in vitro models of renal fibrosis. Suppressing circPWWP2A has the potential to reduce mitochondrial dysfunction and the production of mitochondrial reactive oxygen species (mtROS), ultimately leading to the inhibition of renal fibrosis. Whereas, supplementation of circPWWP2A led to more serve mitochondrial dysfunction, mtROS production and renal fibrosis. Mechanistically, we found the expression of circPWWP2A was negatively correlated with the expression of miR-182. And we further confirmed miR-182 was the direct target of circPWWP2A by dual-luciferase reporter assay and RIP assay. Then, we found miR-182 suppressed the expression of ROCK1 in both in vitro and in vivo models of renal fibrosis. Luciferase microRNA target reporter assay further indicated ROCK1 as a direct target of miR-182. Knockdown of ROCK1 inhibits renal fibrosis and mitochondrial dysfunction, suggesting ROCK1 not only served as an injurious role in mitochondrial homeostasis but also a pro-fibrotic factor in CKD. Taking together, our findings suggest that circPWWP2A may promote renal interstitial fibrosis by modulating miR-182/ROCK1-mediated mitochondrial dysfunction.

M6A RNA Methylation-Mediated TUG1 Stability Maintains Mitochondrial Homeostasis during Kidney Aging by Epigenetically Regulating PGC1-α Expression

Background: Aging is a significant risk factor for the increased incidence of acute kidney injury and chronic kidney disease, posing significant challenges to global public health. The role of N6-methyladenosine (m6A) in the development of chronic kidney disease has been reported, but the regulatory mechanism of m6A in kidney aging remains unclear. Results: In this study, we identified a long noncoding RNA (lncRNA), called taurine up-regulated 1 (TUG1), which exhibited a significantly decreased level of m6A modification in human aged kidney through the m6A-lncRNA epitranscriptome microarray. Bioinformatics analysis and machine learning predicted that TUG1 had potentially strong interaction with PGC1-α. RNA immunoprecipitation and chromatin immunoprecipitation analysis showed that TUG1 promoted proliferator-activated receptor γ coactivator-1α (PGC1-α) expression by directly interacting with its TUG-1 binding element region, thereby impacting mitochondrial quality control (MQC), cellular senescence, and renal fibrosis. Silencing the RNA m6A methylase methyltransferase 14 (METTL14) or the reader protein insulin-like growth factor 2 mRNA-binding proteins (IGF2BP2) resulted in the weakened stability of lncRNA TUG1, contributing to an imbalance in MQC. Conclusion: Our study demonstrated that the m6A modification and stability of TUG1 were mediated by METTL14 in an IGF2BP2-dependent manner, and modulate the mitochondrial homeostasis in kidney aging by direct targeting PGC-1α. These findings provide a new perspective on potential therapeutic targets for kidney aging. Antioxid. Redox Signal. 41, 993-1013.

Role of mitochondria in renal ischemia-reperfusion injury

Acute kidney injury (AKI) induced by renal ischemia-reperfusion injury (IRI) has a high morbidity and mortality, representing a worldwide problem. The kidney is an essential organ of metabolism that has high blood perfusion and is the second most mitochondria-rich organ after the heart because of the high ATP demands of its essential functions of nutrient reabsorption, acid-base and electrolyte balance, and hemodynamics. Thus, these energy-intensive cells are particularly vulnerable to mitochondrial dysfunction. As the bulk of glomerular ultrafiltrate reabsorption by proximal tubules occurs via active transport, the mitochondria of proximal tubules must be equipped for detecting and responding to fluctuations in energy availability to guarantee efficient basal metabolism. Any insults to mitochondrial quality control mechanisms may lead to biological disruption, blocking the clearance of damaged mitochondria and resulting in morphological change and tissue dysfunction. Extensive research has shown that mitochondria have pivotal roles in acute kidney disease, so in this article, we discuss the role of mitochondria, their dynamics and mitophagy in renal ischemia-reperfusion injury.

Human Umbilical Cord Mesenchymal Stem Cells Alleviate Diabetic Nephropathy by Inhibiting Ferroptosis via the JNK/KEAP1/NRF2 Signaling Pathway

Aims: Diabetic nephropathy (DN) is a major cause of end-stage renal disease, with no therapeutic interventions available to control its progression. Ferroptosis, an iron-dependent regulated cell death characterized by lipid peroxidation, plays a pivotal role in the pathogenesis of DN. Human umbilical cord mesenchymal stem cells (hUCMSCs) are an effective treatment modality for DN; however, the underlying mechanism of action remains unclear. The aim of the present study was to investigate whether hUCMSCs alleviate DN via inhibiting ferroptosis and its molecular mechanisms in type 2 diabetic mice and high-glucose and palmitate-stimulated human renal tubular epithelial cell (HK-11) models. Results: Our findings revealed that hUCMSCs improved the renal structure and function and tubular injuries. HUCMSC treatment can inhibit ferroptosis by decreasing iron content, reducing reactive oxygen species, malondialdehyde and 4-hydroxynonenal generation, decreasing the expression of positive ferroptosis mediator transferrin receptor 1 and long-chain acyl-CoA synthetase 4, and enhancing the expression of negative ferroptosis mediators (i.e., ferritin heavy chain, glutathione peroxidase 4, and system Xc-cystine/glutamate reverse transporter). Mechanistically, hUCMSC treatment inhibited c-Jun N-terminal kinase (JNK) and Kelch-like ECH-associated protein 1 (KEAP1) activation while increasing the expression of nuclear factor erythroid 2-related factor 2 (NRF2). Furthermore, pretreatment of HK-11 cells with NRF2 siRNA, the JNK inhibitor SP600125, or the JNK agonist anisomycin demonstrated the regulation of the JNK/KEAP1/NRF2 signaling pathway by hUCMSCs. Innovation and Conclusion: HUCMSCs inhibit ferroptosis in DN via the JNK/KEAP1/NRF2 signaling pathway, providing a new perspective and scientific evidence for treating DN. Antioxid. Redox Signal. 00, 000-000.

TFAM and Mitochondrial Protection in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a significant complication of diabetes and a major cause of end-stage renal disease. Affecting around 40% of diabetic patients, DKD poses substantial economic burdens due to its prevalence worldwide. The primary clinical features of DKD include the leakage of proteins into the urine, altered glomerular filtration, and an increased risk of cardiovascular diseases. Current treatments focus on managing hypertension and hyperglycemia to slow the progression of DKD. These include the use of SGLT2 inhibitors to control blood sugar and ACE inhibitors to reduce blood pressure. Despite these measures, current treatments do not cure DKD and fail to address its underlying causes. Emerging research highlights mitochondrial dysfunction as a pivotal factor in DKD progression. The kidneys' high energy requirements make them particularly susceptible to disturbances in mitochondrial function. In DKD, mitochondrial damage leads to reduced energy production and increased oxidative stress, exacerbating tissue damage. Mitochondrial DNA (mtDNA) damage is a key aspect of this dysfunction, with studies suggesting that changes in mtDNA copy number can serve as biomarkers for the progression of the disease. Efforts to target mitochondrial dysfunction are gaining traction as a potential therapeutic strategy. This includes promoting mitochondrial health through pharmacological and lifestyle interventions aimed at enhancing mitochondrial function and reducing oxidative stress. Such approaches could lead to more effective treatments that directly address the DKD.

Supplemented Gegen Qinlian Decoction Formula attenuates podocyte mitochondrial fission and renal fibrosis in diabetic kidney disease by inhibiting TNF-α-mediated necroptosis, compared with empagliflozin

ETHNOPHARMACOLOGICAL RELEVANCE

Recently, podocyte mitochondrial dysfunction and necroptosis have been shown to play critical roles in renal fibrosis (RF) in diabetic kidney disease (DKD); however, these conditions lack effective treatment. In China, the supplemented Gegen Qinlian Decoction Formula (SGQDF), which originates from the classical prescription Gegen Qinlian Decoction, has been widely used to treat patients with DKD. However, it remains unclear whether SGQDF alleviates podocyte injury-associated RF in patients with DKD.

AIM OF STUDY

This study aimed to clarify the therapeutic effects of SGQDF compared with those of empagliflozin (EMPA) on podocyte mitochondrial fission and RF in DKD and its necroptosis-related mechanisms.

MATERIALS AND METHODS

Modified DKD rat models were developed through a combination of uninephrectomy, streptozotocin administration through intraperitoneal injection, and exposure to a high-fat diet. Following RF formation, the DKD rat models received either a high dose of SGQDF (H-SGQDF), a low dose of SGQDF (L-SGQDF), EMPA, or vehicle for 4 weeks. In our in vitro study, we subjected cultured murine podocytes to a high-glucose environment and various treatments including Mdivi-1, adalimumab, and necrostatin-1, with or without H-SGQDF or EMPA. SGQDF target prediction and molecular docking verification were performed. For the in vivo study, we focused on examining changes in the parameters associated with renal injury, RF, and oxidative stress (OS)-induced injuries in podocytes. Both in vivo and in vitro studies included an analysis of changes in podocyte mitochondrial fission, TNF-α-induced podocyte necroptosis, and the RIPK1/RIPK3/MLKL signaling pathway activation.

RESULTS

SGQDF improved renal injury markers, including body weight, blood glucose, serum creatinine, blood urea nitrogen, and urinary albumin, in a dose-dependent manner. The beneficial effects of H-SGQDF in vivo were greater than those of L-SGQDF alone in vivo. Interestingly, similar to EMPA, H-SGQDF ameliorated RF and reduced OS-induced podocyte injury in diabetic kidneys. Furthermore, TNF-α signaling was shown to be important in the network construction of "the SGQDF-component-target." Based on this, we also showed that the beneficial effects in vivo and in vitro of H-SGQDF were closely related to the improvement in mitochondrial dysfunction and the inhibition of TNF-α-induced necroptosis in podocytes.

CONCLUSION

In the present study, we showed that H-SGQDF, similar to EMPA, attenuates podocyte mitochondrial fission and RF, and that the underlying therapeutic mechanisms are closely related to inhibiting the activation of the RIPK1/RIPK3/MLKL signaling axis in diabetic kidneys. Our findings provide new pharmacological evidence for the application of H-SGQDF in the RF treatment of DKD.

Kidney Injury Evoked by Fine Particulate Matter: Risk Factor, Causation, Mechanism and Intervention Study

Fine particulate matter (PM2.5) is suggested to pose a severe risk to the kidneys by inducing functional degradation and chronic kidney diseases (CKD). This study aims to explore the nephrotoxicity of PM2.5 exposure and the underlying mechanism. Herein, based on the UK Biobank, it is found that per interquartile range (IQR) increase in PM2.5 is associated with a 6% (95% CI: 1%-11%), 7% (95% CI: 3%-11%), 9% (95% CI: 4%-13%), 11% (95% CI: 9%-13%), and 10% (95% CI: 8%-12%) increase in the risk of nephritis, hydronephrosis, kidney stone, acute renal failure, and CKD, respectively. In experimental study, noticeable kidney injury, which is the initiation of kidney diseases, is observed with PM2.5 exposure in C57BL/6N mice (n = 8), accompanied with oxidative stress, autophagy and pyroptosis. In vitro, HK-2 cells with PM2.5-stimulation exhibit tubulopathy, increased reactive oxygen species (ROS) generation and activated pyroptosis and autophagy. All changes are abolished by ROS scavenger of N-acetyl-L-cysteine (NAC) both in vivo and in vitro. In conclusion, the study provides evidence showing that PM2.5 exposure is associated with 5 kinds of kidney diseases by directly inducing nephrotoxicity, in which ROS may be the potential target by triggering autophagy and pyroptosis.

TRPC6-Calpain-1 Axis Promotes Tubulointerstitial Inflammation by Inhibiting Mitophagy in Diabetic Kidney Disease

Introduction

Renal tubulointerstitial inflammation represents an effective indicator for predicting the progression of diabetic kidney disease (DKD). Mitophagy abnormality is 1 of the most important factors involved in tubule injury. However, the exact molecular mechanism underlying mitophagy abnormality-mediated tubulointerstitial inflammation in DKD remains poorly understood.

Methods

In this study, a streptozotocin-induced DKD mouse model was established and HK-2 cells treated with high glucose (HG) served as an in vitro model. Tubular mitophagy was regulated through pharmacological urolithin A (UA) administration. The functional effect of the transient receptor potential cation channel, subfamily C, member 6 (TRPC6) was explored using genetic interventions in vivo and in vitro.

Results

We found that renal tubulointerstitial inflammation in DKD was closely associated with mitophagy inhibition, which was mediated by disturbance of PINK1/Parkin pathway. Mitophagy activation significantly attenuated tubular injury and tubulointerstitial inflammation. Further, it was found that TRPC6 was markedly increased in DKD and played an essential role in mitophagy inhibition by activating calpain-1. Knockdown of Trpc6 partially reversed mitophagy abnormality and consequently attenuated tubular injury and tubulointerstitial inflammation in vivo and in vitro. Finally, we found that tubular TRPC6-mediated mitophagy inhibition was blocked with BAPTA (a specific Ca2+ chelator) or calpeptin (a specific calpain-1 inhibitor).

Conclusion

Our study reveals that TRPC6-calpain-1 axis promotes tubulointerstitial inflammation in DKD by inhibiting mitophagy.

Targeting TGR5 to mitigate liver fibrosis: Inhibition of hepatic stellate cell activation through modulation of mitochondrial fission

Chronic hepatitis B virus (HBV) infection continues to be a prominent cause of liver fibrosis and end-stage liver disease in China, necessitating the development of effective therapeutic strategies. This study investigated the potential of targeting TGR5 to alleviate liver fibrosis by impeding the activation of hepatic stellate cells (HSCs), which play a pivotal role in fibrotic progression. Using the human hepatic stellate cell line LX-2 overexpressing hepatitis B virus X protein (HBX), this study revealed that TGR5 activation through INT-777 inhibits HBX-induced LX-2 cell activation, thereby ameliorating liver fibrosis, which is associated with the attenuation of mitochondrial fission and introduces a novel regulatory pathway in liver fibrosis. Additional experiments with mitochondrial fission inducers and inhibitors confirm the crucial role of mitochondrial dynamics in TGR5-mediated effects. In vivo studies using TGR5 knockout mice substantiate these findings, demonstrating exacerbated fibrosis in the absence of TGR5 and its alleviation with the mitochondrial fission inhibitor Mdivi-1. Overall, this study provides insights into TGR5-mediated regulation of liver fibrosis through the modulation of mitochondrial fission in HSCs, suggesting potential therapeutic strategies for liver fibrosis intervention.

Dapagliflozin attenuates AKI to CKD transition in diabetes by activating SIRT3/PGC1-α signaling and alleviating aberrant metabolic reprogramming

BACKGROUND

Patients with diabetes are prone to acute kidney injury (AKI) with a high mortality rate, poor prognosis, and a higher risk of progression to chronic kidney disease than non-diabetic patients.

METHODS

Streptozotocin (STZ)-treated type 1 and db/db type 2 diabetes model were established, AKI model was induced in mice by ischemia-reperfusion injury(IRI). Mouse proximal tubular cell cells were subjected to high glucose and hypoxia-reoxygenation in vitro. Transcriptional RNA sequencing was performed for clustering analysis and target gene screening. Renal structural damage was determined by histological staining, whereas creatinine and urea nitrogen levels were used to measure renal function.

RESULTS

Deteriorated renal function and renal tissue damage were observed in AKI mice with diabetic background. RNA sequencing showed a decrease in fatty acid oxidation (FAO) pathway and an increase in abnormal glycolysis. Treatment with Dapa, Sitagliptin(a DPP-4 inhibitor)and insulin reduced blood glucose levels in mice, and improved renal function. However, Dapa had a superior therapeutic effect and alleviated aberrant FAO and glycosis. Dapa reduced cellular death in cultured cells under high glucose hypoxia-reoxygenation conditions, alleviated FAO dysfunction, and reduced abnormal glycolysis. RNA sequencing showed that SIRT3 expression was reduced in diabetic IRI, which was largely restored by Dapa intervention. 3-TYP, a SIRT3 inhibitor, reversed the renal protective effects of Dapa and mediated abnormal FAO and glycolysis in mice and tubular cells.

CONCLUSION

Our study provides experimental evidence for the use of Dapa as a means to reduce diabetic AKI by ameliorating metabolic reprogramming in renal tubular cells.

Interplay between the Redox System and Renal Tubular Transport

The kidney plays a critical role in maintaining the homeostasis of body fluid by filtration of metabolic wastes and reabsorption of nutrients. Due to the overload, a vast of energy is required through aerobic metabolism, which inevitably leads to the generation of reactive oxygen species (ROS) in the kidney. Under unstressed conditions, ROS are counteracted by antioxidant systems and maintained at low levels, which are involved in signal transduction and physiological processes. Accumulating evidence indicates that the reduction-oxidation (redox) system interacts with renal tubular transport. Redox imbalance or dysfunction of tubular transport leads to renal disease. Here, we discuss the ROS and antioxidant systems in the kidney and outline the metabolic dysfunction that is a common feature of renal disease. Importantly, we describe the key molecules involved in renal tubular transport and their relationship to the redox system and, finally, summarize the impact of their dysregulation on the pathogenesis and progression of acute and chronic kidney disease.

Targeted mitochondrial nanomaterials in biomedicine: Advances in therapeutic strategies and imaging modalities

Mitochondria, pivotal organelles crucial for energy generation, apoptosis regulation, and cellular metabolism, have spurred remarkable advancements in targeted material development. This review surveys recent breakthroughs in targeted mitochondrial nanomaterials, illuminating their potential in drug delivery, disease management, and biomedical imaging. This review approaches from various application perspectives, introducing the specific applications of mitochondria-targeted materials in cancer treatment, probes and imaging, and diseases treated with mitochondria as a therapeutic target. Addressing extant challenges and elucidating potential therapeutic mechanisms, it also outlines future development trajectories and obstacles. By comprehensively exploring the diverse applications of targeted mitochondrial nanomaterials, this review aims to catalyze innovative treatment modalities and diagnostic approaches in medical research. STATEMENT OF SIGNIFICANCE: This review presents the latest advancements in mitochondria-targeted nanomaterials for biomedical applications, covering diverse fields such as cancer therapy, bioprobes, imaging, and the treatment of various systemic diseases. The novelty and significance of this work lie in its systematic analysis of the intricate relationship between mitochondria and different diseases, as well as the ingenious design strategies employed to harness the therapeutic potential of nanomaterials. By providing crucial insights into the development of mitochondria-targeted nanomaterials and their applications, this review offers a valuable resource for researchers working on innovative treatment modalities and diagnostic approaches. The scientific impact and interest to the readership lie in the identification of promising avenues for future research and the potential for clinical translation of these cutting-edge technologies.

Biomarkers of Arginine Methylation in Diabetic Nephropathy: Novel Insights from Bioinformatics Analysis

Background

Diabetic nephropathy (DN) is a severe complication of diabetes influenced by arginine methylation. This study aimed to elucidate the role of protein arginine methylation-related genes (PRMT-RGs) in DN and identify potential biomarkers.

Methods

Differentially expressed genes in two GEO datasets (GSE30122 and GSE104954) were integrated with 9 PRMT-RGs. Candidate genes were identified using WGCNA and differential expression analysis, then screened using support vector machine-recursive feature elimination and least absolute shrinkage and selection operator. Biomarkers were defined as genes with consistent differential expression across both datasets. Regulatory networks were constructed using the miRNet and Network Analyst databases. Gene set enrichment analysis was performed to identify the signaling pathways in which the biomarkers were enriched in DN. Different immune cells in DN were identified using immune infiltration analysis. Meanwhile, drug prediction and molecular docking identified potential DN therapies. Finally, qRT-PCR and immunohistochemistry validated two biomarkers in STZ-induced DN mice and DN patients.

Results

Two biomarkers (FAM98A and FAM13B) of DN were identified in this study. The molecular regulatory network revealed that FAM98A and FAM13B were co-regulated by 6 microRNAs and 1 transcription factor and were enriched in signaling pathways. Immune infiltration and correlation analyses revealed that FAM98A and FAM13B were involved in developing DN along with PRMT-RGs and immune cells. The expression levels of Fam98a and Fam13b were significantly upregulated in the kidneys of DN mice revealed by qRT-PCR analysis. The expression levels of FAM98A were significantly upregulated in the kidneys of DN patients revealed by immunohistochemistry staining. Molecular docking showed that estradiol and rotenone exerted potential therapeutic effects on DN by targeting FAM98A.

Conclusion

Comprehensive bioinformatics analysis revealed that FAM98A and FAM13B were potential DN biomarkers correlated with PRMT-RGs and immune cells. This study provided useful insights for elucidating the molecular mechanisms and developing targeted therapy for DN.

LONP1 alleviates ageing-related renal fibrosis by maintaining mitochondrial homeostasis

Mitochondrial dysfunction is a pivotal event contributing to the development of ageing-related kidney disorders. Lon protease 1 (LONP1) has been reported to be responsible for ageing-related renal fibrosis; however, the underlying mechanism(s) of LONP1-driven kidney ageing with respect to mitochondrial disturbances remains to be further explored. The level of LONP1 was tested in the kidneys of aged humans and mice. Renal fibrosis and mitochondrial quality control were confirmed in the kidneys of aged mice. Effects of LONP1 silencing or overexpression on renal fibrosis and mitochondrial quality control were explored. In addition, N6-methyladenosine (m6A) modification and methyltransferase like 3 (METTL3) levels, the relationship between LONP1 and METTL3, and the impacts of METTL3 overexpression on mitochondrial functions were confirmed. Furthermore, the expression of insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) and the regulatory effects of IGF2BP2 on LONP1 were confirmed in vitro. LONP1 expression was reduced in the kidneys of aged humans and mice, accompanied by renal fibrosis and mitochondrial dysregulation. Overexpression of LONP1 alleviated renal fibrosis and maintained mitochondrial homeostasis, while silencing of LONP1 had the opposite effect. Impaired METTL3-m6A signalling contributed at least in part to ageing-induced LONP1 modification, reducing subsequent degradation in an IGF2BP2-dependent manner. Moreover, METTL3 overexpression alleviated proximal tubule cell injury, preserved mitochondrial stability, inhibited LONP1 degradation, and protected mitochondrial functions. LONP1 mediates mitochondrial function in kidney ageing and that targeting LONP1 may be a potential therapeutic strategy for improving ageing-related renal fibrosis.

Astragaloside IV protects renal tubular epithelial cells against oxidative stress-induced injury by upregulating CPT1A-mediated HSD17B10 lysine succinylation in diabetic kidney disease

Tubular injury and oxidative stress are involved in the pathogenesis of diabetic kidney disease (DKD). Astragaloside IV (ASIV) is a natural antioxidant. The effects and underlying molecular mechanisms of ASIV on DKD have not been elucidated. The db/db mice and high-glucose-stimulated HK2 cells were used to evaluate the beneficial effects of ASIV in vivo and in vitro. Succinylated proteomics was used to identify novel mechanisms of ASIV against DKD and experimentally further validated. ASIV alleviated renal dysfunction and proteinuria, downregulated fasting blood glucose, and upregulated insulin sensitivity in db/db mice. Meanwhile, ASIV alleviated tubular injury, oxidative stress, and mitochondrial dysfunction in vivo and in vitro. Mechanistically, ASIV reversed downregulated 17beta-hydroxysteroid dehydrogenase type 10 (HSD17B10) lysine succinylation by restoring carnitine palmitoyl-transferase1alpha (Cpt1a or CPT1A) activity in vivo and in vitro. Molecular docking and cell thermal shift assay revealed that ASIV may bind to CPT1A. Molecular dynamics simulations demonstrated K99 succinylation of HSD17B10 maintained mitochondrial RNA ribonuclease P (RNase P) stability. The K99R mutation of HSD17B10 induced oxidative stress and disrupted its binding to CPT1A or mitochondrial ribonuclease P protein 1 (MRPP1). Importantly, ASIV restored the interaction between HSD17B10 and MRPP1 in vivo and in vitro. We also demonstrated that ASIV reversed high-glucose-induced impaired RNase P activity in HK2 cells, which was suppressed upon K99R mutation of HSD17B10. These findings suggest that ASIV ameliorates oxidative stress-associated proximal tubular injury by upregulating CPT1A-mediated K99 succinylation of HSD17B10 to maintain RNase P activity.

RUNX3 alleviates mitochondrial dysfunction and tubular damage by inhibiting TLR4/NF-κB signalling pathway in diabetic kidney disease

AIM

The impaired function of tubular mitochondria is critical in diabetic kidney disease (DKD) progression. RUNX3 is down-regulated in DKD models. We intend to explore the effects of RUNX3 on mitochondrial dysfunction and renal tubule injury in DKD and related mechanisms.

METHODS

The development of diabetes models involved injecting mice with streptozotocin while treating HK-2 cells with high glucose (HG). By using immunohistochemical techniques, the renal localizations of RUNX3 were identified. Levels of adenosine triphosphate (ATP), mitochondrial membrane potential, and biochemical index were detected by appropriate kits. Reactive oxygen species (ROS) generation was assessed with dihydroethidium and MitoSOX Red staining. Apoptosis was assessed by flow cytometry and TUNEL. RUNX3 ubiquitination was measured.

RESULTS

RUNX3 was mainly present in renal tubules. Overexpressing RUNX3 increased Mfn2, Mfn1, ATP levels, and mitochondrial membrane potential, reduced Drp1 and ROS levels and cell apoptosis, as well as Cyt-C release into the cytoplasm. RUNX3 overexpression displayed a reduction in urinary albumin to creatinine ratio, Hemoglobin A1c, serum creatinine, and blood urea nitrogen. Overexpressing TLR4 attenuated the inhibitory effect of RUNX3 overexpression on mitochondrial dysfunction and cell apoptosis. HG promoted RUNX3 ubiquitination and SMURF2 expression. RUNX3 knockdown cancelled the inhibitory effect of SMURF2 on mitochondrial dysfunction and cell apoptosis.

CONCLUSION

SMURF2 interference inhibits RUNX3 ubiquitination and TLR4/NF-κB signalling pathway, thereby alleviating renal tubule injury.

Inhibition of PKC-δ retards kidney fibrosis via inhibiting cGAS-STING signaling pathway in mice

Kidney fibrosis is considered to be the ultimate aggregation pathway of chronic kidney disease (CKD), but its underlying mechanism remains elusive. Protein kinase C-delta (PKC-δ) plays critical roles in the control of growth, differentiation, and apoptosis. In this study, we found that PKC-δ was highly upregulated in human biopsy samples and mouse kidneys with fibrosis. Rottlerin, a PKC-δ inhibitor, alleviated unilateral ureteral ligation (UUO)-induced kidney fibrosis, inflammation, VDAC1 expression, and cGAS-STING signaling pathway activation. Adeno-associated virus 9 (AAV9)-mediated VDAC1 silencing or VBIT-12, a VDAC1 inhibitor, attenuated renal injury, inflammation, and activation of cGAS-STING signaling pathway in UUO mouse model. Genetic and pharmacologic inhibition of STING relieved renal fibrosis and inflammation in UUO mice. In vitro, hypoxia resulted in PKC-δ phosphorylation, VDAC1 oligomerization, and activation of cGAS-STING signaling pathway in HK-2 cells. Inhibition of PKC-δ, VDAC1 or STING alleviated hypoxia-induced fibrotic and inflammatory responses in HK-2 cells, respectively. Mechanistically, PKC-δ activation induced mitochondrial membrane VDAC1 oligomerization via direct binding VDAC1, followed by the mitochondrial DNA (mtDNA) release into the cytoplasm, and subsequent activated cGAS-STING signaling pathway, which contributed to the inflammation leading to fibrosis. In conclusion, this study has indicated for the first time that PKC-δ is an important regulator in kidney fibrosis by promoting cGAS-STING signaling pathway which mediated by VDAC1. PKC-δ may be useful for treating renal fibrosis and subsequent CKD.

Roles of Mitochondrial Dysfunction in Diabetic Kidney Disease: New Perspectives from Mechanism to Therapy

Diabetic kidney disease (DKD) is a common microvascular complication of diabetes and the main cause of end-stage renal disease around the world. Mitochondria are the main organelles responsible for producing energy in cells and are closely involved in maintaining normal organ function. Studies have found that a high-sugar environment can damage glomeruli and tubules and trigger mitochondrial dysfunction. Meanwhile, animal experiments have shown that DKD symptoms are alleviated when mitochondrial damage is targeted, suggesting that mitochondrial dysfunction is inextricably linked to the development of DKD. This article describes the mechanisms of mitochondrial dysfunction and the progression and onset of DKD. The relationship between DKD and mitochondrial dysfunction is discussed. At the same time, the progress of DKD treatment targeting mitochondrial dysfunction is summarized. We hope to provide new insights into the progress and treatment of DKD.

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.

Advance in Iron Metabolism, Oxidative Stress and Cellular Dysfunction in Experimental and Human Kidney Diseases

Kidney diseases pose a significant global health issue, frequently resulting in the gradual decline of renal function and eventually leading to end-stage renal failure. Abnormal iron metabolism and oxidative stress-mediated cellular dysfunction facilitates the advancement of kidney diseases. Iron homeostasis is strictly regulated in the body, and disturbance in this regulatory system results in abnormal iron accumulation or deficiency, both of which are associated with the pathogenesis of kidney diseases. Iron overload promotes the production of reactive oxygen species (ROS) through the Fenton reaction, resulting in oxidative damage to cellular molecules and impaired cellular function. Increased oxidative stress can also influence iron metabolism through upregulation of iron regulatory proteins and altering the expression and activity of key iron transport and storage proteins. This creates a harmful cycle in which abnormal iron metabolism and oxidative stress perpetuate each other, ultimately contributing to the advancement of kidney diseases. The crosstalk of iron metabolism and oxidative stress involves multiple signaling pathways, such as hypoxia-inducible factor (HIF) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways. This review delves into the functions and mechanisms of iron metabolism and oxidative stress, along with the intricate relationship between these two factors in the context of kidney diseases. Understanding the underlying mechanisms should help to identify potential therapeutic targets and develop novel and effective therapeutic strategies to combat the burden of kidney diseases.

Mitochondrial dysfunction in the pathophysiology of renal diseases

Mitochondria are essential organelles in the human body, serving as the metabolic factory of the whole organism. When mitochondria are dysfunctional, it can affect all organs of the body. The kidney is rich in mitochondria, and its function is closely related to the development of kidney diseases. Studying the relationship between mitochondria and kidney disease progression is of great interest. In the past decade, scientists have made inspiring progress in investigating the role of mitochondria in the pathophysiology of renal diseases. This article discusses various mechanisms for maintaining mitochondrial quality, including mitochondrial energetics, mitochondrial biogenesis, mitochondrial dynamics, mitochondrial DNA repair, mitochondrial proteolysis and the unfolded protein response, mitochondrial autophagy, mitochondria-derived vesicles, and mitocytosis. The article also highlights the cross talk between mitochondria and other organelles, with a focus on kidney diseases. Finally, the article concludes with an overview of mitochondria-related clinical research.

Apelin‑13 reduces high glucose‑induced mitochondrial dysfunction in cochlear hair cells by inhibiting endoplasmic reticulum stress

The complex manifestation of diabetic hearing loss and the relative inaccessibility of the inner ear contribute to the lack of research. The present study aimed to reveal the role of Apelin-13, a critical regulator of lipid metabolism, in diabetes-induced hearing loss. Cochlear hair cells treated with high glucose (HG) were adopted as an in vitro research model, and the impacts of Apelin-13 on cellular oxidative stress, apoptosis, mitochondrial dysfunction and endoplasmic reticulum (ER) stress were determined. In addition, cells were treated with the ER stress agonist tunicamycin to further explore its potential role in the regulatory effects of Apelin-13. Apelin-13 inhibited oxidative stress and apoptosis in the HG-induced cells. Additionally, Apelin-13 elevated mitochondrial membrane potential and ATP production, whereas it reduced mitochondrial reactive oxygen species levels. The levels of ER stress-related proteins exhibited a downward trend in response to Apelin-13. By contrast, tunicamycin reversed the effects of Apelin-13 on the aforementioned aspects, suggesting the role of ER stress in the regulatory effects of Apelin-13. In conclusion, the present study elucidated the protective role of Apelin-13 in ameliorating HG-induced mitochondrial functional impairment in cochlear hair cells by inhibiting ER stress.

The case for a ketogenic diet in the management of kidney disease

Ketogenic diets have been widely used for weight loss and are increasingly used in the management of type 2 diabetes. Despite evidence that ketones have multiple positive effects on kidney function, common misconceptions about ketogenic diets, such as high protein content and acid load, have prevented their widespread use in individuals with impaired kidney function. Clinical trial evidence focusing on major adverse kidney events is sparse. The aim of this review is to explore the effects of a ketogenic diet, with an emphasis on the pleiotropic actions of ketones, on kidney health. Given the minimal concerns in relation to the potential renoprotective effects of a ketogenic diet, future studies should evaluate the safety and efficacy of ketogenic interventions in kidney disease.