Background: Diabetic kidney disease (DKD) is a common complication of diabetes that is clinically characterized by progressive albuminuria due to glomerular destruction. The etiology of DKD is multifactorial, and numerous studies have demonstrated that cellular senescence plays a significant role in its pathogenesis, but the specific mechanism requires further investigation.Methods: This study utilized 5 datasets comprising 144 renal samples from the Gene Expression Omnibus (GEO) database. We obtained cellular senescence-related pathways from the Molecular Signatures Database and evaluated the activity of senescence pathways in DKD patients using the Gene Set Enrichment Analysis (GSEA) algorithm. Furthermore, we identified module genes related to cellular senescence pathways through Weighted Gene Co-Expression Network Analysis (WGCNA) algorithm and used machine learning algorithms to screen for hub genes related to senescence. Subsequently, we constructed a cellular senescence-related signature (SRS) risk score based on hub genes using the Least Absolute Shrinkage and Selection Operator (LASSO), and verified mRNA levels of hub genes by RT-PCR in vivo. Finally, we validated the relationship between the SRS risk score and kidney function, as well as their association with mitochondrial function and immune infiltration.Results: The activity of cellular senescence-related pathways was found to be elevated among DKD patients. Based on 5 hub genes (LIMA1, ZFP36, FOS, IGFBP6, CKB), a cellular senescence-related signature (SRS) was constructed and validated as a risk factor for renal function decline in DKD patients. Notably, patients with high SRS risk scores exhibited extensive inhibition of mitochondrial pathways and upregulation of immune cell infiltration.Conclusion: Collectively, our findings demonstrated that cellular senescence is involved in the process of DKD, providing a novel strategy for treating DKD.

Background: Oxidative stress is the hallmark of diabetic encephalopathy, which may be caused by hyperglycaemic toxicity. We aimed to discover pharmacologic targets to restore redox homeostasis. We identified the transcription factor Nrf2 as such a target. Methods: HT22 cells were cultured in 25 or 50 mM d-glucose with various concentrations of sulforaphane (SFN) (from 1.25 to 5.0 μM). Cell viability was tested with the Cell Counting Kit-8 assay. Reactive oxygen species (ROS) production was detected with an inverted fluorescence microscope using the dichlorodihydrofluorescein-diacetate fluorescent probe. The expression of NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1) and nuclear factor-κB (NF-κB) at the mRNA and protein levels was detected by reverse transcription quantitative polymerase chain reaction and western blotting. Result: We found that a high glucose concentration (50 mM) increased the generation of ROS, downregulated the expression of Nrf2/HO-1 and upregulated the expression of NF-κB. Moreover, HT22 cell viability significantly decreased after culture in high-glucose medium for 24, 48 and 72 h, whereas the activation of the Nrf2/HO-1 pathway using a pharmacological Nrf2 activator abrogated this high-glucose-induced toxicity. Conclusion: This study suggests that the activation of the Nrf2–ARE signalling pathway might be a therapeutic target for the treatment of diabetic encephalopathy.

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide. Renal tubular epithelial cell apoptosis and tubular atrophy have been recognized as indicators of the severity and progression of DKD, while the mechanism remains elusive. Tumor necrosis factor receptor-associated protein 1 (TRAP1) plays critical roles in apoptosis. The aim of this study was to investigate the protective role TRAP1 plays in DKD and to study the potential underlying mechanisms. TRAP1 expression was decreased, and mitochondria were injured in NRK-52e cells under high-glucose (HG) conditions. The overexpression of TRAP1 ameliorated HG-induced apoptosis, increased cell viability, maintained mitochondrial morphology, adenosine triphosphate (ATP) levels, and mitochondrial membrane potential (MMP), and buffered oxidative stress, whereas TRAP1 knockdown aggravated these effects. The protective effects of TRAP1 may be exerted via the inhibition of mitochondrial permeability transition pore (mPTP) opening, and the damage caused by TRAP1 knockdown can be partially reversed by treatment with the mPTP opening inhibitor cyclosporin A (CsA). In vivo, TRAP1 expression upregulation by AAV2/9 injection prevented renal dysfunction, ameliorated histopathological changes, maintained mitochondrial morphology and function, and reduced apoptosis and reactive oxygen species (ROS) in STZ-treated DKD rats. Thus, our results suggest that TRAP1 ameliorates diabetes-induced renal injury by preventing abnormal mPTP opening and maintaining mitochondrial structure and function, which may be treated as a potential target for DKD treatment.

Background: The senescence of renal tubular epithelial cells (RTECs) is crucial in the progression of diabetic kidney disease (DKD). Accumulating evidence suggests a close association between insufficient mitophagy and RTEC senescence. Yeast mitochondrial escape 1-like 1 (YME1L), an inner mitochondrial membrane metalloprotease, maintains mitochondrial integrity. Its functions in DKD remain unclear. Here, we investigated whether YME1L can prevent the progression of DKD by regulating mitophagy and cellular senescence. Methods: We analyzed YME1L expression in renal tubules of DKD patients and mice, explored transcriptomic changes associated with YME1L overexpression in RTECs, and assessed its impact on RTEC senescence and renal dysfunction using an HFD/STZ-induced DKD mouse model. Tubule-specific overexpression of YME1L was achieved through the use of recombinant adeno-associated virus 2/9 (rAAV 2/9). We conducted both in vivo and in vitro experiments to evaluate the effects of YME1L overexpression on mitophagy and mitochondrial function. Furthermore, we performed LC–MS/MS analysis to identify potential protein interactions involving YME1L and elucidate the underlying mechanisms. Results: Our findings revealed a significant decrease in YME1L expression in the renal tubules of DKD patients and mice. However, tubule-specific overexpression of YME1L significantly alleviated RTEC senescence and renal dysfunction in the HFD/STZ-induced DKD mouse model. Moreover, YME1L overexpression exhibited positive effects on enhancing mitophagy and improving mitochondrial function both in vivo and in vitro. Mechanistically, our LC–MS/MS analysis uncovered a crucial mitophagy receptor, BCL2-like 13 (BCL2L13), as an interacting partner of YME1L. Furthermore, YME1L was found to promote the phosphorylation of BCL2L13, highlighting its role in regulating mitophagy. Conclusions: This study provides compelling evidence that YME1L plays a critical role in protecting RTECs from cellular senescence and impeding the progression of DKD. Overexpression of YME1L demonstrated significant therapeutic potential by ameliorating both RTEC senescence and renal dysfunction in the DKD mice. Moreover, our findings indicate that YME1L enhances mitophagy and improves mitochondrial function, potentially through its interaction with BCL2L13 and subsequent phosphorylation. These novel insights into the protective mechanisms of YME1L offer a promising strategy for developing therapies targeting DKD.