TRAP1 ameliorates renal tubulointerstitial fibrosis in mice with unilateral ureteral obstruction by protecting renal tubular epithelial cell mitochondria.

Mitochondrial dysfunction causes renal tubular epithelial cell injury and promotes cell apoptosis and renal tubulointerstitial fibrosis (TIF) progression. TNF receptor-associated protein 1 (TRAP1) is a molecular chaperone protein that is localized in mitochondria. It plays an important role in cell apoptosis; however, its functional mechanism in TIF remains unclear. In this study, we observed the effects of TRAP1 in renal tubular epithelial cell mitochondria in mice with unilateral ureteral obstruction and its function in cell apoptosis and TIF. Results show that TRAP1 could protect the mitochondrial structure in renal tubular epithelial cells; maintain the levels of mitochondrial membrane potential, ATP, and mitochondrial DNA copy number; inhibit reactive oxygen species production; stabilize the expression of the mitochondrial inner membrane protein mitofilin; reduce renal tubular epithelial cell apoptosis; and inhibit TIF. These results provide new theoretical foundations for additional understanding of the antifibrotic mechanism of TRAP1 in the kidney.-Chen, J.-F., Wu, Q.-S., Xie, Y.-X., Si, B.-L., Yang, P.-P., Wang, W.-Y., Hua, Q., He, Q. TRAP1 ameliorates renal tubulointerstitial fibrosis in mice with unilateral ureteral obstruction by protecting renal tubular epithelial cell mitochondria.

The role of mitofilin in left ventricular hypertrophy in hemodialysis patients.

Left ventricular hypertrophy (LVH) is a common abnormality in hemodialysis (HD) patients. Mitochondrial dysfunction contributes to the progression of LVH. As an inner mitochondrial membrane structural protein, mitofilin plays a key role in maintaining mitochondrial structure and function. The aim of this study was to investigate the relationship between mitofilin and LVH in HD patients. A total of 98 HD patients and 32 healthy controls were included in the study. Serum N-terminal proBNP (NT-proBNP), endothelin-1 (ET-1), and atrial natriuretic peptide (ANP) were examined. The protein level of mitofilin and the mitochondrial DNA (mtDNA) copy number were estimated in peripheral blood mononuclear cells (PBMCs). The left ventricle mass index (LVMI) was evaluated in all participants, and the interaction between these variables and the LVMI was assessed. The LVMI was positively correlated with the NT-proBNP, ET-1, and ANP levels, and it was negatively correlated with mtDNA copy number and mitofilin levels. Multiple regression analysis showed that the NT-proBNP, ET-1, and ANP levels as well as mitofilin levels and mtDNA copy number were associated with the LVMI. Although further research of these associations is needed, this result suggests that LVH may affect the levels of mitofilin in HD patients.

MicroRNA-630 alleviates inflammatory reactions in rats with diabetic kidney disease by targeting toll-like receptor 4.

BACKGROUND: Diabetic kidney disease (DKD) is a major complication of diabetes mellitus. Renal tubular epithelial cell (TEC) damage, which is strongly associated with the inflammatory response and mesenchymal trans-differentiation, plays a significant role in DKD; However, the precise molecular mechanism is unknown. The recently identified microRNA-630 (miR-630) has been hypothesized to be closely associated with cell migration, apoptosis, and autophagy. However, the association between miR-630 and DKD and the underlying mechanism remain unknown. AIM: To investigate how miR-630 affects TEC injury and the inflammatory response in DKD rats. METHODS: Streptozotocin was administered to six-week-old male rats to create a hyperglycemic diabetic model. In the second week of modeling, the rats were divided into control, DKD, negative control of lentivirus, and miR-630 overexpression groups. After 8 wk, urine and blood samples were collected for the kidney injury assays, and renal tissues were removed for further molecular assays. The target gene for miR-630 was predicted using bioinformatics, and the association between miR-630 and toll-like receptor 4 (TLR4) was confirmed using in vitro investigations and double luciferase reporter gene assays. Overexpression of miR-630 in DKD rats led to changes in body weight, renal weight index, basic blood parameters and histopathological changes. RESULTS: The expression level of miR-630 was reduced in the kidney tissue of rats with DKD (P < 0.05). The miR-630 and TLR4 expressions in rat renal TECs (NRK-52E) were measured using quantitative reverse transcription polymerase chain reaction. The mRNA expression level of miR-630 was significantly lower in the high-glucose (HG) and HG + mimic negative control (NC) groups than in the normal glucose (NG) group (P < 0.05). In contrast, the mRNA expression level of TLR4 was significantly higher in these groups (P < 0.05). However, miR-630 mRNA expression increased and TLR4 mRNA expression significantly decreased in the HG + miR-630 mimic group than in the HG + mimic NC group (P < 0.05). Furthermore, the levels of tumor necrosis factor-alpha (TNF-α), interleukin-1ß (IL-1ß), and IL-6 were significantly higher in the HG and HG + mimic NC groups than in NG group (P < 0.05). However, the levels of these cytokines were significantly lower in the HG + miR-630 mimic group than in the HG + mimic NC group (P < 0.05). Notably, changes in protein expression were observed. The HG and HG + mimic NC groups showed a significant decrease in E-cadherin protein expression, whereas TLR4, α-smooth muscle actin (SMA), and collagen IV protein expression increased (P < 0.05). Conversely, the HG + miR-630 mimic group exhibited a significant increase in E-cadherin protein expression and a notable decrease in TLR4, α-SMA, and collagen IV protein expression than in the HG + mimic NC group (P < 0.05). The miR-630 targets TLR4 gene expression. In vivo experiments demonstrated that DKD rats treated with miR-630 agomir exhibited significantly higher miR-630 mRNA expression than DKD rats injected with agomir NC. Additionally, rats treated with miR-630 agomir showed significant reductions in urinary albumin, blood glucose, TLR4, and proinflammatory markers (TNF-α, IL-1ß, and IL-6) expression levels (P < 0.05). Moreover, these rats exhibited fewer kidney lesions and reduced infiltration of inflammatory cells. CONCLUSION: MiR-630 may inhibit the inflammatory reaction of DKD by targeting TLR4, and has a protective effect on DKD.