Several studies have suggested that long intergenic noncoding RNAs are involved in the progression of diabetic nephropathy (DN). However, the exact role and regulatory mechanism of long noncoding RNA (lncRNA) NR_038323 in diabetic nephropathy (DN) remain largely unclear. In the present study, we found that lncRNA NR_038323 overexpression ameliorated the high glucose (HG)-induced expression levels of collagen I, collagen IV, and fibronectin, whereas lncRNA NR_038323 knockdown exerted the opposite effects. Moreover, the results of bioinformatic prediction, luciferase assay, and fluorescence in situ hybridization (FISH) demonstrated that lncRNA NR_038323 directly interacted with miR-324-3p. Additionally, miR-324-3p mimic aggravated the HG-induced expression levels of collagen I, collagen IV, and fibronectin by dual-specificity protein phosphatase-1 (DUSP1) expression to activate p38 mitogen-activated protein kinase (MAPK) and ERK1/2 pathways. In contrast, overexpression of DUSP1 attenuated the HG-induced expression levels of collagen I, collagen IV, and fibronectin via inactivation of p38 MAPK and ERK1/2 pathways. In addition, lncRNA NR_038323 knockdown increased the expression levels of collagen I, collagen IV, and fibronectin by upregulating DUSP1 expression during HG treatment, which were markedly reversed by miR-324-3p inhibitor. Furthermore, these molecular changes were verified in the human kidney samples of DN patients. Finally, overexpression of lncRNA NR_038323 ameliorated the interstitial fibrosis in STZ-induced diabetic nephrology (DN) rat via miR-324-3p/DUSP1/p38MAPK and ERK1/2 axis. In conclusion, our data indicate that overexpression of lncRNA NR_038323 may suppress HG-induced renal fibrosis via the miR-324-3p/DUSP1/p38MAPK and ERK1/2 axis, which provides new insights into the pathogenesis of DN.

Acute kidney injury (AKI) constitutes a significant public health issue. Sepsis accounts for over 50 % of AKI cases in the ICU. Recent findings from our research indicated that the PRD1-BF1-RIZ1 homeodomain protein 16 (PRDM16) inhibited the progression of diabetic kidney disease (DKD). However, its precise role and regulatory mechanism in sepsis-induced AKI remain obscure. This study reveals that lipopolysaccharide (LPS) and cecum ligation and puncture (CLP) instigated PRDM16 expression in Boston University mouse proximal tubule (BUMPT) cells and mouse kidneys, respectively. Functionally, PRDM16 curtailed LPS-induced ferroptosis. Mechanistically, PRDM16 associates with the promoter regions of nuclear factor-erythroid 2-related factor-2 (NRF2) and augments its expression, subsequently enhancing glutathione peroxidase 4 (GPX4) expression. Additionally, PRDM16 directly engages with the promoter regions of GPX4, stimulating its expression. Notably, these observations were corroborated in human renal tubular epithelial (HK-2) cells. Furthermore, the ablation of PRDM16 from kidney proximal tubules in mice inhibited NRF2 and GPX4 expression, leading to decreased glutathione (GSH)/oxidized glutathione (GSSG) ratio, increased Fe²⁺ and reactive oxygen species (ROS) production, exacerbated ferroptosis, and AKI progression. Conversely, PRDM16 knock-in exhibited the opposite effects. Ultimately, adenovirus (ADV)-PRDM16 plasmid or poly (lactide-glycolide acid) (PLGA)-encapsulated formononetin not only mitigated sepsis-induced AKI but also alleviated liver, cardiac, and lung injury. In summary, PRDM16 inhibits ferroptosis via the NRF2/GPX4 axis or GPX4 to prevent sepsis-induced multi-organ injury, including AKI. PLGA-encapsulated formononetin presents a promising therapeutic approach.

Recent studies have reported that upregulation of disulfide-bond A oxidoreductase-like protein (DsbA-L) prevented lipid-induced renal injury in diabetic nephropathy (DN). However, the role and regulation of proximal tubular DsbA-L for renal tubulointerstitial fibrosis (TIF) remains unclear. In current study, we found that a proximal tubules-specific DsbA-L knockout mouse (PT-DsbA-L-KO) attenuated UUO-induced TIF, renal cell apoptosis and inflammation. Mechanistically, the DsbA-L interacted with Hsp90 in mitochondria of BUMPT cells which activated the signaling of Smad3 and p53 to produce connective tissue growth factor (CTGF) and then resulted in accumulation of ECM of BUMPT cells and mouse kidney fibroblasts. In addition, the progression of TIF caused by UUO, ischemic/reperfusion (I/R), aristolochic acid, and repeated acute low-dose cisplatin was also alleviated in PT-DsbA-L-KO mice via the activation of Hsp90 /Smad3 and p53/CTGF axis. Finally, the above molecular changes were verified in the kidney biopsies from patients with obstructive nephropathy (Ob). Together, these results suggest that DsbA-L in proximal tubular cells promotes TIF via activation of the Hsp90 /Smad3 and p53/CTGF axis.

The prediction of mortality for septic acute kidney injury (AKI) has been assessed by a number of potential biomarkers, including long noncoding RNAs (lncRNAs). However, the validation of lncRNAs as biomarkers, particularly for the early stages of septic AKI, is still warranted. Our results indicate that the lncRNA TCONS_00016233 is upregulated in plasma of sepsis-associated non-AKI and AKI patients, but a higher cutoff threshold (9.5 × 105, copy number) provided a sensitivity of 71.9% and specificity of 89.6% for the detection of AKI. The plasma TCONS_00016233 was highly correlated with serum creatinine, tissue inhibitor metalloproteinase-2 (TIMP-2), insulin-like growth factor binding protein-7 (IGFBP7), interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), C-reactive protein (CRP), and urinary TCONS_00016233. Lipopolysaccharide (LPS) induced the expression of lncRNA TCONS_00016233 via the Toll-like receptor 4 (TLR4)/p38 mitogen-activated protein kinase (MAPK) signal pathway in human renal tubular epithelial (HK-2) cells. Furthermore, TCONS_00016233 mediates the LPS-induced HK-2 cell apoptosis and the expression of IL-1β and TNF-α. Mechanistically, TCONS_00016233 acts as a competing endogenous RNA (ceRNA) to prevent microRNA (miR)-22-3p-mediated downregulation of the apoptosis-inducing factor mitochondrion-associated 1 (AIFM1). Finally, overexpression of TCONS_00016233 is capable of aggravating the LPS- and cecal ligation and puncture (CLP)-induced septic AKI by targeting the miR-22-3p/AIFM1 axis. Taken together, our data indicate that TCONS_00016233 may serve as an early diagnosis marker for the septic AKI, possibly acting as a novel therapeutic target for septic AKI.

Despite DNA methylation occurred in acute kidney injury (AKI), how it influenced progression of AKI remains unclear. Methyl-CpG-binding domain protein 2 (MBD2), a protein readers of methylation, was used to analyze the impact of DNA methylation on vancomycin (VAN)-induced AKI. Here, in cultured human kidney tubular epithelial cells (HK-2), we show that knockdown of MBD2 by siRNA attenuated VAN-induced apoptosis, caspase activity, and the expression of BAX and cleaved caspase 3. Interestingly, knockdown of MBD2 by siRNA was associated with the suppression of miR-301a-5p. Mechanistic studies confirmed MBD2 binds to these methylated CpG elements of miR-301a-5p promoter, and then activates miR-301a-5p promoter by suppressing methylation. Furthermore, anti-miR-301a-5p significantly blocked VAN-induced apoptosis and caspase activity in HK-2 cells, which was accompanied by downregulation of p53, and upregulation of MITF, HDGF and MDM-4 together. The latter genes were further identified as target genes of miR-301a-5p, and silencing of MDM-4 promoted p53 accumulation. In vivo, mice with MBD2 knockout (MBD2-KO) were counteracted to VAN-induced AKI, indicated by the analysis of renal function, histology, apoptosis and inflammation. MBD2-KO also significantly suppressed the expression of miR-301a-5p, p53, BAX and cleaved caspase 3, and restored the expression of MDM-4, MITF and HDGF. Finally, in vivo inhibition of miR-301a-5p also ameliorated VAN-induced AKI. Together, these results show the novel MBD2/miR-301a-5p/MITF, HDGF and MDM-4/p53 pathway in VAN-induced AKI.

Recent studies have demonstrated that paclitaxel might inhibit renal fibrosis. However, the underlying molecular mechanism remains unclear. In this study, we hypothesized that low-dose paclitaxel may block the STAT3 (signal transducer and activator of transcription 3) signaling to attenuate fibrosis in a mouse model with unilateral ureteral obstruction. Both NRK-49F cells and mice with unilateral ureteral obstruction were treated with paclitaxel. The results showed that paclitaxel treatment resulted in a dose- and time-dependent decrease in tyrosine-phosphorylated STAT3, and inhibited the expression of fibronectin, alpha-smooth muscle actin (α-SMA), and collagen I in cultured NRK-49F cells. S3I-201, an STAT3 inhibitor, also suppressed the expression of fibronectin, α-SMA, and collagen I in cultured NRK-49F cells. Mechanistically, paclitaxel treatment blocked the STAT3 activity by disrupting the association of STAT3 with tubulin and inhibiting STAT3 nucleus translocation. Furthermore, paclitaxel also ameliorated renal fibrosis by down-regulating the expression of fibronectin, α-SMA, and collagen I, and suppressed the infiltration of macrophages and production of TNF-α, IL-1β, TGF-β, and ICAM-1 (intercellular adhesion molecule 1) by inhibition of STAT3 activity in obstructive nephropathy. These results suggest that paclitaxel may block the STAT3 activity by disrupting the association of STAT3 with tubulin and inhibiting STAT3 nucleus translocation, consequently leading to the suppression of renal interstitial fibroblast activation and the development of renal fibrosis, and inhibition of proinflammatory cytokine production.