Background Nephrotic syndrome (NS) is a chronic kidney disease mainly caused by impaired podocytes, ultimately resulting in massive proteinuria or even end-stage renal disease (ESRD). Methods The objective of this study was to explore the potential pathogenesis of NS caused by podocyte injury, and further explore the underlying mechanism through data mining , bioinformatics analysis, and experimental verification. The integrated analyses including Seurat, CellChat, gene ontology (GO), and molecular docking were performed based on the single-cell RNA-seq data (scRNA-seq). The adriamycin (ADR)-induced podocyte injury model in vitro was established to conduct the experimental verification for bioinformatics analysis results through western blot and real-time quantitative PCR (RT-qPCR). Results The results of bioinformatics analysis revealed that the bone morphogenetic protein (BMP) signaling pathway was involved in the podocyte-to-podocyte communication, which plays a crucial role in podocyte injury. The expression of BMP7 was significantly increased in ADR-induced podocytes through activating the Adenosine-monophosphate activated-protein kinase/Mammalian target of rapamycin (AMPK/mTOR) mediated autophagy pathway, and these findings were confirmed by in vitro experiments. Conclusion This study first demonstrated that BMP7 participated in ADR-induced podocyte injury. The BMP7/AMPK/mTOR mediated autophagy pathway may play a crucial role in podocyte injury, which may be the potential therapeutic target for NS patients.
Jun Li,Ji-Zhi Xu,Bo Dou,Teng-Fei Huang,Jie Chen,Tuan-Mei Wang,Hong-Juan Ouyang
The epithelial–mesenchymal transition (EMT) is closely associated with Crohn's disease (CD) related intestinal fibrosis, a condition whose prevalence is increasing annually among children. Recently, the CD marker gene microarray screening revealed an upregulation of circ_0001666 in the colon tissues of CD patients, but its underlying mechanisms remain unclear. In this study, we explored the molecular mechanism of circ_0001666 in regulating EMT-mediated fibrosis in CD in vitro. The levels of circ_0001666 and EMT-associated proteins were assessed in CD clinical samples, and a CD cell model was established using TGF-β1 to induce human intestinal epithelial cells (HIECs). Additionally, the expression levels of genes and proteins related to EMT and fibrosis were analyzed by quantitative real-time PCR and western blot, cell migration, and invasion were assessed via wound healing assay and transwell, respectively, and RNA pull-down and RNA immunoprecipitation assays were performed to verify the relationship between SRSF1 and BMP7 or circ_0001666. Circ_0001666 was overexpressed in the intestinal mucosal tissues of CD patients and was positively correlated with EMT. Silencing circ_0001666 inhibited the migration, invasion, EMT, and fibrosis of HIECs induced by TGF-β1. Mechanistically, circ_0001666 regulated BMP7 expression by interacting with SRSF1. Furthermore, the effects of inhibiting circ_0001666 on HIECs could be partially reversed by overexpressing SRSF1 or silencing BMP7. Collectively, circ_0001666 regulates TGF-β1-induced HIEC migration, invasion, EMT, and fibrosis. Circ_0001666 also promoted EMT-mediated fibrosis by interacting with SRSF1 to accelerate BMP7 mRNA decay. These findings provide new insights into the pathogenesis of CD and suggest that circ_0001666 might be a potential therapeutic target for CD.
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