Dataset Information

Repairing of isoaspartyl residues by PCMT1 alleviates renal fibrosis through the repression of TGF-β1/TGFBR2/Smad signaling pathway

ABSTRACT: Protein L-isoaspartyl/D-aspartyl Methyltransferase (PCMT1) plays a pivotal role in repairing a spontaneous post-translational modification (PTM) of L-isoaspartyl residues resulted from asparagine deamidation or aspartate isomerization. This PTM is particularly important for extracellular matrix (ECM) proteins because their low turnover rate and are susceptible to factors that could accelerate such modification. Therefore, it becomes imperative to comprehensively investigate the impact of PCMT1 on ECM homeostasis and its associated pathological alterations. In this study, we revealed that secreted PCMT1 repairs the isoaspartyl residues of the TGFBR2 protein on the cell membrane to suppress TGF-β1/Smad pathway. Through this novel PTM regulation, PCMT1 played essential roles in combating renal fibrosis, as lack of PCMT1 worsened tubular injury, collagen deposition, myofibroblast activation, and macrophage infiltration in total kidney and tubular contexts in a mouse model of chronic kidney disease. Moreover, PCMT1 level decreased in fibrotic kidney tissues and inversely related to kidney function in mice and in humans. Our study highlights the important function of PCMT1 in modifying proteins in the extracellular space and identified a novel role of PCMT1 in regulating TGF-β1 pathway in renal fibrosis. This study holds the potential of innovative therapeutic avenue for the mitigation of renal fibrosis.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE248435 | GEO | 2024/01/01

REPOSITORIES: GEO

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Project description:We aimed to identify miRNA biomarkers of renal injury in kidney biopsies from patients with lupus nephritis. MiRNA profiles of 8 patients were analyzed for correlation with various clinical features including Progression, Activity, Chronicity, and Time to Kidney Failure. MicroRNAs (miRs) are promising biomarkers and are involved in pathogenesis of kidney diseases. We aimed to identify miR biomarkers of renal injury in kidney biopsies from patients with lupus nephritis and study their potential role in renal fibrosis. miR-150 was significantly increased in kidneys with high chronicity compared to low chronicity and it correlated positively with chronicity index scores and renal collagen I expression. In kidneys with high chronicity, miR-150 was found predominantly in proximal tubular cells (PTCs) and was moderately expressed in podocytes and to lesser degree in mesangial cells (MCs). We hypothesized that miR-150 increases fibrosis by downregulating a negative regulator of profibrotic proteins. Suppressor of cytokine signaling1 (SOCS1) is a predicted target of miR-150 and has shown antifibrotic role. After confirming that SOCS1 is a direct target of miR-150, we showed that transfection of a miR-150 analog downregulated SOCS1 protein and upregulated the profibrotic proteins fibronectin, collagen I, collagen III, and TGF-β1 in both primary normal human renal PTCs and MCs. A similar effect was seen when using a SOCS1 siRNA to confirm that the effect of miR-150 on profibrotic proteins is mediated through SOCS1. Stimulation with TGF-β1 induced miR-150 increase in PTCs and human podocytes but not MCs. These results suggest that miR-150 might be a useful quantitative renal biomarker of kidney injury in lupus nephritis and that miR-150, which might be partially induced by TGF-β1, plays an important role in renal fibrosis by increasing profibrotic molecules through downregulation of SOCS1. FFPE kidney specimens (n=25) including baseline and repeated needle renal biopsies were from 14 patients with LN enrolled in IRB-approved protocols at the NIDDK between 1976 and 1999. The specimens were divided in two groups based on histological chronicity index (CI). CI ≥ 4 were categorized as having high degree of chronicity of chronic kidney injury. 18 kidneys from 8 patients including high CI (n=9) and low CI (n=9) were used for miR profiling by Affymetrix microRNA microarrays.

Dataset Information

Repairing of isoaspartyl residues by PCMT1 alleviates renal fibrosis through the repression of TGF-β1/TGFBR2/Smad signaling pathway

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