Dysregulation of argininosuccinate synthase 1, phosphoenolpyruvate carboxykinase 1, and carbonyl reductase 3: Key arginine-proline metabolic mediators in mesangioproliferative glomerulopathies.

Abstract

Aberrant proliferation of mesangial cells (MCs) is a central driver of glomerular injury in IgA nephropathy (IgAN) and lupus nephritis (LN), the two most common mesangioproliferative glomerulopathies. Emerging evidence implicates dysregulated arginine-proline metabolism in this process; however, the key regulatory genes and underlying mechanisms remain incompletely defined. Here, we performed integrative bulk RNA sequencing of glomerular datasets and applied machine learning algorithms (LASSO and SVM-RFE) to identify disease-specific differentially expressed genes (DEGs) linked to the arginine-proline metabolic pathway. We identified 34 LN-specific and 18 IgAN-specific DEGs, among which ASS1, PCK1, and CBR3 emerged as core hub genes through feature selection and network analyses. A nomogram-based diagnostic model incorporating these genes demonstrated strong predictive performance, with AUC values exceeding 0.75 in internal cohorts and robust validation across external datasets. Single-cell RNA sequencing of mouse models delineated seven MC subclusters, highlighting Rasl12and Col3a1subpopulations with pronounced proliferative-inflammatory phenotypes, characterized by downregulated ASS1 and PCK1 and upregulated CBR3. These transcriptional patterns were corroborated in vivo in anti-Thy1 nephritis rats, BAFF-transgenic IgAN mice, and MRL/lpr LN mice, where altered gene expression correlated with mesangial hyperplasia, macrophage infiltration, and elevated inflammatory cytokines. Functional assays in PDGF-BB-stimulated human MCs further demonstrated that overexpression of ASS1 or PCK1, or knockdown of CBR3, attenuated MC activation, proliferation, and proinflammatory crosstalk with macrophages. Collectively, our results position ASS1, PCK1, and CBR3 as pivotal regulators of arginine-proline metabolism in mesangial proliferation, establishing them as innovative diagnostic biomarkers and therapeutic targets for precise management of IgAN and LN.