LncRNA evf-2 Exacerbates Podocyte Injury in Diabetic Nephropathy by Inducing Cell-Cycle Reentry and Inflammation through Distinct Mechanisms Triggered by Heterogeneous Nuclear Ribonucleoprotein U (hnRNPU)

Background: Albuminuria is a hallmark of diabetic nephropathy (DN), heralding the onset of progressive renal dysfunction. Podocyte injury stands as a primary contributor to proteinuria in DN. Our previous study revealed a significant upregulation of lncRNA EVF-2 in podocytes of DN patients, correlating with cell cycle re-entry and inflammation. Notably, the potential contribution of evf-2 to the pathogenesis and progression of kidney diseases, particularly DN, remains largely unexplored. Methods: We used specific knockout or knockdown of lncRNA evf-2 in diabetic mice or cultured podocytes to confirm the effects of evf-2 in DN. RNA sequencing of evf-2-overexpressing podocytes was used to find out the molecular pathways. Chromatin Isolation by RNA purification-mass spectrometry (ChIRP-MS) was performed to find out the binding proteins of evf-2. Results: Specific knockout or knockdown of lncRNA evf-2 in diabetic mice or cultured podocytes alleviated podocyte injury driven by cell cycle re-entry and inflammation. RNA sequencing of evf-2-overexpressing podocytes unveiled a predominant enrichment of upregulated mRNAs in cell cycle and inflammation pathways, with alternative splicing events occurring in cell cycle-related mRNAs Ccnb1 and Tacc3 but not in upregulated inflammatory factors. Chromatin isolation by RNA purification- mass spectrometry (ChIRP-MS) analysis highlighted the involvement of ribonucleoprotein complex and mRNA processing-related proteins, with hnRNPU emerging as the primary binding partner of evf-2 in spliceosomes. Partial restoration of the upregulation of the cell cycle and inflammation-related mRNA expression induced by evf-2 overexpression occurred upon hnRNPU-specific knockdown, accompanied by changes in splice variants of Ccnb1 and Tacc3 mRNAs (Ccnb1-202/201 and Tacc3-207/206). Conclusion: Our study elucidates the interaction between lncRNA evf-2 and hnRNPU, culminating in the upregulation of cell cycle-related genes and inflammatory factors through diverse pathways, potentially involving transcriptional activation, RNA stability modulation, alternative splicing or translational regulation. These findings introduce a novel molecular target and signaling pathway for the treatment of DN. Funding: Government Support – Non-U.S.