LncRNA P4HA2-AS1 Drives Renal Interstitial Fibrosis via TRIM32-Mediated K63 Ubiquitination of ULK1 and Autophagic Dysregulation

Renal interstitial fibrosis (RIF), the central pathological driver of chronic kidney disease (CKD) progression, remains mechanistically incompletely defined. While long non-coding RNAs (lncRNAs) are emerging as critical regulators of CKD, their roles in RIF pathogenesis are poorly understood. Here, we identify the fibrosis-associated lncRNA P4HA2-AS1 as a key modulator of RIF through integrated analyses of unilateral ureteral obstruction (UUO) mice and TGF-ß-stimulated human renal tubular epithelial cells (HK-2), combined with RNA sequencing, RNA pull-down, ubiquitination profiling, and autophagic flux assays. P4HA2-AS1 was markedly upregulated in fibrotic kidneys, and its suppression attenuated fibrotic phenotypes in vivo and in vitro while restoring autophagic flux. Mechanistically, P4HA2-AS1 directly binds the E3 ubiquitin ligase TRIM32, impeding its proteasomal degradation. This stabilization enhances TRIM32-mediated K63-linked ubiquitination of ULK1, a master autophagy initiator, leading to aberrant autophagic activation and fibrotic progression. Our study uncovers a previously unrecognized P4HA2-AS1/TRIM32/ULK1 axis that couples dysregulated autophagy to RIF, proposing lncRNA-protein interaction targeting as a therapeutic strategy against renal fibrosis. Overall design: RNA-seq profiling of TGF-ß (10ng/ml for 24h) treated or untreated HK-2 cells and their knockdown derivative (shP4HA2-AS1).