#3467 INHIBITION OF ACYL-COA SYNTHETASE MEDIUM CHAIN FAMILY MEMBER 3 PROMOTES RENAL FIBROSIS BY ACCELERATING CELLULAR SENESCENCE IN TUBULAR EPITHELIAL CELLS

Abstract

Abstract Background and Aims Cellular senescence is associated with renal disease progression. Accelerated tubular cell senescence promotes the pathogenesis of renal fibrosis no matter caused by natural aging or disease. However, the underlying mechanism is unknown. Method Proteomic analysis of natural aging kidney from 20-week mice was used to find potential target protein which is acyl-CoA synthetase medium chain family member 3 (Acsm3). After finding it, two Acsm3 inhibitor (4-Methylsalicylic acid and 2-hydroxyoctanoic acid) were used separately to treat natural aging and pathological aging (unilateral ureteral obstruction induced renal fibrosis) mice. Renal histological injury was measured by HE and Masson's trichrome staining. SA-β-gal staining was used to check cellular senescence. Renal tissues of the mice were analysed by western blot and qPCR assay for the expression of Acsm3, fibrosis and cellular senescence related proteins and genes. In order to avoid drug toxicity, tubular epithelial cells were treated with Acsm3 SiRNA to explore the effects of Acsm3 in vitro. Results Firstly, we confirmed that cellular senescence happened in both elderly mice and UUO mice and found SA-β-gal positive cells were mainly tubular epithelial cells. After analysing proteomic sequencing data, Acsm3 is the protein which increased dramatically as the top one protein in elderly mice. We also found Acsm3 increased in tubular cells specifically in adult mice compared with fetal mice from KIT single cell database, which suggested that Acsm3 might have effects for kidney development. After validating changes and location of Acsm3, we treated natural aging and UUO mice with two Acsm3 inhibitor to check the function of Acsm3, separately. Administration of Acsm3 inhibitor (no matter 4-Methylsalicylic acid or 2-hydroxyoctanoic acid) could induce renal histological injuries, renal fibrosis, with significantly increased COL6, α-SMA and FN expression in both natural aging and UUO induced renal fibrosis. The cellular senescence was also observed to increase after Acsm3 inhibitor treatment with growth P21 and P16 expression. In addition, pro-inflammatory senescence-associated secretory phenotype (SASP) including IL6 and MCP1 increased as well. In order to avoid kidney injury induced by drug toxicity instead of by inhibition of Acsm3, we transfected Acsm3 SiRNA in tubular epithelial cells to check in vitro. Similarly, the inhibition of Acsm3 augmented cellular senescence and SASP of tubular epithelial cells as what we found in vivo. It supported that inhibition of Acsm3 could induce senescence of tubular epithelial cells and thus to promote kidney fibrosis. Conclusion These findings suggested that Acsm3 could be an important protector for renal fibrosis by inhibiting cellular senescence of tubular epithelial cells. The underlying mechanism needs to explore more.