LncRNA Gm17586 Reduces HSCs Activation by Increasing SIRT1 Transcript Activity to Enhance Smad3 Deacetylation

Long noncoding RNAs (lncRNAs) play crucial roles in liver fibrosis (LF). We previously showed that the key lncRNA Gm17586 is involved in LF, but its molecular mechanism remains unclear. Primary hepatic stellate cells (HSCs) were isolated from LF mice. Real-time quantitative PCR and Western blotting were used to detect the expression of lncRNA Gm17586, Sirtuin 1 (SIRT1), and Smad homolog 3 (Smad3). Cell counting kit-8 and flow cytometry were used to detect the cell viability and cell cycle of the HSCs. Finally, immunofluorescence (IF) and fluorescence in situ hybridization (FISH) were used to observe the cellular colocalization of lncRNA Gm17586 and SIRT1. In HSCs from LF mice, the expression of the lncRNA Gm17586 was significantly reduced and negatively correlated with the expression of the HSCs activation markers α-smooth muscle actin (α-SMA) and collagen I. Overexpression of the lncRNA Gm17586 suppressed α-SMA and collagen I expression, as well as HSCs proliferation. Bioinformatics analysis and FISH experiments revealed that the lncRNA Gm17586 has potential binding sites on SIRT1 mRNA and shares a common subcellular localization. Notably, overexpression of the lncRNA Gm17586 led to marked increases in SIRT1 mRNA and protein levels. Further studies on the role of SIRT1 as a deacetylase revealed that overexpression of SIRT1 significantly reduced Smad3 mRNA and protein levels. Importantly, SIRT1 overexpression also markedly decreased Smad3 protein acetylation, suggesting that a mechanism exists by which Smad3 is regulated via deacetylation in HSCs. The results of this study suggested that downregulation of lncRNA Gm17586 expression reduced the expression of SIRT1, leading to decreased Smad3 deacetylation and promoting HSCs activation. The lncRNA Gm17586 may be a novel therapeutic target for the diagnosis and treatment of LF.