linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin

The biologic roles of long noncoding RNAs (lncRNAs) in liver fibrosis remained unknown. Through microarray analysis, linc-SCRG1 (a lncRNA with transcript length 3118 bp) was found up-regulated 13.62-fold in human cirrhotic tissues. Quantitative PCR verified that linc-SCRG1 increased along with liver fibrosis progression in human tissues and in activated LX2 cells induced by TGF-β1. Knockdown of linc-SCRG1 significantly reversed the effects of TGF-β1 on LX2, including inhibiting activation, promoting apoptosis, reducing proliferation, lessening invasion, and down-regulating genes [fibrosis-related mRNA: α-smooth muscle actin ( α-SMA), type I collagen, and B-cell lymphoma-2; invasion-related mRNA: matrix metallopeptidase-2 ( MMP-2), MMP-9, and MMP-13; inflammation-related mRNA: TNF-α, IL-6, and IL-10]. linc-SCRG1 had binding sites with tristetraprolin (TTP), a kind of RNA-binding protein, and specifically combined to TTP proteins. Overexpression of linc-SCRG1 would cause TTP mRNA unstably and proteins decreasing. TTP mRNA was proved having negative relevance with linc-SCRG1 and was gradually reduced during human liver fibrosis progression. Overexpressing TTP resulted in knockdown of lincSCRG1 and degraded downstream target genes ( MMP-2 and TNF-α) in activated LX2. Overexpressing TTP had the same effects as small interfering RNA-lincSCRG1 (si- lincSCRG1), whereas knockdown of TTP had reversal effects on si- lincSCRG1 in activated LX2. In summary, linc-SCRG1 reduced TTP and restricted its degradation of target genes TNF-α and MMP-2. Therefore, linc-SCRG1 had a repressing TTP-elicited inactivation effect on hepatic stellate cell (HSC) phenotypes. Inhibition of linc-SCRG1 may be a novel therapeutic approach to inactivate HSCs and extenuate human liver fibrosis.-Wu, J.-C., Luo, S.-Z., Liu, T., Lu, L.-G., Xu, M.-Y. linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin.