Linc-SCRG1 Accelerates Liver Fibrosis By Down-regulating TTP Protein

Objective:Long non-coding RNA represent a group of transcripts that are >200 nt in length but without protein coding potential.Recent studies showed that lnc RNA plays an important role in regulating diverse diseases.However,the researches regarding Inc RNA in liver fibrosis are still limited.The aim of our study is to find liver fibrosis-specific expressing Inc RNA and explore their underlying functions and mechanisms in liver fibrosis.Methods:To explore liver fibrosis–related lnc RNAs,Agilent genechips were performed in humam fibrosis liver tissues.Linc-SCRG1 was selected for further study,q PCR and northern blot were performed on the clinical specimens.LX2 was stimulated by TGF-?1,the expression of linc-SCRG1 Bcl2,?-SMA and Col I was detected by q PCR.To determine how linc-SCRG1 regulating liver fibrosis,we predicted its target proteins using RBPDB software,which was confirmed by RNA pull-down assays and RIP assays.MTT assay detection of proliferation,Transwell assay detection of invasion,flow cytometric and TUNEL assay detection of apoptosis,flow cytometric detection of cell cycle and IF detection of activation were conducted in LX2 cells knockdown of linc-SCRG1(si-linc SCRG1),overexpression TTP(OV-TTP)or knockdown of linc-SCRG1 and TTP(si-linc SCRG1+si-TTP).Results:Through microarray analysis,there were 1455 up-regulated lnc RNAs in human cirrhotic tissues and linc-SCRG1(located in chr4:173453013-173520960;transcript length 3118bp)was up-regulated 13.62-fold.Northern blot and q PCR verified that linc-SCRG1 significantly increased in cirrhotic liver tissues compared with nonfibrotic tissues.Linc-SCRG1 was up-regulated in activated LX2 cells induced by TGF-?1,whereas the m RNA expression of Bcl2,a-SMA and Col I were also up-regulated(p<0.01).TTP was predicted as the target proteins of linc-SCRG1,RNA pull-down and RIP assays showed linc-SCRG1 could specifically bind and decrease TTP proteins.Knock-down of linc-SCRG1 significantly reversed the effects of TGF-?1 on LX2,including inhibiting activation,promoting apoptosis,reducing proliferation and lessening invasion.Overexpressing TTP resulted in knock down of linc SCRG1 and degraded downstream target genes(MMP-2 and TNF-a)in activated LX2.Overexpressing TTP had the same effects as si-linc SCRG1,whereas knock-down of TTP had reversal effects on si-linc SCRG1 in activated LX2.Conclusion:Linc-SCRG1 reduced TTP and restricted its degradation of target genes TNF-? and MMP-2.Therefore,linc-SCRG1 had a repressing TTP-elicited inactivation effect on HSCs phenotypes.Inhibition of linc-SCRG1 may be a novel therapeutic approach to inactivate HSCs and extenuate human liver fibrosis.