title: Liver fibrosis causes downregulation of miRNA-150 and miRNA-194 in hepatic stellate cells, and their overexpression causes decreased stellate cell activation.
abstract: Activation of hepatic stellate cells (HSC) results in their proliferation and in the secretion of extracellular matrix (ECM) proteins, which leads to hepatic fibrosis. microRNAs (miRNAs) have been shown to regulate various cell functions, such as proliferation, differentiation, and apoptosis. Hence, we have analyzed the miRNAs that were differentially expressed in HSC isolated from sham-operated and bile duct-ligated rats. Expression of two miRNAs, miRNA-150 and miRNA-194, was reduced in HSC isolated from fibrotic rats compared with sham-operated animals. These two miRNAs were overexpressed in LX-2 cells, and their ability to inhibit cell proliferation, the expression of smooth muscle alpha-actin (SMA), a marker for activation, and collagen type I, a marker for ECM secretion, was determined. Overexpression of these two miRNAs resulted in a significant inhibition of proliferation (P < 0.05) and reduced SMA and collagen I levels compared with either untreated cells or nonspecific miRNA-expressing cells. Next, the protein targets of these two miRNAs were found using bioinformatics approaches. C-myb was found to be a target for miRNA-150, and rac 1 was found to be one of the targets for miRNA-194. Therefore, we studied the expression of these two proteins by overexpressing these two miRNAs in LX-2 cells and found that overexpression of miRNA-150 and miRNA-194 resulted in a significant inhibition of c-myb and rac 1 expression, respectively. We conclude that both miRNA-150 and miRNA-194 inhibit HSC activation and ECM production, at least in part, via inhibition of c-myb and rac 1 expression.
authors.affiliation: Dept. of Internal Medicine, Transplant Research Program, 4635 2nd Ave., Research Bldg. I, Rm. 1001, UCDavis Medical Ctr., Sacramento, CA 95817, USA. skvenugopal@ucdavis.edu
authors.forename: Senthil K
authors.initials: SK
authors.lastname: Venugopal
authors.forename: Joy
authors.initials: J
authors.lastname: Jiang
authors.forename: Tae-Hun
authors.initials: TH
authors.lastname: Kim
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Si-Si
authors.initials: SS
authors.lastname: Wang
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Torok
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Zern
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D030541:Databases, Genetic; D015536:Down-Regulation / Q000235:genetics; D005109:Extracellular Matrix / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D020570:Genes, myb / Q000235:genetics; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000502:physiology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D008103:Liver Cirrhosis / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein
chemical_list: D000199:Actins; D024042:Collagen Type I; C551974:MIRN150 microRNA, rat; C551975:MIRN194 microRNA, rat; D035683:MicroRNAs; D009479:Neuropeptides; C484602:Rac1 protein, mouse; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein