title: Expression of platelet-derived growth factor-C and insulin-like growth factor I in hepatic stellate cells is inhibited by miR-29.
abstract: MicroRNAs are short noncoding, endogenous RNA species that posttranscriptionally inhibit gene expression by targeting the untranslated region (UTR) of mRNAs. Recently, it was shown that miR-29 inhibits expression of extracellular matrix proteins such as collagens, suggesting an antifibrotic function of miR-29. In the present study, we now investigated the role of miR-29 in profibrogenic growth factor expression as a further central mechanism of fibrosis. Screening of databases revealed putative miR-29 target sequences in the mRNA of platelet-derived growth factor (PDGF)-B, PDGF-B receptor, PDGF-C, vascular endothelial growth factor-A, and insulin-like growth factor (IGF)-I. To analyze miR-29 interaction with the predicted binding sites, we cloned the 3'-UTR sequences of the putative targets in fusion to the luciferase-reporter coding sequence. Functional miR-29 binding to PDGF-C and IGF-I mRNA sequences, but not to the corresponding mutants, was then proven by reporter assays. Hepatic stellate cells (HSC) that transdifferentiate into myofibroblasts, producing extracellular matrix proteins and profibrogenic growth factors, for example, the members of the PDGF family, are crucial for liver fibrosis. Myofibroblastic transition of primary HSC resulted in the loss of miR-29, but in a significant increase of PDGF-C and IGF-I. Compensation of reduced miR-29 levels by miR-29 overexpression in myofibroblastic HSC was followed by a definitive repression of IGF-I and PDGF-C synthesis. After experimental fibrosis, induced by bile-duct occlusion, miR-29 expression was shown to be reduced, but IGF-I and PDGF-C expression was upregulated, correlating inversely to the miR-29 pattern. Thus, we conclude that miR-29, downregulated during fibrosis, acts as an antifibrogenic mediator not only by targeting collagen biosynthesis, but also by interfering with profibrogenic cell communication via PDGF-C and IGF-I.
authors.affiliation: Institute for Pathology, University Hospital of Cologne, Koeln, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Kwiecinski
authors.forename: Natalia
authors.initials: N
authors.lastname: Elfimova
authors.forename: Andrea
authors.initials: A
authors.lastname: Noetel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Töx
authors.forename: Hans-Michael
authors.initials: HM
authors.lastname: Steffen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hacker
authors.forename: Roswitha
authors.initials: R
authors.lastname: Nischt
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Dienes
authors.forename: Margarete
authors.initials: M
authors.lastname: Odenthal
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D002450:Cell Communication; D002454:Cell Differentiation; D002478:Cells, Cultured; D015870:Gene Expression; D055166:Hepatic Stellate Cells / Q000378:metabolism* / Q000473:pathology; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008106:Liver Cirrhosis, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D058628:Myofibroblasts / Q000378:metabolism / Q000473:pathology; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D008222:Lymphokines; C526366:MIRN29 microRNA, rat; D035683:MicroRNAs; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C411423:platelet-derived growth factor C; C467498:vascular endothelial growth factor A, rat; D007334:Insulin-Like Growth Factor I