title: MiR-26a modulates extracellular matrix homeostasis in cartilage.
abstract: MicroRNAs (miRNAs) may represent new therapeutic targets for bone and joint diseases. We hypothesized that several cartilage-specific proteins are targeted by a single miRNA and used bioinformatics to identify a miRNA that can modulate extracellular matrix (ECM) homeostasis in cartilage. Bioinformatic analysis of miRNA binding sequences in the 3'-untranslated region (3'-UTR) of target genes was performed to identify a miRNA that could bind to the 3'-UTR of cartilage matrix-related genes. MiRNA expression was studied by quantitative PCR of microdissected growth plate cartilage and binding to the 3'-UTR sequences was analyzed by luciferase interaction studies. Levels of proteins encoded by target genes in cultures of miR-26a mimic- or inhibitor-transfected chondrocytes were determined by FACS or immunoblot analysis. The complementary binding sequence of miR-26a and miR-26b was found in the 3'-UTR of the prehypertrophic/hypertrophic-specific genes Cd200, Col10a1 as well as Col9a1 and Ctgf. Both miRNAs were expressed in cartilage and only miR-26a was downregulated in hypertrophic growth plate cartilage. MiR-26a could interact with the 3'-UTR of Cd200 and Col10a1 in luciferase binding studies, but not with Col9a1 and Ctgf. However, protein expression of target genes and the ECM adaptor genes matrilin-3 and COMP was significantly altered in miR-26a mimic- or inhibitor-transfected chondrocytes, whereas the abundance of the cell surface receptor for insulin was not changed. In conclusion, miR-26a suppresses hypertrophic and ECM adaptor protein production. Dysregulation of miR-26a expression could contribute to ECM changes in cartilage diseases and this miRNA may therefore act as a therapeutic target.
authors.affiliation: Experimental Neonatology, Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Etich
authors.affiliation: Experimental Neonatology, Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Holzer
authors.affiliation: Experimental Neonatology, Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Pitzler
authors.affiliation: Experimental Neonatology, Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Bluhm
authors.affiliation: Experimental Neonatology, Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany. Electronic address: bent.brachvogel@uni-koeln.de.
authors.forename: Bent
authors.initials: B
authors.lastname: Brachvogel
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D002357:Cartilage Diseases / Q000235:genetics* / Q000473:pathology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism* / Q000473:pathology; D024081:Collagen Type IX / Q000235:genetics / Q000378:metabolism; D024121:Collagen Type X / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology / Q000379:methods; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism*; D006984:Hypertrophy / Q000235:genetics; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D015703:Antigens, CD; C526318:CCN2 protein, mouse; C570620:Col10a1 protein, mouse; D024081:Collagen Type IX; D024121:Collagen Type X; D035683:MicroRNAs; C543693:Mirn26 microRNA, mouse; D055513:Connective Tissue Growth Factor; C042739:antigens, CD200
keywords: CD200; Cartilage; Collagen; Extracellular matrix; Growth plate; MiR-26a