MiR-26a modulates extracellular matrix homeostasis in cartilage

• Published in: Matrix biology 2015-04, Vol.43, p.27-34
• Main Authors: Etich, Julia, Holzer, Tatjana, Pitzler, Lena, Bluhm, Björn, Brachvogel, Bent
• Format: Article
• Language: English
• Subjects: 3' Untranslated Regions; Animals; Antigens, CD - genetics; Antigens, CD - metabolism; Cartilage; Cartilage Diseases - genetics; Cartilage Diseases - pathology; CD200; Cells, Cultured; Chondrocytes - metabolism; Chondrocytes - pathology; Collagen; Collagen Type IX - genetics; Collagen Type IX - metabolism; Collagen Type X - genetics; Collagen Type X - metabolism; Computational Biology - methods; Connective Tissue Growth Factor - genetics; Connective Tissue Growth Factor - metabolism; Extracellular matrix; Extracellular Matrix - genetics; Extracellular Matrix - metabolism; Growth plate; Hypertrophy - genetics; Mice; MicroRNAs - genetics; MicroRNAs - metabolism; MiR-26a
• ISSN: 0945-053X; 1569-1802
• DOI: 10.1016/j.matbio.2015.02.014

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. •MiR-26a and miR-26b are expressed in cartilage.•MiR-26a is upregulated in the hypertrophic growth plate.•MiR-26a inhibits colIagen IX and collagen X expression in growth plate chondrocytes.•MiR-26a can be used to modulate ECM deposition in cartilage.•MiR-26a can target CD200 expression.