title: Novel role of miR-181a in cartilage metabolism.
abstract: Micro RNA (miRNA) is a small non-coding post-transcriptional RNA regulator that is involved in a variety of biological events. In order to specify the role of miRNAs in cartilage metabolism, we comparatively analyzed the expression profile of known miRNAs in chicken sternum chondrocytes representing early and late differentiation stages. Interestingly, none of the miRNAs displaying strong expression levels showed remarkable changes along with differentiation, suggesting their roles in maintaining the homeostasis rather than cytodifferentiation of chondrocytes. Among these miRNAs, miR-181a, which is known to play critical roles in a number of tissues, was selected and was further characterized. Human microarray analysis revealed remarkably stronger expression of miR-181a in human HCS-2/8 cells, which strongly maintained a chondrocytic phenotype, than in HeLa cells, indicating its significant role in chondrocytes. Indeed, subsequent investigation indicated that miR-181a repressed the expression of two genes involved in cartilage development. One was CCN family member 1 (CCN1), which promotes chondrogenesis; and the other, the gene encoding the core protein of aggrecan, a major cartilaginous proteoglycan, aggrecan. Based on these findings, negative feedback system via miR-181a to conserve the integrity of the cartilaginous phenotype may be proposed.
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Kumi
authors.initials: K
authors.lastname: Sumiyoshi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kubota
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ohgawara
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kawata
authors.forename: Tarek
authors.initials: T
authors.lastname: Abd El Kader
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishida
authors.forename: Nao
authors.initials: N
authors.lastname: Ikeda
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shimo
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamashiro
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takigawa
mesh_terms: D015153:Blotting, Western; D002356:Cartilage / Q000378:metabolism*; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000378:metabolism; D055515:Cysteine-Rich Protein 61 / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D055515:Cysteine-Rich Protein 61; C540193:MIrn181 microRNA, human; D035683:MicroRNAs
keywords: CCN FAMILY; CCN1; CHONDROCYTE; GENE REGULATION; HOMEOSTASIS; miRNA