title: Nuclear factor E2 p45-related factor 2 negatively regulates chondrogenesis.
abstract: The transcription factor nuclear factor E2 p45-related factor 2 (Nrf2) forms heterodimers with small musculoaponeurotic fibrosarcoma (Maf) proteins for the selective recognition of the antioxidant responsive element on target genes, followed by the regulation of gene expression of phase II detoxifying enzymes as well as oxidative-stress-inducible proteins in different tissues. In the present study, we investigated the role of Nrf2 in the regulation of chondrocyte differentiation as well as the expression pattern of Nrf2 in cartilage. In tibia from embryonic mice at E15.5, Nrf2 mRNA expression was restricted to both proliferating and pre-hypertrophic chondrocytes, with few signals in early and late hypertrophic chondrocytes expressing both type X collagen and osteopontin. On in situ hybridization analysis of tibia from neonatal mice at 1 day after birth, by contrast, Nrf2 was expressed in all chondrocytic layers in addition to osteoblasts attached to cancellous bone. In pre-chondrogenic cell line ATDC5 cells, furthermore, expression of Nrf2 mRNA was also confirmed together with mRNA expression of the Kelch-like ECH associating protein 1 and small Maf proteins. In ATDC5 cells stably transfected with Nrf2, significant inhibition was seen in the differentiation-dependent induction of alkaline phosphatase and increase in the Alcian blue staining intensity. Furthermore, stable overexpression of Nrf2 significantly decreased mRNA expression of several chondrocyte differentiation markers such as type II collagen, type X collagen and osteopontin. These data suggest that Nrf2 may be a negative regulator of the cellular differentiation toward maturation in chondrocytes.
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Hinoi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takarada
authors.forename: Sayumi
authors.initials: S
authors.lastname: Fujimori
authors.forename: Liyang
authors.initials: L
authors.lastname: Wang
authors.forename: Mika
authors.initials: M
authors.lastname: Iemata
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Uno
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D002356:Cartilage / Q000166:cytology / Q000196:embryology; D002454:Cell Differentiation; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D024121:Collagen Type X / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D051379:Mice; D051267:NF-E2-Related Factor 2 / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology; D053495:Osteopontin / Q000378:metabolism; D013977:Tibia / Q000166:cytology / Q000196:embryology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D024121:Collagen Type X; D003598:Cytoskeletal Proteins; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C506896:Spp1 protein, mouse; D053495:Osteopontin