title: Up-regulation of per mRNA expression by parathyroid hormone through a protein kinase A-CREB-dependent mechanism in chondrocytes.
abstract: In bone, clock genes are involved in the circadian oscillation of bone formation and extracellular matrix expression. However, to date little attention has been paid to circadian rhythm in association with expression of clock genes during chondrogenesis in cartilage. In this study, we investigated the functional expression of different clock genes by chondrocytes in the course of cartilage development. The mRNA expression of types I, II, and X collagens exhibited a 24-h rhythm with a peak at zeitgeber time 6, in addition to a 24-h rhythmicity of all the clock genes examined in mouse femurs in vivo. Marked expression of different clock genes was seen in both osteoblastic MC3T3-E1 and chondrogenic ATDC5 cells in vitro, whereas parathyroid hormone (PTH) transiently increased period 1 (per1) mRNA expression at 1 h in both cell lines. Similar increases were seen in the mRNA levels for both per1 and per2 in prehypertrophic chondrocytes in metatarsal organotypic cultures within 2 h of exposure to PTH. PTH significantly activated the mouse per1 (mper1) and mper2 promoters but not the mper3 promoter in a manner sensitive to both a protein kinase A inhibitor and deletion of the cAMP-responsive element sequence (CRE) in ATDC5 cells. In HEK293 cells, introduction of brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (bmal1)/clock enhanced mouse type II collagen first intron reporter activity without affecting promoter activity, with reduction effected by either per1 or per2. These results suggest that PTH directly stimulates mper expression through a protein kinase A-CRE-binding protein signaling pathway for subsequent regulation of bmal1/clock-dependent extracellular matrix expression in cartilage.
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: Taichi
authors.initials: T
authors.lastname: Ueshima
authors.forename: Hironori
authors.initials: H
authors.lastname: Hojo
authors.forename: Mika
authors.initials: M
authors.lastname: Iemata
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takarada
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D002460:Cell Line; D019902:Chondrocytes / Q000201:enzymology / Q000378:metabolism*; D002940:Circadian Rhythm / Q000235:genetics; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D008297:Male; D008682:Metatarsal Bones / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D009924:Organ Culture Techniques; D010281:Parathyroid Hormone / Q000502:physiology*; D056950:Period Circadian Proteins; D012333:RNA, Messenger / Q000096:biosynthesis*; D013977:Tibia / Q000378:metabolism; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D024043:Collagen Type II; D017362:Cyclic AMP Response Element-Binding Protein; D009687:Nuclear Proteins; D010281:Parathyroid Hormone; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D056926:CLOCK Proteins; C538944:Clock protein, mouse; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases