start-ver=1.4 cd-journal=joma no-vol=241 cd-vols= no-issue=2 article-no= start-page=161 end-page=173 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190301 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Circadian production of melatonin in cartilage modifies rhythmic gene expression en-subtitle= kn-subtitle= en-abstract= kn-abstract= Endochondral ossification, including bone growth and other metabolic events, is regulated by circadian rhythms. Herein, we provide evidence that melatonin has a direct effect on the circadian rhythm of chondrocytes. We detected mRNA expression of the genes which encode the melatonin-synthesizing enzymes AANAT (arylalkylamine N-acetyltransferase) and HIOMT (hydroxyindole O-methyltransferase), as well as the melatonin receptors MT1 and MT2 in mouse primary chondrocytes and cartilage. Production of melatonin was confirmed by mass spectrometric analysis of primary rat and chick chondrocytes. Addition of melatonin to primary mouse chondrocytes caused enhanced cell growth and increased expression of Col2a1, Aggrecan, and Sox9, but inhibited Col10a1 expression in primary BALB/c mouse chondrocytes. Addition of luzindole, an MT1 and MT2 antagonist, abolished these effects. These data indicate that chondrocytes produce melatonin, which regulates cartilage growth and maturation via the MT1 and MT2 receptors. Kinetic analysis showed that melatonin caused rapid upregulation of Aanat, Mt1, Mt2, and Pthrp expression, followed by Sox9 and Ihh. Furthermore, expression of the clock gene Bmal1 was induced, while that of Per1 was downregulated. Chronobiological analysis of synchronized C3H mouse chondrocytes revealed that melatonin induced the cyclic expression of Aanat and modified the cyclic rhythm of Bmal1, Mt1, and Mt2. In contrast, Mt1 and Mt2 showed different rhythms from Bmal1 and Aanat, indicating the existence of different regulatory genes. Our results indicate that exogenous and endogenous melatonin work in synergy in chondrocytes to adjust rhythmic expression to the central suprachiasmatic nucleus clock. en-copyright= kn-copyright= en-aut-name=FuShanqi en-aut-sei=Fu en-aut-mei=Shanqi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KuwaharaMiho en-aut-sei=Kuwahara en-aut-mei=Miho kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=UchidaYoko en-aut-sei=Uchida en-aut-mei=Yoko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KondoSei en-aut-sei=Kondo en-aut-mei=Sei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=HayashiDaichi en-aut-sei=Hayashi en-aut-mei=Daichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ShimomuraYuji en-aut-sei=Shimomura en-aut-mei=Yuji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=TakagakiAsami en-aut-sei=Takagaki en-aut-mei=Asami kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=NishidaTakashi en-aut-sei=Nishida en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=MaruyamaYusuke en-aut-sei=Maruyama en-aut-mei=Yusuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=IkegameMika en-aut-sei=Ikegame en-aut-mei=Mika kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=HattoriAtsuhiko en-aut-sei=Hattori en-aut-mei=Atsuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=KubotaSatoshi en-aut-sei=Kubota en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=HattoriTakako en-aut-sei=Hattori en-aut-mei=Takako kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= affil-num=1 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=2 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=3 en-affil=Department of Preventive Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=4 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=5 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=6 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=7 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=8 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=9 en-affil=Department of Biology, College of Liberal Arts and Sciences, Tokyo Medical and Dental University kn-affil= affil-num=10 en-affil=Department of Oral Morphology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=11 en-affil=Department of Biology, College of Liberal Arts and Sciences, Tokyo Medical and Dental University kn-affil= affil-num=12 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=13 en-affil=Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= END