Circadian production of melatonin in cartilage modifies rhythmic gene expression

Shanqi Fu, Miho Kuwahara, Yoko Uchida, Sei Kondo, Daichi Hayashi, Yuji Shimomura, Asami Takagaki, Takashi Nishida, Yusuke Maruyama, Mika Ikegame, Atsuhiko Hattori, Satoshi Kubota, Takako Hattori

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


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 BALB/c mouse chondrocytes caused enhanced cell growth and increased expression of Col2a1, Aggrecan and Sox9, but inhibited Col10a1 expression. 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.

Original languageEnglish
Pages (from-to)161-173
Number of pages13
JournalJournal of Endocrinology
Issue number2
Publication statusPublished - 2019


  • Arylalkylamine N-acetyltransferase (AANAT)
  • Cell growth
  • Chondrocyte
  • Circadian rhythm
  • Mass spectrometry (MS)
  • Melatonin
  • Skeletal growth

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology


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