open access

https://hdl.handle.net/2115/76003

Cryptochrome deficiency enhances transcription but reduces protein levels of pineal Aanat

英語

C3H mice

2018-11

BioScientifica

Journal of molecular endocrinology

61(4)

219-229

Cryptochrome (Cry) 1 and 2 are essential for circadian rhythm generation, not only in the suprachiasmatic nucleus, the site of the mammalian master circadian clock, but also in peripheral organs throughout the body. CRY is also known as a repressor of arylalkylamine-N-acetyltransferase (Aanat) transcription; therefore, Cry deficiency is expected to induce constantly high pineal melatonin content. Nevertheless, we previously found that the content was consistently low in melatonin-proficient Cry1 and Cry2 double-deficient mice (Cry1(-/-)/Cry2(-/-)) on C3H background. This study aims to clarify the mechanism underlying this discrepancy. In the Cry1(-/-)/Cry2(-/-) pineal, expression levels of Aanat and clock gene Per1 were consistently high with no circadian fluctuation on the first day in constant darkness, demonstrating that CRY acts in vivo as a repressor of the pineal circadian clock and AANAT. In contrast, the enzyme activity and protein levels of AANAT remained low throughout the day, supporting our previous observation of continuously low melatonin. Thus, effects of Cry deficiency on the responses of beta-adrenergic receptors were examined in cultured pineal glands. Isoproterenol, a beta-adrenergic stimulant, significantly increased melatonin content, although the increase was smaller in Cry1(-/-)/Cry2(-/-) than in WT mice, during both the day and night. However, the increase in cAMP in response to forskolin was similar in both genotypes, indicating that CRY deficiency does not affect the pathway downstream of the beta-adrenergic receptor. These results suggest that a lack of circadian adrenergic input due to CRY deficiency decreases beta-receptor activity and cAMP levels, resulting in consistently low AANAT levels despite abundant Aanat mRNA.

学術雑誌論文

Accepted Manuscript

Disclaimer: this is not the definitive version of record of this article. This manuscript has been accepted for publication in Journal of Molecular Endocrinology, but the version presented here has not yet been copy-edited, formatted or proofed. Consequently, Bioscientifica accepts no responsibility for any errors or omissions it may contain. The definitive version is now freely available at https://doi.org/10.1530/JME-18-0101 2018.

0952-5041

1479-6813

AA10675676