Chicken pineal Cry genes: light-dependent up-regulation of cCry1 and cCry2 transcripts

• Published in: Neuroscience letters Vol. 313; no. 1; pp. 13 - 16
• Main Authors: Yamamoto, Kazuyuki, Okano, Toshiyuki, Fukada, Yoshitaka
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 02.11.2001; Elsevier
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; Chicken; Chickens; Circadian clock; Circadian Rhythm - physiology; Clock gene; Cryptochrome; Cryptochromes; Darkness; Drosophila Proteins; Eye Proteins; Flavoproteins - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression - physiology; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Lighting; Molecular Sequence Data; Morphology. Functional localizations; Photoreceptor Cells, Invertebrate; Pineal gland; Pineal Gland - physiology; Receptors, G-Protein-Coupled; Transcription, Genetic - physiology; Transcriptional inhibitor; Vertebrates: endocrinology; Circadian clock; Chicken; Transcriptional inhibitor; Clock gene; Cryptochrome; Pineal gland; Vertebrata; Endocrine gland; Gene; Transcription; Pineal body; Biological rhythm; Inhibitor; Circadian rhythm; Aves; Aminoacid sequence
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/S0304-3940(01)02227-3

Vertebrate cryptochrome homologs (CRYs) are negative regulators for the transcription/translation-based autoregulatory feedback loop of the circadian clock. In this study we identified two Cry genes in the chicken, cCry1 and cCry2, which are expressed in the pineal gland. Messenger RNA levels of both cCry1 and cCry2 displayed circadian oscillation in cultured pineal cells under light/dark and constant darkness conditions. Noticeably, their mRNA levels during the light period were significantly higher than those in the dark, indicating light-dependent up-regulation of the two Cry genes mediated by photoreceptor(s) intrinsic to the chick pineal cells. These cCRYs inhibited E-box element-dependent cBMAL1/2-cCLOCK-induced transcription, suggesting that the chick pineal circadian oscillator is composed of molecules that are functionally similar to those of mammals but are subject to light-regulation distinct from the mammalian clockwork.