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Open Access Research article

Rhythmic expression of Nocturnin mRNA in multiple tissues of the mouse

Yunxia Wang1, David L Osterbur2, Pamela L Megaw3, Gianluca Tosini4, Chiaki Fukuhara4, Carla B Green5 and Joseph C Besharse6*

Author Affiliations

1 PEL-FREEZ Clinical Systems, LLC, 9099 North Deerbrook Trail, Brown Deer, WI, 53223, USA

2 Biological Laboratories Library, Harvard University, 16 Divinity Ave, Cambridge, MA 02138, USA

3 School of Human and Biomedical Sciences, Division of Science and Design, University of Canberra, ACT 2601, Australia

4 Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA

5 Department of Biology and NSF Center for Biological Timing, University of Virginia, Charlottesville, USA

6 Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, USA

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BMC Developmental Biology 2001, 1:9  doi:10.1186/1471-213X-1-9

Published: 25 May 2001

Abstract

Background

Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis. Although encoding a novel protein, the nocturnin cDNA had strong sequence similarity with a C-terminal domain of the yeast transcription factor CCR4, and with mouse and human ESTs. Since its original identification others have cloned mouse and human homologues of nocturnin/CCR4, and we have cloned a full-length cDNA from mouse retina, along with partial cDNAs from human, cow and chicken. The goal of this study was to determine the temporal pattern of nocturnin mRNA expression in multiple tissues of the mouse.

Results

cDNA sequence analysis revealed a high degree of conservation among vertebrate nocturnin/CCR4 homologues along with a possible homologue in Drosophila. Northern analysis of mRNA in C3H/He and C57/Bl6 mice revealed that the mNoc gene is expressed in a broad range of tissues, with greatest abundance in liver, kidney and testis. mNoc is also expressed in multiple brain regions including suprachiasmatic nucleus and pineal gland. Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver.

Conclusion

The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector.