Mouse dexamethasone-induced RAS protein 1 gene is expressed in a circadian rhythmic manner in the suprachiasmatic nucleus

• Published in: Brain research. Molecular brain research. 2003-01, Vol.110 (1), p.1-6
• Main Authors: Takahashi, Hirokazu, Umeda, Nanae, Tsutsumi, Yoko, Fukumura, Ryutaro, Ohkaze, Hajime, Sujino, Mitsugu, van der Horst, Gijsbertus, Yasui, Akira, Inouye, Shin-Ichi T, Fujimori, Akira, Ohhata, Tatsuya, Araki, Ryoko, Abe, Masumi
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chronobiology; Circadian rhythm; Circadian Rhythm - genetics; Cryptochromes; Dexamethasone; Dexras1; Drosophila Proteins; Eye Proteins; Flavoproteins - genetics; Fundamental and applied biological sciences. Psychology; G protein; Gene Expression Regulation; GTP-Binding Proteins; In Situ Hybridization; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Monomeric GTP-Binding Proteins - genetics; Monomeric GTP-Binding Proteins - metabolism; Photoreceptor Cells, Invertebrate; Polymerase Chain Reaction - methods; ras Proteins; Real-time PCR; Receptors, G-Protein-Coupled; RNA, Messenger - analysis; Suprachiasmatic nucleus; Suprachiasmatic Nucleus - physiology; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/S0169-328X(02)00543-0

We identified the Dexamethasone-induced RAS protein 1 ( Dexras1) gene as a cycling gene in the suprachiasmatic nucleus (SCN). Investigation of the whole brain using in situ hybridization demonstrated the localization of the expression of the gene in the SCN, thalamus, piriform cortex and hippocampus. However, rhythmic expression of the gene was observed only in the SCN. The rhythmic change in gene expression during 1 day was approximately five-fold, and the maximum expression was observed during subjective night. Real-time PCR using the SCN, paraventricular nucleus and cortex confirmed these results. Next, we analyzed the expression of the Dexras1 gene in the SCN of cryptochrome ( Cry) 1 and 2 double knockout mice. We found that the rhythmic expression disappeared. The results indicate that Dexras1 rhythmicity and levels are dependent upon CRYs. This is the first time that the G protein, which may be involved in the input pathway, has been isolated as a cycling gene in the SCN.