Molecular Basis of Circadian Cytosolic Calcium Rhythms

2007 Fiscal Year Final Research Report Summary

• Project/Area Number: 16300104
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Neuroscience in general
• Research Institution: University of Toyama (2005-2007); Osaka Bioscience Institute (2004)
• Principal Investigator: IKEDA Masayuki University of Toyama, Graduate School of Science and Engineering(Science), Associate Professor (10288053)
• Project Period (FY): 2004 – 2007
• Keywords: Brain Slice Cultures / Clock Genes / Suprachiasmatic Nucleus / FRET / Cytosolic Calcium

Research Abstract

The hypothalamic suprachiasmatic nucleus (SCN) has a pivotal role for the mammalian circadian clock system. We have demonstrated circadian rhythms in cytosolic Ca^(2+) concentrations in cultured SCN neurons and proposed that intracellular Ca^(2+) is a candidate messenger which mediates cellular input/output signals to/from the molecular loop. However, essential regulatory genes to drive circadian Ca^(2+) rhythms were currently unknown. The present research aims to elucidate the molecular mechanism underlying the generation of circadian Ca^(2+) rhythms in clock cells. First, we examined effects of mPer1/mPer2 antisense mRNAs on SCN neurons whereas failed to observe their effects on circadian rhythms in cytosolic Ca^(2+) and action potential firings. Second, we used several gene knockout mice lacking clock genes. The SCN neurons from the Cry1/Cry2 double knockout mice represented arrhythmic Ca^(2+) oscillations and those from the RORα knockout mice represented reduced amplitude Ca^(2+) o scillations. Thus, we further over-expressed native mouse Bmal1 or dominant negative Bmal1 into the SCN. These treatments resulted in a significant reduction in circadian Ca^(2+) oscillations in SCN neurons. Therefore, we concluded that endogenous expression of BMAL1 is essential for the generation of circadian Ca^(2+) rhythms and thus for the physiological activity rhythms in SCN neurons.
The present study also analyzed process of photic inputs to SCN neurons regarding the mobilization of cytosolic Ca^(2+) and expression of clock genes. We found light-pulse-induced mPer1/2 gene expression in the SCN and behavioral-phase-shifts were significantly reduced in cholecystokinin (CCK)-A receptor knockout mice. We demonstrated that CCK-A receptors were located predominately on glycinergic amacrine cells, but not retino-recipient SCN neurons. Moreover, Ca^(2+) imaging analysis demonstrated that the CCK-A agonist, CCK-8s, mobilized intracellular Ca^(2+) in amacrine cells but not retino-recipent SCN neurons. These data indicate a novel function of CCK-A receptors as part of the cellular mechanism underlying circadian photo-entrainment via amacrine-cell-mediated signal transduction pathways.

Research Products

• [Journal Article] Cholecystokinin-A receptors regulate photic input pathways to the circadian clock. (2008)
  • Author(s): Shimazoe T, Morita M, Ogiwara S, Kojiya T, Goto J, Kamakura M, Moriya T, Shinohara K, Takiguchi S, Kono A, Miyasaka K, Funakoshi A, & Ikeda M
  • Journal Title: The FASEB Journal 22 Pages: 1479-1490
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] (2008)Cholecystokinin-A receptors regulate photic input pathways to the circadian clock (2008)
  • Author(s): Shimazoe, T, Morita, M, Ogiwara, S, Kojiya, T, Goto, J, Kamakura, M, Moriya, T, Shinohara, K, Takiguchi, S, Kono, A, Miyasaka, K, Funakoshi, A, Ikeda, M^<CA>
  • Journal Title: The FASEB Journal 22 Pages: 1479-1490
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Role of nociceptin and opioid receptor like 1(ORL1)on entrainment function in the rat suprachiasmatic nucleus (2006)
  • Author(s): Sugino, T, Shimazoe, T^<CA>, Kanemoto, Y, Ikeda M, Watanabe, S
  • Journal Title: Neuroscience 137 Pages: 537-544
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Brain oxidation is an initial process in sleep induction. (2005)
  • Author(s): Ikeda M, Ikeda-Sagara M, Okada T, Clement P, Urade Y, Nagai T, Sugiyama T, Yoshioka T, Honda K, & Inoue S
  • Journal Title: Neuroscience 130 Pages: 1029-1040
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Brain oxidation is an initial process in sleep induction (2005)
  • Author(s): Ikeda, M^<CA>, Ikeda-Sagara, M, Okada, T, Clement, P, Urade, Y, Nagai, T, Sugiyama, T, Yoshioka, T, Honda K, Inoue, S
  • Journal Title: Neuroscience Vol. 130, No. 4 Pages: 1029-1040
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] mPer2 antisense oligonucleotides inhibit mPER2 expression but not circadian rhythms of physiological activity in cultured suprachias matic nucleus neurons (2004)
  • Author(s): Sugiyama T, Yoshioka T, & Ikeda M
  • Journal Title: Biochem. Biophys. Res. Commun. 323 Pages: 479-483
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] mPer2 antisense oligonucleotides inhibit mPER2 expression but not circadian rhythms of physiological activity in cultured suprachiasmatic nucleus neurons (2004)
  • Author(s): Sugiyama, T, Yoshioka, T, Ikeda, M^<CA>
  • Journal Title: Biochemical Biophysical Research Communications 323 Pages: 479-483
  • Description: 「研究成果報告書概要(欧文)」より
• [Presentation] Discovery of circadian intracellular Ca^<2+>waves in SCN neurons and its impact on the mammalian clock system. (2005)
  • Author(s): 池田真行
  • Organizer: ゴードンカンファレンス
  • Place of Presentation: ロードアイランド
  • Year and Date: 20050731-0805
  • Description: 「研究成果報告書概要(和文)」より
• [Presentation] Discovery of circadian intracellular Ca^(2+)waves in SCN neurons and its impact on the mammalian clock system. Total of 25 presentations during 2004-2007 (2005)
  • Author(s): Masayuki, Ikeda
  • Organizer: Gordon Conference Invited Speaker
  • Place of Presentation: Rhode island, USA
  • Year and Date: 20050731-0805
  • Description: 「研究成果報告書概要(欧文)」より
• [Book] 時間生物学事典 (2008)
  • Author(s): 池田真行
  • Total Pages: 340
  • Publisher: 朝倉書房
  • Description: 「研究成果報告書概要(和文)」より