Endogenous circannual clock and HP complex in a hibernation control system.
Hibernation in mammals is a mysterious biological phenomenon that appears on a seasonal basis for surviving a potentially lethal low body temperature (Tb) near 0 degrees C and protecting organisms from various diseases and harmful events during hibernation. The exact mechanism by which such a unique ability is seasonally developed is still unknown. On the basis of our previous finding that the source of calcium ions for excitation-contraction coupling in myocardium of chipmunks, a rodent hibernator, is seasonally modulated for hibernation, the liver-derived hibernation-specific protein (HP) complex was discovered. Recently, the HP complex was identified as a promising candidate hormone that carries a hibernation signal to the brain independently of Tb and environmental changes for developing a capacity for tolerating low Tb. This finding will promote new approaches to understanding biological hibernation systems, including a circannual clock and its signaling pathway between the brain and the periphery. A new definition of hibernation and a possible model of a hibernation control system are proposed.
Kondo
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Mitsubishi Kagaku Institute of Life Sciences, Machida, Tokyo 194-8511, Japan.
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D001798:Blood Proteins / Q000737:chemistry / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D001921:Brain / Q000502:physiology; D020013:Calcium Signaling; D002940:Circadian Rhythm / Q000502:physiology; D006321:Heart / Q000502:physiology; D006605:Hibernation / Q000502:physiology*; D008954:Models, Biological; D046912:Multiprotein Complexes; D012589:Sciuridae / Q000502:physiology*; D012621:Seasons; D015398:Signal Transduction
D001798:Blood Proteins; D046912:Multiprotein Complexes