Circadian and photic regulation of MAP kinase by Ras- and protein phosphatase-dependent pathways in the chick pineal gland.
Chick pineal mitogen-activated protein kinase (MAPK) exhibits circadian activation and light-dependent deactivation at nighttime. Here we report that, in the chick pineal gland, levels of active forms of MAPK, MEK, Raf-1 and Ras exhibited synchronous circadian rhythms with peaks during the subjective night, suggesting a sequential activation of components in the classical Ras-MAPK pathway in a circadian manner. In contrast, the light-dependent deactivation of MAPK was not accompanied by any change of MEK activity, but it was attributed to the light-dependent activation of protein phosphatase dephosphorylating MAPK. These results indicate that the photic and clock signals regulate MAPK activity via independent pathways, and suggest a pivotal role of MAPK in photic entrainment and maintenance of the circadian oscillation.
Hayashi
Y
Y
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
Sanada
K
K
Fukada
Y
Y
D000818:Animals; D002645:Chickens; D002940:Circadian Rhythm; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D011905:Genes, ras; D015151:Immunoblotting; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017440:Photoperiod; D010870:Pineal Gland / Q000201:enzymology / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism*
D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases