Hayashi Y, Sanada K, Fukada Y
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
FEBS Lett. 2001 Feb 23;491(1-2):71-5. doi: 10.1016/s0014-5793(01)02153-6.
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.
鸡松果体丝裂原活化蛋白激酶（MAPK）在夜间呈现昼夜节律性激活和光依赖性失活。在此我们报告，在鸡松果体中，MAPK、MEK、Raf-1和Ras的活性形式水平呈现同步的昼夜节律，在主观夜间达到峰值，提示经典Ras-MAPK途径中的组分以昼夜节律的方式进行顺序激活。相比之下，MAPK的光依赖性失活并未伴随MEK活性的任何变化，而是归因于使MAPK去磷酸化的蛋白磷酸酶的光依赖性激活。这些结果表明，光信号和生物钟信号通过独立途径调节MAPK活性，并提示MAPK在光诱导和昼夜节律振荡维持中起关键作用。
