估計很多人都聽說過“生物鐘”，但知道“食物鐘”的人可能很少,。生物鐘以24小時為周期,，掌管著生物的“覺醒”與“睡眠”節(jié)奏。它受光線的控制,，其感受器分布在大腦超交叉神經核的下丘腦中,。生物鐘有“基于光照的生物節(jié)律器”之稱。
食物鐘負責進食,、消化和營養(yǎng)攝取,，通常與生物鐘同步，在白天和夜晚的運作程序幾乎與生物鐘相平行,。大腦,、胃和肝中都有感受器，可以接受食物傳遞的信號,，被稱為“食物相關的生物節(jié)律器”,。
看起來生物鐘似乎主導著食物鐘，但實際上受食物的誘導,，食物鐘可以“反客為主”,。人們早就知道生物鐘蛋白BMAL1，現在,，來自美國舊金山加州大學和德國馬普研究所的科學家又發(fā)現食物鐘蛋白PKCγ，并且弄清了食物鐘可以“凌駕”于生物鐘之上的原因,。
這篇近日發(fā)表在美國《國家科學院院刊》上的論文指出,，原來PKCγ可以結合BMAL1使其結構更穩(wěn)定，然后共同結合在時鐘蛋白上,，促進周期基因和隱色素基因的節(jié)律性轉錄,，由此產生食物鐘特有的時鐘效應。食物鐘的這種奇妙特性可以讓你快速倒時差,！
北京與紐約之間橫跨12個時區(qū),，倒時差通常需要一周左右,。由于生物鐘只能一天天地往前撥或向后撥，倒時差的速度如此之慢也就不足為奇了,。假如你能耐得住饑餓,，在旅行途中不吃不喝，然后在落地后大吃一頓,，你只要16個小時就能把時差倒過來!(生物谷Bioon.com)
doi: 10.1073/pnas.1218699110
PMC:
PMID:
PKCγ participates in food entrainment by regulating BMAL1
Luoying Zhanga, Diya Abrahama,b, Shu-Ting Lina, Henrik Osterb, Gregor Eicheleb, Ying-Hui Fua,1, and Louis J. Ptáčeka,c,1
Temporally restricted feeding (RF) can phase reset the circadian clocks in numerous tissues in mammals, contributing to altered timing of behavioral and physiological rhythms. However, little is known regarding the underlying molecular mechanism. Here we demonstrate a role for the gamma isotype of protein kinase C (PKCγ) in food-mediated entrainment of behavior and the molecular clock. We found that daytime RF reduced late-night activity in wild-type mice but not mice homozygous for a null mutation of PKCγ (PKCγ−/−). Molecular analysis revealed that PKCγ exhibited RF-induced changes in activation patterns in the cerebral cortex and that RF failed to substantially phase shift the oscillation of clock gene transcripts in the absence of PKCγ. PKCγ exerts effects on the clock, at least in part, by stabilizing the core clock component brain and muscle aryl hydrocarbon receptor nuclear translocator like 1 (BMAL1) and reducing its ubiquitylation in a deubiquitination-dependent manner. Taken together, these results suggest that PKCγ plays a role in food entrainment by regulating BMAL1 stability.
