Peripheral clocks and their role in circadian timing: insights from insects
Peripheral clocks and their role in circadian timing: insights from insects
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DOI：
10.1098/rstb.2001.0960
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发表时间：
2001-11-29
影响因子：
6.3
通讯作者：
Giebultowicz, JM
中科院分区：
文献类型：
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作者：
Giebultowicz, JM
最近在我们对细胞自主昼夜节律反馈回路的分子基础的理解方面取得了令人印象深刻的进展;然而，对昼夜节律系统的整体组织知之甚少。在多细胞动物（如昆虫）中有多少个时钟在滴答作响，它们的作用和它们之间的关系是什么？大多数试图定位包含生物钟的组织的尝试都是基于对行为节律的分析，并在各种动物中确定了位于大脑中的计时中心。几个重要的时钟基因的特征和他们的表达模式的分析表明，时钟的分子组成部分不仅在大脑中，而且在果蝇和其他昆虫以及脊椎动物的许多外周器官中是活跃的。随后的实验表明，离体外周器官可以在体外维持时钟基因的自我维持和光敏循环。这一点，再加上早期的证据表明，生理输出节律持续存在于孤立的器官和组织中，为昆虫和其他动物中存在功能自主的局部昼夜节律钟提供了强有力的证据。复杂动物的昼夜节律系统可能包括许多具有组织特异性功能和不同程度自主性的外周时钟，这似乎与它们对外部夹带信号的敏感性相关。
Impressive advances have been made recently in our understanding of the molecular basis of the cell-autonomous circadian feedback loop; however, much less is known about the overall organization of the circadian systems. How many clocks tick in a multicellular animal, such as an insect, and what are their roles and the relationships between them? Most attempts to locate clock- containing tissues were based on the analysis of behavioural rhythms and identified brain-located timing centres in a variety of animals. Characterization of several essential clock genes and analysis of their expression patterns revealed that molecular components of the clock are active not only in the brain, but also in many peripheral organs of Drosophila and other insects as well as in vertebrates. Subsequent experiments have shown that isolated peripheral organs can maintain self-sustained and light sensitive cycling of clock genes in vitro. This, together with earlier demonstrations that physiological output rhythms persist in isolated organs and tissues, provide strong evidence for the existence of functionally autonomous local circadian clocks in insects and other animals. Circadian systems in complex animals may include many peripheral clocks with tissue-specific functions and a varying degree of autonomy, which seems to be correlated with their sensitivity to external entraining signals.