Insect cryptochromes: Gene duplication and loss define diverse ways to construct insect circadian clocks
Insect cryptochromes: Gene duplication and loss define diverse ways to construct insect circadian clocks
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DOI：
10.1093/molbev/msm011
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发表时间：
2007-04-01
影响因子：
10.7
通讯作者：
Reppert, Steven M.
中科院分区：
文献类型：
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作者：
Yuan, Quan;Metterville, Danielle;Reppert, Steven M.
隐色素（CRY）蛋白是后生动物中央生物钟的组成部分。系统发育分析表明，在后生动物辐射的基部至少有2轮基因复制，以及一些缺失，产生了昆虫中2个隐色素基因家族，一个类似果蝇的cry1基因家族和一个类似脊椎动物的cry2基因家族。先前的研究表明，昆虫CRY1是光敏的，而光不敏感的CRY2可以有效抑制时钟相关的CLOCK: cycle介导的转录。本研究将CRY2的转录抑制功能扩展到膜翅目（蜜蜂Apis mellifera和大黄蜂Bombus impatiens）和鞘翅目（红粉甲虫Tribolium castaneum） 2目。重要的是，蜜蜂和甲虫的CRY2蛋白在培养过程中对光不敏感，无论是蛋白质水平的降解还是抑制转录反应，这表明api和Tribolium不含CRY1，因此有新的光输入途径进入它们的生物钟。通过将功能数据映射到隐色素/6-4光解酶基因树中，我们发现昆虫CRY2的转录抑制功能来自于光敏光解酶样祖先基因，可能缺乏抑制CLOCK: cycle介导的转录的能力。这些数据为提出新的昆虫生物钟机制提供了一个进化背景。
Cryptochrome (CRY) proteins are components of the central circadian clockwork of metazoans. Phylogenetic analyses show at least 2 rounds of gene duplication at the base of the metazoan radiation, as well as several losses, gave rise to 2 cryptochrome (cry) gene families in insects, a Drosophila-like cry1 gene family and a vertebrate-like cry2 family. Previous studies have shown that insect CRY1 is photosensitive, whereas photo-insensitive CRY2 functions to potently inhibit clock-relevant CLOCK:CYCLE-mediated transcription. Here, we extended the transcriptional repressive function of insect CRY2 to 2 orders-Hymenoptera (the honeybee Apis mellifera and the bumblebee Bombus impatiens) and Coleoptera (the red flour beetle Tribolium castaneum). Importantly, the bee and beetle CRY2 proteins are not light sensitive in culture, in either degradation of protein levels or inhibitory transcriptional response, suggesting novel light input pathways into their circadian clocks as Apis and Tribolium do not have CRY1. By mapping the functional data onto a cryptochrome/6-4 photolyase gene tree, we find that the transcriptional repressive function of insect CRY2 descended from a light-sensitive photolyase-like ancestral gene, probably lacking the ability to repress CLOCK:CYCLE-mediated transcription. These data provide an evolutionary context for proposing novel circadian clock mechanisms in insects.