Hatori Megumi, Okano Toshiyuki, Nakajima Yoshito, Doi Masao, Fukada Yoshitaka
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
J Neurochem. 2006 Mar;96(6):1790-800. doi: 10.1111/j.1471-4159.2006.03712.x.
The circadian clock is an autonomous biological clock that is entrainable to environmental 24-h cycles by receiving time cues such as light. Generally, light given at early and late subjective night, respectively, delays and advances the phase of the circadian oscillator. We previously searched for the chicken pineal genes that are induced by light in a phase-dependent manner. The present study undertook cDNA cloning and characterization of a gene whose expression was remarkably up-regulated by light at late subjective night. The mRNA level of this gene exhibited robust diurnal change in the pineal gland, with a peak in the early (subjective) day under light-dark cycles and constant dark condition, and hence it was designated Lcg (Light-inducible and Clock-controlled Gene). Chicken Lcg encodes a coiled-coil protein composed of 560 amino acid residues. Among chicken tissues, the pineal gland and the retina exhibited relatively high expression levels of LCG. LCG was colocalized with gamma-tubulin, a centrosomal protein, when expressed in COS7 cells, and LCG is the first example of a clock-related molecule being accumulated at the centrosome. Coimmunoprecipitation of LCG with gamma-tubulin in the chicken pineal lysate suggests a link between the circadian oscillator and the centrosomal function.
昼夜节律钟是一种自主生物钟，通过接收诸如光等时间线索可与环境24小时周期同步。一般来说，分别在主观夜间早期和晚期给予的光会延迟和提前昼夜节律振荡器的相位。我们之前寻找过以相位依赖方式被光诱导的鸡松果体基因。本研究对一个基因进行了cDNA克隆和特征分析，该基因的表达在主观夜间晚期被光显著上调。该基因的mRNA水平在松果体中呈现出强烈的昼夜变化，在明暗周期和持续黑暗条件下，在（主观）白天早期达到峰值，因此它被命名为Lcg（光诱导和时钟控制基因）。鸡Lcg编码一种由560个氨基酸残基组成的卷曲螺旋蛋白。在鸡的组织中，松果体和视网膜表现出相对较高水平的LCG表达。当在COS7细胞中表达时，LCG与中心体蛋白γ-微管蛋白共定位，并且LCG是第一个在中心体积累的时钟相关分子的例子。鸡松果体裂解物中LCG与γ-微管蛋白的免疫共沉淀表明昼夜节律振荡器与中心体功能之间存在联系。
