Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
J Neurochem. 2010 Nov;115(3):585-94. doi: 10.1111/j.1471-4159.2010.06953.x. Epub 2010 Sep 27.
In mammals, the retina contains a clock system that oscillates independently of the master clock in the suprachiasmatic nucleus and allows the retina to anticipate and to adapt to the sustained daily changes in ambient illumination. Using a combination of laser capture micro-dissection and quantitative PCR in the present study, the clockwork of mammalian photoreceptors has been recorded. The transcript amounts of the core clock genes Clock, Bmal1, Period1 (Per1), Per3, Cryptochrome2, and Casein kinase Iε in photoreceptors of rat retina have been found to undergo daily changes. Clock and Bmal1 peak with Per1 and Per3 around dark onset, whereas Casein kinase Iε and Cryptochrome2 peak at night. As shown for Clock, Per1, and Casein kinase Iε, the oscillation of transcript amounts results in daily changes of the protein products. The in-phase oscillation of Clock/Bmal1 with Pers and the rhythmic expression of Casein kinase Iε do not occur in molecular clocks of other tissues including the suprachiasmatic nucleus. Therefore, the findings presented suggest that the photoreceptor clock is unique not only in its position outside the clock hierarchy mastered by the suprachiasmatic nucleus, but also with regard to the intrinsic rhythmic properties of its molecular components.
在哺乳动物中，视网膜包含一个独立于视交叉上核主钟振荡的时钟系统，使视网膜能够预测和适应环境光照的持续日常变化。本研究采用激光捕获显微解剖和定量 PCR 的组合方法，记录了哺乳动物光感受器的时钟机制。发现大鼠视网膜光感受器中的核心时钟基因 Clock、Bmal1、Period1 (Per1)、Per3、Cryptochrome2 和 Casein kinase Iε 的转录物量呈现日变化。Clock 和 Bmal1 在黑暗开始时与 Per1 和 Per3 达到峰值，而 Casein kinase Iε 和 Cryptochrome2 在夜间达到峰值。如图所示 Clock、Per1 和 Casein kinase Iε，转录物量的振荡导致蛋白产物的日变化。Clock/Bmal1 与 Pers 的同相振荡和 Casein kinase Iε 的节律表达不会发生在包括视交叉上核在内的其他组织的分子钟中。因此，目前的研究结果表明，光感受器时钟不仅在其位于视交叉上核主导的时钟层次之外的位置上是独特的，而且在其分子成分的固有节律特性方面也是独特的。
