Van Gelder R N, Krasnow M A
Department of Biochemistry, Stanford University School of Medicine, CA 94305, USA.
EMBO J. 1996 Apr 1;15(7):1625-31.
The Drosophila melanogaster period (per) gene is required for expression of endogenous circadian rhythms of locomotion and eclosion. per mRNA is expressed with a circadian rhythm that is dependent on Per protein; this feedback loop has been proposed to be essential to the central circadian pacemaker. This model would suggest the Per protein also controls the circadian expression of other genetic loci to generate circadian behavior and physiology. In this paper we describe Dreg-5, a gene whose mRNA is expressed in fly heads with a circadian rhythm nearly identical to that of the per gene. Dreg-5 mRNA continues to cycle in phase with that of per mRNA in conditions of total darkness and also when the daily feeding time is altered. Like per mRNA, Dreg-5 mRNA is not expressed rhythmically in per null mutant flies. Dreg-5 encodes a novel 298 residue protein and Dreg-5 protein isoforms also oscillate in abundance with a circadian rhythm. The phase of Dreg-5 protein oscillation, however, is different from that of Per protein expression, suggesting that Dreg-5 and per have common translational but different post-translational control mechanisms. These results demonstrate that the per gene is capable of modulating the rhythmic expression of other genes; this activity may form the basis of the output of circadian rhythmicity in Drosophila.
果蝇的周期（per）基因是内源性运动和羽化昼夜节律表达所必需的。per mRNA以依赖于Per蛋白的昼夜节律表达；这种反馈回路被认为是中央昼夜节律起搏器所必需的。该模型表明，Per蛋白还控制其他基因位点的昼夜表达，以产生昼夜行为和生理现象。在本文中，我们描述了Dreg-5，一种mRNA在蝇头中以与per基因几乎相同的昼夜节律表达的基因。在完全黑暗的条件下以及每日喂食时间改变时，Dreg-5 mRNA继续与per mRNA同步循环。与per mRNA一样，Dreg-5 mRNA在per基因缺失的突变果蝇中无节律性表达。Dreg-5编码一种新的298个残基的蛋白质，Dreg-5蛋白异构体也以昼夜节律丰度振荡。然而，Dreg-5蛋白振荡的相位与Per蛋白表达的相位不同，这表明Dreg-5和per具有共同的翻译控制机制，但翻译后控制机制不同。这些结果表明，per基因能够调节其他基因的节律性表达；这种活性可能构成果蝇昼夜节律输出的基础。
