Molecular mechanism of mammalian biological rhythms

几乎所有的生物都有大约24小时的昼夜节律。昼夜节律是在起搏器细胞中产生的，并受到环境信号的影响，如光和温度。昼夜节律振荡的输出表现为运动活动、激素分泌、陡峭的尾流周期和许多生理功能。最近的分子解剖揭示，反馈环是昼夜节律振荡器的基本概念，从脉孢子虫和果蝇到小鼠，都是保守的。1)为了阐明哺乳动物时钟基因在体内的功能，我们将哺乳动物的Per基因引入果蝇Tim启动子下的空突变体per0中，并在一些克隆中发现了活体挽救。2)我们分离了人hPer3的cDNA和基因组，并与mPer3、可变数目串联重复序列(VNTR)、剪接变异体(SVS)和单核苷酸多态(SNPs)进行了比较。3)通过差异显示的方法分离到了一个新的锌指型转录因子(Lot1)。4)血清休克培养的N1H3T3细胞有mPER2和mPER3蛋白的昼夜节律性表达，但没有TIM蛋白的节律性表达。

Almost all organisms have their circadian rhythms with periods of approximately 24 hours. Circadian rhythms are generated in pacemaker cells and are entrained by environmental cues, such as light and temperature. The output of a circadian oscillation appears as locomotive activity, hormonal secretion, the steep-wake cycle, and many physiological functions. Recent molecular dissection has revealed that the feedback loop is the basic concept of the circadian oscillator, conserved across the species from Neurospora and Drosophila to mice. We have isolated a mammalian homologue of clock genes from the mouse brain.1) To clarify the in vivo function of mammalian clock genes, we introduced the mammalian Per genes under Drosophila tim promoter into the null mutant per0 and have found in vivo rescue in some colonies.2) We isolated human hPer3 cDNA and genome and found, compared with mPer3, VNTR (variable number of tandem repeats), SVs (splicing variants) and SNPs (single nucleotide polymorphisms).3) We isolated a new zinc-finger type of transcription factor (Lot1) by differential display method. The Lot1 mRNA is highly expressed in SCN, the mammalian circadian center, during P1 to P10.4) We showed expression of mPER2 and mPER3 protein in a circadian manner by serum shock to cultured N1H3T3 cells, but no rhythmic expression of TIM proteins.