Molecular mechanism of mammalian biological rhythms

几乎所有生物都有自己的昼夜节律，周期约为24小时。昼夜节律是由起搏器细胞产生的，并受光线和温度等环境因素的影响。昼夜节律振荡的输出表现为运动活动、激素分泌、陡尾周期和许多生理功能。最近的分子解剖揭示了反馈回路是昼夜节律振荡器的基本概念，在从神经孢子虫和果蝇到小鼠的物种中都是保守的。我们已经从老鼠的大脑中分离出了生物钟基因的哺乳动物同源物。1)为了明确哺乳动物时钟基因的体内功能，我们将果蝇tim启动子下的哺乳动物Per基因引入到零突变体per0中，并在一些菌落中发现了体内拯救。2)我们分离了人类hPer3的cDNA和基因组，发现与mPer3相比，有VNTR（可变数目串联重复序列）、SVs（剪接变异）和SNPs（单核苷酸多态性）。3)采用差分显示法分离到一种新的锌指型转录因子（Lot1）。在P1至P10.4期间，Lot1 mRNA在哺乳动物的昼夜节律中心SCN中高度表达。我们发现，通过血清冲击培养的N1H3T3细胞，mPER2和mPER3蛋白以昼夜节律的方式表达，但TIM蛋白没有节律性表达。

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.