NPAS2: An analog of clock operative in the mammalian forebrain
NPAS2: An analog of clock operative in the mammalian forebrain
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DOI：
10.1126/science.1060699
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发表时间：
2001-07-20
期刊：
影响因子：
56.9
通讯作者：
McKnight, SL
中科院分区：
文献类型：
--
作者：
Reick, M;Garcia, JA;McKnight, SL
神经元PAS结构域蛋白2（NPAS2）是主要在哺乳动物前脑中表达的转录因子。NPAS2在一级氨基酸序列上与Clock高度相关，Clock是一种在视交叉上核中表达的转录因子，其与BMAL 1异二聚化并调节昼夜节律。为了研究NPAS2的生物学作用，我们制备了能够条件诱导NPAS2：BMAL 1异二聚体的神经母细胞瘤细胞系，并通过代表性差异分析、DNA微阵列和北方印迹鉴定了推定的靶基因。共诱导NPAS2和BMAL1激活内源性Per1，Per2和Cry1基因的转录，这些基因编码昼夜节律调节装置的负激活成分，并抑制内源性BMAL1基因的转录。对保持在24小时光暗循环中的野生型小鼠额叶皮质的分析显示，Per1，Per2和Cry1 mRNA水平在黑暗期间升高，在光照期间降低，而BMAL1 mRNA显示相反的模式。在原位杂交实验中的小鼠保持在恒定的黑暗中显示，Per2 mRNA丰度并没有振荡的昼夜节律周期的函数在NPAS2缺陷小鼠。因此，NPAS2可能作为哺乳动物前脑中分子时钟的一部分发挥作用。
Neuronal PAS domain protein 2 (NPAS2) is a transcription factor expressed primarily in the mammalian forebrain. NPAS2 is highly related in primary amino acid sequence to Clock, a transcription factor expressed in the suprachiasmatic nucleus that heterodimerizes with BMAL1 and regulates circadian rhythm. To investigate the biological role of NPAS2, we prepared a neuroblastoma cell Line capable of conditional induction of the NPAS2:BMAL1 heterodimer and identified putative target genes by representational difference analysis, DNA microarrays, and Northern blotting. Coinduction of NPAS2 and BMAL1 activated transcription of the endogenous Per1, Per2, and Cry1 genes, which encode negatively activating components of the circadian regulatory apparatus, and repressed transcription of the endogenous BMAL1 gene. Analysis of the frontal cortex of wild-type mice kept in a 24-hour Light-dark cycle revealed that Per1, Per2, and Cry1 mRNA Levels were elevated during darkness and reduced during Light, whereas BMAL1 mRNA displayed the opposite pattern. In situ hybridization assays of mice kept in constant darkness revealed that Per2 mRNA abundance did not oscillate as a function of the circadian cycle in NPAS2-deficient mice. Thus, NPAS2 likely functions as part of a molecular clock operative in the mammalian forebrain.