CRAC Channels Drive Digital Activation and Provide Analog Control and Synergy to Ca2+-Dependent Gene Regulation
CRAC Channels Drive Digital Activation and Provide Analog Control and Synergy to Ca2+-Dependent Gene Regulation
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DOI：
10.1016/j.cub.2011.12.025
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发表时间：
2012-02-07
期刊：
影响因子：
9.2
通讯作者：
Parekh, Anant B.
中科院分区：
文献类型：
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作者：
Kar, Pulak;Nelson, Charmaine;Parekh, Anant B.
Ca 2+依赖性基因表达对细胞生长、增殖、可塑性和适应性至关重要[1-3]。由于脊椎动物中将细胞质Ca 2+信号与蛋白质合成的激活联系起来的常见机制涉及转录因子的活化T细胞核因子（NFAT）家族[4，5]，因此我们通过使用遗传编码的荧光蛋白的NFAT驱动的表达来量化生理Ca 2+信号后单细胞中的蛋白质表达。我们发现，CRAC通道激活后的基因表达是一个全有或全无的事件在一定范围内的刺激强度。增加激动剂浓度招募更多的细胞，但每个响应细胞基本上以数字方式这样做。此外，Ca 2+依赖的基因表达显示出短期记忆和强协同作用，其中两个单独无效的激动剂脉冲稳健地激活基因表达，前提是它们之间的时间间隔短。这样的时间过滤赋予重合检测Ca 2+依赖性基因激活。潜在的分子基础映射到时间依赖性，非线性积累的核NFAT。CRAC通道附近的局部Ca 2+必须升高到阈值水平以上以驱动基因表达，为数字激活过程提供模拟控制，并提供一种从激活转录中滤除背景噪声波动的方法，同时确保激发-转录偶联机制的稳健性和高保真度。
Ca2+-dependent gene expression is critical for cell growth, proliferation, plasticity, and adaptation [1-3]. Because a common mechanism in vertebrates linking cytoplasmic Ca2+ signals with activation of protein synthesis involves the nuclear factor of activated T cells (NFAT) family of transcription factors [4, 5], we have quantified protein expression in single cells following physiological Ca2+ signals by using NFAT-driven expression of a genetically encoded fluorescent protein. We find that gene expression following CRAC channel activation is an all-or-nothing event over a range of stimulus intensities. Increasing agonist concentration recruits more cells but each responding cell does so in an essentially digital manner. Furthermore, Ca2+-dependent gene expression shows both short-term memory and strong synergy, where two pulses of agonist, which are ineffectual individually, robustly activate gene expression provided that the time interval between them is short. Such temporal filtering imparts coincidence detection to Ca2+-dependent gene activation. The underlying molecular basis mapped to time-dependent, nonlinear accumulation of nuclear NFAT. Local Ca2+ near CRAC channels has to rise above a threshold level to drive gene expression, providing analog control to the digital activation process and a means to filter out fluctuations in background noise from activating transcription while ensuring robustness and high fidelity in the excitation-transcription coupling mechanism.