Nuclear proton dynamics and interactions with calcium signaling
Nuclear proton dynamics and interactions with calcium signaling
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DOI：
10.1016/j.yjmcc.2015.07.003
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发表时间：
2016-07-01
影响因子：
5
通讯作者：
Swietach, Pawel
中科院分区：
文献类型：
--
作者：
Hulikova, Alzbeta;Swietach, Pawel
作用于细胞核的生化信号可以调节基因表达。尽管核酸和核蛋白（例如转录因子）对质子具有固有的亲和力，但对调节核pH（pH（nuc））的机制以及如何利用这些机制来控制基因表达知之甚少。在这里，我们表明，pH值（nuc）动态可以使用DNA结合染料Hoechst 33342成像。核孔允许中等大小的分子（钙黄绿素）通过，但是质子必须首先结合到移动的缓冲液以获得进入核质。基于由光解H +-解开或暴露于弱酸/碱引起的pH（nuc）瞬变的大幅度，估计存在于透化细胞的核中的固定缓冲非常弱。因此，大部分核pH缓冲以移动的缓冲液的形式来源于细胞质。有效的质子扩散是更快的核质比在细胞质中，在协议与较高的移动到固定的缓冲比在细胞核中。心肌细胞pH值（nuc）的变化，改变核Ca2+信号的演习。阻断1，4，5-三磷酸肌醇受体的Ca 2+释放可稳定碱化细胞核。这种Ca2 +-pH相互作用可能是由与常见化学部分的竞争性结合引起的。与移动的缓冲液的竞争性结合可以将Ca 2+经由核孔的流出与质子的逆流偶联。这将在细胞质和细胞核之间产生稳定的pH梯度，其对细胞核Ca2+信号传导的状态敏感。质子在核中的异常行为为调节心脏核生物学提供了新的机制。(C)2015作者爱思唯尔有限公司出版
Biochemical signals acting on the nucleus can regulate gene expression. Despite the inherent affinity of nucleic acids and nuclear proteins (e.g. transcription factors) for protons, little is known about the mechanisms that regulate nuclear pH (pH(nuc)), and how these could be exploited to control gene expression. Here, we show that pH(nuc) dynamics can be imaged using the DNA-binding dye Hoechst 33342. Nuclear pores allow the passage of medium-sized molecules (calcein), but protons must first bind to mobile buffers in order to gain access to the nucleoplasm Fixed buffering residing in the nucleus of permeabilized cells was estimated to be very weak on the basis of the large amplitude of pH(nuc) transients evoked by photolytic H+-uncaging or exposure to weak acids/bases. Consequently, the majority of nuclear pH buffering is sourced from the cytoplasm in the form of mobile buffers. Effective proton diffusion was faster in nucleoplasm than in cytoplasm, in agreement with the higher mobile-to-fixed buffering ratio in the nucleus. Cardiac myocyte pH(nuc) changed in response to maneuvers that alter nuclear Ca2+ signals. Blocking Ca2+ release from inositol-1,4,5-trisphosphate receptors stably alkalinized the nucleus. This Ca2+-pH interaction may arise from competitive binding to common chemical moieties. Competitive binding to mobile buffers may couple the efflux of Ca2+ via nuclear pores with a counterflux of protons. This would generate a stable pH gradient between cytoplasm and nucleus that is sensitive to the state of nuclear Ca2+ signaling. The unusual behavior of protons in the nucleus provides new mechanisms for regulating cardiac nuclear biology. (C) 2015 The Authors. Published by Elsevier Ltd.