Tanimura Akihiko, Nezu Akihiro, Morita Takao, Murata Kaori
Department of Pharmacology, School of Dentistry, Health Sciences University of Hokkaido.
Department of Biochemistry, The Nippon Dental University, School of Life Dentistry at Niigata.
Nihon Yakurigaku Zasshi. 2018;152(1):21-27. doi: 10.1254/fpj.152.21.
Inositol 1,4,5-trisphosphate (IP) is an important intracellular messenger produced by phospholipase C via the activation of G-protein-coupled receptor- or receptor-tyrosine-kinase-mediated pathways, and is involved in numerous responses to hormones, neurotransmitters, and growth factors through the releases of Ca from intracellular stores via IP receptors. IP-mediated Ca signals often exhibit complex spatial and temporal organizations, such as Ca oscillations. Recently, new methods have become available to measure IP concentration ([IP]) using AlphaScreen technology, fluorescence polarization, and competitive ligand binding assay (CFLA). These methods are useful for the high throughput screening in drug discovery. Calcium ions generate versatile intracellular signals such as Ca oscillations and waves. Fluorescent sensors molecules to monitor changes in [IP] in single living cells are crucial to study the mechanism for the spatially and temporally regulated Ca signals. In particular, FRET-based IP sensors are useful for the quantitative monitoring intracellular [IP], and allowed to uncovered the oscillatory IP dynamics in association with Ca oscillations. A mathematical model of coupled Ca and IP oscillations predicts that Ca oscillations are the result of modulation of the IP receptor by intracellular Ca, and that the period is modulated by the accompanying IP oscillations. These model predictions have also been confirmed experimentally. At present, however, usefulness of FRET-based IP sensors are limited by their relatively small change in fluorescence. Development of novel IP sensors with improve dynamic range would be important for understanding the regulatory mechanism of Ca signaling and for in vivo IP imaging.
肌醇1,4,5-三磷酸（IP）是磷脂酶C通过激活G蛋白偶联受体或受体酪氨酸激酶介导的途径产生的一种重要的细胞内信使，它通过IP受体从细胞内储存中释放Ca，参与对激素、神经递质和生长因子的多种反应。IP介导的Ca信号通常表现出复杂的空间和时间组织，如Ca振荡。最近，已经有了使用AlphaScreen技术、荧光偏振和竞争性配体结合测定（CFLA）来测量IP浓度（[IP]）的新方法。这些方法对于药物发现中的高通量筛选很有用。钙离子产生多种细胞内信号，如Ca振荡和波。用于监测单个活细胞中[IP]变化的荧光传感器分子对于研究空间和时间调节的Ca信号机制至关重要。特别是，基于荧光共振能量转移（FRET）的IP传感器对于定量监测细胞内[IP]很有用，并能够揭示与Ca振荡相关的振荡IP动态。Ca和IP振荡耦合的数学模型预测，Ca振荡是细胞内Ca对IP受体调节的结果，并且周期受伴随的IP振荡调节。这些模型预测也已通过实验得到证实。然而，目前基于FRET的IP传感器的实用性受到其相对较小的荧光变化的限制。开发具有改善动态范围的新型IP传感器对于理解Ca信号的调节机制和体内IP成像很重要。
