Role of elementary Ca2+ puffs in generating repetitive Ca2+ oscillations
Role of elementary Ca2+ puffs in generating repetitive Ca2+ oscillations
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DOI：
10.1093/emboj/20.1.65
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发表时间：
2001-01-15
期刊：
影响因子：
11.4
通讯作者：
Parker, I
中科院分区：
文献类型：
--
作者：
Marchant, JS;Parker, I
肌醇 (1,4,5)-三磷酸 (IP3) 以局部“喷发”和以频率依赖方式编码信息的重复波的形式释放细胞内 Ca2+。使用视频速率共焦成像以及非洲爪蟾卵母细胞中 IP3 的光释放，我们研究了泡在确定全局 Ca2+ 波周期性中的作用。波频率不仅仅由细胞支持波传播的能力的周期性恢复来界定，还涉及通过波间期期间多个部位的抽吸频率和幅度的逐步增加而对 Ca2+ 诱导的 Ca2+ 释放的敏化，以及起搏器 Ca2+ 的积累，从而允许在“焦点”部位抽吸触发后续波。这些特定的“焦点”位点的特点是对 IP3 具有较高的敏感性，并且与邻近的喷发位点紧密相连，优先夹带 Ca2+ 波的时间频率和空间方向性。尽管许多随机喷发点的活动总和促进了规则周期性全局 Ca2+ 信号的生成，但单个 Ca2+ 喷发的特性控制着 Ca2+ 尖峰的动力学以及其局部微域中亚细胞尖峰的（更高）频率。
Inositol (1,4,5)-trisphosphate (IP3) liberates intracellular Ca2+ both as localized 'puffs' and as repetitive waves that encode information in a frequency-dependent manner. Using video-rate confocal imaging, together with photorelease of IP3 in Xenopus oocytes, we investigated the roles of puffs in determining the periodicity of global Ca2+ waves. Wave frequency is not delimited solely by cyclical recovery of the cell's ability to support wave propagation, but further involves sensitization of Ca2+-induced Ca2+ release by progressive increases in puff frequency and amplitude at numerous sites during the interwave period, and accumulation of pacemaker Ca2+, allowing a puff at a 'focal' site to trigger a subsequent wave. These specific 'focal' sites, distinguished by their higher sensitivity to IP3 and close apposition to neighboring puff sites, preferentially entrain both the temporal frequency and spatial directionality of Ca2+ waves. Although summation of activity from many stochastic puff sites promotes the generation of regularly periodic global Ca2+ signals, the properties of individual Ca2+ puffs control the kinetics of Ca2+ spiking and the (higher) frequency of subcellular spikes in their local microdomain.