Spatiotemporal patterning of IP3-mediated Ca2+ signals in Xenopus oocytes by Ca2+-binding proteins
Spatiotemporal patterning of IP3-mediated Ca2+ signals in Xenopus oocytes by Ca2+-binding proteins
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DOI：
10.1113/jphysiol.2003.059204
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发表时间：
2004-04-15
影响因子：
5.5
通讯作者：
Parker, I
中科院分区：
文献类型：
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作者：
Dargan, SL;Schwaller, B;Parker, I
Ca2+结合蛋白（CaBPs）在许多不同的细胞类型中以高度特异性的方式表达，但其选择性分布模式的生理基础尚不清楚。我们利用共聚焦线扫描显微镜和光子释放法研究了移动胞质CaBPs对光子诱导的Ca2+信号时空特性的影响。细小白蛋白（PV）是一种具有缓慢Ca2+结合动力学的CaBP，缩短了ip3诱发的Ca2+信号的持续时间，并将全局反应“巴尔干化”为离散的局部事件（泡）。相比之下，calretinin (CR)，一种被认为是快速缓冲剂，在高[IP3]负载CR或PV的卵母细胞中，延长了Ca2+反应，并促进了空间均匀Ca2+信号的“全球化”，在对照组中，在光解闪光后，显示出Ca2+泡芙，这些局部事件的时空特性受到PV和CR的差异调节。PV非常接近慢速缓冲EGTA的作用，而CR与快速缓冲BAPTA表现出重要的差异。最值得注意的是，在加载BAPTA后从未观察到气泡，并且这种外源性缓冲液没有显示出与CR明显的IP3作用的显着敏化。Ca2+缓冲液和具有不同动力学的cabp微调全局和局部细胞内Ca2+信号的能力可能具有重要的生理意义。
Ca2+-binding proteins (CaBPs) are expressed in a highly specific manner across many different cell types, yet the physiological basis underlying their selective distribution patterns remains unclear. We used confocal line-scan microscopy together with photo-release of IP3 in Xenopus oocytes to investigate the actions of mobile cytosolic CaBPs on the spatiotemporal properties of IP3-evoked Ca2+ signals. Parvalbumin (PV), a CaBP with slow Ca2+-binding kinetics, shortened the duration of IP3-evoked Ca2+ signals and 'balkanized' global responses into discrete localized events (puffs). In contrast, calretinin (CR), a presumed fast buffer, prolonged Ca2+ responses and promoted 'globalization' of spatially uniform Ca2+ signals at high [IP3] Oocytes loaded with CR or PV showed Ca2+ puffs following photolysis flashes that were subthreshold in controls, and the spatiotemporal properties of these localized events were differentially modulated by PV and CR. In comparison to results we previously obtained with exogenous Ca2+ buffers, PV closely mimicked the actions of the slow buffer EGTA, whereas CR showed important differences from the fast buffer BAPTA. Most notably, puffs were never observed after loading BAPTA, and this exogenous buffer did not show the marked sensitization of IP3 action evident with CR. The ability of Ca2+ buffers and CaBPs with differing kinetics to fine-tune both global and local intracellular Ca2+ signals is likely to have significant physiological implications.