Role of 1,4,5-inositol triphosphate-induced Ca2+ release in pollen tube orientation
Role of 1,4,5-inositol triphosphate-induced Ca2+ release in pollen tube orientation
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DOI：
10.1007/s004970050145
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发表时间：
1998-10
影响因子：
--
通讯作者：
R. Malhó
中科院分区：
文献类型：
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作者：
R. Malhó
花粉管定向是一个动态的细胞事件，对成功受精至关重要。以前，它表明，重新定向之前的细胞质游离钙（[Ca 2 +]c）的不对称增加的顶点的细胞将弯曲的一侧。为了寻找这一信号转导途径的靶点，分析了1，4，5-三磷酸肌醇[Ins（1，4，5）P3]在重取向过程中的作用。用离子共聚焦显微镜观察了Ins（1，4，5）P3在不同细胞区域的局部光激活作用及其对[Ca ~（2+）] c的影响。结果表明，Ins（1，4，5）P3在细胞核或根尖下的光解导致细胞内[Ca ~（2+）] c的瞬时增加和生长轴的重新定向，而在根尖的光解则常常导致生长紊乱或根尖爆裂。在光活化前用Ins（1，4，5）P3受体阻断剂肝素灌注细胞可抑制[Ca ~（2+）] c的增加，且未观察到细胞重定向。Ca 2+释放从铟（1，4，5）P3-依赖存储本地化的柄管，因此似乎是信号转导途径的一部分，控制管的指导，虽然不是主要的刺激，导致重新定位。
Pollen tube reorientation is a dynamic cellular event crucial for successful fertilization. Previously, it was shown that reorientation is preceded by an asymmetric increase of cytosolic free calcium ([Ca2+]c) in the side of the apex to which the cell will bend. In order to find the targets for this signal transduction pathway, the effects of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in the reorientation process were analyzed. Ins(1,4,5)P3was artificially increased in different cell domains by localized photoactivation of caged Ins(1,4,5)P3and its effects on [Ca2+]cmonitored by ion confocal microscopy. It was found that photolysis of caged Ins(1,4,5)P3in the nuclear or subapical region resulted in a transient increase in [Ca2+]cand reorientation of the growth axis, while photolysis in the apex frequently resulted in disturbed growth or tip bursting. Perfusion of the cells with the Ins(1,4,5)P3receptor blocker heparin prior to photoactivation inhibited the increase in [Ca2+]cand no reorientation was observed. Ca2+release from Ins(1,4,5)P3-dependent stores localized in the shank of the tube thus seems to be part of the signal transduction pathway that controls tube guidance, although not the primary stimulus leading to reorientation.