CAPS acts at a prefusion step in dense-core vesicle exocytosis as a PIP2 binding protein
CAPS acts at a prefusion step in dense-core vesicle exocytosis as a PIP2 binding protein
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DOI：
10.1016/j.neuron.2004.07.028
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发表时间：
2004-08-19
期刊：
影响因子：
16.2
通讯作者：
Martin, TFJ
中科院分区：
文献类型：
--
作者：
Grishanin, RN;Kowalchyk, JA;Martin, TFJ
CAPS-1是Ca 2+触发的致密核心囊泡与质膜融合所必需的，但其作用位点和机制尚不清楚。我们分析了Ca 2+触发的胞吐重组渗透性PC 12细胞的动力学。CAPS-1通过作用于限速的、依赖于Ca 2+的预融合步骤来增加Ca 2+触发的囊泡胞吐的初始速率。CAPS-1活性依赖于先前的ATP依赖性引发，在此期间发生PIP 2合成。CAPS-1活性和与质膜的结合依赖于PIP 2- Call在不存在CAPS-1的情况下触发囊泡融合是无效的，而是促进了由质膜PIP 2减少引起的对CAPS-1的脱敏。我们的结论是，CAPS-1功能后，ATP依赖性引发作为PIP 2结合蛋白，以增强Ca 2+依赖的DCV胞吐。致密核心囊泡胞吐中的基本预融合步骤涉及PIP 2的连续ATP依赖性合成和随后的CAPS-1的PIP 2依赖性作用。PIP 2水平和CAPS-1活性的调节将控制神经肽和单胺能递质的分泌。
CAPS-1 is required for Ca2+-triggered fusion of dense-core vesicles with the plasma membrane, but its site of action and mechanism are unknown. We analyzed the kinetics of Ca2+-triggered exocytosis reconstituted in permeable PC12 cells. CAPS-1 increased the initial rate of Ca2+-triggered vesicle exocytosis by acting at a rate-limiting, Ca2+-dependent prefusion step. CAPS-1 activity depended upon prior ATP-dependent priming during which PIP2 synthesis occurs. CAPS-1 activity and binding to the plasma membrane depended upon PIP2- Call Was ineffective in triggering vesicle fusion in the absence of CAPS-1 but instead promoted desensitization to CAPS-1 resulting from decreased plasma membrane PIP2. We conclude that CAPS-1 functions following ATP-dependent priming as a PIP2 binding protein to enhance Ca2+-dependent DCV exocytosis. Essential prefusion steps in dense-core vesicle exocytosis involve sequential ATP-dependent synthesis of PIP2 and the subsequent PIP2-dependent action of CAPS-1. Regulation of PIP2 levels and CAPS-1 activity would control the secretion of neuropeptides and monoaminergic transmitters.