Mechanism of extracellular ATP-induced inhibition of store-operated Ca^<2+> entry

细胞外 ATP 诱导的钙池操纵的 Ca^2 内流抑制机制

• 批准号: 12670038
• 负责人: OMATSU Mariko
• 金额: $ 2.5万
• 依托单位: Shiga University of Medical Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12670038/
• 关键词: ATP; P2 receptor; intracellular Ca^<2+>; store-operated Ca^<2+> entry; G-protein coupled receptor; cytoskeleton; actin; brown adipocyte; 小胞体

Agonist-induced activation of phospholipase C/Gq produces IP_3 which opens the Ca^<2+> channels in ER in most of the cells. The emptying or even decrease of Ca^<2+> stores triggers the store-operated Ca^<2+> entry across the plasma membrane, which has been recognized to be the major Ca^<2+> influx in non-electric excitable cells. We have reported that the extracellular ATP completely Inhibits the thapsigargin-induced store-operated Ca^<2+> entry in rat primary cultured brown adipocytes. In this project, we investigated the mechanism of the ATP-induced inhibition of the store-operated Ca^<2+> entry and obtained the following results.1. Extracellular ATP inhibited the store-operated Ca^<2+> entry in the absence of extracellular Mg^<2+> suggesting that the activation of ect-enzymes does not play a role.2. P2 receptor antagonists suramin. and PPADS suppressed the thapsigargin-induced Ca^<2+> influx as well as the inhibition of the transient Ca^<2+> elevation.3. Extracellular ATP stimulated the redistribution of actin filaments in peripheral region of the cell (near the plasma membrane).4. Extracellular ATP enhanced peripheral polymerization of actin in thapsigargin-pretreated cells5. P2 receptor antagonists inhibited the ATP-lnduced peripheral actin polymerization6. Actin polymerization inhibitor cytochalasin D blocked the effect of ATP, and furthermore, extracellular ATP did not inhibit store-operated Ca^<2+> entry in cytochalasin D-pretreated cells.These observations suggest that extracellular ATP stimulates the formation of the cortical actin layer mediated through P2 receptors, resulting in blocking the influx of Ca^<2+> in rat brown adipocytes.

在大多数细胞中，激动剂诱导的磷脂酶C/Gq激活产生IP_3，打开内质网中的Ca^<2+>通道。Ca^<2+>储存器的排空甚至减少触发储存器操作的Ca^<2+>穿过质膜进入，这被认为是Ca^<2+>在非电可兴奋细胞中的主要内流。我们已经报道了细胞外ATP完全抑制thapsigargin诱导的储存操作的Ca^<2+>进入大鼠原代培养的棕色脂肪细胞。在这个项目中，我们研究了atp诱导的抑制储存操作的Ca^<2+>入口的机制，得到了以下结果。在没有细胞外Mg^<2+>的情况下，细胞外ATP抑制了储存操作的Ca^<2+>的进入，这表明ect-酶的激活不起作用。P2受体拮抗剂苏拉明。PPADS抑制了thapsigargin诱导的Ca^<2+>内流，并抑制了Ca^<2+>的瞬时升高。细胞外ATP刺激肌动蛋白丝在细胞外周区域（靠近质膜）的重新分配。细胞外ATP增强了thapsigarin预处理细胞中肌动蛋白的外周聚合5。P2受体拮抗剂抑制atp诱导的外周肌动蛋白聚合6。肌动蛋白聚合抑制剂细胞松弛素D阻断ATP的作用，此外，细胞外ATP不抑制储存操作的Ca^<2+>进入细胞松弛素D预处理的细胞。这些观察结果表明，细胞外ATP通过P2受体介导刺激皮层肌动蛋白层的形成，从而阻断Ca^<2+>在大鼠棕色脂肪细胞中的内流。

项目成果

Matuura H. et al.: "Rapidly and slowly activating components of delayed rectifier K^<+> current in guinea-pig sino-atrial node pacemaker cells"Journal of Physiology. (in press). (2002)

Matuura H.等人：“豚鼠窦房结起搏细胞中延迟整流器K^<>电流的快速和缓慢激活成分”生理学杂志。

Matsuura, H. et al.: "Rapidly and slowly activating components of delayed rectifier K^+ current in guinea-pig sino-atrial node pacemaker cells"Journal of Physiology. (in press). (2002)

Matsuura，H.等人：“豚鼠窦房结起搏细胞中延迟整流器K 电流的快速和缓慢激活成分”生理学杂志。

Sanada H. et al.: "Increase in intracellular Ca^<2+> and calcitomin gene-related peptide release through metabotropic P2Y receptor in rat dorsal root ganglion neurons"Neuroscience. (in press). (2002)

Sanada H.等人：“通过大鼠背根神经节神经元中的代谢型P2Y受体增加细胞内Ca 2+ 和降钙素基因相关肽的释放”神经科学。

Sanada, H. et al.: "Increase in intracellular Ca^<2+> and calcitonin gene-related peptide release through metabotropic P2Y receptor in rat dorsal root ganglion neurons"Neuroscience. (in press). (2002)

Sanada，H.等人：“通过大鼠背根神经节神经元中代谢型P2Y受体增加细胞内Ca 2+ 和降钙素基因相关肽的释放”神经科学。