Regulation of Ca2+-release-activated Ca2+ current (Icrac) by ryanodine receptors in inositol 1,4,5-trisphosphate-receptor-deficient DT40 cells.
Regulation of Ca2+-release-activated Ca2+ current (Icrac) by ryanodine receptors in inositol 1,4,5-trisphosphate-receptor-deficient DT40 cells.
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DOI：
10.1042/bj3600017
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发表时间：
2001-11
期刊：
影响因子：
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通讯作者：
K. Kiselyov;Dong Min Shin;N. Shcheynikov;Tomohiro Kurosaki;S. Muallem
中科院分区：
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作者：
K. Kiselyov;Dong Min Shin;N. Shcheynikov;Tomohiro Kurosaki;S. Muallem
肌醇1,4,5-三磷酸（IP(3)）受体（IP(3)R）缺陷的DT40细胞(DT40（IP(3)R-/-）中容性Ca（2+）内流的持续存在提出了一个问题，即通过与Ca（2+）释放通道的构象偶联，门控Ca（2+）释放激活Ca（2+）电流（I(crac)）是否是这些通道门控的一般机制。在本工作中，我们研究了I(crac) Ca（2+）电流在野生型和DT40（IP(3)R-/-）细胞中的激活特性和机制。在这两种类型的细胞中，通过输注EGTA被动消耗内部Ca（2+）储存激活了具有相似特征和时间过程的Ca（2+）电流。电流具有高度的Ca（2+）选择性，并表现出强烈的内向整流，均为典型的I（裂纹）。ryanodine受体（RyR）的激活剂cadp -核糖（cADPR）促进了I（crac）的激活，而RyRs的抑制剂8-N-cADPR、ryanodine和钌红都抑制了DT40（IP(3)R-/-）细胞中I（crac）的激活，即使在离子霉素完全耗尽细胞内Ca（2+）储存后也是如此。野生型和DT40（IP(3)R-/-）细胞表达RyR亚型1和3。与野生型细胞相比，DT40（IP(3)R-/-）细胞中的RyR水平适应于较低的RyR3/RyR1比率。这些结果表明，IP(3)Rs和RyRs可以在DT40细胞中有效地门控I（裂缝），并解释了在没有IP(3)Rs的情况下，内部存储持续门控I（裂缝）的原因。
Persistence of capacitative Ca(2+) influx in inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-deficient DT40 cells (DT40(IP(3)R-/-)) raises the question of whether gating of Ca(2+)-release activated Ca(2+) current (I(crac)) by conformational coupling to Ca(2+)-release channels is a general mechanism of gating of these channels. In the present work we examined the properties and mechanism of activation of I(crac) Ca(2+) current in wild-type and DT40(IP(3)R-/-) cells. In both cell types passive depletion of internal Ca(2+) stores by infusion of EGTA activated a Ca(2+) current with similar characteristics and time course. The current was highly Ca(2+)-selective and showed strong inward rectification, all typical of I(crac). The activator of ryanodine receptor (RyR), cADP-ribose (cADPR), facilitated activation of I(crac), and the inhibitors of the RyRs, 8-N-cADPR, ryanodine and Ruthenium Red, all inhibited I(crac) activation in DT40(IP(3)R-/-) cells, even after complete depletion of intracellular Ca(2+) stores by ionomycin. Wild-type and DT40(IP(3)R-/-) cells express RyR isoforms 1 and 3. RyR levels were adapted in DT40(IP(3)R-/-) cells to a lower RyR3/RyR1 ratio than in wild-type cells. These results suggest that IP(3)Rs and RyRs can efficiently gate I(crac) in DT40 cells and explain the persistence of I(crac) gating by internal stores in the absence of IP(3)Rs.