Calmidazolium and arachidonate activate a calcium entry pathway that is distinct from store-operated calcium influx in HeLa cells
Calmidazolium and arachidonate activate a calcium entry pathway that is distinct from store-operated calcium influx in HeLa cells
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DOI：
10.1042/bj20040097
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发表时间：
2004-08-01
影响因子：
4.1
通讯作者：
Roderick, HL
中科院分区：
文献类型：
--
作者：
Peppiatt, CM;Holmes, AM;Roderick, HL
耗尽细胞内钙库的激动剂也能激活钙内流，尽管钙库释放和钙内流之间的联系机制尚不清楚。一种潜在的机制涉及“存储操作的通道”，它对细胞内钙池的耗尽做出反应。虽然SOCE(存储操作的钙内流)被认为是激素刺激非电兴奋细胞时钙内流的主要途径，但最近的证据表明，由花生四烯酸等代谢物激活的替代途径是生理性钙内流的原因。目前尚不清楚这种信使激活途径是否存在于所有细胞中，它们是否真的有别于SOCE，以及涉及哪些代谢物。在本研究中，我们证明了HeLa细胞表达两种药理和机制上不同的钙离子进入途径。一种是无处不在的SOCE途径，另一种是对花生四烯酸敏感的非SOCE。我们发现，这两种钙离子进入途径都可以提供持久的钙离子升高，但基于它们对2-氨基乙氧基二苯硼酸酯、LOE-908{(R，S)-(3，4-dihydro-6，7-dimethoxy-isochinolin-1-yl)-2-phenyl-N，N-二[2-(2，3，4-三甲氧基苯基)乙基]乙酰胺甲磺酸盐}和Gd的区分敏感性)不同。此外，非SOCE和非SOCE对锶具有渗透性。此外，与SOCE不同的是，非SOCE途径不需要耗尽存储，并且对使用jasplakinolide或离子霉素预处理的质膜前方的内质网移位不敏感。由于花生四烯酸的显性作用，这些途径并不同时传导CAR(2+)，从而迅速抑制SOCE并促进非SOCE的钙内流。虽然外源应用花生四烯酸可以激活非SOCE，但最有效的刺激方法是应用广泛使用的钙调蛋白拮抗剂卡咪唑，因为它有激活磷脂酶A(2)的能力。
Agonists that deplete intracellular Ca2+ stores also activate Ca2+ entry, although the mechanism by which store release and Ca2+ influx are linked is unclear. A potential mechanism involves 'store-operated channels' that respond to depletion of the intracellular Ca2+ pool. Although SOCE (store-operated Ca2+ entry) has been considered to be the principal route for Ca2+ entry during hormonal stimulation of non-electrically excitable cells, recent evidence has suggested that alternative pathways activated by metabolites such as arachidonic acid are responsible for physiological Ca2+ influx. It is not clear whether such messenger-activated pathways exist in all cells, whether they are truly distinct from SOCE and which metabolites are involved. In the present study, we demonstrate that HeLa cells express two pharmacologically and mechanistically distinct Ca2+ entry pathways. One is the ubiquitous SOCE route and the other is an arachidonate-sensitive non-SOCE. We show that both these Ca2+ entry pathways can provide long-lasting Ca2+ elevations, but that the channels are not the same, based on their differential sensitivity to 2-aminoethoxydiphenyl borate, LOE-908 {(R,S)-(3,4-dihydro-6,7-dimethoxy-isochinolin-1-yl)-2-phenyl-N,N-di[2-(2,3,4-trimethoxyphenyl)ethyl]acetamid mesylate} and gadolinium. In addition, non-SOCE and not SOCE was permeable to strontium. Furthermore, unlike SOCE, the non-SOCE pathway did not require store depletion and was not sensitive to displacement of the endoplasmic reticulum front the plasma membrane using jasplakinolide or ionomycin pretreatment. These pathways did not conduct Car(2+) simultaneously due to the dominant effect of arachidonate, which rapidly curtails SOCE and promotes Ca2+ influx via non-SOCE. Although non-SOCE could be activated by exogenous application of arachidonate, the most robust method for stimulation of this pathway was application of the widely used calmodulin antagonist calmidazolium, due to its ability to activate phospholipase A(2).