CAPACITATIVE CA2+ ENTRY REGULATES CA2+-SENSITIVE ADENYLYL CYCLASES
CAPACITATIVE CA2+ ENTRY REGULATES CA2+-SENSITIVE ADENYLYL CYCLASES
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DOI：
10.1042/bj2970437
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发表时间：
1994-02-01
影响因子：
4.1
通讯作者：
MAHEY, R
中科院分区：
文献类型：
--
作者：
COOPER, DMF;YOSHIMURA, M;MAHEY, R
目前描述的腺苷酸环化酶种类的数量可以通过在体外测定中在亚微摩尔浓度范围内的Ca 2+来调节。这些观察结果的调节意义取决于细胞内Ca2+的生理性升高是否可以调节完整细胞中这些环化酶的活性。然而，实现胞质Ca 2+的生理升高是复杂的，因为胞质Ca 2+的激素增加可能伴随着额外的作用，例如G蛋白的β γ亚基的释放和蛋白激酶C的激活，这可能对环化酶活性具有不同的类型特异性作用。因此，我们设计了一种策略的基础上容量的Ca 2+进入显示，当I型和VI型腺苷酸环化酶在人胚肾293细胞中表达，它们分别被刺激和抑制Ca 2+进入。La 3+离子阻断Ca 2+内流阻断了Ca 2+内流对cAMP合成的影响。这些研究证实，腺苷酸环化酶被认为是敏感的钙在体外试验中可以调节生理Ca2+进入，因此，这样的环化酶准备响应细胞内Ca2+的变化，在组织中，它们被表达。
A number of the currently described adenylyl cyclase species can be regulated by Ca2+ in the submicromolar concentration range in in vitro assays. The regulatory significance of these observations hinges on whether a physiological elevation in intracellular Ca2+ can regulate these cyclase activities in intact cells. However, achieving a physiological elevation in cytosolic Ca2+ is complicated by the fact that hormonal increases in cytosolic Ca2+ can be accompanied by additional effects, such as liberation of beta gamma-subunits of G-proteins and activation of protein kinase C, which can have disparate type-specific effects on cyclase activities. Therefore we have devised a strategy based on capacitative Ca2+ entry to show that, when types I and VI adenylyl cyclase are expressed in human embryonic kidney 293 cells, they are stimulated and inhibited respectively by Ca2+ entry. Blockade of Ca2+ entry by La3+ ions blocks the effects of Ca2+ entry on cyclic AMP synthesis. These studies establish that adenylyl cyclases deemed to be sensitive to Ca2+ in in vitro assays can be regulated by physiological Ca2+ entry, and therefore, such cyclases are poised to respond to changes in intracellular Ca2+ in tissues in which they are expressed.