Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry
Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry
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DOI：
10.1074/jbc.m011571200
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发表时间：
2001-05-11
影响因子：
4.8
通讯作者：
Putney, JW
中科院分区：
文献类型：
--
作者：
Broad, LM;Braun, FJ;Putney, JW
我们研究了在泪腺泡细胞、大鼠嗜碱性白血病细胞和DT 40 B淋巴细胞中，磷脂酶C、多磷酸肌醇和1，4，5-三磷酸肌醇（IP 3）在容量性钙内流和钙释放激活的钙电流（I-crac）中的假定作用，用U 73122抑制磷脂酶C可阻断钙内流和I-crac激活，无论是对磷脂酶C-偶联激动剂或与毒胡萝卜素的钙库耗竭。阻断磷脂酰肌醇4-激酶的渥曼青霉素浓度降低细胞聚磷酸肌醇的浓度，完全阻断钙离子进入和I-crac。的膜渗透性IP 3受体抑制剂，2-氨基乙氧基二苯基硼烷，阻断了电容性钙离子进入和I-crac。然而，很可能2-氨基乙氧基二苯基硼烷不通过对IP 3受体的作用来抑制，因为该药物在野生型DT 40 B细胞和所有三种IP 3受体的基因都被破坏的DT 40 B细胞中同样有效。细胞内应用另一种有效的IP 3受体拮抗剂肝素，未能抑制I-crac的激活。最后，抑制I-crac激活U 73122或渥曼青霉素没有逆转或阻止直接细胞内应用的IP 3。这些研究结果表明，需要磷脂酶C和聚磷酸肌醇激活的电容性钙进入。然而，这些结果对先前提出的IP 3和IP 3受体在这种机制中的作用提出了质疑，至少在这些特定的细胞类型中。
We investigated the putative roles of phospholipase C, polyphosphoinositides, and inositol 1,4,5-trisphosphate (IP3) in capacitative calcium entry and calcium release-activated calcium current (I-crac) in lacrimal acinar cells, rat basophilic leukemia cells, and DT40 B-lymphocytes, Inhibition of phospholipase C with U73122 blocked calcium entry and I-crac activation whether in response to a phospholipase C-coupled agonist or to calcium store depletion with thapsigargin. Run-down of cellular polyphosphoinositides by concentrations of wortmannin that block phosphatidylinositol 4-kinase completely blocked calcium entry and I-crac. The membrane-permeant IP3 receptor inhibitor, 2-aminoethoxydiphenyl borane, blocked both capacitative calcium entry and I-crac. However, it is likely that 2-aminoethoxydipheny1 borane does not inhibit through an action on the IP3 receptor because the drug was equally effective in wild-type DT40 B-cells and in DT40 B-cells whose genes for all three IP3 receptors had been disrupted. Intracellular application of another potent IP3 receptor antagonist, heparin, failed to inhibit activation of I-crac. Finally, the inhibition of I-crac activation by U73122 or wortmannin was not reversed or prevented by direct intracellular application of IP3. These findings indicate a requirement for phospholipase C and for polyphosphoinositides for activation of capacitative calcium entry. However, the results call into question the previously suggested roles of IP3 and IP3 receptor in this mechanism, at least in these particular cell types.