Pharmacological sensitivity of ATP release triggered by photoliberation of inositol-1,4,5-trisphosphate and zero extracellular calcium in brain endothelial cells
Pharmacological sensitivity of ATP release triggered by photoliberation of inositol-1,4,5-trisphosphate and zero extracellular calcium in brain endothelial cells
复制标题
DOI：
10.1002/jcp.10365
复制
发表时间：
2003-11-01
影响因子：
5.6
通讯作者：
Leybaert, L
中科院分区：
文献类型：
--
作者：
Braet, K;Aspeslagh, S;Leybaert, L
近年来，ATP作为细胞外信使参与细胞间钙信号的传递，引起了人们的广泛兴趣。然而，ATP释放的机制仍然是一个有争议的问题。在本研究中，我们研究了连接蛋白半通道或离子通道在大鼠脑内皮细胞系GP 8释放ATP中的可能贡献。ATP的释放由InsP（3）的光活化或细胞外钙浓度的降低触发。两种触发方案均诱导ATP释放显著高于基线。InsP（3）触发的ATP释放被α-甘草次酸（α-GA）、连接蛋白模拟肽gap 26和27以及三价离子钆和镧完全阻断。除了这些物质外，由零钙触发的ATP释放也被氟灭酸（FFA）、尼氟灭酸和NPPB阻断。间隙27选择性地阻断零钙触发的ATP释放连接蛋白-43转染的HeLa细胞，而在野生型和连接蛋白-32转染的细胞没有效果。在所使用的所有试剂中，仅α-GA、FFA和NPPB显著降低间隙连接偶联。总之，InsP（3）和零钙触发的ATP释放显示出主要的相似性，但在它们对所用药物的敏感性方面也存在一些差异。这表明，这两种刺激触发ATP释放通过相同的机制，这是连接蛋白依赖性的，在两个方向上可渗透的，有力地阻断连接蛋白模拟肽，并与连接蛋白半通道的开放一致。(C)2003 Wiley-Liss，Inc.
Recently, ATP has gained much interest as an extracellular messenger involved in the communication of calcium signals between cells. The mechanism of ATP release is, however, still a matter of debate. In the present study we investigated the possible contribution of connexin hemichannels or ion channels in the release of ATP in GP8, a rat brain endothelial cell line. Release of ATP was triggered by photoactivation of InsP(3) or by reducing the extracellular calcium concentration. Both trigger protocols induced ATP release significantly above baseline. InsP(3)-triggered ATP release was completely blocked by alpha-glycyrrhetinic acid (alpha-GA), the connexin mimetic peptides gap 26 and 27, and the trivalent ions gadolinium and lanthanum. ATP release triggered by zero calcium was, in addition to these substances, also blocked by flufenamic acid (FFA), niflumic acid, and NPPB. Gap 27 selectively blocked zero calcium-triggered ATP release in connexin-43 transfected HeLa cells, while having no effect in wild-type and connexin-32 transfected cells. Of all the agents used, only alpha-GA, FFA and NPPB significantly reduced gap junctional coupling. In conclusion, InsP(3) and zero calcium-triggered ATP release show major similarities but also some differences in their sensitivity to the agents applied. It is suggested that both stimuli trigger ATP release through the same mechanism, which is connexin-dependent, permeable in both directions, potently blocked by connexin mimetic peptides, and consistent with the opening of connexin hemichannels. (C) 2003 Wiley-Liss, Inc.