Design of a potent and selective inhibitor of the intermediate-conductance Ca2+-activated K+ channel, IKCa1:: A potential immunosuppressant
Design of a potent and selective inhibitor of the intermediate-conductance Ca2+-activated K+ channel, IKCa1:: A potential immunosuppressant
复制标题
DOI：
10.1073/pnas.97.14.8151
复制
发表时间：
2000-07-05
影响因子：
11.1
通讯作者：
Chandy, KG
中科院分区：
文献类型：
--
作者：
Wulff, H;Miller, MJ;Chandy, KG
抗真菌药克霉唑是一种有效的中电导钙激活K+通道（IKCa 1）抑制剂，目前正在进行治疗镰状细胞病和腹泻的临床试验，可有效改善类风湿性关节炎的症状。然而，克霉唑对细胞色素P450酶的抑制限制了其治疗价值。我们已经使用了一个合理的设计策略，开发克霉唑类似物，选择性抑制IKCa 1，而不阻断细胞色素P450酶。83个三芳基甲烷的筛选揭示了通道阻断的药效团不同于细胞色素P450抑制所需的药效团。“IKCa 1-药效团”由被未取代的极性富π电子杂环（吡唑或四唑）或-C=N基团取代的（2-卤代苯基）二苯基甲烷部分组成，而细胞色素P450抑制绝对需要咪唑环。一系列的吡唑，乙腈，和四唑的合成，并发现选择性地阻止IKCa 1。TRAM-34（1-[（2-氯苯基）二苯基甲基]-1H-吡唑）抑制人T淋巴细胞中克隆的和天然的IKCa 1通道，Kd为20-25 nM，选择性是其他离子通道的200- 1，500倍。使用TRAM-34，我们表明，在没有P450抑制的情况下，阻断人淋巴细胞中的IKCa 1，导致抑制有丝分裂原刺激的[H-3]胸苷掺入预活化淋巴细胞的EC 50值为100 nM-1 μ M，取决于供体。TRAM-34和环孢菌素A的组合在抑制淋巴细胞有丝分裂发生方面比任一单独的化合物更有效。我们的研究表明，TRAM-34和相关化合物可能具有作为免疫抑制剂的治疗前景。
The antimycotic clotrimazole, a potent inhibitor of the intermediate-conductance calcium-activated K+ channel, IKCa1, is in clinical trials for the treatment of sickle cell disease and diarrhea and is effective in ameliorating the symptoms of rheumatoid arthritis. However, inhibition of cytochrome P450 enzymes by clotrimazole limits its therapeutic value. We have used a rational design strategy to develop a clotrimazole analog that selectively inhibits IKCa1 without blocking cytochrome P450 enzymes. A screen of 83 triarylmethanes revealed the pharmacophore for channel block to be different from that required for cytochrome P450 inhibition. The "IKCa1-pharmacophore" consists of a (2-halogenophenyl)diphenylmethane moiety substituted by an unsubstituted polar pi-electron-rich heterocycle (pyrazole or tetrazole) or a -C=N group, whereas cytochrome P450 inhibition absolutely requires the imidazole ring. A series of pyrazoles, acetonitriles, and tetrazoles were synthesized and found to selectively block IKCa1. TRAM-34 (1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole) inhibits the cloned and the native IKCa1 channel in human T lymphocytes with a K-d of 20-25 nM and is 200- to 1,500-fold selective over other ion channels. Using TRAM-34, we show that blocking IKCa1 in human lymphocytes, in the absence of P450-inhibition, results in suppression of mitogen-stimulated [H-3]thymidine incorporation of preactivated lymphocytes with EC50-values of 100 nM-1 mu M depending on the donor. Combinations of TRAM-34 and cyclosporin A are more effective in suppressing lymphocyte mitogenesis than either compound alone. Our studies suggest that TRAM-34 and related compounds may hold therapeutic promise as immunosuppressants.