Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Leicester, United Kingdom.
J Allergy Clin Immunol. 2012 Jun;129(6):1628-35.e2. doi: 10.1016/j.jaci.2012.01.070. Epub 2012 Mar 10.
Influx of extracellular Ca(2+) into human lung mast cells (HLMCs) is essential for the FcεRI-dependent release of preformed granule-derived mediators and newly synthesized autacoids and cytokines. However, the identity of the ion channels underlying this Ca(2+) influx is unknown. The recently discovered members of the CRACM/Orai ion channel family that carries the Ca(2+) release-activated Ca(2+) current are candidates.
To investigate the expression and function of CRACM channels in HLMCs.
CRACM mRNA, protein, and functional expression were examined in purified HLMCs and isolated human bronchus.
CRACM1, -2, and -3 mRNA transcripts and CRACM1 and -2 proteins were detectable in HLMCs. A CRACM-like current was detected following FcεRI-dependent HLMC activation and also in HLMCs dialyzed with 30 μM inositol triphosphate. The Ca(2+)-selective current obtained under both conditions was blocked by 10 μM La(3+) and Gd(3+), known blockers of CRACM channels, and 2 distinct and specific CRACM-channel blockers-GSK-7975A and Synta-66. Both blockers reduced FcεRI-dependent Ca(2+) influx, and 3 μM GSK-7975A and Synta-66 reduced the release of histamine, leukotriene C(4), and cytokines (IL-5/-8/-13 and TNFα) by up to 50%. Synta-66 also inhibited allergen-dependent bronchial smooth muscle contraction in ex vivo tissue.
The presence of CRACM channels, a CRACM-like current, and functional inhibition of HLMC Ca(2+) influx, mediator release, and allergen-induced bronchial smooth muscle contraction by CRACM-channel blockers supports a role for CRACM channels in FcεRI-dependent HLMC secretion. CRACM channels are therefore a potential therapeutic target in the treatment of asthma and related allergic diseases.
细胞外钙离子流入人肺肥大细胞（HLMCs）对于 FcεRI 依赖性的预先形成的颗粒衍生介质和新合成的自分泌和细胞因子的释放是必需的。然而，这种钙离子内流所依赖的离子通道的身份尚不清楚。最近发现的 CRACM/Orai 离子通道家族的成员携带钙释放激活的钙电流，是候选者。
研究 CRACM 通道在 HLMCs 中的表达和功能。
在纯化的 HLMCs 和分离的人支气管中检查 CRACM mRNA、蛋白和功能表达。
CRACM1、-2 和 -3 mRNA 转录本和 CRACM1 和 -2 蛋白在 HLMCs 中可检测到。在 FcεRI 依赖性 HLMC 激活后以及在 HLMCs 用 30 μM 三磷酸肌醇透析后，检测到类似 CRACM 的电流。在这两种情况下获得的钙选择性电流均被 10 μM La(3+) 和 Gd(3+) 阻断，已知的 CRACM 通道阻断剂，以及 2 种不同的和特异的 CRACM 通道阻断剂-GSK-7975A 和 Synta-66。这两种阻断剂均减少 FcεRI 依赖性的 Ca(2+)内流，并且 3 μM GSK-7975A 和 Synta-66 减少组胺、白三烯 C(4)和细胞因子（IL-5/-8/-13 和 TNFα）的释放多达 50%。Synta-66 还抑制了离体组织中过敏原依赖性的支气管平滑肌收缩。
CRACM 通道的存在、类似 CRACM 的电流以及 CRACM 通道阻断剂对 HLMC Ca(2+)内流、介质释放和过敏原诱导的支气管平滑肌收缩的功能抑制支持 CRACM 通道在 FcεRI 依赖性 HLMC 分泌中的作用。因此，CRACM 通道是治疗哮喘和相关过敏性疾病的潜在治疗靶点。
