Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA.
J Immunol. 2010 Nov 15;185(10):5845-58. doi: 10.4049/jimmunol.1001796. Epub 2010 Oct 18.
ORAI1 is the pore-forming subunit of the Ca(2+) release-activated Ca(2+) (CRAC) channel, which is responsible for store-operated Ca(2+) entry in lymphocytes. A role for ORAI1 in T cell function in vivo has been inferred from in vitro studies of T cells from human immunodeficient patients with mutations in ORAI1 and Orai1(-/-) mice, but a detailed analysis of T cell-mediated immune responses in vivo in mice lacking functional ORAI1 has been missing. We therefore generated Orai1 knock-in mice (Orai1(KI/KI)) expressing a nonfunctional ORAI1-R93W protein. Homozygosity for the equivalent ORAI1-R91W mutation abolishes CRAC channel function in human T cells resulting in severe immunodeficiency. Homozygous Orai1(KI/KI) mice die neonatally, but Orai1(KI/KI) fetal liver chimeric mice are viable and show normal lymphocyte development. T and B cells from Orai1(KI/KI) mice display severely impaired store-operated Ca(2+) entry and CRAC channel function resulting in a strongly reduced expression of several key cytokines including IL-2, IL-4, IL-17, IFN-γ, and TNF-α in CD4(+) and CD8(+) T cells. Cell-mediated immune responses in vivo that depend on Th1, Th2, and Th17 cell function were severely attenuated in ORAI1-deficient mice. Orai1(KI/KI) mice lacked detectable contact hypersensitivity responses and tolerated skin allografts significantly longer than wild-type mice. In addition, T cells from Orai1(KI/KI) mice failed to induce colitis in an adoptive transfer model of inflammatory bowel disease. These findings reaffirm the critical role of ORAI1 for T cell function and provide important insights into the in vivo functions of CRAC channels for T cell-mediated immunity.
ORAI1 是 Ca(2+) 释放激活的 Ca(2+)（CRAC）通道的形成孔亚基，负责淋巴细胞中的储存操纵的 Ca(2+) 内流。在人类免疫缺陷患者的 T 细胞体外研究中，已经推断出 ORAI1 在 T 细胞功能中的作用，这些患者存在 ORAI1 和 Orai1(-/-) 小鼠中的突变，但是在缺乏功能性 ORAI1 的小鼠体内对 T 细胞介导的免疫反应进行详细分析一直缺失。因此，我们生成了表达非功能性 ORAI1-R93W 蛋白的 Orai1 敲入小鼠（Orai1(KI/KI)）。该突变导致人类 T 细胞中的 CRAC 通道功能丧失，从而导致严重的免疫缺陷。纯合的 ORAI1-R91W 突变导致 Orai1(KI/KI) 小鼠在新生时死亡，但 Orai1(KI/KI) 胎肝嵌合小鼠具有活力并且表现出正常的淋巴细胞发育。来自 Orai1(KI/KI) 小鼠的 T 和 B 细胞显示出严重受损的储存操纵的 Ca(2+) 内流和 CRAC 通道功能，导致包括 IL-2、IL-4、IL-17、IFN-γ 和 TNF-α 在内的几种关键细胞因子在 CD4(+) 和 CD8(+) T 细胞中的表达显著降低。依赖于 Th1、Th2 和 Th17 细胞功能的体内细胞介导免疫反应在 ORAI1 缺陷小鼠中严重减弱。ORAI1 缺失小鼠缺乏可检测的接触超敏反应应答，并且比野生型小鼠显著更长时间耐受皮肤同种异体移植物。此外，来自 Orai1(KI/KI) 小鼠的 T 细胞未能在炎症性肠病的过继转移模型中诱导结肠炎。这些发现再次证实了 ORAI1 对 T 细胞功能的关键作用，并为 CRAC 通道在 T 细胞介导的免疫中的体内功能提供了重要的见解。
