Program in Molecular Pathogenesis, Helen L. and Martin S. Kimmel Center for Biology and Medicine of the Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA.
Eur J Immunol. 2013 Dec;43(12):3343-54. doi: 10.1002/eji.201243255. Epub 2013 Sep 6.
Entry of lymphocytes into secondary lymphoid organs (SLOs) involves intravascular arrest and intracellular calcium ion ([Ca(2+)]i) elevation. TCR activation triggers increased [Ca(2+)]i and can arrest T-cell motility in vitro. However, the requirement for [Ca(2+)]i elevation in arresting T cells in vivo has not been tested. Here, we have manipulated the Ca(2+) release-activated Ca(2+) (CRAC) channel pathway required for [Ca(2+)]i elevation in T cells through genetic deletion of stromal interaction molecule (STIM) 1 or by expression of a dominant-negative ORAI1 channel subunit (ORAI1-DN). Interestingly, the absence of CRAC did not interfere with homing of naïve CD4(+) T cells to SLOs and only moderately reduced crawling speeds in vivo. T cells expressing ORAI1-DN lacked TCR activation induced [Ca(2+)]i elevation, yet arrested motility similar to control T cells in vitro. In contrast, antigen-specific ORAI1-DN T cells had a twofold delayed onset of arrest following injection of OVA peptide in vivo. CRAC channel function is not required for homing to SLOs, but enhances spatiotemporal coordination of TCR signaling and motility arrest.
淋巴细胞进入次级淋巴器官（SLO）涉及血管内捕获和细胞内钙离子（[Ca(2+)]i）升高。TCR 激活触发[Ca(2+)]i 的增加，并可在体外阻止 T 细胞的迁移。然而，尚未检测到体内阻止 T 细胞所需的[Ca(2+)]i 升高。在这里，我们通过遗传缺失基质相互作用分子（STIM）1 或表达显性负 ORAI1 通道亚基（ORAI1-DN）来操纵 T 细胞中升高[Ca(2+)]i 所需的 Ca(2+)释放激活的 Ca(2+)（CRAC）通道途径。有趣的是，CRAC 的缺失并不干扰幼稚 CD4(+)T 细胞归巢到 SLO，并且仅适度降低体内的爬行速度。表达 ORAI1-DN 的 T 细胞缺乏 TCR 激活诱导的[Ca(2+)]i 升高，但在体外与对照 T 细胞一样阻止了迁移。相比之下，抗原特异性 ORAI1-DN T 细胞在体内注射 OVA 肽后，其捕获的起始时间延迟了两倍。CRAC 通道功能对于归巢到 SLO 不是必需的，但增强了 TCR 信号和迁移捕获的时空协调。
