Different Munc13 Isoforms Function as Priming Factors in Lytic Granule Release from Murine Cytotoxic T Lymphocytes
Different Munc13 Isoforms Function as Priming Factors in Lytic Granule Release from Murine Cytotoxic T Lymphocytes
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DOI：
10.1111/tra.12074
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发表时间：
2013-07-01
期刊：
影响因子：
4.5
通讯作者：
Rettig, Jens
中科院分区：
文献类型：
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作者：
Dudenhoeffer-Pfeifer, Monika;Schirra, Claudia;Rettig, Jens
为了将溶解颗粒(LGs)与免疫突触的质膜融合，细胞毒性T淋巴细胞(CTL)必须通过启动过程使这些LGs具有融合能力。在脑和神经内分泌腺等分泌组织中，这一过程是由Munc13蛋白家族的成员介导的。在人类CTL中，Munc13-4基因的突变导致杀伤效率的严重丧失，导致家族性噬血细胞淋巴组织细胞增生症3型，这表明Munc13的其他亚型在免疫系统中具有类似的作用。在这里，我们研究了不同的Munc13亚型在小鼠CTL的启动过程中在mRNA和蛋白质水平上的作用。我们证明Munc13-1和Munc13-4是小鼠CTL中仅有的Munc13亚型。这两种亚型都挽救了Munc13-4缺陷的Jinx小鼠来源的CTL的严重分泌缺陷。全内反射荧光显微镜的迁移率研究表明，Munc13-4和Munc13-1负责LGs的启动过程。此外，还可以确定负责功能融合的Munc13蛋白的结构域。从这些数据我们得出结论，Munc13家族的两个亚型，Munc13-1和Munc13-4，在小鼠CTL中在功能上是多余的。
In order to fuse lytic granules (LGs) with the plasma membrane at the immunological synapse, cytotoxic T lymphocytes (CTLs) have to render these LGs fusion-competent through the priming process. In secretory tissues such as brain and neuroendocrine glands, this process is mediated by members of the Munc13 protein family. In human CTLs, mutations in the Munc13-4 gene cause a severe loss in killing efficiency, resulting in familial hemophagocytic lymphohistiocytosis type 3, suggesting a similar role of other Munc13 isoforms in the immune system. Here, we investigate the contribution of different Munc13 isoforms to the priming process of murine CTLs at both the mRNA and protein level. We demonstrate that Munc13-1 and Munc13-4 are the only Munc13 isoforms present in mouse CTLs. Both isoforms rescue the drastical secretion defect of CTLs derived from Munc13-4-deficient Jinx mice. Mobility studies using total internal reflection fluorescence microscopy indicate that Munc13-4 and Munc13-1 are responsible for the priming process of LGs. Furthermore, the domains of the Munc13 protein, which is responsible for functional fusion, could be identified. We conclude from these data that both isoforms of the Munc13 family, Munc13-1 and Munc13-4, are functionally redundant in murine CTLs.