Defective granule exocytosis in Rab27a-deficient lymphocytes from Ashen mice
Defective granule exocytosis in Rab27a-deficient lymphocytes from Ashen mice
复制标题
DOI：
10.1083/jcb.152.4.835
复制
发表时间：
2001-02-19
影响因子：
7.8
通讯作者：
Henkart, PA
中科院分区：
文献类型：
--
作者：
Haddad, EK;Wu, XF;Henkart, PA
由于Rab27a的突变与人类的免疫缺陷有关，我们研究了含有Rab27a剪接突变的灰色小鼠的细胞毒性淋巴细胞功能。与对照C3H ctl相比，灰白的细胞毒性T淋巴细胞（ctl）对fas阴性靶细胞的裂解活性降低了约90%，灰白的自然杀伤细胞活性也同样降低。尽管它们的颗粒介导的细胞毒性途径存在严重缺陷，但灰色ctl表现出正常的FasL-Fas细胞毒性途径。灰色T细胞的CD4/8表型及其增殖反应与对照组相似。灰色ctl具有正常水平的穿孔素和颗粒酶A和B，以及正常的穿孔素阳性颗粒，当ctl与抗cd3包被珠相互作用时，穿孔素阳性颗粒极化。然而，在灰色小鼠的CD8（+）和CD4(+) T细胞中，抗cd3诱导的快速颗粒分泌明显缺陷。由于T细胞受体刺激的干扰素分泌正常，因此在构成途径中未观察到这种胞吐缺陷。基于这些结果和我们的证明，Rab27a与颗粒酶b阳性颗粒共定位，并且在灰色ctl中检测不到，我们得出结论，Rab27a是颗粒胞外分泌的后期步骤所必需的，与目前Rab27a蛋白在囊泡对接和融合中的功能模型相一致。
Because mutations in Rab27a have been linked to immune defects in humans, we have examined cytotoxic lymphocyte function in ashen mice, which contain a splicing mutation in Rab27a. Ashen cytotoxic T lymphocytes (CTLs) showed a >90% reduction in lytic activity on Fas-negative target cells compared with control C3H CTLs, and ashen natural killer cell activity was likewise diminished. Although their granule-mediated cytotoxicity pathway is profoundly defective, ashen CTLs displayed a normal FasL-Fas cytotoxicity pathway. The CD4/8 phenotype of ashen T cells and their proliferative responses were similar to controls. Ashen CTLs had normal levels of perforin and granzymes A and B and normal-appearing perforin-positive granules, which polarized upon interaction of the CTLs with anti-CD3-coated beads. However, rapid anti-CD3-induced granule secretion was drastically defective in both CD8(+) and CD4(+) T cells from ashen mice. This defect in exocytosis was not observed in the constitutive pathway, as T cell receptor-stimulated interferon-gamma secretion was normal. Based on these results and our demonstration that Rab27a colocalizes with granzyme B-positive granules and is undetectable in ashen CTLs, we conclude that Rab27a is required for a late step in granule exocytosis, compatible with current models of Rab protein function in vesicle docking and fusion.