The tetraspanin CD63 is involved in granule targeting of neutrophil elastase
The tetraspanin CD63 is involved in granule targeting of neutrophil elastase
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DOI：
10.1182/blood-2007-10-116285
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发表时间：
2008-10-15
期刊：
影响因子：
20.3
通讯作者：
Olsson, Inge
中科院分区：
文献类型：
--
作者：
Kallquist, Linda;Hansson, Markus;Olsson, Inge
中性粒细胞弹性蛋白酶（NE）和储存在髓过氧化物酶（MPO）阳性分泌溶酶体/中性粒细胞初级颗粒中的其他管腔蛋白的靶向机制尚不清楚。这些颗粒含有一个完整的膜蛋白，CD 63，与衔接蛋白-3依赖性颗粒输送系统。因此，我们假设CD 63在NE前体（proNE）的颗粒递送中起协同作用。支持这一假设，在COS细胞中共表达后，CD 63和proNE之间的关联被证明。这也涉及proNE的增强的细胞保留，需要完整的大的CD 63细胞外环。此外，在早幼粒细胞HL-60细胞中用RNA干扰或CD 63突变体耗尽CD 63引起细胞NE减少。然而，在CD 63缺失的克隆中，proNE稳态水平与野生型相似，这使得研究CD 63对NE运输的可能影响是可行的。因此，CD 63的消耗导致proNE向成熟NE的加工减少和组成性分泌减少。此外，CD 63耗尽的细胞表现出缺乏形态正常的颗粒，但含有MPO阳性的细胞质空泡，缺乏proNE和NE。总的来说，我们的数据表明，颗粒蛋白质可能合作的目标，CD 63可以参与ER或高尔基体出口，细胞滞留，颗粒前NE储存成熟NE的目标。
Targeting mechanisms of neutrophil elastase (NE) and other luminal proteins stored in myeloperoxidase (MPO)-positive secretory lysosomes/primary granules of neutrophils are unknown. These granules contain an integral membrane protein, CD63, with an adaptor protein-3-dependent granule delivery system. Therefore, we hypothesized that CD63 cooperates in granule delivery of the precursor of NE (proNE). Supporting this hypothesis, an association was demonstrated between CD63 and proNE upon coexpression in COS cells. This also involved augmented cellular retention of proNE requiring intact large extracellular loop of CD63. Furthermore, depletion of CD63 in promyelocytic HL-60 cells with RNA interference or a CD63 mutant caused reduction of cellular NE. However, the proNE steady-state level was similar to wild type in CD63-depleted clones, making it feasible to examine possible effects of CD63 on NE trafficking. Thus, depletion of CD63 led to reduced processing of proNE into mature NE and reduced constitutive secretion. Furthermore, CD63-depleted cells showed a lack of morphologically normal granules, but contained MPO-positive cytoplasmic vacuoles with a lack of proNE and NE. Collectively, our data suggest that granule proteins may cooperate in targeting; CD63 can be involved in ER or Golgi export, cellular retention, and granule targeting of proNE before storage as mature NE.