Aberrant subcellular targeting of the G185R neutrophil elastase mutant associated with severe congenital neutropenia induces premature apoptosis of differentiating promyelocytes
Aberrant subcellular targeting of the G185R neutrophil elastase mutant associated with severe congenital neutropenia induces premature apoptosis of differentiating promyelocytes
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DOI：
10.1182/blood-2004-07-2618
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发表时间：
2005-05-01
期刊：
影响因子：
20.3
通讯作者：
Avalos, BR
中科院分区：
文献类型：
--
作者：
Massullo, P;Druhan, LJ;Avalos, BR
编码中性粒细胞弹性蛋白酶(NE)的ELA2基因突变存在于大多数严重的先天性中性粒细胞减少症(SCN)患者中。然而，这些突变导致中性粒细胞减少的机制仍不清楚。为了研究突变的NE表达对粒细胞生成的影响，我们使用了逆转录病毒转导的HL-60早幼粒细胞系，G185R NE突变与严重的SCN表型相关。我们发现该突变酶可加速分化细胞的凋亡，但不能促进增殖细胞的凋亡。利用代谢标记、共聚焦免疫荧光显微镜和亚细胞组分的免疫印迹分析，我们还证明了G185R突变体被异常加工，并且主要定位于核膜和质膜，而不是野生型(WT)酶观察到的细胞质隔室。G185R突变体的表达似乎改变了适配器蛋白3(AP3)的亚细胞分布和表达，AP3负责将蛋白质从跨高尔基体运输到内体。这些观察结果进一步揭示了NE突变导致中性粒细胞减少的潜在机制，并提示G185R突变导致的严重SCN表型与分化中的髓系细胞异常蛋白运输和加速凋亡有关。(C)2005年，由美国血液病学会提供。
Mutations in the ELA2 gene encoding neutrophil elastase (NE) are present in most patients with severe congenital neutropenia (SCN). However, the mechanisms by which these mutations cause neutropenia remain unknown. To investigate the effects of mutant NE expression on granulopoiesis, we used the HL-60 promyelocytic cell line retrovirally transduced with the G185R NE mutant that is associated with a severe SCN phenotype. We show that the mutant enzyme accelerates apoptosis of differentiating but not of proliferating cells. Using metabolic labeling, confocal immunofluorescence microscopy, and immunoblot analysis of subcellular fractions, we also demonstrate that the G185R mutant is abnormally processed and localizes predominantly to the nuclear and plasma membranes rather than to the cytoplasmic compartment observed with the wildtype (WT) enzyme. Expression of the G185R mutant appeared to alter the subcellular distribution and expression of adaptor protein 3 (AP3), which traffics proteins from the trans-Golgi apparatus to the endosome. These observations provide further insight into potential mechanisms by which NE mutations cause neutropenia and suggest that abnormal protein trafficking and accelerated apoptosis of differentiating myeloid cells contribute to the severe SCN phenotype resulting from the G185R mutation. (c) 2005 by The American Society of Hematology.