Israels S J, McMillan E M, Robertson C, Singhory S, McNicol A
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
Thromb Haemost. 1996 Apr;75(4):623-9.
Lysosomal Associated Membrane Protein-2 (LAMP-2) is an inherent component of lysosomal granule membranes in diverse cell types, including platelets. We examined platelets for evidence of LAMP-2 in dense granule membranes as CD63 has previously been shown to be present in both lysosomal and dense granule membranes. Immunological techniques were used to examine the localization of LAMP-2 in control platelets and those from an individual with Hermansky-Pudlak syndrome (HPS), a condition characterised by platelet dense granule deficiency. Immunoblotting studies demonstrated that LAMP-2 was enriched in a dense granule preparation. Flow cytometry of thrombin-stimulated control platelets was consistent with biphasic surface expression of LAMP-2. The early expression was accompanied by dense granule, but minimal lysosomal granule, release. The late expression was accompanied by additional lysosomal granule release only. Thrombin stimulation of HPS platelets showed only late, lysosome-associated LAMP-2 expression. Immunoelectron microscopy indicated the presence of LAMP-2 in the membranes of serotonin-containing granules as identified by an anti-serotonin polyclonal antibody. These data indicate that LAMP-2 is present in the membranes of platelet dense granules in addition to lysosomal granules, and has a similar distribution to CD63.
溶酶体相关膜蛋白2（LAMP-2）是多种细胞类型（包括血小板）中溶酶体颗粒膜的固有成分。由于先前已证明CD63存在于溶酶体和致密颗粒膜中，我们检测了血小板致密颗粒膜中LAMP-2的证据。采用免疫技术检测LAMP-2在对照血小板和患有Hermansky-Pudlak综合征（HPS）个体的血小板中的定位，HPS是一种以血小板致密颗粒缺乏为特征的疾病。免疫印迹研究表明，LAMP-2在致密颗粒制剂中富集。凝血酶刺激的对照血小板的流式细胞术与LAMP-2的双相表面表达一致。早期表达伴随着致密颗粒释放，但溶酶体颗粒释放极少。晚期表达仅伴随着额外的溶酶体颗粒释放。凝血酶刺激HPS血小板仅显示晚期、与溶酶体相关的LAMP-2表达。免疫电子显微镜显示，通过抗血清素多克隆抗体鉴定，含血清素颗粒的膜中存在LAMP-2。这些数据表明，LAMP-2除存在于溶酶体颗粒中外，还存在于血小板致密颗粒的膜中，并且与CD63具有相似的分布。
