Grujic Mirjana, Braga Tiago, Lukinius Agneta, Eloranta Maija-Leena, Knight Stefan D, Pejler Gunnar, Abrink Magnus
Department of Molecular Biosciences, Swedish University of Agricultural Sciences, The Biomedical Center, Box 575, 751 23 Uppsala, Sweden.
J Biol Chem. 2005 Sep 30;280(39):33411-8. doi: 10.1074/jbc.M501708200. Epub 2005 Jul 26.
Cytotoxic T lymphocytes eliminate infected and tumor cells mainly by perforin/granzyme-induced apoptosis. Earlier studies suggested that serglycin-proteoglycans form macromolecular complexes with granzymes and perforin in the cytotoxic granule. Serglycin-proteoglycans may also be involved in the delivery of the cytolytic machinery into target cells. We have developed a serglycin-deficient mouse strain, and here we studied the importance of serglycin-proteoglycans for various aspects of cytotoxic T lymphocyte function. 35SO4(2-) radiolabeling of serglycin-deficient cells demonstrated a dramatic reduction of incorporated label as compared with wild type cells, indicating that serglycin is by far the dominating proteoglycan species produced by the cytotoxic T lymphocyte. Moreover, lack of serglycin resulted in impaired ability of cytotoxic T lymphocytes to produce secretory granule of high electron density, although granule of lower electron density were produced both in wild type and serglycin-deficient cells. The serglycin deficiency did not affect the mRNA expression for granzyme A, granzyme B, or perforin. However, the storage of granzyme B, but not granzyme A, Fas ligand, or perforin, was severely defective in serglycin-deficient cells. Serglycin-deficient cells did not display defects in late cytotoxicity toward target cell lines. Taken together, these results point to a key role for serglycin in the storage of granzyme B and for secretory granule maturation but argue against a major role for serglycin in the apoptosis mediated by cytotoxic T lymphocytes.
细胞毒性T淋巴细胞主要通过穿孔素/颗粒酶诱导的细胞凋亡来清除受感染细胞和肿瘤细胞。早期研究表明，丝甘蛋白聚糖在细胞毒性颗粒中与颗粒酶和穿孔素形成大分子复合物。丝甘蛋白聚糖也可能参与将溶细胞机制传递到靶细胞中。我们培育了一种丝甘蛋白缺陷型小鼠品系，在此研究了丝甘蛋白聚糖对细胞毒性T淋巴细胞功能各个方面的重要性。与野生型细胞相比，对丝甘蛋白缺陷型细胞进行35SO4(2-)放射性标记显示掺入的标记显著减少，表明丝甘蛋白是细胞毒性T淋巴细胞产生的占主导地位的蛋白聚糖种类。此外，缺乏丝甘蛋白导致细胞毒性T淋巴细胞产生高电子密度分泌颗粒的能力受损，尽管野生型细胞和丝甘蛋白缺陷型细胞都能产生低电子密度颗粒。丝甘蛋白缺陷并不影响颗粒酶A、颗粒酶B或穿孔素的mRNA表达。然而，在丝甘蛋白缺陷型细胞中，颗粒酶B的储存严重缺陷，但颗粒酶A、Fas配体或穿孔素的储存没有缺陷。丝甘蛋白缺陷型细胞对靶细胞系的晚期细胞毒性没有表现出缺陷。综上所述，这些结果表明丝甘蛋白在颗粒酶B的储存和分泌颗粒成熟中起关键作用，但不支持丝甘蛋白在细胞毒性T淋巴细胞介导的细胞凋亡中起主要作用。
