Ebnet K, Hausmann M, Lehmann-Grube F, Müllbacher A, Kopf M, Lamers M, Simon M M
Max-Planck-Institut für Immunbiologie, Freiburg, Germany.
EMBO J. 1995 Sep 1;14(17):4230-9. doi: 10.1002/j.1460-2075.1995.tb00097.x.
Granzyme A, a granule-associated serine proteinase of activated cytotoxic T cells and natural killer cells, has been reported to play a critical role in DNA fragmentation of target cells. To address the question of the biological role of granzyme A, we have now generated a granzyme A-deficient mouse mutant by homologous recombination. Western blot analysis, enzyme assays and reverse transcription-PCR confirmed the absence of granzyme A in activated T cells. In addition, deletion of granzyme A does not alter the expression patterns of other granule components, such as granzymes B-G and perforin. Granzyme A-deficient mice are healthy and show normal hematopoietic development. Most notably, their in vitro- and ex vivo-derived cytotoxic T cells and natural killer cells are indistinguishable from those of normal mice in causing membrane disruption, apoptosis and DNA fragmentation in target cells. Furthermore, granzyme A-deficient mice readily recover from both lymphocytic choriomeningitis virus and Listeria monocytogenes infections and eradicate syngeneic tumors with kinetics similar to the wild-type strain. These results demonstrate that granzyme A does not play a primary role in cell-mediated cytotoxicity, as has been assumed previously.
颗粒酶A是活化的细胞毒性T细胞和自然杀伤细胞中与颗粒相关的丝氨酸蛋白酶，据报道其在靶细胞的DNA片段化过程中起关键作用。为了解决颗粒酶A的生物学作用问题，我们现在通过同源重组产生了一种颗粒酶A缺陷型小鼠突变体。蛋白质免疫印迹分析、酶活性测定和逆转录-聚合酶链反应证实活化的T细胞中不存在颗粒酶A。此外，颗粒酶A的缺失不会改变其他颗粒成分的表达模式，如颗粒酶B-G和穿孔素。颗粒酶A缺陷型小鼠健康，造血发育正常。最值得注意的是，它们体外和体内产生的细胞毒性T细胞和自然杀伤细胞在导致靶细胞膜破坏、凋亡和DNA片段化方面与正常小鼠的细胞无异。此外，颗粒酶A缺陷型小鼠很容易从淋巴细胞性脉络丛脑膜炎病毒和单核细胞增生李斯特菌感染中恢复，并以与野生型菌株相似的动力学清除同基因肿瘤。这些结果表明，颗粒酶A并不像之前所认为的那样在细胞介导的细胞毒性中起主要作用。
