Houchins J P, Lanier L L, Niemi E C, Phillips J H, Ryan J C
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55455, USA.
J Immunol. 1997 Apr 15;158(8):3603-9.
NKG2 is a small family of type II transmembrane proteins possessing extracellular C-type lectin domains expressed primarily on NK cells. The function of these proteins is unknown. We have developed mAbs that recognize NKG2 family members on Western blots. Examination of cell extracts from NK cell clones demonstrates that individual NKG2 family members are expressed on subsets of NK cells. Because the anti-NKG2 mAb do not react with the cell surface Ag, signaling function was studied by generating cell lines that express a chimeric receptor consisting of a cytoplasmic and transmembrane domain from NKG2-A or NKG2-C fused to the extracellular segment of mouse NKR-P1C (NK1.1 Ag). Transfectants of the rat NK cell line, RNK-16, were tested for the effect of anti-NK1.1 mAb on cytolytic activity against the FcR+ target cell lines, P388D1 and P815. The anti-NK1.1 mAb stimulated lytic activity and calcium mobilization in the NK cell line expressing the NKG2-C/NKR-P1C chimeric receptor. By contrast, anti-NK1.1 inhibited the lytic activity and failed to stimulate a calcium response in cells expressing the NKG2-A/NKR-P1C chimeric receptor. Immunoprecipitation experiments demonstrated that the inhibitory cytoplasmic tyrosine phosphatase SHP-1 selectively associates with the NKG2-A/NKR-P1C chimeric receptor, but not with the stimulatory NKG2-C/NKR-P1C receptor. These data indicate that NKG2-A and NKG2-C deliver, respectively, inhibitory and activating transmembrane signals in NK cells.
NKG2是一个II型跨膜蛋白的小家族，具有主要在自然杀伤（NK）细胞上表达的细胞外C型凝集素结构域。这些蛋白的功能尚不清楚。我们已经开发出在蛋白质免疫印迹法中能识别NKG2家族成员的单克隆抗体（mAb）。对NK细胞克隆的细胞提取物进行检测表明，单个NKG2家族成员在NK细胞亚群上表达。由于抗NKG2单克隆抗体不与细胞表面抗原发生反应，因此通过生成表达嵌合受体的细胞系来研究信号传导功能，该嵌合受体由来自NKG2 - A或NKG2 - C的细胞质和跨膜结构域与小鼠NKR - P1C（NK1.1抗原）的细胞外片段融合而成。对大鼠NK细胞系RNK - 16的转染子进行测试，以检测抗NK1.1单克隆抗体对针对FcR +靶细胞系P388D1和P815的细胞溶解活性的影响。抗NK1.1单克隆抗体在表达NKG2 - C / NKR - P1C嵌合受体的NK细胞系中刺激了溶解活性和钙动员。相比之下，抗NK1.1抑制了表达NKG2 - A / NKR - P1C嵌合受体的细胞中的溶解活性，并且未能刺激钙反应。免疫沉淀实验表明，抑制性细胞质酪氨酸磷酸酶SHP - 1选择性地与NKG2 - A / NKR - P1C嵌合受体结合，但不与刺激性NKG2 - C / NKR - P1C受体结合。这些数据表明，NKG2 - A和NKG2 - C分别在NK细胞中传递抑制性和激活性跨膜信号。
