天花粉蛋白抑制TCR介导的Jurkat T 细胞蛋白酪氨酸磷酸化以及PLCγ1磷酸化

The inhibitory effect of trichosanthin on phosphorylation of TCR triggered protein tyrosine and of PLCγ1 in Jurkat T cells

目的研究天花粉蛋白（Ｔｋ）抑制Ｔ细胞增殖的作用机理。方法以抗ＣＤ３的ＭｃＡｂ刺激ＪｕｒｋａｔＴ细胞增殖，以３Ｈ－ＴｄＲ同位素掺入法观察Ｔｋ对其抑制作用。用免疫沉淀和免疫印迹法测定胞浆蛋白酪氨酸磷酸化情况。结果Ｔｋ能够抑制ＣＤ３ＭｃＡｂ刺激的ＪｕｒｋａｔＴ细胞的增殖，并且经Ｔｋ脉冲处理后的ＪｕｒｋａｔＴ细胞对ＣＤ３ＭｃＡｂ活化作用的反应降低。深入分析后发现，在Ｔｋ作用下胞浆蛋白酪氨酸磷酸化水平降低，经ＰＬＣγ１免疫沉淀后，发现ＰＬＣγ１的磷酸化也能够被Ｔｋ作用所抑制。结论Ｔｋ对Ｔ细胞活化的抑制涉及并经由ＴＣＲ的激活信号传导。

Objective To study the inhibitory mechanism of trichosanthin on T cell proliferation. Methods Jurkat T cells were stimulated with anti CD3 McAb, and the Tk's inhibition on its proliferation was analyzed using 3 H TdR incorporation method. By way of immunoprecipitation and immunoblotting, the cytosolic protein tyrosine phosphorylation was examined. Results Trichosanthin could inhibit the proliferation of Jurkat T cells which were induced by anti CD3 McAb. T cells which were pulsed with Tk revealed low response to anti CD3 McAb stimulation. Furthermore, the protein tyrosine phosphorylation was suppressed in T cells after Tk treatment. By immunoprecipitating PLCγ1, it has been shown that the phosphorylation of PLCγ1 could be inhibited by Tk. Conclusions The inhibitory mechanism of Tk on T cell proliferation was relevant to TCR signaling that the cytosolic protein tyrosine phosphorylation was inhibited.