CD3ε胞浆区Tyr突变阻断下游的细胞凋亡信号传递

Mutation of tyrosines in the cytoplasmic domain of CD3ε blocks the apoptotic signaling pathway of T lymphocytes

目的：利用稳定表达ＣＤ８ε融合分子的细胞凋亡模型，研究其ＣＤ３εＩＴＡＭ中两个酪氨酸的突变对细胞凋亡信号传递及相关基因表达的影响。方法：将稳定表达ＣＤ８ε融合分子及其３种突变分子的Ｔ淋巴细胞分别用抗ＣＤ８单抗刺激后，检测４种细胞蛋白酪氨酸磷酸化和胞浆Ｃａ２＋浓度的变化以及细胞凋亡相关基因表达。结果：抗体刺激后，表达ＣＤ８ε的细胞与表达其３种突变分子的细胞相比，其蛋白磷酸化增加，胞浆Ｃａ２＋浓度升高；立早基因ｎｕｒ７７和细胞凋亡基因ｆａｓ表达水平升高。结论：首次发现ＣＤ３εＩＴＡＭ中两个酪氨酸的突变阻断了ＣＤ３介导的凋亡信号传导途径，并影响ｎｕｒ７７和ｆａｓ基因的表达。

Objective:To study the effect of the mutation of two tyrosines in CD3ε ITAM on apoptotic signaling pathway by using the cell lines stably expressed CD8ε chimera molecule and its mutants of tyrosines to phenolanalines in CD3ε ITAM as models.Methods:The cells were stimulated with anti CD8 monoclonal antibody and the protein phosphorylation was analyzed by Western blot,concentration of Ca 2+ analyzed by flow cytometry and nur77 and fas gene expressions determined by Northern blot and RT PCR respectively.Results:It was showed that the protein phosphorylations and intracellular concentrations of Ca 2+ were increased,nur77 and fas gene expressions upregulated in the cells with expression of CD8ε +,but not in the cells with the expression of CD8ε mutants.Conclusion:It was found at the first time that mutation of any one of the two tyrosines in CD3ε ITAM blocks the apoptotic signaling pathway mediated by CD3ε molecule.