IONIZING-RADIATION STIMULATES UNIDENTIFIED TYROSINE-SPECIFIC PROTEIN-KINASES IN HUMAN LYMPHOCYTE-B PRECURSORS, TRIGGERING APOPTOSIS AND CLONOGENIC CELL-DEATH
IONIZING-RADIATION STIMULATES UNIDENTIFIED TYROSINE-SPECIFIC PROTEIN-KINASES IN HUMAN LYMPHOCYTE-B PRECURSORS, TRIGGERING APOPTOSIS AND CLONOGENIC CELL-DEATH
复制标题
DOI：
10.1073/pnas.89.19.9005
复制
发表时间：
1992-10-01
影响因子：
11.1
通讯作者：
SCHIEVEN, GL
中科院分区：
文献类型：
--
作者：
UCKUN, FM;TUELAHLGREN, L;SCHIEVEN, GL
关于电离辐射对细胞质信号转导途径的影响，目前所知甚少。在这里，我们表明电离辐射诱导增强了人b淋巴细胞前体中多种底物的酪氨酸磷酸化。在用钒酸盐（一种有效的蛋白-酪氨酸-磷酸酶（PTPase）抑制剂）预处理的细胞中也观察到这种对电离辐射的反应，磷酸化酪氨酸[Val5]血管紧张素II磷酸酶测定显示，受辐射细胞中PTPase活性没有下降。因此，辐照b淋巴细胞前体中酪氨酸磷酸化的增强不是由抑制细胞总PTPase活性引起的。使用抗磷酸酪氨酸抗体的免疫复合物激酶检测显示，辐照细胞免疫沉淀物中的蛋白酪氨酸激酶（PTK）活性增强，PTK抑制剂染料木素和herbimycin有效地阻止了辐射诱导的酪氨酸磷酸化。使用针对p59fyn、p56/p53lyn、p55blk和p56lck独特氨基酸序列制备的抗体，对辐照和未辐照的b淋巴细胞前体进行免疫复合物激酶检测，结果表明，这些src家族酪氨酸激酶并不是在抗磷酸酪氨酸抗体免疫沉淀中增强酪氨酸激酶活性或增强多种底物酪氨酸磷酸化的主要PTKs。因此，我们的研究结果支持电离辐射通过刺激尚未确定的PTKs诱导b淋巴细胞前体酪氨酸磷酸化增强的假设。酪氨酸磷酸化似乎是辐射诱导的细胞凋亡和克隆性细胞死亡的重要近端步骤，因为抑制PTK可防止DNA断裂和受辐射b淋巴细胞前体克隆性的丧失。由于PTK在细胞功能和增殖的调节中发挥着多种作用，PTK级联的激活，如本报告所述，可能解释电离辐射对b淋巴细胞及其前体细胞功能的一些多效性影响。
Very little is known regarding the effects of ionizing radiation on cytoplasmic signal transduction pathways. Here, we show that ionizing radiation induces enhanced tyrosine phosphorylation of multiple substrates in human B-lymphocyte precursors. This response to ionizing radiation was also observed in cells pretreated with vanadate, a potent protein-tyrosine-phosphatase (PTPase) inhibitor, and phosphotyrosyl [Val5]angiotensin II phosphatase assays showed no decreased PTPase activity in irradiated cells. Thus, enhanced tyrosine phosphorylation in irradiated B-lymphocyte precursors is not triggered by inhibition of total cellular PTPase activity. Immune-complex kinase assays using anti-phosphotyrosine antibodies demonstrated enhanced protein-tyrosine kinase (PTK) activity in the immunoprecipitates from irradiated cells, and the PTK inhibitors genistein and herbimycin effectively prevented radiation-induced tyrosine phosphorylation. Immune-complex kinase assays on irradiated and unirradiated B-lymphocyte precursors using antibodies prepared against unique amino acid sequences of p59fyn, p56/p53lyn, p55blk, and p56lck demonstrated that these Src-family tyrosine kinases were not the primary PTKs responsible for enhanced tyrosine kinase activity in the anti-phosphotyrosine antibody immunoprecipitates or for enhanced tyrosine phosphorylation of multiple substrates. Thus, our findings favor the hypothesis that ionizing radiation induces enhanced tyrosine phosphorylation in B-lymphocyte precursors by stimulation of as yet unidentified PTKs. Tyrosine phosphorylation appears to be an important proximal step in radiation-induced apoptosis and clonogenic cell death because inhibition of PTK prevents DNA fragmentation and loss of clonogenicity of irradiated B-lymphocyte precursors. Since PTKs play myriad roles in the regulation of cell function and proliferation, the activation of a PTK cascade, as detailed in this report, may explain some of the pleiotropic effects of ionizing radiation on cellular functions of B-lymphocytes and their precursors.