Regulation of oxidative stress-induced calcium release by phosphatidylinositol 3-kinase and Bruton's tyrosine kinase in B cells.
Regulation of oxidative stress-induced calcium release by phosphatidylinositol 3-kinase and Bruton's tyrosine kinase in B cells.
复制标题
DOI：
10.1073/pnas.130198197
复制
发表时间：
2000-06
影响因子：
11.1
通讯作者：
S. Qin;E. Stadtman;P. Chock
中科院分区：
文献类型：
--
作者：
S. Qin;E. Stadtman;P. Chock
过氧化氢刺激酪氨酸激酶依赖性钙从细胞内储存释放，这被认为是通过B细胞中酪氨酸磷酸化机制激活磷脂酶C γ 2（PLC γ 2）实现的。我们发现，在B细胞中，H（2）O（2）诱导PLC γ 2上的酪氨酸磷酸化和磷脂酰肌醇3-激酶（PI 3 K）的激活，并且磷脂酰肌醇3-激酶抑制剂Wortmannin部分抑制H（2）O（2）诱导的钙释放，而不影响PLC γ 2上的酪氨酸磷酸化。过表达的人布鲁顿酪氨酸激酶（Btk）可被H（2）O（2）激活，几乎完全克服了渥曼青霉素对钙释放的抑制。通过提高Btk浓度来逆转Wortmannin的抑制作用似乎是H（2）O（2）介导的效应所独有的，因为Btk未能克服Wortmannin对B细胞受体触发的钙动员的抑制作用。免疫印迹分析显示，Btk与几种酪氨酸磷酸化蛋白质（包括PLC γ 2）形成稳定的复合物，仅在H2 O2刺激的Btk过表达细胞中。总之，我们的数据与PIP 3和/或高浓度的Btk将活化的PLC γ 2靶向其底物位点以获得最大催化效率的观点一致。
Hydrogen peroxide stimulates a tyrosine kinase-dependent calcium release from intracellular stores, which is assumed to be achieved through the activation of phospholipase Cgamma2 (PLCgamma2) via a tyrosine phosphorylation mechanism in B cells. Here we show that H(2)O(2) induces both tyrosine phosphorylation on PLCgamma2 and the activation of phosphatidylinositol 3-kinase (PI3K) in B cells, and that the phosphatidylinositol 3-kinase inhibitor, Wortmannin, partially inhibited the H(2)O(2)-induced calcium release without affecting tyrosine phosphorylation on PLCgamma2. Overexpression of human Bruton's tyrosine kinase (Btk), which was activated by H(2)O(2), almost completely overcame the inhibition of calcium release by Wortmannin. The reversal of Wortmannin's inhibition by enhancing Btk concentration seemed unique to the H(2)O(2)-mediated effect, because Btk failed to overcome the inhibition of Wortmannin on B cell receptor-triggered calcium mobilization. Immunoblot analysis revealed that Btk formed stable complexes with several tyrosine-phosphorylated proteins, including PLCgamma2, only in Btk-overexpressed cells on H(2)O(2) stimulation. Together, our data are consistent with the notion that PIP3 and/or a high concentration of Btk target the activated PLCgamma2 to its substrate site for maximal catalytic efficiency.