The Class II Phosphatidylinositol 3 kinase C2β Is Required for the Activation of the K+ Channel KCa3.1 and CD4 T-Cells
The Class II Phosphatidylinositol 3 kinase C2β Is Required for the Activation of the K+ Channel KCa3.1 and CD4 T-Cells
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DOI：
10.1091/mbc.e09-05-0390
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发表时间：
2009-09-01
影响因子：
3.3
通讯作者：
Skolnik, Edward Y.
中科院分区：
文献类型：
--
作者：
Srivastava, Shekhar;Di, Lie;Skolnik, Edward Y.
Ca2+激活的K+通道KCa3.1是Ca2+内流和随后的t细胞激活所必需的。我们之前的研究表明，核苷二磷酸激酶β (NDPK-B)，一种哺乳动物组氨酸激酶，直接磷酸化并激活KCa3.1，并且是激活人类CD4 T淋巴细胞所必需的。我们现在发现II类磷脂酰肌醇3激酶C2 β (PI3K-C2 β)被t细胞受体（TCR）激活，并在NDPK-B上游发挥作用，激活KCa3.1通道活性。siRNA降低PI3K-C2 β在人CD4 t细胞中的表达，导致KCa3.1通道活性受到抑制。抑制是由于磷脂酰肌醇3-磷酸[PI(3) P]的降低，因为用PI(3) P透析PI3K-C2 β sirna处理的t细胞恢复了KCa3.1通道的活性。此外，在KCa3.1转染的Jurkat t细胞中，PI3K-C2 β的过表达导致tcr刺激的KCa3.1激活和Ca2+内流增加，而PI3K-C2 β的沉默抑制了这两种反应。利用全内反射荧光显微镜和平面脂质双分子层，我们发现PI3K-C2 β与免疫突触外周微团中的Zap70和TCR共定位。这是第一次证明II类PI3K在t细胞激活中起关键作用。
The Ca2+-activated K+ channel KCa3.1 is required for Ca2+ influx and the subsequent activation of T-cells. We previously showed that nucleoside diphosphate kinase beta (NDPK-B), a mammalian histidine kinase, directly phosphorylates and activates KCa3.1 and is required for the activation of human CD4 T lymphocytes. We now show that the class II phosphatidylinositol 3 kinase C2 beta (PI3K-C2 beta) is activated by the T-cell receptor (TCR) and functions upstream of NDPK-B to activate KCa3.1 channel activity. Decreased expression of PI3K-C2 beta by siRNA in human CD4 T-cells resulted in inhibition of KCa3.1 channel activity. The inhibition was due to decreased phosphatidylinositol 3-phosphate [ PI( 3) P] because dialyzing PI3K-C2 beta siRNA-treated T-cells with PI(3) P rescued KCa3.1 channel activity. Moreover, overexpression of PI3K-C2 beta in KCa3.1-transfected Jurkat T-cells led to increased TCR-stimulated activation of KCa3.1 and Ca2+ influx, whereas silencing of PI3K-C2 beta inhibited both responses. Using total internal reflection fluorescence microscopy and planar lipid bilayers, we found that PI3K-C2 beta colocalized with Zap70 and the TCR in peripheral microclusters in the immunological synapse. This is the first demonstration that a class II PI3K plays a critical role in T-cell activation.