Deficiency of PTEN in Jurkat T cells causes constitutive localization of Itk to the plasma membrane and hyperresponsiveness to CD3 stimulation
Deficiency of PTEN in Jurkat T cells causes constitutive localization of Itk to the plasma membrane and hyperresponsiveness to CD3 stimulation
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DOI：
10.1128/mcb.20.18.6945-6957.2000
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发表时间：
2000-09-01
影响因子：
5.3
通讯作者：
Wange, RL
中科院分区：
文献类型：
--
作者：
Shan, XC;Czar, MJ;Wange, RL
与D3-磷酸化磷脂酰肌醇（PI）结合的普列克底物蛋白同源（PH）结构域提供了将蛋白质募集至质膜的可逆手段，其中亚细胞定位的所得变化在多种细胞内信号传导途径的激活中起关键作用。以前我们发现，T细胞特异性的PH结构域的激酶Itk是组成性膜相关的Jurkat T细胞。考虑到密切相关的B细胞激酶Btk几乎完全是胞质的，这种分布是出乎意料的。除了Itk的组成性膜结合，未刺激的JTAg T细胞还表现出Ser-473上Akt的组成性磷酸化，这表明质膜中磷脂酰肌醇3-激酶（PI 3 K）产物PI-3，4-P-2和PI-3，4，5-P-3的基础水平升高。在这里，我们描述了一个缺陷的D3磷酸肌醇磷酸酶，PTEN，在Jurkat和JTAg T细胞，导致不受管制的PH结构域与质膜的相互作用的表达。通过PI 3 K抑制剂或通过表达PTEN抑制D3磷酸化，阻断了Ser-473上Akt的组成性磷酸化，并导致Itk重新分布到胞质溶胶中。PTEN缺陷型细胞也对T细胞受体（TCR）刺激反应过度，如通过Itk激酶活性、磷脂酶C-γ 1的酪氨酸磷酸化和Erk的活化所测量的，与PTEN充满型细胞中的那些相比。这些数据支持的想法，PH结构域介导的协会与质膜所需的Itk激活，提供了证据的负调控作用的PTEN在TCR刺激，并建议信号模型的基础上的结果从Jurkat T细胞系可能低估的作用PI 3 K在TCR信号。
Pleckstrin homology (PH) domain binding to D3-phosphorylated phosphatidylinositides (PI) provides a reversible means of recruiting proteins to the plasma membrane, with the resultant change in subcellular localization playing a key role in the activation of multiple intracellular signaling pathways. Previously we found that the T-cell-specific PH domain-containing kinase Itk is constitutively membrane associated in Jurkat T cells. This distribution was unexpected given that the closely related B-cell kinase, Btk, is almost exclusively cytosolic. In addition to constitutive membrane association of Itk, unstimulated JTAg T cells also exhibited constitutive phosphorylation of Akt on Ser-473, an indication of elevated basal levels of the phosphatidylinositol 3-kinase (PI3K) products PI-3,4-P-2 and PI-3,4,5-P-3 in the plasma membrane. Here we describe a defect in expression of the D3 phosphoinositide phosphatase, PTEN, in Jurkat and JTAg T cells that leads to unregulated PH domain interactions with the plasma membrane. Inhibition of D3 phosphorylation by PI3K inhibitors, or by expression of PTEN, blocked constitutive phosphorylation of Akt on Ser-473 and caused Itk to redistribute to the cytosol. The PTEN-deficient cells were also hyperresponsive to T-cell receptor (TCR) stimulation, as measured by Itk kinase activity, tyrosine phosphorylation of phospholipase C-gamma 1, and activation of Erk compared to those in PTEN-replete cells. These data support the idea that PH domain-mediated association with the plasma membrane is required for Itk activation, provide evidence for a negative regulatory role of PTEN in TCR stimulation, and suggest that signaling models based on results from Jurkat T-cell lines may underestimate the role of PI3K in TCR signaling.