Hematopoietic lineage cell-specific protein 1 is recruited to the immunological synapse by IL-2-inducible T cell kinase and regulates phospholipase Cgamma1 Microcluster dynamics during T cell spreading.
Hematopoietic lineage cell-specific protein 1 is recruited to the immunological synapse by IL-2-inducible T cell kinase and regulates phospholipase Cgamma1 Microcluster dynamics during T cell spreading.
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DOI：
10.4049/jimmunol.0900973
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发表时间：
2009-12-01
期刊：
影响因子：
--
通讯作者：
Burkhardt JK
中科院分区：
文献类型：
--
作者：
Carrizosa E;Gomez TS;Labno CM;Klos Dehring DA;Liu X;Freedman BD;Billadeau DD;Burkhardt JK
生产性T细胞活化需要肌动蛋白细胞骨架的有效重组。我们以前表明，肌动蛋白调节蛋白，造血谱系细胞特异性蛋白1（HS 1），是所需的F-肌动蛋白和Vav 1在免疫突触的稳定和有效的钙反应。Tec家族激酶IL-2诱导的T细胞激酶（Itk）调节T细胞活化的类似方面，表明这些蛋白质在相同的途径中起作用。使用视频显微镜，我们发现，缺乏Itk或HS 1的T细胞在肌动蛋白反应中表现出类似的缺陷，在TCR刺激后延长不稳定的片状伪足突起。HS 1和Itk可以从T细胞裂解物中共免疫沉淀，并且GST-下拉研究表明Itk的Src同源2结构域直接结合HS 1中的两个磷酸酪氨酸。在Itk的情况下，或在过表达Itk Src同源性2结构域突变体的T细胞中，HS 1未能定位于免疫突触，表明Itk用于将HS 1募集到TCR接合的位点。由于Itk是磷脂酶C（PLC）γ1磷酸化和钙库释放所必需的，因此我们更详细地研究了HS 1 −/− T细胞中的钙信号通路。作为对TCR结合的响应，缺乏HS 1的T细胞表现出减少的钙库释放，但TCR依赖性PLCγ1磷酸化是完整的，表明HS 1在钙信号传导中的作用与Itk不同。HS 1缺陷型T细胞表现出PLCγ1的细胞骨架结合缺陷和PLCγ1微簇的形成改变。我们的结论是，HS 1作为Itk的效应子在T细胞肌动蛋白调节途径中发挥作用，并指导PLCγ1信号复合物的空间组织。
Productive T cell activation requires efficient reorganization of the actin cytoskeleton. We showed previously that the actin-regulatory protein, hematopoietic lineage cell-specific protein 1 (HS1), is required for the stabilization of F-actin and Vav1 at the immunological synapse and for efficient calcium responses. The Tec family kinase IL-2-inducible T cell kinase (Itk) regulates similar aspects of T cell activation, suggesting that these proteins act in the same pathway. Using video microscopy, we show that T cells lacking Itk or HS1 exhibited similar defects in actin responses, extending unstable lamellipodial protrusions upon TCR stimulation. HS1 and Itk could be coimmunoprecipitated from T cell lysates, and GST-pulldown studies showed that Itk’s Src homology 2 domain binds directly to two phosphotyrosines in HS1. In the absence of Itk, or in T cells overexpressing an Itk Src homology 2 domain mutant, HS1 failed to localize to the immunological synapse, indicating that Itk serves to recruit HS1 to sites of TCR engagement. Because Itk is required for phospholipase C (PLC)γ1 phosphorylation and calcium store release, we examined the calcium signaling pathway in HS1−/− T cells in greater detail. In response to TCR engagement, T cells lacking HS1 exhibited diminished calcium store release, but TCR-dependent PLCγ1 phosphorylation was intact, indicating that HS1’s role in calcium signaling is distinct from that of Itk. HS1-deficient T cells exhibited defective cytoskeletal association of PLCγ1 and altered formation of PLCγ1 microclusters. We conclude that HS1 functions as an effector of Itk in the T cell actin-regulatory pathway, and directs the spatial organization of PLCγ1 signaling complexes.
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