Kinase-independent functions for Itk in TCR-induced regulation of Vav and the actin cytoskeleton

被引:107
作者
Dombroski, D
Houghtling, RA
Labno, CM
Precht, P
Takesono, A
Caplen, NJ
Billadeau, DD
Wange, RL
Burkhardt, JK
Schwartzberg, PL
机构
[1] NHGRI, NIH, Bethesda, MD 20892 USA
[2] Univ Chicago, Dept Pathol, Chicago, IL 60637 USA
[3] NIA, Gerontol Res Ctr, NIH, Baltimore, MD 21224 USA
[4] Mayo Clin & Mayo Fdn, Dept Immunol, Rochester, MN 55905 USA
[5] Mayo Clin & Mayo Fdn, Div Oncol Res, Rochester, MN 55905 USA
[6] Childrens Hosp Philadelphia, Dept Pathol, Philadelphia, PA 19104 USA
[7] Univ Penn, Philadelphia, PA 19104 USA
关键词
D O I
10.4049/jimmunol.174.3.1385
中图分类号
R392 [医学免疫学]; Q939.91 [免疫学];
学科分类号
100102 ;
摘要
The Tee family kinase Itk is an important regulator of Ca2+ mobilization and is required for in vivo responses to Th-2-inducing agents. Recent data also implicate Itk in TCR-induced regulation of the actin cytoskeleton. We have evaluated the requirements for Itk function in TCR-induced actin polarization. Reduction of Itk expression via small interfering RNA treatment of the Jurkat human T lymphoma cell line or human peripheral blood T cells disrupted TCR-induced actin polarization, a defect that correlated with decreased recruitment of the Vav guanine nucleotide exchange factor to the site of Ag contact. Vav localization and actin polarization could be rescued by re-expression of either wild-type or kinase-inactive murine Itk but not by Itk containing mutations affecting the pleckstrin homology or Src homology 2 domains. Additionally.. we find that Itk is constitutively associated with Vav. Loss of Itk expression did not alter gross patterns of Vav tyrosine phosphorylation but appeared to disrupt the interactuons of Vav with SLP-76. Expression of membrane-targeted Vav, Vav-CAAX, can rescue the small interfering RNA to Itk-induced phenotype, implicating the alteration in Vav localization as directly contributing to the actin polarization defect. These data suggest a kinase-independent scaffolding function for Itk in the regulation of Vav localization and TCR-induced actin polarization.
引用
收藏
页码:1385 / 1392
页数:8
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