Kinase-Independent Functions for Itk in TCR-Induced Regulation of Vav and the Actin Cytoskeleton

摘要: The Tec family kinase Itk is an important regulator of Ca(2+) mobilization and required for in vivo responses to Th2-inducing agents. Recent data also implicate TCR-induced regulation the actin cytoskeleton. We have evaluated requirements function polarization. Reduction expression via small interfering RNA treatment Jurkat human T lymphoma cell line or peripheral blood cells disrupted polarization, a defect that correlated with decreased recruitment Vav guanine nucleotide exchange factor site Ag contact. localization polarization could be rescued by re-expression either wild-type kinase-inactive murine but not containing mutations affecting pleckstrin homology Src 2 domains. Additionally, we find constitutively associated Vav. Loss did alter gross patterns tyrosine phosphorylation appeared disrupt interactions SLP-76. Expression membrane-targeted Vav, Vav-CAAX, can rescue Itk-induced phenotype, implicating alteration as directly contributing defect. These suggest kinase-independent scaffolding