Editors' ChoiceImmunology

Actin' Up in the Immune Synapse

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Science's STKE  23 Sep 2003:
Vol. 2003, Issue 201, pp. tw374
DOI: 10.1126/stke.2003.201.tw374

A T cell engages an antigen presenting cell (APC) through a synaptic connection (the immune synapse) that subsequently controls T cell activation and function. This association recruits key actin regulatory proteins to the synapse, including Wiskott-Aldrich syndrome protein (WASP) and the small guanosine triphosphatase Cdc42, which activates WASP contributing to localized actin polymerization at the synapses. T cells lacking WASP show defects in signaling events downstream of T cell receptor activation, as well as in proliferation and cytokine production. Labno et al. report that T cells lacking Itk, a Tec family kinase required for T cell receptor signaling, exhibited this same phenotype, as well as defects in actin assembly at the synapse and unstable conjugate formation with APCs. WASP was efficiently recruited to the synapse in Itk-null T cells, but not in its activated form. In addition, Itk-null T cells showed a decrease in activated Cd42 at the immune synapse. The authors speculate that Itk could activate Cdc42. The findings show that Itk is an essential component of the actin regulatory cascade in activated T cells that are engaged with APCs and supports the general concept of localized actin responses in cells.

C. M. Labno, C. M. Lewis, D. You, D. W. Leung, A. Takesono, N. Kamberos, A. Seth, L. D. Finkelstein, M. K. Rosen, P. L. Schwartzberg, J. K. Burkhardt, Itk functions to control actin polymerization at the immune synapse through localized activation of Cdc42 and WASP. Current Biol. 13, 1619-1624 (2003). [Online Journal]