A DOCK8-WIP-WASp complex links T cell receptors to the actin cytoskeleton
Erin Janssen, … , Francis W. Luscinskas, Raif S. Geha
Erin Janssen, … , Francis W. Luscinskas, Raif S. Geha
Published September 6, 2016
Citation Information: J Clin Invest. 2016;126(10):3837-3851. https://doi.org/10.1172/JCI85774.
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A DOCK8-WIP-WASp complex links T cell receptors to the actin cytoskeleton

Abstract

Wiskott-Aldrich syndrome (WAS) is associated with mutations in the WAS protein (WASp), which plays a critical role in the initiation of T cell receptor–driven (TCR-driven) actin polymerization. The clinical phenotype of WAS includes susceptibility to infection, allergy, autoimmunity, and malignancy and overlaps with the symptoms of dedicator of cytokinesis 8 (DOCK8) deficiency, suggesting that the 2 syndromes share common pathogenic mechanisms. Here, we demonstrated that the WASp-interacting protein (WIP) bridges DOCK8 to WASp and actin in T cells. We determined that the guanine nucleotide exchange factor activity of DOCK8 is essential for the integrity of the subcortical actin cytoskeleton as well as for TCR-driven WASp activation, F-actin assembly, immune synapse formation, actin foci formation, mechanotransduction, T cell transendothelial migration, and homing to lymph nodes, all of which also depend on WASp. These results indicate that DOCK8 and WASp are in the same signaling pathway that links TCRs to the actin cytoskeleton in TCR-driven actin assembly. Further, they provide an explanation for similarities in the clinical phenotypes of WAS and DOCK8 deficiency.

Authors

Erin Janssen, Mira Tohme, Mona Hedayat, Marion Leick, Sudha Kumari, Narayanaswamy Ramesh, Michel J. Massaad, Sumana Ullas, Veronica Azcutia, Christopher C. Goodnow, Katrina L. Randall, Qi Qiao, Hao Wu, Waleed Al-Herz, Dianne Cox, John Hartwig, Darrell J. Irvine, Francis W. Luscinskas, Raif S. Geha

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Figure 5

Defective actin cytoskeleton structure and function in DOCK8-deficient T cells.

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Defective actin cytoskeleton structure and function in DOCK8-deficient T...
(A) Representative EM images of the apical membrane of T cells stimulated with anti-CD3 mAb. Shown are the cytoskeletal actin fibers associated with the cytoplasmic side of the adherent plasma membranes. Results are representative of 2 experiments with T cells from 1 mouse of each strain. More than 50 cells were examined in each experiment. Scale bar: 200 nm. (B) Actin filament length in T cell membranes from the Dock8–/–, Dock8pri/pri, and WT mice represented in A; 114 WT T cells, 139 Dock8–/– T cells, and 120 Dock8pri/pri T cells were measured in 2 independent experiments. (C) Representative FACS analysis of FITC-phalloidin staining for F-actin in resting T cells from Dock8–/–, Dock8pri/pri, and WT mice and quantitative analysis of the results as a percentage of F-actin content in T cells from WT controls. Results are representative of 3 independent experiments using 3 mice from each strain. (D) Increase in the F-actin content of T cells from Dock8–/–, Dock8pri/pri, and WT mice following stimulation with anti-CD3 mAb. Results are expressed as the increase in the mean fluorescence intensity (MFI) of F-actin from the baseline (time 0). Results are representative of 3 independent experiments using 3 mice from each strain. Error bars in B and C and symbols and bars in D represent the mean ± SEM. ***P < 0.001, **P < 0.01, and *P < 0.05, by Student’s t test.