T-cell receptor ligation causes Wiskott-Aldrich syndrome protein degradation and F-actin assembly downregulation

Yuko Watanabe, Yoji Sasahara, Narayanaswamy Ramesh, Michel J. Massaad, Chung Yeng Looi, Satoru Kumaki, Shigeo Kure, Raif S. Geha, Shigeru Tsuchiya

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Background: Wiskott-Aldrich syndrome protein (WASP) links T-cell receptor (TCR) signaling to the actin cytoskeleton. WASP is normally protected from degradation by the Ca++-dependent protease calpain and by the proteasome because of its interaction with the WASP-interacting protein. Objective: We investigated whether WASP is degraded after TCR ligation and whether its degradation downregulates F-actin assembly caused by TCR ligation. Methods: Primary T cells, Jurkat T cells, and transfected 293T cells were used in immunoprecipitation experiments. Intracellular F-actin content was measured in splenic T cells from wild-type, WASP-deficient, and c-Casitas B-lineage lymphoma (Cbl)-b-deficient mice by using flow cytometry. Calpeptin and MG-132 were used to inhibit calpain and the proteasome, respectively. Results: A fraction of WASP in T cells was degraded by calpain and by the ubiquitin-proteasome pathway after TCR ligation. The Cbl-b and c-Cbl E3 ubiquitin ligases associated with WASP after TCR signaling and caused its ubiquitination. Inhibition of calpain and lack of Cbl-b resulted in a significantly more sustained increase in F-actin content after TCR ligation in wild-type T cells but not in WASP-deficient T cells. Conclusion: TCR ligation causes WASP to be degraded by calpain and to be ubiquitinated by Cbl family E3 ligases, which targets it for destruction by the proteasome. WASP degradation might provide a mechanism for regulating WASP-dependent TCR-driven assembly of F-actin.

Original languageEnglish
Pages (from-to)648-655.e1
JournalJournal of Allergy and Clinical Immunology
Volume132
Issue number3
DOIs
Publication statusPublished - 2013 Sep

Keywords

  • Cbl family proteins
  • F-actin
  • T-cell receptor
  • Wiskott-Aldrich syndrome
  • Wiskott-Aldrich syndrome protein
  • calpain
  • proteasome
  • ubiquitination

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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