| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* Institut National de la Santé et de la Recherche Médicale, Unité 891, Centre de Recherche en Cancérologie de Marseille; Institut Paoli-Calmettes; and Université Méditerranée, Marseille, France;
Institut National de la Santé et de la Recherche Médicale, Unité 790, Généthon, Evry, France; and
Department of Medicine, Division of Nephrology, McGill University Health Centre, Montreal, Québec, Canada
Dok-4 (downstream of tyrosine kinase-4) is a recently identified member of the Dok family of adaptor proteins, which are characterized by an amino-terminal pleckstrin homology domain, a phosphotyrosine-binding domain, and a carboxyl-terminal region containing several tyrosines and poly-proline-rich motifs. Two members of the Dok family, Dok-1 and Dok-2, have already been described as negative regulators in T cells. However, the function of Dok-4, which is also expressed in T cells, remains unknown. In this study, we report that Dok-4 is phosphorylated after TCR engagement and shuttled within the cytoplasm of T cells before being recruited to the polarized microtubule organizing center after the formation of the immunological synapse. Loss-of-function experiments using RNA interference constructs show that Dok-4 is a negative regulator of ERK phosphorylation, IL-2 promoter activity, and T cell proliferation. Exogenous expression of wild-type Dok-4 induces a significant activation of Rap1, which is involved in the regulation of ERK. The pleckstrin homology domain of Dok-4 is required both for its cytoplasmic shuttling and relocalization as well as for its inhibitory properties on T cell activation. Thus, Dok-4 represents a novel negative regulator of T cells.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by grants from Institut National de la Santé et de la Recherche Médicale, the Ligue Nationale Contre le Cancer, the Institut National du Cancer (no. PL-06026), the Association pour la Recherche contre le Cancer (no. 4202), Génopole Recherche and Association Française contre les Myopathies (to A. Galy), and from the Kidney Foundation of Canada and the Canadian Institutes of Health Research (to S. Lemay). A. Gérard was supported by fellowships from the Ministère de l’Enseignement Supérieur et de la Recherche and the Ligue Nationale Contre le Cancer. C. Fos was supported by fellowships from the Ministère de l’Enseignement Supérieur et de la Recherche and the Fondation pour la Recherche Médicale. G. Guittard was supported by fellowships from the Institut National de la Santé et de la Recherche Médicale/Région Provence-Alpes Côte d’Azur (PACA) and the Ligue Nationale Contre le Cancer. D. Compagno was supported by a fellowship from the Fondation de France.
2 Current address: University of California, San Francisco, Division of Pathology, 513 Parnassus Avenue, San Francisco, CA 94143.
3 Current address: Division of Cellular Biology, La Jolla Institute for Allergy & Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037.
4 Current address: Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Departamento de Química Biológica, Buenos Aires, Argentina.
5 Address correspondence and reprint requests to Dr. Jacques A. Nunès, Centre de Recherche en Cancérologie de Marseille, 27 Bd Lei Roure, 13009 Marseille, France. E-mail address: jacques.nunes{at}inserm.fr
6 Abbreviations used in this paper: Dok, downstream of tyrosine kinase; CMTMR, 5-(and-6)-(((4-chloromethyl)-benzoyl-amino)tetramethyl-rhodamine; IS, immunological synapse; MTOC, microtubule organizing center; PH, pleckstrin homology; PLC, phospholipase C; PTB, phosphotyrosine binding; PTK, protein tyrosine kinase; PY, phosphotyrosine; RNAi, RNA interference; SEE, Staphylococcus enterotoxin E; shDNA, small hairpin DNA; siRNA, small interfering RNA; WB, Western blot.
7 The online version of this article contains supplemental material.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
