SH3 Domain-mediated Interaction of Dystroglycan and Grb2

doi:10.1074/jbc.270.20.11711

SH3 Domain-mediated Interaction of Dystroglycan and Grb2(*)

From the (1) Howard Hughes Medical Institute,
(2) Department of Physiology and Biophysics, and
(3) Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242

^¶Investigator of the Howard Hughes Medical Institute. To whom correspondence should be addressed:
Howard Hughes Medical Inst., University of Iowa College of Medicine, 400 EMRB, Iowa City, IA 52242.
Tel.: 319-335-7867; Fax: 319-335-6957; E-mail: kevin-campbell{at}uiowa.edu.

Abstract

Dystroglycan is a novel laminin receptor that links the extracellular matrix and sarcolemma in skeletal muscle. The dystroglycan complex containing α- and β-dystroglycan also serves as an agrin receptor in muscle, where it may regulate agrin-induced acetylcholine receptor clustering at the neuromuscular junction. β-Dystroglycan has now been expressed in vitro and shown to directly interact with Grb2, an adapter protein involved in signal transduction and cytoskeletal organization. Protein binding assays with two Grb2 mutants, Grb2/P49L and Grb2/G203R, which correspond to the loss-of-function mutants in the Caenorhabditis elegans sem -5, demonstrated that the dystroglycan-Grb2 association is through β-dystroglycan C-terminal proline-rich domains and Grb2 Src homology 3 domains. Affinity chromatography has also shown endogenous skeletal muscle Grb2 interacts with β-dystroglycan. Immunoprecipitation experiments have demonstrated that Grb2 associates with α/β-dystroglycan in vivo in both skeletal muscle and brain. The specific dystroglycan-Grb2 interaction may play an important role in extracellular matrix-mediated signal transduction and/or cytoskeleton organization in skeletal muscle that may be essential for muscle cell viability.

Footnotes

↵^§ Supported by an American Heart Association Iowa Affiliate fellowship.
↵* This work was supported in part by the Muscular Dystrophy Association. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹M. Durbeej, E. Larsson, O. Ibraghimov-Beskrovnaya, S. L. Roberds, K. P. Campbell, and P. Ekblom, unpublished data.
↵² The abbreviations used are:

SH2 and −3

Src homology 2 and 3

GST

glutathione S-transferase

PCR

polymerase chain reaction

PAGE

polyacrylamide gel electrophoresis

CHAPS

3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid.