Localization of phospho-β-dystroglycan (pY892) to an intracellular vesicular compartment in cultured cells and skeletal muscle fibers in vivo

Federica Sotgia, Gloria Bonuccelli, Mark Bedford, Andrea Brancaccio, Ulrike Mayer, Mark T. Wilson, Roberto Campos-Gonzalez, James W. Brooks, Marius Sudol, Michael P. Lisanti

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

β-Dystroglycan is a ubiquitously expressed integral membrane protein that undergoes tyrosine phosphorylation in an adhesion-dependent manner. Tyrosine 892 is now thought to be the principal site for recognition by the c-Src tyrosine kinase; however, little is known about the regulation of this phosphorylation event in vivo. Here, we generated a novel monoclonal antibody probe that recognizes only tyrosine 892 phosphorylated β-dystroglycan (pY892). We show that upon tyrosine phosphorylation, β-dystroglycan undergoes a profound change in its sub-cellular localization (e.g., from the plasma membrane to an internal membrane compartment). One possibility is that the net negative charge at position 892 causes the redistribution of β-dystroglycan to this intracellular vesicular location. In support of this notion, mutation of tyrosine 892 to glutamate (Y892E) is sufficient to drive this intracellular localization, while other point mutants (Y892F and Y892A) remain at the plasma membrane. Interestingly, our colocalization studies with endosomal markers (EEA1, transferrin, and transferrin receptor) suggest that these phosphoβ-dystroglycan containing internal vesicles represent a subset of recycling endosomes. At the level of these internal vesicular structures, we find that tyrosine phosphorylated β-dystroglycan is colocalized with c-Src. In addition, we demonstrate that known ligands for α-dystroglycan, namely, agrin and laminin, are able to induce the tyrosine phosphorylation of β-dystroglycan. Finally, we show that tyrosine phosphorylated β-dystroglycan is also detectable in skeletal muscle tissue lysates and is localized to an internal vesicular membrane compartment in skeletal muscle fibers in vivo. The generation of a phosphospecific β-dystroglycan (pY892) mAb probe provides a new powerful tool for dissecting the role of dystroglycan phosphorylation in normal cellular functioning and in the pathogenesis of muscular dystrophies.

Original languageEnglish
Pages (from-to)7110-7123
Number of pages14
JournalBiochemistry
Volume42
Issue number23
DOIs
StatePublished - 17 Jun 2003

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