Signal transduction by the α6β4 integrin: Distinct β4 subunit sites mediate recruitment of Shc/Grb2 and association with the cytoskeleton of hemidesmosomes

Fabrizio Mainiero, Angela Pepe, Kishore K. Wary, Laura Spinardi, Moosa Mohammadi, Joseph Schlessinger, Filippo G. Giancotti

Research output: Contribution to journalArticlepeer-review

Abstract

We have examined the mechanism of signal transduction by the hemidesmosomal integrin α6β4, a laminin receptor involved in morphogenesis and tumor progression. Immunoprecipitation and immune complex kinase assays indicated that antibody- or laminin-induced ligation of α6β4 causes tyrosine phosphorylation of the β4 subunit in intact cells and that this event is mediated by a protein kinase(s) physically associated with the integrin. Co-immunoprecipitation and GST fusion protein binding experiments showed that the adaptor protein She forms a complex with the tyrosine-phosphorylated β4 subunit. She is then phosphorylated on tyrosine residues and recruits the adaptor Grb2, thereby potentially linking α6β4 to the ras pathway. The β4 subunit was found to be phosphorylated at multiple tyrosine residues in vivo, including a tyrosine-based activation motif (TAM) resembling those found in T and B cell receptors. Phenylalanine substitutions at the β4 TAM disrupted association of α6β4 with hemidesmosomes, but did not interfere with tyrosine phosphorylation of She and recruitment of Grb2. These results indicate that signal transduction by the α6β4 integrin is mediated by an associated tyrosine kinase and that phosphorylation of distinct sites in the β4 tail mediates assembly of the hemidesmosomal cytoskeleton and recruitment of Shc/Grb2.

Original languageEnglish
Pages (from-to)4470-4481
Number of pages12
JournalEMBO Journal
Volume14
Issue number18
Publication statusPublished - 1995

Keywords

  • Hemidesmosomes
  • Integrins
  • She
  • Signaling
  • Tyrosine phosphorylation

ASJC Scopus subject areas

  • Cell Biology
  • Genetics

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