c-kit receptor signaling through its phosphatidylinositide-3'-kinase- binding site and protein kinase C: Role in mast cell enhancement of degranulation, adhesion, and membrane ruffling

Keith Vosseller, Gregory Stella, Nelson S. Yee, Peter Besmer

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91 Scopus citations

Abstract

In bone marrow-derived mast cells (BMMCs), the Kit receptor tyrosine kinase mediates diverse responses including proliferation, survival, chemotaxis, migration, differentiation, and adhesion to extracellular matrix. In connective tissue mast cells, a role for Kit in the secretion of inflammatory mediators has been demonstrated as well. We recently demonstrated a role for phosphatidylinositide-3' (PI 3)-kinase in Kit-ligand (KL)-induced adhesion of BMMCs to fibronectin. Herein, we investigated the mechanism by which Kit mediates enhancement of FcεRI-mediated degranulation, cytoskeletal rearrangements, and adhesion in BMMCs. W(sh)/W(sh) BMMCs, lacking endogenous Kit expression, were transduced to express normal and mutant Kit receptors containing Tyr → Phe substitutions at residues 719 and 821. Although the normal Kit receptor fully restored KL-induced responses in W(sh)/W(sh) BMMCs, Kit(Y719F), which fails to bind and activate PI 3-kinase, failed to potentiate degranulation and is impaired in mediating membrane ruffling and actin assembly. Inhibition of PI 3-kinase with wortmannin or LY294002 also inhibited secretory enhancement and cytoskeletal rearrangements mediated by Kit. In contrast, secretory enhancement and adhesion stimulated directly through protein kinase C (PKC) do not require PI 3-kinase. Calphostin C, an inhibitor of PKC, blocked Kit-mediated adhesion to fibronectin, secretory enhancement, membrane ruffling, and filamentous actin assembly. Although cytochalasin D inhibited Kit-mediated filamentous actin assembly and membrane ruffling, secretory enhancement and adhesion to fibronectin were not affected by this drug. Therefore, Kit-mediated cytoskeletal rearrangements that are dependent on actin polymerization can be uncoupled from the Kit-mediated secretory and adhesive responses. Our results implicate receptor-proximal PI 3-kinase activation and activation of a PKC isoform in Kit-mediated secretory enhancement, adhesion, and cytoskeletal reorganization.

Original languageEnglish (US)
Pages (from-to)909-922
Number of pages14
JournalMolecular biology of the cell
Volume8
Issue number5
DOIs
StatePublished - May 1997

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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