Src-like-adaptor protein (SLAP) differentially regulates normal and oncogenic c-Kit signaling

J Cell Sci. 2014 Feb 1;127(Pt 3):653-62. doi: 10.1242/jcs.140590. Epub 2013 Nov 27.

Abstract

The Src-like-adaptor protein (SLAP) is an adaptor protein sharing considerable structural homology with Src. SLAP is expressed in a variety of cells and regulates receptor tyrosine kinase signaling by direct association. In this report, we show that SLAP associates with both wild-type and oncogenic c-Kit (c-Kit-D816V). The association involves the SLAP SH2 domain and receptor phosphotyrosine residues different from those mediating Src interaction. Association of SLAP triggers c-Kit ubiquitylation which, in turn, is followed by receptor degradation. Although SLAP depletion potentiates c-Kit downstream signaling by stabilizing the receptor, it remains non-functional in c-Kit-D816V signaling. Ligand-stimulated c-Kit or c-Kit-D816V did not alter membrane localization of SLAP. Interestingly oncogenic c-Kit-D816V, but not wild-type c-Kit, phosphorylates SLAP on residues Y120, Y258 and Y273. Physical interaction between c-Kit-D816V and SLAP is mandatory for the phosphorylation to take place. Although tyrosine-phosphorylated SLAP does not affect c-Kit-D816V signaling, mutation of these tyrosine sites to phenylalanine can restore SLAP activity. Taken together the data demonstrate that SLAP negatively regulates wild-type c-Kit signaling, but not its oncogenic counterpart, indicating a possible mechanism by which the oncogenic c-Kit bypasses the normal cellular negative feedback control.

Keywords: D816V; Kit; Receptor tyrosine kinase; SLA; Signal transduction; Ubiquitylation; c-Kit-D816V.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Humans
  • Jurkat Cells
  • Phosphorylation
  • Proto-Oncogene Proteins c-kit / biosynthesis*
  • Proto-Oncogene Proteins pp60(c-src) / genetics
  • Proto-Oncogene Proteins pp60(c-src) / metabolism*
  • Signal Transduction / genetics*
  • Stem Cell Factor / genetics
  • Stem Cell Factor / metabolism
  • Ubiquitination
  • src Homology Domains / genetics

Substances

  • Adaptor Proteins, Signal Transducing
  • SLA protein, human
  • Stem Cell Factor
  • Proto-Oncogene Proteins c-kit
  • Proto-Oncogene Proteins pp60(c-src)