GGA2 interacts with EGFR cytoplasmic domain to stabilize the receptor expression and promote cell growth

Sci Rep. 2018 Jan 22;8(1):1368. doi: 10.1038/s41598-018-19542-4.

Abstract

Epidermal growth factor receptor (EGFR) signaling and its downregulation upon ligand binding have been extensively documented. However, the mechanisms by which cells maintain steady-state EGFR expression remain poorly understood. Here, we report a novel role of Golgi-localized, γ-adaptin ear-containing, ADP ribosylation factor-binding protein 2 (GGA2) in the control of EGFR turnover. Whereas GGA1- or GGA3-depletion increased EGFR expression, GGA2-depletion by RNAi greatly reduced steady-state expression of EGFR, reflecting enhanced lysosomal degradation of EGFR. Subsequent pull-down assays showed interactions of VHS-GAT domains from three GGAs with the cytoplasmic juxtamembrane region (jxt) of EGFR, which was dependent on N108 in the VHS domain. Proximity ligation assay also revealed the steady-state interaction between GGA2 and EGFR in situ. Moreover, reduced expression of EGFR in GGA2-depleted cells was reversed by additional depletion of GGA1 or GGA3, suggesting that GGA1 and GGA3 promote EGFR degradation. In addition, GGA2-depleted cells had reduced EGF signaling and cell proliferation in cell culture and xenograft experiments. Finally, GGA2 was upregulated in 30.8% of human hepatocellular carcinomas and 23.3% of colorectal cancers. Together, these results indicate that GGA2 supports cell growth by interacting with EGFR for sustaining the receptor expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Animals
  • Binding Sites
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Cell Proliferation
  • Colorectal Neoplasms / chemistry
  • Colorectal Neoplasms / metabolism*
  • ErbB Receptors / chemistry
  • ErbB Receptors / metabolism
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology
  • Lysosomes / metabolism
  • Mice
  • Neoplasm Transplantation
  • Protein Binding
  • Proteolysis
  • Signal Transduction
  • Up-Regulation

Substances

  • Adaptor Proteins, Vesicular Transport
  • GGA2 protein, human
  • EGFR protein, human
  • ErbB Receptors