EGF induces macropinocytosis and SNX1-modulated recycling of E-cadherin

David M Bryant,Shannon R Joseph,Jennifer L Stow,Markus C Kerr,Keith E Mostov,Rohan D Teasdale,Luke A Hammond

doi:10.1242/jcs.000653

David M Bryant, Shannon R Joseph + Show 5 more

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https://doi.org/10.1242/jcs.000653

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Abstract

In epithelia, junction proteins are endocytosed for modulation of cell-cell adhesion and cell polarity. In response to growth factors, the cell-cell adhesion protein E-cadherin is internalized from the cell surface with degradation or recycling as potential fates. However, the cellular machinery involved in cadherin internalization and recycling remains controversial. Here we investigated EGF-induced E-cadherin internalization. EGF stimulation of MCF-7 cells resulted in Rac1-modulated macropinocytosis of the E-cadherin-catenin complex into endosomal compartments that colocalized with EEA1 and the sorting nexin, SNX1. Depletion of cellular SNX1 levels by siRNA resulted in increased intracellular accumulation and turnover of E-cadherin internalized from the cell surface in response to EGF. Moreover, SNX1 was also required for efficient recycling of internalized E-cadherin and re-establishment of epithelial adhesion. Together, these findings demonstrate a role for SNX1 in retrieval of E-cadherin from a degradative endosomal pathway and in membrane trafficking pathways that regulate E-cadherin recycling.

Highlights

For epithelial cells in sheets or tubes, alteration of stable cellcell adhesion facilitates morphological remodeling events, such as migration during development or in metastasis during cancer (Gumbiner, 2005; Thiery, 2002)
In canine kidney epithelial cells, the adhesion protein Ecadherin undergoes constitutive endocytosis and recycling, and it is internalized in response to hepatocyte growth factor (HGF) for modulation of cell-cell adhesion (Fujita et al, 2002; Le et al, 1999)
As reformation of cell-cell contacts in this assay requires recycling of internalized Ecadherin back to the cell surface, these findings reveal that SNX1 is required for efficient recycling of membrane containing internalized E-cadherin

Summary

Introduction

For epithelial cells in sheets or tubes, alteration of stable cellcell adhesion facilitates morphological remodeling events, such as migration during development or in metastasis during cancer (Gumbiner, 2005; Thiery, 2002). Internalization of junction proteins is one mechanism for temporary or permanent modulation of cell-cell adhesion (reviewed in Bryant and Stow, 2004; D’Souza-Schorey, 2005; Ivanov et al, 2005). In canine kidney epithelial cells, the adhesion protein Ecadherin undergoes constitutive endocytosis and recycling, and it is internalized in response to hepatocyte growth factor (HGF) for modulation of cell-cell adhesion (Fujita et al, 2002; Le et al, 1999). The cytoplasmic domain of E-cadherin supports interactions with multiple binding partners, most notably the catenin proteins, ␤-catenin or ␥-catenin (plakoglobin), and p120ctn (Yap, 1998). In mammalian cells, binding of p120ctn to the juxtamembrane cytoplasmic region of E-cadherin delimits cadherin endocytosis and turnover, thereby stabilizing cadherin-based adhesion (Davis et al, 2003; Xiao et al, 2003; Yap et al, 1998)

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