PX-RICS mediates ER-to-Golgi transport of the N-cadherin/beta-catenin complex

Nakamura T, Hayashi T, Nasu-Nishimura Y, Sakaue F, Morishita Y, Okabe T, Ohwada S, Matsuura K, Akiyama T
Source: Genes Dev
Publication Date: (2008)
Issue: 22(9): 1244-56
Research Area:
Cancer Research/Cell Biology
Dermatology/Tissue Engineering
Cells used in publication:
Embryonic fibroblast, mouse (MEF) immort
Species: mouse
Tissue Origin: embryo
Nucleofector® I/II/2b
Cadherins mediate Ca(2+)-dependent cell-cell adhesion. Efficient export of cadherins from the endoplasmic reticulum (ER) is known to require complex formation with beta-catenin. However, the molecular mechanisms underlying this requirement remain elusive. Here we show that PX-RICS, a beta-catenin-interacting GTPase-activating protein (GAP) for Cdc42, mediates ER-to-Golgi transport of the N-cadherin/beta-catenin complex. Knockdown of PX-RICS expression induced the accumulation of the N-cadherin/beta-catenin complex in the ER and ER exit site, resulting in a decrease in cell-cell adhesion. PX-RICS was also required for ER-to-Golgi transport of the fibroblast growth factor-receptor 4 (FGFR4) associated with N-cadherin. PX-RICS-mediated ER-to-Golgi transport was dependent on its interaction with beta-catenin, phosphatidylinositol-4-phosphate (PI4P), Cdc42, and its novel binding partner gamma-aminobutyric acid type A receptor-associated protein (GABARAP). These results suggest that PX-RICS ensures the efficient entry of the N-cadherin/beta-catenin complex into the secretory pathway, and thereby regulates the amount of N-cadherin available for cell adhesion and FGFR4-mediated signaling.