The cytoplasmic adaptor protein X11 alpha and extracellular matrix protein Reelin regulate ApoE receptor 2 trafficking and cell movement

The goal of this study was to determine the effect of X11 alpha on ApoE receptor 2 (ApoEr2) trafficking and the functional significance of this interaction on cell movement in MCF 10A epithelial cells. We found that X11 alpha increased surface levels of ApoEr2 by 64% compared to vector control, as determined by surface protein biotinylation. To examine the functional significance of this effect, we tested whether ApoEr2 played a novel role in cell movement in a wound-healing assay. We found that overexpression of ApoEr2 in MCF 10A cells increased cell migration velocity by 87% (P<0.01, n = 4) compared to GFP control. Cotransfection of X11 alpha had an additive effect on average velocity compared to ApoEr2 alone (13%; P<0.05, n = 4). In addition, we tested whether ApoEr2 ligands altered the effect of ApoEr2 on cell movement. We found that treatment with concentrated medium containing the extracellular matrix protein Reelin, but not control medium, further increased the velocity of ApoEr2-but not APP-transfected cells (20%; P<0.001, n = 4). Similarly, Reelin treatment increased cell velocity on the presence of ApoEr2 and X11 alpha (10%; P<0.05, n = 4). In the present study, we are the first to demonstrate that ApoEr2 regulates cell movement, and both X11 alpha and Reelin enhance this effect.-Minami, S. S., Sung, Y. M., Dumanis, S. B., Chi, S. H., Burns, M. P., Ann, E.-J., Suzuki, T., Turner, R. S., Park, H.-S., Pak, D. T. S., Rebeck, G. W., Hoe, H.- S. The cytoplasmic adaptor protein X11 alpha and extracellular matrix protein Reelin regulate ApoE receptor 2 trafficking and cell movement. FASEB J. 24, 58-69 ( 2010). www.fasebj.org