αvβ3-integrin-mediated adhesion is regulated through an AAK1L- and EHD3-dependent rapid-recycling pathway

Protein transport through the endosome is critical for maintaining proper integrin cell surface integrin distribution to support cell adhesion, motility and viability. Here we employ a live-cell imaging approach to evaluate the relationship between integrin function and transport through the early endosome. We discovered that two early endosome factors, AAK1L and EHD3, are critical for αvβ3-integrin-mediated cell adhesion in HeLa cells. siRNA-mediated depletion of either factor delays short-loop b3 integrin recycling from the early endosome back to the cell surface. Total internal reflection fluorescence-based colocalization analysis reveals that β3 integrin transits AAK1L- and EHD3-positive endosomes near the cell surface, a subcellular location consistent with a rapid-recycling role for both factors. Moreover, structure-function analysis reveals that AAK1L kinase activity, as well as its C-terminal domain, is essential for cell adhesion maintenance. Taken together, these data reveal an important role for AAK1L and EHD3 in maintaining cell viability and adhesion by promoting αvβ3 integrin rapid recycling from the early endosome.