Disabled-2 Protein Facilitates Assembly Polypeptide-2-independent Recruitment of Cystic Fibrosis Transmembrane Conductance Regulator to Endocytic Vesicles in Polarized Human Airway Epithelial Cells

• Published in: The Journal of biological chemistry 2012-04, Vol.287 (18), p.15087-15099
• Main Authors: Cihil, Kristine M., Ellinger, Philipp, Fellows, Abigail, Stolz, Donna Beer, Madden, Dean R., Swiatecka-Urban, Agnieszka
• Format: Article
• Language: English
• Subjects: ABC Transporter; Adaptor Protein Complex 2 - genetics; Adaptor Protein Complex 2 - metabolism; Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Amino Acid Motifs; AP-2; Apoptosis Regulatory Proteins; Cell Biology; Cell Line; Cell Membrane - genetics; Cell Membrane - metabolism; Cell Polarity - physiology; CFTR; CLASP; Clathrin - genetics; Clathrin - metabolism; Clathrin-coated Vesicles; Cystic Fibrosis Transmembrane Conductance Regulator - genetics; Cystic Fibrosis Transmembrane Conductance Regulator - metabolism; Dab2; Endocytosis; Endocytosis - physiology; Epithelial Cell; Epithelial Cells - cytology; Epithelial Cells - metabolism; Human Airway Epithelial Cells; Humans; Membrane Trafficking; Protein Stability; Protein Structure, Tertiary; Respiratory Mucosa - cytology; Respiratory Mucosa - metabolism; Transport Vesicles - genetics; Transport Vesicles - metabolism; Tumor Suppressor Proteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.341875

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated Cl− channel expressed in the apical plasma membrane of fluid-transporting epithelia, where the plasma membrane abundance of CFTR is in part controlled by clathrin-mediated endocytosis. The protein networks that control CFTR endocytosis in epithelial cells have only been partially explored. The assembly polypeptide-2 complex (AP-2) is the prototypical endocytic adaptor critical for optimal clathrin coat formation. AP-2 is essential for recruitment of cargo proteins bearing the YXXΦ motif. Although AP-2 interacts directly with CFTR in vitro and facilitates CFTR endocytosis in some cell types, it remains unknown whether it is critical for CFTR uptake into clathrin-coated vesicles (CCVs). Disabled-2 (Dab2) is a clathrin-associated sorting protein (CLASP) that contributes to clathrin recruitment, vesicle formation, and cargo selection. In intestinal epithelial cells Dab2 was not found to play a direct role in CFTR endocytosis. By contrast, AP-2 and Dab2 were shown to facilitate CFTR endocytosis in human airway epithelial cells, although the specific mechanism remains unknown. Our data demonstrate that Dab2 mediates AP-2 independent recruitment of CFTR to CCVs in polarized human airway epithelial cells. As a result, it facilitates CFTR endocytosis and reduces CFTR abundance and stability in the plasma membrane. These effects are mediated by the DAB homology domain. Moreover, we show that in human airway epithelial cells AP-2 is not essential for CFTR recruitment to CCVs. Background: The proteins that control CFTR endocytosis in epithelial cells have only been partially explored. Results: In human airway epithelial cells Disabled-2 mediates recruitment of CFTR to clathrin-coated vesicles (CCVs) independent of the assembly polypeptide-2 (AP-2). Conclusion: AP-2 is not essential for CFTR recruitment to CCVs in these cells. Significance: Regulating CFTR interaction with Dab2 may stabilize CFTR in the plasma membrane.