title: Disabled-2 protein facilitates assembly polypeptide-2-independent recruitment of cystic fibrosis transmembrane conductance regulator to endocytic vesicles in polarized human airway epithelial cells.
abstract: 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.
authors.affiliation: Department of Nephrology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15224, USA.
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Cihil
authors.forename: Philipp
authors.initials: P
authors.lastname: Ellinger
authors.forename: Abigail
authors.initials: A
authors.lastname: Fellows
authors.forename: Donna Beer
authors.initials: DB
authors.lastname: Stolz
authors.forename: Dean R
authors.initials: DR
authors.lastname: Madden
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Swiatecka-Urban
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D051017:Apoptosis Regulatory Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology*; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D022161:Transport Vesicles / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
chemical_list: D033962:Adaptor Protein Complex 2; D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C505032:CFTR protein, human; D002966:Clathrin; C102885:DAB2 protein, human; D025521:Tumor Suppressor Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator