title: Direct interaction with filamins modulates the stability and plasma membrane expression of CFTR.
abstract: The role of the cystic fibrosis transmembrane conductance regulator (CFTR) as a cAMP-dependent chloride channel on the apical membrane of epithelia is well established. However, the processes by which CFTR is regulated on the cell surface are not clear. Here we report the identification of a protein-protein interaction between CFTR and the cytoskeletal filamin proteins. Using proteomic approaches, we identified filamins as proteins that associate with the extreme CFTR N terminus. Furthermore, we identified a disease-causing missense mutation in CFTR, serine 13 to phenylalanine (S13F), which disrupted this interaction. In cells, filamins tethered plasma membrane CFTR to the underlying actin network. This interaction stabilized CFTR at the cell surface and regulated the plasma membrane dynamics and confinement of the channel. In the absence of filamin binding, CFTR was internalized from the cell surface, where it prematurely accumulated in lysosomes and was ultimately degraded. Our data demonstrate what we believe to be a previously unrecognized role for the CFTR N terminus in the regulation of the plasma membrane stability and metabolic stability of CFTR. In addition, we elucidate the molecular defect associated with the S13F mutation.
authors.affiliation: Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Thelin
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.forename: Martina
authors.initials: M
authors.lastname: Gentzsch
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Kreda
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Sallee
authors.forename: Cameron O
authors.initials: CO
authors.lastname: Scarlett
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Borchers
authors.forename: Ken
authors.initials: K
authors.lastname: Jacobson
authors.forename: M Jackson
authors.initials: MJ
authors.lastname: Stutts
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Milgram
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003285:Contractile Proteins / Q000378:metabolism*; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004355:Drug Stability; D064448:Filamins; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008840:Microfilament Proteins / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011485:Protein Binding; D011487:Protein Conformation; D040901:Proteomics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: C505032:CFTR protein, human; D003285:Contractile Proteins; D064448:Filamins; D008840:Microfilament Proteins; D011994:Recombinant Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator