title: Dynamic regulation of cystic fibrosis transmembrane conductance regulator by competitive interactions of molecular adaptors.
abstract: Disorganized ion transport caused by hypo- or hyperfunctioning of the cystic fibrosis transmembrane conductance regulator (CFTR) can be detrimental and may result in life-threatening diseases such as cystic fibrosis or secretory diarrhea. Thus, CFTR is controlled by elaborate positive and negative regulations for an efficient homeostasis. It has been shown that expression and activity of CFTR can be regulated either positively or negatively by PDZ (PSD-95/discs large/ZO-1) domain-based adaptors. Although a positive regulation by PDZ domain-based adaptors such as EBP50/NHERF1 is established, the mechanisms for negative regulation of the CFTR by Shank2, as well as the effects of multiple adaptor interactions, are not known. Here we demonstrate a physical and physiological competition between EBP50-CFTR and Shank2-CFTR associations and the dynamic regulation of CFTR activity by these positive and negative interactions using the surface plasmon resonance assays and consecutive patch clamp experiments. Furthermore whereas EBP50 recruits a cAMP-dependent protein kinase (PKA) complex to CFTR, Shank2 was found to be physically and functionally associated with the cyclic nucleotide phosphodiesterase PDE4D that precludes cAMP/PKA signals in epithelial cells and mouse brains. These findings strongly suggest that balanced interactions between the membrane transporter and multiple PDZ-based adaptors play a critical role in the homeostatic regulation of epithelial transport and possibly the membrane transport in other tissues.
authors.affiliation: Department of Pharmacology, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Wito
authors.initials: W
authors.lastname: Richter
authors.forename: Wan
authors.initials: W
authors.lastname: Namkung
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Kim
authors.forename: Eunjoon
authors.initials: E
authors.lastname: Kim
authors.forename: Marco
authors.initials: M
authors.lastname: Conti
authors.forename: Min Goo
authors.initials: MG
authors.lastname: Lee
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D003550:Cystic Fibrosis / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D003967:Diarrhea / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D051528:Guanylate Kinases; D006706:Homeostasis / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D017136:Ion Transport / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; C488222:Shank2 protein, mouse; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D051528:Guanylate Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4