title: CFTR Controls the Activity of NF-κB by Enhancing the Degradation of TRADD.
abstract: OBJECTIVE
  Chronic lung infection in cystic fibrosis leads to an inflammatory response that persists because of the chronic presence of bacteria and ultimately leads to a catastrophic failure of lung function.
  
  
  METHODS
  We use a combination of biochemistry, cell and molecular biology to study the interaction of TRADD, a key adaptor molecule in TNFα signaling, with CFTR in the regulation of NFκB.
  
  
  RESULTS
  We show that Wt CFTR binds to and colocalizes with TRADD. TRADD is a key signaling intermediate connecting TNFα with activation of NFκB. By contrast, ΔF508 CFTR does not bind to TRADD. NF-κB activation is higher in CFBE expressing ΔF508 CFTR than in cells expressing Wt CFTR. However, this differential effect is abolished when TRADD levels are knocked down. Transfecting Wt CFTR into CFBE cells reduces NF-κB activity. However the reduction is abolished by the CFTR chloride transport inhibitor-172. Consistently, transfecting in the correctly trafficked CFTR conduction mutants G551D or S341A also fail to reduce NFκB activity. Thus CFTR must be functional if it is to regulate NF-κB activity. We also found that TNFα produced a greater increase in NF-κB activity in CFBE cells than in the same cell when Wt CFTR-corrected. Consistently, the effect is also abolished when TRADD is knocked down by shRNA. Thus, Wt CFTR control of TRADD modulates the physiological activation of NF-κB by TNFα. Based on studies with proteosomal and lysosomal inhibitors, the mechanism by which Wt CFTR, but not ΔF508 CFTR, suppresses TRADD is by lysosomal degradation.
  
  
  CONCLUSIONS
  We have uncovered a novel mechanism whereby Wt CFTR regulates TNFα signaling by enhancing TRADD degradation. Thus by reducing the levels of TRADD, Wt CFTR suppresses downstream proinflammatory NFκB signaling. By contrast, suppression of NF-κB activation fails in CF cells expressing ΔF508 CFTR.
authors.affiliation: Department of Physiology, Medicine, School of Medicine, The Johns Hopkins University, Baltimore, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Liudmila
authors.initials: L
authors.lastname: Cebotaru
authors.forename: Ha Won
authors.initials: HW
authors.lastname: Lee
authors.forename: QingFeng
authors.initials: Q
authors.lastname: Yang
authors.forename: Bette S
authors.initials: BS
authors.lastname: Pollard
authors.forename: Harvey B
authors.initials: HB
authors.lastname: Pollard
authors.forename: William B
authors.initials: WB
authors.lastname: Guggino
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D053199:TNF Receptor-Associated Death Domain Protein / Q000378:metabolism*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C434484:GOPC protein, human; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D016328:NF-kappa B; D053199:TNF Receptor-Associated Death Domain Protein; D014409:Tumor Necrosis Factor-alpha; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator