title: Roscovitine is a proteostasis regulator that corrects the trafficking defect of F508del-CFTR by a CDK-independent mechanism.
abstract: OBJECTIVE
  The most common mutation in cystic fibrosis (CF), F508del, causes defects in trafficking, channel gating and endocytosis of the CF transmembrane conductance regulator (CFTR) protein. Because CF is an orphan disease, therapeutic strategies aimed at improving mutant CFTR functions are needed to target the root cause of CF.
  
  
  METHODS
  Human CF airway epithelial cells were treated with roscovitine 100 μM for 2 h before CFTR maturation, expression and activity were examined. The mechanism of action of roscovitine was explored by recording the effect of depleting endoplasmic reticulum (ER) Ca(2+) on the F508del-CFTR/calnexin interaction and by measuring proteasome activity.
  
  
  RESULTS
  Of the cyclin-dependent kinase (CDK) inhibitors investigated, roscovitine was found to restore the cell surface expression and defective channel function of F508del-CFTR in human CF airway epithelial cells. Neither olomoucine nor (S)-CR8, two very efficient CDK inhibitors, corrected F508del-CFTR trafficking demonstrating that the correcting effect of roscovitine was independent of CDK inhibition. Competition studies with inhibitors of the ER quality control (ERQC) indicated that roscovitine acts on the calnexin pathway and on the degradation machinery. Roscovitine was shown (i) to partially inhibit the interaction between F508del-CFTR and calnexin by depleting ER Ca(2+) and (ii) to directly inhibit the proteasome activity in a Ca(2+) -independent manner.
  
  
  CONCLUSIONS
  Roscovitine is able to correct the defective function of F508del-CFTR by preventing the ability of the ERQC to interact with and degrade F508del-CFTR via two synergistic but CDK-independent mechanisms. Roscovitine has potential as a pharmacological therapy for CF.
authors: Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, Poitiers, France.
authors: C
authors: C
authors: Norez
authors: C
authors: C
authors: Vandebrouck
authors: J
authors: J
authors: Bertrand
authors: S
authors: S
authors: Noel
authors: E
authors: E
authors: Durieu
authors: N
authors: N
authors: Oumata
authors: H
authors: H
authors: Galons
authors: F
authors: F
authors: Antigny
authors: A
authors: A
authors: Chatelier
authors: P
authors: P
authors: Bois
authors: L
authors: L
authors: Meijer
authors: F
authors: F
authors: Becq
mesh_terms: D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004847:Epithelial Cells; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D011687:Purines / Q000494:pharmacology*; D000077546:Roscovitine
chemical_list: D062554:NAV1.5 Voltage-Gated Sodium Channel; D047428:Protein Kinase Inhibitors; D011687:Purines; C568320:SCN5A protein, human; D000077546:Roscovitine; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D018844:Cyclin-Dependent Kinases; D046988:Proteasome Endopeptidase Complex; D002118:Calcium