title: Structure-activity relationships of pentamidine-affected ion channel trafficking and dofetilide mediated rescue.
abstract: OBJECTIVE
  Drug interference with normal hERG protein trafficking substantially reduces the channel density in the plasma membrane and thereby poses an arrhythmic threat. The chemical substructures important for hERG trafficking inhibition were investigated using pentamidine as a model drug. Furthermore, the relationship between acute ion channel block and correction of trafficking by dofetilide was studied.
  
  
  METHODS
  hERG and K(IR)2.1 trafficking in HEK293 cells was evaluated by Western blot and immunofluorescence microscopy after treatment with pentamidine and six pentamidine analogues, and correction with dofetilide and four dofetilide analogues that displayed different abilities to inhibit IKr . Molecular dynamics simulations were used to address mode, number and type of interactions between hERG and dofetilide analogues.
  
  
  RESULTS
  Structural modifications of pentamidine differentially affected plasma membrane levels of hERG and K(IR)2.1. Modification of the phenyl ring or substituents directly attached to it had the largest effect, affirming the importance of these chemical residues in ion channel binding. PA-4 had the mildest effects on both ion channels. Dofetilide corrected pentamidine-induced hERG, but not K(IR)2.1 trafficking defects. Dofetilide analogues that displayed high channel affinity, mediated by pi-pi stacks and hydrophobic interactions, also restored hERG protein levels, whereas analogues with low affinity were ineffective.
  
  
  CONCLUSIONS
  Drug-induced trafficking defects can be minimized if certain chemical features are avoided or 'synthesized out'; this could influence the design and development of future drugs. Further analysis of such features in hERG trafficking correctors may facilitate the design of a non-blocking corrector for trafficking defective hERG proteins in both congenital and acquired LQTS.
authors.affiliation: Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Varkevisser
authors.forename: M J C
authors.initials: MJ
authors.lastname: Houtman
authors.forename: T
authors.initials: T
authors.lastname: Linder
authors.forename: K C G
authors.initials: KC
authors.lastname: de Git
authors.forename: H D M
authors.initials: HD
authors.lastname: Beekman
authors.forename: R R
authors.initials: RR
authors.lastname: Tidwell
authors.forename: A P
authors.initials: AP
authors.lastname: Ijzerman
authors.forename: A
authors.initials: A
authors.lastname: Stary-Weinzinger
authors.forename: M A
authors.initials: MA
authors.lastname: Vos
authors.forename: M A G
authors.initials: MA
authors.lastname: van der Heyden
mesh_terms: D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000737:chemistry / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D004285:Dogs; D000072237:ERG1 Potassium Channel; D004705:Endocytosis / Q000187:drug effects; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D049990:Membrane Transport Modulators / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D056004:Molecular Dynamics Simulation; D010419:Pentamidine / Q000009:adverse effects / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D010627:Phenethylamines / Q000737:chemistry / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D051669:Shab Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013449:Sulfonamides / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000889:Anti-Arrhythmia Agents; D000981:Antiprotozoal Agents; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C496990:Kcnb1 protein, mouse; D049990:Membrane Transport Modulators; D010627:Phenethylamines; D026902:Potassium Channel Blockers; D011994:Recombinant Proteins; D051669:Shab Potassium Channels; D013449:Sulfonamides; D010419:Pentamidine; C063533:dofetilide