title: Mouse ERG K(+) channel clones reveal differences in protein trafficking and function.
abstract: BACKGROUND
  The mouse ether-a-go-go-related gene 1a (mERG1a, mKCNH2) encodes mERG K(+) channels in mouse cardiomyocytes. The mERG channels and their human analogue, hERG channels, conduct IKr. Mutations in hERG channels reduce IKr to cause congenital long-QT syndrome type 2, mostly by decreasing surface membrane expression of trafficking-deficient channels. Three cDNA sequences were originally reported for mERG channels that differ by 1 to 4 amino acid residues (mERG-London, mERG-Waterston, and mERG-Nie). We characterized these mERG channels to test the postulation that they would differ in their protein trafficking and biophysical function, based on previous findings in long-QT syndrome type 2.
  
  
  RESULTS
  The 3 mERG and hERG channels were expressed in HEK293 cells and neonatal mouse cardiomyocytes and were studied using Western blot and whole-cell patch clamp. We then compared our findings with the recent sequencing results in the Welcome Trust Sanger Institute Mouse Genomes Project (WTSIMGP).
  
  
  CONCLUSIONS
  First, the mERG-London channel with amino acid substitutions in regions of highly ordered structure is trafficking deficient and undergoes temperature-dependent and pharmacological correction of its trafficking deficiency. Second, the voltage dependence of channel gating would be different for the 3 mERG channels. Third, compared with the WTSIMGP data set, the mERG-Nie clone is likely to represent the wild-type mouse sequence and physiology. Fourth, the WTSIMGP analysis suggests that substrain-specific sequence differences in mERG are a common finding in mice. These findings with mERG channels support previous findings with hERG channel structure-function analyses in long-QT syndrome type 2, in which sequence changes in regions of highly ordered structure are likely to result in abnormal protein trafficking.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Eric C
authors.initials: EC
authors.lastname: Lin
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Brooke M
authors.initials: BM
authors.lastname: Moungey
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Evi
authors.initials: E
authors.lastname: Lim
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Concannon
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Corey L
authors.initials: CL
authors.lastname: Anderson
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: John W
authors.initials: JW
authors.lastname: Kyle
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Makielski
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Sadguna Y
authors.initials: SY
authors.lastname: Balijepalli
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (E.C.L., B.M.M., E.L., S.P.C., C.L.A., J.W.K., J.C.M., S.Y.B., C.T.J.).
authors.forename: Craig T
authors.initials: CT
authors.lastname: January
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003001:Cloning, Molecular; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics / Q000378:metabolism*; D020022:Genetic Predisposition to Disease; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating; D008133:Long QT Syndrome / Q000235:genetics / Q000378:metabolism*; D008564:Membrane Potentials; D057507:Mice, 129 Strain; D009154:Mutation; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010641:Phenotype; D021381:Protein Transport; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014162:Transfection
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C000606915:Kcnh2 protein, mouse
keywords: genetic variability; hERG; long‐QT syndrome; mERG; mouse