Heteromerization of Kir2.x Potassium Channels Contributes to the Phenotype of Andersen's Syndrome

Andersen's syndrome, an autosomal dominant disorder related to mutations of the potassium channel Kir2.1, is characterized by cardiac arrhythmias, periodic paralysis, and dysmorphic bone structure. The aim of our study was to find out whether heteromerization of Kir2.1 channels with wild-type K...

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Published in:Proceedings of the National Academy of Sciences - PNAS 2002-05, Vol.99 (11), p.7774-7779
Main Authors: Preisig-Müller, Regina, Schlichthörl, Günter, Goerge, Tobias, Heinen, Steffen, Brüggemann, Andrea, Rajan, Sindhu, Derst, Christian, Veh, Rüdiger W., Daut, Jürgen
Format: Article
Language:English
Subjects:
Amino Acid Substitution
Amino acids
Anatomy & physiology
Andersen syndrome
Andersen's syndrome
Animals
Biological Sciences
Cell Line
Complementary RNA
Guinea Pigs
HEK293 cells
Humans
Inhibitory concentration 50
Kir2.1 protein
Kir2.2 protein
Kir2.3 protein
Long QT Syndrome - genetics
Medical disorders
Models, Molecular
Mutagenesis, Insertional
Mutation
Myocardium
Oocytes
Paralyses, Familial Periodic - genetics
Phenotype
Phenotypes
Potassium
Potassium Channels, Inwardly Rectifying - chemistry
Potassium Channels, Inwardly Rectifying - genetics
Protein Conformation
Protein Subunits
Rectifiers
Transfection
Xenopus
Yeasts
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Summary:Andersen's syndrome, an autosomal dominant disorder related to mutations of the potassium channel Kir2.1, is characterized by cardiac arrhythmias, periodic paralysis, and dysmorphic bone structure. The aim of our study was to find out whether heteromerization of Kir2.1 channels with wild-type Kir2.2 and Kir2.3 channels contributes to the phenotype of Andersen's syndrome. The following results show that Kir2.x channels can form functional heteromers: (i) HEK293 cells transfected with Kir2.x-Kir2.y concatemers expressed inwardly rectifying K+channels with a conductance of 28-30 pS. (ii) Expression of Kir2.x-Kir2.y concatemers in Xenopus oocytes produced inwardly rectifying, Ba2+sensitive currents. (iii) When Kir2.1 and Kir2.2 channels were coexpressed in Xenopus oocytes the IC50for Ba2+block of the inward rectifier current differed substantially from the value expected for independent expression of homomeric channels. (iv) Coexpression of nonfunctional Kir2.x constructs, in which the GYG region of the pore region was replaced by AAA, with wild-type Kir2.x channels produced both homomeric and heteromeric dominant-negative effects. (v) Kir2.1 and Kir2.3 channels could be coimmunoprecipitated in membrane extracts from isolated guinea pig cardiomyocytes. (vi) Yeast two-hybrid analysis showed interaction between the N- and C-terminal intracellular domains of different Kir2.x subunits. Coexpression of Kir2.1 mutants related to Andersen's syndrome with wild-type Kir2.x channels showed a dominant negative effect, the extent of which varied between different mutants. Our results suggest that differential tetramerization of the mutant allele of Kir2.1 with wild-type Kir2.1, Kir2.2, and Kir2.3 channels represents the molecular basis of the extraordinary pleiotropy of Andersen's syndrome.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.102609499