Electrophysiological characterization of three non-synonymous single nucleotide polymorphisms (R87Q, A251T, and P307S) found in hKv1.5.
Non-synonymous single nucleotide polymorphisms (SNPs) in the KCNA5/hKv1.5 gene, which encodes for a voltage-gated K+ channel responsible for the I (Kur) current in the human atria, have been recently reported. To gain further knowledge on potential influence of hKv1.5 SNPs, we searched for their presence in a specific population of 96 French-Canadians and characterized electrophysiological properties of the variants in two cell lines. The presumed promoter (-83 bp) and coding regions were sequenced. We found three heterozygous SNPs: R87Q, A251T, and P307S. Functional analysis of SNPs transfected in Chinese hamster ovary (CHO) cells showed that both R87Q and P307S diminished the inactivation amplitude (e.g., at +60 mV, amplitudes were 89+/-26, 23+/-4, and 22+/-7 pA/pF for the wild type, R87Q and P307S, respectively; n=8, 6, and 8, respectively). Inactivation was slowed with these variants (e.g., tau (fast) at +50 mV were 270+/-48, 490+/-66, and 340+/-45 ms for the wild type, R87Q, and P307S, respectively) while R87Q additionally accelerated the rate of hKv1.5 channel opening. A dominant-negative effect was observed for R87Q but not for P307S. SNPs properties were not reproduced when expressed in the HEK293 cell line, suggesting that the regulatory beta-subunit present in CHO cells (and the human heart) is essential for the SNPs effects that we have observed.
Plante
Isabelle
I
Quebec Heart Institute, Laval Hospital Research Centre, and Faculty of Pharmacy, Laval University, Sainte-Foy, Quebec, G1V 4G5, Canada.
Fournier
Dominique
D
Ricard
Guylaine
G
Drolet
Benoît
B
O'Hara
Gilles
G
Champagne
Jean
J
Mathieu
Patrick
P
Baillot
Richard
R
Daleau
Pascal
P
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004594:Electrophysiology; D015870:Gene Expression; D006801:Humans; D051666:Kv1.5 Potassium Channel / Q000235:genetics / Q000502:physiology*; D018408:Patch-Clamp Techniques; D020641:Polymorphism, Single Nucleotide; D011792:Quebec; D017422:Sequence Analysis, DNA
C496981:KCNA5 protein, human; D051666:Kv1.5 Potassium Channel