机构：[1]Department of Cardiology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China[2]Department of Pathology and Laboratory Medicine,University of Rochester Medical Center, Rochester, NY 14642[3]Aab Cardiovascular Research Institute, University of Rochester Medical Center, Rochester, NY 14642[4]Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095-1732, USA[5]Department of Anesthesiology, Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China[6]Department of Pharmacology, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
The human cardiac fast transient outward K+ channel is composed of the K(V)4.3 subunit encoded by KCND3 and the K+ channel-interacting protein 2 (KChIP2) subunit, and determines the early repolarization of the action potential (AP). Two human mutations (G600R and L450F) in K(V)4.3 are associated with Brugada syndrome and they increase the K(V)4.3/KChIP2-encoded fast transient outward K+ current (I-to,I-f) and cause the stable loss of the AP dome. However, the detailed mechanisms underlying the gain of I-to,I-f function by these two mutations are largely unknown. The experiments in the present study were undertaken to investigate the effect of these mutations and the underlying mechanism. Whole cell patch-clamp recording was performed in HEK-293 cells expressing K(V)4.3-wild-type (WT) and K(V)4.3 mutants with KChIP2. The two individual mutant-encoded currents were significantly increased but the kinetics of the channels affected by the two mutations were different. The two mutations slowed K(V)4.3/KChIP2-encoded channel inactivation; they did not increase the recovery from the K(V)4.3/KChIP2-encoded channel inactivation. Western blotting showed that total K(V)4.3 protein was significantly augmented in HEK-293 cells expressing the two individual mutants with KChIP2. Furthermore, immunofluorescence confocal microscopy demonstrated that the K(V)4.3 channel protein was expressed more in the cell membrane compared to the cytoplasm in cells that expressed individual mutants with KChIP2. Also, KChIP2 increased the amount of channel protein in the cell membrane of K(V)4.3 mutants significantly more than K(V)4.3-WT. Reverse transcription-polymerase chain reaction showed that K(V)4.3 mRNA was not significantly changed by individual mutations in the presence of KChIP2. Taken together, the present study revealed that the mutations cause a gain-of-function of K(V)4.3/KChIP2-encoded channels by increasing membrane protein expression and slowing channel inactivation.
基金：
Professor Haodong Xu was supported by a grant from the National Institute of Health (no. K08HL088127), and Dr Faqian Li was supported by a grant from the American Heart Association and the Lawrence J. and Florence A. DeGeorge Charitable Trust (no. 10GRNT4460014).
第一作者机构：[1]Department of Cardiology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China[2]Department of Pathology and Laboratory Medicine,University of Rochester Medical Center, Rochester, NY 14642
共同第一作者：
通讯作者：
通讯机构：[*1]Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, UCLA, 10833 Le Conte Ave, CHS 13-145E Los Angeles, CA 90095-1732, USA
推荐引用方式(GB/T 7714)：
TAO YOU,WEIKE MAO,BENZHI CAI,et al.Two novel Brugada syndrome-associated mutations increase K(V)4.3 membrane expression and function[J].INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE.2015,36(1):309-15.doi:10.3892/ijmm.2015.2223.
APA：
TAO YOU,WEIKE MAO,BENZHI CAI,FAQIAN LI&HAODONG XU.(2015).Two novel Brugada syndrome-associated mutations increase K(V)4.3 membrane expression and function.INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE,36,(1)
MLA：
TAO YOU,et al."Two novel Brugada syndrome-associated mutations increase K(V)4.3 membrane expression and function".INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 36..1(2015):309-15
