RESUMO
Congenital long QT syndrome is characterized by a prolongation of ventricular repolarization and recurrent episodes of life-threatening ventricular tachyarrhythmias, often leading to sudden death. We previously identified a missense mutation F275S located within the S5 transmembrane domain of the KCNQ1 ion channel in a Chinese family with long QT syndrome. We used oocyte expression of the KCNQ1 polypeptide to study the effects of the F275S mutation on channel properties. Expression of the F275 mutant, or co-expression with the wild-type S275 polypeptide, significantly decreased channel current amplitudes. Moreover, the F275S substitution decreased the rates of channel activation and deactivation. In transfected HEK293 cells fluorescence microscopy revealed that the F275S mutation perturbed the subcelluar localization of the ion channel. These results indicate that the F275S KCNQ1 mutation leads to impaired polypeptide trafficking that in turn leads to reduction of channel ion currents and altered gating kinetics.
Assuntos
Retículo Endoplasmático/metabolismo , Síndrome do QT Longo/metabolismo , Animais , Linhagem Celular , Humanos , Canal de Potássio KCNQ1/genética , Canal de Potássio KCNQ1/metabolismo , Síndrome do QT Longo/genética , Mutação de Sentido Incorreto , Fenilalanina/genética , Fenilalanina/metabolismo , Transporte Proteico/genética , Serina/genética , Serina/metabolismoRESUMO
OBJECTIVE: To investigate the molecular pathology in families with long QT syndrome (LQTS) including Jervell-Longe-Nielsen syndrome (JLNS) and Romano-ward syndrome (RWS) and Brugada syndrome (BS) in Chinese population. METHODS: Polymerase chain reaction and DNA sequencing were used to screen for KCNQ1, KCNH2, KCNE1, and SCN5A mutation. RESULTS: We identified a novel mutation N1774S in the SCN5A gene of the BS family, a novel mutation G314S in a RWS family which had also been found in Europe, North America, and Japan, and a single nucleotide polymorphisms (SNPs) G643S in the KCNQ1 of the JLNS family. In this JLNS family, another heterozygous novel mutation in exon 2a was found in KCNQ1 of the patients. CONCLUSION: New mutations were found in our experiment, which expand the spectrum of KCNQ1 and SCN5A mutations that cause LQTS and BS.
Assuntos
Síndrome de Jervell-Lange Nielsen/genética , Canal de Potássio KCNQ1/genética , Síndrome do QT Longo/congênito , Síndrome do QT Longo/genética , Mutação , Adolescente , Adulto , Sequência de Bases , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Proteínas Musculares/genética , Canal de Sódio Disparado por Voltagem NAV1.5 , Linhagem , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Síndrome de Romano-Ward/genética , Canais de Sódio/genéticaRESUMO
OBJECTIVE: To identify the mutation of a Chinese family with inherited long QT syndrome(LQTS). METHODS: The disease-causing gene was tentatively determined in light of the clinical manifestations and electrophysiological properties, and then polymerase chain reaction and DNA sequencing were used for screening and identifying mutation. RESULTS: A missense mutation G940A(G314S) in the KCNQ1 gene was identified, which was the 'hot spot' of long QT syndrome mutation. CONCLUSION: The mutation that is involved with long QT syndrome in Chinese patients is the same as that in the European, American and Japanese patients.
Assuntos
Canal de Potássio KCNQ1/genética , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/genética , Mutação de Sentido Incorreto , China , Análise Mutacional de DNA , Saúde da Família , Feminino , Predisposição Genética para Doença/genética , Genótipo , Humanos , Masculino , Linhagem , Reação em Cadeia da PolimeraseRESUMO
To study PCR site-directed mutagenesis of long QT syndrome KCNQ1 gene in vitro. The site-directed mutagenesis of LQTS gene KCNQ1 was made by PCR. Two sets of primers were designed according to the sequence of KCNQ1 cDNA, and mismatch was introduced into primers. Mutagenesis was performed in a three-step PCR. The amplified fragments from the third PCR which contained the mutation site were subcloned into the T-vecor PCR2.1. Then the fragments containing the mutation site was obtained from PCR2.1 with restriction enzyme digestion and was inserted into the same restriction site of pIRES2-EGFP-KCNQ1. With Effectene Transfection Reagent, pIRES(2)-EGFP-KCNQ1 was transfected into HEK293 cell. The sequencing analysis showed that the mutation site was correct. Mutation from T to C in 934 site of KCNQ1 cDNA was found. Under the fluorescence microscope, the green fluorescence was spread in the transfected HEK293 cell, meaning the pIRES(2)-EGFP-KCNQ1 containing the mutation site was expressed correctly.
