Identification and functional characterization of KCNQ1 mutations around the exon 7-intron 7 junction affecting the splicing process.
Biochim Biophys Acta
; 1812(11): 1452-9, 2011 Nov.
Article
em En
| MEDLINE
| ID: mdl-21810471
ABSTRACT
BACKGROUND:
KCNQ1 gene encodes the delayed rectifier K(+) channel in cardiac muscle, and its mutations cause long QT syndrome type 1 (LQT1). Especially exercise-related cardiac events predominate in LQT1. We previously reported that a KCNQ1 splicing mutation displays LQT1 phenotypes. METHODS ANDRESULTS:
We identified novel mutation at the third base of intron 7 (IVS7 +3A>G) in exercise-induced LQT1 patients. Minigene assay in COS7 cells and RT-PCR analysis of patients' lymphocytes demonstrated the presence of exon 7-deficient mRNA in IVS7 +3A>G, as well as c.1032G>A, but not in c.1022C>T. Real-time RT-PCR demonstrated that both IVS7 +3A>G and c.1032G>A carrier expressed significant amounts of exon-skipping mRNAs (18.8% and 44.8% of total KCNQ1 mRNA). Current recordings from Xenopus oocytes injected cRNA by simulating its ratios of exon skipping displayed a significant reduction in currents to 64.8 ± 4.5% for IVS7 +3A>G and to 41.4 ± 9.5% for c.1032G>A carrier, respectively, compared to the condition without splicing error. Computer simulation incorporating these quantitative results revealed the pronounced QT prolongation under beta-adrenergic stimulation in IVS7 +3A>G carrier model.CONCLUSION:
Here we report a novel splicing mutation IVS7 +3A>G, identified in a family with mild form LQT1 phenotypes, and examined functional outcome in comparison with three other variants around the exon 7-intron 7 junction. In addition to c.1032G>A mutation, IVS7 +3A>G generates exon-skipping mRNAs, and thereby causing LQT1 phenotype. The severity of clinical phenotypes appeared to differ between the two splicing-related mutations and to result from the amount of resultant mRNAs and their functional consequences.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Síndrome do QT Longo
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Íntrons
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Splicing de RNA
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Éxons
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Canal de Potássio KCNQ1
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Mutação
Tipo de estudo:
Diagnostic_studies
Limite:
Adolescent
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Adult
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Animals
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Female
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Humans
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Male
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Japão