Mutation in Nuclear Pore Component NUP155 Leads to Atrial Fibrillation and Early Sudden Cardiac Death

Journal of Biological Chemistry

Liu

et al. 2016

Self Cite

Na v 1.5, the pore-forming ␣ subunit of the cardiac voltagegated Na ؉ channel complex, is required for the initiation and propagation of the cardiac action potential. Mutations in Na v 1.5 cause cardiac arrhythmias and sudden death. The cardiac Na ؉ channel functions as a protein complex; however, its complete components remain to be fully elucidated. A yeast two-hybrid screen identified a new candidate Na v 1.5-interacting protein, ␣B-crystallin. GST pull-down, co-immunoprecipitation, and immunostaining analyses validated the interaction between Na v 1.5 and ␣B-crystallin. Whole-cell patch clamping showed that overexpression of ␣B-crystallin significantly increased peak sodium current (I Na ) density, and the underlying molecular mechanism is the increased cell surface expression level of Na v 1.5 via reduced internalization of cell surface Na v 1.5 and ubiquitination of Na v 1.5. Knock-out of ␣B-crystallin expression significantly decreased the cell surface expression level of Na v 1.5. Co-immunoprecipitation analysis showed that ␣B-crystallin interacted with Nedd4-2; however, a catalytically inactive Nedd4-2-C801S mutant impaired the interaction and abolished the up-regulation of I Na by ␣B-crystallin. Na v 1.5 mutation V1980A at the interaction site for Nedd4-2 eliminated the effect of ␣B-crystallin on reduction of Na v 1.5 ubiquitination and increases of I Na density. Two disease-causing mutations in ␣B-crystallin, R109H and R151X (nonsense mutation), eliminated the effect of ␣B-crystallin on I Na . This study identifies ␣B-crystallin as a new binding partner for Na v 1.5. ␣B-Crystallin interacts with Na v 1.5 and increases I Na by modulating the expression level and internalization of cell surface Na v 1.5 and ubiquitination of Na v 1.5, which requires the protein-protein interactions between ␣B-crystallin and Na v 1.5 and between ␣B-crystallin and functionally active Nedd4-2.Na v 1.5 is the pore-forming ␣ subunit of the major cardiac voltage-gated Na ϩ channel complex. It generates the sodium current (I Na ) 4 that plays an essential role in the initiation and propagation of the cardiac action potential (1-3). Mutations in the SCN5A gene (encoding Na v 1.5) cause several inherited arrhythmias, including atrial fibrillation, Brugada syndrome, long QT syndrome, progressive cardiac conduction defect disease, sick sinus syndrome, and dilated cardiomyopathy (4). Na v 1.5 exists in vivo in a multiprotein complex, which interacts with the actin cytoskeleton and the extracellular matrix to provide an important functional link between channel complexes, cardiac structure, and electrical functioning (5, 6). Several proteins have been reported to bind to Na v 1.5 (5-7). We have previously reported a small protein, MOG1, with a function in nucleocytoplasmic protein transport that interacts directly with Na v 1.5, promotes trafficking of Na v 1.5 to the cell surface, and increases peak I Na density (4, 6). Specifically, MOG1 facilitates export of Na v 1.5 from the endoplasmic reticulum as well as targeting of Na v 1.5...

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

αB-Crystallin Interacts with Nav1.5 and Regulates Ubiquitination and Internalization of Cell Surface Nav1.5

Huang

Journal of Biological Chemistry

Liu

et al. 2016

Self Cite

“…Growing evidence has documented the familial aggregation of AF and an enhanced susceptibility to AF in the close relatives of patients with AF, indicating that hereditary defects may play an important role in the pathogenesis of AF in a subset of patients (8)(9)(10)(11)(12)(13)(14). Genome-wide linkage analysis with polymorphic genetic markers mapped multiple susceptibility loci for AF on human chromosomes 10q22, 6q14-16, 11p15.5, 5p13, 10p11-q21 and 5p15, of which AF-causing mutations in 2 genes, KCNQ1 on chromosome 11p15.5 and NUP155 on chromosome 5p13, were identified and functionally characterized (15)(16)(17)(18)(19)(20)(21). Additionally, a genetic scan of candidate genes revealed a long list of AF associated genes, including KCNE2, KCNE3, KCNE5, KCNH2, KCNJ2, KCNA5, SCN5A, SCN1B, SCN2B, SCN3B, NPPA, GJA1 and GJA5 (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37).…”

Section: Introductionmentioning

confidence: 99%

A novel GATA5 loss-of-function mutation underlies lone atrial fibrillation

Huang

International Journal of Molecular Medicine

et al. 2012

Abstract. Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is associated with significantly increased morbidity and mortality. Cumulative evidence highlights the importance of genetic defects in the pathogenesis of AF. However, AF is of remarkable heterogeneity and the genetic determinants of AF in a vast majority of patients remain illusive. In this study, the coding exons and splice junctions of the GATA5 gene, which encodes a zinc-finger transcription factor essential for normal cardiogenesis, were sequenced in 118 unrelated patients with lone AF. The available relatives of the index patient carrying an identified mutation and 200 unrelated ethnically-matched healthy individuals used as controls were genotyped. The functional effect of the mutant GATA5 was characterized in contrast to its wild-type counterpart using a luciferase reporter assay system. As a result, a novel heterozygous GATA5 mutation, p.W200G, was identified in a family with AF inherited as an autosomal dominant trait. The mutation was absent in 200 control individuals and the altered amino acid was completely conserved evolutionarily across species. Functional analysis showed that the mutation of GATA5 was associated with a significantly decreased transcriptional activity. These findings provide novel insight into the molecular mechanism involved in AF, suggesting potential implications for the early prophylaxis and genespecific therapy of AF.

“…While the structural heart diseases or systemic disorders, such as coronary artery disease, rheumatic heart disease, cardiomyopathy, congenital heart defects, pericarditis, congestive heart failure, hypertension, hyperthyroidism, and electrolyte imbalance, predispose to AF (4), AF also occurs in individuals without any known risk factors and growing evidence points to a genetic basis for the pathogenesis of AF (5)(6)(7)(8)(9)(10)(11)(12)(13). Furthermore, several chromosomal loci linked to AF have been mapped and AF-related mutations in multiple genes, including the connexin40 encoding cardiac gap junction membrane channel protein ·5, have been identified (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). However, AF is a genetically heterogeneous disorder and the molecular basis of AF remains unknown in the majority of cases (27).…”

Section: Introductionmentioning

confidence: 99%

Connexin40 nonsense mutation in familial atrial fibrillation

Yang

Zhang²,

Wang³

et al. 2010

Int J Mol Med

Abstract. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia associated with substantial morbidity and mortality. Genetic variants play important roles in the pathogenesis of AF. However, AF is a genetically heterogeneous disorder, and the genetic determinants in most patients with AF remain to be identified. In this study, the entire coding region of the connexin40 gene, encoding the cardiac gap junction membrane channel protein ·5, was sequenced in 126 unrelated probands with familial AF. A novel heterozygous mutation, c.145C>T, in connexin40, was identified in a proband. The mutation was predicted to introduce a premature stop codon at amino acid position 49 (p.Q49X). This nonsense mutation was present in all the living relatives of the mutation carrier, co-segregating with AF in the family with a penetrance of 100%. However, it was absent in 200 ethnically matched unrelated control individuals. The findings suggest a pathogenic link between the compromised connexin40 function and familial AF, hence providing new insight into the molecular mechanisms involved in AF.