Annexin II light chain regulates sensory neuron-specific sodium channel expression

Nature ◽  
2002 ◽  
Vol 417 (6889) ◽  
pp. 653-656 ◽  
Author(s):  
Kenji Okuse ◽  
Misbah Malik-Hall ◽  
Mark D. Baker ◽  
W-Y. Louisa Poon ◽  
Haeyoung Kong ◽  
...  
FEBS Letters ◽  
2004 ◽  
Vol 558 (1-3) ◽  
pp. 114-118 ◽  
Author(s):  
W.-Y.Louisa Poon ◽  
Misbah Malik-Hall ◽  
John N. Wood ◽  
Kenji Okuse

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Subat Turdi ◽  
Jeffrey A Towbin

Introduction: Arrhythmogenic cardiomyopathy (AC) is characterized by bi-ventricular dilation, fibro-fatty infiltration and life-threatening arrhythmias. Disruptions in cardiac voltage-gated sodium channel (Nav1.5) expression and function are known to cause arrhythmias. We have demonstrated that cardiac-specific overexpression of human mutant desmoplakin (DSP, Tg-R2834H) in mice leads to AC. However, whether mutant DSP expression in the heart affects the Nav1.5 distribution and function are unknown Hypothesis: Here, we tested whether Nav1.5 localization and expression are altered in the R2834H-Tg mouse hearts. Methods: Primary cardiomyocytes and frozen myocardial sections from non-transgenic (NTg), wild-type DSP (Tg-DSP) and Tg-R2834H mice were used for immunofluorescence studies to assess subcellular localization of DSP, desmin, Nav1.5, Cx43, plakoglobin and β-catenin. Western blot and qPCR were used for quantitative analysis. Results: Double staining of cardiomyocytes from NTg mice with DSP and Nav1.5 revealed that Nav1.5 was colocalized with DSP at the intercalated discs (IDs). In contrast, Tg-R2834H cardiomyocytes exhibited marked increase of mutant DSP expression at the IDs concomitant with a reduction in Nav1.5 immunoreactive signals. Tg-R2834H cardiomyocytes also revealed an aberration of DSP and desmin colocalizations at the IDs. There were not obvious differences in Cx43 expression between the genotypes, although the redistribution of Cx43 from the IDs to the sarcolemma was evident in Tg-R2834H cardiomyocytes. qPCR results correlated with reduced Nav1.5 mRNA expression in the Tg-R2834H mouse hearts. Conclusions: Defective DSP protein expression in the heart disrupts Nav1.5 localization and expression, implying an interaction between DSP and Nav1.5 to orchestrate normal mechanical and electrical coupling. Further electrophysiology studies to assess whole-cell Na + currents in these cardiomyocytes will provide insight into DSP and Nav1.5 interaction.


Nature ◽  
2007 ◽  
Vol 447 (7146) ◽  
pp. 856-859 ◽  
Author(s):  
Katharina Zimmermann ◽  
Andreas Leffler ◽  
Alexandru Babes ◽  
Cruz Miguel Cendan ◽  
Richard W. Carr ◽  
...  

Author(s):  
Mark D. McCauley ◽  
Liang Hong ◽  
Arvind Sridhar ◽  
Ambili Menon ◽  
Srikanth Perike ◽  
...  

Background: Epidemiological studies have established obesity as an independent risk factor for atrial fibrillation (AF), but the underlying pathophysiological mechanisms remain unclear. Reduced cardiac sodium channel expression is a known causal mechanism in AF. We hypothesized that obesity decreases Nav1.5 expression via enhanced oxidative stress, thus reducing I Na , and enhancing susceptibility to AF. Methods: To elucidate the underlying electrophysiological mechanisms a diet-induced obese mouse model was used. Weight, blood pressure, glucose, F 2 -isoprostanes, NOX2 (NADPH oxidase 2), and PKC (protein kinase C) were measured in obese mice and compared with lean controls. Invasive electrophysiological, immunohistochemistry, Western blotting, and patch clamping of membrane potentials was performed to evaluate the molecular and electrophysiological phenotype of atrial myocytes. Results: Pacing-induced AF in 100% of diet-induced obese mice versus 25% in controls ( P <0.01) with increased AF burden. Cardiac sodium channel expression, I Na and atrial action potential duration were reduced and potassium channel expression (Kv1.5) and current ( I Kur ) and F 2 -isoprostanes, NOX2, and PKC-α/δ expression and atrial fibrosis were significantly increased in diet-induced obese mice as compared with controls. A mitochondrial antioxidant reduced AF burden, restored I Na , I Ca,L , I Kur , action potential duration, and reversed atrial fibrosis in diet-induced obese mice as compared with controls. Conclusions: Inducible AF in obese mice is mediated, in part, by a combined effect of sodium, potassium, and calcium channel remodeling and atrial fibrosis. Mitochondrial antioxidant therapy abrogated the ion channel and structural remodeling and reversed the obesity-induced AF burden. Our findings have important implications for the management of obesity-mediated AF in patients. Graphic Abstract: A graphic abstract is available for this article.


2007 ◽  
Vol 52 (5) ◽  
pp. 494-502 ◽  
Author(s):  
E.V. Bird ◽  
P.P. Robinson ◽  
F.M. Boissonade

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