Document Detail


Abnormal connexin43 in arrhythmogenic right ventricular cardiomyopathy caused by plakophilin-2 mutations.
MedLine Citation:
PMID:  18662195     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disorder of cardiomyocyte intercalated disk proteins causing sudden death. Heterozygous mutations of the desmosomal protein plakophilin-2 (PKP-2) are the commonest genetic cause of ARVC. Abnormal gap junction connexin43 expression has been reported in autosomal dominant forms of ARVC (Naxos and Carvajal disease) caused by homozygous mutations of desmosomal plakoglobin and desmoplakin. In tissue culture, suppression of PKP-2 results in decreased expression of connexin43. We sought to characterize the expression and localization of connexin43 in patients with ARVC secondary to heterozygous PKP-2 mutations. Complete PKP-2 gene sequencing of 27 ARVC patients was utilized to identify mutant genotypes. Endomyocardial biopsies of identified carriers were then assessed by immunofluorescence to visualize intercalated disk proteins. N-cadherin was targeted to highlight intercalated disks, followed by counterstaining for PKP-2 or connexin43 using confocal double immunofluorescence microscopy. Immunofluorescence was quantified using an AdobeA Photoshop protocol, and colocalization coefficients were determined. PKP-2 siRNA experiments were performed in mouse cardiomyocyte (HL1) cell culture with Western blot analysis to assess connexin43 expression following PKP-2 suppression. Missense and frameshift mutations of the PKP-2 gene were found in four patients with biopsy material available for analysis. Immunofluorescent studies showed PKP-2 localization to the intercalated disk despite mutations, but associated with decreased connexin43 expression and abnormal colocalization. PKP-2 siRNA in HL1 culture confirmed decreased connexin43 expression. Reduced connexin43 expression and localization to the intercalated disk occurs in heterozygous human PKP-2 mutations, potentially explaining the delayed conduction and propensity to develop arrhythmias seen in this disease.
Authors:
Lee M Fidler; Gregory J Wilson; Fanfan Liu; Xuezhi Cui; Stephen W Scherer; Glenn P Taylor; Robert M Hamilton
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-07-26
Journal Detail:
Title:  Journal of cellular and molecular medicine     Volume:  13     ISSN:  1582-4934     ISO Abbreviation:  J. Cell. Mol. Med.     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2010-07-26     Completed Date:  2010-10-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101083777     Medline TA:  J Cell Mol Med     Country:  England    
Other Details:
Languages:  eng     Pagination:  4219-28     Citation Subset:  IM    
Affiliation:
Heart Centre-Cardiology Division, The Hospital for Sick Children, Toronto, ON, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Animals
Arrhythmogenic Right Ventricular Dysplasia / genetics*,  pathology*
Child, Preschool
Connexin 43 / metabolism*
Female
Fluorescent Antibody Technique
Heart Ventricles / metabolism,  pathology
Humans
Luminescent Measurements
Male
Mice
Microscopy, Confocal
Mutation / genetics*
Myocytes, Cardiac / metabolism,  pathology
Plakophilins / chemistry,  genetics*,  metabolism
Protein Transport
RNA, Small Interfering / metabolism
Chemical
Reg. No./Substance:
0/Connexin 43; 0/PKP2 protein, human; 0/Plakophilins; 0/RNA, Small Interfering

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