Missense mutations in desmocollin-2 N-terminus, associated with arrhythmogenic right ventricular cardiomyopathy, affect intracellular localization of desmocollin-2 in vitro.
BACKGROUND
Mutations in genes encoding desmosomal proteins have been reported to cause arrhythmogenic right ventricular cardiomyopathy (ARVC), an autosomal dominant disease characterised by progressive myocardial atrophy with fibro-fatty replacement. We screened 54 ARVC probands for mutations in desmocollin-2 (DSC2), the only desmocollin isoform expressed in cardiac tissue.


METHODS
Mutation screening was performed by denaturing high-performance liquid chromatography and direct sequencing. To evaluate the pathogenic potentials of the DSC2 mutations detected in patients affected with ARVC, full-length wild-type and mutated cDNAs were cloned in eukaryotic expression vectors to obtain a fusion protein with green fluorescence protein (GFP); constructs were transfected in neonatal rat cardiomyocytes and in HL-1 cells.


RESULTS
We identified two heterozygous mutations (c.304G>A (p.E102K) and c.1034T>C (p.I345T)) in two probands and in four family members. The two mutations p.E102K and p.I345T map to the N-terminal region, relevant to adhesive interactions. In vitro functional studies demonstrated that, unlike wild-type DSC2, the two N-terminal mutants are predominantly localised in the cytoplasm.


CONCLUSIONS
The two missense mutations in the N-terminal domain affect the normal localisation of DSC2, thus suggesting the potential pathogenic effect of the reported mutations. Identification of additional DSC2 mutations associated with ARVC may result in increased diagnostic accuracy with implications for genetic counseling.
Beffagna
Giorgia
G
Department of Biology, University of Padua, Padua, Italy. giorgia.beffagna@unipd.it
De Bortoli
Marzia
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Nava
Andrea
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Salamon
Michela
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Lorenzon
Alessandra
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Zaccolo
Manuela
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Mancuso
Luisa
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Sigalotti
Luca
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Bauce
Barbara
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Occhi
Gianluca
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Basso
Cristina
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Lanfranchi
Gerolamo
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Towbin
Jeffrey A
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Thiene
Gaetano
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Danieli
Gian Antonio
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Rampazzo
Alessandra
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D000293:Adolescent; D000328:Adult; D000818:Animals; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000235:genetics*; D002478:Cells, Cultured; D051187:Desmocollins / Q000235:genetics*; D005260:Female; D006580:Genetic Carrier Screening; D049452:Green Fluorescent Proteins; D006801:Humans; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D032383:Myocytes, Cardiac; D051381:Rats; D014162:Transfection
C081561:DSC2 protein, human; D051187:Desmocollins; D049452:Green Fluorescent Proteins