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AIMS: Recent immunohistochemical studies observed the loss of plakoglobin (PG) from the intercalated disc (ID) as a hallmark of arrhythmogenic right ventricular cardiomyopathy (ARVC), suggesting a final common pathway for this disease. However, the underlying molecular processes are poorly understood. METHODS AND RESULTS: We have identified novel mutations in the desmosomal cadherin desmocollin 2 (DSC2 R203C, L229X, T275M, and G371fsX378). The two missense mutations (DSC2 R203C and T275M) have been functionally characterized, together with a previously reported frameshift variant (DSC2 A897fsX900), to examine their pathogenic potential towards PG's functions at the ID. The three mutant proteins were transiently expressed in various cellular systems and assayed for expression, processing, localization, and binding to other desmosomal components in comparison to wild-type DSC2a protein. The two missense mutations showed defects in proteolytic cleavage, a process which is required for the functional activation of mature cadherins. In both cases, this is thought to cause a reduction of functional DSC2 at the desmosomes in cardiac cells. In contrast, the frameshift variant was incorporated into cardiac desmosomes; however, it showed reduced binding to PG. CONCLUSION: Despite different modes of action, for all three variants, the reduced ability to provide a ligand for PG at the desmosomes was observed. This is in agreement with the reduced intensity of PG at these structures observed in ARVC patients.

Original publication

DOI

10.1093/cvr/cvq353

Type

Journal article

Journal

Cardiovasc Res

Publication Date

01/04/2011

Volume

90

Pages

77 - 87

Keywords

Animals, Arrhythmogenic Right Ventricular Dysplasia, Base Sequence, COS Cells, Cercopithecus aethiops, DNA Mutational Analysis, Desmocollins, Desmosomes, Humans, Ligands, Molecular Sequence Data, Mutation, Missense, Myocytes, Cardiac, Protein Binding, Protein Processing, Post-Translational, Rats, Transfection, gamma Catenin