Characterizing the Molecular Pathology of Arrhythmogenic Cardiomyopathy in Patient Buccal Mucosa Cells

Abstract

Background Analysis of myocardium has revealed mechanistic insights into arrhythmogenic cardiomyopathy but cardiac samples are difficult to obtain from probands and especially from family members. To identify a potential surrogate tissue, we characterized buccal mucosa cells. Methods and Results Buccal cells from patients, mutation carriers and controls were immunostained and analyzed in a blinded fashion. In additional studies, buccal cells were grown in vitro and incubated with SB216763. Immunoreactive signals for the desmosomal protein plakoglobin and the major cardiac gap junction protein Cx43 were markedly diminished in buccal mucosa cells from arrhythmogenic cardiomyopathy patients with known desmosomal mutations when compared with controls. Plakoglobin and Cx43 signals were also reduced in most family members who carried disease alleles but showed no evidence of heart disease. Signal for the desmosomal protein plakophilin-1 was reduced in buccal mucosa cells in patients with PKP2 mutations but not in those with mutations in other desmosomal genes. Signal for the desmosomal protein desmoplakin was reduced in buccal mucosa cells from patients with mutations in DSP, DSG2 or DSC2 but not in PKP2 or JUP. Abnormal protein distributions were reversed in cultured cells incubated with SB216763, a small molecule that rescues the disease phenotype in cardiac myocytes. Conclusions Buccal mucosa cells from arrhythmogenic cardiomyopathy patients exhibit changes in the distribution of cell junction proteins similar to those seen in the heart. These cells may prove useful in future studies of disease mechanisms and drug screens for effective therapies in arrhythmogenic cardiomyopathy.

SORBS2is a susceptibility gene to arrhythmogenic right ventricular cardiomyopathy

“…Intriguingly, Sorbs2 deficiency is associated with dramatical downregulation of Cx43 expression in mouse. Given the fact that marked reduction of Cx43 have been found in many ARVC patients 28 42, 43 , it would be interesting to investigate the underlying mechanism its contribution to arrhythmic phenotypes in ARVC.…”

Molecular mechanisms in the pathogenesis of arrhythmogenic cardiomyopathy

“…In a search for an inexpensive and readily accessible surrogate to study ACM, we have turned to the buccal mucosa, which can be easily and safely obtained by rubbing the inside of the cheek with a swab and smearing the collected cells on slides for microscopic and molecular analysis. Using this approach, we have found that buccal mucosa cells from ACM patients exhibit changes in the distribution of cell junction proteins similar to those seen in the heart (Figure 7) [29]. Similar reductions occur in buccal mucosa cells of many family members who carry disease alleles but show no clinical evidence of heart disease (and in whom analysis of endomyocardial biopsies is not feasible) [29].…”

“…Using this approach, we have found that buccal mucosa cells from ACM patients exhibit changes in the distribution of cell junction proteins similar to those seen in the heart (Figure 7) [29]. Similar reductions occur in buccal mucosa cells of many family members who carry disease alleles but show no clinical evidence of heart disease (and in whom analysis of endomyocardial biopsies is not feasible) [29]. Analysis of buccal swabs may, therefore, be useful in future studies of disease mechanisms in probands, identification of disease modifiers in family members, and drug screens to identify new therapies in ACM.…”

“…The patient with the PKP2 mutation also shows reduced signal for plakophilin-1, and the patient with the DSP mutation shows reduced signal for desmoplakin. Reproduced from Asimaki et al [29]. …”

Dilated Cardiomyopathy

“…For the majority of genetic cardiomyopathies, genetic testing is favored over EMB. Of the genetic cardiomyopathies, ARVC may be evaluated by EMB, although more recent work suggests that alternative and more easily accessible cell types can be used to diagnose ARVC and avoid EMB 42, 43 .…”