Desmoplakin and clinical manifestations of desmoplakin cardiomyopathy / 中华医学杂志(英文版)

Desmoplakin (DSP), encoded by the DSP gene, is the main desmosome component and is abundant in the myocardial tissue. There are three DSP isoforms that assume the role of supporting structural stability through intercellular adhesion. It has been found that DSP regulates the transcription of adipogenic and fibrogenic genes, and maintains appropriate electrical conductivity by regulating gap junctions and ion channels. DSP is essential for normal myocardial development and the maintenance of its structural functions. Studies have suggested that DSP gene mutations are associated with a variety of hereditary cardiomyopathy, such as arrhythmia cardiomyopathy, dilated cardiomyopathy (DCM), left ventricular noncompaction, and is also closely associated with the Carvajal syndrome, Naxos disease, and erythro-keratodermia-cardiomyopathy syndrome with skin and heart damage. The structure and function of DSP, as well as the clinical manifestations of DSP-related cardiomyopathy were reviewed in this article.

Desmoplakin expression silencing affects cardiac voltage-gated sodium channel Nav1.5 in HL-1 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the association of desmoplakin with the distribution and function of Nav1.5 by RNA silencing technology in HL-1 cells.</p><p><b>METHODS</b>HL-1 cells with desmoplakin expression suppression by RNA silencing were examined for desmoplakin and Nav1.5 protein expressions by Western blotting, and the distribution and co-location of desmoplakin and Nav1.5 protein were detected by immunofluorescence staining. Patch-clamp recording was applied to analyze the changes in whole-cell sodium current after desmoplakin silencing.</p><p><b>RESULTS</b>Compared with the untreated group and negative control group, the cells with desmoplakin silencing showed obviously reduced expressions of desmoplakin and Nav1.5 proteins. Co-localization of desmoplakin and Nav1.5 was detected at cell-cell contact in untreated and control conditions, and desmoplakin expression silencing induced a drastic redistribution of Nav1.5 with decreased peak current density (156.3∓6.2 vs 41.8∓3.1, n=6, P<0.05), a shift in voltage dependence of steady-state inactivation (-42 mV vs -61 mV, n=5, P<0.05), and prolonged time of recovery from inactivation.</p><p><b>CONCLUSION</b>Desmoplakin silencing caused redistribution of Nav1.5 protein and also changes in its electrophysiological properties in HL-1 cells.</p>

Autoantibodies Against Desmoplakin I and II in Patients with Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis / 대한피부과학회지

BACKGOUND: It has been suggested that humoral immune mechanisms might play a role in the pathogenesis of a subset of patients with Stevens-Johnson syndrome (SJS). Circulating antibodies (Abs) against desmoplakin I and II (dp I/II) were detected in a subset of patients with SJS, which could impair the function of desmosome-keratinfilament complexes resulting in suprabasal acantholysis as a humoral autoimmune phenomenon. OBJECTIVE: The purpose of this study was to detect the presence of circulating autoantibodies against dp I/II in the sera of patients with toxic epidermal necrolysis (TEN), as well as SJS. METHOD: In this study, the sera of ten patients with TEN and SJS were investigated. Immunoblot analyses of extracts of EDTA-separated normal human epidermis were performed. We also performed an indirect immunofluorescence (IIF) test using normal human skin, mouse tongue, esophagus, and rat bladder. In addition, we performed direct IF studies using three perilesional tissues obtained from one patient of SJS and two patients of TEN. RESULTS: By immunoblotting using human epidermal extract, 215-kD and 250-kD proteins were detected in the sera of six out of ten patients with TEN and SJS. IIF using normal human foreskin demonstrated dense IgG deposits in the intercellular spaces and cytoplasmic membrane of epidermal cells in all sera of patients with SJS and TEN. In the direct IF test, IgG and IgA deposits appeared in an intercellular staining of epidermis of perilesional skin from two out of three patients with TEN and SJS. CONCLUSION: These findings suggest that circulating Abs against dp I/II and constitutive desmosomal plaque proteins might play a role in the pathogenesis of SJS and TEN.

Formation of Intercellular Junction between Cardiomyocyte and H9c2 Cell Line in Co-Culture / 체질인류학회지

Recently, new treatments for human heart disease such as ischemia, infarction, cardiomyopathy, coronary heart disease have been developed. transplantation various kinds of cells from skeletal muscle, endothelium, mesenchyme, hemopoietic tissue to injured area after infarction were challenged. It's so called 'Cell Transplantation'. This therapeutic strategy already adopted and got a good result in clinical trial. But several limitations are still remained, including ethics, donor cell numbers, side effects, therapeutic efficiency. In this research, we investigated the formation of intercellular junction and synchronous contraction between cardiomyocyte and H9c2 cell line in co-culture to establish experimental model in vitro for cell transplantation. For this purpose, two kinds of cells, primary cultured cardiomyocyte and H9c2 (cardiomyoblast cell line) were used. Cultured cardiomyocytes had repetitive contraction-relaxation pattern along longitudinal axis both in single and coculture. But their contractions were slower, less regular, less strong in co-culture than in cardiomyocyte culture only. H9c2 cells did not contracted actively themselves, but moved toward cardiomyocyte passively coincided with contraction. In contact region between two kinds of cells, there was no signal after immunocytochemical staining labeled with connexin43 (gap junction), desmoplakin (desmosome), N-cadherin (adherent junction) even though they had membrane contact. Moreover, F-actin and striation were less developed. These results suggested that co-culture system interfere with remodelling of contractile apparatus, intercellular junction formation as well as contraction-relaxation. Furthermore cardiomyocyte could not induce H9c2 cells differentiation into cardiomyocyte. Therefore, much more research would be essential for clinical application of cell transplantation and this study would be the basic source for further study of new therapy of myocardial disease and building up in vitro model.

Endodermal sinus tumor: immunophenotypic expression of a carcinoma

A series of five endodermal sinus tumors was studied for their cytoskeletal and other phenotypic markers. They included 2 ovarian, 2 testicular, and 1 inguinal tumors. The cytoskeletal expression was also studied by gel electrophoresis and immunoblotting. Every tumor was diffusely and strongly immunostained for cytokeratin. By SDS-PAGE and immunoblotting, cytokeratins 8 & 18 were detected. Vimentin was focally coexpressed in 4 cases. The stroma was diffusely immunostained for vimentin. None of them expressed desmin, neurofilament, or glial filament protein. Desmoplakin was expressed only in one ovarian tumor. Alpha-fetoprotein and S-100 protein were also diffusely positive among the neoplastic cells; intracytoplasmic globules were especially strongly immunostained. These findings suggest that endodermal sinus tumors represent a group of pure malignant epithelial neoplasms, and may be regarded as primitive carcinomas.

The Effects of Calcium and Retinoic Acid on Epidermal Desmosomes / 대한피부과학회지

BACKGROUND: Desmosomes are adhesive intercellular junctions that form an important component of the junction complexes of epithelial cells. They provide intercellular links between the intermediate filament cytoskeletons of adjacent cells and are thus involved in maintaining the structural integrity of tissues. OBJECTIVE: Calcium and retinoids are major regulators of epidermal differentiation and their role on keratin proteins are well known. However, their effects on desmosome moleucles are unknown. To address this question we initiated a study of the effects of these epidermal differentiation regulators on desmosomal components, i.e., desmoplakin, desmoglein, and pemphigus antigens. METHODS: We used monoclonal antibodies against desmoplakin(DP) and desmoglein(DG), and sera from patients with pemphigus vulgaris(PV), pemphigus foliaceus(PF) and paraneoplastic pemphigus (PNP) to study the effects of calcium and retinoic acids, which are major regulators of epidermal differentation, on desmosomal protein formation in human cultured deratinocytes. We performed immunofluorescence, immunoblotting and immunoprecipitation study using human keratinocytes cultured in high calcium media with or without retinoic acid and in low calcium media with or without retinoic acid. RESULTS: 1. In low calcium (0.15mM) media, PV antigen and DG were produced in a small amount and it appeared that these desmosomal proteins were located in cytosol. Whereas in high calcium (1.8mM) media, production of these desmosomal proteins was increased not they were assembled at the desmosomal structures located in cell-cell contact margins. 2. PF antigen, which was identical to the DG, were not produced or expressed in cultured keratinocytes even when cultured in high calcium media. 3. PNP antigen and DP were produced in cultured keratinocytes grown in both high low calcium media but their production was increased in high calcium media and only in high calcium media they were assembled at the desmosomal structures. 4. Retinoic acids induced loosening of cell-cell contacts of cultured keratinocytes and decreased the production of desmosomal proteins. CONCLUSION: Our results suggests calcium is a major regulator of the production and assembly of desmosomal proteins including pemphigus antigens, but PF sera and monoclonal antibodies against DG show different antigen binding characteristics. It appears that retinoic acids inhibit production of desmosomal proteins.