Desmoglein 2 and desmocollin 2 depletions promote malignancy through distinct mechanisms in triple-negative and luminal breast cancer.

BACKGROUND: Aberrant expressions of desmoglein 2 (Dsg2) and desmocollin 2(Dsc2), the two most widely distributed desmosomal cadherins, have been found to play various roles in cancer in a context-dependent manner. Their specific roles on breast cancer (BC) and the potential mechanisms remain unclear. METHODS: The expressions of Dsg2 and Dsc2 in human BC tissues and cell lines were assessed by using bioinformatics analysis, immunohistochemistry and western blotting assays. Wound-healing and Transwell assays were performed to evaluate the cells' migration and invasion abilities. Plate colony-forming and MTT assays were used to examine the cells' capacity of proliferation. Mechanically, Dsg2 and Dsc2 knockdown-induced malignant behaviors were elucidated using western blotting assay as well as three inhibitors including MK2206 for AKT, PD98059 for ERK, and XAV-939 for ß-catenin. RESULTS: We found reduced expressions of Dsg2 and Dsc2 in human BC tissues and cell lines compared to normal counterparts. Furthermore, shRNA-mediated downregulation of Dsg2 and Dsc2 could significantly enhance cell proliferation, migration and invasion in triple-negative MDA-MB-231 and luminal MCF-7 BC cells. Mechanistically, EGFR activity was decreased but downstream AKT and ERK pathways were both activated maybe through other activated protein tyrosine kinases in shDsg2 and shDsc2 MDA-MB-231 cells since protein tyrosine kinases are key drivers of triple-negative BC survival. Additionally, AKT inhibitor treatment displayed much stronger capacity to abolish shDsg2 and shDsc2 induced progression compared to ERK inhibition, which was due to feedback activation of AKT pathway induced by ERK inhibition. In contrast, all of EGFR, AKT and ERK activities were attenuated, whereas ß-catenin was accumulated in shDsg2 and shDsc2 MCF-7 cells. These results indicate that EGFR-targeted therapy is not a good choice for BC patients with low Dsg2 or Dsc2 expression. Comparatively, AKT inhibitors may be more helpful to triple-negative BC patients with low Dsg2 or Dsc2 expression, while therapies targeting ß-catenin can be considered for luminal BC patients with low Dsg2 or Dsc2 expression. CONCLUSION: Our finding demonstrate that single knockdown of Dsg2 or Dsc2 could promote proliferation, motility and invasion in triple-negative MDA-MB-231 and luminal MCF-7 cells. Nevertheless, the underlying mechanisms were cellular context-specific and distinct.

Desmocollin-2 inhibits cell proliferation and promotes apoptosis in hepatocellular carcinoma via the ERK/c-MYC signaling pathway.

Hepatocellular carcinoma (HCC) is one of the most common cancers around the world with a poor prognosis. The main reason for poor prognosis is early stage HCC is inconspicuous so it is difficult to detect and effective treatment strategies are lacking for advanced HCC. In this context, novel molecular targets are urgently needed for the diagnosis and therapy of HCC. In this study, we investigated the expression level, biological function, and relative mechanism of Desmocollin-2(DSC2) in HCC. DSC2 expression levels were decreased significantly in HCC cell lines SMMC-7721(7721), Huh7, HCC-LM3(LM3), and MHCC-97H(97H), especially in LM3 cells, compared with human liver cell line L02(L02). DSC2 overexpression in LM3 cells could inhibit the proliferation (in vitro and in vivo), colony formation, migration, and invasion abilities of HCC cells, and promote cell apoptosis, while DSC2 inhibition in 7721 cells performed the opposite effect. Consistent with these results, regulating DSC2 expression in 7721 and LM3 cells could affect the expression levels of apoptosis-related proteins (Bax, Bcl-2, c-Caspase-3, Caspase-3, Caspase-8, and Survivin) and cell cycle-related proteins (Cyclin D1, Cyclin B1, CDK1, and CDK2). Furthermore, DSC2 expression was significantly negatively correlated with the levels of p-ERK and c-MYC in both LM3 and 7721 cell lines. These findings confirmed that DSC2 overexpression could inhibit the proliferation, migration, and invasion abilities while promoting apoptosis of HCC cells via the ERK/c-MYC signaling pathway. In a conclusion, DSC2 was a tumor suppressor with low expression in liver cancer.

Premature Termination Codon in 5' Region of Desmoplakin and Plakoglobin Genes May Escape Nonsense-Mediated Decay through the Reinitiation of Translation.

Arrhythmogenic cardiomyopathy is a heritable heart disease associated with desmosomal mutations, especially premature termination codon (PTC) variants. It is known that PTC triggers the nonsense-mediated decay (NMD) mechanism. It is also accepted that PTC in the last exon escapes NMD; however, the mechanisms involving NMD escaping in 5'-PTC, such as reinitiation of translation, are less known. The main objective of the present study is to evaluate the likelihood that desmosomal genes carrying 5'-PTC will trigger reinitiation. HL1 cell lines were edited by CRISPR/Cas9 to generate isogenic clones carrying 5'-PTC for each of the five desmosomal genes. The genomic context of the ATG in-frame in the 5' region of desmosomal genes was evaluated by in silico predictions. The expression levels of the edited genes were assessed by Western blot and real-time PCR. Our results indicate that the 5'-PTC in PKP2, DSG2 and DSC2 acts as a null allele with no expression, whereas in the DSP and JUP gene, N-truncated protein is expressed. In concordance with this, the genomic context of the 5'-region of DSP and JUP presents an ATG in-frame with an optimal context for the reinitiation of translation. Thus, 5'-PTC triggers NMD in the PKP2, DSG2* and DSC2 genes, whereas it may escape NMD through the reinitiation of the translation in DSP and JUP genes, with no major effects on ACM-related gene expression.

Uniting biobank resources reveals novel genetic pathways modulating susceptibility for atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a common chronic inflammatory skin disease with high heritability. Previous genome-wide association studies have identified several loci predisposing to AD. These findings explain approximately 30% of the variance in AD susceptibility, suggesting that further work is required to fully understand the genetic underpinnings. OBJECTIVE: We sought to gain additional understanding of the genetic contribution to AD risk by using biobank resources. METHODS: We completed a genome-wide meta-analysis of AD in 796,661 individuals (Ncases = 22,474) from the FinnGen study, the Estonian Biobank, and the UK Biobank. We further performed downstream in silico analyses to characterize the risk variants at the novel loci. RESULTS: We report 30 loci associating with AD (P < 5 × 10-8), 5 of which are novel. In 2 of the novel loci, we identified missense mutations with deleterious predictions in desmocollin 1 and serpin family B member 7, genes encoding proteins crucial to epidermal strength and integrity. CONCLUSIONS: These findings elucidate novel genetic pathways involved in AD pathophysiology. The likely involvement of desmocollin 1 and serpin family B member 7 in AD pathogenesis may offer opportunities for the development of novel treatment strategies for AD in the future.

Overlap phenotypes of the left ventricular noncompaction and hypertrophic cardiomyopathy with complex arrhythmias and heart failure induced by the novel truncated DSC2 mutation.

BACKGROUND: The left ventricular noncompaction cardiomyopathy (LVNC) is a rare subtype of cardiomyopathy associated with a high risk of heart failure (HF), thromboembolism, arrhythmia, and sudden cardiac death. METHODS: The proband with overlap phenotypes of LVNC and hypertrophic cardiomyopathy (HCM) complicates atrial fibrillation (AF), ventricular tachycardia (VT), and HF due to the diffuse myocardial lesion, which were diagnosed by electrocardiogram, echocardiogram and cardiac magnetic resonance imaging. Peripheral blood was collected from the proband and his relatives. DNA was extracted from the peripheral blood of proband for high-throughput target capture sequencing. The Sanger sequence verified the variants. The protein was extracted from the skin of the proband and healthy volunteer. The expression difference of desmocollin2 was detected by Western blot. RESULTS: The novel heterozygous truncated mutation (p.K47Rfs*2) of the DSC2 gene encoding an important component of desmosomes was detected by targeted capture sequencing. The western blots showed that the expressing level of functional desmocollin2 protein (~ 94kd) was lower in the proband than that in the healthy volunteer, indicating that DSC2 p.K47Rfs*2 obviously reduced the functional desmocollin2 protein expression in the proband. CONCLUSION: The heterozygous DSC2 p.K47Rfs*2 remarkably and abnormally reduced the functional desmocollin2 expression, which may potentially induce the overlap phenotypes of LVNC and HCM, complicating AF, VT, and HF.

Clinical Findings and Diagnostic Yield of Arrhythmogenic Cardiomyopathy Through Genomic Screening of Pathogenic or Likely Pathogenic Desmosome Gene Variants.

BACKGROUND: Genomic screening holds great promise for presymptomatic identification of hidden disease, and prevention of dramatic events, including sudden cardiac death associated with arrhythmogenic cardiomyopathy (ACM). Herein, we present findings from clinical follow-up of carriers of ACM-associated pathogenic/likely pathogenic desmosome variants ascertained through genomic screening. METHODS: Of 64 548 eligible participants in Geisinger MyCode Genomic Screening and Counseling program (2015-present), 92 individuals (0.14%) identified with pathogenic/likely pathogenic desmosome variants by clinical laboratory testing were referred for evaluation. We reviewed preresult medical history, patient-reported family history, and diagnostic testing results to assess both arrhythmogenic right ventricular cardiomyopathy and left-dominant ACM. RESULTS: One carrier had a prior diagnosis of dilated cardiomyopathy with arrhythmia; no other related diagnoses or diagnostic family history criteria were reported. Fifty-nine carriers (64%) had diagnostic testing in follow-up. Excluding the variant, 21/59 carriers satisfied at least one arrhythmogenic right ventricular cardiomyopathy task force criterion, 11 (52%) of whom harbored DSP variants, but only 5 exhibited multiple criteria. Six (10%) carriers demonstrated evidence of left-dominant ACM, including high rates of atypical late gadolinium enhancement by magnetic resonance imaging and nonsustained ventricular tachycardia. Two individuals received new cardiomyopathy diagnoses and received defibrillators for primary prevention. CONCLUSIONS: Genomic screening for pathogenic/likely pathogenic variants in desmosome genes can uncover both left- and right-dominant ACM. Findings of overt cardiomyopathy were limited but were most common in DSP-variant carriers and notably absent in PKP2-variant carriers. Consideration of the pathogenic/likely pathogenic variant as a major criterion for diagnosis is inappropriate in the setting of genomic screening.

Autoantibodies to DSC3 in Pemphigus Exclusively Recognize Calcium-Dependent Epitope in Extracellular Domain 2.

Pemphigus is a group of autoimmune bullous diseases characterized by the presence of autoantibodies against adhesion molecules, desmogleins, and desmocollins (DSCs). The pathogenicity of anti-DSC3 antibodies in pemphigus has been demonstrated; however, its characteristics have not yet been elucidated. We aimed to analyze the characteristics of anti-DSC3 antibodies using DSC3 domain‒swapped desmoglein 2 molecules in which the prosequence and five extracellular (EC) domains of desmoglein 2 were replaced with the corresponding domains of human DSC3. Using these proteins, we established an ELISA and analyzed sera from 56 patients with pemphigus. In 34 pemphigus sera positive for DSC3 full-EC domains, 15 sera (44.1%) were positive for EC2 domain, whereas other domains were rarely positive. We assessed the reactivity to a calcium-dependent epitope in DSC3 by ELISA with EDTA. The reactivity with the EC2 domain was mostly compromised in the presence of EDTA. In the in vitro assay, IgG from patients with paraneoplastic pemphigus preadsorbed with EC2 prevented both reduction of DSC3 and keratinocyte dissociation as compared with that with EDTA-treated EC2. This study revealed a predominant recognition of calcium-dependent epitopes in EC2 domain by anti-DSC3 antibodies and its pathogenicity on keratinocyte adhesion through DSC3 depletion.

Deciphering DSC2 arrhythmogenic cardiomyopathy electrical instability: From ion channels to ECG and tailored drug therapy.

BACKGROUND: Severe ventricular rhythm disturbances are the hallmark of arrhythmogenic cardiomyopathy (ACM), and are often explained by structural conduction abnormalities. However, comprehensive investigations of ACM cell electrical instability are lacking. This study aimed to elucidate early electrical myogenic signature of ACM. METHODS: We investigated a 41-year-old ACM patient with a missense mutation (c.394C>T) in the DSC2 gene, which encodes desmocollin 2. Pathogenicity of this variant was confirmed using a zebrafish DSC2 model system. Control and DSC2 patient-derived pluripotent stem cells were reprogrammed and differentiated into cardiomyocytes (hiPSC-CM) to examine the specific electromechanical phenotype and its modulation by antiarrhythmic drugs (AADs). Samples of the patient's heart and hiPSC-CM were examined to identify molecular and cellular alterations. RESULTS: A shortened action potential duration was associated with reduced Ca2+ current density and increased K+ current density. This finding led to the elucidation of previously unknown abnormal repolarization dynamics in ACM patients. Moreover, the Ca2+ mobilised during transients was decreased, and the Ca2+ sparks frequency was increased. AAD testing revealed the following: (1) flecainide normalised Ca2+ transients and significantly decreased Ca2+ spark occurrence and (2) sotalol significantly lengthened the action potential and normalised the cells' contractile properties. CONCLUSIONS: Thorough analysis of hiPSC-CM derived from the DSC2 patient revealed abnormal repolarization dynamics, prompting the discovery of a short QT interval in some ACM patients. Overall, these results confirm a myogenic origin of ACM electrical instability and provide a rationale for prescribing class 1 and 3 AADs in ACM patients with increased ventricular repolarization reserve.

CircRAB11FIP1 promoted autophagy flux of ovarian cancer through DSC1 and miR-129.

At present, no systematic and in-depth study is available on the function and potential mechanisms of circular RNA in autophagy. This study aimed to screen the expression profiles of circRNA, miRNA, and mRNA of ovarian cancer cells induced by Torin 1 (10 µM). The expression profiles of circRNA, miRNA, and mRNA were analyzed with next-generation sequencing technology. CircRAB11FIP1 expression was elevated in epithelial ovarian cancer (EOC) tissues than in normal ovarian tissues. Silencing circRAB11FIP1 inhibited the autophagic flux of ovarian cancer SKOV3 cells. However, circRAB11FIP1 overexpression activated the autophagic flux of ovarian cancer A2780 cells. CircRAB11FIP1-induced autophagy accelerated EOC proliferation and invasion. Also, circRAB11FIP1 directly bound to miR-129 and regulated its targets ATG7 and ATG14. CircRAB11FIP1 bound to desmocollin 1to facilitate its interaction with ATG101. Also, circRAB11FIP1 directly bound to the mRNA of fat mass and obesity-associated protein and promoted its expression. Then, circRAB11FIP1 mediated mRNA expression levels of ATG5 and ATG7 depending on m6A. In general, this study demonstrated that circRAB11FIP1 regulated ATG7 and ATG14 by sponging miR-129. The data suggested that circRAB11FIP1 might serve as a candidate biomarker for EOC diagnosis and treatment.

Regulation of intestinal epithelial intercellular adhesion and barrier function by desmosomal cadherin desmocollin-2.

The role of desmosomal cadherin desmocollin-2 (Dsc2) in regulating barrier function in intestinal epithelial cells (IECs) is not well understood. Here, we report the consequences of silencing Dsc2 on IEC barrier function in vivo using mice with inducible intestinal-epithelial-specific Dsc2 knockdown (KD) (Dsc2ERΔIEC). While the small intestinal gross architecture was maintained, loss of epithelial Dsc2 influenced desmosomal plaque structure, which was smaller in size and had increased intermembrane space between adjacent epithelial cells. Functional analysis revealed that loss of Dsc2 increased intestinal permeability in vivo, supporting a role for Dsc2 in the regulation of intestinal epithelial barrier function. These results were corroborated in model human IECs in which Dsc2 KD resulted in decreased cell-cell adhesion and impaired barrier function. It is noteworthy that Dsc2 KD cells exhibited delayed recruitment of desmoglein-2 (Dsg2) to the plasma membrane after calcium switch-induced intercellular junction reassembly, while E-cadherin accumulation was unaffected. Mechanistically, loss of Dsc2 increased desmoplakin (DP I/II) protein expression and promoted intermediate filament interaction with DP I/II and was associated with enhanced tension on desmosomes as measured by a Dsg2-tension sensor. In conclusion, we provide new insights on Dsc2 regulation of mechanical tension, adhesion, and barrier function in IECs.

Androgen downregulates desmocollin-2 in association with induction of mesenchymal transition of breast MDA-MB-453 cancer cells.

Desmosomes are cellular structures that are critical in cell-cell adhesion and in maintaining tissue architecture. Changes in the expression of desmocollin-2 (DSC2) have been noted during tumor progression into an invasive phenotype and as cells undergo epithelial-mesenchymal transition. We have previously reported that breast MDA-MB-453 cancer cells, a luminal androgen receptor (AR) model of triple-negative breast cancer, acquire mesenchymal features when treated with the AR agonist, dihydrotestosterone (DHT). We have therefore investigated androgen regulation of the expression and cellular localization of DSC2 in MDA-MB-453 cells. Treatment of the cells with DHT resulted in a dose-dependent reduction in DSC2 protein levels and dispersion of its membrane localization concomitant with AR- and ß-catenin-mediated mesenchymal transition of cells. A significant correlation was revealed between decreased expression of AR and increased expression of DSC2 in patient samples. In addition, whereas lower expression of AR was associated with a reduced overall and recurrence-free survival of breast cancer patients, higher expression of DSC2 was found in invasive breast tumors than in normal breast cells and was correlated with lower patient survival. Upon knocking down DSC2, the cells became elongated, mesenchymal-like, and slightly, but insignificantly, more migratory. The addition of DHT further stimulated cell elongation and migration. DSC2 siRNA-transfected cells reverted to a normal epithelial morphology upon inhibition of ß-catenin. These results highlight the role of DSC2 in maintaining the epithelial morphology of MDA-MB-453 cells and the negative regulation of the desmosomal protein by DHT during stimulation of the androgen-induced, ß-catenin-mediated mesenchymal transition of the cells.

The Transcription Factor p63 Is a Direct Effector of IL-4- and IL-13-Mediated Repression of Keratinocyte Differentiation.

Atopic Dermatitis is an inflammatory skin disease associated with broad defects in skin barrier function caused by increased levels of type-2 cytokines (IL-4 and IL-13) that repress keratinocyte (KC) differentiation. Although crucial in mediating allergic disease, the mechanisms for gene repression induced by type-2 cytokines remain unclear. In this study, we determined that gene repression requires the master regulator of the epidermal differentiation program, p63. We found that type-2 cytokine-mediated inhibition of the expression of genes involved in early KC differentiation, including keratin 1, keratin 10, and DSC-1, is reversed by p63 blockade. Type-2 cytokines, through p63, also regulate additional genes involved in KC differentiation, including CHAC-1, STC2, and CALML5. The regulation of the expression of these genes is ablated by p63 small interfering RNA as well. In addition, we found that IL-4 and IL-13 and Staphylococcus aureus lipoteichoic acid work in combination through p63 to further suppress the early KC differentiation program. Finally, we found that IL-4 and IL-13 also inhibit the activity of Notch, a transcription factor required to induce early KC differentiation. In conclusion, type-2 cytokine-mediated gene repression and blockade of KC differentiation are multifactorial, involving pathways that converge on transcription factors critical for epidermal development, p63 and Notch.

A homozygous DSC2 deletion associated with arrhythmogenic cardiomyopathy is caused by uniparental isodisomy.

AIMS: We aimed to unravel the genetic, molecular and cellular pathomechanisms of DSC2 truncation variants leading to arrhythmogenic cardiomyopathy (ACM). METHODS AND RESULTS: We report a homozygous 4-bp DSC2 deletion variant c.1913_1916delAGAA, p.Q638LfsX647hom causing a frameshift carried by an ACM patient. Whole exome sequencing and comparative genomic hybridization analysis support a loss of heterozygosity in a large segment of chromosome 18 indicating segmental interstitial uniparental isodisomy (UPD). Ultrastructural analysis of the explanted myocardium from a mutation carrier using transmission electron microscopy revealed a partially widening of the intercalated disc. Using qRT-PCR we demonstrated that DSC2 mRNA expression was substantially decreased in the explanted myocardial tissue of the homozygous carrier compared to controls. Western blot analysis revealed absence of both full-length desmocollin-2 isoforms. Only a weak expression of the truncated form of desmocollin-2 was detectable. Immunohistochemistry showed that the truncated form of desmocollin-2 did not localize at the intercalated discs. In vitro, transfection experiments using induced pluripotent stem cell derived cardiomyocytes and HT-1080 cells demonstrated an obvious absence of the mutant truncated desmocollin-2 at the plasma membrane. Immunoprecipitation in combination with fluorescence measurements and Western blot analyses revealed an abnormal secretion of the truncated desmocollin-2. CONCLUSION: In summary, we unraveled segmental UPD as the likely genetic reason for a small homozygous DSC2 deletion. We conclude that a combination of nonsense mediated mRNA decay and extracellular secretion is involved in DSC2 related ACM.

Prevalence and Electronic Health Record-Based Phenotype of Loss-of-Function Genetic Variants in Arrhythmogenic Right Ventricular Cardiomyopathy-Associated Genes.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with variants in desmosome genes. Secondary findings of pathogenic/likely pathogenic variants, primarily loss-of-function (LOF) variants, are recommended for clinical reporting; however, their prevalence and associated phenotype in a general clinical population are not fully characterized. METHODS: From whole-exome sequencing of 61 019 individuals in the DiscovEHR cohort, we screened for putative loss-of-function variants in PKP2, DSC2, DSG2, and DSP. We evaluated measures from prior clinical ECG and echocardiograms, manually over-read to evaluate ARVC diagnostic criteria, and performed a PheWAS (phenome-wide association study). Finally, we estimated expected penetrance using Bayesian inference. RESULTS: One hundred forty individuals (0.23%; 59±18 years old at last encounter; 33% male) had an ARVC variant (G+). None had an existing diagnosis of ARVC in the electronic health record, nor significant differences in prior ECG or echocardiogram findings compared with matched controls without variants. Several G+ individuals satisfied major repolarization (n=4) and ventricular function (n=5) criteria, but this prevalence matched controls. PheWAS showed no significant associations of other heart disease diagnoses. Combining our best genetic and disease prevalence estimates yields an estimated penetrance of 6.0%. CONCLUSIONS: The prevalence of ARVC loss-of-function variants is ≈1:435 in a general clinical population of predominantly European descent, but with limited electronic health record-based evidence of phenotypic association in our population, consistent with a low penetrance estimate. Prospective deep phenotyping and longitudinal follow-up of a large sequenced cohort is needed to determine the true clinical relevance of an incidentally identified ARVC loss-of-function variant.

Proteomics Identification and Validation of Desmocollin-1 and Catechol-O-Methyltransferase as Proteins Associated with Breast Cancer Cell Migration and Metastasis.

Biological treatment of many cancers currently targets membrane bound receptors located on a cell surface. To identify novel membrane proteins associated with migration and metastasis of breast cancer cells, a more migrating subpopulation of MDA-MB-231 breast cancer cell line is selected and characterized. A high-resolution quantitative mass spectrometry with SILAC labeling is applied to analyze their surfaceome and it is compared with that of parental MDA-MB-231 cells. Among 824 identified proteins (FDR < 0.01), 128 differentially abundant cell surface proteins with at least one transmembrane domain are found. Of these, i) desmocollin-1 (DSC1) is validated as a protein connected with lymph node status of luminal A breast cancer, tumor grade, and Her-2 status by immunohistochemistry in the set of 96 primary breast tumors, and ii) catechol-O-methyltransferase is successfully verified as a protein associated with lymph node metastasis of triple negative breast cancer as well as with tumor grade by targeted data extraction from the SWATH-MS data of the same set of tissues. The findings indicate importance of both proteins for breast cancer development and metastasis and highlight the potential of biomarker validation strategy via targeted data extraction from SWATH-MS datasets.

Malignant Arrhythmia with Variants of Desmocollin-2 and Desmoplakin Genes.

Malignant arrhythmia is a fast cardiac arrhythmia that can lead to a hemodynamic abnormality within a short time, most of which is ventricular tachycardia or ventricular fibrillation (VF), which should be managed in time. Both organic and nonorganic cardiac diseases have the potential to cause malignant arrhythmia. We report a noteworthy case of malignant arrhythmia in a teenager during exercise. Transthoracic echocardiography, cardiac magnetic resonance (CMR), electrophysiological study, magnetic resonance imaging of the brain, electroencephalography, chest X-ray, and blood tests were all normal. Twelve-lead electrocardiography showed incomplete right bundle branch block (IRBBB). Two heterozygous missense variants of the desmocollin-2 gene (DSC2, c.G2446A/p.V816M) and desmoplakin gene (DSP, c.G3620A/p.R1207K) were detected in the peripheral blood of this teenager and his father by genetic testing, which encoded a desmosomal protein that was related to arrhythmogenic right ventricular cardiomyopathy (ARVC). In these two rare variants, DSC2 V816M has been reported but uncertain significance, whereas DSP R1207K is never reported. Therefore, the two site variants in DSC2 and DSP genes are likely to become a new research focus for diagnosis and treatment of ARVC in the future. Meanwhile, this report emphasizes that, in addition to a standard set of laboratory tests and examinations, genetic testing may be useful for analyzing the causes of malignant arrhythmia.

Clinical and genetic characteristics of nevus of Ota with choroidal melanoma in Chinese.

Purpose: The aim of the present study is to report the clinical and genetic characteristics of nevus of Ota with choroidal melanoma in Chinese patients. Patients and Methods: Patients with nevus of Ota with choroidal melanoma were identified by searching the computerized database and patient medical records of Beijing Shijitan Hospital and Shaanxi Yulin Tradition Chinese Medicine Hospital. The patients (2 men and 1 woman; mean age, 52 years; age range, 52­57 years) were all treated by enucleation or local endoresection, and choroidal melanoma was confirmed by pathologic examination. Results: The patients (2 men and 1 woman; mean age, 52 years; age range, 52­57 years) were all treated by enucleation or local endoresection, and choroidal melanoma was confirmed by pathologic examination. The study found that patients with nevus of Ota had higher risk for malignant melanoma. Furthermore, we found two suspicious gene mutations involving FAM111B and DSC2, that might contribute to the etiology of the disease. Conclusions: The results indicate that patients with nevus of Ota should undergo regular ophthalmological observation and be aware of the potential for malignancy.

Incorporation of desmocollin-2 into the plasma membrane requires N-glycosylation at multiple sites.

Desmocollin-2 (DSC2) is a desmosomal protein of the cadherin family. Desmosomes are multiprotein complexes, which are involved in cell adhesion of cardiomyocytes and of keratinocytes. The molecular structure of the complete extracellular domain (ECD) of DSC2 was recently described, revealing three disulfide bridges, four N-glycosylation sites, and four O-mannosylation sites. However, the functional relevance of these post-translational modifications for the protein trafficking of DSC2 to the plasma membrane is still unknown. Here, we generated a set of DSC2 mutants, in which we systematically exchanged all N-glycosylation sites, O-mannosylation sites, and disulfide bridges within the ECD and investigated the resulting subcellular localization by confocal laser scanning microscopy. Of note, all single and double N-glycosylation- deficient mutants were efficiently incorporated into the plasma membrane, indicating that the absence of these glycosylation sites has a minor effect on the protein trafficking of DSC2. However, the exchange of multiple N-glycosylation sites resulted in intracellular accumulation. Colocalization analysis using cell compartment trackers revealed that N-glycosylation- deficient DSC2 mutants were retained within the Golgi apparatus. In contrast, elimination of the four O-mannosylation sites or the disulfide bridges in the ECD has no obvious effect on the intracellular protein processing of DSC2. These experiments underscore the importance of N-glycosylation at multiple sites of DSC2 for efficient intracellular transport to the plasma membrane.