BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized with progressive cardiac fibrosis and heart failure. However, the exact mechanism driving the progression of cardiac fibrosis and heart failure in ACM remains elusive. This study aims to investigate the underlying mechanisms of progressive cardiac fibrosis in ACM caused by newly identified Desmoglein-2 (DSG2) variation.
METHODS: We identified homozygous DSG2F531C variant in a family with 8 ACM patients using whole-exome sequencing and generated Dsg2F536C knock-in mice. Neonatal and adult mouse ventricular myocytes isolated from Dsg2F536C knock-in mice were used. We performed functional, transcriptomic and mass spectrometry analyses to evaluate the mechanisms of ACM caused by DSG2F531C variant.
RESULTS: All eight patients with ACM were homozygous for DSG2F531C variant. Dsg2F536C/F536C mice displayed cardiac enlargement, dysfunction, and progressive cardiac fibrosis in both ventricles. Mechanistic investigations revealed that the variant DSG2-F536C protein underwent misfolding, leading to its recognition by BiP within the endoplasmic reticulum, which triggered endoplasmic reticulum stress, activated the PERK-ATF4 signaling pathway and increased ATF4 levels in cardiomyocytes. Increased ATF4 facilitated the expression of TGF-β1 in cardiomyocytes, thereby activating cardiac fibroblasts through paracrine signaling and ultimately promoting cardiac fibrosis in Dsg2F536C/F536C mice. Notably, inhibition of the PERK-ATF4 signaling attenuated progressive cardiac fibrosis and cardiac systolic dysfunction in Dsg2F536C/F536C mice.
CONCLUSIONS: Hyperactivation of the ATF4/TGF-β1 signaling in cardiomyocytes emerges as a novel mechanism underlying progressive cardiac fibrosis in ACM. Targeting the ATF4/TGF-β1 signaling may be a novel therapeutic target for managing ACM.

BACKGROUND: Desmoglein-2 (DSG2) has been reported to play pivotal roles in various diseases. However, its roles in cervical cancer (CC) remain insufficiently elucidated. Here, we aimed to comprehensively explore the functional mechanisms of DSG2 in CC using bioinformatics and experimental methods.
METHODS: Several online databases, including Gene Expression Profiling Interactive Analysis (GEPIA), ONCOMINE, LinkedOmics, MetaScape, Human protein atlas (HPA), OMICS and single-cell RNA sequencing (scRNA-seq) data were used to explore the expression, prognosis, gene mutations, and potential signaling pathway of DSG2 in CC. Quantitative real-time PCR (qRT-PCR) and western blotting were used to measure DSG2 expression in collected samples. Experimental assays were conducted to verify the effects of dysregulated DSG2 on cervical cell lines in vitro.
RESULTS: Bioinformatic analyses revealed that DSG2 was significantly up-regulated in CC compared to normal cervical tissues at both mRNA and protein levels. Elevated DSG2 levels were also associated with poor prognosis and clinical parameters (e.g., cancer stages, tumor grade, nodal metastasis status, etc.). DSG2 expression was predominantly observed in epithelial cells, increasing with disease progression on a single-cell resolution. Additionally, up-regulation of DSG2 significantly enhanced tumor purity by reducing the infiltration of immune cells (e.g., B cells, T cells, NK cells, etc.). Over-expression of DSG2 was further validated in collected CC samples at both mRNA and protein levels. Knockdown of DSG2 markedly reduced the proliferation and invasion of CC cell lines in vitro.
CONCLUSIONS: In summary, elevated levels of DSG2 were significantly associated with poor prognosis and diminished immune infiltration in CC. Thus, DSG2 may serve as a potential therapeutic and diagnostic biomarker for CC.

OBJECTIVE: Investigating the expression and prognostic significance of adenovirus receptors DSG-2, CXADR and CD46 in head and neck cancer.
METHODS: 104 patients with HNSCC (77 OPSCC, 27 LSCC) were retrospectively included in the study. Immunohistochemical staining was performed on all selected slides to detect the expression of DSG-2, CXADR, CD46 and the immunoreactive score (IRS) was determined from the number of positively stained tumor cells and their staining intensity. Furthermore, the respective HPV status was determined by immunohistochemical staining against p16 and HPV-PCR.
RESULTS: 81.7 % of the tumors showed DSG-2, 34.6 % of the tumors showed CXADR and 57.7 % of the tumors showed CD46 expression. A high DSG-2 IRS correlated significantly with an advanced tumor size (p= 0.003), increased grading (p=0.012) and positive HPV status (p=0.024) in OPSCC. A high CXADR IRS was significantly associated with a positive lymph node status (p= 0.041) in LSCC and an advanced AJCC stage (p= 0.012) and a positive HPV status (p= 0.009) in OPSCC. No significant correlation could be shown regarding CD46 expression and clinical tumor data. There was no effect of DSG-2, CXADR, and CD46 expression on 5-year overall and on 5-year disease-free survival.
CONCLUSIONS: No prognostic significance of the expression of DSG-2, CXADR or CD46 in HNSCC was seen. DSG-2, CXADR and CD46 are expressed in HNSCC, so that optimization of oncotherapy with adenoviral vectors appears promising. Due to the significantly increased expression of DSG-2 and CXADR in advanced OPSCC tumors, there is potential for optimizing oncotherapy here in particular.

Precancerous cervical lesions are metaplastic alterations of epithelial cells of the cervix, eventually developing into cervical cancer. Despite primary and secondary prevention, the burden of cervical cancer remains high globally. Protein arginine methyltransferases (PRMT) represent post-translational modifications that interact with multiple signalling pathways, playing a role in epithelial-mesenchymal transition. In complex with desmoglein-2 (DSG2), a cell adhesion protein, both participate in the progression of dysplastic changes with potential malignant development. The presented study was performed on archival paraffin-embedded blocks from adult women. The studied samples were categorised into low-grade and high-grade intraepithelial lesions. Immunohistochemical analysis was used to observe subcellular localisation, immunoreaction intensity, and percentage of PRMT5- and DSG2-expressing cells, followed by statistical analysis. Preliminary results identified statistically significant differences between the expression and subcellular localisation of proteins in question in low-grade and high-grade squamous intraepithelial lesions. The primary goal of the presented study is to perceive the involvement of PRMT5 and DSG2 in the initiation and progression of cervical lesions. Our observations indicate the potential of the assessed proteins as prognostic markers. However, further studies of PRMT5 and DSG2 are required to provide greater insight into cervical carcinogenesis.

Acquired resistance to endocrine treatments remains a major clinical challenge. In this study, we found that desmoglein-2 (DSG2) plays a major role in acquired endocrine resistance and cellular plasticity in ER+ breast cancer (BC). By analysing the well-established fulvestrant-resistant ER+ BC model using single-cell RNA-seq, we revealed that ER inhibition leads to a specific increase in DSG2 in cancer cell populations, which in turn enhances desmosome formation in vitro and in vivo and cell phenotypic plasticity that promotes resistance to treatment. DSG2 depletion reduced tumorigenesis and metastasis in fulvestrant-resistant xenograft models and promoted fulvestrant efficiency. Mechanistically, DSG2 forms a desmosome complex with JUP and Vimentin and triggers Wnt/PCP signalling. We showed that elevated DSG2 levels, along with reduced ER levels and an activated Wnt/PCP pathway, predicted poor survival, suggesting that a DSG2high signature could be exploited for therapeutic interventions. Our analysis highlighted the critical role of DSG2-mediated desmosomal junctions following antiestrogen treatment.

Desmosomes are intercellular adhesion complexes providing mechanical coupling and tissue integrity. Previously, a correlation of desmosomal molecule expression with invasion and metastasis formation in several tumor entities was described together with a relevance for circulating tumor cell cluster formation. Here, we investigated the contribution of the desmosomal core adhesion molecule desmoglein-2 (DSG2) to the initial steps of liver metastasis formation by pancreatic cancer cells using a novel ex vivo liver perfusion mouse model. We applied the pancreatic ductal adenocarcinoma cell line AsPC-1 with and without a knockout (KO) of DSG2 and generated mouse lines with a hepatocyte-specific KO of the known interacting partners of DSG2 (DSG2 and desmocollin-2). Liver perfusion with DSG2 KO AsPC-1 cells led to smaller circulating cell clusters and a reduced number of cells adhering to murine livers compared to control cells. While this was independent of the expression levels of desmosomal adhesion molecules in hepatocytes, we show that increased cluster size of cancer cells, which correlates with stronger cell-cell adhesion and expression of desmosomal molecules, is a major factor contributing to the early phase of metastatic spreading. In conclusion, impaired desmosomal adhesion results in reduced circulating cell cluster size, which is relevant for seeding and attachment of metastatic cells to the liver.

Arrhythmogenic cardiomyopathy (ACM) is a familial heart disease characterized by cardiac dysfunction, arrhythmias, and myocardial inflammation. Exercise and stress can influence the disease\'s progression. Thus, an investigation of whether a high-fat diet (HFD) contributes to ACM pathogenesis is warranted. In a robust ACM mouse model, 8-week-old Desmoglein-2 mutant (Dsg2mut/mut) mice were fed either an HFD or rodent chow for 8 weeks. Chow-fed wildtype (WT) mice served as controls. Echo- and electrocardiography images pre- and post-dietary intervention were obtained, and the lipid burden, inflammatory markers, and myocardial fibrosis were assessed at the study endpoint. HFD-fed Dsg2mut/mut mice showed numerous P-wave perturbations, reduced R-amplitude, left ventricle (LV) remodeling, and reduced ejection fraction (%LVEF). Notable elevations in plasma high-density lipoprotein (HDL) were observed, which correlated with the %LVEF. The myocardial inflammatory adipokines, adiponectin (AdipoQ) and fibroblast growth factor-1, were substantially elevated in HFD-fed Dsg2mut/mut mice, albeit no compounding effect was observed in cardiac fibrosis. The HFD not only potentiated cardiac dysfunction but additionally promoted adverse cardiac remodeling. Further investigation is warranted, particularly given elevated AdipoQ levels and the positive correlation of HDL with the %LVEF, which may suggest a protective effect. Altogether, the HFD worsened some, but not all, disease phenotypes in Dsg2mut/mut mice. Notwithstanding, diet may be a modifiable environmental factor in ACM disease progression.

Arrhythmogenic cardiomyopathy (ACM) is a rare genetic cardiac disease characterized by the progressive substitution of myocardium with fibro-fatty tissue. Clinically, ACM shows wide variability among patients; symptoms can include syncope and ventricular tachycardia but also sudden death, with the latter often being its sole manifestation. Approximately half of ACM patients have been found with variations in one or more genes encoding cardiac intercalated discs proteins; the most involved genes are plakophilin 2 (PKP2), desmoglein 2 (DSG2), and desmoplakin (DSP). Cardiac intercalated discs provide mechanical and electro-metabolic coupling among cardiomyocytes. Mechanical communication is guaranteed by the interaction of proteins of desmosomes and adheren junctions in the so-called area composita, whereas electro-metabolic coupling between adjacent cardiac cells depends on gap junctions. Although ACM has been first described almost thirty years ago, the pathogenic mechanism(s) leading to its development are still only partially known. Several studies with different animal models point to the involvement of the Wnt/β-catenin signaling in combination with the Hippo pathway. Here, we present an overview about the existing murine models of ACM harboring variants in intercalated disc components with a particular focus on the underlying pathogenic mechanisms. Prospectively, mechanistic insights into the disease pathogenesis will lead to the development of effective targeted therapies for ACM.

BACKGROUND: Anti-desmoglein (Dsg)1 is produced in pemphigus foliaceus (PF), affecting exclusively the skin. Pemphigus vulgaris (PV) shows the production of anti-Dsg3 in the mucosal form, and anti-Dsg1 and 3 in the mucocutaneous form. Anti-Dsg3 autoantibodies have been rarely reported in PF.
OBJECTIVE: To determine the factors associated with the production and pathogenicity of anti-Dsg3 in PF.
METHODS: Comparative analytical study of three patients groups: 16 PF-anti-Dsg3+, and 42 PF-anti-Dsg3(-) and 22 PV treatment-naïve cases. Serum was used in the anti-Dsg1 and 3 ELISA, and in immunoblotting (IB) with human epidermis extract. The expression of Dsg1 and 3 in paraffin sections was analyzed by immunohistochemistry (IHC). HLA-DRB1 alleles were compiled from a database.
RESULTS: In the PF-anti-Dsg3+ group: age range similar to that of the PV group (p > 0.9999); predominance of the generalized form of PF (p = 0.002); anti-Dsg3 titers lower than those of PV (p < 0.0001); IB confirmed Dsg3 identification in one (8.33%) of 12 patients; IHC showed exclusive cytoplasmic internalization of Dsg1; HLA-DRB1 alleles of susceptibility to PF, with the absence of alleles associated with PV, in the five typed patients.
CONCLUSIONS: Most of the patients in the PF-anti-Dsg3+ group were undergoing treatment.
CONCLUSIONS: The presence of anti-Dsg3 antibodies in PF was related to older age (comparable to that of PV) and the generalized form of PF. The non-pathogenicity of anti-Dsg3 antibodies in PF can be attributed to the low serum anti-Dsg3 titers, the lack of Dsg3 internalization as detected by IHC, and the absence of PV-associated HLA-DRB1 alleles.

Desmoglein-2 mutations are detected in 5-10% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Endurance training accelerates the development of the ARVC phenotype, leading to earlier arrhythmic events. Homozygous Dsg2 mutant mice develop a severe ARVC-like phenotype. The phenotype of heterozygous mutant (Dsg2mt/wt) or haploinsufficient (Dsg20/wt) mice is still not well understood. To assess the effects of age and endurance swim training, we studied cardiac morphology and function in sedentary one-year-old Dsg2mt/wt and Dsg20/wt mice and in young Dsg2mt/wt mice exposed to endurance swim training. Cardiac structure was only occasionally affected in aged Dsg20/wt and Dsg2mt/wt mice manifesting as small fibrotic foci and displacement of Connexin 43. Endurance swim training increased the right ventricular (RV) diameter and decreased RV function in Dsg2mt/wt mice but not in wild types. Dsg2mt/wt hearts showed increased ventricular activation times and pacing-induced ventricular arrhythmia without obvious fibrosis or inflammation. Preload-reducing therapy during training prevented RV enlargement and alleviated the electrophysiological phenotype. Taken together, endurance swim training induced features of ARVC in young adult Dsg2mt/wt mice. Prolonged ventricular activation times in the hearts of trained Dsg2mt/wt mice are therefore a potential mechanism for increased arrhythmia risk. Preload-reducing therapy prevented training-induced ARVC phenotype pointing to beneficial treatment options in human patients.