Serine/threonine-protein kinase D2-mediated phosphorylation of DSG2 threonine 730 promotes esophageal squamous cell carcinoma progression.

Desmoglein-2 (DSG2) is a transmembrane glycoprotein belonging to the desmosomal cadherin family, which mediates cell-cell junctions; regulates cell proliferation, migration, and invasion; and promotes tumor development and metastasis. We previously showed serum DSG2 to be a potential biomarker for the diagnosis of esophageal squamous cell carcinoma (ESCC), although the significance and underlying molecular mechanisms were not identified. Here, we found that DSG2 was increased in ESCC tissues compared with adjacent tissues. In addition, we demonstrated that DSG2 promoted ESCC cell migration and invasion. Furthermore, using interactome analysis, we identified serine/threonine-protein kinase D2 (PRKD2) as a novel DSG2 kinase that mediates the phosphorylation of DSG2 at threonine 730 (T730). Functionally, DSG2 promoted ESCC cell migration and invasion dependent on DSG2-T730 phosphorylation. Mechanistically, DSG2 T730 phosphorylation activated EGFR, Src, AKT, and ERK signaling pathways. In addition, DSG2 and PRKD2 were positively correlated with each other, and the overall survival time of ESCC patients with high DSG2 and PRKD2 was shorter than that of patients with low DSG2 and PRKD2 levels. In summary, PRKD2 is a novel DSG2 kinase, and PRKD2-mediated DSG2 T730 phosphorylation promotes ESCC progression. These findings may facilitate the development of future therapeutic agents that target DSG2 and DSG2 phosphorylation. © 2024 The Pathological Society of Great Britain and Ireland.

The role of desmoglein-2 in kidney disease.

Desmosomes are multi-protein cell-cell adhesion structures supporting cell stability and mechanical stress resilience of tissues, best described in skin and heart. The kidney is exposed to various mechanical stimuli and stress, yet little is known about kidney desmosomes. In healthy kidneys, we found desmosomal proteins located at the apical-junctional complex in tubular epithelial cells. In four different animal models and patient biopsies with various kidney diseases, desmosomal components were significantly upregulated and partly miss-localized outside of the apical-junctional complexes along the whole lateral tubular epithelial cell membrane. The most upregulated component was desmoglein-2 (Dsg2). Mice with constitutive tubular epithelial cell-specific deletion of Dsg2 developed normally, and other desmosomal components were not altered in these mice. When challenged with different types of tubular epithelial cell injury (unilateral ureteral obstruction, ischemia-reperfusion, and 2,8-dihydroxyadenine crystal nephropathy), we found increased tubular epithelial cell apoptosis, proliferation, tubular atrophy, and inflammation compared to wild-type mice in all models and time points. In vitro, silencing DSG2 via siRNA weakened cell-cell adhesion in HK-2 cells and increased cell death. Thus, our data show a prominent upregulation of desmosomal components in tubular cells across species and diseases and suggest a protective role of Dsg2 against various injurious stimuli.

Toward the understanding of DSG2 and CD46 interaction with HAdV-11 fiber, a super-complex analysis.

IMPORTANCE: The main limitation of oncolytic vectors is neutralization by blood components, which prevents intratumoral administration to patients. Enadenotucirev, a chimeric HAdV-11p/HAdV-3 adenovirus identified by bio-selection, is a low seroprevalence vector active against a broad range of human carcinoma cell lines. At this stage, there's still some uncertainty about tropism and primary receptor utilization by HAdV-11. However, this information is very important, as it has a direct influence on the effectiveness of HAdV-11-based vectors. The aim of this work is to determine which of the two receptors, DSG2 and CD46, is involved in the attachment of the virus to the host, and what role they play in the early stages of infection.

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.

Ser194Leu DSG2 mutation, associated with arrhythmogenic left ventricular cardiomyopathy and ventricular tachycardia.

INTRODUCTION: Arrhythmogenic cardiomyopathy (AC) is an inherited cardiomyopathy characterized by fibro-fatty replacement of cardiomyocytes, leading to life-threatening ventricular arrhythmia and heart failure. Pathogenic variants of desmoglein2 gene (DSG2) have been reported as genetic etiologies of AC. In contrast, many reported DSG2 variants are benign or variants of uncertain significance. Correct genetic variant classification is crucial for determining the best medical therapy for the patient and family members. METHODS: Pathogenicity of the DSG2 Ser194Leu variant that was identified by whole exome sequencing in a patient, who presented with ventricular tachycardia and was diagnosed with AC, was investigated by electron microscopy and immunohistochemical staining of endomyocardial biopsy sample. RESULTS: Electron microscopy demonstrated a widened gap in the adhering junction and a less well-organized intercalated disk region in the mutated cardiomyocytes compared to the control. Immunohistochemical staining in the proband diagnosed with AC showed reduced expression of desmoglein 2 and connexin 43 and intercalated disc distortion. Reduced expression of DSG2 and Connexin 43 were observed in cellular cytoplasm and gap junctions. Additionally, we detected perinuclear accumulation of DSG2 and Connexin 43 in the proband sample. CONCLUSION: Ser194Leu is a missense pathogenic mutation of DSG2 gene associated with arrhythmogenic left ventricular cardiomyopathy.

Up-regulation of Dsg2 confered stem cells with malignancy through wnt/ß-catenin signaling pathway.

In the previous study, we originally developed cancer stem cells (CSCs) models from mouse induced pluripotent stem cells (miPSCs) by culturing miPSCs in the conditioned medium of cancer cell lines, which mimiced as carcinoma microenvironment. However, the molecular mechanism of conversion in detail remains to be uncovered. Microarray analysis of the CSCs models in this study revealed Dsg2, one of the members of the desmosomal cadherin family, was up-regulated when compared with the original miPSCs. Moreover, the expression of key factors in Wnt/ß-catenin signaling pathway were also found up-regulated in one of the CSCs models, named miPS-LLCcm. An autocrine loop was implied between Dsg2 and Wnt/ß-catenin signaling pathway when miPSCs were treated with Wnt/ß-catenin signaling pathway activators, Wnt3a and CHIR99021, and when the CSCs model were treated with inhibitors, IWR-1 and IWP-2. Furthermore, the ability of proliferation and self-renewal in the CSCs model was markedly decreased in vitro and in vivo when Dsg2 gene was knocked down by shRNA. Our results showed that the Wnt/ß-catenin signaling pathway is activated by the up-regulation of Dsg2 expresssion during the conversion of miPSCs into CSCs implying a potential mechanism of the tranformation of stem cells into malignant phenotype.

Interplay between desmoglein2 and hypoxia controls metastasis in breast cancer.

Metastasis is the major cause of cancer death. An increased level of circulating tumor cells (CTCs), metastatic cancer cells that have intravasated into the circulatory system, is particularly associated with colonization of distant organs and poor prognosis. However, the key factors required for tumor cell dissemination and colonization remain elusive. We found that high expression of desmoglein2 (DSG2), a component of desmosome-mediated intercellular adhesion complexes, promoted tumor growth, increased the prevalence of CTC clusters, and facilitated distant organ colonization. The dynamic regulation of DSG2 by hypoxia was key to this process, as down-regulation of DSG2 in hypoxic regions of primary tumors led to elevated epithelial-mesenchymal transition (EMT) gene expression, allowing cells to detach from the primary tumor and undergo intravasation. Subsequent derepression of DSG2 after intravasation and release of hypoxic stress was associated with an increased ability to colonize distant organs. This dynamic regulation of DSG2 was mediated by Hypoxia-Induced Factor1α (HIF1α). In contrast to its more widely observed function to promote expression of hypoxia-inducible genes, HIF1α repressed DSG2 by recruitment of the polycomb repressive complex 2 components, EZH2 and SUZ12, to the DSG2 promoter in hypoxic cells. Consistent with our experimental data, DSG2 expression level correlated with poor prognosis and recurrence risk in breast cancer patients. Together, these results demonstrated the importance of DSG2 expression in metastasis and revealed a mechanism by which hypoxia drives metastasis.

Animal Models and Molecular Pathogenesis of Arrhythmogenic Cardiomyopathy Associated with Pathogenic Variants in Intercalated Disc Genes.

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/ß-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.

Phenotypic recapitulation and correction of desmoglein-2-deficient cardiomyopathy using human-induced pluripotent stem cell-derived cardiomyocytes.

Desmoglein-2, encoded by DSG2, is one of the desmosome proteins that maintain the structural integrity of tissues, including heart. Genetic mutations in DSG2 cause arrhythmogenic cardiomyopathy, mainly in an autosomal dominant manner. Here, we identified a homozygous stop-gain mutations in DSG2 (c.C355T, p.R119X) that led to complete desmoglein-2 deficiency in a patient with severe biventricular heart failure. Histological analysis revealed abnormal deposition of desmosome proteins, disrupted intercalated disk structures in the myocardium. Induced pluripotent stem cells (iPSCs) were generated from the patient (R119X-iPSC), and the mutated DSG2 gene locus was heterozygously corrected to a normal allele via homology-directed repair (HDR-iPSC). Both isogenic iPSCs were differentiated into cardiomyocytes [induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs)]. Multielectrode array analysis detected abnormal excitation in R119X-iPSC-CMs but not in HDR-iPSC-CMs. Micro-force testing of three-dimensional self-organized tissue rings (SOTRs) revealed tissue fragility and a weak maximum force in SOTRs from R119X-iPSC-CMs. Notably, these phenotypes were significantly recovered in HDR-iPSC-CMs. Myocardial fiber structures in R119X-iPSC-CMs were severely aberrant, and electron microscopic analysis confirmed that desmosomes were disrupted in these cells. Unexpectedly, the absence of desmoglein-2 in R119X-iPSC-CMs led to decreased expression of desmocollin-2 but no other desmosome proteins. Adeno-associated virus-mediated replacement of DSG2 significantly recovered the contraction force in SOTRs generated from R119X-iPSC-CMs. Our findings confirm the presence of a desmoglein-2-deficient cardiomyopathy among clinically diagnosed dilated cardiomyopathies. Recapitulation and correction of the disease phenotype using iPSC-CMs provide evidence to support the development of precision medicine and the proof of concept for gene replacement therapy for this cardiomyopathy.

Desmoglein-2 and COVID-19 complications: insights into its role as a biomarker, pathogenesis and clinical implications.

Desmoglein-2 (DSG2) has emerged as a potential biomarker for coronavirus disease 2019 (COVID-19) complications, particularly cardiac and cardiovascular involvement. The expression of DSG2 in lung tissues has been detected at elevated levels, and circulating DSG2 levels correlate with COVID-19 severity. DSG2 may contribute to myocardial injury, cardiac dysfunction and vascular endothelial dysfunction in COVID-19. Monitoring DSG2 levels could aid in risk stratification, early detection and prognostication of COVID-19 complications. However, further research is required to validate DSG2 as a biomarker. Such research will aim to elucidate its precise role in pathogenesis, establishing standardized assays for its measurement and possibly identifying therapeutic targets.

A host receptor enables type 1 pilus-mediated pathogenesis of Escherichia coli pyelonephritis.

Type 1 pili have long been considered the major virulence factor enabling colonization of the urinary bladder by uropathogenic Escherichia coli (UPEC). The molecular pathogenesis of pyelonephritis is less well characterized, due to previous limitations in preclinical modeling of kidney infection. Here, we demonstrate in a recently developed mouse model that beyond bladder infection, type 1 pili also are critical for establishment of ascending pyelonephritis. Bacterial mutants lacking the type 1 pilus adhesin (FimH) were unable to establish kidney infection in male C3H/HeN mice. We developed an in vitro model of FimH-dependent UPEC binding to renal collecting duct cells, and performed a CRISPR screen in these cells, identifying desmoglein-2 as a primary renal epithelial receptor for FimH. The mannosylated extracellular domain of human DSG2 bound directly to the lectin domain of FimH in vitro, and introduction of a mutation in the FimH mannose-binding pocket abolished binding to DSG2. In infected C3H/HeN mice, type 1-piliated UPEC and Dsg2 were co-localized within collecting ducts, and administration of mannoside FIM1033, a potent small-molecule inhibitor of FimH, significantly attenuated bacterial loads in pyelonephritis. Our results broaden the biological importance of FimH, specify the first renal FimH receptor, and indicate that FimH-targeted therapeutics will also have application in pyelonephritis.

Desmoglein 2 can undergo Ca2+-dependent interactions with both desmosomal and classical cadherins including E-cadherin and N-cadherin.

Desmoglein (Dsg) 2 is a ubiquitously expressed desmosomal cadherin. Particularly, it is present in all cell types forming desmosomes, including epithelial cells and cardiac myocytes and is upregulated in the autoimmune skin disease pemphigus. Thus, we here characterized the binding properties of Dsg2 in more detail using atomic force microscopy (AFM). Dsg2 exhibits homophilic interactions and also heterophilic interactions with the desmosomal cadherin desmocollin (Dsc) 2, and further with the classical cadherins E-cadherin (E-Cad) and N-cadherin (N-Cad), which may be relevant for cross talk between desmosomes and adherens junctions in epithelia and cardiac myocytes. We found that all homo- and heterophilic interactions were Ca2+-dependent. All binding forces observed are in the same force range, i.e., 30 to 40 pN, except for the Dsg2/E-Cad unbinding force, which with 45 pN is significantly higher. To further characterize the nature of the interactions, we used tryptophan, a critical amino acid required for trans-interaction, and a tandem peptide (TP) designed to cross-link Dsg isoforms. TP was sufficient to prevent the tryptophan-induced loss of Dsg2 interaction with the desmosomal cadherins Dsg2 and Dsc2; however, not with the classical cadherins E-Cad and N-Cad, indicating that the interaction modes of Dsg2 with desmosomal and classical cadherins differ. TP rescued the tryptophan-induced loss of Dsg2 binding on living enterocytes, suggesting that interaction with desmosomal cadherins may be more relevant. In summary, the data suggest that the ubiquitous desmosomal cadherin Dsg2 enables the cross talk with adherens junctions by interacting with multiple binding partners with implications for proper adhesive function in healthy and diseased states.

Desmoglein 2 mutation provokes skeletal muscle actin expression and accumulation at intercalated discs in murine hearts.

Arrhythmogenic cardiomyopathy (AC) is an incurable progressive disease that is linked to mutations in genes coding for components of desmosomal adhesions that are localized to the intercalated disc region, which electromechanically couples adjacent cardiomyocytes. To date, the underlying molecular dysfunctions are not well characterized. In two murine AC models, we find an upregulation of the skeletal muscle actin gene (Acta1), which is known to be a compensatory reaction to compromised heart function. Expression of this gene is elevated prior to visible morphological alterations and clinical symptoms, and persists throughout pathogenesis with an additional major rise during the chronic disease stage. We provide evidence that the increased Acta1 transcription is initiated through nuclear activation of the serum response transcription factor (SRF) by its transcriptional co-activator megakaryoblastic leukemia 1 protein (MKL1, also known as MRTFA). Our data further suggest that perturbed desmosomal adhesion causes Acta1 overexpression during the early stages of the disease, which is amplified by transforming growth factor ß (TGFß) release from fibrotic lesions and surrounding cardiomyocytes during later disease stages. These observations highlight a hitherto unknown molecular AC pathomechanism.

Human Desmoglein-2 and Human CD46 Mediate Human Adenovirus Type 55 Infection, but Human Desmoglein-2 Plays the Major Roles.

Human adenovirus type 55 (HAdV55) represents an emerging respiratory pathogen and causes severe pneumonia with high fatality in humans. The cellular receptors, which are essential for understanding the infection and pathogenesis of HAdV55, remain unclear. In this study, we found that HAdV55 binding and infection were sharply reduced by disrupting the interaction of viral fiber protein with human desmoglein-2 (hDSG2) but only slightly reduced by disrupting the interaction of viral fiber protein with human CD46 (hCD46). Loss-of-function studies using soluble receptors, blocking antibodies, RNA interference, and gene knockout demonstrated that hDSG2 predominantly mediated HAdV55 infection. Nonpermissive rodent cells became susceptible to HAdV55 infection when hDSG2 or hCD46 was expressed, but hDSG2 mediated more efficient HAd55 infection than hCD46. We generated two transgenic mouse lines that constitutively express either hDSG2 or hCD46. Although nontransgenic mice were resistant to HAdV55 infection, infection with HAdV55 was significantly increased in hDSG2+/+ mice but was much less increased in hCD46+/+ mice. Our findings demonstrate that both hDSG2 and hCD46 are able to mediate HAdV55 infection but hDSG2 plays the major roles. The hDSG2 transgenic mouse can be used as a rodent model for evaluation of HAdV55 vaccine and therapeutics.IMPORTANCE Human adenovirus type 55 (HAdV55) has recently emerged as a highly virulent respiratory pathogen and has been linked to severe and even fatal pneumonia in immunocompetent adults. However, the cellular receptors mediating the entry of HAdV55 into host cells remain unclear, which hinders the establishment of HAdV55-infected animal models and the development of antiviral approaches. In this study, we demonstrated that human desmoglein-2 (hDSG2) plays the major roles during HAdV55 infection. Human CD46 (hCD46) could also mediate the infection of HAdV55, but the efficiency was much lower than for hDSG2. We generated two transgenic mouse lines that express either hDSG2 or hCD46, both of which enabled HAd55 infection in otherwise nontransgenic mice. hDSG2 transgenic mice enabled more efficient HAdV55 infection than hCD46 transgenic mice. Our study adds to our understanding of HAdV55 infection and provides an animal model for evaluating HAdV55 vaccines and therapeutics.

Early inflammation precedes cardiac fibrosis and heart failure in desmoglein 2 murine model of arrhythmogenic cardiomyopathy.

The study of a desmoglein 2 murine model of arrhythmogenic cardiomyopathy revealed cardiac inflammation as a key early event leading to fibrosis. Arrhythmogenic cardiomyopathy (AC) is an inherited heart muscle disorder leading to ventricular arrhythmias and heart failure due to abnormalities in the cardiac desmosome. We examined how loss of desmoglein 2 (Dsg2) in the young murine heart leads to development of AC. Apoptosis was an early cellular phenotype, and RNA sequencing analysis revealed early activation of inflammatory-associated pathways in Dsg2-null (Dsg2-/-) hearts at postnatal day 14 (2 weeks) that were absent in the fibrotic heart of adult mice (10 weeks). This included upregulation of iRhom2/ADAM17 and its associated pro-inflammatory cytokines and receptors such as TNFα, IL6R and IL-6. Furthermore, genes linked to specific macrophage populations were also upregulated. This suggests cardiomyocyte stress triggers an early immune response to clear apoptotic cells allowing tissue remodelling later on in the fibrotic heart. Our analysis at the early disease stage suggests cardiac inflammation is an important response and may be one of the mechanisms responsible for AC disease progression.

S-acylated Golga7b stabilises DHHC5 at the plasma membrane to regulate cell adhesion.

S-acylation (palmitoylation) is the only fully reversible lipid modification of proteins; however, little is known about how protein S-acyltransferases (PATs) that mediate it are regulated. DHHC5 is a PAT that is mainly localised at the plasma membrane with roles in synaptic plasticity, massive endocytosis and cancer cell growth/invasion. Here, we demonstrate that DHHC5 binds to and palmitoylates a novel accessory protein Golga7b. Palmitoylation of Golga7b prevents clathrin-mediated endocytosis of DHHC5 and stabilises it at the plasma membrane. Proteomic analysis of the composition of DHHC5/Golga7b-associated protein complexes reveals a striking enrichment in adhesion proteins, particularly components of desmosomes. We show that desmoglein-2 and plakophilin-3 are substrates of DHHC5 and that DHHC5 and Golga7b are required for localisation of desmoglein-2 to the plasma membrane and for desmosomal patterning. Loss of DHHC5/Golga7b causes functional impairments in cell adhesion, suggesting these proteins have a wider role in cell adhesion beyond desmosome assembly. This work uncovers a novel mechanism of DHHC5 regulation by Golga7b and demonstrates a role for the DHHC5/Golga7b complex in the regulation of cell adhesion.

Chimeric oncolytic Ad5/3 virus replicates and lyses ovarian cancer cells through desmoglein-2 cell entry receptor.

Despite new therapies, the estimated 229 875 women living with ovarian cancer have a 5-year survival rate of 47.6%. This cavity-localized cancer lends itself to local administration of modalities, such as the oncolytic adenovirus (Ad) Ad5/3-D24-granulocyte-macrophage colony-stimulating factor virus (ONCOS-102). Its repeated administration to a patient with chemotherapy-refractory ovarian cancer induced CD8+ antitumor immune responses with the overall survival reaching 40 months. Here we probe the dominant receptor used by ONCOS-102 in four established epithelial ovarian cancer cell lines. Ad3 can use the desmoglein-2 (DSG2) and CD46 receptors on susceptible cells. DSG2 was nearly absent in A2780 cells but was expressed in more than 90% of OAW42, OVCAR3, and OV-90 cells. After 96 hours, ONCOS-102 treatment showed significant oncolytic activity (≧50%) in OAW42, OVCAR3, and OV-90 cells, but minimal activity in A2780 cells, suggesting DSG2 as the dominant receptor for ONCOS-102. Furthermore, retrospective analyses of phase I clinical trial of ONCOS-102 treatment of 12 patients with varied tumors indicated a correlation between viral genomes in blood and DSG2 RNA expression. These data support the role of DSG2 expression on cancer cells in virus infectivity and the continued development of ONCOS-102 for ovarian cancer treatment.

Adenovirus Receptor Expression in Cancer and Its Multifaceted Role in Oncolytic Adenovirus Therapy.

Oncolytic adenovirus therapy is believed to be a promising way to treat cancer patients. To be able to target tumor cells with an oncolytic adenovirus, expression of the adenovirus receptor on the tumor cell is essential. Different adenovirus types bind to different receptors on the cell, of which the expression can vary between tumor types. Pre-existing neutralizing immunity to human adenovirus species C type 5 (HAdV-C5) has hampered its therapeutic efficacy in clinical trials, hence several adenoviral vectors from different species are currently being developed as a means to evade pre-existing immunity. Therefore, knowledge on the expression of appropriate adenovirus receptors on tumor cells is important. This could aid in determining which tumor types would benefit most from treatment with a certain oncolytic adenovirus type. This review provides an overview of the known receptors for human adenoviruses and how their expression on tumor cells might be differentially regulated compared to healthy tissue, before and after standardized anticancer treatments. Mechanisms behind the up- or downregulation of adenovirus receptor expression are discussed, which could be used to find new targets for combination therapy to enhance the efficacy of oncolytic adenovirus therapy. Additionally, the utility of the adenovirus receptors in oncolytic virotherapy is examined, including their role in viral spread, which might even surpass their function as primary entry receptors. Finally, future directions are offered regarding the selection of adenovirus types to be used in oncolytic adenovirus therapy in the fight against cancer.

Rare non-coding Desmoglein-2 variant contributes to Arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) has been linked to variants in the coding sequence of desmosomal genes. The potential contribution of non-coding desmoglein-2 (DSG2) variants for development of ARVC is undescribed. We sequenced 1450 base pairs upstream of ATG in the DSG2 gene in 65 unrelated patients diagnosed with ARVC (10 borderline cases). Identified variants was evaluated by cosegregation and allele population frequency analysis, in silico tools, immunohistological investigations of myocardial biopsies, gene reporter assays, electrophoretic mobility shift assays (EMSA), and chromatin immunoprecipitation. The genetic analysis identified one novel, rare heterozygous DSG2 upstream variant (-317G > A) in a genetically unexplained ARVC patient. The variant segregated with signs of disease, was absent in publicly available databases, and affected a predicted binding site for activating protein-1 (AP-1). Immunohistochemical analysis of a myocardial biopsy from the -317G > A patient showed a marked reduction in DSG2 protein levels compared to healthy controls. Luciferase reporter gene assays showed promoter activity of the identified DSG2 upstream region and a general reduction in transcriptional activity in the presence of the minor DSG2_A allele (p < .01). Moreover, the DSG2_A allele reduced DSG2 activation by TGF-beta1 and a protein kinase C pathway activator (PMA; all p < .001 vs. DSG2_G). EMSAs showed altered transcription factor binding in presence of the DSG2_A allele. Chromatin immunoprecipitation assays in wild type epithelial cells identified AP-1 components c-FOS and c-JUN at the -317 locus. In conclusion, the non-coding DSG2 promoter variant -317G > A reduces DSG2 transcription in vitro and reduced myocardial DSG2 protein levels were observed in vivo. Our data support a contribution of non-coding DSG2 variants to the pathogenesis of ARVC.

In vitro analysis of arrhythmogenic cardiomyopathy associated desmoglein-2 (DSG2) mutations reveals diverse glycosylation patterns.

Arrhythmogenic right ventricular cardiomyopathy is a heritable cardiac disease causing severe ventricular arrhythmias, heart failure and sudden cardiac death. It is mainly caused by mutations in genes encoding several structural proteins of the cardiac desmosomes including the DSG2 gene encoding the desmosomal cadherin desmoglein-2. Although the molecular structure of the extracellular domain of desmoglein-2 is known, it remains an open question, how mutations in DSG2 contribute to the pathogenesis of arrhythmogenic right ventricular cardiomyopathy. In the present study, we analyzed the impact of different DSG2 mutations on the glycosylation pattern using de-glycosylation assays, lectin blot analysis and genetic inhibition studies. Remarkably, wildtype and mutant desmoglein-2 displayed different glycosylation patterns, although the investigated DSG2 mutations do not directly affect the consensus sequences of the N-glycosylation sites. Our study reveals complex molecular interactions between DSG2 mutations and N-glycosylations of desmoglein-2, which may contribute to the molecular understanding of the patho-mechanisms associated with arrhythmogenic right ventricular cardiomyopathy.