Coxsackievirus And Adenovirus Receptor Research Articles

Abstract 482: Advancing treatment for metastatic triple negative breast cancer: Liposomal oncolytic adenovirus as a novel neoadjuvant therapy

Abstract Introduction: Adenovirus type-5 (Ad) is considered a prominent viral vector in cancer therapy due to its modifiability for the selective lysis of cancer cells. However, challenges are posed in Ad delivery to cancers lacking coxsackievirus and adenovirus receptors (CARs). In response to this limitation, Ad-encapsulated DOTAP-folate liposomes were developed, which improved Ad delivery and heightened therapeutic efficacy through membrane fusion and folate receptor-mediated endocytosis. Methods: The 4T1 mammary carcinoma model, a CAR-negative triple-negative breast cancer (TNBC) cell line (ER-, PR-, HER2-), resistant to adenoviral infection, was utilized for studying the comparative in vitro transduction of green fluorescent protein (GFP)-expressing Ad (Ad-GFP). The study assessed Ad-GFP with and without DOTAP-folate liposomal encapsulation at a multiplicity of infection (MOI) of 50. Additionally, an oncolytic adenovirus, Ad-hTERT, with a human telomerase promoter, underwent liposomal encapsulation. CAR-negative 4T1 GFP-expressing cells and CAR-positive MDA-MB-231-GFP human breast adenocarcinoma TNBC cells were transduced in vitro at MOI 100 with Ad-hTERT, both with and without DOTAP-folate liposomal encapsulation. Results: CAR-negative 4T1 cells exhibited superior Ad-GFP transduction when encapsulated in DOTAP-folate liposomes, compared to the unencapsulated form (p < 0.001). For oncolytic adenovirus Ad-hTERT, encapsulation resulted in 100% cell lysis within 24 hours in 4T1-GFP cells, contrasting with 13% with unencapsulated Ad-hTERT (P < 0.0001). In CAR-positive MDA-MB-231-GFP TNBC cells, encapsulated Ad-hTERT showed enhanced efficacy, resulting in 100% cell lysis within 24 hours compared to 75% with unencapsulated Ad-hTERT (P < 0.001). Discussion: DOTAP-folate liposomal encapsulation enhances the efficacy of oncolytic Ad-hTERT in both CAR-negative and CAR-positive TNBC cells, establishing it as an optimal therapy for tumors with CAR heterogeneity. Ongoing in vivo studies with Balb/C immune-competent mice and the 4T1 tumor model will assess the effectiveness of encapsulation through intratumoral administration. This approach may extend the recurrence-free period post-surgical tumor removal. Citation Format: Jaimin R. Shah, Tao Dong, Abraham Phung, Sarah L. Blair, Omonigho Aisagbonhi, William C. Trogler, Andrew C. Kummel. Advancing treatment for metastatic triple negative breast cancer: Liposomal oncolytic adenovirus as a novel neoadjuvant therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 482.

CAR virus receptor mediates erythroid differentiation and migration and is downregulated in MDS.

Myelodysplastic syndromes (MDS) are myeloid neoplasms presenting with dysplasia in the bone marrow (BM) and peripheral cytopenia. In most patients anemia develops. We screened for genes that are expressed abnormally in erythroid progenitor cells (EP) and contribute to the pathogenesis of MDS. We found that the Coxsackie-Adenovirus receptor (CAR = CXADR) is markedly downregulated in CD45low/CD105+ EP in MDS patients compared to control EP. Correspondingly, the erythroblast cell lines HEL, K562, and KU812 stained negative for CAR. Lentiviral transduction of the full-length CXADR gene into these cells resulted in an increased expression of early erythroid antigens, including CD36, CD71, and glycophorin A. In addition, CXADR-transduction resulted in an increased migration against a serum protein gradient, whereas truncated CXADR variants did not induce expression of erythroid antigens or migration. Furthermore, conditional knock-out of Cxadr in C57BL/6 mice resulted in anemia and erythroid dysplasia. Finally, decreased CAR expression on EP was found to correlate with high-risk MDS and decreased survival. Together, CAR is a functionally relevant marker that is down-regulated on EP in MDS and is of prognostic significance. Decreased CAR expression may contribute to the maturation defect and altered migration of EP and thus their pathologic accumulation in the BM in MDS.

The junctional adhesion molecule-like protein (JAML) is important for the inflammatory response during contact hypersensitivity.

The junctional adhesion molecule-like protein (JAML) plays important roles in wound healing and activation of epidermal γδ T cells in mice. Whether JAML plays a role in contact hypersensitivity (CHS), the animal model of allergic contact dermatitis (ACD), is not known. To examine the role of JAML in CHS, we used various mouse models of CHS in JAML knockout (KO) and wild-type (WT) mice. Furthermore, the expression of the JAML ligand coxsackievirus and adenovirus receptor (CXADR) on keratinocytes was accessed in vitro and in vivo. JAML KO mice had a diminished inflammatory response during both the sensitization and elicitation phase of CHS and had reduced numbers of CD8+ and CD4+ T cells in the epidermis. Furthermore, interferon γ (IFNγ), interleukin 1β (IL-1β) and CXCL10 production were significantly reduced in JAML KO mice during the elicitation phase. We found that CD8+ T cells express JAML and that JAML is essential for rapid flare-up responses to contact allergens. Finally, we show that keratinocytes up-regulate the JAML ligand CXADR following exposure to contact allergens. Our study is the first to show a central role of JAML in CHS and reveals a potential new target for the treatment of ACD in humans.

Contributions of coxsackievirus adenovirus receptor to tumorigenesis.

Coxsackievirus and adenovirus receptor (CAR) is a transmembrane cell-cell adhesion receptor that forms homodimers across junctions and plays a key role in mediating epithelial barrier integrity. CAR can also heterodimerise with receptors on the surface of leukocytes and thus plays an additional role in mediating immune cell transmigration across epithelial tissues. Given the importance of both biological processes in cancer, CAR is emerging as a potential mediator of tumorigenesis as well as a target on cancer cells for viral therapy delivery. However, the emerging, often conflicting, evidence suggests that CAR function is tightly regulated and that contributions to disease progression are likely to be context specific. Here, we summarise reported roles for CAR in the context of cancer and draw on observations in other disease settings to offer a perspective on the potential relevance of this receptor as a therapeutic target for solid tumours.

Cigarette smoke extract impairs gingival epithelial barrier function

We previously showed that junctional adhesion molecule 1 (JAM1) and coxsackievirus and adenovirus receptor (CXADR), tight junction-associated proteins, have important roles to maintain epithelial barrier function in gingival tissues. Smoking is considered to be a significant risk factor for periodontal disease. The present study was conducted to examine the effects of cigarette smoke extract (CSE) on JAM1 and CXADR in human gingival epithelial cells. CSE was found to cause translocation of JAM1 from the cellular surface to EGFR-positive endosomes, whereas CXADR did not. Using a three-dimensional multilayered gingival epithelial tissue model, CSE administration was found to increase permeability to lipopolysaccharide and peptidoglycan, whereas overexpression of JAM1 in the tissue model prevented penetration by those substrates. Furthermore, vitamin C increased JAM1 expression, and inhibited penetration of LPS and PGN induced by CSE. These findings strongly suggest that CSE disrupts gingival barrier function via dislocation of JAM1, thus allowing bacterial virulence factors to penetrate into subepithelial tissues. Furthermore, they indicate that vitamin C increases JAM1 expression and prevents disruption of gingival barrier function by CSE.

Abstract LB267: Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma

Abstract Retinoblastoma is a cancer of the infant retina primarily driven by the loss of the Rb tumor suppressor gene, which is undruggable. Here, we identified an autocrine signaling, mediated by secreted frizzled-related protein 2 (SFRP2), which suppresses nitric oxide and enables retinoblastoma growth. SFRP2 silencing resulted in rapid production of nitric oxide, leading to p53-dependent growth arrest of retinoblastoma cells. We show that coxsackievirus and adenovirus receptor (CXADR) is the cell surface receptor for SFRP2 in retinoblastoma cells, that CXADR functions as a "dependence receptor," transmitting a growth inhibitory signal in the absence of SFRP2, and that the balance between SFRP2 and CXADR determines nitric oxide production. Accordingly, high SFRP2 RNA expression correlates with high-risk histopathologic features in retinoblastoma. Targeting SFRP2 signaling by SFRP2-binding peptides or by a pharmacological inhibitor rapidly induced nitric oxide and profoundly inhibited retinoblastoma growth in orthotopic xenograft models. These results reveal a cytokine signaling pathway that regulates nitric oxide production and retinoblastoma cell proliferation, and is amenable to therapeutic intervention. Citation Format: Panneerselvam Jayabal, Xiuye Ma, Kathryn M. Bondra, Yidong Chen, Peter J. Houghton, Yuzuru Shiio. Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB267.

Coxsackievirus and Adenovirus Receptor (CAR) Expression in Autopsy Tissues: Organ-Specific Patterns and Clinical Significance.

Coxsackievirus and adenovirus receptor (CAR) homologs have been identified in many species, and their proteins appeared to be highly conserved in evolution. While most of the human studies are about pathological conditions, the animal studies were more about the physiological and developmental functions of receptors. The expression of CAR is developmentally regulated, and its tissue localization is complex. Hence, we planned to study CAR expression in five different human organs at autopsy in different age groups. CAR expression was analyzed in the pituitary, heart, liver, pancreas, and kidney by immunohistochemistry, and CAR mRNA expression in the heart and pituitary by real-time PCR. In the current study, CAR expression was strong in cells of the anterior pituitary, hepatocytes, and bile ducts in the liver, acini, and pancreas and distal convoluted tubule/collecting duct in the kidney, with uniform expression in all age groups. We have noted high CAR expression in fetuses and infantile hearts, which get reduced drastically in adults due to its presumed developmental role in intrauterine life studied in animal models. In addition, the receptor was expressed in glomerular podocytes around the period of fetus viability (37 weeks) but not in early fetuses and adults. We have hypothesized that this intermittent expression could be responsible for the intercellular contact normally formed between the podocytes during the developmental phase. Pancreatic islets also showed increased expression after the emergence of the viability period but not in early fetuses and adults, which might be related to an increase in fetal insulin secretion at that particular age group.

Abstract 2743: Synergistic efficacy of telomerase-specific oncolytic adenoviral therapy and histone deacetylase inhibition in human hepatocellular carcinoma

Abstract Background: The telomerase-specific oncolytic adenovirus Telomelysin along with the histone deacetylase inhibitor AR42 have both demonstrated anticancer effects in preclinical models of human hepatocellular carcinoma (HCC). However, the clinical development of Telomelysin may be hindered by human antiviral immunity and tumor resistance. Combining oncolytic and epigenetic therapies has been reported to be a viable approach for treating various cancers. We investigated the potential synergism of Telomelysin and AR42 and the relevant underlying mechanisms. Method: HCC cell lines (PLC5 and Hep3B) were tested and median effect analysis was performed to estimate potential synergistic antiproliferative effects. Apoptosis was assessed by flow cytometry and Western blotting. The expression of coxsackievirus and adenovirus receptor (CAR) was measured through flow cytometry and immunofluorescence staining. Human telomerase reverse transcriptase (hTERT) mRNA expression was assessed by reverse transcription polymerase chain reaction. Western blotting was conducted to examine the activation of pivotal signaling pathways and the interferon (IFN) response. HCC cells constitutively overexpressing Akt were cloned for molecular mechanism verification. MK-2206 was used to inhibit the activation of Akt signaling. In vivo efficacy was determined through xenograft models of human HCC. Results: Telomelysin and AR42 exhibited synergistic antiproliferative effects in human HCC models in vitro and in vivo. Apoptosis induced by Telomelysin was significantly enhanced by AR42 in both PLC5 and Hep3B HCC cells. AR42 treatment unexpectedly attenuated the expression of the CAR and the mRNA levels of hTERT, which may be positively associated with the cytotoxicity of Telomelysin. Meanwhile, the cellular antiviral interferon response was not altered by AR42 treatment. Further, we found that Telomelysin enhanced Akt phosphorylation in HCC cells. AR42 reduced Telomelysin-induced phospho-Akt activation and enhanced Telomelysin-induced apoptosis. The correlation of Akt phosphorylation with drug-induced apoptosis was validated in HCC cells with upregulated or downregulated Akt signaling. Conclusions: Combination therapy with Telomelysin and AR42 demonstrates synergistic anti-HCC efficacy. Clinical trials investigating this new combination regimen are warranted. Keywords: Hepatocellular carcinoma, oncolytic adenovirus, Telomelysin, HDAC inhibitor, Akt Citation Format: Zhong-Zhe Lin, Mickey C-T. Hu, Chiun Hsu, Yao-Ming Wu, Yen-Shen Lu, Ja-An Annie Ho, Shiou-Hwei Yeh, Pei-Jer Chen, Ann-Lii Cheng. Synergistic efficacy of telomerase-specific oncolytic adenoviral therapy and histone deacetylase inhibition in human hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2743.

Macrophage-Specific Coxsackievirus and Adenovirus Receptor Deletion Enhances Macrophage M1 Polarity in CVB3-Induced Myocarditis

The coxsackievirus and adenovirus receptor (CAR) is very well known as an epithelial tight junction and cardiac intercalated disc protein; it mediates attachment and infection via the coxsackievirus B3 (CVB3) and type 5 adenovirus. Macrophages play important roles in early immunity during viral infections. However, the role of CAR in macrophages is not well studied in relation to CVB3 infection. In this study, the function of CAR was observed in the Raw264.7 mouse macrophage cell line. CAR expression was stimulated by treatment with lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α). In thioglycollate-induced peritonitis, the peritoneal macrophage was activated and CAR expression was increased. The macrophage-specific CAR conditional knockout mice (KO) were generated from lysozyme Cre mice. The expression of inflammatory cytokine (IL-1β and TNF-α) was attenuated in the KO mice's peritoneal macrophage after LPS treatment. In addition, the virus was not replicated in CAR-deleted macrophages. The organ virus replication was not significantly different in both wild-type (WT) and KO mice at days three and seven post-infection (p.i). However, the inflammatory M1 polarity genes (IL-1β, IL-6, TNF-α and MCP-1) were significantly increased, with increased rates of myocarditis in the heart of KO mice compared to those of WT mice. In contrast, type1 interferon (IFN-α and β) was significantly decreased in the heart of KO mice. Serum chemokine CXCL-11 was increased in the KO mice at day three p.i. compared to the WT mice. The attenuation of IFN-α and β in macrophage CAR deletion induced higher levels of CXCL-11 and more increased CD4 and CD8 T cells in KO mice hearts compared to those of WT mice at day seven p.i. These results demonstrate that macrophage-specific CAR deletion increased the macrophage M1 polarity and myocarditis in CVB3 infection. In addition, chemokine CXCL-11 expression was increased, and stimulated CD4 and CD8 T cell activity. Macrophage CAR may be important for the regulation of innate-immunity-induced local inflammation in CVB3 infection.

CAR links hypoxia signaling to improved survival after myocardial infarction

The coxsackievirus and adenovirus receptor (CAR) mediates homo- and heterotopic interactions between neighboring cardiomyocytes at the intercalated disc. CAR is upregulated in the hypoxic areas surrounding myocardial infarction (MI). To elucidate whether CAR contributes to hypoxia signaling and MI pathology, we used a gain- and loss-of-function approach in transfected HEK293 cells, H9c2 cardiomyocytes and CAR knockout mice. CAR overexpression increased RhoA activity, HIF-1α expression and cell death in response to chemical and physical hypoxia. In vivo, we subjected cardiomyocyte-specific CAR knockout (KO) and wild-type mice (WT) to coronary artery ligation. Survival was drastically improved in KO mice with largely preserved cardiac function as determined by echocardiography. Histological analysis revealed a less fibrotic, more compact lesion. Thirty days after MI, there was no compensatory hypertrophy or reduced cardiac output in hearts from CAR KO mice, in contrast to control mice with increased heart weight and reduced ejection fraction as signs of the underlying pathology. Based on these findings, we suggest CAR as a therapeutic target for the improved future treatment or prevention of myocardial infarction.

Human CXADR Gene – Coxsackie Virus Interaction Analysis to Identify Mutations and SNPs: An Exploratory In–Silico Approach

Coxsackie viruses belong to the enterovirus family which are usually isolated from the stomach and intestinal regions of the human body. The research we have undertook here is an exploration of the human CXADR gene using an in–silico approach to demonstrate the power and effectiveness of various online analytical tools. In this attempt to recognize the various mutations that occur in the CXADR gene, we have chosen 11 SNPs that have deleterious clinical significance. The junction expression profile reveals, the expression of CXADR gene in various tissues. In addition, gene expression profiles of various tissues have enabled us to predict the various diseases that might be caused due to the mutations with varying levels of confidence. The CXADR gene plays a very vital role in the interaction of the Coxsackie virus at the molecular level, as evidenced by their part played in causing a disease named Viral Myocarditis.

Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma.

Retinoblastoma is a cancer of the infant retina primarily driven by loss of the Rb tumor suppressor gene, which is undruggable. Here, we report an autocrine signaling, mediated by secreted frizzled-related protein 2 (SFRP2), which suppresses nitric oxide and enables retinoblastoma growth. We show that coxsackievirus and adenovirus receptor (CXADR) is the cell-surface receptor for SFRP2 in retinoblastoma cells; that CXADR functions as a "dependence receptor," transmitting a growth-inhibitory signal in the absence of SFRP2; and that the balance between SFRP2 and CXADR determines nitric oxide production. Accordingly, high SFRP2 RNA expression correlates with high-risk histopathologic features in retinoblastoma. Targeting SFRP2 signaling by SFRP2-binding peptides or by a pharmacological inhibitor rapidly induces nitric oxide and profoundly inhibits retinoblastoma growth in orthotopic xenograft models. These results reveal a cytokine signaling pathway that regulates nitric oxide production and retinoblastoma cell proliferation and is amenable to therapeutic intervention.

Relationship between villous atrophy and Wnt pathway gene expressions in pediatric celiac patients

Celiac disease is an autoimmune disease characterized by an abnormal immune response occurring in the small intestine linked to consumption of food containing gluten in individuals with a genetic predisposition. Dysregulation of Wnt signal transduction plays a role in the pathogenesis of many diseases including autoimmune diseases like celiac disease. In this study, the correlation of Wnt pathway gene expressions with each other and the correlation with clinical data were researched in pediatric celiac disease cases grouped according to the Marsh classification. Gene expression levels of FZD8, DVL2, LRP5, RHOA, CCND2, CXADR, and NFATC1, which are involved in the Wnt pathway, were determined using quantitative real-time polymerase chain reaction in 40 celiac disease and 30 healthy individuals. All cases with the short height symptom were observed to be in Marsh 3b\3c groups (p=0.03). The gene expressions of DVL2, CCND2, and NFATC1 were high in the Marsh 3b group, and these genes showed positive correlation with each other (p=0.002). LRP5 and CXADR gene expressions were lower in the Marsh 3b group compared to other Marsh groups, and these genes showed a positive correlation with each other (p=0.003). CCND2 gene expression was associated with Marsh 3b group, diarrhea, and vomiting symptoms. DVL2 gene expression was correlated with Marsh 2 group and constipation symptom (p<0.05). Wnt signaling in the early stages of the disease of Marsh 1-2 involves high expression of LRP5 and CXADR genes, while expression of these two genes reduces, and DVL2, CCND2, and NFATC1 gene expressions clearly increase with a transduction variation observed from Marsh 3a stage when villous atrophy begins to form. It appears that the Wnt pathway may contribute to disease progression through expression changes.

Full Remission of CAR-Deficient Tumors by DOTAP-Folate Liposome Encapsulation of Adenovirus.

Adenovirus (Ad)-based vectors have shown considerable promise for gene therapy. However, Ad requires the coxsackievirus and adenovirus receptor (CAR) to enter cells efficiently and low CAR expression is found in many human cancers, which hinder adenoviral gene therapies. Here, cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-folate liposomes (Df) encapsulating replication-deficient Ad were synthesized, which showed improved transfection efficiency in various CAR-deficient cell lines, including epithelial and hematopoietic cell types. When encapsulating replication-competent oncolytic Ad (TAV255) in DOTAP-folate liposome (TAV255-Df), the adenoviral structural protein, hexon, was readily produced in CAR-deficient cells, and the tumor cell killing ability was 5× higher than that of the non-encapsulated Ad. In CAR-deficient CT26 colon carcinoma murine models, replication-competent TAV255-Df treatment of subcutaneous tumors by intratumoral injection resulted in 67% full tumor remission, prolonged survival, and anti-cancer immunity when mice were rechallenged with cancer cells with no further treatment. The preclinical data shows that DOTAP-folate liposomes could significantly enhance the transfection efficiency of Ad in CAR-deficient cells and, therefore, could be a feasible strategy for applications in cancer treatment.

Development of Adenovirus Containing Liposomes Produced by Extrusion vs. Homogenization: A Comparison for Scale-Up Purposes.

Adenovirus (Ad) is a widely studied viral vector for cancer therapy as it can be engineered to cause selective lysis of cancer cells. However, Ad delivery is limited in treating cancers that do not have coxsackievirus and adenovirus receptors (CAR). To overcome this challenge, Ad-encapsulated liposomes were developed that enhance the delivery of Ads and increase therapeutic efficacy. Cationic empty liposomes were manufactured first, to which an anionic Ad were added, which resulted in encapsulated Ad liposomes through charge interaction. Optimization of the liposome formula was carried out with series of formulation variables experiments using an extrusion process, which is ideal for laboratory-scale small batches. Later, the optimized formulation was manufactured with a homogenization technique-A high shear rotor-stator blending, that is ideal for large-scale manufacturing and is in compliance with Good Manufacturing Practices (GMP). Comparative in vitro transduction, physicochemical characterization, long-term storage stability at different temperature conditions, and in vivo animal studies were performed. Ad encapsulated liposomes transduced CAR deficient cells 100-fold more efficiently than the unencapsulated Ad (p ≤ 0.0001) in vitro, and 4-fold higher in tumors injected in nude mice in vivo. Both extrusion and homogenization performed similarly-with equivalent in vitro and in vivo transduction efficiencies, physicochemical characterization, and long-term storage stability. Thus, two Ad encapsulated liposomes preparation methods used herein, i.e., extrusion vs. homogenization were equivalent in terms of enhanced Ad performance and long-term storage stability; this will, hopefully, facilitate translation to the clinic.

Surface pre-reacted glass-ionomer eluate protects gingival epithelium from penetration by lipopolysaccharides and peptidoglycans via transcription factor EB pathway.

Surface pre-reacted glass-ionomer (S-PRG) filler, produced by PRG technology for use with various dental materials, is bioactive and known to release ions from a glass-ionomer phase. We previously reported that coxsackievirus and adenovirus receptor (CXADR), a tight junction associated protein, was located in the epithelial barrier of gingival epithelium. In the present study, the tissue protective effects of an S-PRG eluate prepared with S-PRG filler were investigated using a three-dimensional human gingival epithelial tissue model. The results showed that the S-PRG eluate specifically induced CXADR expression at the transcriptional level of messenger RNA as well as the protein level, and also nuclear translocation of transcription factor EB (TFEB) in gingival epithelial cells. Furthermore, shigyakusan, a TFEB inhibitor, canceled induction of the CXADR protein by the S-PRG eluate. Additionally, gingival epithelial permeation by 40-kDa dextran, lipopolysaccharide, and peptidoglycan in the 3D-tissue models was prevented by the eluate, with those effects abrogated by knockdown of CXADR. These findings suggest that S-PRG eluate increases CXADR expression via the TFEB pathway, thus inhibiting penetration of bacterial virulence factors into subepithelial tissues.

The magic of MAGI-1: A scaffolding protein with multi signalosomes and functional plasticity.

MAGI-1 is a critical cellular scaffolding protein with over 110 different cellular and microbial protein interactors. Since the discovery of MAGI-1 in 1997, MAGI-1 has been implicated in diverse cellular functions such as polarity, cell-cell communication, neurological processes, kidney function, and a host of diseases including cancer and microbial infection. Additionally, MAGI-1 has undergone nomenclature changes in response to the discovery of an additional PDZ domain, leading to lack of continuity in the literature. We address the nomenclature of MAGI-1 as well as summarize many of the critical functions of the known interactions. Given the importance of many of the interactors, such as human papillomavirus E6, the Coxsackievirus and adenovirus receptor (CAR), and PTEN, the enhancement or disruption of MAGI-based interactions has the potential to affect cellular functions that can potentially be harnessed as a therapeutic strategy for a variety of diseases.

Ligand-of-Numb protein X1 controls the coxsackievirus B3-induced myocarditis via regulating the stability of coxsackievirus and adenovirus receptor.

Group B coxsackieviruses (CVBs) are the main cause of virus-induced myocarditis. CVBs use coxsackievirus and adenovirus receptor (CAR) for infection and targeting CAR has been shown to ameliorate CVBs-induced myocarditis. Ligand-of-Numb protein X1 (LNX1) is an E3 ubiquitin ligase that was shown to interact with CAR. However, the precise effect of LNX1 on CAR and the roles of LNX1 on CVBs-induced myocarditis remain unknown. In the present study, we generated mice deficient in LNX1 in the heart and evaluated the symptoms of myocarditis after CVB3 infection. We also monitored the expression and ubiquitination of CAR in LNX1-deficient cardiomyocytes after CVBs infection. We found that CVBs infection decreased CAR expression while promoted the expression of LNX1. Mice with deficiency of LNX1 in the heart had normal myocardial development while had deteriorated myocarditis symptoms after CVB3 infection. In LNX1-deficient cardiomyocytes, decreased ubiquitination of CAR and upregulation of CAR were observed after CVB3 infection. In summary, LNX1 controls CVB3-induced myocarditis by regulating the expression of CAR.

The Coxsackievirus and Adenovirus Receptor Has a Short Half-Life in Epithelial Cells.

The coxsackievirus and adenovirus receptor (CAR) is an essential cellular protein that is involved in cell adhesion, cell signaling, and viral infection. The 8-exon encoded isoform (CAREx8) resides at the apical surface of polarized epithelia, where it is accessible as a receptor for adenovirus entering the airway lumen. Given its pivotal role in viral infection, it is a target for antiviral strategies. To understand the regulation of CAREx8 and determine the feasibility of receptor downregulation, the half-life of total and apical localized CAREx8 was determined and correlated with adenovirus transduction. Total and apical CAREx8 has a relatively short half-life of approximately 2 h. The half-life of apical CAREx8 correlates well with adenovirus transduction. These results suggest that antiviral strategies that aim to degrade the primary receptor for apical adenovirus infection will be effective within a relatively short time frame after application.

Molecular basis of differential receptor usage for naturally occurring CD55-binding and -nonbinding coxsackievirus B3 strains

Receptor usage defines cell tropism and contributes to cell entry and infection. Coxsackievirus B (CVB) engages coxsackievirus and adenovirus receptor (CAR), and selectively utilizes the decay-accelerating factor (DAF; CD55) to infect cells. However, the differential receptor usage mechanism for CVB remains elusive. This study identified VP3-234 residues (234Q/N/V/D/E) as critical population selection determinants during CVB3 virus evolution, contributing to diverse binding affinities to CD55. Cryoelectron microscopy (cryo-EM) structures of CD55-binding/nonbinding isolates and their complexes with CD55 or CAR were obtained under both neutral and acidic conditions, and the molecular mechanism of VP3-234 residues determining CD55 affinity/specificity for naturally occurring CVB3 strains was elucidated. Structural and biochemical studies invitro revealed the dynamic entry process of CVB3 and the function of the uncoating receptor CAR with different pH preferences. This work provides detailed insight into the molecular mechanism of CVB infection and contributes to an in-depth understanding of enterovirus attachment receptor usage.