Mapping of the Wnt/β-catenin/TCF response elements in the human versican promoter

Type I Interferon Signaling Increases Versican Expression and Synthesis in Lung Stromal Cells During Influenza Infection

Versican, a chondroitin sulfate proteoglycan, is an essential component of the extracellular matrix (ECM) in inflammatory lung disease. Versican's potential as an immunomodulatory molecule makes it a promising therapeutic target for controlling host immune responses in the lungs. To establish changes to versican expression and accumulation during influenza A viral pneumonia, we document the temporal and spatial changes to versican mRNA and protein in concert with pulmonary inflammatory cell infiltration. These studies were performed in the lungs of wild-type C57BL6/J mice on days 3, 6, 9, and 12 post-infection with influenza A virus using immunohistochemistry, in situ hybridization, and quantitative digital pathology. Using duplex in situ hybridization, we demonstrate that type I interferon signaling contributes significantly to versican expression in lung stromal cells. Our findings show that versican is a type I interferon-stimulated gene in pulmonary fibroblasts and pericytes in the context of viral pneumonia. These data also provide a guide for future studies to determine the role of versican in the pulmonary immune response to influenza infection.

The extracellular matrix as modifier of neuroinflammation and remyelination in multiple sclerosis

Remyelination failure contributes to axonal loss and progression of disability in multiple sclerosis. The failed repair process could be due to ongoing toxic neuroinflammation and to an inhibitory lesion microenvironment that prevents recruitment and/or differentiation of oligodendrocyte progenitor cells into myelin-forming oligodendrocytes. The extracellular matrix molecules deposited into lesions provide both an altered microenvironment that inhibits oligodendrocyte progenitor cells, and a fuel that exacerbates inflammatory responses within lesions. In this review, we discuss the extracellular matrix and where its molecules are normally distributed in an uninjured adult brain, specifically at the basement membranes of cerebral vessels, in perineuronal nets that surround the soma of certain populations of neurons, and in interstitial matrix between neural cells. We then highlight the deposition of different extracellular matrix members in multiple sclerosis lesions, including chondroitin sulphate proteoglycans, collagens, laminins, fibronectin, fibrinogen, thrombospondin and others. We consider reasons behind changes in extracellular matrix components in multiple sclerosis lesions, mainly due to deposition by cells such as reactive astrocytes and microglia/macrophages. We next discuss the consequences of an altered extracellular matrix in multiple sclerosis lesions. Besides impairing oligodendrocyte recruitment, many of the extracellular matrix components elevated in multiple sclerosis lesions are pro-inflammatory and they enhance inflammatory processes through several mechanisms. However, molecules such as thrombospondin-1 may counter inflammatory processes, and laminins appear to favour repair. Overall, we emphasize the crosstalk between the extracellular matrix, immune responses and remyelination in modulating lesions for recovery or worsening. Finally, we review potential therapeutic approaches to target extracellular matrix components to reduce detrimental neuroinflammation and to promote recruitment and maturation of oligodendrocyte lineage cells to enhance remyelination.

The Canonical Wnt Signaling (Wnt/β-Catenin Pathway): A Potential Target for Cancer Prevention and Therapy

Precise regulation of signal transduction pathways is crucial for normal animal development and for maintaining cellular and tissue homeostasis in adults. The Wnt/Frizzled-mediated signaling includes canonical and non-canonical signal transduction pathways. Upregulation or downregulation of the canonical Wnt signaling (or the Wnt/β-Catenin signal transduction) leads to a variety of human diseases, including cancers, neurodegenerative disorders, skin and bone diseases, and heart deficiencies. Therefore, Wnt/β-Catenin signal transduction is a potential clinical target for the treatment of not only human cancers but also some other human chronic diseases. Here, some recent results including those from my laboratory highlighting the role of Wnt/β-Catenin signal transduction in human cancers will be reviewed. After a brief overview on canonical Wnt signaling and introducing some critical β-Catenin/T-cell factor-target genes, the interaction of canonical Wnt signaling with some common human cancers will be discussed. In the end, the different segments of the aforesaid signaling pathway, which have been considered as targets for clinical purposes, will be scrutinized.

Versican-A Critical Extracellular Matrix Regulator of Immunity and Inflammation

The extracellular matrix (ECM) proteoglycan, versican increases along with other ECM versican binding molecules such as hyaluronan, tumor necrosis factor stimulated gene-6 (TSG-6), and inter alpha trypsin inhibitor (IαI) during inflammation in a number of different diseases such as cardiovascular and lung disease, autoimmune diseases, and several different cancers. These interactions form stable scaffolds which can act as "landing strips" for inflammatory cells as they invade tissue from the circulation. The increase in versican is often coincident with the invasion of leukocytes early in the inflammatory process. Versican interacts with inflammatory cells either indirectly via hyaluronan or directly via receptors such as CD44, P-selectin glycoprotein ligand-1 (PSGL-1), and toll-like receptors (TLRs) present on the surface of immune and non-immune cells. These interactions activate signaling pathways that promote the synthesis and secretion of inflammatory cytokines such as TNFα, IL-6, and NFκB. Versican also influences inflammation by interacting with a variety of growth factors and cytokines involved in regulating inflammation thereby influencing their bioavailability and bioactivity. Versican is produced by multiple cell types involved in the inflammatory process. Conditional total knockout of versican in a mouse model of lung inflammation demonstrated significant reduction in leukocyte invasion into the lung and reduced inflammatory cytokine expression. While versican produced by stromal cells tends to be pro-inflammatory, versican expressed by myeloid cells can create anti-inflammatory and immunosuppressive microenvironments. Inflammation in the tumor microenvironment often contains elevated levels of versican. Perturbing the accumulation of versican in tumors can inhibit inflammation and tumor progression in some cancers. Thus versican, as a component of the ECM impacts immunity and inflammation through regulating immune cell trafficking and activation. Versican is emerging as a potential target in the control of inflammation in a number of different diseases.

Cloning and characterization of the LEF/TCF gene family in grass carp (Ctenopharyngodon idella) and their expression profiles in response to grass carp reovirus infection

T-cell factor/lymphoid enhancer-binding factor (TCF/LEF) proteins from the High Mobility Group (HMG) box family act as the main downstream effectors of the Wnt signaling pathway. HMGB proteins play multifaceted roles in the immune system of mammals. To clarify the immunological characteristics of LEF/TCF genes in grass carp (Ctenopharyngodon idella), five LEF/TCF genes (TCF7, LEF1, TCF7L1A, TCF7L1B, and TCF7L2) were identified and characterized. All five LEF/TCF proteins contained two characteristic domains: a HMG-BOX domain and a CTNNB1_binding region. Phylogenetic tree analysis revealed that the LEF/TCF proteins were represented different lineages. These results of subcellular localization showed that four of the LEF/TCF genes were localized exclusively within the nucleus, while TCF7L2 was localized in the cytoplasm and nucleus. The mRNA expression profiles of these LEF/TCF family genes differed across different tissues. The mRNA expression levels of TCF7, TCF7L1A, and TCF7L2 changed significantly in liver after grass carp reovirus (GCRV) challenge; TCF7 and TCF7L1A responded early while TCF7L2 responded late. This suggests that these genes may participate in GCRV-related immune responses. Moreover, TCF7 promoted Bcl6 transcription in response to the GCRV challenge. These findings further our understanding of the function of LEF/TCF genes in teleosts.

Proteoglycans as Immunomodulators of the Innate Immune Response to Lung Infection

Proteoglycans (PGs) are complex, multifaceted molecules that participate in diverse interactions vital for physiological and pathological processes. As structural components, they provide a scaffold for cells and structural organization that helps define tissue architecture. Through interactions with water, PGs enable molecular and cellular movement through tissues. Through selective ionic interactions with growth factors, chemokines, cytokines, and proteases, PGs facilitate the ability of these soluble ligands to regulate intracellular signaling events and to influence the inflammatory response. In addition, recent findings now demonstrate that PGs can activate danger-associated molecular patterns (DAMPs) and other signaling pathways to influence production of many of these soluble ligands, indicating a more direct role for PGs in influencing the immune response and tissue inflammation. This review will focus on PGs that are selectively expressed during lung inflammation and will examine the novel emerging concept of PGs as immunomodulatory regulators of the innate immune responses in lungs.

Versican is produced by Trif- and type I interferon-dependent signaling in macrophages and contributes to fine control of innate immunity in lungs

Growing evidence suggests that versican is important in the innate immune response to lung infection. Our goal was to understand the regulation of macrophage-derived versican and the role it plays in innate immunity. We first defined the signaling events that regulate versican expression, using bone marrow-derived macrophages (BMDMs) from mice lacking specific Toll-like receptors (TLRs), TLR adaptor molecules, or the type I interferon receptor (IFNAR1). We show that LPS and polyinosinic-polycytidylic acid [poly(I:C)] trigger a signaling cascade involving TLR3 or TLR4, the Trif adaptor, type I interferons, and IFNAR1, leading to increased expression of versican by macrophages and implicating versican as an interferon-stimulated gene. The signaling events regulating versican are distinct from those for hyaluronan synthase 1 (HAS1) and syndecan-4 in macrophages. HAS1 expression requires TLR2 and MyD88. Syndecan-4 requires TLR2, TLR3, or TLR4 and both MyD88 and Trif. Neither HAS1 nor syndecan-4 is dependent on type I interferons. The importance of macrophage-derived versican in lungs was determined with LysM/Vcan-/- mice. These studies show increased recovery of inflammatory cells in the bronchoalveolar lavage fluid of poly(I:C)-treated LysM/Vcan-/- mice compared with control mice. IFN-β and IL-10, two important anti-inflammatory molecules, are significantly decreased in both poly(I:C)-treated BMDMs from LysM/Vcan-/- mice and bronchoalveolar lavage fluid from poly(I:C)-treated LysM/Vcan-/- mice compared with control mice. In short, type I interferon signaling regulates versican expression, and versican is necessary for type I interferon production. These findings suggest that macrophage-derived versican is an immunomodulatory molecule with anti-inflammatory properties in acute pulmonary inflammation.

Wnt signaling pathway in cardiac fibrosis: New insights and directions

OBJECTIVE

Wnt signaling pathway significantly participates in cardiac fibrosis and CFs activation. Therefore, we reviewed current evidence on the new perspectives and biological association between Wnt signaling pathway and cardiac fibrosis.

DESIGN AND METHODS

A PubMed database search was performed for studies of Wnt signaling pathway in cardiac fibrosis and CFs activation.

RESULTS

Numerous studies have shown that the Wnt signaling pathway significantly participates in cardiac fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the Wnt signaling pathway significantly participating in cardiac fibrosis and CFs activation, and look ahead on new perspectives of Wnt signaling pathway research. Moreover, we will discuss the different insights that interact with the Wnt signaling pathway-regulated cardiac fibrosis. The Wnt proteins are glycoproteins that bind to the Fz receptors on the cell surface, which lead to several important biological functions, such as cell differentiation and proliferation. There are several signals among the characterized pathways of cardiac fibrosis, including Wnt/β-catenin signaling. In this review, new insight into the Wnt signaling pathway in cardiac fibrosis pathogenesis is discussed, with special emphasis on Wnt/β-catenin.

CONCLUSION

It seems reasonable to suggest the potential targets of Wnt signaling pathway and it can be developed as a therapeutic target for cardiac fibrosis.

Versican in inflammation and tissue remodeling: the impact on lung disorders

Versican is a proteoglycan that has many different roles in tissue homeostasis and inflammation. The biochemical structure comprises four different types of the core protein with attached glycosaminoglycans (GAGs) that can be sulfated to various extents and has the capacity to regulate differentiation of different cell types, migration, cell adhesion, proliferation, tissue stabilization and inflammation. Versican's regulatory properties are of importance during both homeostasis and changes that lead to disease progression. The GAGs that are attached to the core protein are of the chondroitin sulfate/dermatan sulfate type and are known to be important in inflammation through interactions with cytokines and growth factors. For a more complex understanding of versican, it is of importance to study the tissue niche, where the wound healing process in both healthy and diseased conditions take place. In previous studies, our group has identified changes in the amount of the multifaceted versican in chronic lung disorders such as asthma, chronic obstructive pulmonary disease, and bronchiolitis obliterans syndrome, which could be a result of pathologic, transforming growth factor β driven, on-going remodeling processes. Reversely, the context of versican in its niche is of great importance since versican has been reported to have a beneficial role in other contexts, e.g. emphysema. Here we explore the vast mechanisms of versican in healthy lung and in lung disorders.

Versican and the regulation of cell phenotype in disease

BACKGROUND

Versican is an extracellular matrix (ECM) proteoglycan that is present in the pericellular environment of most tissues and increases in many different diseases. Versican interacts with cells to influence the ability of cells to proliferate, migrate, adhere and assemble an ECM.

SCOPE OF REVIEW

The structure of the versican molecule is briefly reviewed and studies highlighting those factors that promote versican synthesis and degradation and their impact on cell phenotype in disease are discussed. Particular attention is given to vascular disease, but other diseases where versican is important are covered as well, most notably different forms of cancers. Attention is given to mechanisms(s) by which versican influences cell behaviors through either direct or indirect processes. Versican produced by either stromal cells or myeloid cells can have a major impact influencing immunity and inflammation. Finally, studies controlling versican accumulation that either delay or inhibit the progression of disease will be highlighted.

MAJOR CONCLUSIONS

Versican is one component of the ECM that can influence the ability of cells to proliferate, migrate, adhere, and remodel the ECM. Targeting versican as a way to control cell phenotype offers a novel approach in the treatment of disease.

SIGNIFICANCE

ECM molecules such as versican contribute to the structural integrity of tissues and interact with cells through direct and indirect means to regulate, in part, cellular events that form the basis of disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Galectin-3 accelerates the progression of oral tongue squamous cell carcinoma via a Wnt/β-catenin-dependent pathway

The purpose of this study was to elucidate the clinicopathological significance and mechanism of action of galectin-3 in oral tongue squamous cell carcinoma (OTSCC). Here, the expression of galectin-3 was quantified in OTSCC (n = 68) and paired OTSCC and normal surrounding tissues (n = 10) using immunohistochemical staining. Tca8113 OTSCC cells were transfected with a plasmid expressing galectin-3 cDNA or siRNA against galectin-3. Cell proliferation, migration and invasion were measured using the MTT assay, Matrigel-coated Transwell migration assay and wound healing assay. The effect of galectin-3 on the Wnt/β-catenin signaling pathway and epithelial mesenchymal transition (EMT) were investigated using a plasmid expressing the Wnt antagonist dickkopf 1 (DKK1) and Western blotting. Galectin-3 was expressed at significantly higher levels in OTSCC than the normal adjacent tissues; galectin-3 expression correlated strongly with pathological stage, pathological grade and lymph node invasion in OTSCC. Overexpression of galectin-3 promoted Tca8113 cell proliferation, migration and invasion, upregulated Wnt protein expression, activated β-catenin and induced the EMT; knockdown of galectin-3 had the opposite effects. Co-transfection of Tca8113 cells overexpressing galectin-3 with the Wnt antagonist DKK1 reduced the ability of galectin-3 to increase cell proliferation, migration and invasion, reduced upregulation of Wnt, inhibited β-catenin activation and abrogated the EMT, demonstrating that the Wnt/β-catenin signaling pathway mediated the effects of galectin-3. Galectin-3 plays an important role in the progression of OTSCC via activation of the Wnt/β-catenin signaling pathway.

Impact of laminitis on the canonical Wnt signaling pathway in basal epithelial cells of the equine digital laminae

The digital laminae is a two layer tissue that attaches the distal phalanx to the inner hoof wall, thus suspending the horse's axial skeleton in the hoof capsule. This tissue fails at the epidermal:dermal junction in laminitic horses, causing crippling disease. Basal epithelial cells line the laminar epidermal:dermal junction, undergo physiological change in laminitic horses, and lose versican gene expression. Versican gene expression is purportedly under control of the canonical Wnt signaling pathway and is a trigger for mesenchymal-to-epithelial transition; thus, its repression in laminar epithelial cells of laminitic horses may be associated with suppression of the canonical Wnt signaling pathway and loss of the epithelial cell phenotype. In support of the former contention, we show, using laminae from healthy horses and horses with carbohydrate overload-induced laminitis, quantitative real-time polymerase chain reaction, Western blotting after sodium dodecylsulfate polyacrylamide gel electrophoresis, and immunofluorescent tissue staining, that positive and negative regulatory components of the canonical Wnt signaling pathway are expressed in laminar basal epithelial cells of healthy horses. Furthermore, expression of positive regulators is suppressed and negative regulators elevated in laminae of laminitic compared to healthy horses. We also show that versican gene expression in the epithelial cells correlates positively with that of β-catenin and T-cell Factor 4, consistent with regulation by the canonical Wnt signaling pathway. In addition, gene and protein expression of β-catenin correlates positively with that of integrin β4 and both are strongly suppressed in laminar basal epithelial cells of laminitic horses, which remain E-cadherin⁺/vimentin⁻, excluding mesenchymal transition as contributing to loss of the adherens junction and hemidesmosome components. We propose that suppression of the canonical Wnt signaling pathway, and accompanying reduced expression of β catenin and integrin β4 in laminar basal epithelial cells reduces cell:cell and cell:basement membrane attachment, thus, destabilizing the laminar epidermal:dermal junction.