Overexpression of Serpin Squamous Cell Carcinoma Antigens in Psoriatic Skin

Squamous cell carcinoma antigen belongs to the serpin family and is used for the diagnosis and management of squamous cell carcinoma. We investigated the involvement of squamous cell carcinoma antigen in psoriasis, as it is always detected in the sera of patients with psoriasis. Squamous cell carcinoma antigen localization in psoriatic epidermis varied depending on its concentration in the patient's sera. When its level was low in serum, weak and scattered staining was observed in the granular layer. With a high concentration of squamous cell carcinoma antigen, strong staining through the suprabasal to granular layer and condensed staining around the plasma membrane or intracellular space was detected in the affected epidermis. Interestingly, squamous cell carcinoma antigen was abundant in nuclei of the granular layer cells and elongated rete ridges. Immunoelectron microscopy confirmed the localization of squamous cell carcinoma antigen in the nuclei as well as in the periphery of the cell membrane. A cDNA library was constructed from psoriatic epidermis and both clones, SCCA1 and SCCA2, were obtained. Attempts to raise specific antibodies or to prepare cRNA probes for SCCA1 and SCCA2 were unsuccessful because of their nearly identical structures. A primer pair from each reactive site sequence enabled us to give a distinctive product for SCCA1 and SCCA2 by reverse transcription polymerase chain reaction. Analysis using these primers demonstrated that the SCCA2 transcript was specifically expressed in psoriatic skin tissues. Our results suggest that overexpression of squamous cell carcinoma antigens is associated with the disease activity of psoriasis

Syndecan-4 Is Essential for Development of Concentric Myocardial Hypertrophy via Stretch-Induced Activation of the Calcineurin-NFAT Pathway

Sustained pressure overload leads to compensatory myocardial hypertrophy and subsequent heart failure, a leading cause of morbidity and mortality. Further unraveling of the cellular processes involved is essential for development of new treatment strategies. We have investigated the hypothesis that the transmembrane Z-disc proteoglycan syndecan-4, a co-receptor for integrins, connecting extracellular matrix proteins to the cytoskeleton, is an important signal transducer in cardiomyocytes during development of concentric myocardial hypertrophy following pressure overload. Echocardiographic, histochemical and cardiomyocyte size measurements showed that syndecan-4−/− mice did not develop concentric myocardial hypertrophy as found in wild-type mice, but rather left ventricular dilatation and dysfunction following pressure overload. Protein and gene expression analyses revealed diminished activation of the central, pro-hypertrophic calcineurin-nuclear factor of activated T-cell (NFAT) signaling pathway. Cardiomyocytes from syndecan-4−/−-NFAT-luciferase reporter mice subjected to cyclic mechanical stretch, a hypertrophic stimulus, showed minimal activation of NFAT (1.6-fold) compared to 5.8-fold increase in NFAT-luciferase control cardiomyocytes. Accordingly, overexpression of syndecan-4 or introducing a cell-permeable membrane-targeted syndecan-4 polypeptide (gain of function) activated NFATc4 in vitro. Pull-down experiments demonstrated a direct intracellular syndecan-4-calcineurin interaction. This interaction and activation of NFAT were increased by dephosphorylation of serine 179 (pS179) in syndecan-4. During pressure overload, phosphorylation of syndecan-4 was decreased, and association between syndecan-4, calcineurin and its co-activator calmodulin increased. Moreover, calcineurin dephosphorylated pS179, indicating that calcineurin regulates its own binding and activation. Finally, patients with hypertrophic myocardium due to aortic stenosis had increased syndecan-4 levels with decreased pS179 which was associated with increased NFAT activation. In conclusion, our data show that syndecan-4 is essential for compensatory hypertrophy in the pressure overloaded heart. Specifically, syndecan-4 regulates stretch-induced activation of the calcineurin-NFAT pathway in cardiomyocytes. Thus, our data suggest that manipulation of syndecan-4 may provide an option for therapeutic modulation of calcineurin-NFAT signaling

Essential and separable roles for Syndecan-3 and Syndecan-4 in skeletal muscle development and regeneration

Syndecan-3 and syndecan-4 function as coreceptors for tyrosine kinases and in cell adhesion. Syndecan-3(-/-) mice exhibit a novel form of muscular dystrophy characterized by impaired locomotion, fibrosis, and hyperplasia of myonuclei and satellite cells. Explanted syndecan-3(-/-) satellite cells mislocalize MyoD, differentiate aberrantly, and exhibit a general increase in overall tyrosine phosphorylation. Following induced regeneration, the hyperplastic phenotype is recapitulated. While there are fewer apparent defects in syndecan-4(-/-) muscle, explanted satellite cells are deficient in activation, proliferation, MyoD expression, myotube fusion, and differentiation. Further, syndecan-4(-/-) satellite cells fail to reconstitute damaged muscle, suggesting a unique requirement for syndecan-4 in satellite cell function

Matrix Contraction by Dermal Fibroblasts Requires Transforming Growth Factor-β/Activin-Linked Kinase 5, Heparan Sulfate-Containing Proteoglycans, and MEK/ERK : Insights into Pathological Scarring in Chronic Fibrotic Disease

Scarring is characterized by excessive synthesis and contraction of extracellular matrix. Here, we show that fibroblasts from scarred (lesional) areas of patients with the chronic fibrotic disorder diffuse scleroderma [diffuse systemic sclerosis (dSSc)] show an enhanced ability to adhere to and contract extracellular matrix, relative to fibroblasts from unscarred (nonlesional) areas of dSSc patients and dermal fibroblasts from normal, healthy individuals. The contractile abilities of normal and dSSc dermal fibroblasts were suppressed by blocking heparin sulfate-containing proteoglycan biosynthesis or antagonizing transforming growth factor-β receptor type I [activin-linked kinase (ALK5)] or ras/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK). Compared with both normal and nonlesional fibroblasts, lesional dSSc fibroblasts overexpressed the heparin sulfate-containing proteoglycan syndecan 4. We also found that the procontractile signals from transforming growth factor (TGF)-β were integrated through syndecan 4 and MEK/ERK because the ability of TGFβ to induce contraction of dermal fibroblasts was prevented by MEK antagonism. TGFβ could not induce a contractile phenotype or phosphorylate ERK in syndecan 4(−/−) dermal fibroblasts. These results suggest that integrating TGFβ and ERK signals via syndecan 4 is essential for the contractile ability of dermal fibroblasts. We conclude that antagonizing MEK/ERK, TGFβ1/ALK5, or syndecan 4 may alleviate scarring in chronic fibrotic disease

Inhibition of pulmonary fibrosis in mice by CXCL10 requires glycosaminoglycan binding and syndecan-4

Pulmonary fibrosis is a progressive, dysregulated response to injury culminating in compromised lung function due to excess extracellular matrix production. The heparan sulfate proteoglycan syndecan-4 is important in mediating fibroblast-matrix interactions, but its role in pulmonary fibrosis has not been explored. To investigate this issue, we used intratracheal instillation of bleomycin as a model of acute lung injury and fibrosis. We found that bleomycin treatment increased syndecan-4 expression. Moreover, we observed a marked decrease in neutrophil recruitment and an increase in both myofibroblast recruitment and interstitial fibrosis in bleomycin-treated syndecan-4–null (Sdc4–/–) mice. Subsequently, we identified a direct interaction between CXCL10, an antifibrotic chemokine, and syndecan-4 that inhibited primary lung fibroblast migration during fibrosis; mutation of the heparin-binding domain, but not the CXCR3 domain, of CXCL10 diminished this effect. Similarly, migration of fibroblasts from patients with pulmonary fibrosis was inhibited in the presence of CXCL10 protein defective in CXCR3 binding. Furthermore, administration of recombinant CXCL10 protein inhibited fibrosis in WT mice, but not in Sdc4–/– mice. Collectively, these data suggest that the direct interaction of syndecan-4 and CXCL10 in the lung interstitial compartment serves to inhibit fibroblast recruitment and subsequent fibrosis. Thus, administration of CXCL10 protein defective in CXCR3 binding may represent a novel therapy for pulmonary fibrosis