Decreased expression of GPC1 in human skin keratinocytes and epidermis during ageing.

BACKGROUND: Glypicans (GPCs) are heparan sulfate cell membrane proteoglycans containing glycosylphosphatidylinositol (GPI) anchor. They play important role in cell behavior by activating/presenting numerous growth factors and cytokines. OBJECTIVES: The expression of GPCs was investigated in primary culture of skin keratinocytes sampled from healthy donors of different age. MATERIALS AND METHODS: Primary keratinocytes from healthy female donors aged from 20 to 89 years old (n = 30) were either isolated from breast or abdominal skin samples (n = 27) or purchased (n = 3). GPCs expression was examined by qPCR, immunohistochemistry and western blot. Its role in proliferation induced by fibroblast growth factor 2 (FGF2) was also studied. RESULTS: Glypican 1 (GPC1) was the major expressed GPC in human keratinocytes. Its expression was up to two orders of magnitude higher than other GPCs and was significantly decreased with the age of the donors. It was localized at the cell surface and associated with intracellular granules. In skin sections, GPC1 was mainly localized in basal layer of epidermis. Shedding of GPCs decreased the proliferative effect of FGF2, confirming their role of modulator of growth factor effects on keratinocytes. These results established GPC1 as an important player in epidermis biology and skin ageing.

Lumican inhibits B16F1 melanoma cell lung metastasis.

BACKGROUND: Lumican is a small leucine-rich proteoglycan (SLRP) of the extracellular matrix (ECM) involved in the control of melanoma growth and invasion. The aim of the present study was to analyse the role of lumican in the regulation of the development of lung metastasis. METHODS: B16F1 melanoma cells stably transfected with lumican expressing plasmid (Lum-B16F1) were injected to syngenic mice. The lung metastasis was compared to mice injected with mock-transfected B16F1 cells (Mock-B16F1). The expression of lumican, cyclin D1, apoptotic markers, vascular endothelium growth factor (VEGF) and Von Willebrand Factor (vWF) within lung metastasis nodules was investigated by immunohistochemistry. In parallel, cells cultured in presence of lumican were assayed for apoptosis and motility. RESULTS: We observed that the number and the size of lung metastasis nodules were significantly decreased in mice injected with Lum-B16F1 cells in comparison to Mock-B16F1 cells. This was associated with an increase of tumour cell apoptosis within metastasis nodules but the cell proliferation rate remained constant in the two mice groups. In contrast, the VEGF immunostaining and the number of blood vessels within the lung metastasis nodules were decreased in the lumican-expressing tumours. In vitro, a significant decrease of apoptotic markers in wild type B16F1 cells incubated with increasing amounts of lumican core protein was observed. In addition, pseudotubes formation on Matrigel(R) and the migratory capacity of endothelial cells was inhibited by lumican. Altogether, our results indicate that lumican decreases lung metastasis development not only by inducing tumour cell apoptosis but also by inhibiting angiogenesis.

17Beta-oestradiol up-regulates the expression of a functional UDP-glucose dehydrogenase in articular chondrocytes: comparison with effects of cytokines and growth factors.

OBJECTIVES: To investigate the mechanisms by which cytokines and 17beta-oestradiol (17beta-E2) modulate gene expression and activity of uridine diphosphoglucose dehydrogenase (UGDH), a key enzyme of GAG synthesis in articular chondrocytes. METHODS: Rabbit articular chondrocytes (RAC) from 3-week-old animals were incubated for 24 h with TGF-beta, insulin like growth factor-I (IGF-I), IL-1beta, IL-6 and 17beta-E2. GAG synthesis was measured by [35S]-sulphate labelling and the expression of the UGDH gene was estimated by both real-time polymerase chain reaction and western blotting, whereas the enzyme activity was assayed by a spectrophotometric procedure. In addition, the transcriptional activity of several UGDH gene promoter constructs was determined in RAC transiently transfected with wild-type or deleted human oestrogen receptor-alpha gene (hER alpha66 or hER alpha46, respectively). RESULTS: 17Beta-E2 and its receptor hER alpha66 enhanced GAG neosynthesis in rabbit articular chondrocytes, as did TGF-beta1 whereas IL-1beta decreased this synthesis. 17Beta-E2 was found to exert positive regulatory effects at mRNA, protein and UGDH activity levels. In addition, the receptor hER alpha66, but not hER alpha46, increased the transcriptional activity of the UGDH gene. In contrast, no clear correlation between transcription, translation and activity of the UGDH was found under the effects of the cytokines studied. However, TGF-beta enhanced the enzyme activity, whereas IL-1beta, IL-6 and IGF-I were without significant effect. CONCLUSIONS: 17Beta-E2 enhanced GAG synthesis in chondrocytes via up-regulation of the UGDH gene expression and enzyme activity. These data provide insights into the molecular mechanisms involved in the regulation of the UGDH gene and offer new approaches to investigate its potential alteration in joint diseases.

Expression of lumican, a small leucine-rich proteoglycan with antitumour activity, in human malignant melanoma.

BACKGROUND: The family of small leucine-rich proteoglycans (SLRPs), which includes decorin, lumican, biglycan and fibromodulin, constitutes an abundant component of the skin extracellular matrix. We previously demonstrated that human lumican inhibits melanoma growth and progression in a mouse experimental model, by regulating cell migration, proliferation and apoptosis. AIM: The aim of this study was to investigate the expression of lumican and decorin in human malignant melanoma and adjacent peritumoral tissue, to understand better their role in the control of growth and invasion of human melanoma. METHODS: Expression of both proteoglycans was studied by immunohistochemistry using specific antibodies in 34 malignant melanomas, 12 Hutchinson's melanotic freckles and 4 cutaneous metastatic melanomas. RESULTS: We showed that lumican and decorin are located in the dermis and in the peritumoral stroma of malignant melanoma, but are not found in melanoma cells or dense tumour tissue. In the healthy dermis, distant from the tumour, the increasing ratio of lumican to decorin was inversely correlated with the proliferation of the tumour cells (P = 0.035). The comparison of the level of expression of lumican protein in superficial vs. nodular subtypes of malignant melanomas showed a decrease of lumican but not decorin in the peritumoral stroma of nodular subtypes. In the peritumoral stroma, the level of expression of lumican but not decorin decreased significantly (P = 0.016) with increasing Clark levels. In addition, immunocytochemical and reverse transcription PCR analyses of malignant melanoma cell lines (A-375, HT-144) and of MRC-5 and dermal fibroblasts from healthy donors in vitro confirmed that dermal fibroblasts are responsible for lumican and decorin synthesis in skin. CONCLUSIONS. Lumican may regulate vertical progression of human malignant melanoma, but further study is necessary to clarify the antitumour mechanism and the downstream signal transduction pathways involved.

Cell surface proteoglycan expression during maturation of human monocytes-derived dendritic cells and macrophages.

Cell surface proteoglycans play an important part in the functional and metabolic behaviour of leucocytes. We studied the expression of cell surface proteoglycans in human monocytes, in monocyte-derived immature and mature dendritic cells and in macrophages by metabolic labelling with [(35)S]-sulphate, reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. Immature dendritic cells had the highest metabolic activity for the synthesis of cell surface proteoglycans. The major part of these proteoglycans was in phosphatidylinositol-anchored form and was released after treatment with phospholipase C. A minor part was released by trypsin. Digestion with chondroitinase ABC and mild HNO(2) treatment showed that cell surface proteoglycans had a higher proportion of chondroitin sulphate, both in the phospholipase C and trypsin fractions, suggesting that at least some glypicans contained chondroitin sulphate chains. RT-PCR detected the transcripts of glypicans 1, 3, 4 and 5 and all syndecans. Immature dendritic cells expressed a most complex spectrum of glypicans and syndecans, glypican-1 and syndecan-1 being expressed preferentially by this type of cells. Mature dendritic cells expressed glypican-3, which was not present in other lineages. These results suggest that different mononuclear cells synthesize cell surface proteoglycans actively with characteristic expression of different syndecans and glypicans genes, depending on the degree of cell differentiation and/or maturation.

Expression of glycosaminoglycans and small proteoglycans in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(2+).

Glycyl-histidyl-lysine-Cu(2+) is a tripeptide-copper complex previously shown to be an activator of wound healing. We have investigated the effects of glycyl-histidyl-lysine-Cu(2+) on the synthesis of glycosaminoglycans and small proteoglycans in a model of rat experimental wounds and in rat dermal fibroblast cultures. Repeated injections of glycyl-histidyl-lysine-Cu(2+) (2 mg per injection) stimulated the wound tissue production, as appreciated by dry weight and total protein measurements. This stimulation was accompanied by an increased production of type I collagen and glycosaminoglycans (assessed, respectively, by hydroxyproline and uronic acid contents of the chamber). Electrophoretic analysis of wound tissue glycosaminoglycans showed an accumulation of chondroitin sulfate and dermatan sulfate in control wound chambers, whereas the proportion of hyaluronic acid decreased with time. The accumulation of chondroitin sulfate and dermatan sulfate was enhanced by glycyl-histidyl-lysine-Cu(2+) treatment. The expression of two small proteoglycans of the dermis, decorin and biglycan, was analyzed by northern blot. The biglycan mRNA steady-state level in the chamber was maximal at day 12, whereas the decorin mRNA increased progressively until the end of the experiment (day 22). Glycyl-histidyl-lysine-Cu(2+) treatment increased the mRNA level of decorin and decreased those of biglycan. In dermal fibroblast cultures, the stimulation of decorin expression by glycyl-histidyl-lysine-Cu(2+) was also found. In contrast, biglycan expression was not modified. These results show that the expression of different proteoglycans in wound tissue are regulated in a different manner during wound healing. The glycyl-histidyl-lysine-Cu(2+) complex is able to modulate the expression of the extracellular matrix macromolecules differently during the wound repair process.

Human UDP-glucose dehydrogenase gene: complete cloning and transcription start mapping.

UDP-glucose dehydrogenase (GDH) is an unique pathway enzyme, which furnishes in vertebrates the UDP-glucuronic acid for numerous transferases, including those of glycosaminoglycan synthesis and xenobiotics elimination. Using long and accurate PCR approach and searching the 5' cDNA-end sequences in public databases, we have cloned the human GDH gene. The gene contains 12 exons and spans over 26 kb. The first and eighth introns were not reported for mouse ortholog. Primer extension analysis identified the transcription start site 165 bases upstream from the translation initiation site. Most of the exons were interrupted on codon phase 0, confirming the conserved ancestral structure of the gene reported on the cDNA level.

Modulation of sulfated glycosaminoglycan and small proteoglycan synthesis by the extracellular matrix.

Cell culture in collagen lattice is known to be a more physiological model than monolayer for studying the regulation of extracellular matrix protein deposition. The synthesis of sulfated glycosaminoglycans (GAG) and dermatan sulfate (DS) proteoglycans by 3 cell strains were studied in confluent monolayers grown on plastic surface, in comparison to fully retracted collagen lattices. Cells were labelled with 35S-sulfate, followed by GAG and proteoglycan analysis by cellulose acetate and SDS-polyacrylamide gel electrophoresis, respectively. The 3 cell strains contracted the lattice in a similar way. In monolayer cultures, the major part of GAG was secreted into culture medium whereas in lattice cultures of dermal fibroblasts and osteosarcoma MG-63 cells but not fibrosarcoma HT-1080 cells, a higher proportion of GAGs, including dermatan sulfate, was retained within the lattices. Small DS proteoglycans, decorin and biglycan, were detected in fibroblasts and MG-63 cultures. They were preferentially trapped within the collagen gel. In retracted lattices, decorin had a higher Mr than in monolayer. Biglycan was detected in monolayer and lattice cultures of MG-63 cells but in lattice cultures only in the case of fibroblasts. In this last case, an up regulation of biglycan mRNA steady state level and down regulation of decorin mRNA was observed, in comparison to monolayers, indicating that collagen can modulate the phenotypical expression of small proteoglycan genes.

Triterpenes from Centella asiatica stimulate extracellular matrix accumulation in rat experimental wounds.

Titrated Extract from Centella asiatica (TECA) is a drug which has been used for many years in Europe for the treatment of wound healing defects. It is a reconstituted mixture of 3 triterpenes extracted from the plant, asiatic acid, madecassic acid and asiaticoside. In this report, we studied the effects of TECA and its separated components in the wound chamber model described by Schilling et al. Stainless steel wound chambers were surgically inserted under the skin of rats and received serial injections of either TECA or its purified components. Chambers were collected at days 7, 14, 21 or 28 for biochemical analysis or histological examination. TECA-injected wound chambers were characterized by increased dry weight, DNA, total protein, collagen and uronic acid contents. Peptidic hydroproline was also increased, showing an increased remodeling of the collagen matrix in the wound. The 3 purified components of TECA were all able to reproduce the effects of the complete drug, with some differences depending on the product. Asiatic acid and asiaticoside were the most active of the 3 triterpenes. Asiaticoside exerted a preferential stimulation of collagen synthesis and was active at low doses only. In addition to collagen, the 3 components were also able to stimulate glycosaminoglycan synthesis.

Biochemical alterations of uterine leiomyoma extracellular matrix in type IV Ehlers-Danlos syndrome.

Collagens and glycosaminoglycans were assessed in 6 leiomyomas from otherwise healthy ("control") patients and 1 leiomyoma from a patient with type IV Ehlers-Danlos syndrome. The type IV Ehlers-Danlos leiomyoma contained less type III collagen and dermatan sulfate than control leiomyomas. This might contribute to the formation of a defective collagen network in type IV Ehlers-Danlos syndrome.

Influence of transforming growth factor beta1 (TGF-beta1) on the behaviour of porcine thyroid epithelial cells in primary culture through thrombospondin-1 synthesis.

Transforming growth factor beta1 (TGF-beta1) is a secreted polypeptide that is thought to play a major role in the regulation of folliculogenesis and differentiation of thyroid cells. On porcine thyroid follicular cells cultured on plastic substratum, TGF-beta1, in a concentration-dependent way, promoted the disruption of follicles, cell spreading, migration and confluency by a mechanism that did not involve cell proliferation. TGF-beta1 strongly activated the production of thrombospondin-1 and (alpha)vbeta3 integrin in a concentration-dependent manner whereas the expression of thyroglobulin was unaffected. Anisomycin, an inhibitor of protein synthesis, inhibited the effect of TGF-beta1 on cell organization. Thrombospondin-1 reproduced the effect of TGF-beta1. In the presence of thrombospondin-1 cells did not organize in follicle-like structures but, in contrast, spreaded and reached confluency independently of cell proliferation. This effect is suppressed by an RGD-containing peptide. The adhesive properties of thrombospondin-1 for thyroid cells were shown to be mediated by both the amino-terminal heparin-binding domain and the RGD domain of thrombospondin-1. Adhesion was shown to involve (alpha)vbeta3 integrin. The results show that TGF-beta1 exerted an influence upon function and behaviour of follicle cells partly mediated by the synthesis of thrombospondin-1 and of its receptor (alpha)vbeta3 integrin.

Transforming growth factor beta-1 up-regulates clusterin synthesis in thyroid epithelial cells.

Porcine epithelial cells in primary culture seeded on plastic substratum form a monolayer containing pseudo-vesicles. When cultured in the presence of thyreotropin (TSH) thyrocytes adopted a follicular-like structure and formed clusters. Transforming growth factor beta-1 (TGFbeta1) induced a rapid spreading of the TSH-treated cells only. At the same time, TGFbeta1 enhanced clusterin protein and mRNA expression. The increase of clusterin synthesis was proportional to the TGFbeta1 concentration in the culture medium. Tunicamycin abolished the up-regulation of whole clusterin synthesis and morphological changes. The activator protein-1 binding site partly directed the TGFbeta1-stimulated clusterin expression. Phorbol ester caused rapid spreading of the cells with disappearance of vesicular and follicular structures. It decreased clusterin mRNA and protein expression, but increased Mr 45, 000 protein secretion in both TSH-treated and nontreated cells. Up-regulation of clusterin expression may be a marker of TGFbeta-mediated thyrocyte dedifferentiation.

Uridine diphosphoglucose dehydrogenase regulates proteoglycan expression: cDNA cloning and antisense study.

Using a reverse-transcriptase-polymerase chain reaction approach human and murine UDPG-dehydrogenase (GDH) was cloned from fibroblast mRNAs. Human enzyme is 97% and 27% identical with its murine and E. coli orthologs. Murine mRNA of 3.1 kb size is expressed in all the tissue studied at a level independent of glyceraldehyde-3-phosphate dehydrogenase (GADPH) mRNA. In human fibroblast in vitro, 2 GDH transcripts were observed. They were expressed proportionally to GAPDH. The simple pattern of human GDH Southern blotting suggests a single copy gene. An antisense oligonucleotide directed to the ATG region of the human enzyme inhibited 35S-sulphate incorporation into extracellular macromolecules, especially proteoglycans. These data indicate that GDH expression may regulate proteoglycan synthesis in the cells.

Alteration of matrix macromolecule synthesis by fibroblasts from a patient with pachydermoperiostosis.

Pachydermoperiostosis (primary hypertrophic osteoarthropathy) is a very rare genetic disease characterized by pachydermia, periostosis, arthralgia, and finger clubbing. Its pathophysiology is still unclear, but previous studies have reported connective tissue hypertrophy in the skin of these patients. We investigated the synthesis of collagen, fibronectin, and proteoglycans by fibroblasts from affected and unaffected skin from one patient with pachydermoperiostosis and four normal donors. We found that collagen synthesis was largely decreased in fibroblasts from the diseased skin, whereas the synthesis of the small dermatan-sulfate-containing proteoglycan decorin strongly increased. Fibroblasts from the unaffected skin of the patient exhibited syntheses of these macromolecules similar to control fibroblasts from healthy donors. Northern blot and dot blot analyses showed decreased pro alpha 1 (I) collagen in patient's affected and unaffected skin fibroblasts whereas increased decorin mRNA levels were found in fibroblasts from the patient's affected skin. No change in cell proliferation was observed. These data demonstrate an alteration of fibroblast biosynthetic activity in the skin lesions of pachydermoperiostosis, which may be responsible, at least in part, for the patient's phenotype.

The murine biglycan: complete cDNA cloning, genomic organization, promoter function, and expression.

Biglycan is a ubiquitous chondroitin/dermatan sulfate proteoglycan that belongs to a growing family of proteins harboring leucine-rich repeats. We have cloned and sequenced the cDNA containing the complete murine biglycan, elucidated its genomic organization, and demonstrated functional promoter activity of its 5' flanking region. The deduced biglycan protein core was highly conserved across species. However, the mouse biglycan (Bgn) gene was significantly larger than the human counterpart, primarily because of a large > 4.5-kb intron between exons 1 and 2. The mouse Bgn gene spanned over 9.5 kb of continuous DNA and comprised 8 exons, with a perfectly conserved intron/exon organization vis-á-vis the human counterpart. The promoter region was enriched in GC dinucleotide and contained numerous cis-acting elements including binding sites for SP-1, AP-1 and AP-2 factors. It lacked TATA and CAAT boxes typical of housekeeping genes. In support of this, primer extension analysis showed the existence of multiple transcription start sites. Transient cell transfection assays with a construct comprising the 548 bp upstream of the major transcription start site fused to the chloramphenicol acetyl transferase reporter gene showed functional promoter activity. Internal and 5' deletion constructs showed that the distal promoter of the Bgn gene was required for full transcriptional activity. In contrast to the homologous proteoglycan decorin, the highest expression of biglycan mRNA was observed in lung, liver, and spleen of adult mouse and the lowest in skin, heart, and kidney. These results will be useful for the study of biglycan gene regulation and for the generation of mice with targeted null mutation of the Bgn gene.

Glutamine increases collagen gene transcription in cultured human fibroblasts.

We have previously shown that glutamine stimulates the synthesis of collagen in human dermal confluent fibroblast cultures (Bellon, G. et al. [1987] Biochim. Biophys. Acta, 930, 39-47). In this paper, we examine the effects of glutamine on collagen gene expression. A dose-dependent effect of glutamine on collagen synthesis was demonstrated from 0 to 0.25 mM followed by a plateau up to 10 mM glutamine. Depending on the cell population, collagen synthesis was increased by 1.3-to 2.3-fold. The mean increase in collagen and non-collagen protein synthesis was 63% and 18% respectively. Steady-state levels of alpha 1(I) and alpha 1(III) mRNAs, were measured by hybridizing total RNA to specific cDNA probes at high stringency. Glutamine increased the steady-state level of collagen alpha 1(I) and alpha 1(III) mRNAs in a dose-dependent manner. At 0.15 mM glutamine, collagen mRNAs were increased by 1.7-and 2.3-fold respectively. Nuclear run-off experiments at this concentration of glutamine indicated that the transcriptional activity was increased by 3.4-fold for the pro alpha 1(I) collagen gene. The effect of glutamine on gene transcription was also supported by the measurement of pro alpha 1(I) collagen mRNA half-life since glutamine did not affect its stability. Protein synthesis seemed to be required for the glutamine-dependent induction of collagen gene expression since cycloheximide suppressed the activation. The effect of glutamine appeared specific because analogues and/or derivatives of glutamine, such as acivicin, 6-diazo-5-oxo-L-norleucine, homoglutamine, ammonium chloride and glutamate did not replace glutamine. The influence of amino acid transport systems through plasma membrane was assessed by the use of 2(methylamino)-isobutyric acid and beta 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid. The glutamine-dependent induction of collagen gene expression was found to be independent of transport system A but dependent on transport system L whose inhibition induced a decrease in pro alpha 1(I) collagen gene transcription by an unknown mechanism. Thus, glutamine, at physiological concentrations, indirectly regulates collagen gene expression.

Stimulation of sulphated glycosaminoglycan and decorin production in adult dermal fibroblasts by recombinant human interleukin-4.

Interleukin-4 (IL-4) is a pleiotropic cytokine expressed by inflammatory cells. Previous work from our laboratory has shown that it stimulates collagen synthesis in fibroblasts. Here we report the effects of recombinant human IL-4 on glycosaminoglycan (GAG) and proteoglycan synthesis in normal dermal fibroblasts from adult donors. IL-4 (10 and 100 units/ml) induced a dose-dependent increase of [3H]glucosamine and [35S]sulphate incorporation into total GAGs. The analysis of the different GAG fractions indicated the enhanced synthesis of dermatan/chondroitin sulphates. IL-4 had no effect on hyaluronan synthesis. The increase of sulphated GAG synthesis was correlated with an increase of proteoglycans in the culture medium. Decorin was identified as the major chondroitin/dermatan sulphate-containing proteoglycan in the culture medium of fibroblasts. Its synthesis was strongly stimulated by IL-4. Both the core-protein synthesis and mRNA expression were enhanced, indicating that the cytokine acted, at least in part, at the pre-translational level. These results indicate that IL-4 is able to modulate not only collagen, but also proteoglycan, production by human fibroblasts. Their implications in physiopathological processes such as wound healing or fibrosis is suggested.