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B Nusgens

Publications and source records attributed to B Nusgens.

17 recordsLinked to original sources
PubMed1992

Modulation of collagen and fibronectin synthesis in fibroblasts by normal and malignant cells.

The influence of various normal and malignant human cells on the level of collagen synthesis by human fibroblasts was tested in coculture. As revealed by immunoperoxidase staining, in cocultures with breast adenocarcinoma cells (MCF7, SA52, T47D) fibroblasts synthesized collagen while tumor cells did not. Fibroblasts displayed increased collagen production without change in the overall protein synthesis. Several other types of cells derived from normal human tissues (keratinocytes, normal mammary cells) or from fibrosarcoma, melanoma, cervical carcinoma, choriocarcinoma, or other breast adenocarcinoma (SW613, MDA, BT20) did not affect collagen synthesis of fibroblasts. Although to a lesser extent, this stimulating effect was reproduced by using the conditioned medium (CM) of the active cells but not with CM of the other cell types. A slight stimulation was also obtained when tumoral MCF7 cells and fibroblasts shared the same medium but were physically separated, suggesting that close contact was required for optimal stimulation of collagen synthesis. The collagen synthesis stimulating activity was not related to a modification of fibroblast proliferation rate. The production of collagen types I, III, and VI and fibronectin were increased in cocultures of fibroblasts with MCF7 cells. The increased synthesis of collagen types I and III and fibronectin was paralleled by similar changes in the steady-state level of their mRNAs. On the contrary, the increased production of collagen type VI appeared regulated at a post-transcriptional level.

Adenocarcinoma↗
PubMed1992

The stimulation of fibroblasts' collagen synthesis by neoplastic cells is modulated by the extracellular matrix.

Human fibroblasts cocultured with neoplastic MCF7 cells produce increased amounts of collagen. A maximal stimulation requires direct cell-cell contacts between tumor cells and fibroblasts. However, this effect could be reproduced, although to a lesser extent, by medium conditioned by MCF7 cells, suggesting that it is mediated by a factor produced by MCF7 cells and secreted, at least partly, under a soluble form (Noël et al., 1992). This Collagen Stimulating Factor ("COSF") present in the culture medium displayed a molecular mass between 3,500 to 10,000 daltons, bound to heparin and appeared to be different from the growth factors described until now. The "COSF" can be released from the surface of MCF7 cells by treatment with heparin. The aim of the present work was to investigate the influence of various extracellular matrix components on the production and the release of "COSF". A 3- to 4-fold enhancement of collagen synthesis was observed in coculture on plastic and collagen type I substrates without significant modification of the non-collagen proteins. The increased collagen synthesis was paralleled by an elevation of specific collagen mRNAs level suggesting a regulation at a pretranslational level. On the opposite, in the presence of soluble or insoluble laminin, this stimulation was abolished. Similarly, coculture on "reconstituted basement membrane matrix", matrigel, did not increase collagen production. The "COSF" was found to bind to matrigel and could be released from the basement membrane matrix by treatment with heparin.

Adenocarcinoma↗
PubMed1991

Factor XIII of blood coagulation decreases the susceptibility of collagen precursors to proteolysis.

Factor XIII, the transglutaminase of blood coagulation, was found to reduce the susceptibility of collagen precursors synthesized by skin fibroblasts in vitro to proteolytic activity. Several hypotheses for the mechanism of action of FXIII are proposed. One of them is the self-association of collagen precursors as well as their association with other proteins present in the serum or synthesized by fibroblasts to form a high molecular weight complex. This complex contains, among others, collagen I and partially processed precursors (alpha 1, alpha 2, pN-alpha 1, and pN-alpha 2 chains), collagen III and its precursors (alpha 1 and pN-alpha 1 chains), fibronectin and FXIII. This study indicates that FXIII modifies the structural organisation of the synthesized products of fibroblasts and may partially protect them against proteolytic degradation.

Animals↗
PubMed1991

Altered response of progeria fibroblasts to epidermal growth factor.

The Hutchinson-Gilford syndrome (progeria) is a rare disorder in childhood characterized by premature and accelerated aging. This study reports the effect of a potent growth factor, EGF, on the proliferative capacities and extracellular matrix macromolecules and collagenase expression of two strains of progeria skin-derived cells. At low population doubling levels (PDL less than 10), confluent cultures of progeria fibroblasts made quiescent by lowering the concentration of serum in the medium did not respond to EGF while the mitotic activity of normal PDL-matched fibroblasts was almost maximally restored upon addition of EGF. No obvious difference between normal and low PDL progeria fibroblasts was observed in the number and in the affinity of the receptors measured by [125I]EGF binding. The synthesis of collagen and non-collagen proteins was similar in normal and affected cells at low and high serum concentration and both types of cells responded to EGF by a specific inhibition of collagen synthesis. Besides a normal level of mRNA coding for type I and type III collagens, collagenase and laminin, progeria fibroblasts expressed a high level of elastin and type IV collagen mRNA. Like normal fibroblasts, progeria cells responded to EGF by a decrease in the level of mRNA for fibrillar collagens and elastin. In contrast, a complete lack of response to EGF was observed for collagenase mRNA whereas the expression of this enzyme was strikingly induced by EGF in normal PDL-matched cells. The abnormal expression of type IV collagen was not significantly modified by EGF. At PDL greater than 10, progeria cells exhibited features of senescence. A significant reduction of collagen synthesis was observed and no further inhibition by EGF was recorded.

Cell Division↗
PubMed1991

Abnormal gene expression in skin fibroblasts from a Hutchinson-Gilford patient.

We had the opportunity to investigate a new case of Hutchinson-Gilford progeria, a rare disease commonly regarded as a model in the study of aging. Two strains of fibroblasts (strains 1 and 2) were derived from two pieces of a skin biopsy. These two populations multiplied as normal cells at low population doubling level but senesced rapidly and stopped proliferating after 14 or 15 population doubling levels. Interestingly, an unusual pattern of growth in clusters was observed for strain 1. The level of collagen and noncollagen protein synthesis of both strains of affected fibroblasts was similar to that of normal fibroblasts as determined by [3H]proline incorporation measurement and was similarly affected by varying serum concentrations. The pattern of the main types of newly synthesized collagen polypeptides analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was similar in normal and progeria cells. The steady-state level of mRNAs coding for macromolecules of the extracellular matrix did not provide any differences between affected and control fibroblasts except for a strong increase of elastin and of alpha 1 and alpha 2 type IV procollagen mRNA mainly in strain 1 and less marked in strain 2. Interestingly, senescent progeria fibroblasts exhibited a reduced level of all the tested mRNAs, whereas collagen type IV and elastin mRNAs remained elevated. As suggested by immunofluorescence and immunoblotting studies, the increased amount of type IV mRNAs was paralleled by an enhanced production of type IV collagen by fibroblasts in vitro. Histologic examination of the skin revealed a superabundant network of abnormal elastic fibers in the reticular dermis and a thickening of basement membranes. The relationship between these alterations and aging in progeria is discussed.

Child↗
PubMed1990

C1q, a collagen-like complement subcomponent, in dermatosparactic cattle: its extracellular modification is not affected by lack of procollagen N-terminal proteinase (pN-proteinase).

C1q, a collagen-like complement protein, was purified from the serum of a dermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum C1q from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from the dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No difference, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and tryptic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q.

Animals↗
PubMed1990

Response to epidermal growth factor of skin fibroblasts from donors of varying age is modulated by the extracellular matrix.

The present study was undertaken to investigate the effect of epidermal growth factor (EGF) on the biosynthetic activity of skin fibroblasts from donors of varying age and the modulation of their response to this growth factor by culture in a three-dimensional extracellular matrix. When cultured in monolayer on plastic or at the surface of a collagen gel, EGF specifically inhibited collagen synthesis whatever the age of the donor (from 17 to 84 years, n = 11). This inhibition was paralleled by a significant decrease in the steady-state level of procollagen type I mRNAs. When embedded in a three-dimensional floating collagen lattice, EGF stimulated the non-collagen protein (NCP) synthesis in fibroblasts from younger donors (5 out of 6) while fibroblasts from the older ones were not affected. Collagen production by fibroblasts from younger donors was not inhibited as in monolayer (some being even stimulated) while that of the older donors was inhibited as observed in monolayer. The steady-state level of procollagen type I mRNA was not modified by EGF in the three-dimensional culture. No significant difference was observed in the affinity and the number of EGF receptors of the fibroblasts on plastic or embedded in a collagen lattice between young and aged donors. Our results suggest that the environment of the cells can modulate the reactivity to EGF and reveal differences related to in vivo aging.

Adolescent↗
PubMed1990

Radioimmunoassay for human type II collagen.

Human articular cartilage type II collagen (h coll.II) was purified and used to develop a radioimmunoassay. The sequential saturation procedure allowed a sensitivity of 3 ng/tube. The intra and between assay coefficients of variation were less than 10 and 20% respectively in the linear part of the curve. The assay was highly specific for native human articular type II collagen. There was no cross-reactivity with other constituents of cartilage: human proteoglycans, fibronectin, laminin and hyaluronic acid did not interfere with the assay. No cross-reactivity existed with bovine collagen types I, III, IV. However, native collagens from human placenta (I, III, IV, V, VI), rat and calf skin type I collagens and bovine type II collagen produced a weak cross-reaction only at high doses. Concerning the latter, inhibition curves were not parallel. Parallelism of inhibition curves were observed for dilution of type II collagen, produced by human chondrocytes in three-dimensional culture. All of these characteristics indicate that radioimmunoassy of type II collagen is a very sensitive and specific method available for the study and quantification of type II collagen in in vitro experimental conditions.

Cartilage, Articular↗
PubMed1990

Retinoic acid inhibits the production of collagenase by human epidermal keratinocytes.

Lattices made of collagen and fibroblasts can be used as dermal equivalents to grow human keratinocytes in vitro. When these cultures are performed in a medium containing delipidized serum, the lattice is eventually degraded by the growing epithelium. The digestion of the dermal equivalent is due to the secretion of a collagenase by the keratinocytes. This degradation does not occur in cultures containing total serum or supplemented with retinoic acid. We show in this paper that retinoic acid inhibits the secretion of this keratinocyte collagenase in a dose-dependent manner. In the light of this result, the possible involvement of collagenase inhibition in the therapeutic effect of retinoic acid in skin disorders and skin aging must be considered.

Blood Physiological Phenomena↗
PubMed1990

Factor XIII in scleroderma: in vitro studies.

The administration of Factor XIII (FXIII) produces a beneficial effect on the skin lesions in about 50% of the treated patients with progressive systemic sclerosis (PSS). The effect of FXIII on various skin fibroblast functions (proliferation, attachment, biosynthetic activity and mechanical properties) was investigated in vitro using normal and PSS strains. In cell culture, most of the PSS fibroblast strains synthesized excessive amounts of collagen. Other cell functions such as adhesion to collagen I or III, to fibronectin, retraction of collagen lattices, proliferation in low serum concentration and degradation of newly synthesized collagen were not significantly different. The addition of FXIII (I U/ml) inhibited the synthesis of collagen by normal fibroblasts and reduced it in PSS fibroblasts to a level similar to that of normal fibroblasts. This effect was observed for cells cultured on plastic or in a collagen lattice. In the latter, an increased amount of collagen degradation was observed. No significant effect of FXIII on the other cell functions was noted. Excessive collagen production by PSS fibroblasts can be repressed by FXIII in vitro by at least two distinct mechanisms: a reduction of collagen synthesis and an increased degradation of the newly synthesized collagen.

Adult↗
PubMed1977

Interaction between collagen type I and type III in conditioning bundles organization.

Type I and type III collagen extracted from skin was purified by differential salt precipitation and chromatography. By heating to 37 degrees, type I formed after a lag phase a floppy and opalescent gel of high optical density and type III formed more rapidly a translucent and rigid gel of low optical density. Addition of type III to type I resulted in formation of gels of reduced optical density and lag phase related to the proportion of type III added. Phase contrast and scanning electronmicroscopy demonstrated the formation of thick bundles of type I, thin fibers of type III and bundles of intermediate size related to the proportion of type III. The relationship between collagen type and bundle architecture might prove most significant in conditioning the mechanical properties of the connective tissues in normal and pathological conditions.

Amino Acids↗
PubMed1976

Bone in dermatosparaxis. I. Morphologic analysis.

Normal (N-) calf bone consists of lamellae regularly spaced and oriented parallel to the periosteum. The lamellae increase in thickness from the periosteum to the medullary cavity, by apposition of layers of cells and a calcifying matrix on either side of a hypercalcified primer. In the dermatosparactic (D-) bone, the hypercalcified primer is barely visible and the cells are irregularly arranged within the lamellae. The poorly defined vascular spaces are partly filled with an acellular calcified material. In the D-bone, the collagen fibers are sparse and radiate from the vascular space, while in the N-bone they are abundant and laid down concentric with the blood channels. In the D-bone, only a few weeks old, the outer lamellae are radially oriented with respect to the medullar cavity, while haversian remodeling already occurs in the inner part of the diaphysis. At 6 months, the inner half of the diaphysis is made up of normal haversian secondary bone, while the outer half is made up of radial lamellae. The alteration of the mechanical properties of procollagen fibers in the D-bone might be responsible for its defective organization. A resistant fibrous framework, therefore, seems required to ensure the spatial organization of the cells in the calcifying matrix and to maintain its cohesion.

Age Factors↗
PubMed1976

Bone in dermatosparaxis. II. Chemical analysis.

Physical and chemical analysis of the organic matrix of dermatosparactic (D-) bone was performed to evaluate the implication of an alteration in the mechanical properties of procollagen fibers in the process of calcification. The D-diaphyseal bone contained less collagen and more hydroxyapatite than normal (N-) calf bone. Fractionated by centrifugation in a density gradient, D-bone was found to be composed of more than 80% weight of a highly calcified fraction while N-bone of the same age contained only 37% of this fraction. As compared to N-bone, the amount of organic matrix per unit volume of D-bone was increased in the least calcified fractions and reduced in the most mineralized ones. The newly formed matrix of D-bone contained an amount of collagen similar to the N-bone while the concentration of other glycoproteins was higher. Calcification was accompanied, in both types of bone, by a progressive reduction of glycoproteins and collagen; the diminution of collagen was higher in D- than in N-bone. The presence in D-bone of procollagen fibers with altered mechanical properties might be responsible for an excess of glycoproteins in the newly formed matrix. Calcium salt deposition in this matrix and progressive distension of the fibrous framework are two possible mechanisms by which hypercalcification of D-bone occurs.

Amino Acids↗
PubMedDate not supplied

Aortic collagen biosynthesis during renal hypertension, pregnancy and hypertension during pregnancy in the rat.

The synthesis and deposition of collagen and other proteins has been measured in the aorta of the rat by radiolabeling in short term organ culture. Under these conditions, the synthesis of collagen and other proteins is linear for at least five hours. Autoradiography demonstrates a labeling in all cell layers and protein deposition in the extracellular matrix. Hypertension was induced by renal ischemia using Goldblatt's technique. The synthesis and deposition of collagen was stimulated in aorta from the first week of hypertension and in pregnancy, and was even more increased in hypertensive pregnant animals. Reserpine suppresses the rise in blood pressure in operated animals and prevents these modifications.

Animals↗