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C M Lapière

Publications and source records attributed to C M Lapière.

At least 19 recordsLinked to original sources
PubMed1992

Effect of cell-cell and cell-matrix interactions on the response of fibroblasts to epidermal growth factor in vitro. Expression of collagen type I, collagenase, stromelysin and tissue inhibitor of metalloproteinases.

Investigations of the effect of epidermal growth factor (EGF) on the expression of four genes involved in the turnover of the extracellular matrix, collagen type I, collagenase, stromelysin and tissue inhibitor of metalloproteinases (TIMP) were performed on four strains of skin fibroblasts in vitro. Addition of EGF to subconfluent cultures for increasing periods of time up to 5 days induced an inhibition of procollagen alpha 1(I) mRNA and a strong stimulation of collagenase (100-fold) and stromelysin (1000-fold) mRNAs, whereas the mRNA of TIMP was increased to a lesser extent (5-fold). After a 40 h pulse with EGF, these effects persisted for 24-48 h after withdrawal of the growth factor and slowly diminished thereafter to attain control values after several days. By culturing fibroblasts for increasing periods of time, different levels of confluence were obtained allowing for the deposition of an extracellular biomatrix. The steady-state level of collagenase and stromelysin mRNAs were profoundly depressed in confluent as against non-confluent cultures, whereas no major change for TIMP and procollagen alpha 1(I) mRNAs was observed. Upon treatment of these cultures with EGF for 48h, the steady-state level of collagenase, stromelysin and TIMP increased, whereas procollagen alpha 1(I) mRNA was slightly reduced. These modifications were, at least in part, dependent upon a regulation of the transcription rate, as suggested from run-off experiments. Similar states of confluence were obtained by seeding cells at increasing densities in short-term cultures in which cell-cell contact predominated. In such culture conditions, the collagenase and stromelysin mRNAs were enhanced in high as compared to low density cultures. The response to EGF was progressively decreased for collagenase, stromelysin and, to a lesser extent, TIMP mRNAs at most densities and a complete lack of response to EGF at the highest cell density was observed. Under all culture conditions the modulation of collagenase mRNA was paralleled by similar modifications of enzyme activity. These results emphasize the importance of the cell-cell contacts and cell-matrix interactions in the expression of the genes coding for metalloproteinases or their inhibitor and their modulation by growth factors.

Cell Communication↗
PubMed1992

Evidence for a relationship between Ehlers-Danlos type VII C in humans and bovine dermatosparaxis.

Ehlers-Danlos (ED) syndrome type VII is characterized by the accumulation of collagen precursors in connective tissues. ED VII A and B are caused by mutations in the genes of alpha 1 and alpha 2 collagen I which result in the disruption of the cleavage site of procollagen I N-proteinase. The existence of ED VII C in humans has been hypothesized on the basis of a disorder in cattle and sheep related to the absence of the enzyme. We now present evidence for the existence of this disease in humans, characterized by skin fragility, altered polymers seen as hieroglyphic pictures with electron microscopy, accumulation of p-N-alpha 1 and p-N-alpha 2 collagen type I in the dermis and absence of processing of the p-N-I polypeptides in fibroblast cultures.

Animals↗
PubMed1992

Pretranslational regulation of extracellular matrix macromolecules and collagenase expression in fibroblasts by mechanical forces.

In vivo, the extracellular matrix modulates the phenotype of the connective tissue cells both through its biochemical composition and the transfer of mechanical information. In this study, the mechanical effect was investigated in collagen gels populated by skin fibroblasts maintained under tension (bound lattices (BL)) compared with free retracting lattices (FL) and monolayer on plastic. The overall proteins and collagen synthesis of human skin fibroblasts, investigated by isotopic labeling, were decreased respectively by a factor of about 20 and 40 in FL compared with monolayers and increased by a factor of 4 and 6 in BL versus FL. As assayed by the degradation of [3H]collagen type I by trypsin-activated medium conditioned by fibroblasts under the three models of culture, collagenase activity was inversely regulated and increased in lattices when compared with monolayer culture. It was four times higher in FL than in BL. The steady-state level of mRNA coding for procollagen types I, III, and VI polypeptides, fibronectin, elastin, beta-actin, and procollagenase was determined by cDNA hybridization. The mRNA coding for beta-actin as well as for the various extracellular matrix macromolecules were increased in BL when compared with FL while the level of procollagenase mRNA was lower. These data demonstrate the existence of a modulation of the function of the fibroblasts performed by mechanical forces. This regulation operates, at least in part, at a pretranslational level.

Actins↗
PubMed1992

[The extracellular matrix and its regulation].

The dermis is a differentiated connective tissue whose mechanical properties originate in a network of polymeric macromolecules associated to a variety of glycoproteins and proteoglycans. Each macromolecule contains specific recognition domains allowing their self-association and binding to other macromolecules and to the cell membrane receptors, through. Cell function is regulated by the transfer of information resulting from contact with the polymeric network, as well as by cytokines and growth factors. The structure of the genes encoding the different macromolecules and their regulation sequences are largely known. Various connective tissue disorders are due to alterations of these genes.

Collagen↗
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

Measurement of mechanical forces generated by skin fibroblasts embedded in a three-dimensional collagen gel.

Mechanical activities developed by cells play a significant role in the embryogenesis, development, and physiopathology of pluricellular organisms. A technique is described to measure in vitro the traction force developed by cells seeded into a three-dimensional polymeric collagen lattice. It is based on the use of strain gauges generating an electrical signal upon tension that is amplified and recorded. The intensity of the signal depends on the number and type of cells, cytoskeleton integrity, concentration of collagen in the lattice support, and fetal calf serum in the culture medium. Skin fibroblasts from humans and animals produce traction forces ranging from 100 to 1000 mg per million cells. In the gel under tension, the cells are in mechanical dynamic equilibrium with their support. It is suggested that the mechanical activity of fibroblasts and the control of the tension that they operate on the lattice support participate in the structural organization of the dermis and in its physiologic tension.

Animals↗
PubMed1991

Immunohistochemical expression of epidermal growth factor receptors in nuclei of a subpopulation of keratinocytes and sweat gland cells.

We have raised a polyclonal antibody to the 170-kD epidermal growth factor receptor. We found an intercellular pattern of immunoreactivity in the epidermis as well as a positivity of the cytoplasm of keratinocytes and eccrine secretory cells. In some samples, a nuclear labelling was evidenced in these type of cells. There is a close resemblance in the topographical distribution of these cells with nuclear labelling and those synthesizing DNA under phytohaemagglutinin stimulation.

Cell Membrane↗
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

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

The ageing dermis: the main cause for the appearance of 'old' skin.

Ageing of the skin is associated with progressive atrophy of the dermis, as well as changes in the architectural organization, leading to folds and wrinkles. As the dermis comprises living tissue, dermal changes are not simply the sum of age-related changes occurring in the mesenchymal cells and the supporting macromolecular structures. Chronological ageing reduces the life of fibroblasts in vitro and, to some extent, in vivo; their potential for division being lower in the elderly. Fibroblasts replicate in vitro but only divide very slowly in vivo. Both endogenous factors, e.g. nutritional and endocrine status, and environmental factors, e.g. UV radiation, toxic compounds or free radicals, affect the functions of fibroblasts and the physical and chemical nature of the supporting macromolecules. Mechanical forces also play an important role in the architectural deterioration of the dermis. In vitro models have been developed using dermal cells and supporting tissue to investigate the factors involved in the ageing process.

Animals↗
PubMed1990

Biochemical basis of prolidase deficiency. Polypeptide and RNA phenotypes and the relation to clinical phenotypes.

Cultured skin fibroblasts or lymphoblastoid cells from eight patients with clinical symptoms of prolidase deficiency were analyzed in terms of enzyme activity, presence of material crossreacting with specific antibodies, biosynthesis of the polypeptide, and mRNA corresponding to the enzyme. There are at least two enzymes that hydrolyze imidodipeptides in these cells and these two enzymes could be separated by an immunochemical procedure. The specific assay for prolidase showed that the enzyme activity was virtually absent in six cell strains and was markedly reduced in two (less than 3% of controls). The activities of the labile enzyme that did not immunoprecipitate with the anti-prolidase antibody were decreased in the cells (30-60% of controls). Cell strains with residual activities of prolidase had immunological polypeptides crossreacting with a Mr 56,000, similar to findings in the normal enzyme. The polypeptide biosynthesis in these cells and the controls was similar. Northern blot analyses revealed the presence of mRNA in the polypeptide-positive cells, yet it was absent in the polypeptide-negative cells. The substrate specificities analyzed in the partially purified enzymes from the polypeptide-positive cell strains differed, presumably due to different mutations. Thus, there seems to be a molecular heterogeneity in prolidase deficiency. There was no apparent relation between the clinical symptoms and the biochemical phenotypes, except that mental retardation was present in the polypeptide-negative patients. The activities of the labile enzyme may not be a major factor in modifying the clinical symptoms.

Adolescent↗
PubMed1990

[The various uses of in-vitro reconstituted skin].

Skin is one of the most suitable organ to assess reconstruction in vitro. After forming dermis, by incubation of fibroblasts within a network of collagen fibers, a layer of cultured keratinocytes reconstruct the epidermis. This tissue, even though imperfect, represents a valuable tool for the study of cell physiology, the demonstration of interaction between cell and their support and exchange of information between cells of different types. Within the model, cells acquire a state of differentiation close to that observed in vivo. Reconstructed skin may be used for the study of physiopathology of various cutaneous diseases and allows pharmacotoxicological studies. Keratinocytes in culture, as well as the reconstructed skin, have been successfully used for grafting cutaneous defects.

Cell Communication↗
PubMed1989

The microanatomical basis of facial frown lines.

We studied facial frown lines on cadaver skin. These wrinkles persisting after death were kept unmodified during the collecting procedure; some included the underlying bone. Their microanatomical basis lies in the hypodermis where trabeculae of the retinacula cutis are broader and much shorter underneath the wrinkle than in the surrounding skin. These trabeculae contain striated muscle cells. The hypertrophy of the extracellular matrix of the hypodermal septae is probably related to repetitive mechanical stimuli generated by the muscle cells.

Biopsy↗
PubMed1989

Use of topical ketanserin in the treatment of skin ulcers: a double-blind study.

The use of a 2% ointment formulation of ketanserin, an S2-serotoninergic blocking agent, was investigated in a randomized double-blind clinical trial for its effect on the healing of wounds of patients with decubitus, venous, and ischemic skin ulcers. The result demonstrates a significant difference in favor of the ketanserin-treated group (35 patients) versus the placebo-treated group (37 patients) on the basis of two factors: formation of granulation tissue and epithelialization. In addition, a significant difference of 150% in the initial velocity of wound closure was observed in favor of the patients treated with ketanserin. This effect was persistent during the entire study period.

Administration, Cutaneous↗
PubMed1989

Proteoglycan: collagen interactions in dermatosparactic skin and tendon. An electron histochemical study using cupromeronic blue in a critical electrolyte concentration method.

Proteoglycans (PGs), stained for electron microscopy with Cupromeronic blue, were observed in skin and tendon from normal and dermatosparactic calves. Very frequently they (i.e. dermatan sulphate (DS) PGs) were seen arrayed orthogonally to the collagen fibrils, in the gap zone, usually at the d band, in both diseased and normal tissues. Where UO2(2+) staining showed regular and normal packing of collagen molecules, orthogonally located DS PGs were seen. No qualitative differences between controls and pathological tissues were identified, but quantitatively it appears likely that considerable areas of the surface of dermatosparactic skin collagen fibrils may be without associated PGs.

Animals↗
PubMed1989

Factor XIII of blood coagulation modulates collagen biosynthesis by fibroblasts in vitro.

The effect of activated factor XIII (FXIIIa), the transglutaminase of blood coagulation, on some cellular functions was studied in skin and lung fibroblasts in vitro. FXIIIa repressed the overall protein synthesis and mainly collagen synthesis in a concentration-dependent manner and induced modifications in the proportion of the different types of newly synthesized collagen. The repression of collagen synthesis occurred in cells cultured on plastic (-40%), on coated fibronectin (-53%), on coated collagens (-38%) and within a collagen lattice (-16%). Preincubation of the cells with FXIIIa and labelling in its absence also resulted in such an inhibition. However, when embedded into a fibrin lattice cross-linked by FXIIIa, fibroblasts displayed a higher biosynthetic activity than in untreated fibrin gel. These results suggest that FXIIIa acts through a modulation of the cell-matrix interactions.

Animals↗