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PubMed1992

Extracellular matrix constituents and pigment cell expression in primary cell culture.

Three types of pigment cells were isolated and cultured from larval Rana pipiens, and their attachment, maintenance, and proliferation were examined in the presence of extracellular matrix constituents (ECMs) in primary cell culture. The initial profile of pigment cell types present on day 2 of culture reflects the relative attachment of the cells to the dishes. Changes in the numbers of cells present after day 2 reflects the influence of factors present in the culture media on the maintenance, proliferation, or detachment of each type of pigment cell. Fetal bovine serum (FBS) promoted melanophore expression, but inhibited iridophore expression. FBS had no effect on xanthophores. In contrast, ventral skin conditioned medium (VCM), which contains melanization inhibiting factor, strongly stimulated iridophore expression, while it markedly inhibited melanophore expression. VCM had little effect on xanthophores. Of the ECMs tested, collagen type I had no effect on pigment cells. Fibronectin slightly inhibited melanophore expression, while it moderately stimulated iridophores and xanthophores. The stimulatory effect of fibronectin was not as strong as that of FBS or VCM. Laminin was also tested; however, it did not allow pigment cells to attach to the dishes, at least under the culture conditions utilized. The results of these experiments are discussed in terms of the general mechanisms of pigment pattern formation.

Animals↗
PubMed2026

The multilayered cuticle underlying structural coloration in red algae shares features with the metazoan extracellular matrix.

Structural coloration, a physical phenomenon observed in many living organisms, may arise from the interference of light with highly organized surface nanostructures. In some seaweeds, these nanostructures consist of cuticular lamellae in the outer part of the extracellular matrix (ECM) of the epidermis. However, the chemical composition of seaweed cuticles is poorly understood and the molecular components of lamellae remain unidentified. Here, we use integrated genomic, transcriptomic, proteomic, and metabolomic approaches together with analytical profiling of carbohydrates to determine the composition of the multilayered cuticle in the red alga Chondrus crispus and assess its evolutionary conservation. The structural assembly reveals common features with the ECM of animals. The carbohydrate fraction includes a complex mixture of carrageenans and glycosaminoglycan-like compositions. A major von Willebrand factor A domain protein, Lamellae Cohesive Protein, plays a critical role in protein-protein interactions and binding to sulfated polysaccharides. We have further identified the major proteins of the algal cuticle, providing a framework for addressing the evolutionary origins of the cuticle and raising important questions regarding its role, particularly across the red algal life cycle marked by major structural differences in its ECM.

Extracellular Matrix↗
PubMed1992

Binding of Haemophilus ducreyi to extracellular matrix proteins.

A collection of Haemophilus ducreyi isolates were screened for the ability to bind to fibrinogen, fibronectin, collagen, gelatin and laminin by a particle agglutination test using latex beads coated with the individual proteins. Thirteen of 21 isolates reacted with all five extracellular matrix proteins. Binding of organisms to protein-coated latex beads was inhibited by pretreatment of the bacteria with detergent, trypsin or boiling. Two isolates did not bind to collagen and gelatin with one of these not reacting with laminin either. Seven strains which failed to react with laminin did not express pili when examined by electron microscopy. This observation suggests a specific interaction with the pili of H. ducreyi.

Agglutination Tests↗
PubMed1975

Calcification of rachitic rat cartilage in vitro by extracellular matrix vesicles.

Growth plate cartilage from rachitic rats was studied to assess the role in calcification of extracellular matrix vesicles, which are thought to participate in the initial stage of mineralization of connective tissue. The concentration of matrix vesicles and their distribution within the longitudinal septa was found to be normal in rats made rachitic by feeding by a diet low in vitamin D and phosphate for 3 weeks after weaning. Rachitic cartilage matrix did not contain circumvesicular clusters of apatite as does normal cartilage; however, occasional vesicles did enclose one or a few apatite needles. When slices of rachitic cartilage were incubated at 37 C in a metastable calcium phosphate solution ([Ca++] times [PO SEE ARTICLE] equals 3.5 mM identical to 2), apatite formation was initiated in association with matrix vesicles. Under these conditions, mineralization was prominent in the upper hypertrophic cartilage, where matrix vesicles became encrusted with apatite after only 2 to 3 hours of incubation. Vesicular apatite accumulation was inhibited by preheating the cartilage to 60 C for 30 minutes. Measurements of 45Ca uptake by rachitic cartilage slices from metastable calcium phosphates solution also indicated inhibition of calcification by heat. Light microscopic autoradiographs showed 45Ca localization primarily in the matrix of longitudinal septa and substantiated the inhibition site of mineralization in healing rachitic cartilage. The presence of apatite within rachitic vesicles prior to heating and the inhibition of vesicle calcification by heat suggests an active, enzymatically and mediated mechanism of vesicular calcification.

Animals↗
PubMed2026

FOS Regulates Myogenic and Adipogenic Differentiation via Extracellular Matrix Signaling.

In the livestock industry, intramuscular fat deposition is a key factor influencing meat tenderness and flavor. Although FOS (Fos proto-oncogene, AP-1 transcription factor subunit) has been implicated in the regulation of cell proliferation and differentiation, its differential roles in myogenic and adipogenic regulation remain unclear. In this study, we revealed that FOS markedly enhanced myogenic differentiation while inhibiting adipogenic differentiation in muscle stem cells, indicating that it exerts distinct effects on muscle development and intramuscular fat deposition. Mechanistically, FOS modulated extracellular matrix signaling by regulating FAK and PXN phosphorylation, acting as a molecular regulator between the muscle and fat lineages. Furthermore, exon SNPs in FOS were associated with slaughter weight and backfat thickness, and the mutant genotypes weakened its antiadipogenic effect. Collectively, these findings suggest that FOS is an important regulator of myogenic and adipogenic differentiation and is a potential candidate gene for the genetic improvement of meat quality traits.

Animals↗
PubMed1992

Evidence that the loss of rat liver cytochrome P450 in vitro is not solely associated with the use of collagenase, the loss of cell-cell contacts and/or the absence of an extracellular matrix.

Two methods avoiding the widespread technique of collagenase perfusion have been employed to study the regulation of total cytochrome P450 content in rat hepatocyte culture. One technique required the perfusion of the liver with the chelating agent EDTA to dissociate the parenchymal cells prior to culture. Over a period of 48 hr, cultured hepatocytes isolated by EDTA perfusion showed comparable losses of cytochrome P450 as cells isolated by perfusion with collagenase. The second technique involved the culture of 210-240 microns thick "precision cut" liver slices. The results presented here indicate that the liver slices remain viable for 24 hr of culture, but that liver slices also lose their cytochrome P450 content at a comparable rate to collagenase prepared cells in culture. Collectively the results suggest that there is not a direct causal relationship between the loss of cytochrome P450 and one or a combination of the use of collagenase; the loss of cell-cell contacts and the absence of an extracellular matrix.

Animals↗
PubMed1992

[The fibroblast, definition of its phenotype by its "programme" of biosynthesis of the extracellular matrix].

This presentation is an introduction to a symposium focusing on the fibroblast, a virtually ubiquitous cell which is cultured in many laboratories. The traditional definition of the fibroblast based solely on morphological criteria, which has satisfied most biologists for years, now needs reappraisal. The papers delivered at this symposium addressed this issue. Investigations ranged from the phylogenetic origin of fibroblasts in sponges, studied by R. Garrone, to the phenotypic modulations leading to the "myofibroblast" reported by G. Gabbiani, whose manuscript was unfortunately received too late for the conference. The present article describes how the fibroblast can be defined on the basis of its programme for producing extracellular matrix macromolecules. This programme includes a qualitative aspect, i.e., the selection of genes to be expressed: collagen types, variations in alternative splicing patterns of matrix proteins--and a quantitative aspect, i.e., the precise spatial and temporal regulation of production of "selected" macromolecules in order to meet the body's needs. This programme can be studied experimentally, and data are accumulating on the mechanisms involved and on its regulation through intrinsic factors (acting on the genome) and extrinsic and epigenetic factors (vitamins, hormones, nutrition...). Several French laboratories have supplied useful contributions to this research. The results of their investigations, which cover part of this field, are reproduced in this issue of this revue.

Collagen↗
PubMed1992

The alternative-splice isoforms of the PDGF A-chain differ in their ability to associate with the extracellular matrix and to bind heparin in vitro.

Platelet-derived growth factor (PDGF) consists of disulfide-linked homo- or heterodimers of A and B chains. mRNA encoding the A chain (PDGF-A) occurs in two versions that differ by the presence or absence of a single short exon. These alternatively-spliced mRNAs encode polypeptides that differ in length by fifteen amino acids. The longer isoform (PDGF-AL) possesses a highly basic carboxy-terminal extension that is responsible for retaining PDGF-AL homodomers at the cell surface after secretion, while homodimers of the shorter isoform (PDGF-AS) are released into the extracellular medium. We have investigated the mechanism by which PDGF-AL remains in association with the cells that produce it. We expressed epitope-tagged versions of PDGF-AL and PDGF-AS in Cos cells and compared their intra- and extracellular distributions by immunofluorescence microscopy. PDGF-AL, but not PDGF-AS, was detected on and around cells in a diffuse pattern suggesting associated with the extracellular matrix (ECM). Metabolically radiolabelled PDGF-AL, but not PDGF-AS, could be eluted from ECM preparations by washing in high salt. Moreover, PDGF-AL bound reversibly to heparin-Sepharose in vitro at physiological salt concentrations, eluting at a salt concentration around 0.5 M. PDGF-AS did not bind to heparin under the same conditions. Thus, PDGF dimers that contain PDGF-AL may remain immobilized near the cells that secrete them by virtue of binding to heparin-like constituents of the ECM.

3T3 Cells↗
PubMed1992

Extracellular matrix remodelling after coxsackievirus B3-induced murine myocarditis.

Weanling inbred Balb/c mice were intraperitoneally inoculated with a myocarditic variant of coxsackievirus B3. At days 1, 2, 4, 6, 8, 10, 14, 24 and 30 post-infection (p.i.), myocardial tissue was harvested for viral infectivity titrations and histological studies, including routine techniques (haematoxylin-eosin, Masson trichrome and von Kossa) and specialized procedures (silver impregnation for reticulin, picrosirius red stain for collagen and immunoperoxidase labelling for laminin). Virus was isolated as from day 2, reached maximal infectivity at days 6-8 and decreased gradually to become undetectable by day 14. Early histological findings during the 1st week consisted mainly of scattered foci of necrotic myocytes showing calcium deposits; slight mononuclear cell infiltration and fragmentation of both reticulin fibres and pericellular laminin were also present. From the 2nd up to 4th week p.i., inflammatory reaction abated concomitantly with the gradual development of fibrosis, as evidenced by reticulin fibre thickening, irregular laminin distribution and collagen fibre increase. Our results suggest that viral-induced necrosis is able to trigger marked extracellular matrix remodelling even in the case of minimal inflammation.

Animals↗
PubMed1975

Ultrastructural identification of extracellular matrix and cell surface components during limb morphogenesis in man.

Development of the human hand plate (stages 16-17) has been analyzed with emphasis on differentiation of elements within the extracellular matrix and the composition of the mesenchymal cell surface. The epithelial-mesenchymal interface contains a basal lamina and a sublaminar matrix exhibiting: (a) collagen fibrils with characteristic 63-64 nm banding: (b) non-banded filaments, 10-15 nm in diameter; (c) ruthenium red-positive particles, 12-15 nm in diameter; and (d) attenuated threads, 3-5-5-0 nm in diameter which inter-connect particles, fibrils, filaments and the basal lamina. Processes of mesenchymal cells penetrate this matrix network. In addition to staining with ruthenium red, components of basal laminae bind to ferritin-conjugated Concanavalin A, greatest binding being localized on the mesenchymal surface of the lamina. Asymmetry of binding is removed by incubation of exposed laminae with trypsin (5 mug/ml). Regional differences in these staining and binding characteristics within the subepithelial matrix have not been observed in the hand plate. However, precartilaginous extracellular zones deep within the plate are notably unstructured in comparison to the sublaminar region. Ruthenium red-positive materials at mesenchymal cell surfaces display sensitivity to testicular hyaluronidase, Pronase and trypsin but resist removal with neuraminidase and EDTA. These features of the substrate in situ may be important in the regulation of mesenchymal cell behavior during limb morphogenesis in man.

Binding Sites↗
PubMed1979

Extracellular matrix metabolism by chondrocytes. 5. The proteoglycans and glycosaminoglycans synthesized by chondrocytes in high density cultures.

Proteoglycans were extracted from the extracellular matrix of cultures of embryonic chick chondrocytes grown at high density and were purified by CsC1 density gradient centrifugation. The chemical, physical and hyaluronate binding properties of the proteoglycans were similar to those observed in proteoglycans from other hyaline cartilages. Proteoglycans in the media were also purified and on analysis showed three populations of proteoglycans to be present. One population had the physical characteristics of a typical proteoglycan subunit and bound hyaluronate, the other two populations were unable to complex with hyaluronate but one had the physical characteristics of the proteoglycan subunit and the other was of smaller molecular weight. The small molecular weight appears to be a product of the enzymatic degradation of the larger molecular weight species.

Cartilage↗
PubMed1992

Comparison of extracellular matrix antigens in subtypes of bronchioloalveolar carcinoma and conventional pulmonary adenocarcinoma. An immunohistochemical study.

In contrast to the conventional pulmonary adenocarcinomas (CPAs), bronchioloalveolar carcinoma (BAC) grows predominantly by spreading along the existing alveolar septal framework. Within the BAC category, three subtypes have been identified: mucinous, nonmucinous, and sclerosing BAC. Of these, mucinous and sclerosing BACs have worse prognoses compared with nonmucinous BAC. However, the manifestation of aggressive behavior is different between the mucinous and sclerosing types of BACs. Multifocality is often produced by aerogenous spread, especially in the case of mucinous BACs. To study the differences between the BAC subtypes and the conventional pulmonary adenocarcinomas, we employed a battery of immunohistochemical stains marking the extracellular matrix architecture (laminin, collagen IV, fibronectin, and collagen III), a degradative enzyme against a basement membrane component (anti-type IV collagenase) and cellular receptors for laminin and collagen IV (alpha 2 integrin) on 16 BACs (5 mucinous, 5 nonmucinous, and 6 sclerosing) and 30 CPAs. The mucinous and nonmucinous BACs demonstrated neoplastic epithelial cells growing along a continuous basement membrane. A similar growth pattern with intact basement membrane was noted in the periphery of sclerosing BACs. However, in contrast to mucinous and nonmucinous BACs, all cases of sclerosing BACs showed disruption or complete absence of basement membrane components (laminin and collagen IV) around the embedded glands located centrally in the sclerotic fibrous stroma, as was seen in the basement membrane analysis of conventional adenocarcinomas. Furthermore, increased type IV collagenase activity was seen in the small centrally located embedded glands in comparison to the peripheral glands. These architectural alterations of basement membrane disruption and phenotypic expression of degradative activity may be a reflection of the invasive behavior of the sclerosing BACs and their tendency to produce lymph node metastasis. Although the mucinous BACs did not show evidence of basement membrane disruption, there was a marked increase in their levels of type IV collagenase expression along with consistently low levels of alpha 2 integrin receptor (laminin and collagen IV receptor) expression. These findings may be related to the ability of the mucinous BACs to detach from the underlying basement membrane and spread aerogenously, and is to be contrasted with the stromal infiltration and desmoplasia of sclerosing BACs and CPAs.

Adenocarcinoma↗
PubMedDate not supplied

Cell interactions and motility in human lung tumor cell lines HS-24 and SB-3 under the influence of extracellular matrix components and proteinase inhibitors.

The human NSCLC cell lines HS-24 (squamous cell carcinoma) and SB-3 (metastasis derived from an adenocarcinoma) were investigated in respect to cell interactions, motility and invasive properties. HS-24 revealed high self adhesion capacity. Testing the interactions with collagens type I/III or IV, laminin and fibronectin by adhesion, non directional motility and haptotaxis assays, tight interactions and stimulation, particularly with collagen type I/III, was detected. Proteinase inhibitors (E64, Stefin A or leupeptin) revealed a slightly negative influence. Invasion in vitro of lung explants was reduced by leupeptin in a dose dependent manner and slightly increased by plasmin. SB-3 cells revealed low self adhesion. As judged from interaction with fibronectin, these cells have low integrin receptor concentrations and thus reduced adhesiveness to extracellular matrix. Collagen type I/III was inhibitory for undirectional motility and not permissive for haptotaxis. Therefore, it may play a restrictive role during the spread in vivo of these cells. Colonization of lung explants was low and was not influenced by cathepsin B proteinase inhibitors. The results emphasize a particular role of collagens for primary site tumor and metastasis development.

Carcinoma, Non-Small-Cell Lung↗
PubMed1975

Stimulation of corneal differentiation by interaction between cell surface and extracellular matrix. I. Morphometric analysis of transfilter "induction".

The present study was undertaken to determine whether or not physical contact with the substratum is essential for the stimulatory effect of extracellular matrix (ECM) on corneal epithelial collagen synthesis. Previous studies showed that collagenous substrata stimulate isolated epithelia to produce three times as much collagen as they produce on noncollagenous substrate; killed collagenous substrata (e.g., lens capsule) are just as effective as living substrata (e.g., living lens) in promoting the production of new corneal stroma in vitro. In the experiments to be reported here, corneal epithelia were placed on one side of Nucleopore filters of different pore sizes and killed lens capsule on the other, with the expectation that contact of the reacting cells with the lens ECM should be limited by the number and size of the cell processes that can tranverse the pores. Transfilter cultures were grown for 24 h in [3H]proline-containing median and incorporation of isotope into hot trichloroacetic acid-soluble protein was used to measure corneal epithelial collagen production. Epithelial collagen synthesis increases directly as the size of the pores in the interposed filter increases and decreases as the thickness of the filter layer increases. Cell processes within Nucleopore filters were identified with the transmission electron microscope with difficulty; with the scanning electron microscope, however, the processes could easily be seen emerging from the undersurface of even 0.1-mum pore size filters. Morphometric techniques were used to show that cell surface area thus exposed to the underlying ECM is linearly correlated with enhancement of collagen synthesis. Epithelial cell processes did not pass through ultrathin (25-mum thick) 0.45-mum pore size Millipore filters nor did "induction" occur across them. The results are discussed in relation to current theories of embryonic tissue interaction.

Animals↗
PubMed1978

An ultrastructural study of developing extracellular matrix in vitelline blood vessels of the early chick embryo.

This investigation was designed to describe the morphological events in embryonic development of peripheral blood vessels (vasculogenesis) and to relate this process to the appearance of extracellular matrix (ECM) during growth and maturation of these tissues. Extraembryonic vitelline vessels of the early chick embryo were chosen for this study and light, transmission, and scanning electron microscopy were carried out on vessels excised from chick embryos (Hamburger-Hamilton stages 8 through 23). Our data show that early (stage 10) vessels are composed of two distinct epithelial layers, an inner layer of presumptive endothelium surrounded by a layer of splanchnopleuric mesoderm. During development, the inner layer gives rise to mature vascular endothelium while splanchnopleuric mesoderm differentiates to form primitive vascular smooth muscle. Ultrastructural studies show the presence of collagen and basal lamina in the extracellular space between these two layers during initiation of endothelial and smooth muscle cytodifferentiation. Furthermore, ruthenium red-positive material is present on basal surfaces of developing vascular endothelium at this time, indicating possible glycosaminoglycans (GAG) or other polyanionic components of the ECM. These data suggest that the sequential production of basal lamina, collagen (s), and/or GAG's by developing peripheral vessel wall epithelia may be critical to their final differentiation.

Animals↗
PubMed1979

The relationship between extracellular matrix vesicles and calcospherities in primary mineralization of neoplastic bone tissue. TEM and SEM studies on osteosarcoma.

Primary mineralization in neoplastic tissue was studied in osteosarcoma, correlating observations obtained by SEM to those found with TEM. The process is characterized by extracellular matrix vesicles, distributed in the matrix between the forming neoplastic cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatite crystals within the vesicles is followed by accumulation of apatite crystals, disappearance of the vesicular membrane and formation of calcospherites and calcified fronts. The process described here in neoplastic tissue is essentially similar to primary calcification in normal calcified tissues.

Apatites↗