Presence Of Extracellular Matrix Proteins Research Articles

Association of endometriosis in horses with differentiation of periglandular myofibroblasts and changes of extracellular matrix proteins

Periglandular fibrosis and cystic dilation of uterine glands are associated with equine endometriosis. The presence of extracellular matrix proteins (collagen type I, III and IV, laminin and fibronectin) in healthy and endometriotic specimens was demonstrated by immunohistochemistry. The distribution of collagen I, but not collagen III, was dependent on the stage of the oestrous cycle. The arrangement of collagen I and collagen III in endometriotic specimens was similar to that in normal endometrium. In periglandular fibrosis, collagen IV, laminin and fibronectin deposition outside the basement membrane was observed. In these regions, stromal cells were characterized immunohistochemically as myofibroblasts because of their expression of a-smooth muscle actin, and occasionally tropomyosin and desmin. Periglandular differentiation of contractile cells could be interpreted as a reaction to support the extrusion of secretions in cystic dilated glands. Moreover, the changes of extracellular matrix proteins are characteristic for neoplastic lesions, although further development of endometriosis to benign or malignant tumours is not known in horses. Knowledge of the factors responsible for these fibroblastic modulations may be the key to explaining the pathogenesis of endometriosis.

Extracellular-matrix gene expression during mouse submandibular gland development

Early morphogenesis of mouse submandibular glands begins on late day 11 of fetal development when the epithelium begins to bud from the surrounding mandibular mesenchyme. Using total RNA collected from fetal BALB/c submandibular glands, steady-state levels of mRNA expression for extracellular matrix molecules were measured using quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR). By comparing the PCR amplification products of both the cellular mRNA and a synthetic template, pMATRIX, it was possible to measure the direct expression of collagens α2(I), α1(111), αl(IV), fibronectin, laminin B2, elastin and lysyl oxidase genes. There was an observed trend for an increasing concentration of collagen α2(I), collagen al(III) and lysyl oxidase mRNA molecules per cell on day 16 of development. The relative abundance of elastin mRNA was detectable only on day 16. Fibronectin and laminin B2 were more constitutively present but had their highest copy number per cell on day 16. The presence of extracellular-matrix protein was confirmed by immunohislochemistry using day-16 fetal glands and adult glands. With the construction of the pMATRIX supertemplate and the advent of quantitative, competitive RT-PCR technology, it has been possible to measure small changes in the steady-state concentrations for extracellular-matrix mRNA during salivary gland development.

Immunohistochemical evaluation of TGF-beta and extracellular matrix proteins expression in rat squamous cell carcinomas.

The aim of this study was to establish a possible association between the degree of differentiation of squamous cell carcinomas (SCC) derived from rat oral tissues treated in vivo with carcinogen 4NQO, and the expression of TGF-beta on epithelial cells and the distribution of extracellular matrix proteins (laminin-collagen type IV). A parent tumor showing a spectrum of differentiation was used to establish clonal subpopulations that formed differentiated SCC and undifferentiated (spindle cell phenotype) tumours following transplantation to athymic mice. Immunohistological findings revealed the absence of TGF-beta staining on epithelial cells and extracellular matrix proteins in spindle cell tumours. In contrast, staining of SCC revealed a significant number of TGF-beta positive cells and the presence of extracellular matrix proteins. The findings suggested that there is a positive correlation between histological differentiation, TGF-beta expression and the elaboration of extracellular matrix proteins.

Actions of Molecules which Regulate Hemopoiesis on Endothelial Cells: Memoirs of Common Ancestors?

The proliferation and differentiation of hematopoietic stem cells (hematopoiesis) takes place in close contact with stromal cells and matrix in bone marrow. Hematopoiesis requires cytokines, collectively termed colony stimulating factors (CSFs), which act on progenitor cell populations and induce their commitment to a specific lineage. For instance, leukemia, inhibitor factor and stem cell factor act on pluripotent cells and immature progenitors, granulocyte-macrophage colony stimulating factor (GM-CSF) acts at early stages of the development of myelomonocytic lineage, whereas granulocyte-colony stimulating factor (G-CSF) and macrophage-colony stimulating factor (M-CSF) act on more mature cells of the same lineage and are only required later during the differentiation of this cell lineage. A second important element for the hematopoietic process is the presence of extracellular matrix proteins, which bind CSFs and correctly present the molecules to specific receptors present on the surface of the progenitor cells. Finally, stromal cells (i.e. fibroblasts, endothelial cells and adipocytes) which support the growth of hematopoietic stem cells in vitro, are crucial for the production of CSFs and protein matrix and regulate the passage of mature cells from bone marrow to bloodstream. Idiopathic myelofibrosis is an example of the relevance of microenvironment in hematopoiesis. This disease is characterized by fibroblast and basement membrane accumulation, appearance of myofibroblasts and modification of the capillary network and provokes a bone marrow aplasia. In this article we review recent studies on the role of hemopoietic cytokines on stromal cells, in particular on endothelial cells, and propose a double role for CSFs in hematopoiesis: to induce the commitment of progenitor cells and to maintain the behavior of bone marrow endothelial cells.

Integrins and extracellular matrix-proteins in the different components of the Wilms' tumour.

The Wilms' tumour (WT) is composed of blastema, epithelium and mesenchyme; the epithelium and possibly also the mesenchyme develop from the blastema, parallel to embryonal development. Since interactions between cell adhesion receptors and extracellular matrix (ECM) proteins play an important role in tissue maturation, we examined the expression of the integrin subunits alpha 1-alpha 6, beta 1 and beta 4, and of the ECM proteins fibronectin, laminin and collagen I and IV, in 20 frozen WT samples and in 5 fetal and 2 adult kidneys. The integrin and ECM protein distribution in tumour epithelium and mesenchyme showed strong similarities to that in their fetal counterparts, whereas the tumour blastema differed strongly from the fetal blastema. In the WT blastema different components were recognized. Undifferentiated blastema, characterized by expression of alpha 3 and alpha 6 and the virtual absence of ECM proteins. Blastema with epithelial commitment, showing increased expression of alpha 3 and alpha 6 and the appearance of alpha 2 and, as a very early phenomenon, production of laminin. Blastema with mesenchymal commitment, with loss of alpha 3 and alpha 6 and expression of alpha 1, alpha 4 and alpha 5 and presence of ECM proteins. It is speculated that the inability of the (undifferentiated) blastema to produce ECM proteins is related to its relatively high metastatic potential when compared with epithelium and mesenchyme.

Effect of manganese on tyrosylprotein sulfotransferase activity in PC12 cells

Recent studies in our laboratory have revealed that Mn 2+ is capable of promoting cell spreading and neurite outgrowth in PC12 cells, a process which is dependent on Mn 2+ stimulation of the interaction between extracellular matrix (ECM) components and their corresponding integrin receptors. Since the major ECM proteins implicated in the Mn 2+-induced morphogenesis, fibronectin and vitronectin, are both tyrosine sulfated, it was of interest to determine whether Mn 2+ can regulate the activity of the enzyme responsible for tyrosine sulfation, tyrosylprotein sulfotransferase (TPST). Results of the present studies demonstrated that Mn 2+ can suppress TPST activity in PC12 cells in both a time and concentration-dependent manner at concentrations of Mn 2+ (0.1 to 1 mM) that promote morphological changes in PC12 cells. Since uptake of Mn 2+ may occur via the Ca 2+ channel, LaCl 3, an inhibitor of Ca 2+ transport, was examined and found not to prevent the suppression of TPST activity induced by Mn 2+, suggesting that Mn 2+ may function at an extracellular site. Suppression of TPST activity occurred with cells plated in serum-free medium on a substrata consisting of either serum or polylysine, suggesting that attachment to extracellular matrix was not an absolute requirement for regulation of activity. Consistent with this is the fact that an RGD-containing pentapeptide did not prevent suppression of TPST activity. Results from the present study demonstrated that Mn 2+ is capable of promoting the suppression of TPST activity in PC12 cells at concentrations that have been shown to induce cell spreading and neurite outgrowth. However, unlike the Mn 2+-induced morphological changes, the presence of ECM proteins is not an absolute requirement for suppression of TPST activity.

Freezing adhesion molecules in a state of high-avidity binding blocks eosinophil migration.

Leukocyte extravasation is mediated by multiple interactions of adhesive surface structures with ligands on endothelial cells and matrix components. The functional role of beta 1 (CD29) integrins (or very late antigen [VLA] proteins) in eosinophil migration across polycarbonate filters was examined under several in vitro conditions. Eosinophil migration induced by the chemoattractant C5a or platelet-activating factor was fully inhibited by monoclonal antibody (mAb) 8A2, a recently characterized "activating" CD29 mAb. However, inhibition by mAb 8A2 was observed only under filter conditions that best reflected the in vivo situation, i.e., when the eosinophils migrated over filters preincubated with the extracellular matrix (ECM) protein fibronectin (FN), or when the filters were covered with confluent monolayers of cultured human umbilical vein endothelial cells (HUVEC). When bare untreated filters were used, mAb 8A2 had no effect, whereas the C5a-directed movement was prevented by CD18 mAb. Studies with alpha-subunit (CD49)-specific mAbs indicated that the integrins VLA-4 and -5 mediated migration across FN-preincubated filters, and VLA-2, -4, -5, and -6 were involved in eosinophil migration through filters covered with HUVEC. In contrast with the activating CD29 mAb 8A2, a combination of blocking CD49 mAbs or the nonactivating but blocking CD29 mAb AIIB2 failed to inhibit completely eosinophil migration over FN-preincubated or HUVEC-covered filters. mAb 8A2 stimulated binding to FN but not to HUVEC. Moreover, eosinophil migration over FN-preincubated or HUVEC-covered filters was significantly inhibited by anti-connecting segment 1 (CS-1) mAbs, as well as the soluble CS-1 peptide (unlike migration across bare untreated filters). Thus, inhibition of eosinophil migration by mAb 8A2 depended upon the presence of ECM proteins and not upon the presence of HUVEC per se. In conclusion, "freezing" adhesion receptors of the beta 1 integrin family into their high-avidity binding state by the activating CD29 mAb 8A2 results in a complete inhibition of eosinophil migration under physiological conditions. Hence, activation of beta 1 integrin-mediated cell adhesion may represent a new approach to prevent influx of inflammatory cells.

Induction of a putative laminin-binding protein of Streptococcus gordonii in human infective endocarditis.

There is evidence to suggest that the virulence of Streptococcus strains in infective endocarditis might be due to the expression of binding sites for the extracellular matrix proteins of damaged valves. In this communication, we draw attention to one laminin-binding protein from a strain of Streptococcus gordonii isolated from a patient with human endocarditis. This 145-kDa protein was found on the cell wall of the bacterium. The level of expression of this binding protein might be regulated by the presence of extracellular matrix proteins: the protein was lacking after in vitro selection of laminin, collagen I, and fibronectin nonbinding variants, and it was recovered after growth of the variants when laminin or collagen I was added to the growth medium. It was also missing after 10 subcultures in minimal medium, indicating some positive control. Furthermore, the 145-kDa protein was recognized as a major antigen by sera from patients treated for streptococcal infective endocarditis, while sera from patients with valvulopathies gave only slight recognition, suggesting an increase of the expression of this protein during infective endocarditis. It was also shown that the 145-kDa protein carried a collagen I-like determinant detected with anti-human collagen I antibodies.

Immunohistochemical Studies of Peters' Anomaly

Peters' anomaly is a congenital abnormality that affects mainly the posterior cornea. The pathogenesis is unclear. By immunohistochemical methods, the authors determined the presence of extracellular matrix proteins, including fibronectin, laminin, and collagen types I, III, IV, V, and VI, in seven corneal buttons from five patients with Peters' anomaly. Type III collagen was the only protein absent in either the pathologic or normal human corneas. Compared with normal controls, the stromal lamellae in Peters' anomaly corneas were more irregular and more closely packed. In addition, the fibronectin staining was markedly enhanced in all seven Peters' anomaly corneas. Staining with collagen type VI was also mildly increased. These results suggest that extracellular matrix elements such as fibronectin may be important factors in this developmental disorder.