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At least 199 records · Page 11Linked to original sources
PubMed2002

FSH and TGF-beta superfamily members regulate granulosa cell connective tissue growth factor gene expression in vitro and in vivo.

Connective tissue growth factor (CTGF) is a heparin-binding growth factor implicated in diverse epithelial cell types as a paracrine regulator of mitosis, angiogenesis, cellular taxis, and remodeling of the extracellular matrix. To understand the possible roles of CTGF in the ovarian paracrine system, we studied CTGF gene expression by granulosa cells in relation to their stage of cellular differentiation using both in vitro and in vivo methodologies. Untreated monolayer granulosa cell cultures from immature rats abundantly expressed the approximately 2.5-kb CTGF mRNA transcript (determined by Northern analysis), but had low levels of aromatase activity (an index of granulosa cell differentiation). Treatment for 48 h with FSH (0.1-10 ng/ml) dose-dependently inhibited (>or=50%) CTGF mRNA expression, but enhanced aromatase enzyme activity. This in vitro observation of CTGF mRNA down-regulation coinciding with FSH-induced granulosa cell maturation is substantiated by studies of in vivo ovarian CTGF expression in FSHbeta knockout mice. Northern blot and in situ hybridization analyses demonstrate high levels of CTGF expression in the granulosa cells of preantral follicles blocked from further development by the absence of FSH. The action of FSH (10 ng/ml) was mimicked in vitro by 8-bromo-cAMP (1.0 mM) and was augmented by the additional presence of androgen (1 micro M 5alpha-dihydrotestosterone), consistent with mediation by intracellular cAMP. Conversely, treatment of granulosa cell cultures with TGFbeta1 (0.1-10 ng/ml) dose-dependently increased CTGF mRNA levels up to 12-fold at a dose of 10 ng/ml, without affecting aromatase activity. Cotreatment with FSH (0.1-10 ng/ml) dose-dependently suppressed the stimulatory action of TGFbeta1 (10 ng/ml) on CTGF mRNA, but substantially enhanced aromatase activity beyond levels induced by FSH alone. Importantly, other TGFbeta superfamily members known to be produced in the ovary (growth/differentiation factor-9 and activin A; 10 ng/ml) stimulated granulosa cell CTGF mRNA in a similar fashion as TGFbeta1 (10 ng/ml), and this was also inhibited by FSH (10 ng/ml). These data show that granulosa cell CTGF gene expression is inversely related to the stage of granulosa cell differentiation, being directly inhibited by FSH via cAMP-mediated signaling. CTGF mRNA abundance in nondifferentiated granulosa cells is up-regulated in vitro by TGFbeta1, growth/differentiation factor-9, and activin, suggesting paracrine roles for these growth/differentiation factors in the regulation of CTGF synthesis in mammalian ovaries.

Activins↗
PubMed2002

GM-CSF increases airway smooth muscle cell connective tissue expression by inducing TGF-beta receptors.

Fibrosis around the smooth muscle of asthmatic airway walls leads to irreversible airway obstruction. Bronchial epithelial cells release granulocyte/macrophage colony-stimulating factor (GM-CSF) in asthmatics and are in close proximity to airway smooth muscle cells (ASMC). The findings in this study demonstrate that GM-CSF induces confluent, prolonged, serum-deprived cultures of ASMC to increase expression of collagen I and fibronectin. GM-CSF also induced ASMC to increase the expression of transforming growth factor (TGF)-beta receptors type I, II, and III (TbetaR-I, TbetaR-II, TbetaR-III), but had no detectable effect on the release of TGF-beta1 by the same ASMC. The presence of GM-CSF also induced the association of TGF-beta1 with TbetaR-III, which enhances binding of TGF-beta1 to TbetaR-II. The induction of TbetaRs was parallel to the increased induction of phosphorylated Smad2 (pSmad2) and connective tissue growth factor (CTGF), indicative of TGF-beta-mediated connective tissue synthesis. Dexamethasone decreased GM-CSF-induced TbetaR-I, TbetaR-II, TbetaR-III, pSmad2, CTGF, collagen I, and fibronectin. In conclusion, GM-CSF increases the responsiveness of ASMC to TGF-beta1-mediated connective tissue expression by induction of TbetaRs, which is inhibited by corticosteroids.

Animals↗
PubMed1984

A factor synthesized by rabbit periosteal fibroblasts stimulates bone resorption and collagenase production by connective tissue cells in vitro.

Unstimulated monolayer cultures of confluent rabbit periosteal fibroblasts synthesize a factor that stimulates bone resorption in vitro. Furthermore it stimulates rabbit chondrocytes and mouse osteoblasts to synthesize collagenase. The factor has no effect on dead bone in culture, and its activity on live bone is mediated principally by osteoclasts, since it is 75% inhibited by salmon calcitonin. Characterization of the factor by gel filtration and isoelectric focusing indicates an Mr in the range 15000-25000 and a pI corresponding to approx. pH 4.7. These biological and physiochemical properties are similar to those reported for a factor released by peripheral blood monocytes. However, whereas human monocyte factor in both the crude and partially-purified state exhibits interleukin-1 activity, crude and fractionated periosteal fibroblast-conditioned medium does not. This is the first report of a conditioned medium containing a molecule like the monocyte-factor which appears to have no interleukin 1 activity. The factor may be synthesized by a wide range of cell types, and could have an important role in mediating connective tissue degradation during both physiological and pathological resorption.

Animals↗
PubMed1981

[Reaction of sera from rabbits immunized with synthetic poly-L-alanine with myocardial interstitial connective tissue cells].

Sera from rabbits immunized with synthetic poly-L-alanine (PL-ala) in complete Freund's adjuvant (CFA) have been examined by the indirect immunofluorescence (IF) technique. Half of the sera reacted with fibroblasts of the interstitial connective tissue of the myocardium. The reactions were obtained with all sections of the myocardium of man and other mammals except rabbits. The sera obtained before or after immunization with synthetic poly-L-lysine fibroblasts were obtained with preparations of IgG or F(ab')2 fragments of IgG isolated from sera of animals immunized synthetic polypeptides can be applied to study by the IF technique of the antigenic structure of tissues including lymphoid and tumor tissues.

Animals↗
PubMed1980

Extracellular matrix metabolism by chondrocytes. 7. Evidence that L-glutamine is an essential amino acid for chondrocytes and other connective tissue cells.

The incorporation of [3H]glycine into acid-insoluble protein and of [3H]acetate into glycosaminoglycans by cultured chick chondrocytes was stimulated by the addition of L-glutamine to the incubation medium. The effect of exogenous L-glutamine on protein synthesis was studied further by examining changes in the sedimentation patterns on sucrose gradients of ribosomes isolated from chondrocytes incubated in presence and absence of L-glutamine. It was found that the absence of L-glutamine caused a disaggregation of polyribosomes that was revered by the addition of this amino acid to the culture medium. No detectable glutamine synthetase activity could be measured in avian articular cartilage. These results indicate that L-glutamine is an essential amino acid for cartilage in that an extracellular supply of this amino acid is required for the maintenance of protein and glycosaminoglycan synthesis. A dependence of L-glutamine was also demonstrated for other avain connective tissues.

Amino Acids, Essential↗
PubMed1992

Proteoglycans synthesized by the hepatic granulomas isolated from schistosome-infected mice and by the granuloma-derived connective tissue cell lines.

Proteoglycans synthesized in vitro by periovular granulomas isolated from livers of schistosome-infected mice were compared with those produced by granuloma-derived cell lines: the primary cell line GR and the permanent cell line GRX. Proteoglycans were metabolically labelled with 35S-sulfate and extracted with 4 M guanidine-HCl containing 2.0% Triton X-100, in the presence of proteinase inhibitors. The radiolabelled proteoglycans were purified and characterized by anion-exchange, gel-filtration and affinity-column chromatography. Heparan sulfate proteoglycans (HS-PGs) and chondroitin sulfate/dermatan sulfate-containing proteoglycans (CS/DS-PGs) were detected in both the culture medium and the cell-associated fractions obtained from GR cells. More than 90% of the cell-associated HS-PG from these cells contained a hydrophobic portion, as evidenced by their ability to bind to octyl-Sepharose. In contrast, among the secreted proteoglycans, it was the CS/DS-PG and not the HS-PG that bound to this resin. The major fractions of cell-associated and secreted proteoglycans from GRX cells were HS-PGs. Similar to HS-PGs from GR cells, 50% of the cell-associated HS-PG bound to octyl-Sepharose, while only 20% of secreted proteoglycans (HS-PGs) bound to this resin. The proteoglycans purified from the whole granuloma were composed mainly of DS-PG, of a size and hydrophobicity similar to the CS/DS-PG from GR cells. Possible correlations among the structure, secretion, distribution and function of proteoglycans in granulomatous reactions are discussed.

Animals↗
PubMed2001

[Detection of progesterone receptors in connective tissue cells of the lower nasal turbinates in women].

BACKGROUND: The syndrome of the Rhinopathia gravidarum has been frequently discussed in the literature, but the etiology is yet unknown. An increase of oestrogen and progesterone concentration is said to contribute to the pathogenesis. The aim of this study was to localize estrogen (ER) and progesterone receptors (PgR) in the nasal mucosa of women and to compare the localization with the distribution of mast cells (MC). The patients' medical history was obtained with special emphasis on nasal symptoms during pregnancy, the menstrual cycle, or with the use of oral contraceptives. METHODS: Immunohistochemistry (IHC) was performed on formalin-fixed paraffin sections (nasal mucosa, inferior turbinate of 40 women) with monoclonal antibodies against ER, PgR, and mast cell tryptase. RESULTS: PgR-positive cells were found in fibroblasts (nuclear staining). The cytoplasmic staining for ER in serous glands and excretory ducts and for PgR in the interstitium of glands is considered nonspecific. The pattern of the receptor distribution was different from the pattern seen in the MC-IHC. No significant statistical results were obtained comparing the patient's medical histories and the immunohistochemical findings. CONCLUSIONS: Our findings possibly indicate a direct influence of progesterone on fibroblasts and therefore on the consistency of the extracellular matrix. Additionally, estrogen and progesterone might cause rhinopathic symptoms indirectly by changing the concentration of neurotransmitters (e.g. substance P, NO) and their receptors.

Adult↗
PubMed1978

[Contractile connective tissue cells and wound healing. Function of myoid fibroblasts in reparative regeneration of mesenchymal tissue].

The present survey deals with processes of wound healing with special regard to fibroblast proliferation. Comparative experimental studies on reparative and regenerative fibroblastic proliferates and findings from the literature point to the importance of a fibroblast modification with myoid structure in certain phases of the reparative regeneration of the connective tissues. The ultrastructural picture of the myoid fibroblasts and their functional significance are discussed with regard to wound healing in man.

Achilles Tendon↗
PubMed1983

Relationship between connective tissue cells and fibronectin in a sequential model of experimental hepatic fibrosis.

The cellular and non-cellular components of fibrous septa formed at early and late stages in a sequential model of experimental hepatic fibrosis have been investigated using ultrastructural and immunocytochemical techniques. In the early septa, cells with intermediate features between lobular Ito cells and active fibroblasts were formed. These cells frequently displayed subplasmalemmal microfilaments (myofibroblast-like cells). Macrophages were also present. Scanty typical fibroblasts were present in the late septa. This cellular recruitment might be related to an extracellular glycoprotein-fibronectin-which is at present under investigation as a chemotactic factor for fibroblasts. Strong positivity for fibronectin in early septa and its sharp decrease in late septa seems to support this view. Fibroblasts and/or macrophages are the likely source of fibronectin synthesis.

Animals↗
PubMed1995

In vitro clonal analysis of cardiac outflow tract mesenchyme.

In vitro clonal analyses were performed to gain insight into the mechanisms that control development of neural crest-derived cardiac outflow tract mesenchyme of quail embryos. The cardiac neural crest originates from the posterior rhombencephalic neural tube. The cells leave the neural tube and migrate through the posterior visceral arches to the outflow tract of the heart, where they form the conotruncal ridges. Mesenchyme cells derived from the neural tube from somitic levels 1-3 contained 5 types of clone-forming cells. One class of clones contained up to 6 phenotypes; smooth muscle cells, connective tissue cells, chondrocytes, sensory neuron precursors, serotonergic (putative enteric) neurons, and pigment cells. Another type of clone was totally pigmented, containing melanocytes only, whereas a third type consisted entirely of smooth muscle cells. The remaining classes of clones contained 3 and 4 phenotypes, respectively. Subsequently, mesenchymal cells obtained from posterior visceral arches were cloned in vitro. The major observations from these experiments are the following. 1) The cells have lost the capacity to form sensory neurons. 2) The capacity to form pigment cells is lost as well. 3) Four types of morphologically distinguishable clones were found. The frequency of one type of clone that contains ectomesenchymal cells only (smooth muscle cells, connective tissue cells, and chondrocytes) increased from zero at Hamburger and Hamilton stage 19+/20 to 67% at stage 24, possibly giving rise to visceral arch-derived structures. The frequency of the other 3 types of clones decreased with progressing embryonic development, indicating that these clone-forming cells either pass through the visceral arches, and/or are being converted to cells with fewer developmental potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Phospholipid modifications during conversion of hepatic myofibroblasts into lipocytes (Ito-cells).

Connective tissue cells of liver parenchyma (perisinusoidal myofibroblasts) can be induced to express the lipocyte (Ito cell) phenotype. We have studied phospholipid synthesis and phosphate incorporation during this in vitro conversion, induced by insulin and/or indomethacin, in the established murine cell line GRX. Phospholipid synthesis, measured by [14C]acetate incorporation, was increased after a full induction of the lipocyte phenotype. The 32Pi incorporation into phospholipids was increased from the beginning of induction. Phosphatidic acid and phosphatidylinositol synthesis were increased early in the induction, whilst the increase of major constitutive phospholipids was significant only after the full lipocyte phenotype induction. The presence of unsaturated fatty acids in phospholipids was increased in lipocytes. Linoleic acid was present only in diacylglycerols and in phosphatidylinositol. Since we have shown previously that linoleic acid was not present in triacylglycerols, this result indicates the importance of future studies on activation of phosphatidylinositol cycles in induction of lipocyte phenotype in liver connective tissue cells.

Acetates↗