摘要:

AbstractThe human basic Fibroblast Growth Factor (bFGF) gene was shown to encode four polypeptides by an alternative use of initiation codons (three CUG and one AUG). In this report, we present a comparative study of the fate and intracellular localization of individual bFGF isoforms. For this purpose, we have produced the various bFGF isoforms inE. coliand purified them to homogeneity, the 210 amino acid form initiated at CUG1 that contains a nuclear localization sequence (NLS), the 155 amino acid form (AUG-mediated initiation) and the 146 amino acid form (processed form extracted from tissues). While the different bFGFs were taken up by the cell with equal efficiency, more of the 210 amino acid form accumulated in the nucleus and represented 36% of the internalized bFGF compared with 15% in the others. A chimeric protein containing the minimal SV40 Large T NLS (SV40NLS) fused to the 155 amino acid bFGF form (SVbFGF) behaves like the native 155 amino acid form, indicating that nuclear accumulation of exogenous bFGF is not mediated by the NLS-associated function. These results suggest that the amino-terminal part of the 210 amino acid bFGF contains a sequence responsible for its nuclear retention. Bioactivities of the different forms were tested on adult bovine aortic endothelial (ABAE) cells. The bFGF degradation pathways, mitogenic activity and stimulation of rRNA synthesis appeared to be the same for all bFGFs but the stimulation of plasminogen activator was enhanced by the 210 amino acid form and correlated with nuclear accumulation.

ISSN:0897-7194    

DOI:10.3109/08977199409046914

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractMammalian embryo implantation involves a series of complex interactions between maternal and embryonic cells. Uterine polypeptide growth factors may play critical roles in these cell interactions. Basic fibroblast growth factor (basic FGF) is a member of a family of growth factors. This growth factor may be potentially important for the process of embryo implantation because it (a) is stored within the extracellular matrix and is thus easily available during embryo invasion, (b) is a potent modulator of cell proliferation and differentiation and (c) stimulates angiogenesis. The immunolocalization of basic FGF in the uterus during the peri-implantation period of pregnancy is presented in this study. Uterine tissue samples were obtained on days 6–9 of pregnancy with day 1 of pregnancy being the day of a vaginal copulatory plug. Uterine samples were fixed in Bouin's fluid for no longer than 18 h. Following fixation and paraffin embedding, sections were exposed to primary antisera made in rabbits against either (a) human recombinant basic FGF or (b) 1–24 synthetic fragment of bovine basic FGF. The primary antibody was followed by biotinylated goat anti-rabbit IgG and a biotin-avidin-peroxidase complex. There were no differences in the immunolocalization of basic FGF using either source of primary antibody. Our results demonstrated both temporal and spatial changes in the localization of immunoreactive basic FGF within the implantation chamber during days 6–9 of pregnancy. Inter-implantation sites resembled the non-pregnant uterus with basic FGF present in extracellular matrices including basal laminae. On day 6 of pregnancy, decidual cells within the primary decidual zone lacked both intracellular and pericellular basic FGF while non-decidualized uterine stroma resembled inter-implantation sites. By days 7–8 of pregnancy, the secondary decidual zone had formed and was characterized by the distinct pericellular localization of basic FGF around individual decidual cells. By day 9 of pregnancy, the mesometrial region was forming and contained cords of decidual cells and a labyrinth of maternal blood vessels. The decidual cells contained diffuse intracellular basic FGF. Trophoblast cells were devoid of basic FGF at all times examined. These results indicate that basic FGF is present within the implantation chamber on days 6–9 of pregnancy and may be involved in the decidual cell response, trophoblast cell invasion and angiogenesis.

ISSN:0897-7194    

DOI:10.3109/08977199409046915

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractVascular endothelial growth factor (VEGF) is an angiogenic growth factor which binds to two structually related tyrosine kinase receptors denoted KDR and FLT1. To compare the interaction of VEGF with each receptor, cell lines which express individual receptor subtypes were identified using Northern blot hybridization. Bovine aortic endothelial (ABAE) cells and WM35 melanoma cells were found to express KDR, while FLT1 was primarily expressed on SK-MEL-37. Both receptor subtypes were detected on another melanoma cell line (WM9). Heparin augmented VEGF binding to KDR-expressing cells (ABAE and WM35), but inhibited VEGF binding to FLT 1-expressing cells (SK-MEL-37 and WM9). The concentration of heparin required for half maximal stimulation of VEGF binding to KDR-expressing cells (500 ng/ml) was 25 times greater than that required for half maximal inhibition of binding to FLT1-expressing cells (20 ng/ml). In WM9 cells, the effect of heparin was bimodal; low concentration inhibited, while higher concentrations stimulated binding of125I-VEGF. Placenta growth factor (PlGF-1) is a recently described growth factor structurally similar to VEGF. PlGF-1 had a negligible or no effect on125I-VEGF binding to KDR-expressing cells (ABAE, WM35), but did compete for binding to FLT1 expressing cells (SK-MEL-37 and WM9). Addition of heparin had no effect on its ability to compete for binding with125I-VEGF. The data indicate differential regulation of the two VEGF receptors by heparin and extended specificity of FLT1 receptor, but not KDR, for binding PlGF-1 growth factor.

ISSN:0897-7194    

DOI:10.3109/08977199409046916

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractA 24 hr TGF-β1 treatment (4 ng/ml) of SV40-transformed WI38 embryonic fibroblasts (VA13 cells) causes a moderate but reproducible inhibition of their serum-stimulated growth. By immunoprecipitation with the PAb122 antibody, we show that serum stimulation of previously serum-deprived cells causes a dephosphorylation of the wild type P53 protein, which is accentuated by the TGF-%β1 treatment. The TGF-β1-enhanced dephosphorylation effect is also observed in two other cell lines growth-inhibited by TGF-β1, but which do not contain Large T (mink lung CCL64 and human KHOS cells). On the contrary, TGF-β1 treatment of the untransformed WI38 fibroblasts stimulates their growth, without affecting the phosphorylation of P53. Such treatment did not affect the expression of the corresponding mRNA nor the level of synthesis of the protein. The results suggest that the P53 protein could be a downstream target of TGF-β1 action on those cells growth-inhibited by the factor.

ISSN:0897-7194    

DOI:10.3109/08977199409046917

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractCollagen metabolism is a balance between synthesis and lysis. Both are under tight regulatory control. TGF-βreverse the impairment of healing seen after glucocorticoid treatmentin vivoBoth TGF-βand glucocorticoids are known to regulate collagen metabolism directly. We have examined the effect of dexamethasone and of TGF-βindividually and in combination on the regulation of procollagen type 1, interstitial collagenase and tissue inhibitor of metallo-proteinase-1 (TIMP-1) synthesis at both the protein and mRNA levels in low passage human dermal fibroblasts. Dexamethasone treatment decreased synthesis of procollagen and caused a dose dependent down-regulation of TIMP-1 synthesis. Interstitial collagenase synthesis by fibroblasts was detectable but low. Thus, glucocorticoid treatment of fibroblasts tilts the balance of collagen metabolism away from accumulation. TGF-βhad opposing effects, stimulating both procollagen and TIMP-1 synthesis at the protein and mRNA levels. TGF-βwas able to cause a dose-dependent reversal of the glucocorticoid induced decrease in procollagen and TIMP-1 synthesis. Stimulation of healing in glucocorticoid treated animals by TGF-βmay be by the direct action of this agent upon fibroblast collagen metabolism.

ISSN:0897-7194    

DOI:10.3109/08977199409046918

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractWe have characterized the expression and processing of Osteogenic Protein-1 (hOP-1), a bone morphogenic protein of the TGF-βfamily, in Chinese hamster ovary cells. The hOP-1 is initially synthesized as a monomeric 50 kDa pro-protein that is dimerized, glycosylated, and then proteolytically cleaved at the Arg-Xaa-Xaa-Arg maturation site in an acidic cellular compartment before secretion into the medium. Of the four potential N-linked glycosylation sites two are used, one in the mature domain and one in the pro-domain. Gel permeation chromatography of secreted hOP-1 in physiological buffers yields an apparent molecular weight of 110-120 k, indicating that after proteolytic processing the two pro-domains remain non-covalently associated with the disulfide linked mature dimer in a complex termed soluble hOP-1. Purified soluble hOP-1 is significantly more soluble in physiological buffers than the purified mature OP-1.

ISSN:0897-7194    

DOI:10.3109/08977199409046919

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractWe recently showed that osteogenic protein-l(OP-l), a bone morphogenetic protein member of TGF-βsuperfamily, induces endochondral bone formationin vivo, and stimulates growth and differentiation of osteoblasts in rat calvarial-derived cell cultures. In the present study, we examined the effect of OP-1 on cell growth and expression of markers that are characteristic of osteoblast phenotype using the clonal rat osteosarcoma cells (ROS 17/2.8). A comparison of OP-1 and TGF-β1 effects on cell growth showed that, both OP-1 and TGF-β1 inhibited DNA synthesis up to 90 percent and 60 percent of the controls at concentrations of 10 ng/ml and 1 ng/ml, respectively, in serum-free medium. In the presence of 5% serum, TGF-β1 did not have any significant inhibitory effects while 40 ng OP-1/ml inhibited the DNA synthesis up to 80% of the controls. Examination of collagen synthesis showed that 40 ng OP-1/ml increased the expression of type I collagen mRNA, and thus increased collagen synthesis (4-fold), as examined by collagenase-digestible protein. Evaluation of markers that are characteristic of the osteoblast phenotype demonstrated that OP-1 stimulated cAMP production in response to PTH (10-fold at 200 ng/ml), alkaline phosphatase specific activity (ALPase) (4-fold at 80 ng/ml), and osteocalcin (OC) synthesis (4.5-fold at 40 ng/ml). Northern blot analysis revealed that OP-1 increased mRNA expression for both ALPase and OC in a dose-dependent manner. These data collectively demonstrate that OP-1 suppresses cell proliferation and stimulates the expression of markers characteristic of osteoblast phenotype in rat clonal osteoblastic osteosarcoma cells (ROS 17/2.8).

ISSN:0897-7194    

DOI:10.3109/08977199409046920

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor