摘要:

AbstractMacrophage Inflammatory Protein-1α(MIP-1α) can inhibit the proliferation of multipotent haemopoietic cells. Using the FDCP-Mix A4 multipotent stem cell line, MIP-1αwas shown to inhibit IL-3 stimulated cell cycling (assessed using the [3H]-thymidine“suicide”assay). Furthermore MIP-1αcan inhibit IL-3-stimulated [3H]-thymidine incorporation in FDCP-Mix cells, with half maximal inhibition observed at 3 ng/ml MIP-1α. Prostaglandin E2, but not MlP-1αwas able to elevate cyclic AMP levels in FDCP-Mix A4 cells although both agents can cause growth inhibition. However, MIP-1αaddition resulted in a pertussis-toxin-insensitive increase in the level of the second messenger inositol 1,4,5 trisphosphate (Ins 1,4,5P3). This response was both rapid (maximal at 5 seconds) and transient. A half maximal effect was observed at 5 ng/ml MIP-1αand the dose dependency correlated with that for MIP-1αmediated growth inhibition. A rapid increase in cytosolic Ca2+levels was also observed in response to MIP-1α. Inositol lipid hydrolysis and an increase in cytosolic Ca2+(signals normally associated with proliferation) may therefore be implicated in growth inhibitory mechanisms in multipotent cells.

ISSN:0897-7194    

DOI:10.3109/08977199509036876

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThe establishment of IL-3-dependent multipotent progenitor cell lines from Hox-2.4-expressing bone marrow cells suggests that homeobox genes may contribute to immortalization of early myeloid cells. A survey of 20 independently derived multipotent IL-3-dependent cell lines established from either src-virus-infected long-term bone marrow cultures (FDCP-mix) or Multi-CSF-virus (M3MuV)-infected bone marrow revealed that Hox-2.4 was not expressed in any of these cell lines. In addition DNA rearrangements were not observed. We conclude that activation of Hox-2.4 is not an obligatory event in the immortalization of early myeloid cells.

ISSN:0897-7194    

DOI:10.3109/08977199509036877

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractFibroblast growth factor 9 (FGF-9), a novel member of the FGF family, was found to have thrombopoietic activityin vitroandin vivo.In anin vitromegakaryocyte colony-stimulating factor assay, anti-mouse interleukin-6 (IL-6) monoclonal antibody neutralized FGF-9 activity. This suggests that the activity may be exerted via IL-6 induction. BALB/c mice that received subcutaneous FGF-9 injections of 4 to 100μg/day for 2 weeks showed a dose-dependent transient increase in peripheral platelet counts 10 to 12 days after the first treatment. Histologic studies showed a marked increase in megakaryocytes in the bone marrow and extramedullary hematopoiesis in the spleen and the liver. Examination of changes in the DNA content of bone marrow megakaryocytes revealed that the ploidy distribution underwent a marked shift 3 days after FGF-9 injection, with a large increase in the 2N megakaryocyte population. The major modal ploidy shifted from the normal 16N to 2N. The number of megakaryocyte progenitor cells in FGF-9-treated mice increased up to 1.5-fold in the bone marrow and 10-fold in the spleen on day 6. These results indicate that FGF-9 acts on thein vivoproliferation of megakaryocytes.

ISSN:0897-7194    

DOI:10.3109/08977199509036878

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractPlatelet-derived growth factor-BB (PDGF-BB) triggered signal transduction was investigated in human foreskin fibroblasts with endogenous PDGFβ-receptors, and porcine aortic endothelial (PAE) cells with stably transfected PDGFβ-receptors. Immunoprecipitation and immunoblotting showed that PDGF induced dose-dependent autophosphorylation of PDGFβ-receptor, and that PLC-γassociates with autophosphorylated PDGFβ-receptors and becomes phosphorylated. Activation of PLC-γis known to induce fluctuations of the concentration of cytoplasmic calcium ([Ca2+]i). Microfluorometry and digital imaging were employed for measurements of the concentration of [Ca2+]i. In both cell types the growth factor induced four types of [Ca2+]iresponses; no rise, a small and sluggish monophasic rise, a biphasic rise with an initial transient peak followed by a sustained elevation, and finally regular oscillations. The frequencies and amplitudes of the oscillatory responses were independent of agonist concentration after stimulation with PDGF-BB. Latency, the period from application of stimulus to the first [Ca2+]ipeak, was reduced at higher concentrations of agonist. Also, the proportion of responding cells increased with higher concentrations of ligand. Oscillations of [Ca2+]iwere elicited at submaximal concentrations of agonist. In PAE cells PDGF-BB triggered a single [Ca2+]ipeak in absence of external Ca2+. Ligand-induced oscillations and sustained increases of [Ca2*]iwere counteracted by the inorganic Ca2+channel blocker Ce3+. These results show that similar types of [Ca2+]iresponses occur in different cell types independently of whether the PDGFβ-receptors are expressed endogeneously or after transfection. Potentially, the different [Ca2+]iresponses have distinct physiological consequences.

ISSN:0897-7194    

DOI:10.3109/08977199509036879

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractBradykinin may act as a promoter of endometrial regeneration. Bradykinin-like immunoreactivity was detected immunocytochemically in the glandular epithelium and stroma of human endometrium. The staining was localized around the stroma and especially in the cells undergoing mitosis. Relatively weak staining was seen in the stromal cells of secretory endometrium, which was predominantly localised around the basal vacuoles of endometrial glands. During the late secretory phase, the intensity of staining was diminished throughout the endometrium: the glandular epithelium showed weak staining and stroma appeared negative. As phosphatidate, the product of phospholipase D pathway, may mediate cell proliferation, the effect of 17β-oestradiol on bradykinin-evoked phospholipase D activity assayed as accumulation of [3H]phosphatidylbutanol ([3H]PtdBut) was examined in [3H]myristic acid-labelled primary cultures of human endometrial stromal cells. Bradykinin induced a rapid accumulation of [3H]PtdBut in a time-dependent manner, indicating phospholipase D activation. Pretreatment of stromal cells with 17β-oestradiol enhanced the bradykinin-evoked phospholipase D activity. These results suggest that bradykinin-like immunoreactivity is strongly associated with proliferative stromal cells undergoing mitosis, a process that may be mediated by phospholipase D activation as the magnitude of this enzyme's activationin vitroappears to be regulated by 17β-oestradiol.

ISSN:0897-7194    

DOI:10.3109/08977199509036880

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThe principal objective of this communication has been to determine the manner in which two tissue culture substrata (plastic dishes and type I collagen gels) modulate the response of adult skin fibroblasts to TGF-β1 with respect to hyaluronan (HA) synthesis. Our results indicate that (a) fibroblasts cultured on collagen gels synthesised more HA compared to cells plated at the same density on plastic dishes, (b) this up-regulation in total HA synthesis by collagen-cultured cells was accompanied by an increase in the relative proportion of high molecular mass species of newly synthesised HA, and (c) the specific effect of TGF-β1 on HA synthesis was dependent upon the substratum: i.e. TGF-β1 inhibited HA synthesis by subconfluent fibroblasts cultured on both substrata, had no apparent effect on confluent cells cultured on collagen gels, and stimulated HA synthesis by confluent cells cultured on plastic dishes. The TGFβ-stimulation of HA synthesis by confluent fibroblasts cultured on plastic dishes persisted when these cells were transferred to collagen gels in the absence of further TGF-β1; interestingly, a second exposure of these plastic pre-incubated cells to TGF-β1 whilst growing on collagen resulted in a down-regulation in HA synthesis. Confluent fibroblasts pre-incubated with TGF-β1 for 24 h on plastic dishes (i.e. under conditions which stimulate HA synthesis) also displayed an HA-dependent stimulation in cell migration when subsequently plated onto collagen gels in the absence of further cytokine.

ISSN:0897-7194    

DOI:10.3109/08977199509036881

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractFibroblast growth factors (FGF) are multifunctional, heparin binding polypeptides that share structural similarity, but differ in their target cell specificity and expression pattern. Here we describe the cloning and expression of the mouse homologue of FGF9, and the use of a panel of soluble FGF receptors and genetically engineered cells to study its receptor binding specificity. FGF9 is found to bind with high affinity (kd: 0.25 nM) to FGFR3, for which a specific ligand has not yet been identified. FGF9 can also bind, albeit with a lower affinity, to FGFR2 but does not bind FGFR1 or FGFR4. There is no significant binding to either FGFR3 or FGFR2, expressed either as soluble receptors or in heparan sulfate deficient cells, in the absence of heparin. Moreover, receptor binding of FGF9 requires heparin in a manner specific to the receptor type. In conclusion FGF9 presents a unique case of ligand-receptor specificity and fulfills the criteria as a high affinity, heparin-dependent ligand for FGFR3.

ISSN:0897-7194    

DOI:10.3109/08977199509036882

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractVascular endothelial growth factor (VEGF) is an angiogenic protein which acts on both endothelial and trophoblast cells. In first trimester placenta, VEGF immunoreactive protein was detected in cytotrophoblast shell suggesting a role in the regulation of cytotrophoblast growth and differentiation as they also expressed VEGF receptor (flt-1) protein. VEGF and flt-1 immunoreactive proteins were expressed in Hofbauer cells within the villous mesenchyme, macrophages and in maternal decidual cells while weak VEGF immunoreactive protein was seen in syncytiotrophoblast surrounding the placental villi in first and second trimester placentae. At term, there was relatively weak VEGF and flt-1 immunostaining in the syncytiotrophoblast while intense VEGF immunostaining was seen in the Hofbauer and maternal decidual cells. Extravillous trophoblast showed immunostaining for flt-1 but no staining for VEGF. Both amnion and chorion expressed strong VEGF immunoreactivity throughout gestation. Smooth muscle cells surrounding the vein and arteries of the umbilical cord showed weak VEGF immunoreactivity while no immunoreactivity was localised in endothelial cells. VEGF stimulated parathyroid hormone-related protein (PTHrP) release (mean (±SD): basal, 0.96±0.03; 10 ng/ml VEGF165, 2.07±0.18 and 20 ng/ml VEGF165, 2.43±0.18 pmol/l/well of PTHrP1–86) in condition medium from immortalised first trimester trophoblast cell line. These results suggest that VEGF in addition to acting as an autocrine mitogen for trophoblast proliferation may also function as a paracrine mediator of vascular tone by releasing vasorelaxants from trophoblasts.

ISSN:0897-7194    

DOI:10.3109/08977199509036883

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor