摘要:

Expression of four cytokine genes, transforming growth factor (TGF)β2, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and macrophage colony-stimulating factor (CSF-1 also known as M-CSF) was examined to determine whether these genes are developmentally regulated in the brain. Northern blots were performed on RNA isolated from the mouse brain from embryonic day 15 (E15) through postnatal day 9. TGFβ2, gene expression was relatively high in the earliest embryos studied and decreased after E16-E17, and the three transcripts were developmentally regulated. TNF-αand IL-6 were detected in total RNA on all days studied. CSF-1 was detected only in polyadenylated RNA. The data suggest that expression of these cytokines is related to specific developmental events that share cellular functions with regenerative or inflammatory processes.

ISSN:0897-7194    

DOI:10.3109/08977199308991585

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Placenta Growth Factor (PlGF) was recently discovered as a secreted growth factor for vascular endothelial cells and based on its homology to vascular endothelial growth factor (VEGF), can be classified as a new member of this growth factor family. We have carried out polymerase chain amplification (PCR) of RNA from human umbilical vein endothelial cells and placenta tissue and discovered a second species of PlGF, P1GF-2. PlGF-2 has a 21-amino acid insertion not present in PIGF-1 coding for a highly basic region near the C-terminus. This is similar to VEGF189. Northern analysis has shown, that the PlGF gene is expressed only in a limited number of cell types and tissues, e.g. human umbilical vein endothelial cells (HUVE) and placenta. Infection of Sf158 insect cells with recombinant baculoviruses specific for the two forms showed, that both, PlGF-1 and PlGF-2 are secreted efficiently into the supernatant and PlGF-2 can bind with high affinity to heparin. Both PlGF forms had a similar mitogenic potency for bovine aortic endothelial cells. Binding studies with125I-VEGF165demonstrate, that supernatant of PlGF expressing insect cells can compete for receptor binding. Similar to VEGF, PlGF can exist in different forms which are probably generated by differential splicing. The occurrence of two molecular forms of this endothelial specific growth factor suggests different physiological roles of the two forms during placental development and differentiation.

ISSN:0897-7194    

DOI:10.3109/08977199308991586

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Residues 27—31 (Lys-Asp-Pro-Lys-Arg) of the 155-amino acid form of basic fibroblast growth factor (bFGF) are in good agreement with a consensus sequence for nuclear translocation. To evaluate the role of this sequence in mediating the intracellular localization and biological activity of bFGF, basic residues Lys-27, Lys-30, and Arg-31 were changed to neutral glutamine residues by site-directed mutagenesis of the human bFGF cDNA. The bFGF mutant (MIQ-bFGF) was expressed in eukaryotic cells and in prokaryotic cells, from which it was purified to homogeneity. Transient expression of bFGF cDNA and of MIQ-bFGF cDNA in simian COS-1 cells followed by immunolocalization and by subcellular fractionation indicated that both molecules localize in the nucleus, as well as in the cytoplasm of transfected cells, and interact with nuclear chromatin and with eukaryote DNA in a similar manner. Prokaryotic expression of MIQ-bFGF cDNA yields a polypeptide endowed with a receptor-binding capacity and mitogenic activity similar to that exerted by wild-type bFGF. However, recombinant M1Q-bFGF showed a drastically reduced capacity to induce the production of urokinase-type plasminogen activator (uPA) in endothelial cells. The uPA-inducing activity of M1Q-bFGF was fully restored by the presence of soluble heparin in the culture medium. In conclusion, the sequence bFGF(27–31) does not appear to represent a nuclear translocation and/or retention sequence for bFGF. However, neutralization of its basic residues seems to modify the tertiary structure of the growth factor, thus affecting some of its biological properties.

ISSN:0897-7194    

DOI:10.3109/08977199308991587

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Basic fibroblast growth factor is a biologically active peptide with a strong affinity for heparin. This growth factor has been previously shown to be mitogenic for a variety of mesoderm and neuroectoderm-derived cells. The immunohistochemical localization of basic FGF within mouse growing and atretic ovarian follicles is presented in the study. Ovarian tissue samples were obtained either (a) randomly from mice housed in a controlled light environment or (b) following the administration of exogenous gonadotropins to stimulate follicle development. Ovarian samples were fixed in Bouin's fluid for no longer than 18 h. Following fixation and paraffin embedding, sections were exposed to a primary antibody made in rabbits against either (a) human recombinant basic FGF or (b) the 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 or between randomly obtained ovarian samples and those obtained from mice given exogenous gonadotropins. Basic FGF was immunolocalized in follicle basal laminae and was also closely associated with individual follicle cells during all stages of ovarian follicle development. Basic FGF was absent in the theca intema, oocyte cytoplasm, zona pellucida and follicle fluid of normal growing follicles. Individual corpora luteal cells were surrounded by basic FGF but lacked cytoplasmic staining. Atretic follicles exhibited staining patterns similar to their respective stage of follicle development. However, when present, follicle fluid within atretic follicles was strongly positive for basic FGF. These results indicate that basic FGF may be an important factor involved in intraovarian control mechanisms.

ISSN:0897-7194    

DOI:10.3109/08977199308991588

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Multipotent hematopoietic progenitor cell lines (FDCP-Mix) infected with a retroviral vector expressing the GM-CSF gene show functional downregulation of the GM-CSF receptor when maintained in IL-3 and activation of the receptor resulting in synchronous differentiation into mature granulocytes and macrophages on withdrawal of IL-3. This system has now been used to investigate whether or not receptors for some of the other growth factors are also influenced as a consequence of differentiation. We show here the lineage specific receptors for M-CSF, G-CSF and erythropoietin are all upregulated, regardless of whether or not differentiation is induced by GM-CSF or by other conditions. Concomitant induction of the mRNA coding for the ligands M-CSF and G-CSF, but not for erythropoietin, suggests that M-CSF and possibly G-CSF facilitate macrophage or granulocyte differentiation by an autocrine stimulation of the lineage specific receptors. FDCP-Mix mutants that are blocked in their ability to differentiate on exposure to GM-CSF, but that still require GM-CSF for proliferation, do not express increased levels of M-CSF receptor nor M-CSF. Based on these data, we suggest that expression of these lineage specific receptors is part of the intrinsic endogenous program of myeloid differentiation.

ISSN:0897-7194    

DOI:10.3109/08977199308991589

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

One common feature of atherosclerotic plaques is the denudation of the endothelium covering the plaque and subsequent failure of endothelial regrowth in contrast to a marked proliferation of neocapillaries arising from the vasa vasorum within the medial wall. Previous studiesin vitrohave demonstrated the ability of leukemia inhibitory factor (LIF) to potently inhibit aortic endothelial cell growth while only slightly inhibiting the growth of adrenal cortex capillary endothelial cells. This selective effect of LIF on endothelial cells from different sources suggests that it may play a role in the failure of endothelial regrowth in atherosclerosis. Sections of human carotid endartectomy samples were examined byin situhybridization for LIF mRNA expression. In one-third of the samples (4/12) examined, cells within the atherosclerotic plaque exhibited LIF expression. Immunohistochemistry of serial sections suggested that the LIF-positive cells were activated macrophages. These results suggest that LIF may play a role in the pathogenesis of atherosclerosis, particularly the denudation of the large vessel endothelium.

ISSN:0897-7194    

DOI:10.3109/08977199308991590

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

J2E erythroid cells proliferate and differentiate in response to erythropoietin (epo), the red blood cell specific hormone. Using methylcellulose colony assays and suspension cultures we have demonstrated that nearly all the cells stimulated by epo synthesized haemoglobin. To achieve maximum production of haemoglobin J2E cells had to be treated with epo for only 6 h; hormone added subsequently did not enhance haemoglobin synthesis. Although virtually all viable J2E cells produced haemoglobin, the cells matured morphologically at different rates. Thus, upon exposure to epo J2E cells become committed to erythroid terminal differentiation but proceed in an asynchronous manner.

ISSN:0897-7194    

DOI:10.3109/08977199308991591

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Erythropoietin (epo) induced differentiation of the J2E erythroid cell line is characterized by haemoglobin synthesis, together with morphological changes and an immediate increase in proliferation. In this manuscript we have shown that the size of J2E cells decreased during differentiation and the nucleus to cytoplasm ratio was reduced appreciably. Furthermore, major ultrastructural alterations occurred—-mitochondria, rough endoplasmic reticulum and Golgi apparatus decreased in size and number with maturation, while nuclei condensed considerably before extrusion. The use of mitotic indices,3H-thymidine uptakes and flow cytometry confirmed that the immature J2E cells undergo enhanced replication shortly after epo stimulation. In addition, we demonstrated that cell division ceased as the cells entered the final stages of erythroid differentiation. Thus the J2E line provides a useful model, not only for haemoglobin synthesis, but for all aspects of erythroid terminal differentiation.

ISSN:0897-7194    

DOI:10.3109/08977199308991592

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The effects of the PDGF isoforms AA, AB and BB have been studied on the proliferation of normal rat kidney cells, a non-tumorigenic fibroblast cell line which contains both typeaand type p PDGF receptors. On monolayer cells made quiescent by serum deprivation, PDGF-AA is a relatively poor mitogen compared to PDGF-AB and PDGF-BB. When these cells are made density-arrested following continuous incubation with epidermal growth factor, however, they can be restimulated to proliferate by all three PDGF isoforms with similar activity when added at sufficiently high concentration, resulting in phenotypic cellular transformation. Binding of radiolabelled isoforms to confluent NRK monolayers obeys the predictions of an induced receptor dimidiation model, and increases in the order AA

ISSN:0897-7194    

DOI:10.3109/08977199308991593

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor