Biomedical subjects

G Vairo

Publications and source records attributed to G Vairo.

At least 37 records · Page 2Linked to original sources

PubMed1992

Suppression of growth factor-induced CYL1 cyclin gene expression by antiproliferative agents.

A recently identified novel mammalian cyclin (CYL1), induced by growth factors and apparently functional during the G1 phase of the cell cycle, is of potential significance, given that cell division is primarily controlled in G1. We have measured CYL1 gene expression in murine bone marrow-derived macrophages (BMM), a normal cell type dependent upon colony-stimulating factors (CSFs) for survival and proliferation. The induction of CYL1 mRNA levels correlated strongly with stimulation of DNA synthesis, since elevated CYL1 mRNA levels occurred in response to the mitogenic stimuli, CSF-1, and granulocyte/macrophage CSF, but not to nonmitogenic macrophage-activating agents. BMM are subject to cell cycle arrest by numerous agents, including tumor necrosis factor alpha, interferon gamma, bacterial lipopolysaccharide, and agents that increase cAMP. These antiproliferative agents suppressed CSF-1-stimulated CYL1 gene expression, even when added late in G1. This pattern of CYL1 gene expression was remarkably consistent with the ability of these agents to inhibit progression into S phase. The mechanisms of negative growth regulation are largely unknown, and given the likely importance of G1 cyclins in the control of cell division, we propose that antiproliferative agents may exert their effects by suppressing G1 cyclin gene expression.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1992

Biochemical events accompanying macrophage activation and the inhibition of colony-stimulating factor-1-induced macrophage proliferation by tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide.

Agents that can arrest cellular proliferation are now providing insights into mechanisms of growth factor action and how this action may be controlled. It is shown here that the macrophage activating agents tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN gamma), and lipopolysaccharide (LPS) can maximally inhibit colony stimulating factor-1 (CSF-1)-induced, murine bone marrow-derived macrophage (BMM) DNA synthesis even when added 8-12 h after the growth factor, a period coinciding with the G1/S-phase border of the BMM cell cycle. This inhibition was independent of autocrine PGE2 production or increased cAMP levels. In order to compare the mode of action of these agents, their effects on a number of other BMM responses in the absence or presence of CSF-1 were examined. All three agents stimulated BMM protein synthesis; TNF alpha and LPS, but not IFN gamma, stimulated BMM Na+/H+ exchange and Na+,K(+)-ATPase activities, as well as c-fos mRNA levels. IFN gamma did not inhibit the CSF-1-induced Na+,K(+)-ATPase activity. TNF alpha and LPS inhibited both CSF-1-stimulated urokinase-type plasminogen activator (u-PA) mRNA levels and u-PA activity in BMM, whereas IFN gamma lowered only the u-PA activity. In contrast, LPS and IFN gamma, but not TNF alpha, inhibited CSF-1-induced BMM c-myc mRNA levels, the lack of effect of TNF alpha dissociating the inhibition of DNA synthesis and decreased c-myc mRNA expression for this cytokine. These results indicate that certain biochemical responses are common to both growth factors and inhibitors of BMM DNA synthesis and that TNF alpha, IFN gamma, and LPS, even though they all have a common action in suppressing DNA synthesis, activate multiple signaling pathways in BMM, only some of which overlap or converge.

Animals↗

PubMed1992

Regulation of pinocytosis in murine macrophages by colony-stimulating factors and other agents.

Lucifer yellow (LY) accumulation was used to measure macrophage pinocytosis. The hematopoietic growth factors, macrophage colony-stimulating factor (CSF-1), granulocyte-macrophage CSF (GM-CSF), and interleukin 3, and the macrophage activators, lipopolysaccharide and zymosan, all stimulated LY uptake in both murine bone marrow-derived macrophages (BMMs) and resident peritoneal macrophages (RPMs) without affecting LY efflux. The stimulation of pinocytosis in the poorly cycling RPMs and in BMMs by nonmitogens dissociates stimulation of pinocytosis from subsequent DNA synthesis. Regulation of pinocytosis in BMMs appears to be independent of that of urokinase-type plasminogen activator expression. The increases in CSF-mediated BMM pinocytosis were not inhibited by pertussis toxin, by elevations in intracellular cAMP, or by glucocorticoids and were only partially inhibited by inhibitors of Na+/H+ antiport and Na+/K(+)-ATPase activities. Protein kinase C activation could be involved in regulating BMM pinocytosis because phorbol myristate acetate, oleoylacyglycerol, and exogenously added phospholipase C can all stimulate it. Ca2+ ionophores were inactive, whereas the Na+/H+ ionophore monensin potently inhibited BMM pinocytosis.

Animals↗

PubMed1992

Coumarins: macrophage proteinase production and pinocytosis.

Coumarins, which are thought to stimulate macrophage proteinase activity, have been advocated for the treatment of high protein oedemas, such as obstructive lymphoedema. In experiments with cultured murine macrophages, coumarin and 7-hydroxycoumarin (10(-3) or 10(-4) M) had no significant effect on plasminogen-activator activity, plasminogen-independent fibrinolytic activity or pinocytosis. Although no in vitro effect on macrophage proteinase activity was found, it is possible that coumarins activate other cell types in vivo and thus effectively treat lymphoedema.

Animals↗

PubMed1991

Inhibition of colony-stimulating factor-stimulated macrophage proliferation by tumor necrosis factor-alpha, IFN-gamma, and lipopolysaccharide is not due to a general loss of responsiveness to growth factor.

The role of stimulatory factors, such as the CSF, in the regulation of hemopoiesis has been extensively documented. Less is known of the negative regulators of hemopoiesis. In this report, we show that the macrophage activating agents, TNF-alpha, IFN-gamma, and LPS, are all potent inhibitors of CSF-1-stimulated murine bone marrow-derived macrophage (BMM) DNA synthesis and increase in cell numbers. The inhibitory effects of TNF-alpha and IFN-gamma do not appear to be due to endotoxin contamination in the recombinant cytokine preparations. The inhibition of proliferation is reversible and is not due to a general loss of growth factor responsiveness, inasmuch as the three agents do not inhibit CSF-1-stimulated BMM survival, protein synthesis, or fluid phase pinocytosis. Because TNF-alpha and LPS are known to rapidly and potently down-modulate CSF-1 receptor levels in BMM, the results also suggest that low levels of receptor occupancy are sufficient for biological responses to CSF-1. The inhibitory effects of TNF-alpha, IFN-gamma, or LPS were also seen when granulocyte-macrophage-CSF or IL-3 was used to stimulate BMM DNA synthesis. The results suggest that TNF-alpha, IFN-gamma, and LPS appear to be inhibiting CSF-stimulated proliferation by acting at a post-receptor level, possibly by regulation of some critical event(s) in the mitogenic signaling pathway.

Animals↗

PubMed1991

Activation and proliferation signals in murine macrophages. Biochemical signals controlling the regulation of macrophage urokinase-type plasminogen activator activity by colony-stimulating factors and other agents.

Purified hematopoietic growth factors such as colony-stimulating factor-1 (CSF-1) or macrophage CSF, granulocyte-macrophage CSF, and interleukin-3 or multi-CSF, stimulate the urokinase-type plasminogen activator (u-PA) activity of murine bone marrow-derived macrophages (BMM) and resident peritoneal macrophages. Granulocyte-CSF was inactive. The increases in BMM u-PA activity were inhibited by the glucocorticoid dexamethasone, and by agents that raise intracellular cyclic adenosine monophosphate levels, including prostaglandin E2 and cholera toxin. These changes in u-PA activity were paralleled by corresponding changes in u-PA mRNA levels. Evidence was obtained for protein kinase C and phospholipase C-mediated stimulation of BMM u-PA activity and mRNA levels; however, no evidence was found for an involvement of Na+/H+ exchange or Na+, K(+)-ATPase activity, Ca2+ fluxes, or pertussis toxin-sensitive G proteins. Several findings point to a dissociation between macrophage u-PA expression and DNA synthesis.

Animals↗

PubMed1991

Signalling through CSF receptors.

The finely regulated process of blood cell formation is under the control of a family of glycoprotein hormones, known as colony-stimulating factors (CSFs), and their receptors. The complexity of the intracellular mechanisms involved in the action of such factors has been appreciated only recently. In this review, Gino Vairo and John Hamilton discuss the biochemistry of CSF action and its relevance to growth control, and examine the possibility that different CSFs may use common control pathways within the one cell type.

Animals↗

PubMed1990

Na+/H+ exchange involvement in colony-stimulating factor-1-stimulated macrophage proliferation. Evidence for a requirement during late G1 of the cell cycle but not for early growth factor responses.

Na+/H+ exchange activation by growth factors is proposed to be an important early signal for mitogenesis; however, little is known of its duration and requirement during later stages of the cell cycle. Macrophage-specific colony factor (CSF-1) rapidly activates murine bone marrow-derived macrophage Na+/H+ exchange, resulting in stimulation of Na+,K(+)-ATPase activity. The response to CSF-1 is maintained for at least 24 h. Inhibition of Na+/H+ exchange with 5-N,N-dimethylamiloride prevents CSF-1-stimulated DNA synthesis and cell growth. This is unlikely to be due to cytoplasmic acidosis, but more likely reflects a requirement for Na+/H+ exchange-mediated Na+ influx. DMA addition even up to 8 h after the growth factors suppresses S-phase progression. Na+/H+ exchange appears not to be involved in the induction of other early growth factor responses (c-fos and c-myc mRNA induction and general RNA and protein synthesis). We propose that growth factor-stimulated Na+/H+ exchange late in G1 of the cell cycle is required for S-phase progression but not for certain early growth factor responses.

Amiloride↗

PubMed1990

Inhibition of the signaling pathways for macrophage proliferation by cyclic AMP. Lack of effect on early responses to colony stimulating factor-1.

Colony stimulating factor-1 (CSF-1) stimulates DNA synthesis in quiescent murine bone marrow-derived macrophages (BMM). CSF-1 action has been shown to involve activation of the CSF-1 receptor kinase. The protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (PMA), is itself weakly mitogenic and synergises with CSF-1 for stimulation of BMM DNA synthesis suggesting a possible role for protein kinase C in the stimulation of BMM DNA synthesis. In this report we show that several agents which raise intracellular cAMP (8-bromoadenosine 3':5'-cyclic monophosphate, 3-isobutyl-1-methylxanthine, cholera toxin, and prostaglandin E2) reversibly inhibit DNA synthesis in BMM induced by CSF-1, granulocyte macrophage-colony stimulating factor, interleukin-3, and PMA. The suppressive action of cAMP elevation on the proliferative response to CSF-1 can be manifested even late in the G1 phase of the cell cycle. Several CSF-1-stimulated earlier responses, viz. protein synthesis, Na+/H+ exchange, Na+,K(+)-ATPase and c-myc-mRNA expression, were not inhibited thus showing a striking difference from some other cellular systems involving growth factor-mediated responses. c-fos-mRNA levels were raised and stabilized by the cAMP-elevating agents, and this modulation was not altered by CSF-1. Thus, the signaling pathways in the macrophages involving tyrosine kinase and protein kinase C activation are associated with increased proliferation while those involving elevation of cAMP (and presumably activation of cAMP-dependent protein kinases) appear to have an inhibitory effect.

1-Methyl-3-isobutylxanthine↗

PubMed1989

Activation and proliferation signals in murine macrophages: relationships among c-fos and c-myc expression, phosphoinositide hydrolysis, superoxide formation, and DNA synthesis.

Murine bone marrow-derived macrophages (BMM) undergo DNA synthesis in response to growth factors such as colony stimulating factor-1 (CSF-1) and granulocyte-macrophage CSF (GM-CSF). These macrophages can also be "activated," but without subsequent DNA synthesis, by a number of other agents, including lipopolysaccharide (LPS), concanavalin A, zymosan, formyl-methionyl-leucyl-phenylalanine (FMLP), and the Ca2+ ionophore, A23187. When BMM are treated with a range of stimuli, there is some, although not perfect, correlation between transient elevations in both c-myc mRNA and c-fos mRNA levels and increases in DNA synthesis. However, enhanced DNA synthesis and oncogene expression are readily dissociated from rises in inositol phosphates and, by implication, phospholipase C-mediated hydrolysis of phosphatidyl inositol 4,5-bisphosphate. Superoxide formation in BMM can also be dissociated from the other responses and does not necessarily depend on protein kinase C activation.

Animals↗

PubMed1988

Activation and proliferation signals in murine macrophages: stimulation of Na+,K+-ATPase activity by hemopoietic growth factors and other agents.

Purified colony stimulating factor (CSF-1) stimulates the Na+,K+-ATPase activity of murine bone marrow-derived macrophages (BMM) and resident peritoneal macrophages (RPM) measured as ouabain-sensitive 86Rb+ uptake. Similar concentrations of CSF-1 stimulate the Na+,K+-ATPase activity and DNA synthesis in BMM whilst ouabain, a specific inhibitor of the Na+,K+-ATPase, also inhibits this CSF-1-mediated DNA synthesis. Other purified hemopoietic growth factors, granulocyte-macrophage CSF (GM-CSF) and interleukin-3 (IL-3), and the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), even though differing in their mitogenic capabilities, are also stimulators of the Na+,K+-ATPase activity in BMM and RPM. The non-mitogenic agents, lipopolysaccharide (LPS) and Concanavalin A (Con A), are also active. CSF-1 stimulation of the Na+,K+-ATPase was shown to be dependent on elevation of intracellular Na+ via an amiloride sensitive Na+-channel, most likely representing Na+/H+ exchange activity. Such stimulation of Na+,K+-ATPase activity via activation of the Na+/H+ exchange appears to be a necessary but insufficient early macrophage response for subsequent DNA synthesis.

Animals↗

PubMed1988

Activation and proliferation signals in murine macrophages: stimulation of glucose uptake by hemopoietic growth factors and other agents.

Purified colony-stimulating factor (CSF-1) (or macrophage colony stimulating factor [M-CSF]) stimulated the glucose uptake of murine bone marrow-derived macrophages (BMM) and resident peritoneal macrophages (RPM) as measured by 3H-2-deoxyglucose (2-DOG) uptake. Similar concentrations of CSF-1 stimulated the 2-DOG uptake and DNA synthesis in BMM. Other purified hemopoietic growth factors, granulocyte-macrophage CSF (GM-CSF) and interleukin-3 (IL-3) (or multi-CSF), and the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), even though differing in their mitogenic capabilities on BMM, were also stimulators of 2-DOG uptake in BMM and RPM. The nonmitogenic agents, lipopolysaccharide (LPS) and concanavalin A (Con A), were also active. The inhibition by cytochalasin B and by high concentrations of D-glucose suggest that the basal and stimulated 2-DOG uptake occurred via a carrier-facilitated D-glucose transport system. The responses of the two macrophage populations to the hemopoietic growth factors and to the other agents were quite similar, suggesting that events that are important for the induction of DNA synthesis are not tightly coupled to the earlier rise in glucose uptake. For the BMM, the ability of a particular agent to stimulate glucose uptake did not parallel its ability to promote cell survival. However, stimulation of glucose uptake could still be a necessary but insufficient early macrophage response for cell survival and subsequent DNA synthesis.

Animals↗

PubMed1988

Activation and proliferation signals in murine macrophages: synergistic interactions between the hematopoietic growth factors and with phorbol ester for DNA synthesis.

There has been recent interest in the synergistic interactions between the growth factors involved in the in vitro control of hematopoiesis and other cell lineages. As a convenient model system, such interactions governing the DNA synthesis in murine bone marrow-derived macrophages (BMMs) were studied. By themselves, murine colony-stimulating factor-1 (CSF-1) and recombinant murine granulocyte-macrophage CSF (GM-CSF) were stimulators of DNA synthesis in quiescent or noncycling BMMs, whereas recombinant murine interleukin-3 (IL-3) and the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), were weak mitogens. On the other hand, murine granulocyte CSF (G-CSF), concanavalin A (Con A), and lipopolysaccharide (LPS) were inactive on their own. When the quiescent BMMs were exposed to combinations of the CSFs, there were striking synergistic effects for both GM-CSF and IL-3 with suboptimal doses of CSF-1, with a smaller effect for GM-CSF with IL-3 and little or no effect for CSF-1 with G-CSF. CSF-1, GM-CSF, and IL-3 could also synergize with TPA; CSF-1 cooperated with 1-oleoyl-2-acetylglycerol (OAG), both sets of results pointing to an interaction with protein kinase C. LPS completely abolished the CSF-1-mediated stimulation of DNA synthesis. We propose that BMMs are suitable normal cells in which to examine in depth the various mechanistic possibilities for these interactions.

Animals↗

PubMed1986

CSF-1 stimulates glucose uptake in murine bone marrow-derived macrophages.

3H-2-deoxyglucose was used as an isotopic tracer for the measurement of glucose uptake into quiescent murine bone marrow derived macrophages. A purified colony stimulating factor (CSF-1) was shown to stimulate 3H-2-deoxyglucose uptake in a dose-dependent manner. This stimulation was rapid, with a maximal effect seen at 20-30 minutes after growth factor addition. Both the inhibition by cytochalasin B and also the relative degree of competition by high concentrations of a series of glucose analogues suggest that the basal and CSF-1 stimulated 2-deoxyglucose uptake occur via a carrier facilitated D-glucose transport system. The data indicate that a purified growth factor can increase the glucose uptake in macrophages, a finding which could be relevant to the survival and/or the proliferative response of this and other haemopoietic cell types.

Animals↗

PubMed1985

Purification of two forms of colony-stimulating factor from mouse L-cell-conditioned medium.

A modified procedure for the purification of the colony-stimulating factors (CSFs) in mouse L-cell-conditioned medium is used to isolate two forms of CSF, which are separable by reversed-phase high performance liquid chromatography with 300-A pore size supports. The specific biological activity of these CSFs (2 X 10(9) colonies/mg) was considerably higher than has been achieved by other methods. Even at high concentration (200 pM) both molecules stimulated predominantly more macrophage than granulocyte colonies; however, the less hydrophobic form appeared to stimulate the formation of more pure granulocytic colonies. Almost twice as much of the less hydrophobic CSF was recovered from L-cell-conditioned medium. Analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that both forms of L-cell CSF had apparent molecular masses of approximately 70,000 daltons. However, on reduction with 2-mercaptoethanol, while both forms generated a 39,000-dalton subunit, the less hydrophobic form also yielded a 32,000-dalton subunit. Storage of either form of L-cell CSF at pH 2.1, in the presence of acetonitrile or isopropanol, destroyed the biological activity. Electrophoretic analysis of the L-cell CSFs stored under these conditions indicated that this was associated with a spontaneous dissociation of the CSF dimer into the inactive subunits. There was some charge heterogeneity (pI 3.5-4.7) indicating different degrees of glycosylation. The unique N-terminal amino acid sequences of both forms of CSF were the same: (Lys-Glu-Val-Ser-Glu-His-X-Ser-His-Met-Ile-Gly-Asn). Thus, the polypeptide chains appear to be identical for the subunits of both forms of L-cell CSF.

Amino Acids↗

PubMed1985

CSF-1 stimulates Na+K+-ATPase mediated 86Rb+ uptake in mouse bone marrow-derived macrophages.

86Rb+ was used as an isotopic tracer for the measurement of K+-uptake into quiescent murine bone marrow-derived macrophages. 86Rb+ uptake was inhibited by ouabain indicating a Na+K+-ATPase is being measured. In support of this finding, increased sensitivity to ouabain inhibition was seen when the K+ content of the medium was reduced. A purified colony stimulating factor (CSF-1) was shown to stimulate the ouabain-sensitive 86Rb+ uptake in a dose-dependent manner. Such colony stimulating factor stimulation of 86Rb+ (K+) influx was rapid, with a maximal effect seen 10 minutes after growth factor addition followed by a gradual decrease. Thus increased Na+K+-ATPase activity was an early response of macrophages to the colony stimulating factor.

Animals↗

PubMed1985

2-Substituted-3-pyridinolethers as hypolipidemic and platelet aggregation inhibiting agents.

Some 2-substituted 3-pyridinolethers were synthesized, with one side chain bearing a carboxylic function; among these there are products having structure analogies with the prostaglandins. The results of hypolipidemic and hypocholesterolemic tests on experimental hyperdyslipidemic animals, as well as those on the inhibition of platelets aggregation and on fibrinolytic activity are reported.

Animals↗

PubMed1985

Stimulation of bone marrow-derived and peritoneal macrophages by a T lymphocyte-derived hemopoietic growth factor, persisting cell-stimulating factor.

Several lines of evidence indicated that P cell-stimulating factor (PSF), a T lymphocyte-derived lymphokine known to stimulate the growth of hemopoietic stem and progenitor cells, also acted on macrophages. PSF was absorbed from medium that had been mixed for two hours at 0 degrees C with either resident or thioglycollate-elicited peritoneal cells, suggesting the presence of receptors for PSF on cells in the population. The addition of pure PSF to populations highly enriched in either resident or elicited adherent peritoneal macrophages resulted in stimulation of macrophages with morphological changes, including increases in size, spreading, vacuolation, and the number of cytoplasmic processes, together with stimulation of proliferation and the phagocytosis of opsonized yeast. PSF also stimulated the incorporation of [3H]thymidine by bone marrow-derived adherent macrophages. Addition of pure PSF to cultures that contained only a single macrophage resulted in enhanced survival and proliferation of these isolated cells, demonstrating that the effect of PSF on macrophages was direct. These results indicate that PSF can stimulate well-differentiated functional macrophages and raise the possibility that the effects of PSF on macrophages may play a regulatory role in immune responses.

Animals↗