Biomedical subjects

M Bouaboula

Publications and source records attributed to M Bouaboula.

29 records · Page 2Linked to original sources

PubMed1995

IL-1 stimulates a diverging signaling pathway in EL4 6.1 thymoma cells. IL-2 release, but not IL-2 receptor expression, is sensitive to pertussis toxin.

We reassessed the involvement of Bordetella pertussis toxin (PTX)-sensitive proteins in the IL-1 signaling pathway on the responses induced by IL-1 on the murine thymoma cell line EL4 6.1. We demonstrate that the ADP-ribosyltransferase activity of PTX, and not its cell-anchoring B oligomer part, is responsible for the inhibition of IL-1-induced IL-2 release, since 1) the concentration of PTX (< or = 1 ng/ml) required to block the secretion is 100 to 1000 times lower than the concentration needed with the B oligomer; and 2) the mutated PT-9K/129G, devoid of ADP-ribosyltransferase activity, was inactive at 100 ng/ml. We found that partial ADP-ribosylation of the Gi2/Gi3 proteins before stimulation with IL-1 was sufficient to obtain full inhibition of IL-2 release. PTX did not however inhibit the appearance on the cell surface of the high affinity IL-2 receptors or the IL-2 release induced by PMA. In addition, we show that PTX prevented the expression of the IL-2 mRNA induced by IL-1, without affecting the binding of IL-2 specific nuclear factors to the T cell distal element of the IL-2 promoter. Furthermore, PTX also inhibited IL-1-induced proliferation of non-transformed thymocytes. In conclusion, our results demonstrate that IL-1-induced IL-2 release is sensitive to PTX-catalyzed ADP-ribosylation and that IL-1 activates a diverging pathway on EL4 6.1 cells.

Animals↗

PubMed1995

Stimulation of cannabinoid receptor CB1 induces krox-24 expression in human astrocytoma cells.

The recent isolation and cloning of the G protein-coupled central cannabinoid receptor (CB1) from brain tissue has provided a molecular basis to elucidate how cannabinoid compounds may mediate their psychoactive effects. Here we report the high expression of cannabinoid receptors in human astrocytoma tumors of different grades, in the astrocytoma cell lines U373 MG and GL-15, as well as in normal astrocytes. From an analysis of the coupling mechanisms of functional CB1 receptors in U373 MG, we show that, in addition to the inhibition of adenylyl cyclase, activation by the cannabinoid agonist CP-55940 induces the expression of the immediate-early gene krox-24, also known as NGFI-A, zif/268, egr-1, and TIS8. The amount of Krox-24 protein and the level of Krox-24 DNA binding activity, as measured by Western blot and electrophoretic mobility shift assay, respectively, were also increased by the addition of CP-55940. These effects were blocked by incubation with pertussis toxin but not by treatment with hydrolysis-resistant cAMP analogues, suggesting that the transduction pathway between the cannabinoid receptor and krox-24 involves a pertussis toxin-sensitive GTP-binding protein and is independent of cAMP metabolism. The specific involvement of CB1 in Krox-24 induction was demonstrated in Chinese hamster ovary cells transfected with the human CB1 receptor and also in experiments using the CB1-selective cannabinoid antagonist SR 141716A.

Animals↗

PubMed1995

Enhancement of endotoxin-induced interleukin-10 production by SR 31747A, a sigma ligand.

SR 31747A is a new sigma ligand eliciting immunosuppressive and anti-inflammatory properties. Here, we show that SR 31747A greatly enhances lipopolysaccharide (LPS)-induced systemic release of interleukin (IL)-10, while it inhibits the secretion of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. In line with this finding, we also show by using quantitative reverse transcription-polymerase chain reaction analysis that SR 31747A increased LPS-induced IL-10 mRNA accumulation in spleen cells, whereas the level of both TNF-alpha and IFN-gamma mRNA was dramatically decreased. The enhancement of IL-10 production by SR 31747A treatment was also apparent in nude and severe-combined immunodeficient mice treated with LPS, clearly indicating that T and B cells were not involved. Finally, SR 31747A conferred protection against the lethal effect of LPS. The finding that SR 31747A strongly stimulates the synthesis of the natural anti-inflammatory cytokine IL-10, a property not observed with dexamethasone, provides new insights for the clinical use of this original compound, particularly in chronic inflammatory diseases where IL-10 is believed to be a pivotal regulatory component.

Animals↗

PubMed1995

The sigma ligand SR 31747 prevents the development of acute graft-versus-host disease in mice by blocking IFN-gamma and GM-CSF mRNA expression.

SR 31747 is a sigma ligand which prevents the development of acute graft-versus-host reaction (GvHR) in hybrid B6D2F1 mice injected with C57BL/6 parental spleen cells. In the present study, we showed that this drug dramatically impaired the GvHR-associated increase in the numbers of both B-lymphocytes and polymorphonuclear cells (PMNs) in the spleen. Because SR 31747 blocked the GvHR-induced expression of both interleukin-2 and transferrin receptors on T-lymphocytes, it is very likely that this molecule prevented the disease through an inhibition of T-lymphocyte activation. Cytokine messenger RNA analyses on spleen cells revealed that SR 31747 blocked IFN-gamma and GM-CSF but not IL-4 transcription. These effects, which are different from those observed with either cyclosporin-A or dexamethasone, strongly suggest that SR 31747 preferentially inhibits the Th1 lymphocyte subset.

Acute Disease↗

PubMed1994

Regulation of 5-hydroxytryptamine2 (5-HT2) receptor expression in cultured rat aortic smooth muscle cells by SR 46349B, a selective 5-HT2 receptor antagonist.

Regulation of 5-hydroxytryptamine (5-HT2) receptor expression by SR 46349B, a potent and selective 5-HT2 receptor antagonist, was investigated in cultured rat aortic smooth muscle cells. Binding of [3H]SR 46349B to rat vascular smooth muscle cells was time-dependent, reversible, and saturable. [3H]SR 46349B bound to one class of specific binding sites with high affinity (KD = 1.3 +/- 0.3 nM; Bmax = 176 +/- 42 fmol/10(5) cells). Exposure of cells to a 1 microM concentration of the 5-HT2 agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ((+/-)-DOI) or the antagonist ketanserin led to a significant decrease in 5-HT2 receptor density as measured by [3H]SR 46349B binding. In contrast, exposure of cells to 1 microM SR 46349B caused a marked increase in the maximal binding capacity of [3H]SR 46349B, with a maximal effect at 24 h (73% increase). The affinity constant was not affected by prior exposure to (+/-)-DOI, ketanserin, or SR 46349B. Furthermore, exposure of cells to 1 microM (+/-)-DOI or ketanserin produced, 48 h later, a decrease in the ability of (+/-)-DOI to stimulate phosphoinositide turnover in the cells, whereas treatment with SR 46349B induced a significant stimulation of the 5-HT2 receptor-linked signal transduction. This effect occurred with no changes in the amount of 5-HT2 receptor mRNAs as measured by quantitative polymerase chain reaction. These results indicate that SR 46349B increases 5-HT2 receptor binding and functions without altering steady-state 5-HT2 mRNA levels in cultured rat aortic smooth muscle cells.

Amphetamines↗

PubMed1993

Peripheral benzodiazepine receptor modulation with phagocyte differentiation.

Peripheral benzodiazepine receptor (PBR) was found to be less expressed in the immature phagocytic HL-60 and U-937 cell lines than in the more mature monocytic THP-1 cell line. Cell differentiation by several agents induced a strong enhancement of PBR density on these three phagocytic cell lines but not on the lymphocytic CEM cell line. Detailed analysis of phorbol 12-myristate 13-acetate-treated THP-1 cells showed an increased PBR expression and the rise came along with an increase of CD11a and CD11b antigens and a secretion of macrophagic cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta and IL-8. Quantitation of mRNA using polymerase chain reaction (PCR)-based technique showed that overexpression of PBR did not parallel mRNA expression, indicating a gene-independent regulation. These results suggest that PBR predominance on phagocytic cells could be related to maturation process.

Antigens, CD↗

PubMed1993

Up-regulation of 5-HT2 receptors in the rat brain by repeated administration of SR 46349B, a selective 5-HT2 receptor antagonist.

Chronic administration (twice a day for three days and on the morning of the fourth day) of SR 46349B (trans-4-[(3Z)3-(2-dimethylaminoethyl)oxyimino-3-(2-fluoroph enyl)propen-1- yl]phenol hemifumarate) (10 mg/kg, orally), a selective 5-HT2 receptor antagonist, caused 24 h later a marked increase (+42%) of the maximum binding capacity of [3H]ketanserin in rat brain cortical membranes without change in its affinity constant. Further, administration of the 5-HT2 receptor agonist, (+/-)-DOI((+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane) (1 mg/kg, i.p.), produced in chronic SR 46349B treated rats a significant increase in the amount of [3H]-inositol phosphate compared to corresponding controls. In addition, subacute administration of SR 46349B caused a 2-fold increase in the head-twitch response to (+/-)-DOI (0.5 mg/kg, i.p.). This enhanced response was blocked by an acute administration of ritanserin (6-(2-[4-[bis(4-fluorophenyl)methylene]-1-piperidinyl]ethyl]-7- methyl-5H-thiazolo[3,2-a]pyrimidin-5-one) (10 mg/kg). Finally, a significant enhancement (+29%) of 5-HT2 receptor mRNA levels was observed in the cortex. Taken together, these data showed that an up-regulation of 5-HT2 receptors occurred in rats following repeated treatment with a selective 5-HT2 receptor antagonist. The effects of SR 46349B on 5-HT2 receptors might implicate pre-translational regulation.

Amphetamines↗

PubMed1993

Cannabinoid-receptor expression in human leukocytes.

Marijuana and many of its constituent cannabinoids influence the central nervous system (CNS), probably through the cannabinoid receptor, which has recently been cloned in rat and human. While numerous reports have also described effects of cannabinoids on the immune system, the observation of both mRNA and cannabinoid receptor has hitherto been exclusively confined to the brain, a reported detection in the testis being the sole example of its presence at the periphery. Here we report the expression of the cannabinoid receptor on human immune tissues using a highly sensitive polymerase-chain-reaction-based method for mRNA quantification. We show that, although present in a much lower abundance than in brain, cannabinoid receptor transcripts are found in human spleen, tonsils and peripheral blood leukocytes. The distribution pattern displays important variations of the mRNA level for the cannabinoid receptor among the main human blood cell subpopulations. The rank order of mRNA levels in these cells is B cells > natural killer cells > or = polymorphonuclear neutrophils > or = T8 cells > monocytes > T4 cells. Cannabinoid-receptor mRNA, which is also found in monocytic, as well as T and B leukemia cell lines but not in Jurkat cells, presents a great diversity of expression on these cells as well, B-cell lines expressing a much higher level than T-cell lines. The cannabinoid receptor PCR products from leukocytes and brain are identical both in size and sequence suggesting a strong similarity between central and peripheral cannabinoid receptors. The expression of this receptor was demonstrated on membranes of the myelomonocytic U937 cells using the synthetic cannabinoid [3H]CP-55940 as ligand. The Kd determined from Scatchard analysis was 0.1 nM and the Bmax for membranes was 525 fmol/mg protein. The demonstration of cannabinoid-receptor expression at both mRNA and protein levels on human leukocytes provides a molecular basis for cannabinoid action on these cells.

Animals↗

PubMed1993

Distribution profile and properties of peripheral-type benzodiazepine receptors on human hemopoietic cells.

The cellular localization of peripheral-type benzodiazepine receptors (PBRs) was characterized in several human blood cell subpopulations including erythrocytes, platelets, monocytes and polymorphonuclear neutrophils (PMN), B, NK, T8 and T4-cells. Pharmacological properties of the PBR were established by binding studies and PBR mRNA expression was measured by quantitative polymerase chain reaction based method. These data clearly indicate 1) the PBR is pharmacologically homogeneous in the various types of blood cells, 2) the rank order of PBR cell density is monocytes = PMN > lymphocytes >> platelets > erythrocytes, 3) the PBR appears to be transcriptionally regulated since mRNA levels are roughly correlated with PBR density.

Antibodies, Monoclonal↗

PubMed1992

Standardization of mRNA titration using a polymerase chain reaction method involving co-amplification with a multispecific internal control.

We describe a simplified and reliable polymerase chain reaction-based method for assaying RNAs of low abundancy. The technique involves the co-amplification of cellular RNA-derived cDNA with a multispecific cDNA of synthetic origin added as an internal standard, using primer pairs common to both templates. We show that the co-amplified templates accumulate in a parallel manner throughout both the exponential and nonexponential phases of amplification, even when the starting amounts of the templates differ by up to 2 orders of magnitude. This finding means that preliminary experiments designed to determine either the late exponential region or the amplification efficiency for each pair of primers are unnecessary. This has enabled us to develop a greatly simplified quantitation protocol. We illustrate our approach by quantifying the effect of the immunosuppressor cyclosporin A on the accumulation of interleukin-4, interferon-gamma, and interleukin-2 receptor mRNAs in phytohemagglutinin-stimulated human peripheral blood mononuclear cells.

Base Sequence↗

PubMed1992

Contrasting effects of the protein kinase C inhibitor staurosporine on the interleukin-1 and phorbol ester activation pathways in the EL4-6.1 thymoma cell line.

EL 4-6.1 cells, variants of the murine EL4 thymoma cell line, can be activated by interleukin 1 (IL-1) or phorbol 12-myristate-13-acetate (PMA), or PMA+IL-1 to secrete interleukin 2 (IL-2) and interleukin 4 (IL-4) and to express the IL-2 receptor (IL-2R). To compare the different activation pathways, we examined the effects of staurosporine (STAR) and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), two protein kinase C (PKC) inhibitors, on the induction of interleukin secretion and IL-2R expression in these cells. We report here that nanomolar concentrations of STAR strongly potentiated (20- to 30-fold) the production of IL-2 or IL-4, when EL 4-6.1 cells were induced by IL-1 alpha (or IL-1 beta) alone. By contrast, at identical concentrations, STAR dose-dependently inhibited the production of IL-2 and IL-4 resulting from PMA or PMA+IL-1 cell treatment. STAR also negatively affected the expression of IL-2R, which was dependent on PMA-sensitive PKC with either IL-1, PMA, or PMA+IL-1 stimulation. The changes in interleukin production and IL-2R expression in EL 4-6.1 activated cells were correlated with changes at the mRNA level measured by quantitative polymerase chain reaction (PCR). This finding suggests a pretranslational effect of the drug. At micromolar concentrations, H7 showed the same effects as STAR, but only increased IL-1-triggered interleukin secretions twofold. We observed that the action of PKC inhibitors did not result from modification of IL-1 receptor (IL-1R) expression in EL 4-6.1 cells. Thus, our data show that PKC inhibitors clearly distinguish between IL-1 and PMA stimulatory pathways. In addition, they suggest that the IL-1 stimulatory pathway involves PKC(s) [or other undefined kinase(s)] which regulate this pathway and differ from PKC(s) activated by PMA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗