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E Razin

Publications and source records attributed to E Razin.

At least 19 recordsLinked to original sources
PubMed2000

Inhibition of degranulation and interleukin-6 production in mast cells derived from mice deficient in protein kinase Cbeta.

The antigen-mediated activation of mast cells by means of IgE antibodies bound to the cell surface leads to direct interactions between FcepsilonRI receptor cytoplasmic domains and various intracellular proteins. These interactions initiate diverse signal-transduction pathways, and the activation of these pathways results in the immediate release of proinflammatory agents. A delayed response also occurs and includes the release of various cytokines. It is clear that the activation of kinases is a requirement for the exocytosis observed in mast cells. In addition to the tyrosine phosphorylation of the affected system by soluble tyrosine kinases, activity of protein kinase C (PKC) results in serine or threonine phosphorylation of multiple protein substrates. In this study, we found that mast cells derived from PKCbeta-deficient mice produce less interleukin 6 in response to IgE-Ag. The inhibition of exocytosis in the PKCbeta-deficient mast cells occurred whether the stimuli were due to the aggregation of the mast cell surface FcepsilonRI or to the calcium ionophore, ionomycin. However, no significant changes were observed in the proliferative response of the mast cells to interleukin 3 (IL-3) or in their apoptotic rate after IL-3 depletion. (Blood. 2000;95:1752-1757)

Animals↗
PubMed1999

Suppression of microphthalmia transcriptional activity by its association with protein kinase C-interacting protein 1 in mast cells.

Microphthalmia (mi) is a transcription factor that plays a major role in the regulation of growth and function in mast cells and melanocytes. Association of mi with other proteins is a critical step in the regulation of mi-mediated transcriptional activation. We found protein kinase C-interacting protein 1 (PKCI) specifically associated with mi in yeast two-hybrid screening. Immunoprecipitation of mi from quiescent rat basophilic leukemic cells or mouse melanocytes resulted in the specific co-immunoprecipitation of PKCI. This association was significantly reduced on engagement of the surface FcepsilonRI of mast cells or engagement of the Kit receptor on melanocytes. Hence, cell activation caused disengagement of mi from PKCI. Microphthalmia was previously shown to activate the mouse mast cell protease 6 (mMCP-6) promoter. Cotransfection of mi with PKCI in NIH 3T3 fibroblasts containing an mMCP-6 promoter-luciferase reporter demonstrated an up to 94% inhibition of mi-mediated transcriptional activation. PKCI by itself, although localized in the cytosol and nucleus of the cells, has no known physiological function and did not demonstrate transcriptional activity. Its ability to suppres mi transcriptional activity in the transient transfected fibroblast system suggests that it can function in vivo as a negative regulator of mi-induced transcriptional activation.

3T3 Cells↗
PubMed1998

Nuclear translocation of upstream stimulating factor 2 (USF2) in activated mast cells: a possible role in their survival.

Multiple transcription factors are activated in the cytoplasm and translocated to the nucleus where they exert positive or negative control over cellular genes. Such subcellular traffic of transcription factors usually requires the presence of a positively charged nuclear localization sequence (NLS). Upstream stimulating factor 2 (USF2) is one of the few transcription factors that contain two potential domains for nuclear localization. In addition to the conventional basic NLS, USF2 contains a highly conserved USF-specific region that is involved in its nuclear translocation. In the present work, the induction of translocation of USF2 into the mast cell nucleus was observed and found to be dependent on activation of the cells either by IL-3 or IgE-Ag. It was also observed that the prevention of the translocation of USF2 to the nucleus, using a peptide derived from the specific USF-NLS region, significantly inhibited their IL-3-mediated survival. Thus, our findings show a direct connection between mast cell surface receptor-mediated USF2 nuclear translocation and cell viability.

Amino Acid Sequence↗
PubMed1998

Growth-dependent and PKC-mediated translational regulation of the upstream stimulating factor-2 (USF2) mRNA in hematopoietic cells.

Upstream stimulating factor (USF2) is a basic helix-loop-helix leucine zipper transcription factor, which is found in most tissues. A critical role for USF2 in cellular proliferation has been proposed based on its importance in the regulation of various cyclins and P53 and its capability to antagonize c-myc. In this paper we report that IL-3, which is a major growth factor for mast cells, induces USF2 protein synthesis in murine mast cells (MC-9). Surprisingly, it does not significantly affect the level of USF2 mRNA in these cells at any of the time points tested. Using polysomal fractionation and RNA analysis we then demonstrated that this translational regulation is mostly the result of increased USF2 translational efficiency. Moreover, protein kinase C (PKC) inhibitors prevented both the induction of USF2 protein synthesis and the increase in USF2 translational efficiency in IL-3-activated mast cells. Two other hematopoietic cell lines were used to determine whether the translational regulation of USF2 is of a more general nature: mouse lymphosarcoma cells whose proliferation is inhibited by dexamethasone; and mouse erythroleukemia cells that differentiate upon exposure to hexamethylen bisacetamide. In both cell types, USF2 translation was repressed in the non-dividing cells. This strongly implies that USF2 is translationally repressed in quiescent hematopoietic cells. Considering the proposed role of USF in proliferation it seems that translational regulation of USF2 might have an important role in cellular growth.

Animals↗
PubMed1997

Analysis of cytokine profile in human colonic mucosal Fc epsilonRI-positive cells by single cell PCR: inhibition of IL-3 expression in steroid-treated IBD patients.

Mast cells can serve as a possible important source of cytokine production in inflamed tissue which can be regulated by stimuli different from those activating other immune system cells. To study the expression of specific genes in mast cells derived from small human colonic mucosal endoscopic biopsies, we first modified a previously reported procedure to achieve a significantly enriched mast cell fraction. Then, by using single-cell RT-PCR analysis the expression of the IgE Fc receptor (Fc epsilonRI) and c-kit mRNA was determined. It was observed that the Fc epsilonRI-positive cells also expressed c-kit. This observation provided further evidence that Fc epsilonRI-positive cells are indeed mast cells. Analysis of biopsies from 12 patients (four control and eight patients with inflammatory bowel disease (IBD)) was carried out, revealing that all of the Fc epsilonRI-positive cells expressed IL-3, while the expression of IL-4 was detected only in some of these positive cells. TNF alpha was not detected in these cells. Therefore, it would seem that most intestinal mast cells produce IL-3. Since it has been reported that IL-3 synthesis was down-regulated in steroid-treated cells, the expression pattern of IL-3 in intestinal mast cells derived from steroid-treated IBD patients was then determined. IL-3 mRNA was detected in only two out of 24 Fc epsilonRI-positive cells derived from these steroid-treated patients. These results lend strong support to the idea that the down-regulation of IL-3 in mast cells derived from steroid-treated IBD patients occurs in vivo and could be an important mechanism for immunomodulation in IBD.

Biopsy↗
PubMed1997

Microphthalmia (mi) in murine mast cells: regulation of its stimuli-mediated expression on the translational level.

Mice harboring a mutation in the microphthalmia (mi) gene display a variety of abnormalities, including microphthalmia, depletion of skin melanocytes, deafness, a defect in osteoclasts, and a major decrease in mast cell number and function. However, despite the possible critical role played by this protein in mast cell development and function, characterization of its mRNA and protein synthesis in these cells has not yet been performed. In this study, we investigated the regulation of the synthesis of mi in murine mast cells activated by various physiologic stimuli. Using a specific rabbit polyclonal anti-mi antibody, we found that interleukin-3, interleukin-4, or aggregation of the mast cell high-affinity receptor for IgE (Fc epsilonRI) induced the synthesis of mi protein in these cells. None of these stimuli significantly affected the level of mi mRNA in the mast cells at any of the time points tested. Also, using this specific anti-mi antibody, an increase in mi protein synthesis was shown during differentiation of mast cells from their bone marrow cell precursors. Moreover, a complex containing mi bound to upstream stimulating factor 2 was detected only in activated mast cells. We conclude that the regulation of mi expression is on the translational level. Thus, stimulation of mast cells by a variety of stimuli elicits a signaling pathway that regulates mi expression.

Amino Acid Sequence↗
PubMed1996

Murine and human mast cell express acetylcholinesterase.

Expression of catalytically active protein was detected in a murine mast cell line. The primary type of AChE mRNA produced by these cells was found to be the brain and muscle type by PCR amplification of alternative exons from the 3' of mast cells AChE cDNA. AChE was further found to be expressed in the HMC-1 the human mast cell precursor line. Furthermore, utilizing the single cell RT-PCR method we detected AChE mRNA expression in Fc epsilon RI-positive single cells derived from human colonic mucosal biopsies. Our findings predict the involvement of mast cell AChE in neuronal-mast cell interactions.

Acetylcholinesterase↗
PubMed1996

Aggregation of the Fc epsilon RI in mast cells induces the synthesis of Fos-interacting protein and increases its DNA binding-activity: the dependence on protein kinase C-beta.

The ability of c-Fos to dimerize with various proteins creates transcription complexes which can exert their regulatory function on a variety of genes. One of the transcription factors that binds to c-Fos is the newly discovered Fos-interacting protein (FIP). In this report we present evidence for the regulation of the synthesis of FIP by a physiological stimulus. We found that the aggregation of the mast cell high affinity receptor for IgE (Fc epsilon RI) induced the synthesis of FIP and increased its DNA binding activity. Moreover, down-regulation of the isoenzyme protein kinase C-beta (PKC-beta) by a specific antisense phosphorothioate oligonucleotide resulted in profound inhibition of FIP-Fos DNA binding activity. Thus, aggregation of the Fc epsilon RI on mast cells elicits a PKC-beta dependent signaling pathway which regulates FIP-Fos DNA binding activity.

Animals↗
PubMed1995

Fecal excretion of leukotriene C4 during human disease due to Shigella dysenteriae.

Fecal excretion of leukotriene C4 was determined in 26 individuals with dysentery and in 19 healthy controls. Of the patients, five were infected with Shigella dysenteriae type 1, 15 were infected with Shigella flexneri, two were infected with Shigella boydii, and four were infected with Shigella sonnei. Three of the healthy controls were infected with non-dysenteriae Shigellae. All isolates of Shigella dysenteriae type 1 produced Shiga toxin; the other strains were not toxigenic. Patients with dysentery due to Shigella dysenteriae type 1 excreted higher concentrations of leukotriene C4 (median, 3,234 pg/0.05 g of feces) than either ill individuals infected with non-dysenteriae Shigellae (median, 202 pg/0.05 g) or healthy carriers (median, 145 pg/0.05 g) and uninfected controls (median, 129 pg/0.05 g). We propose that Shiga toxin stimulates intestinal mast cells, which release leukotriene C4, contributing to the inflammatory response in Shigella dysenteriae type 1-associated dysentery.

Adult↗
PubMed1994

Protein kinases C-beta and C-epsilon link the mast cell high-affinity receptor for IgE to the expression of c-fos and c-jun.

In this report we identify the specific isozymes of protein kinase C (PKC) that are involved in c-fos and c-jun mRNA accumulation in the rat basophilic leukemia cell line RBL-2H3. These cells could be largely depleted of the endogenous PKC isozymes by chronic treatment with phorbol 12-myristate 13-acetate followed by permeabilization of the cells with streptolysin O. The reconstitution of these cells with defined concentrations of either PKC-beta or PKC-epsilon up to 10 nM and 20 nM, respectively, induced c-fos and c-jun in a dose-dependent manner. At high concentrations of PKC-beta and -epsilon the induction of c-fos and c-jun was independent of the aggregation of the high-affinity IgE receptors (Fc epsilon type I receptors). In contrast, at limiting concentrations of these two PKC isozymes, 1 nM, the increase in c-fos and c-jun mRNAs was dependent on the aggregation of the Fc epsilon type I receptors. Unlike PKC-beta and -epsilon, PKC-alpha and PKC-delta failed to reconstitute c-fos and c-jun induction at any dose over the range examined. We conclude that PKC-beta and PKC-epsilon serve as a link between the cell surface receptor and gene expression.

Animals↗
PubMed1994

Enhancement of interleukin-3-dependent mast cell proliferation by suppression of c-jun expression.

We have previously shown that protein kinase C (PKC) depletion is associated with an increase in the proliferation of interleukin 3 (IL-3)-induced mast cells. Here we show that the AP-1 components c-Jun and c-Fos are induced by IL-3. While c-Jun's induction by IL-3 is totally dependent on PKC, c-Fos induction by IL-3 is only attenuated by PKC depletion. AP-1 binding activity was also induced by IL-3 but this induction was PKC independent. These results indicated a possible involvement of c-Jun in the inhibition of IL-3-induced growth regulation. A support for this assumption came from experiments in which an increase in thymidine incorporation into mast cells was noted when c-jun antisense oligomers were administered to IL-3-treated cells. Since the only known effect of direct inhibition of c-Jun on proliferation rates in several cellular systems was a reduction of proliferation, we verified that our c-jun antisense oligomer could also inhibit proliferation rates in fibroblasts where such a repression was previously reported. Thus c-Jun has an inhibitory effect on IL-3 induction of mast cells proliferation that is distinct from its role in several other cellular environments. These observations reveal the involvement of AP-1 and its components in IL-3-induced signal transduction and the importance of the mast cell environment in determining their specific cellular function.

Animals↗
PubMed1993

Regulation of AP-1 expression and activity in antigen-stimulated mast cells: the role played by protein kinase C and the possible involvement of Fos interacting protein.

We have recently observed that protein kinase C (PKC) was involved in the regulation of the accumulation of mRNAs of the AP-1 components in cultured Abelson-transformed murine fetal-liver-derived mast cells stimulated by exocytotic stimuli. Here we analyzed the probable regulatory effect of PKC on the synthesis and DNA-binding activity of AP-1 complexes in immunologic stimulated mast cells. In this study we used the interleukin-3--dependent murine fetal-liver--derived mast cells that were not transformed by the Abelson oncogene. Study of PKC-depleted cells showed PKC dependency of c-fos mRNA accumulation and protein expression in IgE-Ag stimulated cells. In contrast, the c-jun mRNA accumulation was unaffected by PKC depletion, whereas its protein expression was dependent on this enzymatic activity. This suggests the involvement of PKC in the regulation of translation of c-Jun, a level of c-Jun regulation that was not previously described. The amount of AP-1 DNA-bound complex was also lowered in PKC-depleted cells. Therefore, PKC plays an important regulatory role in different stages of the signal transduction pathway because of IgE-Ag stimulation. Surprisingly, we have observed that although the amount of total synthesized c-Fos began to increase 15 minutes after immunologic stimulation, the amount of c-Fos associated with Juns did not increase, even after 45 minutes. This association was not affected by PKC. Using a Fos-interacting protein (FIP)-cDNA probe, an expression of 2.9 kb mRNA was detected in these cells. Furthermore, immunologic stimulation caused an increase in the amount of a Fos-containing protein complex that bound to an FIP-binding DNA oligonucleotide. Therefore, we propose that this protein complex that contains most of the immunologically induced c-Fos has an important role in IgE-Ag-stimulated signal transduction.

Animals↗
PubMed1993

Serum modulates mast cell responses to IgE antigen stimulation.

Serum induces the expression of the fos and jun gene families, which encode the transcription factor AP-1. Since we previously found that activation of mast cells by IgE-antigen (Ag) induces the mRNA accumulation of c-fos, c-jun, junB and junD proto-oncogenes, we were prompted to investigate whether serum could affect such accumulation in these cells. In addition, we investigated whether serum could modulate inhibition of DNA synthesis in immunologically stimulated mast cells. Mast cells, which were cultured in the presence of fetal calf serum (FCS), were characterized by a high proliferation rate and high accumulation of the mRNA of c-fos, junB and junD proto-oncogenes. After sustained FCS deprivation both DNA synthesis and the level of c-fos mRNA were significantly decreased, as expected, whereas the level of c-jun, junB and junD mRNA were not affected. As opposed to mast cells which were cultured in the presence of FCS, immunological stimulation of FCS-deprived cells resulted in DNA synthesis inhibition and an increase in c-fos expression. The results also show that the level of c-fos mRNA was increased by either IgE-Ag or FCS up to a similar level, while these two triggers could not act synergistically to enhance this expression further. Thus, changes in DNA synthesis, induced by FCS, block the ability of the immunological challenge to inhibit mast cell growth and to enhance c-fos mRNA accumulation.

Animals↗
PubMed1993

5-fluorouracil and mast cell precursors in mice.

In the mouse hematopoietic system, 5-fluorouracil (5-FU) reversibly inhibits the generation of multilineage colonies containing granulocyte, erythroid, megakaryocyte, and macrophage lineage. To determine the effect of 5-FU on mastopoiesis in vitro, bone marrow cells were obtained from mice, cultured, and treated with 5-FU for 14 days in an interleukin-3 (IL-3)-enriched medium. A dose-related inhibitory effect of 5-FU on mastopoiesis was found. When an inhibitory dose (1 microgram/mL) of 5-FU was supplemented to the cultures for only 2, 4, or 8 days and the cells were then recultured without the drug, we observed inhibition of mastopoiesis directly related to the time of exposure of the cells to 5-FU. To determine the effect of 5-FU on mastopoiesis in vivo, bone marrow cells from mice that had received a single intravenous (i.v.) 5-FU injection (150 mg/kg) were cultured. A virtually total absence of mast cells was noted at days 1 and 2 following 5-FU administration. A gradual reappearance of mast cells was later observed. Whether mice were injected with the drug once or with four once-daily (100 mg/kg 5-FU) injections, a similar pattern of delay of mast cell appearance was observed. The findings suggest (1) an irreversible, nonadditive, toxic effect of 5-FU on mast cell precursors and (2) that most or all of the mast cell precursors are nonquiescent cells, continuously activated or cycling. In addition, the use of 5-FU may serve as a unique model system for controlling and studying mastopoiesis in normal mice, rather than the mutated mice currently studied.

Animals↗
PubMed1991

Protein kinase C regulates proliferation of mast cells and the expression of the mRNAs of fos and jun proto-oncogenes during activation by IgE-Ag or calcium ionophore A23187.

Short-term stimulation (up to 16 hours) of interleukin-3 (IL-3)-dependent mouse bone marrow-derived mast cells, Abelson transformed mouse liver-derived mast cells, or rat basophilic leukemia cells by either IgE-Ag or calcium ionophore A23187 resulted in inhibition of their proliferation as measured by 3H-thymidine incorporation and MTT (tetrazolium) assays, and in accumulation of the mRNAs of c-fos, c-jun, junB and slightly of junD proto-oncogenes. The involvement of protein kinase C (PKC) in these responses was investigated by using several approaches of enzyme activity regulation. Direct activation of the PKC was achieved by short-term exposure of the cells to the PKC-specific activator phorbol 12-myristate-13-acetate (PMA). Inhibition of PKC activity was obtained by either prolonged treatment of the cells with PMA or by exposure of the cells to the PKC inhibitors H-7 and staurosporine. The results showed the following: (1) Short-term exposure of mast cells to PMA was sufficient to induce inhibition of proliferation. (2) An increase in PKC activity was associated with a decrease in the proliferation of IgE-dinitrophenol (DNP) or calcium ionophore A23187-stimulated cells. (3) A direct correlation was found between the increase in PKC activity and the increase in the level of the mRNAs of the jun proto-oncogenes in cells activated by both stimuli mentioned. (4) While an increase in PKC activity was associated with the upregulation of the level of c-fos mRNA during calcium ionophore A23187 stimulation, it showed the opposite effect on the expression of the mRNA of this proto-oncogene when the cells were triggered by IgE-DNP. Therefore, we concluded that PKC plays various roles in the expression of the mRNA of c-fos in activated mast cells depending on the stimulus involved. In addition, the expression of the mRNA of c-jun and junB proto-onogenes is not coordinately regulated with that of c-fos during immunologic stimulation. This discordancy, which is associated with the increase in PKC activity in mast cells, may play a role in the regulation of the transcription of AP-1-responsive genes, and therefore could be associated with the regulation of proliferation of these cells.

Animals↗