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Biomedical subjects

R Henschler

Publications and source records attributed to R Henschler.

45 records · Page 3Linked to original sources
PubMed1991

Expression of functional receptors for interleukin-6 by human polymorphonuclear leukocytes. Downregulation by granulocyte-macrophage colony-stimulating factor.

Surface interleukin-6 receptors were identified on human polymorphonuclear leukocytes (PMNL) by monoclonal anti p80-chain antibody MT 18 Cytoplasmic RNA harvested from PMNL also contained IL-6-R transcripts. Binding of recombinant human (rh) interleukin-6 (IL-6) to IL-6-R bearing PMNL was identified by flow cytometry using phycoerythrin (PE)-conjugated ligand. Treatment of PMNL with rh granulocyte-macrophage colony-stimulating factor (GM-CSF) led to the inability of PMNL to bind MT 18 monoclonal antibody (moAb) and to display binding sites for PE-conjugated rh IL-6. Levels of IL-6-R transcripts in PMNL exposed to GM-CSF were about 5-fold below those of PMNL cultured in medium only. Though a definitive role for IL-6 to modulate the function of PMNL was not found, treatment of PMNL with rh IL-6 clearly resulted in an enhancement of transcript levels of the early response genes c-fos and c-jun in these cells, thus indicating that IL-6 binding is followed by signal transduction.

Antibodies, Monoclonal↗
PubMed1991

Regulation of gene expression of macrophage-colony stimulating factor in human fibroblasts by the acute phase response mediators interleukin (IL)-1 beta, tumor necrosis factor-alpha and IL-6.

Fibroblasts constitute a major element of the bone marrow stroma. They play a pivotal role in blood cell development by providing the scaffolding required for cellular organization and tissue cohesion and by producing soluble molecules including colony stimulating factors (CSFs) and various interleukins regulating hematopoiesis. Our data demonstrate that the acute phase response mediators interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha and IL-6 which are abundantly produced by activated monocytes, enhance levels of macrophage-colony stimulating factor (M-CSF) in fibroblasts by both transcriptional and post-transcriptional mechanisms. The action of these proteins to induce M-CSF transcript levels was dependent on synthesis of new proteins and was not mediated by protein kinase C (PKC) stimulation as depletion of cellular PKC pools by prolonged exposure of fibroblasts to phorbolester TPA did not prevent factor induced synthesis of M-CSF transcripts. However, blockade of PKC by the isoquinoline sulfonamide derivative H7 and thus inhibition of phosphorylation was associated with augmentation of the fibroblasts response to TNF-alpha and IL-6.

Fibroblasts↗
PubMed1991

Regulation of M-CSF expression by M-CSF: role of protein kinase C and transcription factor NF kappa B.

Macrophage-colony-stimulating factor (M-CSF), also referred to as CSF-1, regulates the survival, growth, differentiation and functional activity of monocytes by binding to a single class of high-affinity cell surface receptors, known to be the product of the c-fms protooncogene. The detection of both M-CSF and c-fms expression by cells of the monocyte lineage has suggested that M-CSF may act by an autocrine mechanism. Interestingly, it has been shown that M-CSF can induce the expression of its own gene. Although sensitivity to M-CSF can be modulated by regulation of receptor expression and function, M-CSF responsiveness is largely determined at a postreceptor level. To date, little is known about the intracellular pathway of M-CSF signal transduction. We have therefore investigated the changes in protein kinase C (PKC) activity upon exposure of monocytes to M-CSF. We show that M-CSF activates and translocates PKC. Inhibition of PKC by the isoquinoline derivative H7 abolishes induction of M-CSF by M-CSF. Furthermore, activation of PKC was pertussis-toxin-sensitive and was associated with the detection of an NF kappa B protein in nuclear extracts of M-CSF-induced blood monocytes but not in monocytes exposed to medium treatment only. The results suggest that M-CSF induction of M-CSF involves G proteins, PKC and NF kappa B.

Base Sequence↗
PubMed1991

Screening for expression of cytokines with hematopoietic growth factor activity by permanent human B-cell lines.

Using colony assays in semi-solid media, several investigators have shown that supernatants (SN) of normal and malignant human B-cells can stimulate the growth of granulocyte-macrophage (GM) progenitor cells. So far macrophage colony-stimulating factor (M-CSF) and interleukin-6 (IL-6) have been identified as potential colony-stimulating activity (CSA) present in B-cell SN. However, other CSAs such as GM-CSF, G-CSF, IL-1-beta, IL-3, and IL-4 may also be candidates in this respect. Several human B-cell lines (CL) were screened for the expression of the respective genes at the mRNA and protein level. Constitutive production of GM-CSF was detected in the lymphoblastoid CL Wi-L2-729-HF2 and in the Burkitt line Raji. The signal intensity of specific transcripts and the amount of protein being secreted increased upon exposure to the phorbol ester PMA. The hybridoma line HB-564 also expressed the GM-CSF gene, but required prior stimulation with PMA. 3H-thymidine incorporation of Raji and Wi-L2-729-HF2 cells was unchanged in the presence or absence of a specific neutralizing sheep anti-GM-CSF serum, suggesting that GM-CSF did not serve as an extracellular autocrine growth factor. The expression of the GM-CSF gene was independent of the proliferative state (log phase growth versus plateau phase growth) and of the presence of serum in cultures of the respective CL. The expression of G-CSF, IL-1-beta, IL-3, and IL-4 genes was not detectable in the CL at the mRNA level.

B-Lymphocytes↗
PubMed1991

Induction of c-jun expression in the myeloid leukemia cell line KG-1 by 1-beta-D-arabinofuranosylcytosine.

c-Jun/AP-1 is a transcription factor commonly induced in mammalian cells by serum, phorbol compounds, or peptide growth factors. We show that c-Jun/AP-1 is inducible as well as coordinately regulated, in the human acute myelogenous leukemia cell line KG-1, by the cytostatic drug 1-beta-D-arabinofuranosylcytosine (Ara-C). Concomitantly with Ara-C treatment, growth inhibition and loss of clonogenic survival of KG-1 cells were observed. Whereas KG-1 cells displayed only barely detectable amounts of c-jun transcripts when cultured in the presence of serum, Ara-C at concentrations of 1 to 50 microM induced c-jun transcripts in a dose-dependent fashion. Time course studies showed that 10 microM Ara-C induced c-jun transcripts 6 hr after initiation of culture. Induction of c-jun mRNA was independent of de novo protein synthesis, because the protein synthesis inhibitor cycloheximide failed to alter Ara-C-induced c-jun mRNA accumulation. Furthermore, cycloheximide did not induce c-jun transcripts, ruling out the possibility of posttranscriptional stabilization of c-jun mRNA by labile proteins, as has been previously reported for a variety of serum-inducible protooncogenes and early response genes. Moreover, nuclear run-on analysis disclosed that c-jun induction by Ara-C in KG-1 cells took place at a transcriptional level. Taken together, these findings indicate that c-jun mRNA, unlike its rapid (within minutes) induction by serum in fibroblasts, is induced by Ara-C in KG-1 cells following a much more prolonged time course and is regulated essentially at a transcriptional level.

Cell Survival↗
PubMed1990

Differential regulation of interleukin-6 expression in human fibroblasts by tumor necrosis factor-alpha and lymphotoxin.

The treatment of human diploid fibroblasts with tumor necrosis factor (TNF)-alpha and with lymphotoxin (LT) is associated with induction of interleukin-6 (IL-6) transcripts with TNF-alpha being 10-fold more potent than LT. Here we report on the TNF-alpha/LT-induced signaling mechanisms responsible for the regulation of IL-6 gene expression in these cells. Run-on assays demonstrated that both TNF-alpha and LT increase IL-6 mRNA levels by transcriptional activation of this gene. Stability studies of IL-6 transcripts in fibroblasts showed that TNF-alpha delayed IL-6 mRNA decay but not LT. The induction of IL-6 transcripts by TNF-alpha and LT was not inhibited by the isoquinoline sulfonamide derivative H7. Similarly, depletion of protein kinase C (PKC) by 12-O-tetradecanoyl-phorbol 13-acetate (TPA) did not change the ability of TNF-alpha and LT to induce IL-6 transcripts, demonstrating that stimulation by these agents may not be mediated by activation of PKC. Stimulation of IL-6 transcripts in fibroblasts did also not require new protein synthesis as exposure to the protein synthesis inhibitor cycloheximide (CHX) enhanced accumulation of IL-6 mRNA in the presence or absence of TNF-alpha or LT.

Cells, Cultured↗
PubMed1990

Interleukin-4 regulates mRNA accumulation of macrophage-colony stimulating factor by fibroblasts: synergism with interleukin-1 beta.

We demonstrate that macrophage-colony stimulating factor (M-CSF) is expressed in human fibroblasts at the mRNA and protein level. Following activation with both interleukin (IL)-1 beta and IL-4, fibroblasts synthesized M-CSF transcripts detectable by Northern blot analysis with peak expression occurring at 8 h and 12 h, respectively. Exposure of fibroblasts to both cytokines resulted in M-CSF protein release at 60 h of c. 500 U/ml (for IL-1 beta) and 1000 U/ml (for IL-4), relative to a control preparation of recombinant human M-CSF in a murine bone marrow colony assay. Both interleukins synergized to enhance M-CSF mRNA accumulation and their ability to induce M-CSF transcripts could be abolished by treatment with specific neutralizing antibodies. These observations provide support for the idea that fibroblasts may control monocyte/macrophage development and function, and that IL-1 beta and IL-4 are involved in the regulation of this process.

Blotting, Northern↗
PubMed1990

Sulfotransferase-mediated chlorination of 1-hydroxymethylpyrene to a mutagen capable of penetrating indicator cells.

Methylated polycyclic aromatic hydrocarbons are common in the human environment. Many of them are stronger carcinogens than their purely aromatic congeners. They may be metabolized to benzylic alcohols. We report here on biochemical and toxicological characteristics of 1-hydroxymethylpyrene (HMP), a typical representative of this class of compounds. Rat liver cytosol, fortified with 3'-phosphoadenosine-5'-phosphosulfate, converted HMP into its sulfate ester (HMPS), HMPS bound covalently to isolated DNA. In physiological buffer at 37 degrees C, HMPS had a half-life of 2 min, the major decomposition product being HMP. Thus, cyclic activation is possible. When Cl- anions were present at physiological concentrations, an additional reaction product of HMPS, 1-chloromethylpyrene (ClMP), could be identified on the basis of its chromatographic properties and its mass spectrum, using the authentic standard for comparison. ClMP was shorter-lived in buffer than HMPS. ClMP reacted with DNA, the adduct pattern in the 32P-postlabeling analysis being similar, or identical, to that of HMPS. ClMP proved to be a very potent mutagen in Salmonella typhimurium, whereas HMPS, and HMP in the presence of a sulfate-conjugating system, showed strong mutagenicity only when Cl- or Br- ions were present in the exposure buffer. It is concluded that HMPS is capable of reacting with DNA, but is hampered in its distribution by membrane barriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗