Recombinant human interleukin 6 (B-cell stimulatory factor 2) is a potent inducer of differentiation of mouse myeloid leukemia cells (M1)

AbstractRecombinant human interleukin 6 (IL-6), a lymphokine involved in the final differentiation of activated B-cells into antibody-forming cells, greatly suppressed proliferation and induced differentiation of murine myeloid leukemia cells (M1) into mature macrophage-like cells. When M1 cells were treated with IL-6, their growth was completely arrested as early as on day 2, and they were induced to differentiate morphologically into macrophage-like cells. Differentiation-associated properties such as phagocytic activity, adherence to the dish surface, Fc and C3 receptors, were also induced within 24 h by IL-6, and they reached their respective maximal levels on day 2 or 3. The potency of IL-6 in suppressing proliferation and inducing differentiation was much greater than that of 1α,25-dihydroxyvitamin D3 one of the most potent inducers of M1 cells. The present report indicates that IL-6 is involved in the differentiation of not only B-cells but also myeloid leukemia cells

Molecular cloning of a novel gene involved in serotonin receptor-mediated signal transduction in rat stomach

AbstractIn Xenopus oocytes injected with small size mRNAs (500–700 b), obtained from rat stomach by fractionation, application of 10 μM 5-HT induced a substantial Ca2+-activated Cl− current (ICl-Ca). ICl-Ca was not elicited by 5-HT in native oocytes. Consistent results from this assay in the oocyte expression system motivated cDNA cloning experiments. A novel cDNA (named r at s tomach s erotonin receptor-related cDNA: RSS cDNA) which encodes a small protein involved in specific 5-HT receptor-mediated ICl-Ca activation was identified. The molecular weight of RSS protein in the reticulocyte lysate translation system (∼10 kDa) is identical to that calculated from the amino acid sequence. Computer-aided analysis of the predicted protein does not show any obvious sequence homologies (<18%) to any other proteins including G protein-coupled receptors. Northern analysis revealed that RSS mRNA is ubiquitously expressed at varying levels in a number of different tissues. Furthermore, the binding of [3H]spiperone, a 5-HT2 receptor antagonist, was examined in CHO cells, which highly expressed RSS transcripts (named CHO-RSS). Specific binding of [3H]spiperone was not clearly observed in native CHO but was detected in CHO-RSS. The dissociation constant was 10.3 nM in CHO-RSS. These results suggest that RSS protein may be a factor which facilitates 5-HT receptor expression or, alternatively, an enhancer of the affinity of native 5-HT receptor to 5-HT

C/EBP homologous protein (CHOP) up-regulates IL-6 transcription by trapping negative regulating NF-IL6 isoform

AbstractInterleukin-6 (IL-6) production is up-regulated by several stimuli through the activation of transcription factors. We have previously demonstrated that CCAAT/enhancer binding protein homologous protein (CHOP) positively regulates IL-6 production at the transcriptional level in the human melanoma cell line A375. In this study, we provide evidence that CHOP up-regulates the IL-6 transcription without binding to the IL-6 promoter. CHOP dimerized more preferentially with an inhibitory isoform of nuclear factor for IL-6 expression (LIP (liver-enriched inhibitory protein)) than with a positively acting isoform (LAP, liver-enriched activator protein). These results indicate that CHOP plays an important role in IL-6 production without binding to its promoter, probably by trapping protein(s) such as LIP, which would otherwise inhibit IL-6 transcription

Simple Fibroblast-Based Assay To Test the Pyrazinamide Susceptibility of Mycobacterium tuberculosis

A simple fibroblast-based assay (SFA) was found to be efficient in evaluating the susceptibilities of clinical isolates of Mycobacterium tuberculosis to pyrazinamide (PZA). Forty-five clinical isolates were examined. The MICs of PZA for susceptible strains in an SFA were between 3.13 and 12.5 μg/ml, and the MICs of PZA for resistant strains were more than 100 μg/ml