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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription factor E2F binds to cellular promoters of certain growth- and cell cycle-controlling genes and forms distinct heteromeric complexes with other nuclear proteins. We show here that alpha and beta interferons (alpha, beta) and interleukin-6 abolished the E2F-containing DNA-binding complexes in Daudi Burkitt lymphoma cells and in M1 myeloblastic cells, which responded to the cytokines by suppression of c-myc transcription. Time kinetics studies showed that the abolishment of E2F complexes coincided with reduction of c-myc expression and that both molecular events preceded the cell cycle block in G0/G1 phase. In contrast, the pattern of E2F complexes remained unchanged in an interferon-treated growth-resistant Daudi cell mutant that displayed relaxed regulation of c-myc. All of the DNA-binding E2F complexes, including those containing the retinoblastoma protein (pRB), cyclin A-p33cdk2, and the free forms of E2F, were reduced by interferons or interleukin-6. Their abolishment was unperturbed by pharmacological treatments that alleviated the cyclin A and pRB responses to interferon. Thus, changes in cyclin A expression and pRB phosphorylation are not primary events that influence the pattern of E2F responses to cytokines. Addition of EDTA to cell extracts of interferon-treated Daudi cells restored the DNA-binding activity of E2F, resulting in the appearance of a single E2F complex that exclusively contained pRB. It is suggested that the regulation of E2F by growth-inhibitory cytokines that induce cell cycle exit takes place at the level of the DNA-binding activity, and by that mean it differs basically from the phase-specific regulation of E2F in cycling cells.
Mol Cell Biol 1993 Sep
PMID:Interferons and interleukin-6 suppress the DNA-binding activity of E2F in growth-sensitive hematopoietic cells. 768 48

Interleukin-6 bioactivity (IL-6) has been shown to be present in Sertoli cells. To further characterize the IL-6 in the seminiferous epithelium, the IL-6 like-antigen was detected, stage-specific basal distribution of IL-6-like bioactivity and its regulation by FSH, cAMP and TPA was characterized in isolated, rat seminiferous tubule segments. In addition, the effects of human recombinant IL-6 on stage-specific DNA synthesis was investigated. Both monoclonal and polyclonal antibodies recognized M(r) 22 and 23 kDa of IL-6 like immunoreactivity in the seminiferous epithelium. The basal IL-6 production showed high levels during stages XIII-XIV-I-V, low during VII and VIII. FSH stimulated IL-6 production at nearly all stages and most significantly at stage VII of the cycle. Human recombinant IL-6 dose-dependently inhibited the onset of meiotic DNA synthesis of preleptotene spermatocytes, and a minor inhibition was found on advanced (A3-type B) spermatogonia. These results support the hypothesis that IL-6 is a stage-specific paracrine regulator of the seminiferous epithelium exerting a specific inhibitory action on meiotic DNA synthesis.
Mol Cell Endocrinol 1995 Feb 27
PMID:Function of interleukin-6 as an inhibitor of meiotic DNA synthesis in the rat seminiferous epithelium. 775 35

Infections, trauma and inflammatory processes induce a host response with increases in a large group of structurally and functionally diverse plasma proteins. Parental administration of foreign proteins also induce an increase in plasma fibrinogen. Interleukin-6 (IL-6) is a monocyte-derived mediator and has regulatory effects on acute phase protein genes which result in the induction of fibrinogen synthesis in primary hepatocytes, while the addition of interleukin-1 (IL-1) exerts a negative modulating influence on the IL-6-stimulated fibrinogen. In order to understand the mechanisms by which IL-1 inhibits IL-6-stimulated fibrinogen transcription and translation, and since IL-1 is believed to act through PGE2 stimulation, we have studied the influence of PGE2 in IL-6 or IL-1, alone and in combination, on Fg mRNA expression (by Northern blot analysis) and the influence of PGE2, indomethacin, and arachidonic acid on Fg secretion. Moreover, since human recombinant interleukin-1 receptor antagonist (hrIL-1ra) is a strong inhibitor of IL-1 induced IL-1 transcription and translation and has an inhibitory effect on PGE2, we have studied the effects of IL-1ra on the down-regulation of IL-6 stimulated fibrinogen by IL-1, using an Fg ELISA method.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1995 Jan 26
PMID:The down-regulation of IL-6-stimulated fibrinogen steady state mRNA and protein levels by human recombinant IL-1 is not PGE2-dependent: effects of IL-1 receptor antagonist (IL-1RA). 777 69

The present study was performed on primary cultures of mouse astrocytes and cultures of rat pheochromocytoma PC-12 in order to investigate the regulation of the prion protein (PrP) gene expression in relation to proliferation and differentiation. Treatment of PC-12 cells with interleukin-6 (IL-6) and beta-nerve growth factor (NGF) resulted in induction of neuronal differentiation. Northern blot analysis demonstrated a 4-fold increase of PrP mRNA in relation to cellular differentiation, after 7 days of treatment with either of the two factors. In astrocytes, PrP and glial fibrillary acidic protein (GFAP) mRNA levels were found to be regulated in a similar manner during development in vitro. A 3-fold increase of their mRNAs was observed from 5 to 14 days of culture (proliferation period). Then, their gene expressions showed a slight decrease from 14 to 28 days (maturation period). Treatment of astrocytes with IL-6, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) appeared to markedly down-regulate the expression of GFAP mRNAs, which might reflect cell maturation. In contrast, they had no significant effect on the expression of PrP gene. These results suggest that the PrP gene expression is differently regulated in neural cells. In neuronal cells, it is mainly associated with differentiation. On the other hand, in astrocytes, the PrP mRNA level seems to be not only related to the proliferation and differentiation stages.
Brain Res Mol Brain Res 1994 Mar
PMID:Modulation of prion protein gene expression by growth factors in cultured mouse astrocytes and PC-12 cells. 791 3

The ability of interleukin-1 (IL-1) to activate diverse cell populations supports its role as a preeminent cytokine in the pathogenesis of chronic inflammation. In this study, we investigated the role of Il-1 and IL-1 receptor antagonist protein (IRAP) in the regulation of allergen-induced synthesis of IgE and proinflammatory cytokines. The temporal expression of IL-1 beta and IRAP during 5-day allergen-activated peripheral mononuclear cell (PMNC) cultures suggested differential production of the two cytokines. To determine the influence of IRAP on IL-1-mediated cellular responses, we cultured PMNC from allergic donors with specific allergens in the presence or absence of IRAP pretreatment. Culture supernatants were assayed for IgE and cytokines using specific enzyme-linked immunosorbent assay. IRAP at concentrations 0.01, 0.1, and 1 microgram/ml decreased the allergen-stimulated IgE synthesis by 33 +/- 7%, 50 +/- 7%, and 66 +/- 5%, respectively (P < 0.05). Increasing the concentration of allergen did not affect the reduction in IgE synthesis observed in the presence of IRAP. Lipopolysaccharide-stimulated IgE synthesis was also significantly inhibited by IRAP (P < 0.05). In parallel experiments, anti-IL-1 beta monoclonal antibody showed a comparable inhibitory pattern on IgE synthesis (P < 0.05). IRAP inhibited the synthesis of interleukin-6, tumor necrosis factor-alpha, and granulocyte/macrophage colony-stimulating factor in a dose-dependent manner (P < 0.05); the mean inhibition was 31 +/- 4%, 75 +/- 5%, and 88 +/- 2%, respectively, at 1 microgram/ml of IRAP.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1994 Oct
PMID:Interleukin-1 receptor antagonist protein inhibits the synthesis of IgE and proinflammatory cytokines by allergen-stimulated mononuclear cells. 791 15

Gonadotropin regulation of granulosa cell (GC) differentiation can be modulated by non-steroidal factors, including cytokines. Interleukin-6 (IL-6), a broad spectrum cytokine, has been previously demonstrated to be produced by GCs and to directly influence follicle stimulating hormone (FSH) differentiated functions of ovarian GCs. In the present study, primary cultures of GCs were prepared from prepubertal sow ovaries. No significant amount of biological active IL-6 was detected in these cultures using the B9 cell growth bioassay. Although our findings suggest that GCs are not source of IL-6 in the porcine ovary, this cytokine may be released by leukocytes present in the ovary and modulate ovarian functions by acting on GCs. Here, adding recombinant human (rh)IL-6 to GC cultures inhibited differentiated functions induced by FSH such as aromatase activity, LH receptor (LHr) expression measured by specific 125I-hCG binding and progesterone (P) production. On the opposite, rhIL-6 did not modulate stimulatory human chorionic hormone (hCG) effects on P release by GCs and did not prevent hCG binding to LHr. These preliminary results clearly showed that IL-6 acted differently on FSH and hCG induced functions although these gonadotropins act primarily through the same transduction pathway involving generation of cyclic AMP. We suggest that IL-6 might act more likely by reducing FSH binding capacity than by modulating transduction pathways. Inhibitory IL-6 effects on FSH-induced functions were not neutralized by adding to culture media a monoclonal antibody against the human IL-6 signal transducer gp130, previously reported to inhibit IL-6 mediated effects in human cell lines.
Cell Mol Biol (Noisy-le-grand) 1994 May
PMID:Comparative IL-6 effects on FSH and hCG-induced functions in porcine granulosa cell cultures. 792 Jan 81

Interleukin-6 (IL-6) is a pleiotropic cytokine having several functions, including the regulation of immunologic and inflammatory responses. It is produced by many cell types, including lymphocytes, macrophages, and fibroblasts, and is believed to play a major role in pulmonary fibrosis, a condition resulting from expansion of the fibroblast compartment and the accumulation of extracellular matrices secreted primarily by fibroblasts. Production of IL-6 by lung fibroblasts has been well documented; however, it was not known whether all murine lung fibroblasts secreted IL-6 or only subsets thereof. Previous studies in our laboratory have shown that murine lung fibroblasts can be divided into subpopulations based on Thy 1 expression. These subpopulations, Thy 1+ and Thy 1-, differ in morphology, expression of surface markers, and function. IL-6 mRNA was detected in both Thy 1+ and Thy 1- murine fibroblasts and clones using reverse transcriptase polymerase chain reaction (RT-PCR). Interestingly, semi-quantitative RT-PCR and Northern blot analysis demonstrated that IL-6 mRNA was down-regulated in confluent fibroblast cultures versus cultures in log phase growth. Also, IL-6 activity was detected in the supernatants of murine lung fibroblast lines and clones using an IL-6-dependent hybridoma assay. Hybridoma proliferation was inhibited by the addition of a neutralizing anti-mouse IL-6 antibody, indicating that the activity was indeed due to IL-6. The lung fibroblasts expressed IL-6 receptors on their surface as determined by flow cytometry using a rat anti-mouse IL-6 receptor antibody (15A7).(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1994 Nov
PMID:Interleukin-6 is an autocrine growth factor for murine lung fibroblast subsets. 794 84

Mice of the C57BL/6 strain were injected with bacterial lipopolysaccharide (LPS) followed by formylnorleucyl-leucyl-phenylalanine (FNLP) by the intraperitoneal route; markers of acute lung injury were examined in mice given a fusion protein of soluble human tumor necrosis factor-alpha (TNF-alpha) receptor (p80) linked to the Fc portion of human IgG (TNFR:Fc) or excipient. Challenge with LPS/FNLP elicited an adult respiratory distress syndrome-like pathology characterized by sharp increases in levels of lactate dehydrogenase (LDH) and total proteins in bronchoalveolar lavage as well as in lung myeloperoxidase (MPO) content at 16 and 20 h after challenge. Infusion of 1 mg of TNFR:Fc 2 h before challenge very significantly abrogated the increases in LDH, protein levels, and MPO. Histologic analysis revealed that LPS/FNLP infusion resulted in an intravascular neutrophil agglomerate and perivascular/peribronchial damage; the extent of tissue lesions was significantly reduced, but not abrogated, by TNF-alpha depletion. There were moderate levels of antigenic TNF-alpha in lung homogenates at 16 and 20 h after challenge, not affected by infusion with TNFR:Fc. No bioactive TNF-alpha was detected in lung homogenates of challenged mice given TNFR:Fc. High levels of antigenic interleukin-6 (IL-6) were found in lung homogenates of challenged mice treated with TNFR:Fc or with diluent. Elevated levels of antigenic IL-6 and TNF-alpha were found in sera of challenged mice at 16 and 20 h after injection; TNFR:Fc-treated mice had a higher level of antigenic TNF-alpha than did challenged mice given diluent, but it was not bioactive.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1994 Jun
PMID:A mouse model of lung injury induced by microbial products: implication of tumor necrosis factor. 800 42

Induction of interleukin-6 (IL-6) gene expression is mediated by numerous agents involving all major signal transduction pathways. We have compared the effects of prostaglandins and their second messenger cyclic AMP (cAMP) with the effect of lipopolysaccharide (LPS) on IL-6 gene expression. We demonstrate that secretion of IL-6 is induced by cAMP in murine monocytic PU5-1.8 cells, even though to a lesser extent than by LPS. Nevertheless, cAMP and prostaglandins of the E series in the presence of theophylline induce transcription of the IL-6 promoter more strongly than LPS, suggesting distinctive effects of cAMP and LPS on posttranscriptional events. Mutations within four regulatory elements, namely, the multiple response element (MRE), AP-1, NF-IL6, and NF-kappa B sites, significantly reduce, but do not completely abrogate, inducibility by cAMP and prostaglandin E1, whereas alterations of four additional sites have no effects. LPS-induced promoter activity, however, is almost completely abolished by mutations in the NF-kappa B site, suggesting that a single regulatory element is crucial for inducibility by LPS. Stimulation by cAMP is correlated with the binding of inducible factors to the AP-1, NF-IL6, and NF-kappa B elements, whereas factors binding to the MRE are constitutively expressed. Recombinant cAMP response element-binding protein binds to the MRE, indicating a potential role for this factor in the cAMP response. Our results suggest that cAMP and prostaglandins act through multiple, partially redundant regulatory elements to induce IL-6 expression in monocytic cells. Nuclear events that overlap partially with the LPS response but also exhibit distinctive features are involved.
Mol Cell Biol 1994 Jul
PMID:Multiple regulatory elements in the interleukin-6 gene mediate induction by prostaglandins, cyclic AMP, and lipopolysaccharide. 800 51

Clusterin is an authentic Sertoli cell secretory product initially identified in the ram and rat testis. Subsequent studies have shown that this protein is present in almost all organs and in multiple species. Its mRNA increases in the brain undergoing degeneration as a result of infection, brain injury, and other pathological conditions such as Alzheimer's disease. However, its site(s) of synthesis and modulator(s) in the brain are not known. The objectives of this study were to determine if astrocytes could synthesize and secrete clusterin in vitro and to investigate the effects of various cytokines on the secretion and the mRNA expression of clusterin in the primary cultures of astrocytes. Astrocytes were isolated from cerebral cortices of neonatal rats and enriched to a purity of greater than 95% as judged by immunocytochemical staining using antibody against glial fibrillary acidic protein (GFAP), a specific marker of astrocytes. Using immunoprecipitation techniques, we have demonstrated that astrocytes actively synthesize and secrete clusterin in vitro. Immunocytochemical staining using a monospecific antibody against clusterin showed that this protein is localized in the entire cytoplasm and the processes of astrocytes. Treatment of astrocytes with either interleukin-1 beta, or interleukin-2, induced a significant increase in the production and the mRNA levels of clusterin, whereas other cytokines including interleukin-3, interleukin-6, and interferon-gamma had no apparent effect. The results of this study suggest that clusterin may be a marker to study the immune response in the brain.
Mol Cell Neurosci 1994 Jun
PMID:Regulation of clusterin secretion and mRNA expression in astrocytes by cytokines. 808 21


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