Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytokines are secreted proteins that regulate important cellular responses such as proliferation and differentiation. Key events in cytokine signal transduction are well defined: cytokines induce receptor aggregation, leading to activation of members of the JAK family of cytoplasmic tyrosine kinases. In turn, members of the STAT family of transcription factors are phosphorylated, dimerize and increase the transcription of genes with STAT recognition sites in their promoters. Less is known of how cytokine signal transduction is switched off. We have cloned a complementary DNA encoding a protein SOCS-1, containing an SH2-domain, by its ability to inhibit the macrophage differentiation of M1 cells in response to interleukin-6. Expression of SOCS-1 inhibited both interleukin-6-induced receptor phosphorylation and STAT activation. We have also cloned two relatives of SOCS-1, named SOCS-2 and SOCS-3, which together with the previously described CIS form a new family of proteins. Transcription of all four SOCS genes is increased rapidly in response to interleukin-6, in vitro and in vivo, suggesting they may act in a classic negative feedback loop to regulate cytokine signal transduction.
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PMID:A family of cytokine-inducible inhibitors of signalling. 920 25

SOCS-1 (suppressor of cytokine signaling-1) is a representative of a family of negative regulators of cytokine signaling (SOCS-1 to SOCS-7 and CIS) characterized by a highly conserved C-terminal SOCS box preceded by an SH2 domain. This study comprehensively examined the ability of several SOCS family members to negatively regulate the gp130 signaling pathway. SOCS-1 and SOCS-3 inhibited both interleukin-6 (IL-6)- and leukemia inhibitory factor (LIF)-induced macrophage differentiation of murine monocytic leukemic M1 cells and LIF induction of a Stat3-responsive reporter construct in 293T fibroblasts. Deletion of amino acids 51-78 in the N-terminal region of SOCS-1 prevented inhibition of LIF signaling. The SOCS-1 and SOCS-3 N-terminal regions were functionally interchangeable, but this did not extend to other SOCS family members. Mutation of SH2 domains abrogated the ability of both SOCS-1 and SOCS-3 to inhibit LIF signal transduction. Unlike SOCS-1, SOCS-3 was unable to inhibit JAK kinase activity in vitro, suggesting that SOCS-1 and SOCS-3 act on the JAK-STAT pathway in different ways. Thus, although inhibition of signaling by SOCS-1 and SOCS-3 requires both the SH2 and N-terminal domains, their mechanisms of action appear to be biochemically different.
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PMID:Mutational analyses of the SOCS proteins suggest a dual domain requirement but distinct mechanisms for inhibition of LIF and IL-6 signal transduction. 988 94

SOCS-1 was originally identified as an inhibitor of interleukin-6 signal transduction and is a member of a family of proteins (SOCS-1 to SOCS-7 and CIS) that contain an SH2 domain and a conserved carboxyl-terminal SOCS box motif. Mutation studies have established that critical contributions from both the amino-terminal and SH2 domains are essential for SOCS-1 and SOCS-3 to inhibit cytokine signaling. Inhibition of cytokine-dependent activation of STAT3 occurred in cells expressing either SOCS-1 or SOCS-3, but unlike SOCS-1, SOCS-3 did not directly interact with or inhibit the activity of JAK kinases. Although the conserved SOCS box motif appeared to be dispensable for SOCS-1 and SOCS-3 action when overexpressed, this domain interacts with elongin proteins and may be important in regulating protein turnover. In gene knockout studies, SOCS-1(-/-) mice were born but failed to thrive and died within 3 weeks of age with fatty degeneration of the liver and hemopoietic infiltration of several organs. The thymus in SOCS-1(-/-) mice was small, the animals were lymphopenic, and deficiencies in B lymphocytes were evident within hemopoietic organs. We propose that the absence of SOCS-1 in these mice prevents lymphocytes and liver cells from appropriately controlling signals from cytokines with cytotoxic side effects.
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PMID:Suppressors of cytokine signaling (SOCS): negative regulators of signal transduction. 1053 14

CIS (cytokine-inducible SH2 protein), SOCS (suppressor of cytokine signaling), or SSI (signal transducers and activators of transcription [STAT]-induced STAT inhibitor) proteins are a family of cytokine-inducible negative regulators of cytokine signaling via Janus kinase (JAK)-STAT pathways. Given the evidence that the JAK-STAT pathway plays a critical role in the cardiovascular system, the primary objective of this study was to assess the effects of the CIS family on JAK-STAT signaling in the cardiovascular system in rats treated with cardiotrophin-1 (CT-1), an interleukin-6 family of cytokines. Intravenous injection of 20 microgram/kg body weight of CT-1 induced a transient, marked increase in STAT3 activation in various tissues, including heart and lung, and subsequent upregulation of 2 members of the CIS family, JAK-binding protein (JAB)/SOCS-1/SSI-1 and CIS3/SOCS-3/SSI-3, in the same tissues. It was also observed that CIS3 was directly associated with JAK2 in vivo. Pretreatment with the same dose of CT-1 60 minutes before significantly attenuated the STAT3 activation induced by a second injection of CT-1. We previously reported that intravenous injection of CT-1 results in the nitric oxide (NO)-dependent hypotension accompanied by the induction of inducible NO synthase mRNA. In rats pretreated with CT-1, the induction of inducible NO synthase mRNA or hypotension by subsequent CT-1 injection was not observed. Forced expression of JAB or CIS3, but not other CISs, directly blocked CT-1-induced STAT3 activation in 293 cells. These results suggest that JAB and CIS3 serve as endogenous inhibitors of CT-1-mediated JAK-STAT signaling in the cardiovascular system in vivo.
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PMID:Induction of JAB/SOCS-1/SSI-1 and CIS3/SOCS-3/SSI-3 is involved in gp130 resistance in cardiovascular system in rat treated with cardiotrophin-1 in vivo. 1130 96

In sera of cachectic patients bearing advanced cancers, the concentration of interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrotizing factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) have been reported to elevate. In this study, we investigated whether those cytokines influenced in vitro anti-tumor effect of 5-fluorouracil (5-FU) on a human colon tumor cell line, HCT-15. Pretreatment of HCT-15 cells with IL-1 beta, IL-6 or TNF-alpha did not affect the anti-tumor effect of 5-FU at various concentrations. However, IFN-gamma attenuated the anti-tumor effect of 5-FU at the concentrations of 0.1-10 IU/ml. An experiment with tritium thymidine showed that 0.1 IU/ml of IFN-gamma did not suppress the growth of HCT-15 cells. As low as 0.1 IU/ml of IFN-gamma attenuated the anti-tumor effect of 5-FU in another experimental system where HCT-15 cells were exposed to 0.1 IU/ml of IFN-gamma before and during the treatment with 5-FU. This system mimicked the clinical condition around in situ cancer cells. Treatment of HCT-15 cells with 0.1-10 IU/ml of IFN-gamma did not change their DNA histogram pattern. An immunoblotting with the antibodies to thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) in HCT-15 cells revealed that 0.1-10 IU/ml of IFN-gamma enhanced their TS and DPD expressions. Results of the immunoblotting gave some explanation to attenuation in the sensitivity of HCT-15 cells to 5-FU.
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PMID:Serum factors attenuating the anti-tumor activity of 5-fluorouracil. 1160 2

MUP/hIL-6 transgenic mice overexpressing human interleukin-6 (IL-6) are growth-retarded. As documented here, the major transcriptional factor constitutively activated by IL-6 in the MUP/hIL6 transgenic mice was signal transducer and transactivator 3 (STAT3). Since STAT3 has been implicated in the expression of negative regulators of GH signaling, the suppressors of cytokine signaling (SOCS) genes, we have in this study examined the expression of SOCS1, SOCS2, SOCS3, and CIS genes. We found a large, 5-fold increase in SOCS3 mRNA in the liver, brain, skeletal muscle, and the lung of the MUP/hIL-6 transgenic mice. SOCS genes are thought to inhibit activation of transcriptional factor STAT5 by GH. Despite the induction of SOCS3 mRNA, STAT5 was activated in growth-retarded transgenic mice in response to elevated endogenous GH serum levels. The significance of activation of STAT3 and STAT5 transcription factors for cell proliferation and growth impairment in this mouse model is therefore discussed.
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PMID:Growth impairment in IL-6-overexpressing transgenic mice is associated with induction of SOCS3 mRNA. 1255 79

Deoxynivalenol (DON), a trichothecene mycotoxin found in grains and cereal-based foods worldwide, impairs weight gain in experimental animals but the underlying mechanisms remain undetermined. Oral exposure to DON induces rapid and transient upregulation of proinflammatory cytokine expression in the mouse. The latter are known to induce several suppressors of cytokine signaling (SOCS), some of which impair growth hormone (GH) signaling. We hypothesized that oral exposure to DON will induce SOCS expression in the mouse. Real-time PCR and cytokine bead array revealed that oral gavage with DON rapidly (1 h) induced tumor necrosis factor-alpha and interleukin-6 mRNA and protein expression in several organs and plasma, respectively. Upregulation of mRNAs for four well-characterized SOCS (CIS [cytokine-inducible SH2 domain protein], SOCS1, SOCS2, and SOCS3) was either concurrent with (1 h) or subsequent to cytokine upregulation (2 h). Notably, DON-induced SOCS3 mRNAs in muscle, spleen and liver, with CIS1, SOCS1, and SOCS2 occurring to a lesser extent. Hepatic SOCS3 mRNA was a very sensitive indicator of DON exposure with SOCS3 protein being detectable in the liver well after the onset of cytokine decline (5 h). Furthermore, hepatic SOCS upregulation was associated with about 75% suppression of GH-inducible insulin-like growth factor acid labile subunit. Taken together, DON-induced cytokine upregulation corresponded to increased expression of several SOCS, and was associated with suppression of GH-inducible gene expression in the liver.
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PMID:Induction of suppressors of cytokine signaling by the trichothecene deoxynivalenol in the mouse. 1993 2