Regulation and role of suppressor of cytokine signaling-3 in hypothalamic 4B cells

Corticotropin-releasing factor (CRF) plays a central role in regulating stress responses. In the hypothalamic paraventricular nucleus (PVN), CRF, produced in response to stress, stimulates the release of ACTH from the anterior pituitary. ACTH then stimulates the release of glucocorticoids from the adrenal glands; circulating glucocorticoids are critical for recovery from stress conditions. Cytokines are also implicated in the regulation of CRF expression. Among them, interleukin (IL)-6 plays a role in the regulation of CRF. Factors other than glucocorticoids are likely to be involved in limiting the stimulation of CRF during stress. Suppressor of cytokine signaling (SOCS)-3 acts as a potent negative regulator of cytokine signaling. Little is known about the ability of the inhibitory signaling pathways to limit activation of the CRF gene in parvocellular PVN neurons. Hypothalamic 4B cells are useful for exploring the mechanisms, because these cells show characteristics of the parvocellular neurons of the PVN. In the present study, we examined whether SOCS-3 is regulated by IL-6 and cAMP in hypothalamic 4B cells. We also explored the involvement of SOCS-3 in the regulation of CRF gene expression. SOCS-3 was found to be regulated by IL-6 and via the cAMP/protein kinase A pathway in the hypothalamic cells. SOCS-3 knockdown increased IL-6- or forskolin-induced CRF gene transcription and mRNA levels. Therefore, SOCS-3, induced by a cAMP stimulant and IL-6, would be involved in the negative regulation of CRF gene expression in hypothalamic cells.

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Leptin inhibits hypothalamic Npy and Agrp gene expression via a mechanism that requires phosphatidylinositol 3-OH-kinase signaling

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00094.2005 ◽

2005 ◽

Vol 289 (6) ◽

pp. E1051-E1057 ◽

Cited By ~ 140

Author(s):

Christopher D. Morrison ◽

Gregory J. Morton ◽

Kevin D. Niswender ◽

Richard W. Gelling ◽

Michael W. Schwartz

Keyword(s):

Gene Expression ◽

Inhibitory Effect ◽

Cytokine Signaling ◽

Pi3k Signaling ◽

Mrna Levels ◽

Sprague Dawley ◽

Suppressor Of Cytokine Signaling ◽

Stat3 Signaling ◽

Sprague Dawley Rats ◽

Phosphatidylinositol 3

Phosphatidylinositol 3-OH-kinase (PI3K) and STAT3 are signal transduction molecules activated by leptin in brain areas controlling food intake. To investigate their role in leptin-mediated inhibition of hypothalamic neuropeptide Y ( Npy) and agouti-related peptide ( Agrp) gene expression, male Sprague-Dawley rats ( n = 5/group) were either fed ad libitum or subjected to a 52-h fast. At 12-h intervals, the PI3K inhibitor LY-294002 (LY, 1 nmol) or vehicle was injected intracerebroventricularly (ICV) as a pretreatment, followed 1 h later by leptin (3 μg icv) or vehicle. Fasting increased hypothalamic Npy and Agrp mRNA levels ( P < 0.05), and ICV leptin administration prevented this increase. As predicted, LY pretreatment blocked this inhibitory effect of leptin, such that Npy and Agrp levels in LY-leptin-treated animals were similar to fasted controls. By comparison, leptin-mediated activation of hypothalamic STAT3 signaling, as measured by induction of both phospho-STAT3 immunohistochemistry and suppressor of cytokine signaling-3 ( Socs3) mRNA, was not significantly attenuated by ICV LY pretreatment. Because NPY/AgRP neurons project to the hypothalamic paraventricular nucleus (PVN), we next investigated whether leptin activation of PVN neurons is similarly PI3K dependent. Compared with vehicle, leptin increased the number of c-Fos positive cells within the parvocellular PVN ( P = 0.001), and LY pretreatment attenuated this effect by 35% ( P = 0.043). We conclude that leptin requires intact PI3K signaling both to inhibit hypothalamic Npy and Agrp gene expression and activate neurons within the PVN. In addition, these data suggest that leptin activation of STAT3 is insufficient to inhibit expression of Npy or Agrp in the absence of PI3K signaling.

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The Arabidopsis mediator complex subunit 8 regulates oxidative stress responses

The Plant Cell ◽

10.1093/plcell/koab079 ◽

2021 ◽

Cited By ~ 1

Author(s):

Huaming He ◽

Jordi Denecker ◽

Katrien Van Der Kelen ◽

Patrick Willems ◽

Robin Pottie ◽

...

Keyword(s):

Oxidative Stress ◽

Gene Expression ◽

Salicylic Acid ◽

Jasmonic Acid ◽

Stress Responses ◽

Negative Regulator ◽

Mediator Complex ◽

Defense Gene Expression ◽

A Genome ◽

Oxidative Stress Responses

Abstract Signaling events triggered by hydrogen peroxide (H2O2) regulate plant growth and defense by orchestrating a genome-wide transcriptional reprogramming. However, the specific mechanisms that govern H2O2-dependent gene expression are still poorly understood. Here, we identify the Arabidopsis Mediator complex subunit MED8 as a regulator of H2O2 responses. The introduction of the med8 mutation in a constitutive oxidative stress genetic background (catalase-deficient, cat2) was associated with enhanced activation of the salicylic acid pathway and accelerated cell death. Interestingly, med8 seedlings were more tolerant to oxidative stress generated by the herbicide methyl viologen (MV) and exhibited transcriptional hyperactivation of defense signaling, in particular salicylic acid- and jasmonic acid-related pathways. The med8-triggered tolerance to MV was manipulated by the introduction of secondary mutations in salicylic acid and jasmonic acid pathways. In addition, analysis of the Mediator interactome revealed interactions with components involved in mRNA processing and microRNA biogenesis, hence expanding the role of Mediator beyond transcription. Notably, MED8 interacted with the transcriptional regulator NEGATIVE ON TATA-LESS, NOT2, to control the expression of H2O2-inducible genes and stress responses. Our work establishes MED8 as a component regulating oxidative stress responses and demonstrates that it acts as a negative regulator of H2O2-driven activation of defense gene expression.

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Heat Shock Protein 60 Activates Cytokine-Associated Negative Regulator Suppressor of Cytokine Signaling 3 in T Cells: Effects on Signaling, Chemotaxis, and Inflammation

The Journal of Immunology ◽

10.4049/jimmunol.175.1.276 ◽

2005 ◽

Vol 175 (1) ◽

pp. 276-285 ◽

Cited By ~ 52

Author(s):

Alexandra Zanin-Zhorov ◽

Guy Tal ◽

Shoham Shivtiel ◽

Michal Cohen ◽

Tsvee Lapidot ◽

...

Keyword(s):

T Cells ◽

Heat Shock ◽

Heat Shock Protein ◽

Negative Regulator ◽

Cytokine Signaling ◽

Heat Shock Protein 60 ◽

Suppressor Of Cytokine Signaling

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Endothelin-1 stimulates suppressor of cytokine signaling-3 gene expression in adipocytes

General and Comparative Endocrinology ◽

10.1016/j.ygcen.2012.06.024 ◽

2012 ◽

Vol 178 (3) ◽

pp. 450-458 ◽

Cited By ~ 9

Author(s):

Hsin-Huei Chang ◽

Yao-Ming Huang ◽

Chi-Peng Wu ◽

Ya-Chu Tang ◽

Chi-Wei Liu ◽

...

Keyword(s):

Gene Expression ◽

Cytokine Signaling ◽

Suppressor Of Cytokine Signaling ◽

Endothelin 1

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Potentially probiotic bacteria induce cytokine production and suppressor of cytokine signaling 3 gene expression in human monocyte-derived macrophages

Cytokine ◽

10.1016/j.cyto.2009.07.423 ◽

2009 ◽

Vol 48 (1-2) ◽

pp. 100-101 ◽

Cited By ~ 1

Author(s):

Sinikka Latvala ◽

Minja Miettinen ◽

Riina Kekkonen ◽

Riitta Korpela ◽

Ilkka Julkunen

Keyword(s):

Gene Expression ◽

Cytokine Production ◽

Human Monocyte ◽

Probiotic Bacteria ◽

Cytokine Signaling ◽

Suppressor Of Cytokine Signaling

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The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3

Blood ◽

10.1182/blood-2006-08-039735 ◽

2007 ◽

Vol 109 (11) ◽

pp. 4924-4929 ◽

Cited By ~ 86

Author(s):

Michelle B. Hookham ◽

Joanne Elliott ◽

Yvonne Suessmuth ◽

Judith Staerk ◽

Alister C. Ward ◽

...

Keyword(s):

Tyrosine Phosphorylation ◽

Mononuclear Cells ◽

Jak2 V617f ◽

Myeloproliferative Disorders ◽

Negative Regulator ◽

Cytokine Signaling ◽

Suppressor Of Cytokine Signaling ◽

Peripheral Blood Mononuclear ◽

Socs3 Protein ◽

Mutant Kinase

Abstract The somatic JAK2 valine-to-phenylalanine (V617F) mutation has been detected in up to 90% of patients with polycythemia and in a sizeable proportion of patients with other myeloproliferative disorders such as essential thrombocythemia and idiopathic myelofibrosis. Suppressor of cytokine signaling 3 (SOCS3) is known to be a strong negative regulator of erythropoietin (EPO) signaling through interaction with both the EPO receptor (EPOR) and JAK2. We report here that JAK2 V617F cannot be regulated and that its activation is actually potentiated in the presence of SOCS3. Instead of acting as a suppressor, SOCS3 enhanced the proliferation of cells expressing both JAK2 V617F and EPOR. Additionally, although SOCS1 and SOCS2 are degraded in the presence of JAK2 V617F, turnover of SOCS3 is inhibited by the JAK2 mutant kinase and this correlated with marked tyrosine phosphorylation of SOCS3 protein. We also observed constitutive tyrosine phosphorylation of SOCS3 in peripheral blood mononuclear cells (PBMCs) derived from patients homozygous for the JAK2 V617F mutant. These findings suggest that the JAK2 V617F has overcome normal SOCS regulation by hyperphosphorylating SOCS3, rendering it unable to inhibit the mutant kinase. Thus, JAK2 V617F may even exploit SOCS3 to potentiate its myeloproliferative capacity.

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Synergistic Up-Regulation of Heme Oxygenase-1 in Human Liver by Heme and siRNA to Bach1:Possible Therapeutic Implications.

Blood ◽

10.1182/blood.v104.11.1633.1633 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1633-1633

Author(s):

Tahereh Ghaziani ◽

Ying Shan ◽

Richard W. Lambrecht ◽

Herbert L. Bonkovsky

Keyword(s):

Gene Expression ◽

Heme Oxygenase ◽

Ischemia Reperfusion Injury ◽

Tissue Injury ◽

Ischemia Reperfusion ◽

Negative Regulator ◽

Heme Oxygenase 1 ◽

Significant Finding ◽

Mrna Levels ◽

Protein Levels

Abstract Background: Heme oxygenase-1 (HO-1) is an antioxidant defense enzyme that converts toxic heme into antioxidants. HO-1 is strongly up-regulated by its physiologic substrate, heme, which is currently the treatment of choice for acute attacks of porphyria and which may have other therapeutic uses, as well (e.g., for cytoprotection or amelioration of ischemia/reperfusion injury by increasing supply of carbon monoxide, biliverdin, or bilirubin). Up-regulation of HO-1 expression has been associated with increased resistance to tissue injury. Bach1 is a bZip protein which forms heterodimers with small Maf proteins. HO-1 is expressed at higher levels in tissues of Bach1-deficient mice, indicating that Bach1 acts as a negative regulator of the mouse HO-1 gene. The molecular mechanism that confers repression of HO-1 by Bach1, and whether there are similar effects in human cells, has remained elusive. The aim of this study was to assess whether modulation of human hepatic Bach1 expression by siRNA technology influences HO-1 gene expression and whether such gene silencing would enhance the inducing effects of heme on HO-1. Methods: siRNAs targeted 4 different positions of human Bach1 mRNA were designed and synthesized. We transfected Bach1-siRNA (25–200 nM) into Huh-7 cells using Lipofectamine for 24–72 h, after which, cells were treated with or without heme. We quantified HO-1 and Bach1 mRNA and protein levels by quantitative RT-PCR and western blotting, respectively. Effects and specificity of Bach1-siRNA were analyzed and compared with those of non-Bach1 related siRNAs (non-specific control-duplex (NSCD) and LaminB2-siRNA). Results: Bach1-siRNAs (25–200 nM) transfected into Huh-7 cells for 24–72 h significantly reduced Bach1 mRNA and protein levels approximately 80%, compared with non siRNA treated cells. In contrast, transfection with same amounts of NSCD or LaminB2 siRNA did not reduce Bach1 mRNA or protein levels, confirming the specificity of Bach1-siRNA in Huh-7 cells. A significant finding of these studies was the 7-fold up-regulation of the HO-1 gene in Bach1-siRNA transfected cells, compared to cells without Bach1-siRNA or those transfected with NSCD or LaminB2. Bach1, NSCD, and LaminB2 siRNAs had no effect on HO-2 or 5-aminolevulinate synthase-1 mRNA levels (two genes that are not induced by heme). The effects of increasing concentrations of heme (up to 10 μM) in the presence or absence of Bach1-siRNA on the levels of HO-1 mRNA expression are shown in the Figure. For all of the heme concentrations tested, the levels of HO-1 mRNA were greater when Bach1 siRNA was present. Conclusions: Bach1 has a specific and selective effect to repress expression of human hepatic HO-1. Silencing of the Bach1 gene by siRNAs may be a useful method for up-regulating HO-1 gene expression. The combination of intravenous heme and Bach1 silencing may be useful for therapy of acute porphyrias in relapse or other conditions in which up-regulation of HO-1 may be beneficial. (Supported by grants from NIH [DK38825] and Ovation Pharmaceuticals, Inc.) Figure Figure

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Suppressor of cytokine signaling 3 knockdown in the mediobasal hypothalamus: counterintuitive effects on energy balance

Journal of Molecular Endocrinology ◽

10.1677/jme-10-0057 ◽

2010 ◽

Vol 45 (5) ◽

pp. 341-353 ◽

Cited By ~ 11

Author(s):

M W A de Backer ◽

M A D Brans ◽

A J van Rozen ◽

E M van der Zwaal ◽

M C M Luijendijk ◽

...

Keyword(s):

Locomotor Activity ◽

Energy Balance ◽

Viral Vectors ◽

Body Weight Gain ◽

Cytokine Signaling ◽

Dark Phase ◽

Mrna Levels ◽

Mediobasal Hypothalamus ◽

Suppressor Of Cytokine Signaling ◽

Adult Rats

An increase in brain suppressor of cytokine signaling 3 (SOCS3) has been implicated in the development of both leptin and insulin resistance. Socs3 mRNA is localized throughout the brain, and it remains unclear which brain areas are involved in the effect of SOCS3 levels on energy balance. We investigated the role of SOCS3 expressed in the mediobasal hypothalamus (MBH) in the development of diet-induced obesity in adult rats. Socs3 mRNA was down-regulated by local injection of adeno-associated viral vectors expressing a short hairpin directed against Socs3, after which we determined the response to high-fat high-sucrose choice diet. In contrast to neuronal Socs3 knockout mice, rats with SOCS3 knockdown limited to the MBH showed increased body weight gain, larger amounts of white adipose tissue, and higher leptin concentrations at the end of the experiment. These effects were partly due to the decrease in locomotor activity, as 24 h food intake was comparable with controls. In addition, rats with Socs3 knockdown in the MBH showed alterations in their meal patterns: average meal size in the light period was increased and was accompanied by a compensatory decrease in meal frequency in the dark phase. In addition, neuropeptide Y (Npy) mRNA levels were significantly increased in the arcuate nucleus of Socs3 knockdown rats. Since leptin is known to stimulate Npy transcription in the absence of Socs3, these data suggest that knockdown of Socs3 mRNA limited to the MBH increases Npy mRNA levels, which subsequently decreases locomotor activity and alters feeding patterns.

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