scholarly journals Biphasic increase in c-jun mRNA is required for induction of AP-1-mediated gene transcription: differential effects of muscarinic and thrombin receptor activation.

1992 ◽  
Vol 12 (10) ◽  
pp. 4742-4750 ◽  
Author(s):  
J Trejo ◽  
J C Chambard ◽  
M Karin ◽  
J H Brown
Keyword(s):  
Dna Binding ◽  
Gene Transcription ◽  
Time Course ◽  
Firefly Luciferase ◽  
Receptor Activation ◽  
Binding Activity ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Firefly Luciferase Gene ◽  
The Difference

Activation of either muscarinic cholinergic or thrombin receptors increases phosphoinositide turnover, Ca2+ mobilization, and redistribution of protein kinase C and induces rapid transient increases in c-fos mRNA and c-jun mRNA in 1321N1 cells. To determine whether the increases in c-fos and c-jun mRNA induced by carbachol and thrombin are sufficient to stimulate AP-1-mediated transactivation, 1321N1 cells were transfected with a reporter carrying two copies of the tetradecanoyl phorbol acetate response element and the firefly luciferase gene. Thrombin was significantly more effective than carbachol at stimulating AP-1-mediated transactivation. To identify the factors underlying the difference in AP-1 activity induced by carbachol and thrombin, members of the fos and jun families which encode components of AP-1 were examined. Carbachol and thrombin have similar effects on expression of c-fos, fosB, fra-2, junB, and junD, both acutely and over a 24-h time course. However, whereas carbachol leads only to transient induction of c-jun (maximal at 0.5 h), thrombin induces a biphasic increase in c-jun mRNA--an initial peak at 0.5 h and a second, more-prolonged increase at 12 h. Thrombin but not carbachol also induces a late increase in fra-1 mRNA, which peaks at 12 h. The secondary increase in c-jun mRNA is associated with marked increases in c-Jun protein levels and AP-1 DNA-binding activity. The late induction of c-jun and fra-1 mRNA can be prevented by adding the antagonist hirudin 30 min after thrombin, which results in loss of thrombin-stimulated increases in c-Jun protein, AP-1 DNA-binding activity, and AP-1-mediated transactivation. These findings suggest that rapid and transient conduction of c-fos and c-jun mRNA is insufficient to induce prominent changes in gene transcription, while the sustained increase in c-jun mRNA and perhaps the late induction of fra-1 mRNA are required for generation of AP-1 DNA-binding activity and transactivation through AP-1.

Biphasic increase in c-jun mRNA is required for induction of AP-1-mediated gene transcription: differential effects of muscarinic and thrombin receptor activation

1992 ◽  
Vol 12 (10) ◽  
pp. 4742-4750
Author(s):  
J Trejo ◽  
J C Chambard ◽  
M Karin ◽  
J H Brown
Keyword(s):  
Dna Binding ◽  
Gene Transcription ◽  
Time Course ◽  
Firefly Luciferase ◽  
Receptor Activation ◽  
Binding Activity ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Firefly Luciferase Gene ◽  
The Difference

Activation of either muscarinic cholinergic or thrombin receptors increases phosphoinositide turnover, Ca2+ mobilization, and redistribution of protein kinase C and induces rapid transient increases in c-fos mRNA and c-jun mRNA in 1321N1 cells. To determine whether the increases in c-fos and c-jun mRNA induced by carbachol and thrombin are sufficient to stimulate AP-1-mediated transactivation, 1321N1 cells were transfected with a reporter carrying two copies of the tetradecanoyl phorbol acetate response element and the firefly luciferase gene. Thrombin was significantly more effective than carbachol at stimulating AP-1-mediated transactivation. To identify the factors underlying the difference in AP-1 activity induced by carbachol and thrombin, members of the fos and jun families which encode components of AP-1 were examined. Carbachol and thrombin have similar effects on expression of c-fos, fosB, fra-2, junB, and junD, both acutely and over a 24-h time course. However, whereas carbachol leads only to transient induction of c-jun (maximal at 0.5 h), thrombin induces a biphasic increase in c-jun mRNA--an initial peak at 0.5 h and a second, more-prolonged increase at 12 h. Thrombin but not carbachol also induces a late increase in fra-1 mRNA, which peaks at 12 h. The secondary increase in c-jun mRNA is associated with marked increases in c-Jun protein levels and AP-1 DNA-binding activity. The late induction of c-jun and fra-1 mRNA can be prevented by adding the antagonist hirudin 30 min after thrombin, which results in loss of thrombin-stimulated increases in c-Jun protein, AP-1 DNA-binding activity, and AP-1-mediated transactivation. These findings suggest that rapid and transient conduction of c-fos and c-jun mRNA is insufficient to induce prominent changes in gene transcription, while the sustained increase in c-jun mRNA and perhaps the late induction of fra-1 mRNA are required for generation of AP-1 DNA-binding activity and transactivation through AP-1.

Constitutive activation of STAT-3 and downregulation of SOCS-3 expression induced by adrenalectomy

2001 ◽  
Vol 281 (6) ◽  
pp. R2048-R2058 ◽  
Author(s):  
Abram M. Madiehe ◽  
Ling Lin ◽  
Christy White ◽  
H. Doug Braymer ◽  
George A. Bray ◽  
...  
Keyword(s):  
Dna Binding ◽  
Signaling Pathway ◽  
Leptin Receptor ◽  
Binding Activity ◽  
Janus Kinase ◽  
Adrenal Steroids ◽  
Western Blots ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Stat Signaling

Removal of adrenal steroids by adrenalectomy (ADX) slows or reverses the development of many forms of obesity in rodents, including those that are leptin or leptin receptor deficient. Obesity is associated with hyperleptinemia and leptin resistance. We hypothesized that glucocorticoids impair leptin receptor signaling and that removal thereof would activate the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) signaling pathway. The inhibitory effect of leptin (2.5 μg icv) on food intake was enhanced in ADX rats. A combination of ribonuclease protection assays, RT-PCR, Western blots, and mobility shift assays was used to evaluate the leptin signaling pathway in whole hypothalami from sham-operated, ADX and corticosterone-replaced ADX (ADX-R) Sprague-Dawley rats that were treated acutely with either saline vehicle or leptin intracerebroventricularly. ADX increased the expression of leptin receptor mRNA, increased STAT-3 mRNA and protein levels, induced constitutive STAT-3 phosphorylation and DNA binding activity, and also reduced suppressor of cytokine signaling-3 (SOCS-3) mRNA and protein levels. ADX and leptin treatment increased STAT-3 phosphorylation, but with no concomitant increase in DNA binding activity. Leptin and ADX decreased NPY mRNA expression, but their combination did not further decrease NPY mRNA. Corticosterone supplementation of ADX rats partially reversed many of these effects. In conclusion, ADX through activation of STAT-3 and inhibition of SOCS-3 activates the JAK-STAT signaling pathway. These effects most probably explain the ability to prevent the development of obesity by removal of adrenal steroids.

Transformation by Fos proteins requires a C-terminal transactivation domain

1993 ◽  
Vol 13 (12) ◽  
pp. 7429-7438
Author(s):  
R Wisdon ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Leucine Zipper ◽  
Fibroblast Cell ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Transactivation Domain ◽  
Functional Requirements ◽  
Dna Binding Activity ◽  
The Difference ◽  
Transforming Proteins

The Fos family of proteins now includes seven members: the retroviral proteins FBR-v-Fos and FBJ-v-Fos and the cellular proteins c-Fos, FosB, FosB2, Fra1, and Fra2. Four proteins (FBR-v-Fos, FBJ-v-Fos, c-Fos, and FosB) transform established rodent fibroblast cell lines, while three (FosB2, Fra1, and Fra2) do not. As all family members display sequence-specific DNA-binding activity as part of a heterodimeric complex with Jun proteins, other features must account for the differences in transforming potential. We demonstrate here that all transforming members have a C-terminal transactivation domain that is lacking in nontransforming members. The nontransforming proteins Fra1 and Fra2 can be converted to transforming proteins by fusion of a transactivation domain from either FosB or VP16. We also demonstrate that differences in the basic region-leucine zipper domain affecting either the affinity or sequence specificity of DNA binding are not determinants of the difference in transforming potential among members of the Fos family. The results further define the functional requirements for transformation by Fos proteins and suggest that the subunit composition of AP1 complexes is an important determinant of mitogenic signalling capability.

scholarly journals α-MSH inhibits induction of C/EBPβ-DNA binding activity and NOS2 gene transcription in macrophages

2000 ◽  
Vol 57 (6) ◽  
pp. 2239-2248 ◽  
Author(s):  
Ashish K. Gupta ◽  
Rebecca A. Diaz ◽  
Sandra Higham ◽  
Bruce C. Kone
Keyword(s):  
Dna Binding ◽  
Gene Transcription ◽  
Binding Activity ◽  
Dna Binding Activity

scholarly journals Hyaluronan fragments activate an NF-kappa B/I-kappa B alpha autoregulatory loop in murine macrophages.

1996 ◽  
Vol 183 (5) ◽  
pp. 2373-2378 ◽  
Author(s):  
P W Noble ◽  
C M McKee ◽  
M Cowman ◽  
H S Shin
Keyword(s):  
Molecular Weight ◽  
Dna Binding ◽  
Inflammatory Response ◽  
Time Course ◽  
Inflammatory Responses ◽  
Binding Activity ◽  
Nf Kappa B ◽  
Murine Macrophages ◽  
I Kappa B Alpha ◽  
Dna Binding Activity

Macrophages play an important role in the acute tissue inflammatory response through the release of cytokines and growth factors in response to stimuli such as lipopolysaccharide (LPS). Macrophage inflammatory effector functions are also influenced by interactions with the extracellular matrix (ECM). Such macrophage-ECM interactions may be important in regulating chronic inflammatory responses. Recent evidence has suggested that hyaluronan (HA), a glycosaminoglycan (GAG) component of ECM can induce inflammatory gene expression in murine macrophages. HA exists in its native form as a large polymer, but is found as smaller fragments under inflammatory conditions. The NF-kappa B/I-kappa B transcriptional regulatory system has been shown to be a critical component of the host inflammatory response. We examined the effects of high molecular weight HA and lower molecular weight HA fragments on NF-kappa B activation in mouse macrophages. Only the smaller HA fragments were found to activate NF-kappa B DNA binding activity. After HA stimulation, I-kappa B alpha mRNA was induced and I-kappa B alpha protein levels, which initially decreased, were restored. The induction of I-kappa Balpha expression was not observed for other GAGs. The time course of I-kappa B alpha protein regeneration in response to HA fragments was consistent with an autoregulatory mechanism. In support of this mechanism, in vitro translated murine I-kappa B alpha inhibited HA fragment-induced NF-kappa B DNA binding activity. The NF-kappa B DNA binding complex in HA-stimulated extracts was found to contain p50 and p65 subunits. Activation of the NF-kappa B/I-kappa B system in macrophages by ECM fragments may be an important mechanism for propagating the tissue inflammatory response.

scholarly journals Transformation by Fos proteins requires a C-terminal transactivation domain.

1993 ◽  
Vol 13 (12) ◽  
pp. 7429-7438 ◽  
Author(s):  
R Wisdon ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Leucine Zipper ◽  
Fibroblast Cell ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Transactivation Domain ◽  
Functional Requirements ◽  
Dna Binding Activity ◽  
The Difference ◽  
Transforming Proteins

The Fos family of proteins now includes seven members: the retroviral proteins FBR-v-Fos and FBJ-v-Fos and the cellular proteins c-Fos, FosB, FosB2, Fra1, and Fra2. Four proteins (FBR-v-Fos, FBJ-v-Fos, c-Fos, and FosB) transform established rodent fibroblast cell lines, while three (FosB2, Fra1, and Fra2) do not. As all family members display sequence-specific DNA-binding activity as part of a heterodimeric complex with Jun proteins, other features must account for the differences in transforming potential. We demonstrate here that all transforming members have a C-terminal transactivation domain that is lacking in nontransforming members. The nontransforming proteins Fra1 and Fra2 can be converted to transforming proteins by fusion of a transactivation domain from either FosB or VP16. We also demonstrate that differences in the basic region-leucine zipper domain affecting either the affinity or sequence specificity of DNA binding are not determinants of the difference in transforming potential among members of the Fos family. The results further define the functional requirements for transformation by Fos proteins and suggest that the subunit composition of AP1 complexes is an important determinant of mitogenic signalling capability.

Estradiol upregulates mesangial cell MMP-2 activity via the transcription factor AP-2

2002 ◽  
Vol 282 (1) ◽  
pp. F164-F169 ◽  
Author(s):  
Michael Guccione ◽  
Sharon Silbiger ◽  
Jun Lei ◽  
Joel Neugarten
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Protein Expression ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Binding Activity ◽  
Dependent Manner ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Metalloproteinase Activity

The accumulation of extracellular matrix in the glomerular mesangium reflects the net balance between the synthesis and degradation of matrix components. We have shown that estradiol suppresses the synthesis of types I and IV collagen by cultured mesangial cells (Kwan G, Neugarten J, Sherman M, Ding Q, Fotadar U, Lei J, and Silbiger S. Kidney Int 50: 1173–1179, 1996; Neugarten J, Acharya A, Lei J, and Silbiger S. Am J Physiol Renal Physiol 279: F309–F318, 2000; Neugarten J, Medve I, Lei J, and Silbiger SR. Am J Physiol Renal Physiol 277: F1–F8, 1999; Neugarten J and Silbiger S. Am J Kidney Dis 26: 147–151, 1995; Silbiger S, Lei J, and Neugarten J. Kidney Int 55: 1268–1276, 1998; Silbiger S, Lei J, Ziyadeh FN, and Neugarten J. Am J Physiol Renal Physiol 274: F1113–F1118, 1998). In the present study, we evaluated the effects of sex hormones on the activity of matrix metalloproteinase-2 (MMP-2) in murine mesangial cells, the synthesis of which is regulated by the transcription factor activator protein-2 (AP-2). Estradiol stimulated MMP-2 activity by increasing MMP-2 protein levels in a dose-dependent manner. These effects occurred at physiological concentrations of estradiol and were receptor mediated. Estradiol also increased AP-2 protein levels and increased binding of mesangial cell nuclear extracts to an AP-2 consensus binding sequence oligonucleotide. The ability of estradiol to increase AP-2 protein expression, AP-2/DNA binding activity, MMP-2 protein expression, and metalloproteinase activity was reversed by PD-98059, a selective inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signaling cascade. We conclude that estradiol upregulates the MAPK cascade, which in turn stimulates the synthesis of AP-2 protein. The resultant increased AP-2/DNA binding activity leads to increased synthesis of MMP-2 and increased metalloproteinase activity. Stimulation of metalloproteinase activity by estradiol may contribute to the protective effect of female gender on renal disease progression.

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