Creatine feeding increases GLUT4 expression in rat skeletal muscle

2005 ◽  
Vol 288 (2) ◽  
pp. E347-E352 ◽  
Author(s):  
Jeong-Sun Ju ◽  
Jill L. Smith ◽  
Peter J. Oppelt ◽  
Jonathan S. Fisher
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Dna Binding ◽  
Binding Activity ◽  
Rat Skeletal Muscle ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Glut4 Expression ◽  
Edl Muscle ◽  
Glut4 Gene Expression

The purpose of this study was to investigate the potential role of creatine in GLUT4 gene expression in rat skeletal muscle. Female Wistar rats were fed normal rat chow (controls) or chow containing 2% creatine monohydrate ad libitum for 3 wk. GLUT4 protein levels of creatine-fed rats were significantly increased in extensor digitorum longus (EDL), triceps, and epitrochlearis muscles compared with muscles from controls ( P < 0.05), and triceps GLUT4 mRNA levels were ∼100% greater in triceps muscles from creatine-fed rats than in muscles from controls ( P < 0.05). In epitrochlearis muscles from creatine-fed animals, glycogen content was ∼40% greater ( P < 0.05), and insulin-stimulated glucose transport rates were higher ( P < 0.05) than in epitrochlearis muscles from controls. Despite no changes in [ATP], [creatine], [phosphocreatine], or [AMP], creatine feeding increased AMP-activated protein kinase (AMPK) phosphorylation by 50% in rat EDL muscle ( P < 0.05). Creatinine content of EDL muscle was almost twofold higher for creatine-fed animals than for controls ( P < 0.05). Creatine feeding increased protein levels of myocyte enhancer factor 2 (MEF2) isoforms MEF2A (∼70%, P < 0.05), MEF2C (∼60%, P < 0.05), and MEF2D (∼90%, P < 0.05), which are transcription factors that regulate GLUT4 expression, in creatine-fed rat EDL muscle nuclear extracts. Electrophoretic mobility shift assay showed that DNA binding activity of MEF2 was increased by ∼40% ( P < 0.05) in creatine-fed rat EDL compared with controls. Our data suggest that creatine feeding enhances the nuclear content and DNA binding activity of MEF2 isoforms, which is concomitant with an increase in GLUT4 gene expression.

C/EBP DNA-binding activity is upregulated by a glucocorticoid-dependent mechanism in septic muscle

2002 ◽  
Vol 282 (2) ◽  
pp. R439-R444 ◽  
Author(s):  
Gail Penner ◽  
Gyu Gang ◽  
Xiaoyan Sun ◽  
Curtis Wray ◽  
Per-Olof Hasselgren
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factors ◽  
Dna Binding ◽  
Cecal Ligation ◽  
Binding Activity ◽  
Nuclear Fraction ◽  
Mobility Shift ◽  
Protein Levels ◽  
Dna Binding Activity ◽  
Mobility Shift Assay

Sepsis-induced muscle cachexia is associated with increased expression of several genes in the ubiquitin-proteasome proteolytic pathway, but little is known about the activation of transcription factors in skeletal muscle during sepsis. We tested the hypothesis that sepsis upregulates the expression and activity of the transcription factors CCAAT/enhancer binding protein (C/EBP)-β and -δ in skeletal muscle. Sepsis was induced in rats by cecal ligation and puncture, and control rats were sham operated. C/EBP-β and -δ DNA-binding activity was determined by electrophoretic mobility shift assay and supershift analysis. In addition, C/EBP-β and -δ nuclear protein levels were determined by Western blot analysis. Sepsis resulted in increased DNA-binding activity of C/EBP, and supershift analysis suggested that this reflected activation of the β- and δ-isoforms of C/EBP. Concomitantly, C/EBP-β and -δ protein levels were increased in the nuclear fraction of skeletal muscle. In additional experiments, we tested the role of glucocorticoids in sepsis-induced activation of C/EBP-β and -δ by treating rats with the glucocorticoid receptor antagonist RU-38486. This treatment inhibited the sepsis-induced activation of C/EBP-β and -δ, suggesting that glucocorticoids participate in the upregulation of C/EBP in skeletal muscle during sepsis. The present results suggest that C/EBP-β and -δ are activated in skeletal muscle during sepsis and that this response is, at least in part, regulated by glucocorticoids.

Extinction of insulin gene expression in hybrids between beta cells and fibroblasts is accompanied by loss of the putative beta-cell-specific transcription factor IEF1

1991 ◽  
Vol 11 (3) ◽  
pp. 1547-1552
Author(s):  
D Leshkowitz ◽  
M D Walker
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Binding Activity ◽  
Insulin Gene ◽  
Hybrid Cells ◽  
Dna Binding Activity ◽  
Insulin Producing Cells ◽  
Insulin Gene Expression ◽  
Insulinoma Cells

Insulin-producing cells and fibroblasts were fused to produce hybrid lines. In hybrids derived from both hamster and rat insulinoma cells, no insulin mRNA could be detected in any of seven lines examined by Northern (RNA) analysis despite the presence in each line of the insulin genes of both parental cells. Hybrid cells were transfected with recombinant chloramphenicol acetyltransferase plasmids containing defined segments of the rat insulin I gene 5' flank. We observed no transcriptional activity of the intact insulin enhancer or of IEB2, a critical cis-acting element of the insulin enhancer. IEB2 has previously been shown to interact in vitro with IEF1, a DNA-binding activity observed selectively in insulin-producing cells. Hybrid cells showed no detectable IEF1 activity. Furthermore, the insulin enhancer was unable to reduce transcription directed by the Moloney sarcoma virus enhancer in a double-enhancer construct. Thus, extinction of insulin gene expression in the hybrids apparently does not operate through a direct action of repressors on the insulin enhancer; rather, extinction is accompanied by, and may be caused by, reduced DNA-binding activity of the putative transcriptional activator IEF1.

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.

scholarly journals Overexpression of mitogen-activated protein kinase (ERK1) enhances T- cell cytokine gene expression: role of AP1, NF-AT, and NF-KB

Blood ◽  
1993 ◽  
Vol 82 (8) ◽  
pp. 2470-2477 ◽  
Author(s):  
JH Park ◽  
L Levitt
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Dna Binding ◽  
Map Kinase ◽  
Binding Activity ◽  
Cytokine Gene Expression ◽  
Cytokine Gene ◽  
Dna Binding Activity ◽  
Mitogen Activated Protein

Abstract Transfected Jurkat cells overexpressing extracellular signal-regulated kinase (ERK1), also referred to as mitogen-activated protein (MAP) kinase, were selected by Western blotting assay using anti-ERK1 and antiphosphotyrosine antibodies in combination with a functional MAP kinase assay. We then asked whether enhanced ERK1 expression had any effect on induction of T-cell cytokine genes. The results show that overexpression of ERK1 enhances expression of T-cell interleukin-2 (IL- 2), IL-3, and granulocyte-macrophage colony-stimulating factor mRNA; no change was seen in expression of the alpha-actin gene. DNA-binding activities of the transcription factors AP1, NF-AT, and NF-kB were specifically increased twofold to fourfold in ERK1-overexpressing clones relative to nontransformed or vector-transformed cells, whereas no enhancement of CK1-CK2 protein DNA binding activity was detected after ERK1 overexpression. Additionally, increased NF-AT DNA binding activity was associated with functional enhancement of NF-AT transactivating activity in ERK1-overexpressing cells. These results provide direct evidence for the role of MAP kinase in the regulation of cytokine gene expression and indicate that such regulation is likely mediated through the enhanced DNA binding activity of specific nuclear transcription factors.

Treatment of cultured myotubes with the proteasome inhibitor β-lactone increases the expression of the transcription factor C/EBPβ

2007 ◽  
Vol 292 (1) ◽  
pp. C216-C226 ◽  
Author(s):  
Wei Wei ◽  
Hongmei Yang ◽  
Michael Menconi ◽  
Peirang Cao ◽  
Chester E. Chamberlain ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factor ◽  
Dna Binding ◽  
Proteasome Inhibitor ◽  
Binding Activity ◽  
Dominant Negative ◽  
Dna Binding Activity ◽  
Cultured Myotubes ◽  
Nuclear Levels ◽  
Factor C

The role of the proteasome in the regulation of cellular levels of the transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is poorly understood. We tested the hypothesis that C/EBPβ levels in cultured myotubes are regulated, at least in part, by proteasome activity. Treatment of cultured L6 myotubes, a rat skeletal muscle cell line, with the specific proteasome inhibitor β-lactone resulted in increased nuclear levels of C/EBPβ as determined by Western blotting and immunofluorescent detection. This effect of β-lactone reflected inhibited degradation of C/EBPβ. Surprisingly, the increased C/EBPβ levels in β-lactone-treated myotubes did not result in increased DNA-binding activity. In additional experiments, treatment of the myotubes with β-lactone resulted in increased nuclear levels of growth arrest DNA damage/C/EBP homologous protein (Gadd153/CHOP), a dominant-negative member of the C/EBP family that can form heterodimers with other members of the C/EBP family and block DNA binding. Coimmunoprecipitation and immunofluorescent detection provided evidence that C/EBPβ and Gadd153/CHOP interacted and colocalized in the nuclei of the β-lactone-treated myotubes. When Gadd153/CHOP expression was downregulated by transfection of myotubes with siRNA targeting Gadd153/CHOP, C/EBPβ DNA-binding activity was restored in β-lactone-treated myotubes. The results suggest that C/EBPβ is degraded by a proteasome-dependent mechanism in skeletal muscle cells and that Gadd153/CHOP can interact with C/EBPβ and block its DNA-binding activity. The observations are important because they increase the understanding of the complex regulation of the expression and activity of C/EBPβ in skeletal muscle.

scholarly journals Signaling mechanisms regulating bombesin-mediated AP-1 gene induction in the human gastric cancer SIIA

2000 ◽  
Vol 279 (2) ◽  
pp. C326-C334 ◽  
Author(s):  
Hong Jin Kim ◽  
B. Mark Evers ◽  
David A. Litvak ◽  
Mark R. Hellmich ◽  
Courtney M. Townsend
Keyword(s):  
Gene Expression ◽  
Gastric Cancer ◽  
Protein Kinase ◽  
Dna Binding ◽  
Signaling Pathways ◽  
Binding Activity ◽  
Human Gastric Cancer ◽  
Rapid Induction ◽  
Dna Binding Activity ◽  
Jun B

The hormone bombesin (BBS) and its mammalian equivalent gastrin-releasing peptide (GRP) act through specific GRP receptors (GRP-R) to affect multiple cellular functions in the gastrointestinal tract; the intracellular signaling pathways leading to these effects are not clearly defined. Previously, we demonstrated that the human gastric cancer SIIA possesses GRP-R and that BBS stimulates activator protein-1 (AP-1) gene expression. The purpose of our present study was to determine the signaling pathways leading to AP-1 induction in SIIA cells. A rapid induction of c- jun and jun-B gene expression was noted after BBS treatment; this effect was blocked by specific GRP-R antagonists, indicating that BBS is acting through the GRP-R. The signaling pathways leading to increased AP-1 gene expression were delineated using phorbol 12-myristate 13-acetate (PMA), which stimulates protein kinase C (PKC)-dependent pathways, by forskolin (FSK), which stimulates protein kinase A (PKA)-dependent pathways, and by the use of various protein kinase inhibitors. Treatment with PMA stimulated AP-1 gene expression and DNA binding activity similar to the effects noted with BBS; FSK stimulated jun-B expression but produced only minimal increases of c- jun mRNA and AP-1 binding activity. Pretreatment of SIIA cells with either H-7 or H-8 (primarily PKC inhibitors) inhibited the induction of c- jun and jun-B mRNAs in response to BBS, whereas H-89 (PKA inhibitor) exhibited only minimal effects. Pretreatment with tyrphostin-25, a protein tyrosine kinase (PTK) inhibitor, attenuated the BBS-mediated induction of c- jun and jun-B, but the effect was not as pronounced as with H-7. Collectively, our results demonstrate that BBS acts through its receptor to produce a rapid induction of both c- jun and jun-B mRNA and AP-1 DNA binding activity in the SIIA human gastric cancer. Moreover, this induction of AP-1, in response to BBS, is mediated through both PKC- and PTK-dependent signal transduction pathways with only minimal involvement of PKA.

Efficient transcription of the glycolytic gene ADH1 and three translational component genes requires the GCR1 product, which can act through TUF/GRF/RAP binding sites

1990 ◽  
Vol 10 (2) ◽  
pp. 859-862
Author(s):  
G M Santangelo ◽  
J Tornow
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Dna Binding ◽  
Binding Sites ◽  
Binding Activity ◽  
Heterologous Gene ◽  
Dna Binding Activity ◽  
Glycolytic Gene

Glycolytic gene expression in Saccharomyces cerevisiae is thought to be activated by the GCR and TUF proteins. We tested the hypothesis that GCR function is mediated by TUF/GRF/RAP binding sites (UASRPG elements). We found that UASRPG-dependent activation of a heterologous gene and transcription of ADH1, TEF1, TEF2, and RP59 were sensitive to GCR1 disruption. GCR is not required for TUF/GRF/RAP expression or in vitro DNA-binding activity.

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