Abstract WMP81: FGF21 Reduces Post-Stroke Blood Brain Barrier Damage in Diabetic db/db Male Mice

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Yinghua Jiang ◽  
Ning Liu ◽  
Xiaoying Wang
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Junctional Complex ◽  
Fibroblast Growth Factor 21 ◽  
Nuclear Fraction ◽  
Mrna Levels ◽  
Protective Effects ◽  
Post Stroke ◽  
Dna Binding Activity ◽  
Bbb Permeability

Background and Purpose: Our previous studies demonstrated that recombinant human Fibroblast growth factor 21 (rFGF21), an endocrine member of the FGF family is potently beneficial for improving long-term neurological outcomes of type 2 diabetes (T2D) stroke mice. Here we tested hypothesis that rFGF21 protects against post-stroke BBB damage by PPARγ activation of cerebral micovascular endothelium. Methods: T2D db/db mice and their non-diabetic counterparts db/+ mice were subjected to focal stroke of dMCAO. Four experimental groups: 1) db/+ stroke, 2) db/db stroke, 3) db/db stroke+rFGF21, and 4) db/db stroke+rFGF21+GW9662. rFGF21 (1.5mg/kg, i.p.) was injected at 6 hours after stroke and PPARγ inhibitor GW9662 (4mg/kg, i.p.) was injected 30 min prior to rFGF21 treatment. At 24 hours post-stroke, we collected peri-infarct nuclear fraction for PPARγ-DNA binding activity assay using EMSA, microvascular isolation for RT-PCR analyzing mRNA levels of proteins constituting BBB junctional complex (occluding, clauding-5, VE-cadherin and ZO-1) and PPARγ targeted downstream genes (CD36 and FABP4) as indicators of PPARγ activity in microvasculature. BBB permeability was assessed by measuring 3kDa FITC-dextran or Evans blue extravasations at 48 hour post-stroke. Results: Ischemic stroke induced a significant decrease of PPARγ-DNA binding activity and mRNA levels of BBB junctional proteins in peri-infarct area, and a significant increase of BBB permeability in diabetic db/db stroke mice compared to db/+ stroke mice. Changes of mRNA levels of CD36 and FABP4 in brain microvascular isolation were consistent with changes of PPARγ-DNA binding activity. rFGF21 administration significantly increased PPARγ-DNA binding activity, elevated mRNA levels of BBB junctional complex proteins and ameliorated BBB leakage. However, pre-treatment of GW9662 partially abolished the post-stroke BBB protective effects of rFGF21. Conclusions: rFGF21 has strong protective effects in acute BBB leakage after stroke, and the underlying mechanisms is partially via increase in PPARγ-DNA binding activity and mRNA expression of BBB junctional complex proteins. Together with our previous investigations, rFGF21 might be a promising candidate for treating diabetic stroke.

scholarly journals FGF21 Protects against Aggravated Blood-Brain Barrier Disruption after Ischemic Focal Stroke in Diabetic db/db Male Mice via Cerebrovascular PPARγ Activation

2020 ◽  
Vol 21 (3) ◽  
pp. 824 ◽  
Author(s):  
Yinghua Jiang ◽  
Li Lin ◽  
Ning Liu ◽  
Qingzhi Wang ◽  
Jing Yuan ◽  
...  
Keyword(s):  
Dna Binding ◽  
Blood Brain Barrier ◽  
Binding Activity ◽  
Brain Barrier ◽  
Fibroblast Growth Factor 21 ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Dna Binding Activity ◽  
Blood Brain ◽  
Junction Protein

Recombinant fibroblast growth factor 21 (rFGF21) has been shown to be potently beneficial for improving long-term neurological outcomes in type 2 diabetes mellitus (T2DM) stroke mice. Here, we tested the hypothesis that rFGF21 protects against poststroke blood–brain barrier (BBB) damage in T2DM mice via peroxisome proliferator-activated receptor gamma (PPARγ) activation in cerebral microvascular endothelium. We used the distal middle cerebral occlusion (dMCAO) model in T2DM mice as well as cultured human brain microvascular endothelial cells (HBMECs) subjected to hyperglycemic and inflammatory injury in the current study. We detected a significant reduction in PPARγ DNA-binding activity in the brain tissue and mRNA levels of BBB junctional proteins and PPARγ-targeting gene CD36 and FABP4 in cerebral microvasculature at 24 h after stroke. Ischemic stroke induced a massive BBB leakage two days after stroke in T2DM mice compared to in their lean controls. Importantly, all abnormal changes were significantly prevented by rFGF21 administration initiated at 6 h after stroke. Our in vitro experimental results also demonstrated that rFGF21 protects against hyperglycemia plus interleukin (IL)-1β-induced transendothelial permeability through upregulation of junction protein expression in an FGFR1 activation and PPARγ activity elevation-dependent manner. Our data suggested that rFGF21 has strong protective effects on acute BBB leakage after diabetic stroke, which is partially mediated by increasing PPARγ DNA-binding activity and mRNA expression of BBB junctional complex proteins. Together with our previous investigations, rFGF21 might be a promising candidate for treating diabetic stroke.

CREB trans-activates the murine H+-K+-ATPase α2-subunit gene

2004 ◽  
Vol 287 (4) ◽  
pp. C903-C911 ◽  
Author(s):  
Xiangyang Xu ◽  
Wenzheng Zhang ◽  
Bruce C. Kone
Keyword(s):  
Dna Binding ◽  
Transcriptional Control ◽  
Luciferase Activity ◽  
Collecting Duct ◽  
Binding Activity ◽  
Dominant Negative ◽  
Proximal Promoter ◽  
Mrna Levels ◽  
Dna Binding Activity

Despite its key role in potassium homeostasis, transcriptional control of the H+-K+-ATPase α2-subunit (HKα2) gene in the collecting duct remains poorly characterized. cAMP increases H+-K+-ATPase activity in the collecting duct, but its role in activating HKα2 transcription has not been explored. Previously, we demonstrated that the proximal 177 bp of the HKα2 promoter confers basal collecting duct-selective expression. This region contains several potential cAMP/Ca2+-responsive elements (CRE). Accordingly, we examined the participation of CRE-binding protein (CREB) in HKα2 transcriptional control in murine inner medullary collecting duct (mIMCD)-3 cells. Forskolin and vasopressin induced HKα2 mRNA levels, and CREB overexpression stimulated the activity of HKα2 promoter-luciferase constructs. Serial deletion analysis revealed that CREB inducibility was retained in a construct containing the proximal 100 bp of the HKα2 promoter. In contrast, expression of a dominant negative inhibitor (A-CREB) resulted in 60% lower HKα2 promoter-luciferase activity, suggesting that constitutive CREB participates in basal HKα2 transcriptional activity. A constitutively active CREB mutant (CREB-VP16) strongly induced HKα2 promoter-luciferase activity, whereas overexpression of CREBdLZ-VP16, which lacks the CREB DNA-binding domain, abolished this activation. In vitro DNase I footprinting and gel shift/supershift analysis of the proximal promoter with recombinant glutathione S-transferase (GST)-CREB-1 and mIMCD-3 cell nuclear extracts revealed sequence-specific DNA-CREB-1 complexes at −86/−60. Mutation at three CRE-like sequences within this region abolished CREB-1 DNA-binding activity and abrogated CREB-VP16 trans-activation of the HKα2 promoter. In contrast, mutation of the neighboring −104/−94 κβ element did not alter CREB-VP16 trans-activation of the HKα2 promoter. Thus CREB-1, binding to one or more CRE-like elements in the −86/−60 region, trans-activates the HKα2 gene and may represent an important link between rapid and delayed effects of cAMP on HKα2 activity.

scholarly journals AP1 Regulation of Proliferation and Initiation of Apoptosis in Erythropoietin-Dependent Erythroid Cells

1998 ◽  
Vol 18 (7) ◽  
pp. 3699-3707 ◽  
Author(s):  
Sarah M. Jacobs-Helber ◽  
Amittha Wickrema ◽  
Michael J. Birrer ◽  
Stephen T. Sawyer
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Dominant Negative ◽  
Stress Factors ◽  
Erythroid Cell ◽  
Mrna Levels ◽  
Erythroid Cells ◽  
Dna Binding Activity ◽  
Regulation Of Proliferation ◽  
Induction Of Apoptosis

ABSTRACT The transcription factor AP1 has been implicated in the induction of apoptosis in cells in response to stress factors and growth factor withdrawal. We report here that AP1 is necessary for the induction of apoptosis following hormone withdrawal in the erythropoietin (EPO)-dependent erythroid cell line HCD57. AP1 DNA binding activity increased upon withdrawal of HCD57 cells from EPO. A dominant negative AP1 mutant rendered these cells resistant to apoptosis induced by EPO withdrawal and blocked the downregulation of Bcl-XL. JunB is a major binding protein in the AP1 complex observed upon EPO withdrawal; JunB but not c-Jun was present in the AP1 complex 3 h after EPO withdrawal in HCD57 cells, with a concurrent increase injunB message and protein. Furthermore, analysis of AP1 DNA binding activity in an apoptosis-resistant subclone of HCD57 revealed a lack of induction in AP1 DNA binding activity and no change injunB mRNA levels upon EPO withdrawal. In addition, we determined that c-Jun and AP1 activities correlated with EPO-induced proliferation and/or protection from apoptosis. AP1 DNA binding activity increased over the first 3 h following EPO stimulation of HCD57 cells, and suppression of AP1 activity partially inhibited EPO-induced proliferation. c-Jun but not JunB was present in the AP1 complex 3 h after EPO addition. These results implicate AP1 in the regulation of proliferation and survival of erythroid cells and suggest that different AP1 factors may play distinct roles in both triggering apoptosis (JunB) and protecting erythroid cells from apoptosis (c-Jun).

Nitric oxide-induced reduction of lung cell and whole lung thioredoxin expression is regulated by NF-κB

1999 ◽  
Vol 277 (4) ◽  
pp. L787-L793 ◽  
Author(s):  
Jianliang Zhang ◽  
Leonard W. Velsor ◽  
Jawaharlal M. Patel ◽  
Edward M. Postlethwait ◽  
Edward R. Block
Keyword(s):  
Nitric Oxide ◽  
Dna Binding ◽  
Nuclear Factor Κb ◽  
Binding Activity ◽  
Nuclear Fraction ◽  
Cytosol Fraction ◽  
Intact Mouse ◽  
Α Subunit ◽  
Dna Binding Activity ◽  
Mouse Lungs

We examined whether nitric oxide (NO)-induced inhibition of thioredoxin (Thx) expression is regulated by a mechanism mediated by a transcription factor, i.e., nuclear factor-κB (NF-κB), in cultured porcine pulmonary artery endothelial cells (PAEC) and in mouse lungs. Western blot analysis revealed that IκB-α content was reduced by 20 and 60% in PAEC exposed to 8.5 ppm NO for 2 and 24 h, respectively. NO exposure also caused significant reductions of cytosol fraction p65 and p52 content in PAEC. The nuclear fraction p65 and p52 contents were significantly reduced only in PAEC exposed to NO for 24 h. Exposure to NO resulted in a 50% reduction of p52 mRNA but not of the IκB-α subunit. DNA binding activity of the oligonucleotide encoding the NF-κB sequence in the Thxgene was significantly reduced in PAEC exposed to NO for 24 h. Exposure of mice to 10 ppm NO for 24 h resulted in a significant reduction of lung Thx and IκB-α mRNA and protein expression and in the oligonucleotide encoding Thx and NF-κB/DNA binding. These results 1) demonstrate that the effects of NO exposure on Thx expression in PAEC are comparable to those observed in intact lung and 2) suggest that reduced expression of the NF-κB subunit, leading to reduced NF-κB/DNA binding, is associated with the loss of Thx expression in PAEC and in intact mouse lungs.

Imatinib Induced Re-Activation of FoxO3 Transcription Factor in CML Is Responsible for the Induction of a Quiescent Status of CD34 Leukaemic Progenitor Cells.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1090-1090
Author(s):  
Daniela Cilloni ◽  
Cristina Panuzzo ◽  
Francesca Messa ◽  
Francesca Arruga ◽  
Enrico Bracco ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Dna Binding ◽  
Progenitor Cells ◽  
Binding Activity ◽  
Mrna Levels ◽  
Dna Binding Activity ◽  
Cd34 Cells

Abstract The FoxO family of transcription factors is regulated by PI3K/Akt induced phosphorylation resulting in nuclear exclusion and degradation. Nuclear FoxO transcribes proapoptotic molecules and cell cycle inhibitors. In CML cells the TK activity of Bcr-Abl leads to the abnormal activation of downstream effectors including PI3K/Akt. The aim of this study was to investigate the role of FoxO3 in Bcr-Abl induced apoptotic arrest and cell growth and the effect of imatinib (IM) induced re-activation of FoxO3 activity in CML progenitor cells. BM cells were collected from 52 CML patients and 20 healthy donors. The expression level of FoxO3 was tested by RQ-PCR. The protein amount and localization was analyzed by Western blot and immunofluorescence, DNA binding activity was measured by EMSA. In addition, FoxO3 was analyzed in CML primary cells and CD34+ cells after IM incubation. Cell cycle and the expression levels of CD47, which has been demonstrated to increased during progression through the cell cycle and stem cell mobilization, was measured by FACS in CD34+ cell population. In addition K562 cells was transfected with pECE-FoxO3 to clarify FoxO3 effects on cell growth and apoptosis. Finally we used our already set up model of Drosophila melanogaster (Dm) transgenic for human Bcr-Abl to study the pathway leading to FoxO3 inactivation. We found that, despite either FoxO3 mRNA levels or protein amount are similar in CML cells compared to controls, FoxO3 protein is equally distributed in the nucleus and cytoplasm in controls but it is completely cytoplasmatic in CML cells and it enters the nucleus during in vivo IM treatment or in vitro IM incubation. Additionally, FoxO3 DNA binding activity in CML patients is completely absent at diagnosis and reappears after IM treatment. Moreover FoxO3 overexpression in transfected cells results into a 49±9 % reduction of proliferation which was further reduced of 75±5 % after IM incubation. Furthermore, we demonstrated that IM incubation results into the reactivation of FoxO3 in Ph+ CD34+ cells inducing quiescence into this population as demonstrated by the comparison of cell cycle kinetics and by a decreased expression of CD47. Finally, the progeny obtained from the crossbreeding of Bcr-Abl flies and flies transgenic for FoxO showed a rescue of FoxO phenotype demonstrating that FoxO inactivation is Bcr-Abl mediated. Overall, these in vitro and in vivo experiments suggest that FoxO3 is inactivated in CML cells and its delocalization is mainly dependant from Bcr-Abl activity. The antiproliferative activity of IM may be mediated by FoxO3 re-localization. On the other side, FoxO3 re-activation induced by IM results into a quiescence of Bcr-Abl CD34+ progenitor cells, which raises a hypothesis that FoxO3 could play a role in IM resistance. This investigation was conducted by CML Correlative Studies Network (CCSN), TOPS, which is sponsored by Novartis Oncology

Arsenite inhibits interleukin-6 production in human intestinal epithelial cells by down-regulating nuclear factor-κB activity

2002 ◽  
Vol 103 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Dan D. HERSHKO ◽  
Bruce W. ROBB ◽  
Eric S. HUNGNESS ◽  
Guangju LUO ◽  
Xialing GUO ◽  
...  
Keyword(s):  
Dna Binding ◽  
Interleukin 6 ◽  
Sodium Arsenite ◽  
Nuclear Factor Κb ◽  
Inhibitory Effect ◽  
Binding Activity ◽  
Mrna Levels ◽  
Nuclear Factor ◽  
Mobility Shift ◽  
Dna Binding Activity

Previous studies have suggested that the production of interleukin-6 (IL-6) is increased in the intestinal mucosa during inflammation, and that nuclear factor-κB (NF-κB) is an important regulator of the IL-6 gene in the enterocyte. We tested the hypothesis that sodium arsenite inhibits IL-6 production in stimulated enterocytes and that this effect of arsenite is caused by down-regulation of NF-κB activity. Cultured Caco-2 cells were treated with sodium arsenite and were then stimulated with IL-1β. IL-6 production and gene expression were determined by ELISA and reverse transcriptase–PCR respectively. NF-κB DNA binding activity was determined by electrophoretic mobility shift assay. IL-1β increased NF-κB DNA binding activity, IL-6 mRNA levels and IL-6 production. These effects of IL-1β were inhibited by treatment of the cells with sodium arsenite in a dose- and time-dependent fashion. When cells were transfected with a plasmid expressing the p65 subunit of NF-κB, the inhibitory effect of sodium arsenite on NF-κB activity and IL-6 production was blunted. These results suggest that sodium arsenite inhibits IL-6 production in enterocytes subjected to an inflammatory stimulus, and that this effect, at least in part, reflects down-regulated NF-κB activity.

Activity of hepatocyte nuclear factor 1α and hepatocyte nuclear factor 1β isoforms is differently affected by the inhibition of protein phosphatases 1/2A

2001 ◽  
Vol 354 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Véronique CARRIÈRE ◽  
Michel LACASA ◽  
Monique ROUSSET
Keyword(s):  
Dna Binding ◽  
Binding Capacity ◽  
Protein Phosphatases ◽  
Physiological Role ◽  
Binding Activity ◽  
Mrna Levels ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Gene Encoding ◽  
Dna Binding Activity

Phosphorylation/dephosphorylation processes are known to control the activity of several transcription factors. The nutrition-dependent expression of sucrase–isomaltase and Na+/glucose co-transporter 1, two proteins implicated in the intestinal absorption of glucose, has been shown to be closely related to modifications of hepatocyte nuclear factor 1 (HNF1) activity. This study was conducted to determine whether phosphorylation/dephosphorylation processes could control HNF1 activity. We show that expression of the gene encoding sucrase–isomaltase is inhibited in the enterocytic Caco-2 clone TC7 by okadaic acid at a concentration that is known to inhibit protein phosphatases 1/2A and that does not affect cell viability. At the same concentration, phosphorylation of the HNF1α and HNF1β isoforms is greatly enhanced and their DNA-binding capacity is decreased. The phosphorylation state of HNF1β isoforms directly affects their DNA-binding capacity. In contrast, the decreased DNA-binding activity of the HNF1α isoforms, which was observed after the inhibition of protein phosphatases 1/2A, is due to a net decrease in their total cellular and nuclear amounts. Such an effect results from a decrease in both the HNF1α mRNA levels and the half-life of the protein. This is the first evidence for the implication of protein phosphatases 1/2A in the control of the activity of HNF1 isoforms. Moreover, these results emphasize a physiological role for the balance between phosphatases and kinases in the nutrition-dependent regulation of HNF1-controlled genes.

Ceramide decreases surfactant protein B gene expression via downregulation of TTF-1 DNA binding activity

2006 ◽  
Vol 290 (2) ◽  
pp. L351-L358 ◽  
Author(s):  
Loretta Sparkman ◽  
Hemakumar Chandru ◽  
Vijayakumar Boggaram
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Dna Binding ◽  
Promoter Activity ◽  
Surfactant Protein ◽  
Binding Activity ◽  
Mrna Levels ◽  
Dna Binding Activity ◽  
Surfactant Protein B ◽  
Tnf Α

Ceramide, a sphingolipid, is an important signaling molecule in the inflammatory response. Mediators of acute lung injury such as TNF-α, platelet-activating factor, and Fas/Apo ligand stimulate sphingomyelin hydrolysis to increase intracellular ceramide levels. Surfactant protein B (SP-B), a hydrophobic protein of pulmonary surfactant, is essential for surfactant function and lung stability. In this study we investigated the effects of ceramide on SP-B gene expression in H441 lung epithelial cells. Ceramide decreased SP-B mRNA levels in control and dexamethasone-treated cells after 24-h incubation and inhibition of SP-B mRNA was associated with inhibition of immunoreactive SP-B. In transient transfections assays, ceramide inhibited SP-B promoter activity, indicating that the inhibitory effects are exerted at the transcriptional level. Deletion mapping experiments showed that the ceramide-responsive region is located within the −233/−80-bp region of human SP-B promoter. Electrophoretic mobility shift and reporter assays showed that ceramide reduced the DNA binding activity and transactivation capability of thyroid transcription factor 1 (TTF-1/Nkx2.1), a key factor for SP-B promoter activity. Collectively these data showed that ceramide inhibits SP-B gene expression by reducing the DNA biding activity of TTF-1/Nkx2.1 transcription factor. Protein kinase C inhibitor bisindolylmaleimide and the protein tyrosine kinase inhibitor genistein partially reversed ceramide inhibition, indicating that protein kinases play important roles in the ceramide inhibition of SP-B gene expression. Chemical inhibitors of de novo ceramide synthesis and sphingomyelin hydrolysis had no effect on TNF-α inhibition of SP-B promoter activity and mRNA levels, suggesting that ceramide does not play a role in the inhibition.

scholarly journals Mycoplasma genitaliumLipoproteins Induce Human Monocytic Cell Expression of Proinflammatory Cytokines and Apoptosis by Activating Nuclear FactorκB

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Yimou Wu ◽  
Hong Qiu ◽  
Yanhua Zeng ◽  
Xiaoxing You ◽  
Zhongliang Deng ◽  
...  
Keyword(s):  
Dna Binding ◽  
Proinflammatory Cytokines ◽  
Cell Apoptosis ◽  
Molecular Mechanisms ◽  
Binding Activity ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Monocytic Cell ◽  
Dna Binding Activity ◽  
Human Monocytic Cell

This study was designed to investigate the molecular mechanisms responsible for the induction of proinflammatory cytokines gene expression and apoptosis in human monocytic cell line THP-1 stimulated by lipoproteins (LPs) prepared fromMycoplasma genitalium. Cultured cells were stimulated withM. genitaliumLP to analyze the production of proinflammatory cytokines and expression of their mRNA by ELISA and RT-PCR, respectively. Cell apoptosis was also detected by Annexin V-FITC-propidium iodide (PI) staining and acridine orange (AO)-ethidium bromide (EB) staining. The DNA-binding activity of nuclear factor-κB (NF-κB) was assessed by electrophoretic mobility shift assay (EMSA). Results showed that LP stimulated THP-1 cells to produce tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), and IL-6 in a dose-dependent manner. The mRNA levels were also upregulated in response to LP stimulation. LPs were also found to increase the DNA-binding activity of NF-κB, a possible mechanism for the induction of cytokine mRNA expression and the cell apoptosis. These effects were abrogated by PDTC, an inhibitor of NF-κB. Our results indicate thatM. genitalium-derived LP may be an important etiological factor of certain diseases due to the ability of LP to produce proinflammatory cytokines and induction of apoptosis, which is probably mediated through the activation of NF-κB.

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.

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