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Shuxia Wang - One of the best experts on this subject based on the ideXlab platform.
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Role of Upstream Stimulatory Factor 2 in diabetic nephropathy
Frontiers in Biology, 2015Co-Authors: Shuxia WangAbstract:Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD). About 20%–30% of people with type 1 and type 2 diabetes develop DN. DN is characterized by both glomerulosclerosis with thickening of the glomerular basement membrane and mesangial matrix expansion, and tubulointerstitial fibrosis. Hyperglycemia and the activation of the intra-renal renin-angiotensin system (RAS) in diabetes have been suggested to play a critical role in the pathogenesis of DN. However, the mechanisms are not well known. Studies from our laboratory demonstrated that the transcription Factor—Upstream Stimulatory Factor 2 (USF2) is an important regulator of DN. Moreover, the renin gene is a downstream target of USF2. Importantly, USF2 transgenic (Tg) mice demonstrate a specific increase in renal renin expression and angiotensin II (AngII) levels in kidney and exhibit increased urinary albumin excretion and extracellular matrix deposition in glomeruli, supporting a role for USF2 in the development of diabetic nephropathy. In this review, we summarize our findings of the mechanisms by which diabetes regulates USF2 in kidney cells and its role in regulation of renal renin-angiotensin system and the development of diabetic nephropathy.
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High Glucose Upregulates Upstream Stimulatory Factor 2 in Human Renal Proximal Tubular Cells through Angiotensin II-Dependent Activation of CREB
Nephron. Experimental nephrology, 2010Co-Authors: Nishant P. Visavadiya, Shuxia WangAbstract:We have previously demonstrated that a transcription Factor, Upstream Stimulatory Factor 2 (USF2), regulates glucose-induced thrombospondin 1 expression and transforming growth Factor-β activity in mesangial cells, and plays an important role in diabetic glomerulopathy. In this study, we determined whether USF2 expression in renal proximal tubular cells is regulated by glucose and contributes to diabetic tubulointerstitial fibrosis. Human renal proximal tubular cells (HK-2 cells) were treated with normal- or high-glucose medium for 24 h. After treatment, real-time PCR or immunoblotting was used to determine the expression of USF2 and other components of the renin-angiotensin system in HK-2 cells. High glucose upregulated USF2 expression and increased extracellular matrix accumulation in HK-2 cells; both were inhibited by siRNA-mediated USF2 knockdown. In addition, high glucose stimulated angiotensinogen and renin expression, increased renin activity, and resulted in increased angiotensin II formation. Treatment of HK-2 cells with an angiotensin II receptor 1 (AT1) blocker--losartan--prevented high-glucose-induced USF2 expression and high-glucose-enhanced phosphorylation of CREB (cAMP response element-binding protein). Our data established that high glucose stimulated USF2 expression in HK-2 cells, at least in part, through angiotensin II-AT1-dependent activation of CREB, which can contribute to diabetic tubulointerstitial fibrosis. Copyright © 2010 S. Karger AG, Basel.
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High Glucose Upregulates Upstream Stimulatory Factor 2 in Human Renal Proximal Tubular Cells through Angiotensin II-Dependent Activation of CREB
Nephron. Experimental nephrology, 2010Co-Authors: Nishant P. Visavadiya, Shuxia WangAbstract:Background/Aims: We have previously demonstrated that a transcription Factor, Upstream Stimulatory Factor 2 (USF2), regulates glucose-induced thrombospondin 1 expression and transfo
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Glycated albumin upregulates Upstream Stimulatory Factor 2 gene transcription in mesangial cells
American journal of physiology. Renal physiology, 2010Co-Authors: Shuxia WangAbstract:Diabetic nephropathy (DN) is the most common cause of end-stage renal failure. We previously demonstrated that a transcription Factor called Upstream Stimulatory Factor 2 (USF2) was upregulated in the kidneys from diabetic animals in vivo as well as in mesangial cells (MCs) exposed to high-glucose media in vitro. USF2 mediates glucose-induced thrombospondin 1 expression and transforming growth Factor-beta activity in MCs and plays a role in DN. Glycated proteins have been shown to accumulate in the kidneys of diabetic patients and contribute to DN. However, whether glycated proteins regulate USF2 expression in MCs and play a role in DN is unknown. In the present studies, we determined the effect of glycated albumin on UFS2 gene expression in primary rat MCs. We found that glycated albumin upregulated USF2 expression (mRNA and protein) in a dose- and time-dependent manner. We also demonstrated that glycated albumin stimulated USF2 gene expression at the transcriptional level. By using the luciferase-promoter deletion assay, site-directed mutagenesis, and transactivation assay, we identified a glycated albumin-responsive region in the USF2 gene promoter (-837 to -430, relative to the transcription start site) and demonstrated that glycated albumin-induced USF2 expression was mediated through NF-kappaB-dependent transactivation of the USF2 promoter. Furthermore, glycated albumin increased nuclear NF-kappaB subunit-p65 protein levels. siRNA-mediated p65 knockdown prevented glycated albumin-induced USF2 gene expression (promoter activity, mRNA, and protein levels). Taken together, these data suggest that glycated albumin upregulated USF2 gene transcription in MCs through NF-kappaB-dependent transactivation of the USF2 promoter.
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Glycated albumin upregulates Upstream Stimulatory Factor 2 gene transcription in mesangial cells
American journal of physiology. Renal physiology, 2010Co-Authors: Shuxia WangAbstract:Diabetic nephropathy (DN) is the most common cause of end-stage renal failure. We previously demonstrated that a transcription Factor called Upstream Stimulatory Factor 2 (USF2) was upregulated in ...
Michele Sawadogo - One of the best experts on this subject based on the ideXlab platform.
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In Vivo Regulation of Follicle-Stimulating Hormone Receptor by the Transcription Factors Upstream Stimulatory Factor 1 and Upstream Stimulatory Factor 2 Is Cell Specific
Endocrinology, 2008Co-Authors: Brian P Hermann, Kaori I Hornbaker, Daren A Rice, Michele Sawadogo, Leslie L HeckertAbstract:Pituitary FSH promotes pubertal timing and normal gametogenesis by binding its receptor (FSHR) located on Sertoli and granulosa cells of the testis and ovary, respectively. Studies on Fshr transcription provide substantial evidence that Upstream Stimulatory Factor (USF) 1 and USF2, basic helix-loop-helix leucine zipper proteins, regulate Fshr through an E-box within its promoter. However, despite the strong in vitro support for USF1 and USF2 in Fshr regulation, there is currently no in vivo corroborating evidence. In the present study, chromatin immunoprecipitation demonstrated specific binding of USF1 and USF2 to the Fshr promoter in both Sertoli and granulosa cells, in vivo. Control cells lacking Fshr expression showed no USF-Fshr promoter binding, thus correlating USF-promoter binding to gene activity. Evaluation of Fshr expression in Usf1 and Usf2 null mice further explored USF’s role in Fshr transcription. Loss of either gene significantly reduced ovarian Fshr levels, whereas testis levels were unalt...
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In Vivo Regulation of Follicle-Stimulating Hormone Receptor by the Transcription Factors Upstream Stimulatory Factor 1 and Upstream Stimulatory Factor 2 Is Cell Specific
Endocrinology, 2008Co-Authors: Brian P Hermann, Kaori I Hornbaker, Daren A Rice, Michele Sawadogo, Leslie L HeckertAbstract:Pituitary FSH promotes pubertal timing and normal gametogenesis by binding its receptor (FSHR) located on Sertoli and granulosa cells of the testis and ovary, respectively. Studies on Fshr transcription provide substantial evidence that Upstream Stimulatory Factor (USF) 1 and USF2, basic helix-loop-helix leucine zipper proteins, regulate Fshr through an E-box within its promoter. However, despite the strong in vitro support for USF1 and USF2 in Fshr regulation, there is currently no in vivo corroborating evidence. In the present study, chromatin immunoprecipitation demonstrated specific binding of USF1 and USF2 to the Fshr promoter in both Sertoli and granulosa cells, in vivo. Control cells lacking Fshr expression showed no USF-Fshr promoter binding, thus correlating USF-promoter binding to gene activity. Evaluation of Fshr expression in Usf1 and Usf2 null mice further explored USF's role in Fshr transcription. Loss of either gene significantly reduced ovarian Fshr levels, whereas testis levels were unaltered. Chromatin immunoprecipitation analysis of USF-Fshr promoter binding in Usf-null mice indicated differences in the composition of promoter-bound USF dimers in granulosa and Sertoli cells. Promoter-bound USF dimer levels declined in granulosa cells from both null mice, despite increased USF2 levels in Usf1-null ovaries. However, compensatory increases in promoter-bound USF homodimers were evident in Usf-null Sertoli cells. In summary, this study provides the first in vivo evidence that USF1 and USF2 bind the Fshr promoter and revealed differences between Sertoli and granulosa cells in compensatory responses to USF loss and the USF dimeric composition required for Fshr transcription.
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Molecular characterization and role of bovine Upstream Stimulatory Factor 1 and 2 in the regulation of the prostaglandin G/H synthase-2 promoter in granulosa cells.
The Journal of biological chemistry, 2003Co-Authors: Khampoune Sayasith, Michele Sawadogo, Nadine Bouchard, Jacques G. Lussier, Jean SiroisAbstract:The transcriptional activation of the prostaglandin G/H synthase-2 (PGHS-2) gene in granulosa cells is required for ovulation. To directly study the ability of Upstream Stimulatory Factor 1 (USF1) and USF2 to trans-activate the bovine PGHS-2 promoter in granulosa cells, USF1 or USF2 expression vectors were cotransfected with the PGHS-2/luciferase (LUC) chimeric construct, -149/-2PGHS-2.LUC. Results revealed that overexpression of USF1 or USF2 caused a marked and significant increase in basal and forskolin-inducible promoter activities (p
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Molecular characterization and role of bovine Upstream Stimulatory Factor 1 and 2 in the regulation of the prostaglandin G/H synthase-2 promoter in granulosa cells.
The Journal of biological chemistry, 2003Co-Authors: Khampoune Sayasith, Michele Sawadogo, Nadine Bouchard, Jacques G. Lussier, Jean SiroisAbstract:Abstract The transcriptional activation of the prostaglandin G/H synthase-2 (PGHS-2) gene in granulosa cells is required for ovulation. To directly study the ability of Upstream Stimulatory Factor 1 (USF1) and USF2 to trans-activate the bovine PGHS-2 promoter in granulosa cells, USF1 or USF2 expression vectors were cotransfected with the PGHS-2/luciferase (LUC) chimeric construct, -149/-2PGHS-2.LUC. Results revealed that overexpression of USF1 or USF2 caused a marked and significant increase in basal and forskolin-inducible promoter activities (p < 0.05), and these effects were dependent on the presence of a consensus E-box cis-element within the promoter fragment. Co-transfections with different N- and C-terminal truncated USF mutants led to significant reductions in promoter activation, as compared with full-length constructs (p < 0.05), thus allowing identification of putative bovine USF functional domains. Overexpression of a USF2 truncated mutant lacking the first 220 residues (U2Δ1-220) acted as a dominant negative mutant and blocked endogenous and USF-stimulated PGHS-2 promoter activation. Interestingly, transfections with U2Δ1-220 blocked the forskolin-dependent induction of PGHS-2 mRNA in granulosa cells, whereas transfections with full-length USF2 increased PGHS-2 transcript levels. Immunoblot analyses confirmed overexpression of full-length and truncated USF proteins, and electrophoretic mobility shift assays (EMSAs) and supershift EMSAs established that the observed effects were dependent on specific interactions between USF proteins and the consensus E-box cis-element. Stimulation of cells with forskolin increased, whereas treatment of extracts with phosphatase decreased USF binding activities to the E-box. Thus, this study presents for the first time direct evidence for a role of USF proteins in the regulation of the PGHS-2 promoter in preovulatory granulosa cells.
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Upstream Stimulatory Factor Regulates Major Histocompatibility Complex Class I Gene Expression: the U2ΔE4 Splice Variant Abrogates E-Box Activity
Molecular and cellular biology, 1999Co-Authors: T. Kevin Howcroft, Michele Sawadogo, Charles Murphy, Jocelyn D. Weissman, Sam J. Huber, Dinah S. SingerAbstract:The tissue-specific expression of major histocompatibility complex class I genes is determined by a series of Upstream regulatory elements, many of which remain ill defined. We now report that a distal E-box element, located between bp −309 and −314 Upstream of transcription initiation, acts as a cell type-specific enhancer of class I promoter activity. The class I E box is very active in a neuroblastoma cell line, CHP-126, but is relatively inactive in the HeLa epithelial cell line. The basic helix-loop-helix leucine zipper proteins Upstream Stimulatory Factor 1 (USF1) and USF2 were shown to specifically recognize the class I E box, resulting in the activation of the downstream promoter. Fine mapping of USF1 and USF2 amino-terminal functional domains revealed differences in their abilities to activate the class I E box. Whereas USF1 contained only an extended activation domain, USF2 contained both an activation domain and a negative regulatory region. Surprisingly, the naturally occurring splice variant of USF2 lacking the exon 4 domain, U2ΔE4, acted as a dominant-negative regulator of USF-mediated activation of the class I promoter. This latter activity is in sharp contrast to the known ability of U2ΔE4 to activate the adenovirus major late promoter. Class I E-box function is correlated with the relative amount of U2ΔE4 in a cell, leading to the proposal that U2ΔE4 modulates class I E-box activity and may represent one mechanism to fine-tune class I expression in various tissues.
Tetsuya Kamataki - One of the best experts on this subject based on the ideXlab platform.
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COMPETITIVE INHIBITION OF THE TRANSCRIPTION OF RABBIT CYP1A1 GENE BY Upstream Stimulatory Factor 1 (USF1)
Drug metabolism reviews, 2001Co-Authors: Yoshiki Takahashi, Tetsuya KamatakiAbstract:The induction of CYP1A1 by 3-methylcholanthrene occurs in neonatal but not in adult rabbits. The expression of aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (Arnt) mRNAs is seen even in adult rabbits. The CYP1A1 inducibility does not seem to be regulated by DNA methylation, known to inhibit the transcription of a gene(s). Preliminary experiments suggest that a constitutive Factor(s) in adult liver nuclear extracts is bound to the core sequence of rabbit xenobiotic-responsive element (XRE). The sequence of rabbit XRE overlaps with that of the Upstream Stimulatory Factor 1 (USF1)-binding site. The AhR/Arnt-mediated activation of XRE-TK/Luc reporter gene in RK13 cells is blocked by transfection with a USF1 expression vector. These results indicate that the XRE of the rabbit CYP1A1 gene is recognized by the basic helix-loop-helix proteins to regulate the expression of CYP1A1 in both an agonistic (AhR/Arnt) and an antagonistic (USF1) manner.
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inhibition of the transcription of cyp1a1 gene by the Upstream Stimulatory Factor 1 in rabbits competitive binding of usf1 with ahr arnt complex
Journal of Biological Chemistry, 1997Co-Authors: Yoshiki Takahashi, Kazuo Nakayama, Susumu Itoh, Yoshiaki Fujiikuriyama, Tetsuya KamatakiAbstract:Abstract A xenobiotic-responsive element (XRE)-binding Factor(s) other than the AhR·Arnt complex was found to inhibit the transcription of CYP1A1 gene in the liver from adult rabbits, known to be nonresponsive to CYP1A1 inducers. The constitutive Factor(s) in liver nuclear extracts bound to the core sequence of XRE. The binding was eliminated by the presence of an excess amount of the AhR·Arnt complex synthesized in vitro. To identify the constitutive Factor(s), a sequence similar to rabbit XRE was sought. It was found that the sequence of rabbit XRE overlapped with that of the Upstream Stimulatory Factor 1 (USF1)-binding site in the mouse metallothionein I promoter. In fact, a super shift assay using a specific antibody against human USF1 indicated that USF1 was capable of binding to rabbit XRE. Additionally, the AhR·Arnt-mediated activation of XRE-TK/Luc reporter gene in RK13 cells was blocked by the transfection with a USF1 expression vector with the amounts of the expression vector transfected. These results indicate that the XRE of the rabbit CYP1A1 gene is recognized by the basic helix-loop-helix proteins to regulate the expression ofCYP1A1 in both an agonistic (AhR·Arnt) and an antagonistic (USF1) manner.
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Inhibition of the Transcription of CYP1A1 Gene by the Upstream Stimulatory Factor 1 in Rabbits COMPETITIVE BINDING OF USF1 WITH AhR·Arnt COMPLEX
The Journal of biological chemistry, 1997Co-Authors: Yoshiki Takahashi, Kazuo Nakayama, Susumu Itoh, Yoshiaki Fujii-kuriyama, Tetsuya KamatakiAbstract:Abstract A xenobiotic-responsive element (XRE)-binding Factor(s) other than the AhR·Arnt complex was found to inhibit the transcription of CYP1A1 gene in the liver from adult rabbits, known to be nonresponsive to CYP1A1 inducers. The constitutive Factor(s) in liver nuclear extracts bound to the core sequence of XRE. The binding was eliminated by the presence of an excess amount of the AhR·Arnt complex synthesized in vitro. To identify the constitutive Factor(s), a sequence similar to rabbit XRE was sought. It was found that the sequence of rabbit XRE overlapped with that of the Upstream Stimulatory Factor 1 (USF1)-binding site in the mouse metallothionein I promoter. In fact, a super shift assay using a specific antibody against human USF1 indicated that USF1 was capable of binding to rabbit XRE. Additionally, the AhR·Arnt-mediated activation of XRE-TK/Luc reporter gene in RK13 cells was blocked by the transfection with a USF1 expression vector with the amounts of the expression vector transfected. These results indicate that the XRE of the rabbit CYP1A1 gene is recognized by the basic helix-loop-helix proteins to regulate the expression ofCYP1A1 in both an agonistic (AhR·Arnt) and an antagonistic (USF1) manner.
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Upstream Stimulatory Factor 1 (USF1) suppresses induction of CYP1A1 mRNA by 3-methylcholanthrene (MC) in HepG2 cells.
Biochemical and biophysical research communications, 1997Co-Authors: Yoshiki Takahashi, Kazuo Nakayama, Susumu Itoh, Tetsuya KamatakiAbstract:Abstract In this study, an endogenous Factor(s) involved in the suppression of the induction of CYP1A1 was studied. Analyzing the sequences, we found that the sequence of xenobiotic responsive element (XRE) in the Upstream region of the humanCYP1A1gene was overlapped with that of the Upstream Stimulatory Factor 1 (USF1)-binding site in mouse metallothionein I promoter. In fact, a gel shift assay using a specific competitor or mutant probes showed that the core sequence of human XRE was specifically recognized by USF1. The amount of USF1 in the nuclear extracts from HepG2 cells was smaller than that from rat and rabbit livers as assayed by the binding to XRE. To determine whether or not USF1 could inhibit the interaction of aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (Arnt) complex with XRE, we transfected USF1-SRα expression vector into HepG2 cells. The results showed that no interaction of AhR/Arnt complex with XRE occurred even when the cells were treated with 2,3,7,8-tetrachlorodibenzofuran (TCDF). Furthermore, the S1 nuclease protection assay showed that the induction of CYP1A1 mRNA by 3-methylcholanthrene (MC) was depressed by the transfection of USF1-SRα into HepG2 cells. Thus, it is highly possible that USF1 negatively regulates the induction of CYP1A1 in humans.
Richard M Obrien - One of the best experts on this subject based on the ideXlab platform.
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Upstream Stimulatory Factor usf and neurogenic differentiation beta cell e box transactivator 2 neurod beta2 contribute to islet specific glucose 6 phosphatase catalytic subunit related protein igrp gene expression
Biochemical Journal, 2003Co-Authors: Cyrus C Martin, Christina A Svitek, James K Oeser, Eva Henderson, Roland Stein, Richard M ObrienAbstract:Islet-specific glucose-6-phosphatase (G6Pase) catalytic-subunit-related protein (IGRP) is a homologue of the catalytic subunit of G6Pase, the enzyme that catalyses the final step of the gluconeogenic pathway. The analysis of IGRP-chloramphenicol acetyltransferase (CAT) fusion-gene expression through transient transfection of islet-derived beta TC-3 cells revealed that multiple promoter regions, located between -306 and -97, are required for maximal IGRP-CAT fusion-gene expression. These regions correlated with trans -acting Factor-binding sites in the IGRP promoter that were identified in beta TC-3 cells in situ using the ligation-mediated PCR (LMPCR) footprinting technique. However, the LMPCR data also revealed additional trans -acting Factor-binding sites located between -97 and +1 that overlap two E-box motifs, even though this region by itself conferred minimal fusion-gene expression. The data presented here show that these E-box motifs are important for IGRP promoter activity, but that their action is only manifest in the presence of distal promoter elements. Thus mutation of either E-box motif in the context of the -306 to +3 IGRP promoter region reduces fusion-gene expression. These two E-box motifs have distinct sequences and preferentially bind NeuroD/BETA2 (neurogenic differentiation/beta-cell E box transactivator 2) and Upstream Stimulatory Factor (USF) in vitro, consistent with the binding of both Factors to the IGRP promoter in situ, as determined using the chromatin-immunoprecipitation (ChIP) assay. Based on experiments using mutated IGRP promoter constructs, we propose a model to explain how the ubiquitously expressed USF could contribute to islet-specific IGRP gene expression.
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Upstream Stimulatory Factor usf and neurogenic differentiation beta cell e box transactivator 2 neurod beta2 contribute to islet specific glucose 6 phosphatase catalytic subunit related protein igrp gene expression
Biochemical Journal, 2003Co-Authors: Cyrus C Martin, Christina A Svitek, James K Oeser, Eva Henderson, Roland Stein, Richard M ObrienAbstract:Islet-specific glucose-6-phosphatase (G6Pase) catalytic-subunit-related protein (IGRP) is a homologue of the catalytic subunit of G6Pase, the enzyme that catalyses the final step of the gluconeogenic pathway. The analysis of IGRP-chloramphenicol acetyltransferase (CAT) fusion-gene expression through transient transfection of islet-derived beta TC-3 cells revealed that multiple promoter regions, located between -306 and -97, are required for maximal IGRP-CAT fusion-gene expression. These regions correlated with trans -acting Factor-binding sites in the IGRP promoter that were identified in beta TC-3 cells in situ using the ligation-mediated PCR (LMPCR) footprinting technique. However, the LMPCR data also revealed additional trans -acting Factor-binding sites located between -97 and +1 that overlap two E-box motifs, even though this region by itself conferred minimal fusion-gene expression. The data presented here show that these E-box motifs are important for IGRP promoter activity, but that their action is only manifest in the presence of distal promoter elements. Thus mutation of either E-box motif in the context of the -306 to +3 IGRP promoter region reduces fusion-gene expression. These two E-box motifs have distinct sequences and preferentially bind NeuroD/BETA2 (neurogenic differentiation/beta-cell E box transactivator 2) and Upstream Stimulatory Factor (USF) in vitro, consistent with the binding of both Factors to the IGRP promoter in situ, as determined using the chromatin-immunoprecipitation (ChIP) assay. Based on experiments using mutated IGRP promoter constructs, we propose a model to explain how the ubiquitously expressed USF could contribute to islet-specific IGRP gene expression.
Lihua Shi - One of the best experts on this subject based on the ideXlab platform.
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Activation of renal renin-angiotensin system in Upstream Stimulatory Factor 2 transgenic mice
American journal of physiology. Renal physiology, 2008Co-Authors: Lihua Shi, Shu Liu, Dejan Nikolic, Shuxia WangAbstract:Previously we demonstrated that Upstream Stimulatory Factor 2 (USF2) transgenic (Tg) mice developed nephropathy including albuminuria and glomerular hypertrophy, accompanied by increased transformi...
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High glucose levels upregulate Upstream Stimulatory Factor 2 gene transcription in mesangial cells
Journal of cellular biochemistry, 2008Co-Authors: Lihua Shi, Shu Liu, Dejan Nikolic, Shuxia WangAbstract:Previously, we demonstrated that Upstream Stimulatory Factor 2 (USF2) mediates high glucose-induced thrombospondin1 (TSP1) gene expression and TGF-beta activity in glomerular mesangial cells and plays a role in diabetic renal complications. In the present studies, we further determined the molecular mechanisms by which high glucose levels regulate USF2 gene expression. In primary rat mesangial cells, we found that glucose treatment time and dose-dependently up-regulated USF2 expression (mRNA and protein). By using cycloheximide to block the de novo protein synthesis, similar rate of USF2 degradation was found under either normal glucose or high glucose conditions. USF2 mRNA stability was not altered by high glucose treatment. Furthermore, high glucose treatment stimulated USF2 gene promoter activity. By using the luciferase-promoter deletion assay, site-directed mutagenesis, and transactivation assay, we identified a glucose-responsive element in the USF2 gene promoter (-1,740 to -1,620, relative to the transcription start site) and demonstrated that glucose-induced USF2 expression is mediated through a cAMP-response element-binding protein (CREB)-dependent transactivation of the USF2 promoter. Furthermore, siRNA-mediated CREB knock down abolished glucose-induced USF2 expression. Taken together, these data indicate that high glucose levels up-regulate USF2 gene transcription in mesangial cells through CREB-dependent transactivation of the USF2 promoter.
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High glucose levels upregulate Upstream Stimulatory Factor 2 gene transcription in mesangial cells
Journal of cellular biochemistry, 2008Co-Authors: Lihua Shi, Shu Liu, Dejan Nikolic, Shuxia WangAbstract:Previously, we demonstrated that Upstream Stimulatory Factor 2 (USF2) mediates high glucose-induced thrombospondin1 (TSP1) gene expression and TGF-β activity in glomerular mesangial cells and plays a role in diabetic renal complications. In the present studies, we further determined the molecular mechanisms by which high glucose levels regulate USF2 gene expression. In primary rat mesangial cells, we found that glucose treatment time and dose-dependently up-regulated USF2 expression (mRNA and protein). By using cycloheximide to block the de novo protein synthesis, similar rate of USF2 degradation was found under either normal glucose or high glucose conditions. USF2 mRNA stability was not altered by high glucose treatment. Furthermore, high glucose treatment stimulated USF2 gene promoter activity. By using the luciferase-promoter deletion assay, site-directed mutagenesis, and transactivation assay, we identified a glucose-responsive element in the USF2 gene promoter (−1,740 to −1,620, relative to the transcription start site) and demonstrated that glucose-induced USF2 expression is mediated through a cAMP-response element-binding protein (CREB)-dependent transactivation of the USF2 promoter. Furthermore, siRNA-mediated CREB knock down abolished glucose-induced USF2 expression. Taken together, these data indicate that high glucose levels up-regulate USF2 gene transcription in mesangial cells through CREB-dependent transactivation of the USF2 promoter. J. Cell. Biochem. 103: 1952–1961, 2007. © 2007 Wiley-Liss, Inc.
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Overexpression of Upstream Stimulatory Factor 2 accelerates diabetic kidney injury
American journal of physiology. Renal physiology, 2007Co-Authors: Shu Liu, Lihua Shi, Shuxia WangAbstract:Diabetic nephropathy is the most common cause of end-stage renal failure in the United States. Hyperglycemia is an important Factor in the pathogenesis of diabetic nephropathy. Hyperglycemia upregulates the expression of transforming growth Factor-beta (TGF-beta), which stimulates extracellular matrix deposition in the kidney, contributing to the development of diabetic nephropathy. Our previous studies demonstrated that the transcription Factor, Upstream Stimulatory Factor 2 (USF2), was upregulated by high glucose, which bound to an 18-bp sequence in the thrombospondin 1 (TSP1) gene promoter and regulated high glucose-induced TSP1 expression and TGF-beta activity in mesangial cells, suggesting that USF2 might play a role in the development of diabetic nephropathy. In the present studies, we examined the effect of overexpression of USF2 on the development of diabetic nephropathy. Type 1 diabetes was induced in USF2 transgenic mice [USF2 (Tg)] and their wild-type littermates (WT) by injection of streptozotocin. Four groups of mice were studied: control WT, control USF2 (Tg), diabetic WT, and diabetic USF2 (Tg). Mice were killed after 15 wk of diabetes onset. At the end of studies, control USF2 (Tg) mice ( approximately 6 mo old) exhibited increased urinary albumin excretion. These mice also exhibited glomerular hypertrophy, accompanied by increased TSP1, active TGF-beta, fibronectin accumulation in the glomeruli compared with control WT littermates. Type 1 diabetes onset further augmented the urinary albumin excretion and glomerular hypertrophy in the USF2 (Tg) mice. These findings suggest that overexpression of USF2 accelerates the development of diabetic nephropathy.
