scholarly journals Analysis of the Glucose-Dependent Transcriptome in Murine Hypothalamic Cells

2021 ◽  
Author(s):  
Leonhard Webert ◽  
Dennis Faro ◽  
Sarah Zeitlmayr ◽  
Thomas Gudermann ◽  
Andreas Breit
Keyword(s):  
Protein Expression ◽  
Regulatory Element ◽  
Cholesterol Biosynthesis ◽  
Mrna Levels ◽  
Glucose Levels ◽  
Extracellular Glucose ◽  
Hypothalamic Cells ◽  
Functional Consequences ◽  
Reporter Assays ◽  
Sterol Regulatory Element

Abstract We have previously shown that glucose activates CREB-regulated transcriptional co-activator-2 (CRTC-2) in murine, hypothalamic (mHypoA-2/10) cells. Thus, we now analysed the entire glucose-dependent transcriptome of mHypoA-2/10 cells by total RNA-seq. 831 genes were up- and 1390 genes down-regulated by at least 50 %. Signalling pathway analysis revealed activation of the cholesterol biosynthesis pathway by glucose. Accordingly, protein expression of both sterol regulatory element-binding proteins (SREBP) and total cholesterol levels were enhanced by glucose. Analysis of single genes involved in fundamental signalling processes suggested a significant impact of glucose. Thus, we chose ~100 genes and validated the effects of glucose on mRNA levels by qRT-PCR. We identified 15 genes with strong glucose-dependent mRNA expression. Among these genes were gnai1 to -3, adyc6, irs1, igfr1, hras and elk3. cAMP measurements revealed decreased basal and enhanced noradrenalin-induced cAMP levels at higher glucose concentrations. Serum-response element-dependent reporter assays indicated enhanced basal and insulin-like growth factor-induced activity at higher glucose levels. siRNA against CRTC-2 dampened the effects of glucose on cholesterol synthesis and IRS-1, SREBP-1, SREBP-2 or AC-6 protein expression. These findings could help to understand the functional consequences of physiologically occurring alterations of extracellular glucose concentrations as well as pathologically increased glucose levels.

Curcumin Inhibits the Proteolytic Process of SREBP-2 by First Inhibiting the Expression of S1P rather than Directly Inhibiting SREBP-2 Expression.

2020 ◽  
Author(s):  
Yongnan Li ◽  
Shuodong Wu
Keyword(s):  
Transcription Factor ◽  
Protein Expression ◽  
Cholesterol Metabolism ◽  
Regulatory Element ◽  
Inhibitory Effect ◽  
Specific Protein ◽  
Mrna Levels ◽  
Curcumin Treatment ◽  
Short Period ◽  
Sterol Regulatory Element

Abstract Objective: Many studies have demonstrated that curcumin can downregulate mRNA levels of sterol regulatory element-binding proteins (SREBP-2), however, our study did not find similar results. This study was designed to demonstrate that curcumin inhibits the proteolytic process of SREBP-2 by first inhibiting the expression of membrane-bound transcription factor site-1 protease (S1P) rather than directly inhibiting SREBP-2 expression.Methods: After curcumin treatment, Caco-2 cells were collected to observe the dose- and time-dependent dynamics of precursor and mature SREBP-2, transcription factor specific protein 1 (SP-1) and SREBP cleavage-activating protein (SCAP). After curcumin treatment, SREBP-2 distribution was detected in the cells and S1P protein expression were examined.Results: Curcumin could downregulate mRNA levels of SREBP2, SP-1 and SCAP, but it did not simultaneously downregulate the expression of precursor SREBP-2 (pSREBP-2) and SCAP. Curcumin can inhibit the proteolytic process of SREBP-2, reduce the production of mature SREBP-2 (mSREBP-2) and change the cellular distribution of SREBP-2. The inhibitory effect of curcumin on SP-1 protein expression is short-acting. Conclusion: Curcumin can inhibit the SREBP-2 proteolytic process to reduce mSREBP-2 which functions as a transcription factor, affecting the regulation of cholesterol metabolism-related genes. This process may be achieved by regulating the expression of S1P. Curcumin does not directly inhibit the expression of mSREBP-2 protein, and it has no such inhibitory effect for at least a short period of time, although curcumin does reduce the amount of mSREBP-2 protein.

scholarly journals Central Leptin Regulates Total Ceramide Content and Sterol Regulatory Element Binding Protein-1C Proteolytic Maturation in Rat White Adipose Tissue

Endocrinology ◽  
2008 ◽  
Vol 150 (1) ◽  
pp. 169-178 ◽  
Author(s):  
Elena Bonzón-Kulichenko ◽  
Dominik Schwudke ◽  
Nilda Gallardo ◽  
Eduardo Moltó ◽  
Teresa Fernández-Agulló ◽  
...  
Keyword(s):  
Nervous System ◽  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
White Adipose Tissue ◽  
Binding Protein ◽  
Regulatory Element ◽  
Mrna Levels ◽  
Element Binding Protein ◽  
Ceramide Content ◽  
Sterol Regulatory Element

Obesity and type 2 diabetes are associated with insulin and leptin resistance, and increased ceramide contents in target tissues. Because the adipose tissue has become a central focus in these diseases, and leptin-induced increases in insulin sensitivity may be related to effects of leptin on lipid metabolism, we investigated herein whether central leptin was able to regulate total ceramide levels and the expression of enzymes involved in ceramide metabolism in rat white adipose tissue (WAT). After 7 d central leptin treatment, the total content of ceramides was analyzed by quantitative shotgun lipidomics mass spectrometry. The effects of leptin on the expression of several enzymes of the sphingolipid metabolism, sterol regulatory element binding protein (SREBP)-1c, and insulin-induced gene 1 (INSIG-1) in this tissue were studied. Total ceramide levels were also determined after surgical WAT denervation. Central leptin infusion significantly decreased both total ceramide content and the long-chain fatty acid ceramide species in WAT. Concomitant with these results, leptin decreased the mRNA levels of enzymes involved in de novo ceramide synthesis (SPT-1, LASS2, LASS4) and ceramide production from sphingomyelin (SMPD-1/2). The mRNA levels of enzymes of ceramide degradation (Asah1/2) and utilization (sphingomyelin synthase, ceramide kinase, glycosyl-ceramide synthase, GM3 synthase) were also down-regulated. Ceramide-lowering effects of central leptin were prevented by local autonomic nervous system denervation of WAT. Finally, central leptin treatment markedly increased INSIG-1 mRNA expression and impaired SREBP-1c activation in epididymal WAT. These observations indicate that in vivo central leptin, acting through the autonomic nervous system, regulates total ceramide levels and SREBP-1c proteolytic maturation in WAT, probably contributing to improve the overall insulin sensitivity. Central leptin decreases total ceramide levels and prevents sterol regulatory element binding protein (SREBP-1C) proteolytic maturation in white adipose tissue, and probably, in this way, contributes to improve the overall insulin sensitivity.

scholarly journals A simple promoter containing two Sp1 sites controls the expression of sterol-regulatory-element-binding protein 1a (SREBP-1a)

2005 ◽  
Vol 386 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Chengkang ZHANG ◽  
Dong-Ju SHIN ◽  
Timothy F. OSBORNE
Keyword(s):  
Transcriptional Activation ◽  
Binding Protein ◽  
Regulatory Element ◽  
Animal Experiments ◽  
Proximal Region ◽  
Mrna Levels ◽  
Relative Level ◽  
Transcriptional Activation Domain ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

The mammalian gene for SREBP-1 (sterol-regulatory-element-binding protein 1) contains two promoters that control the production of two proteins, SREBP-1a and -1c, and each contains a unique N-terminal transcriptional activation domain, but they are otherwise identical. The relative level of each mRNA varies from tissue to tissue and they respond differently to regulatory stimuli. SREBP-1c is more abundantly expressed in liver, where its level is also regulated by insulin and liver X receptor activators, and it is also autoregulated by SREBPs. In contrast, SREBP-1a mRNA levels are relatively low and constant in different tissues and few studies have specifically analysed its pattern of expression and regulation. In the present study, we show that the promoter for SREBP-1a is contained in a very small promoter-proximal region containing two Sp1 sites. The small and relatively simple structure for its promoter provides an explanation for the low level of SREBP-1a expression. Additionally, since Sp1 has been implicated in the modest regulation of several genes by insulin, its involvement in the expression of the SREBP-1a promoter provides an explanation for the modest insulin regulation observed in animal experiments.

scholarly journals Wnt signaling mediates oncogenic synergy between Akt and Dlx5 in T-cell lymphomagenesis by enhancing cholesterol synthesis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yinfei Tan ◽  
Eleonora Sementino ◽  
Zemin Liu ◽  
Kathy Q. Cai ◽  
Joseph R. Testa
Keyword(s):  
Transcription Factor ◽  
T Cell ◽  
Cholesterol Synthesis ◽  
Regulatory Element ◽  
Cholesterol Biosynthesis ◽  
Homeobox Gene ◽  
Rna Seq ◽  
Expression Of Genes ◽  
Highly Sensitive ◽  
Sterol Regulatory Element

Abstract The Dlx5 homeobox gene was first implicated as an oncogene in a T-ALL mouse model expressing myristoylated (Myr) Akt2. Furthermore, overexpression of Dlx5 was sufficient to drive T-ALL in mice by directly activating Akt and Notch signaling. These findings implied that Akt2 cooperates with Dlx5 in T-cell lymphomagenesis. To test this hypothesis, Lck-Dlx5;Lck-MyrAkt2 transgenic mice were generated. MyrAkt2 synergized with Dlx5 to greatly accelerate and enhance the dissemination of T-lymphomagenesis. RNA-seq analysis performed on lymphomas from Lck-Dlx5;Lck-MyrAkt mice revealed upregulation of genes involved in the Wnt and cholesterol biosynthesis pathways. Combined RNA-seq and ChIP-seq analysis of lymphomas from Lck-Dlx5;Lck-MyrAkt mice demonstrated that β-catenin directly regulates genes involved in sterol regulatory element binding transcription factor 2 (Srebf2)-cholesterol synthesis. These lymphoma cells had high Lef1 levels and were highly sensitive to β-catenin and Srebf2-cholesterol synthesis inhibitors. Similarly, human T-ALL cell lines with activated NOTCH and AKT and elevated LEF1 levels were sensitive to inhibition of β-catenin and cholesterol pathways. Furthermore, LEF1 expression positively correlated with expression of genes involved in the cholesterol synthesis pathway in primary human T-ALL specimens. Together, these data suggest that targeting β-catenin and/or cholesterol biosynthesis, together with AKT, could have therapeutic efficacy in a subset of T-ALL patients.

Effects of gender and GH secretory pattern on sterol regulatory element-binding protein-1c and its target genes in rat liver

2004 ◽  
Vol 287 (6) ◽  
pp. E1039-E1048 ◽  
Author(s):  
Caroline Améen ◽  
Daniel Lindén ◽  
Britt-Mari Larsson ◽  
Agneta Mode ◽  
Agneta Holmäng ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Continuous Infusion ◽  
Target Genes ◽  
Binding Protein ◽  
Regulatory Element ◽  
Female Rats ◽  
Mrna Levels ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Secretory Pattern

We investigated whether the sexually dimorphic secretory pattern of growth hormone (GH) in the rat regulates hepatic gene expression of sterol regulatory element-binding protein-1c (SREBP-1c) and its target genes. SREBP-1c, fatty acid synthase (FAS), and glycerol-3-phosphate acyltransferase (GPAT) mRNA were more abundant in female than in male livers, whereas acetyl-CoA carboxylase-1 (ACC1) and stearoyl-CoA desaturase-1 (SCD-1) were similarly expressed in both sexes. Hypophysectomized female rats were given GH as a continuous infusion or as two daily injections for 7 days to mimic the female- and male-specific GH secretory patterns, respectively. The female pattern of GH administration increased the expression of SREBP-1c, ACC1, FAS, SCD-1, and GPAT mRNA, whereas the male pattern of GH administration increased only SCD-1 mRNA. FAS and SCD-1 protein levels were regulated in a similar manner by GH. Incubation of primary rat hepatocytes with GH increased SCD-1 mRNA levels and decreased FAS and GPAT mRNA levels but had no effect on SREBP-1c mRNA. GH decreased hepatic liver X receptor-α (LXRα) mRNA levels both in vivo and in vitro. Feminization of the GH plasma pattern in male rats by administration of GH as a continuous infusion decreased insulin sensitivity and increased expression of FAS and GPAT mRNA but had no effect on SREBP-1c, ACC1, SCD-1, or LXRα mRNA. In conclusion, FAS and GPAT are specifically upregulated by the female secretory pattern of GH. This regulation is not a direct effect of GH on hepatocytes and does not involve changed expression of SREBP-1c or LXRα mRNA but is associated with decreased insulin sensitivity.

scholarly journals Sterol regulatory element binding protein and dietary lipid regulation of fatty acid synthesis in the mammary epithelium

2010 ◽  
Vol 299 (6) ◽  
pp. E918-E927 ◽  
Author(s):  
Michael C. Rudolph ◽  
Jenifer Monks ◽  
Valerie Burns ◽  
Meridee Phistry ◽  
Russell Marians ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
De Novo ◽  
Regulatory Element ◽  
Acid Synthesis ◽  
De Novo Lipogenesis ◽  
Mrna Levels ◽  
Sterol Regulatory Element

The lactating mammary gland synthesizes large amounts of triglyceride from fatty acids derived from the blood and from de novo lipogenesis. The latter is significantly increased at parturition and decreased when additional dietary fatty acids become available. To begin to understand the molecular regulation of de novo lipogenesis, we tested the hypothesis that the transcription factor sterol regulatory element binding factor (SREBF)-1c is a primary regulator of this system. Expression of Srebf1c mRNA and six of its known target genes increased ≥2.5-fold at parturition. However, Srebf1c-null mice showed only minor deficiencies in lipid synthesis during lactation, possibly due to compensation by Srebf1a expression. To abrogate the function of both isoforms of Srebf1, we bred mice to obtain a mammary epithelial cell-specific deletion of SREBF cleavage-activating protein (SCAP), the SREBF escort protein. These dams showed a significant lactation deficiency, and expression of mRNA for fatty acid synthase ( Fasn), insulin-induced gene 1 ( Insig1), mitochondrial citrate transporter ( Slc25a1), and stearoyl-CoA desaturase 2 ( Scd2) was reduced threefold or more; however, the mRNA levels of acetyl-CoA carboxylase-1α ( Acaca) and ATP citrate lyase ( Acly) were unchanged. Furthermore, a 46% fat diet significantly decreased de novo fatty acid synthesis and reduced the protein levels of ACACA, ACLY, and FASN significantly, with no change in their mRNA levels. These data lead us to conclude that two modes of regulation exist to control fatty acid synthesis in the mammary gland of the lactating mouse: the well-known SREBF1 system and a novel mechanism that acts at the posttranscriptional level in the presence of SCAP deletion and high-fat feeding to alter enzyme protein.

Increased hepatic lipogenesis in insulin resistance and Type 2 diabetes is associated with AMPK signalling pathway up-regulation in Psammomys obesus

2009 ◽  
Vol 29 (5) ◽  
pp. 283-292 ◽  
Author(s):  
Ali Ben Djoudi Ouadda ◽  
Emile Levy ◽  
Ehud Ziv ◽  
Geneviève Lalonde ◽  
Alain T. Sané ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Protein Expression ◽  
Body Weight Gain ◽  
Binding Protein ◽  
Regulatory Element ◽  
Mrna Levels ◽  
Psammomys Obesus ◽  
Element Binding Protein

AMPK (AMP-activated protein kinase) has been suggested to be a central player regulating FA (fatty acid) metabolism through its ability to regulate ACC (acetyl-CoA carboxylase) activity. Nevertheless, its involvement in insulin resistance- and TD2 (Type 2 diabetes)-associated dyslipidaemia remains enigmatic. In the present study, we employed the Psammomys obesus gerbil, a well-established model of insulin resistance and TD2, in order to appreciate the contribution of the AMPK/ACC pathway to the abnormal hepatic lipid synthesis and increased lipid accumulation in the liver. Our investigation provided evidence that the development of insulin resistance/diabetic state in P. obesus is accompanied by (i) body weight gain and hyperlipidaemia; (ii) elevations of hepatic ACC-Ser79 phosphorylation and ACC protein levels; (iii) a rise in the gene expression of cytosolic ACC1 concomitant with invariable mitochondrial ACC2; (iv) an increase in hepatic AMPKα-Thr172 phosphorylation and protein expression without any modification in the calculated ratio of phospho-AMPKα to total AMPKα; (v) a stimulation in ACC activity despite increased AMPKα phosphorylation and protein expression; and (vi) a trend of increase in mRNA levels of key lipogenic enzymes [SCD-1 (stearoyl-CoA desaturase-1), mGPAT (mitochondrial isoform of glycerol-3-phosphate acyltransferase) and FAS (FA synthase)] and transcription factors [SREBP-1 (sterol-regulatory-element-binding protein-1) and ChREBP (carbohydrate responsive element-binding protein)]. Altogether, our findings suggest that up-regulation of the AMPK pathway seems to be a natural response in order to reduce lipid metabolism abnormalities, thus supporting the role of AMPK as a promising target for the treatment of TD2-associated dyslipidaemia.

Acetyl-coenzyme A synthetase is a lipogenic enzyme controlled by SREBP-1 and energy status

2002 ◽  
Vol 282 (1) ◽  
pp. E222-E230 ◽  
Author(s):  
Hirohito Sone ◽  
Hitoshi Shimano ◽  
Yuki Sakakura ◽  
Noriyuki Inoue ◽  
Michiyo Amemiya-Kudo ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Coenzyme A ◽  
Regulatory Element ◽  
Luciferase Reporter ◽  
Mrna Levels ◽  
Lipogenic Enzyme ◽  
Acetyl Coenzyme A ◽  
Dietary Regulation ◽  
Acetyl Coenzyme ◽  
Sterol Regulatory Element

DNA microarray analysis on upregulated genes in the livers from transgenic mice overexpressing nuclear sterol regulatory element-binding protein (SREBP)-1a, identified an espressed sequence tag (EST) encoding a part of murine cytosolic acetyl-coenzyme A synthetase (ACAS). Northern blot analysis of the livers from transgenic mice demonstrated that this gene was highly induced by SREBP-1a, SREBP-1c, and SREBP-2. DNA sequencing of the 5′ flanking region of the murine ACAS gene identified a sterol regulatory element with an adjacent Sp1 site. This region was shown to be responsible for SREBP binding and activation of the ACAS gene by gel shift and luciferase reporter gene assays. Hepatic and adipose tissue ACAS mRNA levels in normal mice were suppressed at fasting and markedly induced by refeeding, and this dietary regulation was nearly abolished in SREBP-1 knockout mice, suggesting that the nutritional regulation of the ACAS gene is controlled by SREBP-1. The ACAS gene was downregulated in streptozotocin-induced diabetic mice and was restored after insulin replacement, suggesting that diabetic status and insulin also regulate this gene. When acetate was administered, hepatic ACAS mRNA was negatively regulated. These data on dietary regulation and SREBP-1 control of ACAS gene expression demonstrate that ACAS is a novel hepatic lipogenic enzyme, providing further evidence that SREBP-1 and insulin control the supply of acetyl-CoA directly from cellular acetate for lipogenesis. However, its high conservation among different species and the wide range of its tissue distribution suggest that this enzyme might also play an important role in basic cellular energy metabolism.

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