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Early growth response 1 (Egr1) regulates cholesterol biosynthetic gene expression.

ABSTRACT: The early growth response (EGR) family of transcription factors has been implicated in control of lipid biosynthetic genes. Egr1 is induced by insulin both in vitro and in vivo and is the most highly expressed family member in liver. In this study, we investigated whether Egr1 regulates cholesterol biosynthetic genes in liver. Using an insulin-sensitive liver cell line, we show that localization of Egr1 to cholesterol biosynthetic genes is induced by insulin treatment and that this localization precedes the induction of the genes. Reduction in Egr1 expression using targeted siRNA blunted the insulin-dependent induction of cholesterol genes. A similar reduction in squalene epoxidase expression was also observed in Egr1 null mice. In addition, application of chromatin immunoprecipitation (ChIP) samples to tiled gene microarrays revealed localization of Egr1 in promoter regions of many cholesterol gene loci. In vivo ChIP assays using liver tissue show that Egr1 localization to several cholesterol biosynthetic gene promoters is induced by feeding. Finally, analysis of plasma cholesterol in Egr1(-/-) mice indicated a significant decrease in serum cholesterol when compared with wild-type mice. Together these data point to Egr1 as a modulator of the cholesterol biosynthetic gene family in liver.

SUBMITTER: Gokey NG

PROVIDER: S-EPMC3190990 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Early growth response 1 (Egr1) regulates cholesterol biosynthetic gene expression.

Gokey Nolan G NG Lopez-Anido Camila C Gillian-Daniel Anne Lynn AL Svaren John J

The Journal of biological chemistry 20110628 34

The early growth response (EGR) family of transcription factors has been implicated in control of lipid biosynthetic genes. Egr1 is induced by insulin both in vitro and in vivo and is the most highly expressed family member in liver. In this study, we investigated whether Egr1 regulates cholesterol biosynthetic genes in liver. Using an insulin-sensitive liver cell line, we show that localization of Egr1 to cholesterol biosynthetic genes is induced by insulin treatment and that this localization ...[more]

PMID: 21712389

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Project description:It is now clearly established that complex interactions between genes and environment are involved in multiple aspects of neuropsychiatric disorders, from determining an individual's vulnerability to onset, to influencing its response to therapeutic intervention. In this perspective, it appears crucial to better understand how the organism reacts to environmental stimuli and provide a coordinated and adapted response. In the central nervous system, neuronal plasticity and neurotransmission are among the major processes integrating such complex interactions between genes and environmental stimuli. In particular, immediate early genes (IEGs) are critical components of these interactions as they provide the molecular framework for a rapid and dynamic response to neuronal activity while opening the possibility for a lasting and sustained adaptation through regulation of the expression of a wide range of genes. As a result, IEGs have been tightly associated with neuronal activity as well as a variety of higher order processes within the central nervous system such as learning, memory and sensitivity to reward. The immediate early gene and transcription factor early growth response 1 (EGR1) has thus been revealed as a major mediator and regulator of synaptic plasticity and neuronal activity in both physiological and pathological conditions. In this review article, we will focus on the role of EGR1 in the central nervous system. First, we will summarize the different factors influencing its activity. Then, we will analyze the amount of data, including genome-wide, that has emerged in the recent years describing the wide variety of genes, pathways and biological functions regulated directly or indirectly by EGR1. We will thus be able to gain better insights into the mechanisms underlying EGR1's functions in physiological neuronal activity. Finally, we will discuss and illustrate the role of EGR1 in pathological states with a particular interest in cognitive functions and neuropsychiatric disorders.

Project description:BackgroundThe expression level of early growth response 1 (EGR1) is elevated in colon cancer (CC) tissues and is closely associated with poor prognosis in colorectal cancer. However, the role of EGR1 as a transcription factor (TF) influencing cell senescence in the progression of CC remains largely unexplored. This study aims to investigate the impact of curcumin on colorectal cancer cell senescence by modulating EGR1.MethodsGenes associated with cell senescence were obtained from a public database, and ChIP-X predicted TFs were utilized. The R2 database was employed to examine the relationship between gene expression and survival. CC cell lines were transfected with plasmids to achieve stable expression. Stable transfected cell lines were screened, and changes in RNA and protein expression were assessed using real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and Western blot (WB) analysis. Senescence levels were measured by SA-β-Gal staining. Cell proliferation and invasion capabilities were evaluated through soft agar and Matrigel invasion assays. Molecular docking was used to predict the interaction between curcumin and EGR1. Gene activity changes were detected using a dual luciferase reporter gene assay.ResultsThe results indicated that EGR1 was overexpressed in CC tissues and correlated with poor prognosis. As a TF, EGR1 negatively regulated the expression of telomerase reverse transcriptase (TERT) and sirtuin 6 (SIRT6) genes associated with cell senescence. Knocking down EGR1 increased the rate of cell senescence and inhibited cell proliferation and invasion. Curcumin inhibited the transcriptional activity of EGR1, thereby promoting cell senescence and inhibiting tumor progression.ConclusionsIn conclusion, curcumin hampers the activity of TF EGR1, affecting the transcription and translation of target genes TERT and SIRT6, thus promoting cell senescence and inhibiting CC cell proliferation. These findings provide potential insights for targeted therapy of CC.

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Early growth response 1 (Egr1) regulates cholesterol biosynthetic gene expression.

Publications

Early growth response 1 (Egr1) regulates cholesterol biosynthetic gene expression.

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