Pharmacological Targeting of a Metabolic Co-Dependency Pathway in Brain Cancers
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE78703 | GEO | 2017/09/08
SECONDARY ACCESSION(S): PRJNA313262
REPOSITORIES: GEO
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Project description:Liver X receptors (LXRs) are important regulators of cholesterol, lipid and glucose metabolism and have been extensively studied in liver, macrophages and adipose tissue. However, their role in skeletal muscle is not yet fully elucidated and the functional role of each of the LXRα and LXRβ subtypes in skeletal muscle is at present unknown. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRα and LXRβ knockout (KO) mice were established. The present study shows that treatment with the unselective LXR agonist T0901317 increased mRNA levels of LXR target genes such as sterol regulatory element-binding transcription factor 1 (SREBF1), fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1) and ATP-binding cassette transporter A1 (ABCA1) in myotubes established from WT and LXRα KO mice. However, only minor changes in expression level were observed for these genes after treatment with T0901317 in myotubes from LXRβ KO mice. Gene expression analysis using Affymetrix NuGO Genechip arrays showed that few other genes than the classical, well known LXR target genes were regulated by LXR in skeletal muscle. Furthermore, functional studies using radiolabeled substrates showed that treatment with T0901317 increased lipogenesis and apoA1 dependent cholesterol efflux, in myotubes from WT and LXRα KO mice, but not LXRβ KO mice. The data suggest that the lipogenic effects of LXRs, as well as the LXR-stimulated cholesterol efflux, are mainly mediated by LXRβ in skeletal muscle.
2010-03-31 | GSE13192 | GEO
Project description:The LXR proteins, LXRα and LXRβ, are transcription factors that belong to the nuclear receptor superfamily. LXRs are activated by oxysterols and control the transcription of genes involved in the regulation of cholesterol and fatty acid metabolism. They also mediate several aspects of macrophage biology, including inflammatory responses, cell survival in response to infection and phagocytosis of apoptotic cells. LXRs share a high degree of sequence homology and most of their functions are believed to be performed similarly by LXRα and LXRβ. However, the individual, transcriptional roles of each LXR isoform have not been characterized in detail, in part due to the lack of specific experimental tools that can discriminate between LXRα and LXRβ actions. To identify common and differential transcriptional functions of LXR nuclear receptors in macrophages, we developed a cellular model of stable expression of FLAG-tagged LXRα or LXRβ in LXR-null immortalized murine bone marrow-derived macrophages (parental line published Elife. 2015 Jul 14;4:e08009. doi: 10.7554/eLife.08009). To take a deeper insight into the epigenomic features of LXR nuclear receptors, we performed chromatin immunoprecipitation coupled to next-generation sequencing (ChIP-seq) to identify genome-wide binding locations of LXRα and LXRβ in the presence of a synthetic agonist (GW3965, 1uM). Additionally, we identified genome-wide DNA locations of acetylation mark on lysine 27 of histone H3 (H3K27ac), upon LXR agonist (GW3965, 1uM) and antagonist (GW2033, 1uM) treatment. Collectively, these studies will increase our understanding of common and differential genomic actions of LXRα and LXRβ in cultured murine macrophages.
2017-10-19 | GSE104027 | GEO
Project description:Liver X receptor (LXR) is a critical regulator of cholesterol homeostasis, and inhibits TCR-induced proliferation by altering intracellular sterol metabolism. However, the mechanisms by which LXR regulates helper T cell subset differentiation in vivo remains unclear. Here we demonstrate here that LXR is a crucial regulator of follicular helper T (Tfh) cells in vivo. Both mixed bone marrow chimera and antigen-specific T cell adoptive co-transfer studies show a specific increase in Tfh cells among LXRβ-deficient CD4+ T cell population in response to immunization and LCMV infection. Mechanistically LXRβ-deficient Tfh cells express increased levels of TCF-1 but comparable levels of Bcl6, CXCR5, and PD-1 in comparison with LXRβ-sufficient Tfh cells. Loss of LXRβ confers inactivation of GSK3β induced by either AKT/ERK activation or Wnt/β-catenin pathway, leading to elevated TCF-1 expression in CD4+ T cells. Conversely, ligation of LXR represses TCF-1 expression and Tfh cell differentiation in both murine and human CD4+ T cells. Treatment with an LXR agonist significantly diminishes Tfh cells and the levels of antigen-specific IgG upon immunization. These findings unveil a novel cell-intrinsic regulatory function of LXR in Tfh cell differentiation via controlling GSK3β-TCF1 pathway, which might be a promising target for pharmacological intervention in Tfh-mediated diseases.
2023-02-06 | GSE224303 | GEO
Project description:We profiled differential gene expression in vivo between pregnant day 14 (secretory differentiation) and lactation day 4 (established secretory activation) using isolated mouse mammary epithelial cells depleted of the mammary adipocytes. Liver-X-Receptors are ligand-dependent transcription factors activated by cholesterol metabolites. These receptors induce a suite of target genes required for de novo synthesis of triglycerides and cholesterol transport in many tissues. Two different isoforms -LXRα and LXRβ- have been well characterized in liver, adipocytes, macrophages and intestinal epithelium among others, but their contribution to cholesterol and fatty acid efflux in the lactating mammary gland is poorly understood. We hypothesize that LXR regulates lipogenesis during milk fat production in lactation. Global mRNA analysis of mouse mammary epithelial cells (MECs) revealed multiple LXR/RXR targets are upregulated sharply at the onset of lactation compared to mid-pregnancy. LXRα is the primary isoform and its protein levels increase throughout lactation in MECs. The LXR agonist GW3965 markedly induced several genes involved in cholesterol transport and lipogenesis and enhanced cytoplasmic lipid droplet accumulation in the HC11 MEC cell line. Importantly, in vivo pharmacological activation of LXR increased the milk cholesterol percentage and induced Srebp1c and Abca7 expression in MECs. Cumulatively, our findings identify LXRα as an important regulator of cholesterol incorporation into the milk through key nodes of de novo lipogenesis, suggesting a potential therapeutic target in women with difficulty initiating lactation.
2019-03-05 | GSE121819 | GEO
Project description:Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive hematological. We used transcriptomic analysis to investigate LXR pathway, and cholesterol metabolism in leukemic cells. Malignancy with a poor prognosis that derives from plasmacytoid dendritic cells (PDC). No consensus for optimal treatment modalities is available today and the full characterization of this leukemia is still emerging. We identified here a BPDCN-specific transcriptomic profile when compared to those of acute myeloid leukemia (AML) and T-acute lymphoblastic leukemia (T-ALL), as well as the transcriptomic signature of primary PDC. This BPDCN gene signature identified a dysregulation of genes involved in cholesterol homeostasis, some of them being liver X receptor (LXR) target genes. LXR agonist treatment of primary BPDCN cells and BPDCN cell lines restored LXR target gene expression and increased cholesterol efflux via the upregulation of ATP Binding Cassette (ABC) transporters, ABCA1 and ABCG1. LXR agonist treatment was responsible for limiting BPDCN cell proliferation and inducing intrinsic apoptotic cell death. LXR activation in BPDCN cells was shown to interfere with three signaling pathways associated with leukemic cell survival, namely: NF-κB activation, as well as Akt and STAT5 phosphorylation in response to the BPDCN growth/survival factor IL-3. These effects were increased by the stimulation of cholesterol efflux through a lipid acceptor, the apolipoprotein A1. In vivo experiments using a mouse model of BPDCN cell xenograft revealed a decrease of leukemic cell infiltration and BPDCN-induced cytopenia associated with an increased survival after LXR agonist treatment. This demonstrates that cholesterol homeostasis is modified in BPDCN and can be normalized by treatment with LXR agonists which can be proposed as a new therapeutic approach.
2017-02-10 | GSE89565 | GEO
Project description:Liver X receptors (LXRs) are important regulators of cholesterol, lipid and glucose metabolism and have been extensively studied in liver, macrophages and adipose tissue. However, their role in skeletal muscle is not yet fully elucidated and the functional role of each of the LXRM-NM-1 and LXRM-NM-2 subtypes in skeletal muscle is at present unknown. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRM-NM-1 and LXRM-NM-2 knockout (KO) mice were established. The present study shows that treatment with the unselective LXR agonist T0901317 increased mRNA levels of LXR target genes such as sterol regulatory element-binding transcription factor 1 (SREBF1), fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1) and ATP-binding cassette transporter A1 (ABCA1) in myotubes established from WT and LXRM-NM-1 KO mice. However, only minor changes in expression level were observed for these genes after treatment with T0901317 in myotubes from LXRM-NM-2 KO mice. Gene expression analysis using Affymetrix NuGO Genechip arrays showed that few other genes than the classical, well known LXR target genes were regulated by LXR in skeletal muscle. Furthermore, functional studies using radiolabeled substrates showed that treatment with T0901317 increased lipogenesis and apoA1 dependent cholesterol efflux, in myotubes from WT and LXRM-NM-1 KO mice, but not LXRM-NM-2 KO mice. The data suggest that the lipogenic effects of LXRs, as well as the LXR-stimulated cholesterol efflux, are mainly mediated by LXRM-NM-2 in skeletal muscle. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRa and LXRb knockout (KO) mice were established. Sixteen samples were examined. Half the samples were treated with the unselective LXR agonist T0901317.
2010-03-30 | E-GEOD-13192 | biostudies-arrayexpress
Project description:The activation of Liver X Receptor (LXR) promotes cholesterol efflux and repression of inflammatory genes with anti-atherogenic consequences. The mechanisms underlying repressive activity of LXR are controversial and have been attributed to cholesterol efflux or to transrepression of Activator Protein-1 (AP-1) activity. Here, we find that cholesterol efflux contributes to LXR repression, while direct repressive functions of LXR also play a key role but are independent of AP-1. We use ATAC-seq to show that LXR reduces chromatin accessibility in cis at inflammatory gene enhancers containing LXR binding sites. Targets of this repressive activity are associated with leukocyte adhesion and neutrophil migration, and LXR agonist treatment suppresses neutrophil recruitment in a mouse model of sterile peritonitis. These studies suggest a model of repression in which liganded LXR binds in cis to canonical nuclear receptor binding sites and represses pro-atherogenic leukocyte functions in tandem with induction of LXR targets mediating cholesterol efflux.
2018-11-17 | GSE109997 | GEO
Project description:The activation of Liver X Receptor (LXR) promotes cholesterol efflux and repression of inflammatory genes with anti-atherogenic consequences. The mechanisms underlying repressive activity of LXR are controversial and have been attributed to cholesterol efflux or to transrepression of Activator Protein-1 (AP-1) activity. Here, we find that cholesterol efflux contributes to LXR repression, while direct repressive functions of LXR also play a key role but are independent of AP-1. We use ATAC-seq to show that LXR reduces chromatin accessibility in cis at inflammatory gene enhancers containing LXR binding sites. Targets of this repressive activity are associated with leukocyte adhesion and neutrophil migration, and LXR agonist treatment suppresses neutrophil recruitment in a mouse model of sterile peritonitis. These studies suggest a model of repression in which liganded LXR binds in cis to canonical nuclear receptor binding sites and represses pro-atherogenic leukocyte functions in tandem with induction of LXR targets mediating cholesterol efflux.
2018-11-17 | GSE109998 | GEO
Project description:Liver X receptors (LXRs) are important regulators of cholesterol, lipid and glucose metabolism and have been extensively studied in liver, macrophages and adipose tissue. However, their role in skeletal muscle is not yet fully elucidated and the functional role of each of the LXRalpha (NR1H3) and LXRbeta (NR1H2) subtypes in skeletal muscle is at present unknown. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRalpha and LXRbeta knockout (KO) mice were established. The present study shows that treatment with the unselective LXR agonist T0901317 increased mRNA levels of LXR target genes such as sterol regulatory element-binding transcription factor 1 (SREBF1), fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1) and ATP-binding cassette transporter A1 (ABCA1) in myotubes established from WT and LXRalpha KO mice. However, only minor changes in expression level were observed for these genes after treatment with T0901317 in myotubes from LXRbeta KO mice. Gene expression analysis using Affymetrix NuGO Genechip arrays showed that few other genes than the classical, well known LXR target genes were regulated by LXR in skeletal muscle. Furthermore, functional studies using radiolabeled substrates showed that treatment with T0901317 increased lipogenesis and apoA1 dependent cholesterol efflux, in myotubes from WT and LXRalpha KO mice, but not LXRbeta KO mice. The data suggest that the lipogenic effects of LXRs, as well as the LXR-stimulated cholesterol efflux, are mainly mediated by LXRbeta in skeletal muscle.
2009-10-01 | E-MTAB-61 | biostudies-arrayexpress
Project description:The liver X receptors (LXRs) are nuclear receptors that form permissive heterodimers with retinoid X receptor (RXR) and are important regulators of lipid metabolism in the liver. We have recently shown that RXR agonist-induced hypertriglyceridemia and hepatic steatosis in mice is dependent on LXR and correlates with an LXR-dependent hepatic induction of lipogenic genes. To further investigate the role of RXR and LXR in the regulation of hepatic gene expression, we have mapped the ligand-regulated genome-wide binding of these factors in mouse liver. We find that the RXR agonist bexarotene primarily increases the genomic binding of RXR, whereas the LXR agonist T0901317 greatly increases both LXR and RXR binding. Functional annotation of putative direct LXR target genes revealed a significant association with classical LXR-regulated pathways as well as PPAR signaling pathways, and subsequent ChIP-seq mapping of PPARM-NM-1 binding demonstrated binding of PPARM-NM-1 to 71-88% of the identified LXR:RXR binding sites. Sequence analysis of shared binding regions combined with sequential ChIP on selected sites indicate that LXR:RXR and PPARM-NM-1:RXR bind to degenerate response elements in a mutually exclusive manner. Together our findings suggest extensive and unexpected cross-talk between hepatic LXR and PPARM-NM-1 at the level of binding to shared genomic sites LXR, RXR, PPARalpha and RNA Polymerase II ChIP-seq on livers from female C57BL/6 wild-type and/or LXRM-NM-1/M-NM-2-deficient mice (13 weeks of age, n=1) treated by oral gavage once daily for 14 days with the RXR agonist bexarotene (100 mg/kg body weight [mpk], in 1% carboxymethylcellulose), the LXR agonist T0901317 (T09, 30 mpk) or vehicle alone.
2012-01-31 | E-GEOD-35262 | biostudies-arrayexpress