Transcriptional regulation of macrophage cholesterol efflux and atherogenesis by a long noncoding RNA
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE98910 | GEO | 2018/01/26
REPOSITORIES: GEO
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Project description:Nuclear receptors are important conduits between environmental cues and gene expression, but the molecular events governing spatial variation in their responses remain poorly understood. Here we outline an important role for a non-coding RNA in modulating the cell type-specific actions of the cholesterol-activated nuclear receptor LXR. LXR regulates the expression of genes involved in responses to excess cholesterol and has been causally linked to the pathogenesis and treatment of prevention and atherosclerosis in animals. We identify the lncRNA MeXis as an amplifier of LXR-dependent transcription of the critical cholesterol efflux gene Abca1. MeXis interacts with and guides the promoter binding of the nuclear receptor transcriptional coactivator DDX17. Loss of MeXis in murine immune cells has a marked impact on chromosome architecture at the Abca1 locus, impairs cellular responses to cholesterol overload, and accelerates the development of atherosclerosis. Our findings define MeXis as a lncRNA gatekeeper that modifies the actions of LXR in lipid-dependent control of macrophage gene expression. This has important implications for mechanisms that underlie spatial activation patterns of nuclear receptors. Our work opens a new gateway to targeting reverse cholesterol transport since it is conceivable that therapeutic approaches that enhance MeXis activity might reduce foam cell formation and atherogenesis.
2018-01-26 | GSE97207 | GEO
Project description:In this work we show that the LXR target lncRNA MeXis plays an important role in cellular responses to cholesterol overload In this experiment we use array technology to decipher the contribution of loss of MeXis from mouse primary peritoneal macrophages.
2018-01-26 | GSE107977 | GEO
Project description:Dysregulation of cholesterol metabolism and homeostasis is associated with the pathology of many diseases such as cardiovascular disease and cancer. Two major upstream regulators of cholesterol homeostasis are the SREBP2 pathway and the actions of the liver X receptors (LXRs), with the liver thought to handle the majority of cholesterol homeostasis at the organismal level. Endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC), which serve to activate the nuclear receptor LXR, result in increased expression of genes associated with cholesterol catabolism and efflux. LXR and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that similar to steroid nuclear receptors, the LXR may be selectively modulated by ligands. Here, we use bulk RNA-sequencing of bone marrow-derived macrophages and single-cell RNA-sequencing of immune cells from murine lungs bearing metastatic mammary cancer, to prove that LXR satisfies the two principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on cell or tissue type. The concept that the LXR can be selectively modulated provides the foundation for the development of ligands that are tailored to promote those activities that are desirable (pro-immune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).
2022-06-01 | GSE186909 | GEO
Project description:Dysregulation of cholesterol metabolism and homeostasis is associated with the pathology of many diseases such as cardiovascular disease and cancer. Two major upstream regulators of cholesterol homeostasis are the SREBP2 pathway and the actions of the liver X receptors (LXRs), with the liver thought to handle the majority of cholesterol homeostasis at the organismal level. Endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC), which serve to activate the nuclear receptor LXR, result in increased expression of genes associated with cholesterol catabolism and efflux. LXR and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that similar to steroid nuclear receptors, the LXR may be selectively modulated by ligands. Here, we use bulk RNA-sequencing of bone marrow-derived macrophages and single-cell RNA-sequencing of immune cells from murine lungs bearing metastatic mammary cancer, to prove that LXR satisfies the two principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on cell or tissue type. The concept that the LXR can be selectively modulated provides the foundation for the development of ligands that are tailored to promote those activities that are desirable (pro-immune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).
2022-06-01 | GSE186910 | 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: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 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:Efferocytosis is critical for tissue homeostasis, as its deregulation is associated with several autoimmune pathologies. While engulfing apoptotic cells, phagocytes activate transcription factors, such as peroxisome proliferator-activated receptors (PPAR) or liver X receptors (LXR) that orchestrate metabolic, phagocytic, and inflammatory responses towards the ingested material. Coordination of these transcription factors in efferocytotic human macrophages (MF) is not fully understood. In this study, we evaluated the transcriptional profile of MF following the uptake of apoptotic Jurkat T cells using RNA-seq analysis. Results indicated upregulation of PPAR and LXR pathways but downregulation of sterol regulatory element-binding proteins (SREBP) target genes. Pharmacological inhibition and RNA interference pointed to LXR and PPARdelta as relevant transcriptional regulators, while PPARdelta did not substantially contribute to gene regulation. Mechanistically, lysosomal digestion and lysosomal acid lipase (LIPA) were required for PPAR and LXR activation, while PPARdelta activation also demanded an active lysosomal phospholipase A2 (PLA2G15). Pharmacological interference with LXR signaling attenuated ABCA1-dependent cholesterol efflux from efferocytotic MF, but suppression of inflammatory responses following efferocytosis occurred independently of LXR and PPARdelta. These data provide mechanistic details on LXR and PPARdelta activation in efferocytotic human MF.
2021-05-26 | GSE169160 | GEO
Project description:Cholesterol biosynthetic intermediates such as lanosterol and desmosterol are emergent immune regulators of macrophages in response to inflammatory stimuli or lipid overloading, respectively. However, the participation of these sterols in regulating macrophage functions in the physiological context of atherosclerosis, an inflammatory disease driven by the accumulation of cholesterol-laden macrophages in the artery wall, has remained elusive. Here we report that desmosterol, the most abundant cholesterol biosynthetic intermediate in human coronary artery lesions, plays an essential role during atherogenesis, serving as a key molecule integrating cholesterol homeostasis and immune responses in macrophages. Depletion of desmosterol in myeloid cells by overexpression of 3β-hydroxysterol Δ24-reductase (DHCR24), the enzyme that catalyzes conversion of desmosterol to cholesterol, promotes the progression of atherosclerosis. Single cell transcriptomics in isolated CD45+CD11b+ cells from atherosclerotic plaques demonstrate that depletion of desmosterol increases interferon (IFN) responses and attenuates the expression of anti-inflammatory macrophage markers. Lipidomic and transcriptomic analysis of in vivo macrophage foam cells demonstrate that desmosterol is a major endogenous liver X receptor (LXR) ligand involved in LXR/RXR activation and thus, macrophage foam cell formation. Decreased desmosterol accumulation in mitochondria promotes macrophage mito-ROS production and NLRP3-dependent inflammasome activation. Deficiency of NLRP3 or ASC rescues the increased inflammasome activity and atherogenesis observed in desmosterol-depleted macrophages. Altogether, these findings underscore the critical function of desmosterol in the atherosclerotic plaque to dampen inflammation, by integrating with macrophage cholesterol metabolism and inflammatory activation, and protecting from disease progression.
2021-12-31 | GSE172374 | GEO
Project description:Cholesterol biosynthetic intermediates such as lanosterol and desmosterol are emergent immune regulators of macrophages in response to inflammatory stimuli or lipid overloading, respectively. However, the participation of these sterols in regulating macrophage functions in the physiological context of atherosclerosis, an inflammatory disease driven by the accumulation of cholesterol-laden macrophages in the artery wall, has remained elusive. Here we report that desmosterol, the most abundant cholesterol biosynthetic intermediate in human coronary artery lesions, plays an essential role during atherogenesis, serving as a key molecule integrating cholesterol homeostasis and immune responses in macrophages. Depletion of desmosterol in myeloid cells by overexpression of 3β-hydroxysterol Δ24-reductase (DHCR24), the enzyme that catalyzes conversion of desmosterol to cholesterol, promotes the progression of atherosclerosis. Single cell transcriptomics in isolated CD45+CD11b+ cells from atherosclerotic plaques demonstrate that depletion of desmosterol increases interferon (IFN) responses and attenuates the expression of anti-inflammatory macrophage markers. Lipidomic and transcriptomic analysis of in vivo macrophage foam cells demonstrate that desmosterol is a major endogenous liver X receptor (LXR) ligand involved in LXR/RXR activation and thus, macrophage foam cell formation. Decreased desmosterol accumulation in mitochondria promotes macrophage mito-ROS production and NLRP3-dependent inflammasome activation. Deficiency of NLRP3 or ASC rescues the increased inflammasome activity and atherogenesis observed in desmosterol-depleted macrophages. Altogether, these findings underscore the critical function of desmosterol in the atherosclerotic plaque to dampen inflammation, by integrating with macrophage cholesterol metabolism and inflammatory activation, and protecting from disease progression.
2021-12-01 | GSE175312 | GEO