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1.
EBioMedicine ; 18: 139-145, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28330813

RESUMO

Despite the recognized role of the ATP-binding Cassette Transporter A1 (ABCA1) in high-density lipoprotein (HDL) metabolism, our understanding of ABCA1 deficiency in human hepatocytes is limited. To define the functional effects of human hepatocyte ABCA1 deficiency, we generated induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (HLCs) from Tangier disease (TD) and matched control subjects. Control HLCs exhibited robust cholesterol efflux to apolipoprotein A-I (apoA-I) and formed nascent HDL particles. ABCA1-deficient HLCs failed to mediate lipid efflux or nascent HDL formation, but had elevated triglyceride (TG) secretion. Global transcriptome analysis revealed significantly increased ANGPTL3 expression in ABCA1-deficient HLCs. Angiopoietin-related protein 3 (ANGPTL3) was enriched in plasma of TD relative to control subjects. These results highlight the required role of ABCA1 in cholesterol efflux and nascent HDL formation by hepatocytes. Furthermore, our results suggest that hepatic ABCA1 deficiency results in increased hepatic TG and ANGPTL3 secretion, potentially underlying the elevated plasma TG levels in TD patients.


Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Lipoproteínas HDL/metabolismo , Transportador 1 de Cassete de Ligação de ATP/genética , Proteína 3 Semelhante a Angiopoietina , Proteínas Semelhantes a Angiopoietina/sangue , Proteínas Semelhantes a Angiopoietina/genética , Proteínas Semelhantes a Angiopoietina/metabolismo , Apolipoproteína A-I/metabolismo , Diferenciação Celular , Células Cultivadas , Colesterol/metabolismo , Hepatócitos/citologia , Hepatócitos/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Doença de Tangier/metabolismo , Doença de Tangier/patologia , Transcriptoma , Triglicerídeos/metabolismo
2.
Hum Mol Genet ; 24(6): 1801-12, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25416278

RESUMO

Fever predicts clinical outcomes in sepsis, trauma and during cardiovascular stress, yet the genetic determinants are poorly understood. We used an integrative genomics approach to identify novel genomic determinants of the febrile response to experimental endotoxemia. We highlight multiple integrated lines of evidence establishing the clinical relevance of this novel fever locus. Through genome-wide association study (GWAS) of evoked endotoxemia (lipopolysaccharide (LPS) 1 ng/kg IV) in healthy subjects of European ancestry we discovered a locus on chr7p11.2 significantly associated with the peak febrile response to LPS (top single nucleotide polymorphism (SNP) rs7805622, P = 2.4 × 10(-12)), as well as with temperature fluctuation over time. We replicated this association in a smaller independent LPS study (rs7805622, P = 0.03). In clinical translation, this locus was also associated with temperature and mortality in critically ill patients with trauma or severe sepsis. The top GWAS SNPs are not located within protein-coding genes, but have significant cis-expression quantitative trait loci (eQTL) associations with expression of a cluster of genes ∼400 kb upstream, several of which (SUMF2, CCT6A, GBAS) are regulated by LPS in vivo in blood cells. LPS- and cold-treatment of adipose stromal cells in vitro suggest genotype-specific modulation of eQTL candidate genes (PSPH). Several eQTL genes were up-regulated in brown and white adipose following cold exposure in mice, highlighting a potential role in thermogenesis. Thus, through genomic interrogation of experimental endotoxemia, we identified and replicated a novel fever locus on chr7p11.2 that modulates clinical responses in trauma and sepsis, and highlight integrated in vivo and in vitro evidence for possible novel cis candidate genes conserved across human and mouse.


Assuntos
Cromossomos Humanos Par 7 , Febre/genética , Loci Gênicos , Estresse Fisiológico/genética , Adolescente , Adulto , Idoso , Animais , Feminino , Febre/induzido quimicamente , Estudo de Associação Genômica Ampla , Humanos , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Elementos Reguladores de Transcrição , Sepse/genética , Estresse Fisiológico/efeitos dos fármacos , População Branca/genética , Ferimentos e Lesões/genética , Adulto Jovem
3.
J Am Coll Cardiol ; 59(8): 764-72, 2012 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-22340269

RESUMO

OBJECTIVES: This study sought to examine the role of lipoprotein-associated phospholipase A2 (Lp-PLA2/PLA2G7) in human inflammation and coronary atherosclerosis. BACKGROUND: Lp-PLA2 has emerged as a potential therapeutic target in coronary heart disease. Data supporting Lp-PLA2 are indirect and confounded by species differences; whether Lp-PLA2 is causal in coronary heart disease remains in question. METHODS: We examined inflammatory regulation of Lp-PLA2 during experimental endotoxemia in humans, probed the source of Lp-PLA2 in human leukocytes under inflammatory conditions, and assessed the relationship of variation in PLA2G7, the gene encoding Lp-PLA2, with coronary artery calcification. RESULTS: In contrast to circulating tumor necrosis factor-alpha and C-reactive protein, blood and monocyte Lp-PLA2 messenger ribonucleic acid decreased transiently, and plasma Lp-PLA2 mass declined modestly during endotoxemia. In vitro, Lp-PLA2 expression increased dramatically during human monocyte to macrophage differentiation and further in inflammatory macrophages and foamlike cells. Despite only a marginal association of single nucleotide polymorphisms in PLA2G7 with Lp-PLA2 activity or mass, numerous PLA2G7 single nucleotide polymorphisms were associated with coronary artery calcification. In contrast, several single nucleotide polymorphisms in CRP were significantly associated with plasma C-reactive protein levels but had no relation with coronary artery calcification. CONCLUSIONS: Circulating Lp-PLA2 did not increase during acute phase response in humans, whereas inflammatory macrophages and foam cells, but not circulating monocytes, are major leukocyte sources of Lp-PLA2. Common genetic variation in PLA2G7 is associated with subclinical coronary atherosclerosis. These data link Lp-PLA2 to atherosclerosis in humans while highlighting the challenge in using circulating Lp-PLA2 as a biomarker of Lp-PLA2 actions in the vasculature.


Assuntos
1-Alquil-2-acetilglicerofosfocolina Esterase/genética , Doença da Artéria Coronariana/genética , Regulação da Expressão Gênica , Inflamação/genética , RNA Mensageiro/genética , 1-Alquil-2-acetilglicerofosfocolina Esterase/metabolismo , Adulto , Biomarcadores/metabolismo , Doença da Artéria Coronariana/enzimologia , Doença da Artéria Coronariana/patologia , Feminino , Humanos , Inflamação/enzimologia , Masculino , Polimorfismo de Nucleotídeo Único , Reação em Cadeia da Polimerase em Tempo Real
4.
PLoS Genet ; 7(12): e1002393, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22174694

RESUMO

Genome-wide association studies (GWAS) have successfully identified loci associated with quantitative traits, such as blood lipids. Deep resequencing studies are being utilized to catalogue the allelic spectrum at GWAS loci. The goal of these studies is to identify causative variants and missing heritability, including heritability due to low frequency and rare alleles with large phenotypic impact. Whereas rare variant efforts have primarily focused on nonsynonymous coding variants, we hypothesized that noncoding variants in these loci are also functionally important. Using the HDL-C gene LIPG as an example, we explored the effect of regulatory variants identified through resequencing of subjects at HDL-C extremes on gene expression, protein levels, and phenotype. Resequencing a portion of the LIPG promoter and 5' UTR in human subjects with extreme HDL-C, we identified several rare variants in individuals from both extremes. Luciferase reporter assays were used to measure the effect of these rare variants on LIPG expression. Variants conferring opposing effects on gene expression were enriched in opposite extremes of the phenotypic distribution. Minor alleles of a common regulatory haplotype and noncoding GWAS SNPs were associated with reduced plasma levels of the LIPG gene product endothelial lipase (EL), consistent with its role in HDL-C catabolism. Additionally, we found that a common nonfunctional coding variant associated with HDL-C (rs2000813) is in linkage disequilibrium with a 5' UTR variant (rs34474737) that decreases LIPG promoter activity. We attribute the gene regulatory role of rs34474737 to the observed association of the coding variant with plasma EL levels and HDL-C. Taken together, the findings show that both rare and common noncoding regulatory variants are important contributors to the allelic spectrum in complex trait loci.


Assuntos
HDL-Colesterol/genética , HDL-Colesterol/metabolismo , Lipase/genética , Lipase/metabolismo , Metabolismo dos Lipídeos/genética , Regiões 5' não Traduzidas , Adulto , Idoso , Alelos , HDL-Colesterol/sangue , Feminino , Expressão Gênica , Frequência do Gene , Genes Reguladores/genética , Estudo de Associação Genômica Ampla , Genótipo , Haplótipos/genética , Sequenciamento de Nucleotídeos em Larga Escala , Células Endoteliais da Veia Umbilical Humana , Humanos , Lipase/sangue , Masculino , Pessoa de Meia-Idade , Mutagênese Sítio-Dirigida , Fenótipo , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas
5.
Circ Cardiovasc Genet ; 4(2): 145-55, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21303902

RESUMO

BACKGROUND: Plasma levels of high-density lipoprotein cholesterol (HDL-C) are known to be heritable, but only a fraction of the heritability is explained. We used a high-density genotyping array containing single-nucleotide polymorphisms (SNPs) from HDL-C candidate genes selected on known biology of HDL-C metabolism, mouse genetic studies, and human genetic association studies. SNP selection was based on tagging SNPs and included low-frequency nonsynonymous SNPs. METHODS AND RESULTS: Association analysis in a cohort containing extremes of HDL-C (case-control, n=1733) provided a discovery phase, with replication in 3 additional populations for a total meta-analysis in 7857 individuals. We replicated the majority of loci identified through genome-wide association studies and present on the array (including ABCA1, APOA1/C3/A4/A5, APOB, APOE/C1/C2, CETP, CTCF-PRMT8, FADS1/2/3, GALNT2, LCAT, LILRA3, LIPC, LIPG, LPL, LRP4, SCARB1, TRIB1, ZNF664) and provide evidence that suggests an association in several previously unreported candidate gene loci (including ABCG1, GPR109A/B/81, NFKB1, PON1/2/3/4). There was evidence for multiple, independent association signals in 5 loci, including association with low-frequency nonsynonymous variants. CONCLUSIONS: Genetic loci associated with HDL-C are likely to harbor multiple, independent causative variants, frequently with opposite effects on the HDL-C phenotype. Cohorts comprising subjects at the extremes of the HDL-C distribution may be efficiently used in a case-control discovery of quantitative traits.


Assuntos
HDL-Colesterol/genética , Loci Gênicos , Adulto , Idoso , Estudos de Casos e Controles , HDL-Colesterol/sangue , Estudos de Coortes , Dessaturase de Ácido Graxo Delta-5 , Feminino , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Polimorfismo de Nucleotídeo Único
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