title: Genetic and environmental risk factors for atherosclerosis regulate transcription of phosphatase and actin regulating gene PHACTR1.
abstract: Coronary artery disease (CAD) risk is associated with non-coding genetic variants at the phosphatase and actin regulating protein 1(PHACTR1) gene locus. The PHACTR1 gene encodes an actin-binding protein with phosphatase regulating activity. The mechanism whereby PHACTR1 influences CAD risk is unknown. We hypothesized that PHACTR1 would be expressed in human cell types relevant to CAD and regulated by atherogenic or genetic factors.
  
  
  
  Using immunohistochemistry, we demonstrate that PHACTR1 protein is expressed strongly in human atherosclerotic plaque macrophages, lipid-laden foam cells, adventitial lymphocytes and endothelial cells. Using a combination of genomic analysis and molecular techniques, we demonstrate that PHACTR1 is expressed as multiple previously uncharacterized transcripts in macrophages, foam cells, lymphocytes and endothelial cells. Immunoblotting confirmed a total absence of PHACTR1 in vascular smooth muscle cells. Real-time quantitative PCR showed that PHACTR1 is regulated by atherogenic and inflammatory stimuli. In aortic endothelial cells, oxLDL and TNF-alpha both upregulated an intermediate length transcript. A short transcript expressed only in immune cells was upregulated in macrophages by oxidized low-density lipoprotein, and oxidized phospholipids but suppressed by lipopolysaccharide or TNF-alpha. In primary human macrophages, we identified a novel expression quantitative trait locus (eQTL) specific for this short transcript, whereby the risk allele at CAD risk SNP rs9349379 is associated with reduced PHACTR1 expression, similar to the effect of an inflammatory stimulus.
  
  
  
  Our data demonstrate that PHACTR1 is a key atherosclerosis candidate gene since it is regulated by atherogenic stimuli in macrophages and endothelial cells and we identify an effect of the genetic risk variant on PHACTR1 expression in macrophages that is similar to that of an inflammatory stimulus.
authors.affiliation: Wellcome Trust Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, United Kingdom.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Reschen
authors.affiliation: Wellcome Trust Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, United Kingdom.
authors.forename: Da
authors.initials: D
authors.lastname: Lin
authors.affiliation: Wellcome Trust Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, United Kingdom.
authors.forename: Anil
authors.initials: A
authors.lastname: Chalisey
authors.affiliation: Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford and Department of Cellular Pathology, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Soilleux
authors.affiliation: Wellcome Trust Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, United Kingdom. Electronic address: chris.ocallaghan@ndm.ox.ac.uk.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: O'Callaghan
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D050197:Atherosclerosis / Q000175:diagnosis / Q000235:genetics*; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000235:genetics*; D003331:Coronary Vessels / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology; D005786:Gene Expression Regulation; D059647:Gene-Environment Interaction; D005838:Genotype; D006801:Humans; D007249:Inflammation; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D020641:Polymorphism, Single Nucleotide; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D055815:Young Adult
chemical_list: D008070:Lipopolysaccharides; D008840:Microfilament Proteins; C570134:PHACTR1 protein, human; D014409:Tumor Necrosis Factor-alpha
keywords: Atherosclerosis; Expression quantitative trait locus (eQTL); Functional genomics; Genetic disease; Genetic polymorphism; Genomics; Low-density lipoprotein (LDL); Myocardial infarction; Oxidized low density lipoprotein (oxLDL); PHACTR1