title: Large impact of low concentration oxidized LDL on angiogenic potential of human endothelial cells: a microarray study.
abstract: Oxidized LDL (ox-LDL) is a key factor in atherogenesis. It is taken up by endothelial cells primarily by ox-LDL receptor-1 (LOX-1). To elucidate transcriptional responses, we performed microarray analysis on human coronary artery endothelial cells (HCAECs) exposed to small physiologic concentration of ox-LDL- 5 µg/ml for 2 and 12 hours. At 12 hours, cultures treated with ox-LDL exhibited broad shifts in transcriptional activity involving almost 1500 genes (>1.5 fold difference, p<0.05). Resulting transcriptome was enriched for genes associated with cell adhesion (p<0.002), angiogenesis (p<0.0002) and migration (p<0.006). Quantitative PCR analysis revealed that LOX-1 expression in HCAECs is at least an order of magnitude greater than the expression of other major ox-LDL specific receptors CD36 and MSR1. In keeping with the data on LOX-1 expression, pre-treatment of HCAECs with LOX-1 neutralizing antibody resulted in across-the-board inhibition of cellular response to ox-LDL. Ox-LDL upregulated a number of pro-angiogenic genes including multiple receptors, ligands and transcription factors and altered the expression of a number of genes implicated in both stimulation and inhibition of apoptosis. From a functional standpoint, physiologic concentrations of ox-LDL stimulated tube formation and inhibited susceptibility to apoptosis in HCAECs. In addition, ox-LDL exposure resulted in upregulation of miR-1974, miR-1978 and miR-21 accompanied with significant over-presentation of their target genes in the downregulated portion of ox-LDL transcriptome. Our observations indicate that ox-LDL at physiologic concentrations induces broad transcriptional responses which are mediated by LOX-1, and are, in part, shaped by ox-LDL-dependent miRNAs. We also suggest that angiogenic effects of ox-LDL are partially based on upregulation of several receptors that render cells hypersensitive to angiogenic stimuli.
authors.affiliation: Central Arkansas Healthcare System and the University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA. mkhaidakov@uams.edu
authors.forename: Magomed
authors.initials: M
authors.lastname: Khaidakov
authors.forename: Sona
authors.initials: S
authors.lastname: Mitra
authors.forename: Xianwei
authors.initials: X
authors.lastname: Wang
authors.forename: Zufeng
authors.initials: Z
authors.lastname: Ding
authors.forename: Nalini
authors.initials: N
authors.lastname: Bora
authors.forename: Valery
authors.initials: V
authors.lastname: Lyzogubov
authors.forename: Francesco
authors.initials: F
authors.lastname: Romeo
authors.forename: Steven A
authors.initials: SA
authors.lastname: Schichman
authors.forename: Jawahar L
authors.initials: JL
authors.lastname: Mehta
mesh_terms: D057134:Antibodies, Neutralizing / Q000276:immunology; D017209:Apoptosis; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008077:Lipoproteins, LDL / Q000276:immunology / Q000378:metabolism*; D009389:Neovascularization, Pathologic; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D059467:Transcriptome
chemical_list: D057134:Antibodies, Neutralizing; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein