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The effects of 3OC12-HSL on global gene expression in primary human aortic endothelial cells (HAEC).

ABSTRACT: Analysis of the effect of a bacterial quorum sensing molecule on in-vitro culture of human endothelial cells at gene expression levels. Objective: Chronic infection has long been postulated as a stimulus for atherogenesis. Pseudomonas aeruginosa infection has been associated with increased atherosclerosis in rats, and the bacteria produce a quorum sensing molecule 3-oxo-dodecynoyl-homoserine lactone (3OC12-HSL) that is critical for colonization and virulence. Paraoxonase 2 (PON2) hydrolyzes 3OC12-HSL and also protects against the effects of oxidized phospholipids thought to contribute to atherosclerosis. We now report the response of human aortic endothelial cells (HAEC) to 3OC12-HSL and oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (Ox-PAPC) in relation to PON2 expression. Methods and Results: Using expression profiling and network modeling, we identified the unfolded protein response (UPR), cell cycle genes, and the MAPK signaling pathway to be heavily involved in the HAEC response to 3OC12-HSL. The network also showed striking similarities to a network created based on HAEC response to Ox-PAPC, a major component of minimally-modified LDL. HAEC in which PON2 was silenced by siRNA showed increased pro-inflammatory and UPR responses when treated with 3OC12-HSL or Ox-PAPC. Conclusion: 3OC12-HSL and Ox-PAPC influence similar inflammatory pathways. Quorum sensing molecules such as 3OC12-HSL contribute to the pro-atherogenic effects of chronic infection and the anti-atherogenic effects of PON2 include destruction of quorum sensing molecules.

ORGANISM(S): Homo sapiens

PROVIDER: GSE26295 | GEO | 2010/12/30

SECONDARY ACCESSION(S): PRJNA135057

REPOSITORIES: GEO

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Project description:Oxidized phospholipids are thought to promote atherogenesis by stimulating endothelial cells (ECs) to produce inflammatory cytokines, such as IL-8. In studies with mouse models, we previously demonstrated that genetic variation in inflammatory responses of endothelial cells to oxidized lipids contributes importantly to atherosclerosis susceptibility. We now show that similar variations occur in cultured aortic ECs derived from multiple heart transplant donors. These variations were stably maintained between passages and, thus, reflect either genetic or epigenetic regulatory differences. Expression array analysis of aortic EC cultures derived from 12 individuals revealed that >1,000 genes were regulated by oxidized phospholipids. We have used the observed variations in the sampled population to construct a gene coexpression network comprised of 15 modules of highly connected genes. We show that several identified modules are significantly enriched in genes for known pathways and confirm a module enriched for unfolded protein response (UPR) genes using siRNA and the UPR inducer tunicamycin. On the basis of the constructed network, we predicted that a gene of unknown function (MGC4504) present in the UPR module is a target for UPR transcriptional activator ATF4. Our data also indicate that IL-8 is present in the UPR module and is regulated, in part, by the UPR. We validate these by using siRNA. In conclusion, we show that interindividual variability can be used to group genes into pathways and predict gene-gene regulatory relationships, thus identifying targets potentially involved in susceptibility to common diseases such as atherosclerosis. Twelve individual HAEC lines were treated in duplicate (in 35-mm dishes) for 4 h in media containing PAPC (40 μg/ml) or oxidized PAPC (OxPAPC) at 20 ug/ml or 40 μg/ml. Cytoplasmic RNA was isolated by using an RNAeasy kit (Qiagen) and analyzed on an Agilent 2100 Bioanalyzer (Agilent, Palo Alto, CA) to assess RNA integrity. Double-stranded cDNAs were synthesized from total RNA by using the cDNA Synthesis System (Invitrogen, Carlsbad, CA). Biotin-labeled cRNA was generated and used to probe Affymetrix (Santa Clara, CA) Human Genome U133 Plus 2.0 arrays according to the manufacturer’s recommendations (Affymetrix). The Microarray Suite 5.0 software (Affymetrix) was used to analyze image data and make the absolute call for each measurement. The array data were normalized with the median invariant method (31).

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The effects of 3OC12-HSL on global gene expression in primary human aortic endothelial cells (HAEC).

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