Early transcriptomic response to ldl and oxldl in human vascular smooth muscle cells

Abstract

Backgroun Although nowadays it is well known that the human transcriptome can importantly var according to external or environmental condition, the reflection of this concept when studyin oxidative stress and its direct relationship with gene expression profiling during the proces of atherogenesis has not been thoroughly achieved Objectiv The ability to analyze genome-wide gene expression through transcriptomics ha shown that the genome responds dynamically to diverse stimuli. Here, we describe th transcriptome of human vascular smooth muscle cells (hVSMC) stimulated by nativ and oxidized low-density lipoprotein (nLDL and oxLDL respectively), with the aim o assessing the early molecular changes that induce a response in this cell type resulting in transcriptomic transformation. This expression has been demonstrated in atheroscleroti plaques in vivo and in vitro, particularly in the light of the oxidative modification hypothesi of atherosclerosis Approach and Result Total RNA was isolated with TRIzol reagent (Life Technologies) and quality estimate using an Agilent 2100 bioanalyzer. The transcriptome of hVSMC under different experimenta conditions (1,5 and 24 hours for nLDL and oxLDL) was obtained using the Gene Chip Human Gene 1.0 ST (Affymetrix) designed to measure gene expression of 28,86 well-Annotated genes. A fixed fold-change cut-off corresponding to ± 2 was used to identif genes exhibiting the most significant variation and statistical significance (P< 0.05), and genes validated by qPCR using Taqman probes Conclusion 10 molecular processes were significantly affected in hVSMC: Apoptosis and cell cycle extracellular matrix remodeling, DNA repair, cholesterol efflux, cGMP biosynthesis, endocyti mechanisms, calcium homeostasis, redox balance, membrane trafficking and finally the immune response to inflammation. The evidence we present supporting the hypothesi for the involvement of oxidative modification of several processes and metabolic pathway in atherosclerosis is strengthen by the fact that gene expression patterns obtained whe hVSMC are incubated for a long period of time in the presence of nLDL, correspond ver much the same as when cells are incubated for a short period of time in the presence o chemically modified oxLDL. Our results indicate that under physiological conditions an directly related to specific environmental conditions, LDL particles most probably suffe chemical modifications that initially serve as an alert signal to overcome a harmful stimulu that with time might get transformed to a pathological pattern and therefore consolidate pathological condition.