Gene profile for differentiation of vascular adventitial myofibroblasts

Our previous study demonstrated that TGF-beta1 could induce the differentiation of vascular adventitial fibroblasts (AFs) to myofibroblasts (MFs). The aim of this study was to identify the genes which might be responsible for the cell phenotypic change using genechips. Cultured rat AFs were treated with TGF-beta1 (10 ng/ml) for 0 min, 5 min, 15 min, 2 h, 12 h and 24 h, respectively. Then the cells were gathered to prepare total RNA. We examined TGF-beta1-induced gene expression profiling using Affymetrix oligonucleotide microarrays and analyzed data by GCOS1.2 software. Moreover, expressional similarity was measured by hierarchical clustering. Some of genechip results were confirmed by real-time quantitative RT-PCR. Microarray analysis identified 2121 genes with a 2-fold change or above after TGF-beta1 stimulation. 1318 genes showed a greater than 2-fold increase and 761 genes were reduced 2 folds or more at mRNA levels, whereas a small portion of the total regulated genes (42 genes) displayed dynamically up- and down-regulated pattern. Genes were further segregated for early (peak at 5 min, 15 min and/or 2 h), late (peak at 12 h and/or 24 h), and sustained (2-fold change or above at five time points) temporal response groups according to the time of their peak expression level. Among 1318 up-regulated genes, 333 genes (25.3%) responded rapidly to TGF-beta1 and 159 genes (12.1%) responded in a sustained manner. Most genes (826, 62.6%) were regulated at 12 h or later. For the 761 down-regulated genes, numbers of early and late responsive genes were 335 (44%) and 267 (36.1%), respectively. There were also 159 genes, 19.9% of total down-regulated genes, decreased at five time points treated by TGF-beta1. The results suggested that the gene expressions of secreted phosphoprotein 1 (APP1) and Rho-associated coiled-coil forming kinase 2 (ROCK2) had the same trends as alpha-smooth muscle-actin, a marker of MF differentiation. In addition, the gene expression of potassium voltage-gated channel, Shal-related family and member 2 (KCND2) was up-regulated. Furthermore, it was found that endothelin 1 (EDN1), some complement components, NADPH oxidase 4 (NOX4) and NAD(P)H dehydrogenase, quinone 1 (NQO1) might be involved in MF differentiation. Using microarrary technique, we confirmed some genes that have been identified by other techniques were implicated in MF differentiation and observed new genes involved in this process. Our results suggest that gene expression profiling study is helpful in identifying genes and pathways potentially involved in cell differentiation.