Using DNA microarray screening (GeneFilter 211, Research Genetics, Huntsville, AL) of mRNA from primary human umbilical vein endothelial cells (HUVEC), we identified 52 genes with significantly altered expression under shear stress [25 dynes͞cm 2 for 6 or 24 h (1 dyne ؍ 10 N), compared with matched stationary controls]; including several genes not heretofore recognized to be shear stress responsive. We examined mRNA expression of nine genes by Northern blot analysis, which confirmed the results obtained on DNA microarrays. Thirty-two genes were up-regulated (by more than 2-fold), the most enhanced being cytochromes P450 1A1 and 1B1, zinc finger protein EZF͞GKLF, glucocorticoid-induced leucine zipper protein, argininosuccinate synthase, and human prostaglandin transporter. Most dramatically decreased (by more than 2-fold) were connective tissue growth factor, endothelin-1, monocyte chemotactic protein-1, and spermidine͞spermine N1-acetyltransferase. The changes observed suggest several potential mechanisms for increased NO production under shear stress in endothelial cells.
During the past 15 years, over 40 genes have been identified as being regulated by shear stress in endothelial cells (1-4). Shear stress responsive genes are involved in cell proliferation, differentiation, maintenance of vascular tone, thrombosis, cellmatrix and cell-cell adhesion, and modulation of the inflammatory͞immune system. The identification of such genes is important not only for developing a fundamental understanding of how endothelial cells work, but also for understanding and treating pathological conditions that are influenced by shear stress, such as thrombosis, restenosis, and atherosclerosis (5, 6).Most of the genes that have been shown to be regulated by shear stress were identified by using traditional techniques such as Northern blot analysis or reverse transcriptase PCR (7-9). The main limitation of these techniques is that only one gene or at best a handful of genes can be studied in one experiment. When multiple genes are studied by using traditional methods, the experiments usually require a reiteration of the detection procedure for each gene. Investigators must therefore be very selective in the genes they choose to study, necessitating a priori information linking the chosen genes to shear stress. Thus, these experiments generally tend to validate or disprove specific hypotheses and do not lead to the discovery of unexpected differentially expressed genes. However, DNA microarray technology allows researchers to study several thousands of genes at one time. In addition to identifying unexpected genes, this technology also has the power to lead to the development of new hypotheses concerning how cells respond to shear stress and identification of coregulated pathways responsive to the mechanical environment of the cell.We used DNA GeneFilter GF211 from Research Genetics (Huntsville, AL; ref. 10), which contains over 4,000 named human genes, to identify genes altered by shear stress in primary human umbilical vein en...
