title: Characterization of the differential response of endothelial cells exposed to normal and elevated laminar shear stress.
abstract: Most acute coronary events occur in the upstream region of stenotic atherosclerotic plaques that experience laminar shear stress (LSS) elevated above normal physiological levels. Many studies have described the atheroprotective effect on endothelial behavior of normal physiological LSS (approximately 15 dynes/cm(2)) compared to static or oscillatory shear stress (OSS), but it is unknown whether the levels of elevated shear stress imposed by a stenotic plaque would preserve, enhance or reverse this effect. Therefore we used transcriptomics and related functional analyses to compare human endothelial cells exposed to laminar shear stress of 15 (LSS15-normal) or 75 dynes/cm(2) (LSS75-elevated). LSS75 upregulated expression of 145 and downregulated expression of 158 genes more than twofold relative to LSS15. Modulation of the metallothioneins (MT1-G, -M, -X) and NADPH oxidase subunits (NOX2, NOX4, NOX5, and p67phox) accompanied suppression of reactive oxygen species production at LSS75. Shear induced changes in dual specificity phosphatases (DUSPs 1, 5, 8, and 16 increasing and DUSPs 6 and 23 decreasing) were observed as well as reduced ERK1/2 but increased p38 MAP kinase phosphorylation. Amongst vasoactive substances, endothelin-1 expression decreased whereas vasoactive intestinal peptide (VIP) and prostacyclin expression increased, despite which intracellular cAMP levels were reduced. Promoter analysis by rVISTA identified a significant over representation of ATF and Nrf2 transcription factor binding sites in genes upregulated by LSS75 compared to LSS15. In summary, LSS75 induced a specific change in behavior, modifying gene expression, reducing ROS levels, altering MAP kinase signaling and reducing cAMP levels, opening multiple avenues for future study.
authors.affiliation: Bristol Heart Institute, University of Bristol (Clinical Sciences South Bristol), Bristol, UK. steve.white@bris.ac.uk
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: White
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hayes
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Lehoux
authors.forename: Jamie Y
authors.initials: JY
authors.lastname: Jeremy
authors.forename: Anton J G
authors.initials: AJ
authors.lastname: Horrevoets
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Newby
mesh_terms: D051696:Activating Transcription Factors / Q000378:metabolism; D001665:Binding Sites; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D015536:Down-Regulation; D054637:Dual-Specificity Phosphatases / Q000096:biosynthesis; D042783:Endothelial Cells / Q000502:physiology*; D019332:Endothelin-1 / Q000096:biosynthesis; D011464:Epoprostenol / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D008668:Metallothionein / Q000096:biosynthesis; D019255:NADPH Oxidases / Q000096:biosynthesis; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D033081:Shear Strength; D013314:Stress, Mechanical; D015854:Up-Regulation; D014660:Vasoactive Intestinal Peptide / Q000096:biosynthesis
chemical_list: D051696:Activating Transcription Factors; D019332:Endothelin-1; D051267:NF-E2-Related Factor 2; D017382:Reactive Oxygen Species; D014660:Vasoactive Intestinal Peptide; D008668:Metallothionein; D011464:Epoprostenol; D000242:Cyclic AMP; D019255:NADPH Oxidases; D048049:Extracellular Signal-Regulated MAP Kinases; D054637:Dual-Specificity Phosphatases