Prolonged fluid shear stress induces a distinct set of endothelial cell genes, most specifically lung Krüppel-like factor (KLF2).
The endothelium expresses a large repertoire of genes under apparent transcriptional control of biomechanical forces, many of which are neither cell-type nor flow specific. We set out to identify genes that are uniquely flow responsive in human vascular endothelial cells. Transcriptional profiling using commercial DNA microarrays identified 12 of 18 000 genes that were modulated at least 5-fold after 24 hours of steady laminar flow (25 dyne/cm(2)). After a 7-day exposure to unidirectional pulsatile flow (19 +/- 12 dyne/cm(2)), only 3 of 12 remained elevated at least 5-fold. A custom microarray of ~300 vascular cell-related gene fragments was constructed, and expression analysis revealed that many flow-induced genes are also induced by at least one of the following agents: tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), transforming growth factor-beta, vascular endothelial growth factor, or thrombin, indicating a more general role in adaptive or stress responses. Most flow-induced genes were also induced by TNF-alpha but not IL-1beta, suggesting the involvement of reactive oxygen species. A limited panel of genes that are unique for flow-exposed cultures was identified, including lung Krüppel-like factor (LKLF/KLF2) and cytochrome P450 1B1 (CYP1B1). In marked contrast, both these genes were substantially repressed by TNF-alpha. LKLF but not CYP1B1 mRNA was detected exclusively in the vascular endothelium of healthy human aorta by in situ hybridization and appeared to be flow regulated. To date LKLF is the first endothelial transcription factor that is uniquely induced by flow and might therefore be at the molecular basis of the physiological healthy, flow-exposed state of the endothelial cell.
Dekker
Rob J
RJ
Department of Biochemistry, Academic Medical Center, University of Amsterdam, The Netherlands.
van Soest
Simone
S
Fontijn
Ruud D
RD
Salamanca
Sonia
S
de Groot
Philip G
PG
VanBavel
Ed
E
Pannekoek
Hans
H
Horrevoets
Anton J G
AJ
D001161:Arteriosclerosis / Q000235:genetics / Q000378:metabolism; D001189:Aryl Hydrocarbon Hydroxylases; D002460:Cell Line; D002648:Child; D062507:Claudin-5; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics; D004730:Endothelium, Vascular / Q000473:pathology / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013314:Stress, Mechanical; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics*; D016335:Zinc Fingers
C107466:CLDN5 protein, human; D062507:Claudin-5; C096161:KLF2 protein, human; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D015534:Trans-Activators; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1