title: Laminar shear stress acts as a switch to regulate divergent functions of NF-kappaB in endothelial cells.
abstract: Regions of the arterial tree exposed to laminar flow, which exerts high shear stress, are protected from inflammation, endothelial cell (EC) death and atherosclerosis. TNFalpha activates NF-kappaB transcription factors, which potentially exert dual functions by inducing both proinflammatory and cytoprotective transcripts. We assessed whether laminar shear stress protects EC by modulating NF-kappaB function. Human umbilical vein EC (HUVEC) were cultured under shear stress (12 dynes/cm2 for 16 h) using a parallel-plate flow chamber or were maintained in static conditions. Comparative real-time PCR revealed that preshearing significantly alters transcriptional responses to TNFalpha by enhancing the expression of cytoprotective molecules (Bcl-2, MnSOD, GADD45beta, A1) and suppressing proinflammatory transcripts (E-selectin, VCAM-1, IL-8). We demonstrated using assays of nuclear localization, NF-kappaB subunit phosphorylation, DNA-binding, and transcriptional activity that NF-kappaB is activated by TNFalpha in presheared HUVEC. Furthermore, a specific inhibitor revealed that NF-kappaB is essential for the induction of cytoprotective transcripts in presheared EC. Finally, we observed that NF-kappaB can be activated in vascular endothelium exposed to laminar shear stress in NF-kappaB-luciferase reporter mice, thus validating our cell culture experiments. We conclude that shear stress primes EC for enhanced NF-kappaB-dependent cytoprotective responsiveness while attenuating proinflammatory activation. Thus modulation of NF-kappaB function may underlie the atheroprotective effects of laminar shear stress.
authors.affiliation: BHF Cardiovascular Medicine, National Heart and Lung Institute, Imperial College London, Hammersmith Campus, Du Cane Rd., London W12 ONN, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Partridge
authors.forename: Harald
authors.initials: H
authors.lastname: Carlsen
authors.forename: Karine
authors.initials: K
authors.lastname: Enesa
authors.forename: Hera
authors.initials: H
authors.lastname: Chaudhury
authors.forename: Mustafa
authors.initials: M
authors.lastname: Zakkar
authors.forename: Le
authors.initials: L
authors.lastname: Luong
authors.forename: Anne
authors.initials: A
authors.lastname: Kinderlerer
authors.forename: Mike
authors.initials: M
authors.lastname: Johns
authors.forename: Rune
authors.initials: R
authors.lastname: Blomhoff
authors.forename: Justin C
authors.initials: JC
authors.lastname: Mason
authors.forename: Dorian O
authors.initials: DO
authors.lastname: Haskard
authors.forename: Paul C
authors.initials: PC
authors.lastname: Evans
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers; D016328:NF-kappa B; D012333:RNA, Messenger