Laminar shear stress acts as a switch to regulate divergent functions of NF‐κB in endothelial cells

• DOI: 10.1096/fj.06-8059com
• Publication Date: 2007-06-09T04:58:56Z
• Authors: Jason Partridge; Harald Carlsen; Karine Enesa; Hera Chaudhury; Mustafa Zakkar; Le Luong; Anne Kinderlerer; Mike Johns; Rune Blomhoff; Justin C. Mason; Dorian O. Haskard; Paul C. Evans
• Keywords: 0301 basic medicine; 03 medical and health sciences; Base Sequence; Transcription, Genetic; Reverse Transcriptase Polymerase Chain Reaction; NF-kappa B; Humans; Endothelium, Vascular; RNA, Messenger; Stress, Mechanical; Cells, Cultured; DNA Primers

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.