title: Inhibition of endocytosis exacerbates TNF-α-induced endothelial dysfunction via enhanced JNK and p38 activation.
abstract: Tumor necrosis factor-α (TNF-α) is a pro-inflammatory cytokine that causes endothelial dysfunction. Endocytosis of TNF-α receptors (TNFR) precedes endosomal reactive oxygen species (ROS) production, which is required for NF-κB activation in vascular smooth muscle cells. It is unknown how endocytosis of TNFRs impacts signaling in endothelial cells. We hypothesized that TNF-α-induced endothelial dysfunction is induced by both endosomal and cell surface events, including NF-κB and mitogen-activated protein kinases (MAPKs) activation, and endocytosis of the TNFR modifies signaling. Mesenteric artery segments from C57BL/6 mice were treated with TNF-α (10 ng/ml) for 22 h in tissue culture, with or without signaling inhibitors (dynasore for endocytosis, SP600125 for JNK, SB203580 for p38, U0126 for ERK), and vascular function was assessed. Endothelium-dependent relaxation to acetylcholine (ACh) was impaired by TNF-α, and dynasore exacerbated this, whereas JNK or p38 inhibition prevented these effects. In cultured endothelial cells from murine mesenteric arteries, dynasore potentiated JNK and p38 but not ERK phosphorylation and promoted cell death. NF-κB activation by TNF-α was decreased by dynasore. JNK inhibition dramatically increased both the magnitude and duration of TNF-α-induced NF-κB activation and potentiated intercellular adhesion molecule-1 (ICAM-1) activation. Dynasore still inhibited NF-κB activation in the presence of SP600125. Thus TNF-α-induced endothelial dysfunction is both JNK and p38 dependent. Endocytosis modulates the balance of NF-κB and MAPK signaling, and inhibition of NF-κB activation by JNK limits this pro-proliferative signal, which may contribute to endothelial cell death in response to TNF-α.
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Hyehun
authors.initials: H
authors.lastname: Choi
authors.forename: Hong N
authors.initials: HN
authors.lastname: Nguyen
authors.forename: Fred S
authors.initials: FS
authors.lastname: Lamb
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D006835:Hydrazones / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D008297:Male; D008638:Mesenteric Arteries; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: JNK; NF-κB; endocytosis; endothelial dysfunction; p38 kinase; tumor necrosis factor-α