title: Rap1 GTPase Inhibits Tumor Necrosis Factor-α-Induced Choroidal Endothelial Migration via NADPH Oxidase- and NF-κB-Dependent Activation of Rac1.
abstract: Macrophage-derived tumor necrosis factor (TNF)-α has been found in choroidal neovascularization (CNV) surgically removed from patients with age-related macular degeneration. However, the role of TNF-α in CNV development remains unclear. In a murine laser-induced CNV model, compared with un-lasered controls, TNF-α mRNA was increased in retinal pigment epithelial and choroidal tissue, and TNF-α colocalized with lectin-stained migrating choroidal endothelial cells (CECs). Inhibition of TNF-α with a neutralizing antibody reduced CNV volume and reactive oxygen species (ROS) level around CNV. In CECs, pretreatment with the antioxidant apocynin or knockdown of p22phox, a subunit of NADPH oxidase, inhibited TNF-α-induced ROS generation. Apocynin reduced TNF-α-induced NF-κB and Rac1 activation, and inhibited TNF-α-induced CEC migration. TNF-α-induced Rac1 activation and CEC migration were inhibited by NF-κB inhibitor Bay11-7082. Overexpression of Rap1a prevented TNF-α-induced ROS generation and reduced NF-κB and Rac1 activation. Activation of Rap1 by 8-(4-chlorophenylthio)adenosine-2'-O-Me-cAMP prevented TNF-α-induced CEC migration and reduced laser-induced CNV volume, ROS generation, and activation of NF-κB and Rac1. These findings provide evidence that active Rap1a inhibits TNF-α-induced CEC migration by inhibiting NADPH oxidase-dependent NF-κB and Rac1 activation and suggests that Rap1a de-escalates CNV development by interfering with ROS-dependent signaling in several steps of the pathogenic process.
authors.affiliation: The John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.affiliation: The John A. Moran Eye Center, University of Utah, Salt Lake City, Utah.
authors.forename: Lori
authors.initials: L
authors.lastname: Fotheringham
authors.affiliation: Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Erika S
authors.initials: ES
authors.lastname: Wittchen
authors.affiliation: The John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. Electronic address: me.hartnett@hsc.utah.edu.
authors.forename: M Elizabeth
authors.initials: ME
authors.lastname: Hartnett
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D002829:Choroid / Q000378:metabolism; D020256:Choroidal Neovascularization / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D008810:Mice, Inbred C57BL; D019255:NADPH Oxidases / Q000502:physiology*; D016328:NF-kappa B / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism* / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism* / Q000502:physiology
chemical_list: D016328:NF-kappa B; D009479:Neuropeptides; C484602:Rac1 protein, mouse; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D019255:NADPH Oxidases; D020830:rac1 GTP-Binding Protein