Lymphotoxin-alpha 1 beta 2 and LIGHT induce classical and noncanonical NF-kappa B-dependent proinflammatory gene expression in vascular endothelial cells.
Activation of the classical and noncanonical NF-kappaB pathways by ligation of the lymphotoxin (LT)-beta receptor (LTbetaR) plays a crucial role in lymphoid organogenesis and in the generation of ectopic lymphoid tissue at sites of chronic inflammation. Within these microenvironments, LTbetaR signaling regulates the phenotype of the specialized high endothelial cells. However, the direct effects of LTbetaR ligation on endothelial cells remain unclear. We therefore questioned whether LTbetaR ligation could directly activate endothelial cells and regulate classical and noncanonical NF-kappaB-dependent gene expression. We demonstrate that the LTbetaR ligands LIGHT and LTalpha1beta2 activate both NF-kappaB pathways in HUVECs and human dermal microvascular endothelial cells (HDMEC). Classical pathway activation was less robust than TNF-induced signaling; however, only LIGHT and LTalpha1beta2 and not TNF activated the noncanonical pathway. LIGHT and LTalpha1beta2 induced the expression of classical NF-kappaB-dependent genes in HUVEC, including those encoding the adhesion molecules E-selectin, ICAM-1, and VCAM-1. Consistent with this stimulation, LTbetaR ligation up-regulated T cell adhesion to HUVEC. Furthermore, the homeostatic chemokine CXCL12 was up-regulated by LIGHT and LTalpha1beta2 but not TNF in both HUVEC and HDMEC. Using HUVEC retrovirally transduced with dominant negative IkappaB kinase alpha, we demonstrate that CXCL12 expression is regulated by the noncanonical pathway in endothelial cells. Our findings therefore demonstrate that LTbetaR ligation regulates gene expression in endothelial cells via both NF-kappaB pathways and we identify CXCL12 as a bona fide noncanonical NF-kappaB-regulated gene in these cells.
Madge
Lisa A
LA
Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, University of Pennsylvania School of Veterinary Medicine, and The Joseph Stokes Jr. Research Institute, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Kluger
Martin S
MS
Orange
Jordan S
JS
May
Michael J
MJ
D002448:Cell Adhesion / Q000235:genetics / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D004730:Endothelium, Vascular / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology*; D008024:Ligands; D053361:Lymphotoxin alpha1, beta2 Heterotrimer / Q000378:metabolism / Q000502:physiology*; D053259:Lymphotoxin beta Receptor / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D008233:Lymphotoxin-alpha / Q000378:metabolism / Q000502:physiology; D053308:Lymphotoxin-beta / Q000378:metabolism / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D012867:Skin / Q000098:blood supply / Q000166:cytology / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14 / Q000378:metabolism / Q000502:physiology*; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
D015815:Cell Adhesion Molecules; D018836:Inflammation Mediators; C505886:LTB protein, human; D008024:Ligands; D053361:Lymphotoxin alpha1, beta2 Heterotrimer; D053259:Lymphotoxin beta Receptor; D008233:Lymphotoxin-alpha; D053308:Lymphotoxin-beta; D016328:NF-kappa B; C505914:TNFSF14 protein, human; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14