title: Kaposi's sarcoma-associated herpesvirus K3 and K5 proteins block distinct steps in transendothelial migration of effector memory CD4+ T cells by targeting different endothelial proteins.
abstract: ORFK3 (K3) and ORFK5 (K5) are Kaposi's sarcoma-associated herpesvirus-encoded E3 ubiquitin ligases that differentially reduce surface expression of various proteins in infected cells. In this study, we describe their effects on human dermal microvascular endothelial cells (ECs), a natural target of Kaposi's sarcoma-associated herpesvirus infection. TNF-treated human dermal microvascular ECs transduced to express K5 show reduced capacity to capture effector memory (EM) CD4+ T cells under conditions of venular shear stress. K5 but not K3 transduction significantly reduces ICAM-1 expression and the inhibition of T cell capture was phenocopied by small interfering RNA knockdown of ICAM-1 and by anti-ICAM-1 Ab blocking. Cotransduction with an ICAM-1 truncated construct not subject to K5 ubiquitylation restored EM CD4+ T cell capture. K3 transductants effectively capture EM CD4+ T cells, but fail to support their transendothelial migration (TEM) in response to TCR engagement by superantigen presented by the ECs, leaving intact chemokine-dependent TEM. K3 but not K5 transduction significantly reduces PECAM-1 expression, and the effect on TCR-induced TEM is phenocopied by small interfering RNA knockdown of PECAM-1 and by anti-PECAM-1 Ab blocking. TCR-dependent TEM was restored in K3 transductants cotransduced to express a mutant of PECAM-1 not subject to K3-induced ubiquitylation. EM CD4+ T cells lack any known PECAM-1 counter receptor, but heterophilic engagement of PECAM-1 can involve glycosaminoglycans. In addition, TCR-induced TEM, but not chemokine-induced TEM, appears to involve a heparan- or chondroitin-like molecule on T cells. These results both identify specific roles of K5 and K3 in immune evasion and further differentiate the processes of inflammatory chemokine- versus TCR-dependent recruitment of human EM CD4+ T cells.
authors.affiliation: Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Manes
authors.forename: Simon
authors.initials: S
authors.lastname: Hoer
authors.forename: William A
authors.initials: WA
authors.lastname: Muller
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Lehner
authors.forename: Jordan S
authors.initials: JS
authors.lastname: Pober
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002464:Cell Migration Inhibition / Q000276:immunology*; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D015536:Down-Regulation / Q000276:immunology; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000502:physiology*; D007156:Immunologic Memory; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000037:antagonists & inhibitors / Q000502:physiology*; D025801:Ubiquitin / Q000502:physiology; D014764:Viral Proteins / Q000502:physiology*
chemical_list: C090509:Icam1 protein, mouse; D017874:Immediate-Early Proteins; C456022:K3 protein, Kaposi's sarcoma-associated herpesvirus; C405867:K5 protein, Human herpesvirus 8; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011948:Receptors, Antigen, T-Cell; D025801:Ubiquitin; D014764:Viral Proteins; D018799:Intercellular Adhesion Molecule-1