Differential activation of murine herpesvirus 68- and Kaposi's sarcoma-associated herpesvirus-encoded ORF74 G protein-coupled receptors by human and murine chemokines.
Infection of mice with murine gammaherpesvirus 68 (MHV-68) is a well-characterized small animal model for the study of gammaherpesvirus infection. MHV-68 belongs to the same herpesvirus family as herpesvirus saimiri (HVS) of New World squirrel monkeys and human herpesvirus 8 (HHV-8) (also referred to as Kaposi's sarcoma-associated herpesvirus [KSHV]). The open reading frame ORF74 of HVS, KSHV, and MHV-68 encodes a protein with homology to G protein-coupled receptors and chemokine receptors in particular. ORF74 of KSHV (human ORF74 [hORF74]) is highly constitutively active and has been implicated in the pathogenesis of Kaposi's sarcoma. MHV-68-encoded ORF74 (mORF74) is oncogenic and has been implicated in viral replication and reactivation from latency. Here, we show that mORF74 is a functional chemokine receptor. Chemokines with an N-terminal glutamic acid-leucine-arginine (ELR) motif (e.g., KC and macrophage inflammatory protein 2) act as agonists on mORF74, activating phospholipase C, NF-kappaB, p44/p42 mitogen-activated protein kinase, and Akt signaling pathways and inhibiting formation of cyclic AMP. Using (125)I-labeled CXCL1/growth-related oncogene alpha as a tracer, we show that murine CXCL10/gamma interferon-inducible protein 10 binds mORF74, and functional assays show that it behaves as an antagonist for this virally encoded G protein-coupled receptor. Profound differences in the upstream activation of signal transduction pathways between mORF74 and hORF74 were found. Moreover, in contrast to hORF74, no constitutive activity of mORF74 could be detected.
Verzijl
Dennis
D
Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands.
Fitzsimons
Carlos P
CP
Van Dijk
Marie
M
Stewart
James P
JP
Timmerman
Henk
H
Smit
Martine J
MJ
Leurs
Rob
R
D000818:Animals; D019556:COS Cells; D054357:Chemokine CXCL10; D018925:Chemokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D019743:Chemokines, CXC / Q000378:metabolism; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000378:metabolism; D019288:Herpesvirus 8, Human / Q000378:metabolism*; D006801:Humans; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D019707:Receptors, Chemokine / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018144:Rhadinovirus / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D010738:Type C Phospholipases / Q000378:metabolism; D014764:Viral Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism*
D054357:Chemokine CXCL10; D018925:Chemokines; D019743:Chemokines, CXC; D016328:NF-kappa B; C105181:ORF74 protein, Human herpesvirus 8; D019707:Receptors, Chemokine; D043562:Receptors, G-Protein-Coupled; D014764:Viral Proteins; D000242:Cyclic AMP; D010738:Type C Phospholipases