The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor has broad signaling effects in primary effusion lymphoma cells.
Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8 [HHV-8]) is a gamma-2-herpesvirus responsible for Kaposi's sarcoma as well as primary effusion lymphoma (PEL). KSHV is a lymphotropic virus that has pirated many mammalian genes involved in inflammation, cell cycle control, and angiogenesis. Among these is the early lytic viral G protein-coupled receptor (vGPCR), a homologue of the human interleukin-8 (IL-8) receptor. When expressed, vGPCR is constitutively active and can signal via mitogen- and stress-activated kinases. In certain models it activates the transcriptional potential of NF-kappaB and activator protein 1 (AP-1) and induces vascular endothelial growth factor (VEGF) production. Despite its importance to the pathogenesis of all KSHV-mediated disease, little is known about vGPCR activity in hematopoietic cells. To study the signaling potential and downstream effects of vGPCR in such cells, we have developed PEL cell lines that express vGPCR under the control of an inducible promoter. The sequences required for tetracycline-mediated induction were cloned into a plasmid containing adeno-associated virus type 2 elements to enhance integration efficiency. This novel plasmid permitted studies of vGPCR activity in naturally infected KSHV-positive lymphocytes. We show that vGPCR activates ERK-2 and p38 in PEL cells. In addition, it increases the transcription of reporter genes under the control of AP-1, NF-kappaB, CREB, and NFAT, a Ca(2+)-dependent transcription factor important to KSHV lytic gene expression. vGPCR also increases the transcription of KSHV open reading frames 50 and 57, thereby displaying broad potential to affect viral transcription patterns. Finally, vGPCR signaling results in increased PEL cell elaboration of KSHV vIL-6 and VEGF, two growth factors involved in KSHV-mediated disease pathogenesis.
Cannon
Mark
M
Division of International Medicine and Infectious Disease, Department of Medicine, Weill Medical College of Cornell University, New York, New York 10021, USA.
Philpott
Nicola J
NJ
Cesarman
Ethel
E
D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000096:biosynthesis; D004789:Enzyme Activation; D019288:Herpesvirus 8, Human / Q000472:pathogenicity*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008222:Lymphokines / Q000096:biosynthesis; D008228:Lymphoma, Non-Hodgkin / Q000821:virology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D019707:Receptors, Chemokine / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014764:Viral Proteins / Q000502:physiology*
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; C115448:G protein-coupled receptor, Human herpesvirus 8; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D008222:Lymphokines; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D019707:Receptors, Chemokine; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014764:Viral Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases