title: A potential alpha-helix motif in the amino terminus of LANA encoded by Kaposi's sarcoma-associated herpesvirus is critical for nuclear accumulation of HIF-1alpha in normoxia.
abstract: Hypoxia-inducible factor 1 (HIF-1) is a ubiquitously expressed transcriptional regulator involved in induction of numerous genes associated with angiogenesis and tumor growth. Kaposi's sarcoma, associated with increased angiogenesis, is a highly vascularized, endothelial cell-derived tumor. Previously, we have shown that the latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) targets the HIF-1alpha suppressors von Hippel-Lindau protein and p53 for degradation via its suppressor of cytokine signaling-box motif, which recruits the EC5S ubiquitin complex. Here we further show that HIF-1alpha was aberrantly accumulated in KSHV latently infected primary effusion lymphoma (PEL) cells, as well as HEK293 cells infected with KSHV, and also show that a potential alpha-helical amino-terminal domain of LANA was important for HIF-1alpha nuclear accumulation in normoxic conditions. Moreover, we have now determined that this association was dependent on the residues 46 to 89 of LANA and the oxygen-dependent degradation domain of HIF-1alpha. Introduction of specific small interfering RNA against LANA into PEL cells also resulted in a diminished nuclear accumulation of HIF-1alpha. Therefore, these data show that LANA can function not only as an inhibitor of HIF-1alpha suppressor proteins but can also induce nuclear accumulation of HIF-1alpha during KSHV latent infection.
authors.affiliation: Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, University of Pennsylvania Medical School, Philadelphia, PA 19104, USA.
authors.forename: Qiliang
authors.initials: Q
authors.lastname: Cai
authors.forename: Masanao
authors.initials: M
authors.lastname: Murakami
authors.forename: Huaxin
authors.initials: H
authors.lastname: Si
authors.forename: Erle S
authors.initials: ES
authors.lastname: Robertson
mesh_terms: D020816:Amino Acid Motifs; D000956:Antigens, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012514:Sarcoma, Kaposi / Q000378:metabolism* / Q000821:virology*
chemical_list: D000956:Antigens, Viral; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; C109540:latency-associated nuclear antigen