title: Inhibition of Kaposi's sarcoma-associated herpesvirus lytic replication by HIV-1 Nef and cellular microRNA hsa-miR-1258.
abstract: Kaposi's sarcoma-associated herpesvirus (KSHV) is causally linked to several AIDS-related malignancies, including Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease. The interaction of human immunodeficiency virus type 1 (HIV-1) and KSHV has a central role in promoting the aggressive manifestations of AIDS-KS. We have previously shown that negative factor (Nef), a secreted HIV-1 protein, synergizes with KSHV viral interleukin-6 (vIL-6) to promote angiogenesis and tumorigenesis by activating the AKT pathway (X. Zhu, et al., Oncogene, 22 April 2013, http://dx.doi.org/10.1038/onc.2013.136). Here, we further demonstrated the role of soluble and ectopic Nef in the regulation of KSHV latency. We found that both soluble Nef protein and ectopic expression of Nef by transfection suppressed the expression of KSHV viral lytic mRNA transcripts and proteins and the production of infectious viral particles. MicroRNA (miRNA) microarray analysis identified a number of Nef-regulated miRNAs. Bioinformatics and luciferase reporter analyses showed that one of the Nef-upregulated miRNAs, cellular miRNA 1258 (hsa-miR-1258), directly targeted a seed sequence in the 3' untranslated region (UTR) of the mRNA encoding the major lytic switch protein (RTA), which controls KSHV reactivation from latency. Ectopic expression of hsa-miR-1258 impaired RTA synthesis and enhanced Nef-mediated inhibition of KSHV replication, whereas repression of hsa-miR-1258 has the opposite effect. Mutation of the seed sequence in the RTA 3'UTR abolished downregulation of RTA by hsa-miR-1258. Collectively, these novel findings demonstrate that, by regulating cellular miRNA, Nef may inhibit KSHV replication to promote viral latency and contribute to the pathogenesis of AIDS-related malignancies.
  
  
  OBJECTIVE
  This study found that Nef, a secreted HIV-1 protein, suppressed KSHV lytic replication to promote KSHV latency. Mechanistic studies indicated that a Nef-upregulated cellular miRNA, hsa-miR-1258, inhibits KSHV replication by directly targeting a seed sequence in the KSHV RTA 3'UTR. These results illustrate that, in addition to viral miRNAs, cellular miRNAs also play an important role in regulating the life cycle of KSHV. Overall, this is the first study to report the involvement of Nef in KSHV latency, implying its likely important role in the pathogenesis of AIDS-related malignancies.
authors.affiliation: State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, People's Republic of China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Yan
authors.forename: Xinting
authors.initials: X
authors.lastname: Ma
authors.forename: Chenyou
authors.initials: C
authors.lastname: Shen
authors.forename: Xu
authors.initials: X
authors.lastname: Cao
authors.forename: Ninghan
authors.initials: N
authors.lastname: Feng
authors.forename: Di
authors.initials: D
authors.lastname: Qin
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Zhu
authors.forename: Shou-Jiang
authors.initials: SJ
authors.lastname: Gao
authors.forename: Chun
authors.initials: C
authors.lastname: Lu
mesh_terms: D020869:Gene Expression Profiling; D015497:HIV-1 / Q000502:physiology*; D019288:Herpesvirus 8, Human / Q000502:physiology*; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D046228:Microarray Analysis; D014762:Viral Interference; D017735:Virus Latency; D014779:Virus Replication; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
chemical_list: C576996:MIRN1258 microRNA, human; D035683:MicroRNAs; D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1