title: Regulation of NF-kappaB inhibitor IkappaBalpha and viral replication by a KSHV microRNA.
abstract: Kaposi's sarcoma-associated herpesvirus (KSHV) is causally linked to several acquired immune deficiency syndrome-related malignancies, including Kaposi's sarcoma, primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease. Control of viral lytic replication is essential for KSHV latency, evasion of the host immune system and induction of tumours. Here, we show that deletion of a 14 microRNA (miRNA) cluster from the KSHV genome significantly enhances viral lytic replication as a result of reduced NF-kappaB activity. The miRNA cluster regulates the NF-kappaB pathway by reducing expression of IkappaBalpha protein, an inhibitor of NF-kappaB complexes. Computational and miRNA seed mutagenesis analyses were used to identify KSHV miR-K1, which directly regulates the IkappaBalpha protein level by targeting the 3'UTR of its transcript. Expression of miR-K1 is sufficient to rescue NF-kappaB activity and inhibit viral lytic replication, whereas inhibition of miR-K1 in KSHV-infected PEL cells has the opposite effect. Thus, KSHV encodes an miRNA to control viral replication by activating the NF-kappaB pathway. These results demonstrate an important role for KSHV miRNAs in regulating viral latency and lytic replication by manipulating the host survival pathway.
authors.affiliation: Tumor Virology Program, Greehey Children's Cancer Research Institute, and Cancer Therapy and Research Center, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
authors.forename: Xiufen
authors.initials: X
authors.lastname: Lei
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Bai
authors.forename: Fengchun
authors.initials: F
authors.lastname: Ye
authors.forename: Jianping
authors.initials: J
authors.lastname: Xie
authors.forename: Chan-Gil
authors.initials: CG
authors.lastname: Kim
authors.forename: Yufei
authors.initials: Y
authors.lastname: Huang
authors.forename: Shou-Jiang
authors.initials: SJ
authors.lastname: Gao
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D005455:Fluorescent Antibody Technique; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014779:Virus Replication / Q000235:genetics / Q000502:physiology*
chemical_list: D020672:I-kappa B Proteins; D035683:MicroRNAs; C000606204:NFKBIA protein, human; D000072000:NF-KappaB Inhibitor alpha