title: Genipin Enhances Kaposi's Sarcoma-Associated Herpesvirus Genome Maintenance.
abstract: Kaposi's sarcoma-associated herpesvirus (KSHV) is a Gammaherpesvirus that causes acute infection and establishes life-long latency. KSHV causes several human cancers, including Kaposi's sarcoma, an acquired immune deficiency syndrome (AIDS)-related form of non-Hodgkin lymphoma. Genipin, an aglycone derived from geniposide found in Gardenia jasminoides, is known to be an excellent natural cross-linker, strong apoptosis inducer, and antiviral agent. Although evidence suggests antiviral activity of genipin in several in vitro viral infection systems, no inhibitory effect of genipin on KSHV infection has been reported. Thus, our aim was to determine, using the iSLK-BAC16 KSHV infection system, whether genipin has inhibitory effects on KSHV infection. For this purpose, we evaluated biological effects of genipin on KSHV infection and finally determined the underlying mechanisms responsible for the bioactive effects of genipin. A cytotoxicity assay revealed that genipin caused 50% cytotoxicity at 49.5 μM in iSLK-puro (KSHV-negative) cells and at 72.5 μM in iSLK-BAC16 (KSHV-positive) cells. Caspase 3/7 activities were slightly suppressed by genipin treatment in iSLK-BAC16 cells while significantly induced in iSLK-puro cells. Production of the KSHV latency-associated nuclear antigen (LANA), but not that of the R-transactivator (RTA) protein, was significantly induced by genipin treatment at lower concentration. Consistent with the LANA upregulation, KSHV LANA transcripts, but not RTA transcripts, were expressed at a higher level. Furthermore, KSHV intracellular copy numbers were slightly increased at lower concentration of genipin, while KSHV extracellular copy numbers were significantly increased at higher concentration of genipin. Interestingly, genipin treatment at a lower concentration did induce the expression of DNA (cytosine-5)-methyltransferase 1 (DNMT1); however, a co-immunoprecipitation assay showed that the DNMT1 and LANA induced by genipin did not co-precipitate from iSLK-BAC16 cells. Moreover, a chromatin immunoprecipitation assay demonstrated that genipin treatment enhanced the binding of CCCTC-binding factor (CTCF) to the CTCF-binding site in the KSHV latency control region but suppressed the binding of structural maintenance of chromosomes protein 3 (SMC3) to this site. Genipin treatment also led to the recruitment of additional RNA polymerase to the majority of binding sites of some interesting proteins in the KSHV latency control region, which might be related to the extension of S phase in iSLK-BAC16 cells by genipin treatment. Finally, genipin treatment at lower concentration could promote the KSHV latent replication. In contrast, the treatment at higher concentration could induce the KSHV lytic replication. In conclusion, genipin was shown to be an interesting reagent, which we used to manipulate KSHV life cycle in KSHV latently infected cells.
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Miyeon
authors.initials: M
authors.lastname: Cho
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Seok Won
authors.initials: SW
authors.lastname: Jung
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Soomin
authors.initials: S
authors.lastname: Lee
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Kuwon
authors.initials: K
authors.lastname: Son
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Gyu Hwan
authors.initials: GH
authors.lastname: Park
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Jong-Wha
authors.initials: JW
authors.lastname: Jung
authors.affiliation: Department of Medicinal Crop Research, National Institute of Horticultural and Herbal Science, Rural Development Administration, Eumseong, Republic of Korea.
authors.forename: Yu Su
authors.initials: YS
authors.lastname: Shin
authors.affiliation: Department of Life Science, Dongguk University, Goyang, Republic of Korea.
authors.forename: Taegun
authors.initials: T
authors.lastname: Seo
authors.affiliation: College of Pharmacy and Innovative Drug Center, Duksung Women's University, Seoul, Republic of Korea.
authors.lastname: Hyosun Cho
authors.affiliation: College of Pharmacy and Cancer Research Institute and Institute of Microorganism, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Hyojeung
authors.initials: H
authors.lastname: Kang
mesh_terms: D000956:Antigens, Viral / Q000378:metabolism; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D000076246:CCCTC-Binding Factor; D020169:Caspases / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D032062:Gardenia / Q000737:chemistry; D015967:Gene Expression Regulation, Viral / Q000187:drug effects*; D019288:Herpesvirus 8, Human / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D039823:Iridoids / Q000737:chemistry / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000378:metabolism; D060066:Protein Interaction Maps / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism; D012514:Sarcoma, Kaposi / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D017735:Virus Latency / Q000187:drug effects
chemical_list: D000956:Antigens, Viral; D000998:Antiviral Agents; D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D039823:Iridoids; D009687:Nuclear Proteins; D012097:Repressor Proteins; C109540:latency-associated nuclear antigen; C007834:genipin; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D020169:Caspases