title: Extended stability of cyclin D1 contributes to limited cell cycle arrest at G1-phase in BHK-21 cells with Japanese encephalitis virus persistent infection.
abstract: There is increasing evidence that many RNA viruses manipulate cell cycle control to achieve favorable cellular environments for their efficient replication during infection. Although virus-induced G0/G1 arrest often delays early apoptosis temporarily, a prolonged replication of the infected virus leads host cells to eventual death. In contrast, most mammalian cells with RNA virus persistent infection often escape cytolysis in the presence of productive viral replication. In this study, we demonstrated that the extended endurance of cyclin D1 was clearly associated with the suppression of glycogen synthase kinase-3ß (GSK-3ß) expression in BHK-21 cells that are persistently infected with Japanese encephalitis virus (JEV). The G0/G1 arrest of these cells turned much loose compared to the normal BHK-21 cells with JEV acute infection. After cycloheximide treatment, cyclin D1 in the persistently infected cells lasted several hours longer than those in acutely infected cells. Furthermore, both p21(Cip1) and p27(Kip1), positive regulators for cyclin D1 accumulation in the nucleus, were suppressed in their expression, which contrasts with those in JEV acute infection. Inhibition of the GSK-3ß by lithium chloride treatment rescued a significant number of cells from cytolysis in JEV acute infection, which coincided with the levels of cyclin D1 that escaped from proteolysis. Therefore, the limitation of G1/S arrest in the BHK-21 cells with JEV persistent infection is associated with the suppression of GSK-3ß expression, resulting in the extended duration of cyclin D1.
authors.affiliation: Department of Biology and Research Institute of Basic Sciences, Kyung Hee University, Seoul, 130-701, Republic of Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Park
authors.forename: Hey Rhyoung
authors.initials: HR
authors.lastname: Lyoo
authors.forename: Eung Seo
authors.initials: ES
authors.lastname: Koo
authors.forename: Man Su
authors.initials: MS
authors.lastname: Kim
authors.forename: Yong Seok
authors.initials: YS
authors.lastname: Jeong
mesh_terms: D000818:Animals; D059447:Cell Cycle Checkpoints; D002455:Cell Division; D002460:Cell Line; D006224:Cricetinae; D019938:Cyclin D1 / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004261:DNA Replication; D004664:Encephalitis Virus, Japanese / Q000254:growth & development / Q000502:physiology*; D016193:G1 Phase; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics* / Q000378:metabolism; D018021:Lithium Chloride / Q000494:pharmacology; D055550:Protein Stability; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014779:Virus Replication
chemical_list: D011500:Protein Synthesis Inhibitors; D019938:Cyclin D1; D003513:Cycloheximide; D038362:Glycogen Synthase Kinase 3; D018021:Lithium Chloride