Asunto(s)
Trasplante de Células Madre Hematopoyéticas , Herpesvirus Humano 4 , Células Asesinas Naturales/virología , Trastornos Linfoproliferativos/terapia , Linfocitos T/virología , Adulto , Proliferación Celular , Femenino , Humanos , Trastornos Linfoproliferativos/virología , Masculino , Persona de Mediana Edad , Pronóstico , Inducción de Remisión , Factores de Tiempo , Acondicionamiento Pretrasplante , Resultado del Tratamiento , Adulto JovenAsunto(s)
Antineoplásicos/administración & dosificación , Donantes de Sangre , Trasplante de Médula Ósea , Infecciones por Virus de Epstein-Barr/terapia , Herpesvirus Humano 4 , Transfusión de Linfocitos , Trastornos Linfoproliferativos/terapia , Anticuerpos Monoclonales de Origen Murino , Humanos , Trastornos Linfoproliferativos/virología , Masculino , Persona de Mediana Edad , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Rituximab , Factores de Tiempo , Trasplante HomólogoRESUMEN
Latent Epstein-Barr virus (EBV) is maintained by the virus replication origin oriP that initiates DNA replication with the viral oriP-binding factor EBNA1. However, it is not known whether oriP's replicator activity is regulated by virus proteins or extracellular signals. By using a transient replication assay, we found that a low level of expression of viral signal transduction activator latent membrane protein 1 (LMP1) suppressed oriP activity. The binding site of the tumor necrosis factor receptor-associated factor (TRAF) of LMP1 was essential for this suppressive effect. Activation of the TRAF signal cascade by overexpression of TRAF5 and/or TRAF6 also suppressed oriP activity. Conversely, blocking of TRAF signaling with dominant negative mutants of TRAF5 and TRAF6, as well as inhibition of a downstream signal mediator p38 MAPK, released the LMP1-induced oriP suppression. Furthermore, activation of TRAF6 signal cascade by lipopolysaccharides (LPS) resulted in loss of EBV from Burkitt's lymphoma cell line Akata, and inhibition of p38 MAPK abolished the suppressive effect of LPS. These results suggested that the level of oriP activity is regulated by LMP1 and extracellular signals through TRAF5- and TRAF6-mediated signal cascades.
Asunto(s)
Herpesvirus Humano 4/fisiología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Proteínas/metabolismo , Proteínas de la Matriz Viral/metabolismo , Sitios de Unión , Linfoma de Burkitt , Cápside , Línea Celular Transformada , Replicación del ADN , Regulación hacia Abajo , Células HeLa , Herpesvirus Humano 4/genética , Humanos , Lipopolisacáridos/farmacología , Mutación , Plásmidos , Transducción de Señal/efectos de los fármacos , Factor 5 Asociado a Receptor de TNF , Factor 6 Asociado a Receptor de TNF , Proteínas de la Matriz Viral/genética , Latencia del Virus , Replicación Viral , Proteínas Quinasas p38 Activadas por MitógenosRESUMEN
Latent Epstein-Barr virus genome is maintained in cells by the viral oriP-binding factor EBNA1 and cellular replication factors. EBNA1 binds to the dyad symmetry (DS) element in oriP and initiates DNA replication once in a single S phase, but the mechanism by which this DS-dependent replication is initiated is unknown. Replication licensing of cellular chromatins occurs during early G1 phase. Because licensing is essential for the next round of replication in S phase, it facilitates once-in-a-cell-cycle replication of the cellular genome. Using the transient replication assay with HeLa/EB1 cell, we demonstrate that the oriP plasmid required a cell cycle window including early G1 phase for replication in the next S phase. The plasmid containing only the DS element had a similar requirement of early G1 phase for replication. Analysis using sucrose density gradient centrifugation revealed that the oriP minichromosome existed in two distinct states: one formed at late G1 and the other formed at G2/M. These results suggest that the DS-dependent DNA replication from oriP requires the replication licensing, implying a possible involvement of the cellular licensing factor MCM in the DNA replication from oriP.