Datta Antara, Silverman Lee, Phipps Andrew J, Hiraragi Hajime, Ratner Lee, Lairmore Michael D
Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA.
Retrovirology. 2007 Jul 16;4:49. doi: 10.1186/1742-4690-4-49.
Human T-lymphotropic virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma and is linked to a number of lymphocyte-mediated disorders. HTLV-1 contains both regulatory and accessory genes in four pX open reading frames. pX ORF-II encodes two proteins, p13 and p30, whose roles are still being defined in the virus life cycle and in HTLV-1 virus-host cell interactions. Proviral clones of HTLV-1 with pX ORF-II mutations diminish the ability of the virus to maintain viral loads in vivo. p30 expressed exogenously differentially modulates CREB and Tax-responsive element-mediated transcription through its interaction with CREB-binding protein/p300 and while acting as a repressor of many genes including Tax, in part by blocking tax/rex RNA nuclear export, selectively enhances key gene pathways involved in T-cell signaling/activation.
Herein, we analyzed the role of p30 in cell cycle regulation. Jurkat T-cells transduced with a p30 expressing lentivirus vector accumulated in the G2-M phase of cell cycle. We then analyzed key proteins involved in G2-M checkpoint activation. p30 expression in Jurkat T-cells resulted in an increase in phosphorylation at serine 216 of nuclear cell division cycle 25C (Cdc25C), had enhanced checkpoint kinase 1 (Chk1) serine 345 phosphorylation, reduced expression of polo-like kinase 1 (PLK1), diminished phosphorylation of PLK1 at tyrosine 210 and reduced phosphorylation of Cdc25C at serine 198. Finally, primary human lymphocyte derived cell lines immortalized by a HTLV-1 proviral clone defective in p30 expression were more susceptible to camptothecin induced apoptosis. Collectively these data are consistent with a cell survival role of p30 against genotoxic insults to HTLV-1 infected lymphocytes.
Collectively, our data are the first to indicate that HTLV-1 p30 expression results in activation of the G2-M cell cycle checkpoint, events that would promote early viral spread and T-cell survival.
人类嗜T淋巴细胞病毒1型（HTLV-1）可引发成人T细胞白血病/淋巴瘤，并与多种淋巴细胞介导的疾病相关。HTLV-1在四个pX开放阅读框中同时包含调节基因和辅助基因。pX ORF-II编码两种蛋白，即p13和p30，它们在病毒生命周期以及HTLV-1病毒与宿主细胞相互作用中的作用仍有待明确。携带pX ORF-II突变的HTLV-1前病毒克隆会降低病毒在体内维持病毒载量的能力。外源表达的p30通过与CREB结合蛋白/p300相互作用，对CREB和Tax反应元件介导的转录进行差异调节，并且在作为包括Tax在内的许多基因的阻遏物时，部分通过阻断tax/rex RNA核输出，选择性增强参与T细胞信号传导/激活的关键基因途径。
在此，我们分析了p30在细胞周期调控中的作用。用表达p30的慢病毒载体转导的Jurkat T细胞在细胞周期的G2-M期积累。然后，我们分析了参与G2-M期检查点激活的关键蛋白。Jurkat T细胞中p30的表达导致核细胞分裂周期2蛋白5C（Cdc25C）的丝氨酸216磷酸化增加，检查点激酶1（Chk1）的丝氨酸345磷酸化增强，polo样激酶1（PLK1）的表达降低，PLK1的酪氨酸210磷酸化减少，以及Cdc25C的丝氨酸198磷酸化减少。最后，由p30表达缺陷的HTLV-1前病毒克隆永生化的原代人淋巴细胞系对喜树碱诱导的凋亡更敏感。总体而言，这些数据与p30在抵抗HTLV-1感染淋巴细胞的基因毒性损伤中发挥细胞存活作用一致。
总体而言，我们的数据首次表明HTLV-1 p30的表达导致G2-M期细胞周期检查点的激活，这些事件将促进病毒早期传播和T细胞存活。
