Chen J, Ueda K, Sakakibara S, Okuno T, Parravicini C, Corbellino M, Yamanishi K
Department of Microbiology, Osaka University Medical School, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):4119-24. doi: 10.1073/pnas.051004198.
Kaposi's sarcoma-associated herpesvirus (KSHV) is strongly linked to Kaposi's sarcoma, primary effusion lymphomas, and a subset of multicentric Castleman's disease. The mechanism by which this virus establishes latency and reactivation is unknown. KSHV Lyta (lytic transactivator, also named KSHV/Rta), mainly encoded by the ORF 50 gene, is a lytic switch gene for viral reactivation from latency, inasmuch as it is both essential and sufficient to drive the entire viral lytic cycle. Here we show that the Lyta promoter region was heavily methylated in latently infected cells. Treatment of primary effusion lymphoma-delivered cell lines with tetradecanoylphorbol acetate caused demethylation of the Lyta promoter and induced KSHV lytic phase in vitro. Methylation cassette assay shows demethylation of the Lyta promoter region was essential for the expression of Lyta. In vivo, biopsy samples obtained from patients with KSHV-related diseases show the most demethylation in the Lyta promoter region, whereas samples from a latently infected KSHV carrier remained in a methylated status. These results suggest a relationship among a demethylation status in the Lyta promoter, the reactivation of KSHV, and the development of KSHV-associated diseases.
卡波西肉瘤相关疱疹病毒（KSHV）与卡波西肉瘤、原发性渗出性淋巴瘤以及多中心性Castleman病的一个亚型密切相关。该病毒建立潜伏和再激活的机制尚不清楚。KSHV Lyta（裂解反式激活因子，也称为KSHV/Rta）主要由ORF 50基因编码，是病毒从潜伏状态再激活的裂解开关基因，因为它对于驱动整个病毒裂解周期既是必需的也是充分的。在此我们表明，Lyta启动子区域在潜伏感染细胞中高度甲基化。用十四酰佛波醇乙酸酯处理原发性渗出性淋巴瘤衍生的细胞系可导致Lyta启动子去甲基化并在体外诱导KSHV裂解期。甲基化盒分析表明，Lyta启动子区域的去甲基化对于Lyta的表达至关重要。在体内，从KSHV相关疾病患者获得的活检样本显示Lyta启动子区域去甲基化程度最高，而来自潜伏感染KSHV携带者的样本则保持甲基化状态。这些结果表明Lyta启动子的去甲基化状态、KSHV的再激活以及KSHV相关疾病的发生之间存在关联。
