NEDDylation is essential for Kaposi's sarcoma-associated herpesvirus latency and lytic reactivation and represents a novel anti-KSHV target.
NEDDylation is essential for Kaposi's sarcoma-associated herpesvirus latency and lytic reactivation and represents a novel anti-KSHV target.
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DOI：
10.1371/journal.ppat.1004771
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发表时间：
2015-03
期刊：
影响因子：
6.7
通讯作者：
Whitehouse A
中科院分区：
文献类型：
--
作者：
Hughes DJ;Wood JJ;Jackson BR;Baquero-Pérez B;Whitehouse A
卡波西肉瘤相关疱疹病毒 (KSHV) 是卡波西肉瘤 (KS) 和原发性渗出性淋巴瘤 (PEL) 的病原体，这两种疾病与免疫功能低下患者相关的侵袭性恶性肿瘤。对于许多非病毒恶性肿瘤，针对泛素蛋白酶体系统（UPS）的治疗已取得成功。同样，实验室研究表明，抑制 UPS 可能为治疗 KSHV 相关疾病提供有希望的途径。 E3 泛素连接酶中最大的一类是 cullin-RING 连接酶 (CRL)，它由另一种泛素样蛋白 NEDD8 激活。我们发现，NEDDylation 的药理学抑制（使用小分子抑制剂 MLN4924）通过抑制 NF-κB 对 PEL 细胞具有细胞毒性。我们还表明，CRL4B 是一种新型的潜伏期调节因子，因为它的抑制作用重新激活了裂解基因的表达。此外，我们发现 KSHV 裂解周期重新激活期间需要 NEDDylation。有趣的是，抑制作用可以阻止病毒 DNA 复制，但不能阻止裂解周期相关基因的表达，这突显了一种将 KSHV 生物学的这两个特征分开的新机制。从机制上讲，我们表明 MLN4924 治疗阻止了病毒复制前复合物募集到裂解性 DNA 复制起点 (OriLyt)。这些新发现揭示了调节 KSHV 潜伏期和重新激活的新机制。此外，他们证明抑制 NEDDylation 代表了治疗 KSHV 相关恶性肿瘤的一种新方法。卡波西肉瘤相关疱疹病毒 (KSHV) 会导致卡波西肉瘤 (KS) 和原发性渗出性淋巴瘤 (PEL)，这两种疾病通常是折磨 HIV 感染者的致命恶性肿瘤。先前的研究表明，阻断泛素蛋白酶体系统（UPS，一种降解细胞蛋白质的正常质量控制途径）能够杀死 KSHV 感染的淋巴瘤细胞。 UPS 的一个重要组成部分是由称为 cullin-RING 泛素连接酶 (CRL) 的蛋白质家族组成，该家族由 NEDD8（称为 NEDDylation 的过程）激活。最近，一种NEDDylation抑制剂（MLN4924）被开发出来，目前作为抗癌药物正在进行临床试验。由于许多病毒的 NEDDylation 尚未得到研究，我们用它来综合检验其在 KSHV 生物学中的重要性。首先，我们证明 NEDDylation 对于 KSHV 感染的淋巴瘤细胞的生存能力至关重要，MLN4924 治疗通过阻断 NF-κB 活性（KSHV 潜伏基因表达和 KSHV 相关癌症所需）来杀死这些细胞。此外，我们发现 NEDdylation 是 KSHV 复制其基因组所必需的，这是产生新病毒颗粒的关键步骤。因此，这项研究确定了一种控制 KSHV 复制的新分子机制。此外，它表明 NEDDylation 是治疗 KSHV 相关恶性肿瘤的可行靶点。
Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), which are aggressive malignancies associated with immunocompromised patients. For many non-viral malignancies, therapeutically targeting the ubiquitin proteasome system (UPS) has been successful. Likewise, laboratory studies have demonstrated that inhibition of the UPS might provide a promising avenue for the treatment of KSHV-associated diseases. The largest class of E3 ubiquitin ligases are the cullin-RING ligases (CRLs) that are activated by an additional ubiquitin-like protein, NEDD8. We show that pharmacological inhibition of NEDDylation (using the small molecule inhibitor MLN4924) is cytotoxic to PEL cells by inhibiting NF-κB. We also show that CRL4B is a novel regulator of latency as its inhibition reactivated lytic gene expression. Furthermore, we uncovered a requirement for NEDDylation during the reactivation of the KSHV lytic cycle. Intriguingly, inhibition prevented viral DNA replication but not lytic cycle-associated gene expression, highlighting a novel mechanism that uncouples these two features of KSHV biology. Mechanistically, we show that MLN4924 treatment precluded the recruitment of the viral pre-replication complex to the origin of lytic DNA replication (OriLyt). These new findings have revealed novel mechanisms that regulate KSHV latency and reactivation. Moreover, they demonstrate that inhibition of NEDDylation represents a novel approach for the treatment of KSHV-associated malignancies. Kaposi’s sarcoma-associated herpesvirus (KSHV) causes Kaposi’s sarcoma (KS) and primary effusion lymphoma (PEL), often fatal malignancies afflicting HIV-infected patients. Previous research has shown that blockade of the ubiquitin proteasome system (UPS, a normal quality control pathway that degrades cellular proteins) is able to kill KSHV-infected lymphoma cells. A large component of the UPS is made up by the protein family known as the cullin-RING ubiquitin ligases (CRLs), which are activated by NEDD8 (a process known as NEDDylation). Recently, an inhibitor of NEDDylation (MLN4924) was developed and is currently in clinical trials as an anti-cancer drug. As NEDDylation has not been investigated for many viruses, we used this to compound examine its importance in KSHV biology. Firstly we show that NEDDylation is essential for the viability of KSHV-infected lymphoma cells, and MLN4924 treatment killed these cells by blocking NF-κB activity (required for KSHV latency gene expression and KSHV-associated cancer). Furthermore, we show that NEDDylation is required for KSHV to replicate its genome, a critical step in the production of new virus particles. Therefore, this research has identified a novel molecular mechanism that governs KSHV replication. Furthermore, it demonstrates that NEDDylation is a viable target for the treatment of KSHV-associated malignancies.
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