Latency-associated nuclear antigen encoded by Kaposi's sarcoma-associated herpesvirus interacts with tat and activates the long terminal repeat of human immunodeficiency virus type 1 in human cells
Latency-associated nuclear antigen encoded by Kaposi's sarcoma-associated herpesvirus interacts with tat and activates the long terminal repeat of human immunodeficiency virus type 1 in human cells
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DOI：
10.1128/jvi.75.18.8761-8771.2001
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发表时间：
2001-09-01
影响因子：
5.4
通讯作者：
Robertson, ES
中科院分区：
文献类型：
--
作者：
Hyun, TS;Subramanian, CA;Robertson, ES
潜伏相关核抗原（拉娜）在感染卡波西肉瘤（KS）疱疹病毒（KSHV）（也称为人疱疹病毒8）的细胞中组成型表达。KSHV与感染人类免疫缺陷病毒（HIV）的免疫功能低下患者的体腔淋巴瘤（BCBL）密切相关。拉娜由KSHV的开放阅读框73编码，是潜伏感染期间表达的蛋白质的一个小子集，并且被证明在将病毒附加体拴系到宿主染色体上方面是重要的。另外，已经显示拉娜可以作为转录调节子起作用。然而，其在疾病进展中的作用仍在阐明中。由于KS是美国最常见的艾滋病相关癌症之一，BCBL主要出现在艾滋病患者中，我们研究了拉娜是否能够调节HIV-1长末端重复序列（LTR）。使用基于内切酶的瞬时转染试验，我们发现拉娜能够反式激活人B细胞系BJAB、人单核细胞系U937和人胚肾成纤维细胞系293 T中的HIV-1 LTR。此外，我们观察到，病毒编码的HIV反式激活蛋白达特与拉娜合作，以剂量-反应方式激活LTR，增加拉娜的量。令人惊讶的是，单独的拉娜足以反式激活BJAB细胞中的HIV-1 LTR。在使用核心增强子元件缺失的HIV-1 LTR构建体的类似测定中，拉娜的活性降低但未消除，表明涉及核心增强子元件和下游元件（包括达特）的合作的机制。此外，用拉娜瞬时转染HIV感染性克隆显示出与基于HIV Gag多肽p24的Western印迹分析的报道基因测定中所见的效果相似的效果。有趣的是，我们还证明了拉娜的羧基末端在细胞和体外与达特相关。这些实验表明，拉娜通过与靶向核心增强子元件和达特的细胞分子结合而在激活HIV-1 LTR中发挥作用，并且可能在增加感染个体中的HIV水平以及因此增加疾病状态中具有重要后果。
The latency-associated nuclear antigen (LANA) is constitutively expressed in cells infected with the Kaposi's sarcoma (KS) herpesvirus (KSHV), also referred to as human herpesvirus 8. KSHV is tightly associated with body cavity-based lymphomas (BCBLs) in immunocompromised patients infected with human immunodeficiency virus (HIV). LANA, encoded by open reading frame 73 of KSHV, is one of a small subset of proteins expressed during latent infection and was shown to be important in tethering the viral episome to host chromosomes. Additionally, it has been shown that LANA can function as a regulator of transcription. However, its role in the progression of disease is still being elucidated. Since KS is one of the most common AIDS-associated cancers in the United States and BCBLs appear predominantly in AIDS patients, we examined whether LANA is able to regulate the HIV type 1 (HIV-1) long terminal repeat (LTR). Using luciferase-based transient transfection assays, we found that LANA was able to transactivate the HIV-1 LTR in the human B-cell line BJAB, human monocytic cell line U937, and the human embryonic kidney fibroblast cell line 293T. Moreover, we observed that the virus-encoded HIV transactivator protein Tat cooperated with LANA in activation of the LTR in a dose-response fashion with increasing amounts of LANA. Surprisingly, LANA alone was sufficient to transactivate the HIV-1 LTR in BJAB cells. In similar assays using a HIV-1 LTR construct with the core enhancer elements deleted; the activity of LANA was diminished but not abolished, indicating a mechanism which involves the cooperation of the core enhancer elements and downstream elements which include Tat. Furthermore, transient transfection of an infectious clone of HIV with LANA demonstrated effects similar to those seen in the reporter assays based on Western blot analysis of HIV Gag polypeptide p24. Interestingly, we also demonstrated that the carboxy terminus of LANA associates with Tat in cells and in vitro. These experiments suggest a role for LANA in activating the HIV-1 LTR through association with cellular molecules targeting the core enhancer elements and Tat and may have important consequences in increasing the levels of HIV in infected individuals and, hence, the disease state.