Characterization of the antiviral activity of BCA2

项目总结 BCA2(乳腺癌相关基因2，又称RNF115、ZNF364或Rabring7)是一种细胞质 环指E3泛素连接酶，在大多数乳腺癌细胞系中表达上调，对雌激素的反应。一个 最近的研究表明，BCA2与Tetherin的细胞质结构域相互作用，促进内化 BCA2的E3连接酶活性是必不可少的 以加强Tetherin介导的HIV-1的限制。因此，BCA2将作为Tetherin辅助因子， 在不表达Tetherin的细胞中缺乏抗病毒活性。然而，我们在这里展示了BCA2抑制病毒 通过降低HIV-1 GAG的细胞水平，以不依赖于Tetherin的方式生产，并且这一活动 需要E3连接酶活性。此外，我们还证明了BCA2与GAG在物理上相互作用，并促进其 泛素化，提示BCA2可能是一种先天的抗病毒因子，靶向GAG多聚蛋白 降解，从而阻碍病毒组装。我们希望通过描述以下特征来正式解决这一假设 BCA2抗病毒作用的分子机制(特异靶1)及其分子鉴定 参与调控Bca2‘S活性的细胞通路(特异性靶点2)。更好的 了解限制病毒产生的先天机制将有助于阐述抗逆转录病毒 在受影响的个体中抑制病毒复制的药物。因此，这里概述的目标直接 与确定抗逆转录病毒治疗的新目标有关，以控制艾滋病毒-1感染。

PROJECT SUMMARY BCA2 (Breast Cancer-Associated gene 2, also known as RNF115, ZNF364 or Rabring7) is a cytoplasmic RING-finger E3 ubiquitin ligase that is upregulated in most breast cancer cell lines in response to estrogen. A recent study showed that BCA2 interacts with the cytoplasmic domain of tetherin to promote the internalization and lysosomal degradation of tethered HIV-1 particles, and that the E3 ligase activity of BCA2 is dispensable to enhance the tetherin-mediated restriction of HIV-1. Therefore, BCA2 would act as a tetherin co-factor, lacking antiviral activity in cells that do not express tetherin. However, here we show that BCA2 inhibits virus production in a tetherin-independent manner by reducing the cellular levels of HIV-1 Gag, and that this activity requires the E3 ligase activity. Furthermore, we show that BCA2 physically interacts with Gag and promotes its ubiquitination, suggesting that BCA2 may be an innate antiviral factor that targets the Gag polyprotein for degradation, thereby, impeding virus assembly. We want to formally address this hypothesis by characterizing the molecular mechanisms of the antiviral activity of BCA2 (Specific Aim 1) and by identifying the molecules and cellular pathways that participate in the regulation of BCA2's activity (Specific Aim 2). A better understanding of the innate mechanisms that limit virus production will help in the elaboration of antiretroviral drugs to contain virus replication in affected individuals. Therefore, the objectives outlined here are directly relevant to identifying new targets for antiretroviral therapy to control HIV-1 infection.