Characterization of the antiviral activity of BCA2

描述(申请人提供)：BCA2(乳腺癌相关基因2，也称为RNF115、ZNF364或Rabring7)是一种环指E3泛素连接酶，在大多数乳腺癌细胞系中对雌激素的反应上调。最近的一项研究表明，BCA2与Tetherin的细胞质结构域相互作用，促进被拴住的HIV-1颗粒的内化和溶酶体降解，而BCA2的E3连接酶活性对于加强Tetherin介导的HIV-1的限制是必不可少的。因此，BCA2将作为Tetherin的辅助因子，在不表达Tetherin的细胞中缺乏抗病毒活性。然而，在这里，我们第一次证明，BCA2通过降低HIV-1 Gag的细胞水平，以一种不依赖于Tetherin的方式抑制病毒的产生，并且这一活动需要一个完整的环指结构域。此外，我们发现BCA2与GAG物理上相互作用，并促进其泛素化和溶酶体降解，表明BCA2可能是一种干扰病毒组装的先天抗病毒因子。我们希望通过表征BCA2抗病毒活性的分子机制(特异性目标1)和确定参与调控BCA2的S活性的分子，以及响应BCA2激活的细胞通路(特异性目标2)来正式解决这一假说。更好地了解限制病毒产生的先天机制将有助于制定抗逆转录病毒药物，以控制受影响个体的病毒复制。因此，这里概述的目标与确定抗逆转录病毒治疗控制HIV-1感染的新目标直接相关。

DESCRIPTION (provided by applicant): BCA2 (Breast Cancer-Associated gene 2, also known as RNF115, ZNF364 or Rabring7) is a RING-finger E3 ubiquitin ligase that is up-regulated 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, fo the first time, that BCA2 inhibits virus production in a tetherin-independent manner by reducing the cellular levels of HIV-1 Gag, and that this activity requires an intact RING-finger domain. Furthermore, we show that BCA2 physically interacts with Gag and promotes its ubiquitination and lysosomal degradation, suggesting that BCA2 may be an innate antiviral factor that interferes with 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 that participate in the regulation of BCA2's activity, as well as the cellular pathways that are activated in response to BCA2 (Specific Aim 2). A better understanding of the innate mechanisms that limit virus production will help in the elaboration of antiretroviral drugs o 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.