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.

Public Health Relevance

The studies outlined in this proposal are expected to reveal the molecular mechanism by which BCA2, a cytoplasmic E3 ubiquitin ligase, inhibits HIV-1 replication. Furthermore, we seek to understand the response elements and cellular pathways that regulate the antiviral activity of BCA2, which will help develop new antiretroviral drugs to contain HIV-1 replication.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
7R21AI106400-02
Application #
8926085
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Sanders, Brigitte E
Project Start
2014-04-01
Project End
2016-03-31
Budget Start
2014-09-01
Budget End
2015-03-31
Support Year
2
Fiscal Year
2014
Total Cost
$191,748
Indirect Cost
$53,192
Name
Texas Tech University
Department
Type
DUNS #
041367053
City
Lubbock
State
TX
Country
United States
Zip Code
79409
Serra-Moreno, Ruth (2014) The end of Nef's tether. Trends Microbiol 22:662-4
Nityanandam, Ramya; Serra-Moreno, Ruth (2014) BCA2/Rabring7 targets HIV-1 Gag for lysosomal degradation in a tetherin-independent manner. PLoS Pathog 10:e1004151