Identification of a Non-Nucleoside Reverse Transcriptase Inhibitor against Human Immunodeficiency Virus-1.

The HIV-1 infection epidemic remains a global health problem. Current antiretroviral treatments are effective in controlling the progression of a severe infection. However, the emergence of drug resistance requires an urgent identification of new treatment regimes.

A Novel Time-Resolved Fluorescence Resonance Energy Transfer Assay for the Discovery of Small-Molecule Inhibitors of HIV-1 Tat-Regulated Transcription.

Human immunodeficiency virus-1 (HIV-1) transactivator (Tat)-mediated transcription is essential for HIV-1 replication. It is determined by the interaction between Tat and transactivation response (TAR) RNA, a highly conserved process representing a prominent therapeutic target against HIV-1 replication. However, owing to the limitations of current high-throughput screening (HTS) assays, no drug that disrupts the Tat-TAR RNA interaction has been uncovered yet.

Investigation of the effect of SRSF9 overexpression on HIV-1 production.

Serine-arginine-rich splicing factors (SRSFs) are members of RNA processing proteins in the serine-arginine-rich (SR) family that could regulate the alternative splicing of the human immunodeficiency virus-1 (HIV-1). Whether SRSF9 has any effect on HIV-1 regulation requires elucidation. Here, we report for the first time the effects and mechanisms of SRSF9 on HIV-1 regulation.

Identification of Novel Nucleocapsid Chimeric Proteins Inhibiting HIV-1 Replication.

The positive transcription elongation factor b (P-TEFb) is an essential factor that induces transcription elongation and is also negatively regulated by the cellular factor HEXIM1. Previously, the chimeric protein HEXIM1-Tat (HT) was demonstrated to inhibit human immunodeficiency virus-1 (HIV)-1 transcription. In this study, we attempted to develop an improved antiviral protein that specifically binds viral RNA (vRNA) by fusing HT to HIV-1 nucleocapsid (NC).

Investigation of the effect of Staufen1 overexpression on the HIV-1 virus production.

In this study, we investigated how Staufen1 influences the HIV-1 production. The overexpression of Staufen1 increased virus production without any negative affect on the viral infectivity. This increase was not caused by transcriptional activation; but by influencing post-transcriptional steps.

Human transcription factor YY1 could upregulate the HIV-1 gene expression.

Gene expression in HIV-1 is regulated by the promoters in 5' long-terminal repeat (LTR) element, which contain multiple DNA regulatory elements that serve as binding sites for cellular transcription factors. YY1 could repress HIV-1 gene expression and latent infection. Here, however, we observed that virus production can be increased by YY1 over-expression and decreased under YY1 depleted condition by siRNA treatment.

Understanding of the functional role(s) of the Activating Transcription Factor 4(ATF4) in HIV regulation and production.

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown.

Investigation of functional roles of transcription termination factor-1 (TTF-I) in HIV-1 replication.

Transcription termination factor-1 (TTF-I) is an RNA polymerase 1-mediated transcription terminator and consisting of a C-terminal DNA-binding domain, central domain, and N-terminal regulatory domain. This protein binds to a so-called 'Sal box' composed of an 11-base pair motif. The interaction of TTF-I with the 'Sal box' is important for many cellular events, including efficient termination of RNA polymerase-1 activity involved in pre-rRNA synthesis and formation of a chromatin loop.

Investigation of function and regulation of the YB-1 cellular factor in HIV replication.

Y-box binding protein 1 (YB-1) is a member of the cold-shock domain (CSD) protein superfamily. It participates in a wide variety of cellular events, including transcription, RNA splicing, translation, DNA repair, drug resistance, and stress responses. We investigated putative functions of YB-1 in HIV-1 replication.

HIV-1 nucleocapsid protein localizes efficiently to the nucleus and nucleolus.

The HIV-1 nucleocapsid (NC) is an essential viral protein containing two highly conserved retroviral-type zinc finger (ZF) motifs, which functions in multiple stages of the HIV-1 life cycle. Although a number of functions for NC either in its mature form or as a domain of Gag have been revealed, little is known about the intracellular localization of NC and, moreover, its role in Gag protein trafficking. Here, we have investigated various forms of HIV-1 NC protein for its cellular localization and found that the NC has a strong nuclear and nucleolar localization activity.

Identification and characterization of a new type of inhibitor against the human immunodeficiency virus type-1 nucleocapsid protein.

Background: The human immunodeficiency virus type-1 (HIV-1) nucleocapsid protein (NC) is an essential and multifunctional protein involved in multiple stages of the viral life cycle such as reverse transcription, integration of proviral DNA, and especially genome RNA packaging. For this reason, it has been considered as an attractive target for the development of new anti-HIV drugs. Although a number of inhibitors of NC have been reported thus far, the search for NC-specific and functional inhibitor(s) with a good antiviral activity continues.

Development of a functional cell-based assay that probes the specific interaction between influenza A virus NP and its packaging signal sequence RNA.

Although cis-acting packaging signal RNA sequences for the influenza virus NP encoding vRNA have been identified recently though genetic studies, little is known about the interaction between NP and the vRNA packaging signals either in vivo or in vitro. Here, we provide evidence that NP is able to interact specifically with the vRNA packaging sequence RNA within living cells and that the specific RNA binding activity of NP in vivo requires both the N-terminal and central region of the protein. This assay established would be a valuable tool for further detailed studies of the NP-packaging signal RNA interaction in living cells.

Identification of a novel type of small molecule inhibitor against HIV-1.

Here we report a new chemical inhibitor against HIV-1 with a novel structure and mode of action. The inhibitor, designated as A1836, inhibited HIV-1 replication and virus production with a 50% inhibitory concentration (IC₅₀) of 2.0 μM in an MT-4 cell-based and cytopathic protection antiviral assay, while its 50% cytotoxic concentration (CC₅₀) was much higher than 50 μM.

The HIV-1 nucleocapsid protein does not function as a transcriptional activator on its own cognate promoter.

The human immunodeficiency virus type 1 (HIV-1) nucleocapsid (NC) is a multifunctional, zinc finger-containing protein known to be involved in almost every step of the viral life cycle. We therefore examined the effects of NC in vivo as a transcription activator on the basal transcriptional activity of the HIV-1 U3 and Rous sarcoma virus (RSV) promoters, as well as HIV-1 long terminal repeats (LTRs) such as the U3R and U3RU5 regions, using promoter-fused reporter gene assays, Western blot analyses, and quantitative real time-polymerase chain reaction. From these studies, we found that the basal transcriptional levels of the HIV-1 U3 and RSV promoters were barely enhanced by the presence of NC.

Identification of in vivo interaction between Hepatitis C Virus core protein and 5' and 3' UTR RNA.

Here, we investigated the ability of the Hepatitis C Virus (HCV) core protein to interact specifically with the 5' and 3' untranslated regions (UTRs) of HCV using an in vivo cell-based translation inhibition assay. HCV core protein interacts weakly but specifically with the SLIII stem loop in the 5' UTR in which the SLIIIb subdomain is the major determinant and the SL2 loop in the X region of the 3' UTR. These results revealed for the first time in vivo interaction of the core protein with 5' and 3' UTRs involved in the viral life cycle.