Cellular RelB interacts with the transactivator Tat and enhance HIV-1 expression

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Human immunodeficiency virus type 1 (HIV-1) Tat protein is crucial for viral gene transcription.
• Tat protein activates HIV-1 long terminal repeat (LTR)-directed gene expression via interactions with the transactivation-responsive region (TAR) element.
• Mechanisms of TAR-independent Tat-mediated LTR transactivation involving host factors are not fully understood.

Purpose of the Study:

• To investigate the role of host factors in TAR-independent Tat-mediated HIV-1 LTR transactivation.
• To elucidate the interaction between HIV-1 Tat protein and the host factor RelB.
• To determine the impact of RelB on HIV-1 gene transcription and viral replication.

Main Methods:

• Co-immunoprecipitation assays to detect interactions between Tat and RelB.
• Reporter assays to measure Tat-mediated HIV-1 LTR transactivation.
• Chromatin immunoprecipitation to assess the recruitment of Tat and RelB to the HIV-1 promoter.
• Quantitative reverse transcription PCR to measure viral gene expression and RNA polymerase II recruitment.

Main Results:

• RelB interacts with the core region of the HIV-1 Tat protein.
• RelB significantly enhances Tat-mediated transcription of the HIV-1 LTR and viral gene expression, independent of TAR.
• RelB facilitates Tat recruitment to the viral LTR promoter, with NF-κB elements being crucial for this accumulation.
• RelB knockout reduces RNA polymerase II accumulation on the LTR and decreases HIV-1 gene transcription.

Conclusions:

• RelB interacts with HIV-1 Tat protein and enhances TAR-independent activation of the HIV-1 LTR promoter.
• RelB contributes to HIV-1 transactivation, adding new insights into the complex mechanisms of Tat in regulating HIV-1 gene expression.