HIV-1 Transcription Inhibition Using Small RNA-Binding Molecules.

Area of Science:

• Virology
• Molecular Biology
• Drug Discovery

Background:

• The HIV-1 transactivator protein Tat binds the transactivation response element (TAR) RNA to drive viral transcription.
• Targeting the Tat-TAR interaction is a key strategy for developing novel HIV-1 antiviral therapeutics.
• Current treatments do not specifically inhibit HIV-1 transcription, highlighting a therapeutic gap.

Purpose of the Study:

• To identify and characterize novel small molecules that inhibit HIV-1 transcription.
• To investigate the mechanism of action of these inhibitors on the Tat-TAR-P-TEFb complex and transcription factors.
• To assess the efficacy and safety of potential drug candidates in relevant cell models.

Main Methods:

• Identification of candidate inhibitors through screening.
• Molecular docking and simulation to analyze binding dynamics of small molecules with TAR RNA and P-TEFb.
• Biotinylated RNA pulldown assays for experimental validation.
• Assessment of effects on transcription factors like the SWI/SNF complex.
• Evaluation of viral transcription and protein expression in HIV-1 infected myeloid and T cells.

Main Results:

• Several candidate molecules were identified that inhibit HIV-1 transcription in myeloid and T cells with no apparent toxicity.
• Two molecules demonstrated significant inhibition of viral protein expression.
• Molecular simulations revealed binding interactions with TAR RNA and P-TEFb, with some candidates inducing conformational changes in the TAR RNA loop.
• Top candidates achieved substantial inhibition of viral transcription in primary HIV-1 infected cells.

Conclusions:

• Novel small molecules targeting HIV-1 transcription have been identified, offering a new therapeutic avenue.
• These inhibitors demonstrate potential to complement current combination antiretroviral therapy (cART) and address unmet needs.
• Targeting the TAR RNA loop and the Tat-binding site is crucial for developing effective HIV-1 transcription inhibitors.