Role of the HIV-1 positive elongation factor P-TEFb and inhibitors thereof.

Transcription is considered to be a crucial step in the replication cycle of HIV-1. Tat regulates an early step of transcription elongation. The positive elongation factor P-TEFb, a heterodimer containing a catalytic subunit (CDK9) and unique regulatory cyclins (CycT1), is required for HIV-1 Tat transcriptional activation. This is a potential target for new HIV-1 transcription inhibitors. Without P-TEFb, transactivation is restrained and only short transcripts are generated. All the P-TEFb inhibitors can suppress the HIV-1 transactivation process by inhibition of CycT1, CDK9 or their interaction. Several low-molecular-weight compounds such as flavopiridol, roscovitine and the human small nuclear RNA 7SK which have been showed to possess potent anti-HIV activity by interfering with P-TEFb functions are reviewed in this article.