New insights into the control of HIV-1 transcription: when Tat meets the 7SK snRNP and super elongation complex (SEC).

Abstract

Recent studies aimed at elucidating the mechanism controlling HIV-1 transcription have led to the identification and characterization of two multi-subunit complexes that both contain P-TEFb, a human transcription elongation factor and co-factor for activation of HIV-1 gene expression by the viral Tat protein. The first complex, termed the 7SK snRNP, acts as a reservoir where active P-TEFb can be withdrawn by Tat to stimulate HIV-1 transcription. The second complex, termed the super elongation complex (SEC), represents the form of P-TEFb delivered by Tat to the paused RNA polymerase II at the viral long terminal repeat during Tat transactivation. Besides P-TEFb, SEC also contains other elongation factors/co-activators, and they cooperatively stimulate HIV-1 transcription. Recent data also indicate SEC as a target for the mixed lineage leukemia (MLL) protein to promote the expression of MLL target genes and leukemogenesis. Given their roles in HIV-1/AIDS and cancer, further characterization of 7SK snRNP and SEC will help develop strategies to suppress aberrant transcriptional elongation caused by uncontrolled P-TEFb activation. As both complexes are also important for normal cellular gene expression, studying their structures and functions will elucidate the mechanisms that control metazoan transcriptional elongation in general.

• Authors: Nanhai He, Qiang Zhou
• Journal: Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology (J Neuroimmune Pharmacol) Vol. 6 Issue 2 Pg. 260-8 (Jun 2011) ISSN: 1557-1904 [Electronic] United States
• PMID: 21360054 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Review)

Chemical References

• Ribonucleoproteins, Small Nuclear
• tat Gene Products, Human Immunodeficiency Virus
• Positive Transcriptional Elongation Factor B

Topics

• Animals
• HIV-1 (genetics, metabolism)
• Humans
• Positive Transcriptional Elongation Factor B (genetics, metabolism)
• Ribonucleoproteins, Small Nuclear (genetics, metabolism)
• Transcription, Genetic (physiology)
• tat Gene Products, Human Immunodeficiency Virus (genetics, metabolism)