Journal article
Inhibition of HIV-1 replication by P-TEFb inhibitors DRB, seliciclib and flavopiridol correlates with release of free P-TEFb from the large, inactive form of the complex
Retrovirology, Vol.4(1), pp.47-47
07/11/2007
DOI: 10.1186/1742-4690-4-47
PMCID: PMC1948018
PMID: 17625008
Abstract
Background: The positive transcription elongation factor, P-TEFb, comprised of cyclin dependent kinase 9 (Cdk9) and cyclin T1, T2 or K regulates the productive elongation phase of RNA polymerase II (Pol II) dependent transcription of cellular and integrated viral genes. P-TEFb containing cyclin T1 is recruited to the HIV long terminal repeat (LTR) by binding to HIV Tat which in turn binds to the nascent HIV transcript. Within the cell, P-TEFb exists as a kinase-active, free form and a larger, kinase-inactive form that is believed to serve as a reservoir for the smaller form.
Results: We developed a method to rapidly quantitate the relative amounts of the two forms based on differential nuclear extraction. Using this technique, we found that titration of the P-TEFb inhibitors flavopiridol, DRB and seliciclib onto HeLa cells that support HIV replication led to a dose dependent loss of the large form of P-TEFb. Importantly, the reduction in the large form correlated with a reduction in HIV-1 replication such that when 50% of the large form was gone, HIV-1 replication was reduced by 50%. Some of the compounds were able to effectively block HIV replication without having a significant impact on cell viability. The most effective P-TEFb inhibitor flavopiridol was evaluated against HIV-1 in the physiologically relevant cell types, peripheral blood lymphocytes (PBLs) and monocyte derived macrophages (MDMs). Flavopiridol was found to have a smaller therapeutic index (LD50/IC50) in long term HIV-1 infectivity studies in primary cells due to greater cytotoxicity and reduced efficacy at blocking HIV-1 replication.
Conclusion: Initial short term studies with P-TEFb inhibitors demonstrated a dose dependent loss of the large form of P-TEFb within the cell and a concomitant reduction in HIV-1 infectivity without significant cytotoxicity. These findings suggested that inhibitors of P-TEFb may serve as effective anti-HIV-1 therapies. However, longer term HIV-1 replication studies indicated that these inhibitors were more cytotoxic and less efficacious against HIV-1 in the primary cell cultures.
Details
- Title: Subtitle
- Inhibition of HIV-1 replication by P-TEFb inhibitors DRB, seliciclib and flavopiridol correlates with release of free P-TEFb from the large, inactive form of the complex
- Creators
- Sebastian Biglione - Interdisciplinary Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA, USASarah A Byers - Interdisciplinary Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA, USAJason P Price - Department of Microbiology, University of Iowa, Iowa City, IA, USAVan Trung Nguyen - Laboratoire de Regulation de l'Expression Genetique, Ecole Normale Superieure, Paris, FranceOlivier Bensaude - Laboratoire de Regulation de l'Expression Genetique, Ecole Normale Superieure, Paris, FranceDavid H Price - Interdisciplinary Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA, USAWendy Maury - Interdisciplinary Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA, USA
- Resource Type
- Journal article
- Publication Details
- Retrovirology, Vol.4(1), pp.47-47
- DOI
- 10.1186/1742-4690-4-47
- PMID
- 17625008
- PMCID
- PMC1948018
- NLM abbreviation
- Retrovirology
- ISSN
- 1742-4690
- eISSN
- 1742-4690
- Publisher
- BioMed Central; London
- Language
- English
- Date published
- 07/11/2007
- Academic Unit
- Microbiology and Immunology; Biochemistry and Molecular Biology
- Record Identifier
- 9984024534602771
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