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Human immunodeficiency virus type 1 induction mediated by genistein is linked to cell cycle arrest in G2
J Gozlan1, J L Lathey, S A Spector
1Department of Pediatrics, University of California, San Diego, La Jolla, California, USA.
Abstract:
Protein tyrosine kinase (PTK) phosphorylation is involved in cellular proliferation and differentiation processes that are key factors for human immunodeficiency virus type 1 (HIV-1) regulation in infected monocytic cells. Short-term exposure of the chronically infected promyelocytic OM10 cell line with the PTK inhibitor genistein induced a dose-dependent increase in p24 antigen production in culture supernatants. This induction persisted in the presence of the reverse transcriptase inhibitor, zidovudine, and was associated with an increased transcription of HIV-1 multiply spliced and unspliced RNAs, suggesting a transcriptional mechanism targeting the integrated provirus. Genistein induced cell differentiation, apoptosis, and a G2 arrest in the OM10 cells. Cell differentiation and apoptosis were not directly involved in the observed increase in HIV-1 replication that was closely linked to genistein-induced G2 arrest. Alleviation of the G2 arrest by pentoxyfylline resulted in a concomitant reduction of HIV-1 to baseline replication. Additionally, by flow cytometry, a significant increase in the number of p24 antigen-expressing cells was observed in cells arrested in G2 compared to those located in G1 or S. Tyrosine kinase inhibition was found not to be essential for enhanced viral replication, which seemed to be related to two other properties of genistein, inhibition of topoisomerase II activity and inhibition of phosphotidylinositol turnover. These findings are consistent with the recent observation that HIV-1 Vpr induces viral replication through preventing proliferation of cells by arresting them in G2 of the cell cycle and strongly suggest that manipulation of the cell cycle plays an important role in HIV-1 pathogenesis.
Insights
Genistein, a protein tyrosine kinase inhibitor, increases HIV-1 replication by inducing G2 cell cycle arrest, not tyrosine kinase inhibition itself. This suggests cell cycle manipulation is key in HIV-1 pathogenesis.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Protein tyrosine kinase (PTK) phosphorylation regulates cellular processes critical for HIV-1 replication in monocytic cells.
- Understanding PTK roles is vital for developing novel HIV-1 therapeutic strategies.
Purpose of the Study:
- To investigate the effect of the PTK inhibitor genistein on HIV-1 replication in infected monocytic cells.
- To elucidate the mechanisms underlying genistein-induced changes in HIV-1 production and transcription.
Main Methods:
- Utilized the chronically infected promyelocytic OM10 cell line.
- Administered genistein and measured p24 antigen production and HIV-1 RNA transcription.
- Assessed cell cycle distribution (G1, G2, S phases) and apoptosis via flow cytometry.
- Investigated the roles of topoisomerase II and phosphotidylinositol turnover.
Main Results:
- Genistein treatment dose-dependently increased p24 antigen production and HIV-1 RNA transcription.
- HIV-1 replication increase was linked to genistein-induced G2 cell cycle arrest, not differentiation or apoptosis.
- Pentoxifylline alleviated G2 arrest, reducing HIV-1 replication.
- Increased p24 expression was observed in G2-arrested cells.
Conclusions:
- Genistein enhances HIV-1 replication primarily through G2 cell cycle arrest, independent of direct tyrosine kinase inhibition.
- Inhibition of topoisomerase II and phosphotidylinositol turnover may contribute to increased viral replication.
- Cell cycle manipulation, particularly G2 arrest, is a significant factor in HIV-1 pathogenesis and warrants further investigation for therapeutic interventions.