This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Li, J. Articles by He, J. J. Search for Related Content PubMed PubMed Citation Articles by Li, J. Articles by He, J. J.

 Previous Article  |  Next Article 

Journal of Virology, May 2002, p. 4526-4535, Vol. 76, No. 9
0022-538X/02/$04.00+0     DOI: 10.1128/JVI.76.9.4526-4535.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Expression of Exogenous Sam68, the 68-Kilodalton Src-Associated Protein in Mitosis, Is Able To Alleviate Impaired Rev Function in Astrocytes

Department of Microbiology and Immunology,¹ Walther Oncology Center,² Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202,⁴ Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, Harvard Medical School, Boston, Massachusetts 02115,³ Walther Cancer Institute, Indianapolis, Indiana 46208⁵

Received 8 November 2001/ Accepted 29 January 2002

Human immunodeficiency virus type 1 (HIV-1) gene expression in astrocytes is restricted, resulting in a brief and limited synthesis of HIV-1 viral structural proteins. Impaired Rev function has been documented in these cells. However, the molecular mechanisms underlying the impaired Rev function are not fully understood. Using the astroglial cell line U87.MG as a model, we report here that HIV-1 gene expression down-regulated expression of Sam68, the 68-kDa Src-associated protein in mitosis, which was constitutively expressed at a lower level in astrocytes. Elevating the endogenous level of Sam68 expression considerably restored HIV-1 Rev function in astrocytes, as determined by a Rev-dependent reporter gene assay. However, elevation of Sam68 expression achieved only a modest increase in HIV-1 production, further supporting the notion that there are multiple cellular restrictions of HIV-1 gene expression in astrocytes. Mutagenesis analysis identified the region between amino acids 321 and 410 of Sam68 as being directly involved in the binding of Sam68 to Rev, while a double mutation in Rev, L78D and E79L, like those in the dominant-negative Rev mutant M10, eliminated Rev binding to Sam68. Moreover, subcellular fractionation and digital fluorescence microscopic imaging revealed that Sam68 expression promoted Rev nuclear export. Taken together, our studies demonstrate that a lower level of constitutive Sam68 expression, followed by further down-regulation by HIV-1 infection, contributes to impaired Rev function in astrocytes, and they suggest that Sam68 may play an important role in Rev nuclear export.

This article has been cited by other articles:

• Carroll-Anzinger, D., Kumar, A., Adarichev, V., Kashanchi, F., Al-Harthi, L. (2007). Human Immunodeficiency Virus-Restricted Replication in Astrocytes and the Ability of Gamma Interferon To Modulate This Restriction Are Regulated by a Downstream Effector of the Wnt Signaling Pathway. J. Virol. 81: 5864-5871 [Abstract] [Full Text]  
• Lukong, K. E., Larocque, D., Tyner, A. L., Richard, S. (2005). Tyrosine Phosphorylation of Sam68 by Breast Tumor Kinase Regulates Intranuclear Localization and Cell Cycle Progression. J. Biol. Chem. 280: 38639-38647 [Abstract] [Full Text]  
• Ong, C. L., Thorpe, J. C., Gorry, P. R., Bannwarth, S., Jaworowski, A., Howard, J. L., Chung, S., Campbell, S., Christensen, H. S., Clerzius, G., Mouland, A. J., Gatignol, A., Purcell, D. F. J. (2005). Low TRBP Levels Support an Innate Human Immunodeficiency Virus Type 1 Resistance in Astrocytes by Enhancing the PKR Antiviral Response. J. Virol. 79: 12763-12772 [Abstract] [Full Text]  
• Modem, S., Badri, K. R., Holland, T. C., Reddy, T. R. (2005). Sam68 is absolutely required for Rev function and HIV-1 production. Nucleic Acids Res 33: 873-879 [Abstract] [Full Text]  
• Haegebarth, A., Heap, D., Bie, W., Derry, J. J., Richard, S., Tyner, A. L. (2004). The Nuclear Tyrosine Kinase BRK/Sik Phosphorylates and Inhibits the RNA-binding Activities of the Sam68-like Mammalian Proteins SLM-1 and SLM-2. J. Biol. Chem. 279: 54398-54404 [Abstract] [Full Text]  
• MCLAREN, M., ASAI, K., COCHRANE, A. (2004). A novel function for Sam68: Enhancement of HIV-1 RNA 3' end processing. RNA 10: 1119-1129 [Abstract] [Full Text]  
• Liu, Y., Liu, H., Kim, B. O., Gattone, V. H., Li, J., Nath, A., Blum, J., He, J. J. (2004). CD4-Independent Infection of Astrocytes by Human Immunodeficiency Virus Type 1: Requirement for the Human Mannose Receptor. J. Virol. 78: 4120-4133 [Abstract] [Full Text]  
• Radja, F., Kay, D. G., Albrecht, S., Jolicoeur, P. (2003). Oligodendrocyte-Specific Expression of Human Immunodeficiency Virus Type 1 Nef in Transgenic Mice Leads to Vacuolar Myelopathy and Alters Oligodendrocyte Phenotype In Vitro. J. Virol. 77: 11745-11753 [Abstract] [Full Text]  
• Li, J., Liu, Y., Kim, B. O., He, J. J. (2002). Direct Participation of Sam68, the 68-Kilodalton Src-Associated Protein in Mitosis, in the CRM1-Mediated Rev Nuclear Export Pathway. J. Virol. 76: 8374-8382 [Abstract] [Full Text]