AEGiS-08IAC: The role of cellular cofactors in Tat-mediated trans-activation.

8th International AIDS Conference


Amsterdam, Netherlands — July 19-24, 1992

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The role of cellular cofactors in Tat-mediated trans-activation.

Int Conf AIDS 1992 Jul 19-24; 8:We46 (abstract no. WeA 1007)
Shank PR, Newstein M, Lee I; Brown University Division of Biology and Medicine, Providence, RI.

OBJECTIVES: We wished to define the role of various cellular cofactors which interact with the Tat protein and the TAR region in the process of trans-activation.

METHODS: We have used transient transfection assays of various LTR driven reporter plasmids along with Tat expression vectors into rodent cells. Rodents are generally refractory to trans-activation (Hart et al., Science 246:488-491, 1989; Newstein et al., J. Virol. 64:4564-4567, 1990). We have utilized the chimeric trans-activation system developed by Selby and Peterlin (Cell 62:769-776, 1990) and various mutations of the TAR region to define the role of cellular cofactors.

RESULTS: We find that the chimeric trans-activation system in which Tat protein is artificially tethered near the 5' end of the HIV transcript, by replacing the TAR region with a heterologous RNA recognition site, is not responsive in rodent cells. If however chimeric Tat is artificially tethered to the TAR region in constructs in which the normal Tat binding "bulge" has been replaced by the heterologous RNA recognition site, trans-activation occurs efficiently in rodent cells. Furthermore if mutations, which would inactivate wild-type trans-activation are introduced into the TAR "loop" region into these constructs the level of trans-activation increases in both rodent and human cells.

CONCLUSIONS: Our results suggest that the restriction to Tat-mediated trans-activation in rodent cells can be overcome by artificially tethering the functional domain of Tat to near the 5' end of the HIV transcripts if the basic "stem" structure of TAR is retained. We assume that factors binding to the TAR "stem" region are essential for efficient trans-activation.

Keywords: AEGIS, Gene Products, tat, Antithrombin III, Peptide Hydrolases, RNA, RNA Polymerase II, RNA-Binding Proteins, Hela Cells, Cells, antithrombin III-protease complex, Human, ICA8KWDaegis,geneproducts,tat,antithrombiniii,peptidehydrolases,rna,rnapolymeraseii,rna-bindingproteins,helacells,cells,antithrombiniii-proteasecomplex,human,ica8
920719
WeA1007

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