Hematopoietic transcription factor GATA-2 activates transcription from HIV-1 long terminal repeat.
OBJECTIVE
To study the role of the hematopoietic transcription factor GATA-2 in long terminal repeat (LTR)-directed transcriptional activation of HIV-1 in hematopoietic progenitor cells, and to investigate possible GATA-2 binding sites in HIV-1 LTR.


METHODS
Wild-type HIV-1 LTR, or mutants, ligated to a luciferase reporter gene with or without a GATA-2 expression vector, were transfected into COS cells, and standardized luciferase activity was examined. The binding activity of GATA-2 to these sites was examined by electrophoretic mobility shift assay. These wild-type or mutant reporter genes were also transfected into the murine hematopoietic progenitor cells, BAF3, in which GATA-2 was the predominantly expressed transcription factor of the GATA family, to assay LTR-directed transcription in intact hematopoietic machinery. Using a Tat expression plasmid for cotransfection, the influence of Tat protein on GATA-2-induced transactivation was determined.


RESULTS
In COS cells, LTR-dependent transactivation was highly enhanced by the coexpression of GATA-2. Experiments with mutant LTR suggested the presence of multiple GATA-2 binding sites, of which the major sites were identified. Cotransfection of Tat with GATA-2 indicated that GATA-2 and Tat synergistically enhanced the transcriptional activity. Transfection experiments in BAF3 cells showed that the disruption of these GATA sites diminished LTR-driven activity to 40% of the wild-type.


CONCLUSIONS
GATA-2 may be a key host cell regulator of HIV-1 expression in hematopoietic stem cells. Manipulating this transactivation may represent a valuable approach to controlling virus production in infected hematopoietic progenitors. To elucidate the possible interaction between GATA-2 and Tat protein in vivo might give new insights to the mechanism of impaired hematopoiesis in AIDS patients.
Towatari
M
M
First Department of Internal Medicine, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Japan.
Kanei
Y
Y
Saito
H
H
Hamaguchi
M
M
D000818:Animals; D019556:COS Cells; D004268:DNA-Binding Proteins / Q000502:physiology*; D050989:GATA2 Transcription Factor; D015658:HIV Infections / Q000821:virology*; D016325:HIV Long Terminal Repeat / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000821:virology*; D006801:Humans; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation; D014779:Virus Replication / Q000502:physiology*
D004268:DNA-Binding Proteins; D050989:GATA2 Transcription Factor; C494711:GATA2 protein, human; D014157:Transcription Factors