Novel interactions between human T-cell leukemia virus type I Tax and activating transcription factor 3 at a cyclic AMP-responsive element.
Human proenkephalin gene transcription is transactivated by human T-cell leukemia virus type I (HTLV-I) Tax in human Jurkat T lymphocytes. This transactivation was further enhanced in Jurkat cells treated with concanavalin A, cyclic AMP, or 12-O-tetradecanoylphorbol-13-acetate. Deletion and cis-element transfer analyses of the human proenkephalin promoter identified a cyclic AMP-responsive AP-1 element (-92 to -86) as both necessary and sufficient to confer Tax-dependent transactivation. Different AP-1 or cyclic AMP-responsive element-binding protein (CREB)/activating transcription factor (ATF) proteins which bind this element were expressed in murine teratocarcinoma F9 cells to identify those capable of mediating Tax-dependent transactivation of human proenkephalin gene transcription. Although CREB, c-Fos, c-Jun, and JunD did not have significant effects, JunB inhibited the Tax-dependent transactivation. In contrast, ATF3 dramatically induced Tax-dependent transactivation, which was further enhanced by protein kinase A. Electrophoretic mobility shift assays with recombinant fusion proteins expressed and purified from bacteria indicate that the DNA-binding activity of ATF3 is also dramatically enhanced by Tax. Chimeric fusion proteins consisting of the DNA-binding domain of the yeast transcription factor Gal4 and the amino-terminal domain (residues 1 to 66) of ATF3 were able to mediate Tax-dependent transactivation of a Gal4-responsive promoter, which suggests a direct involvement of this region of ATF3. Recombinant fusion proteins of glutathione S-transferase with either the amino- or carboxy-terminal (residues 139 to 181) domain of ATF3 were able to specifically interact with Tax. Furthermore, specific antisera directed against Tax coimmunoprecipitated ATF3 only in the presence of Tax.
Low
K G
KG
Laboratory of Molecular Neurobiology, Massachusetts General Hospital, Charlestown 02129.
Chu
H M
HM
Schwartz
P M
PM
Daniels
G M
GM
Melner
M H
MH
Comb
M J
MJ
D051700:Activating Transcription Factor 3; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003208:Concanavalin A / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D017931:DNA Primers; D004742:Enhancer Elements, Genetic; D004745:Enkephalins / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli; D015870:Gene Expression; D016356:Gene Products, tax / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D013755:Tetradecanoylphorbol Acetate; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D051700:Activating Transcription Factor 3; D017931:DNA Primers; D004745:Enkephalins; D016356:Gene Products, tax; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C029992:proenkephalin; D003208:Concanavalin A; D000242:Cyclic AMP; D013755:Tetradecanoylphorbol Acetate