Jun and Fos Heterodimerize with ATFa, a Member of the ATF/CREB Family and Modulate Its Transcriptional Activity

CHATTON B.; BOCCO J.L.; GOETZ J.; GAIRE M.; LUTZ Y.; KEDINGER C.

NATURE PUBLISHING GROUP

Lugar: Londres; Año: 1994 vol. 9 p. 375 - 375

hree related clones encoding proteins (ATFa1, 2 and 3) with specific ATF/CRE DNA-binding activities have been isolated from HeLa cell cDNA libraries. All three isoforms have weak effects on the basal activity of the adenovirus E2a promoter. We present evidence suggesting that a C-terminal element of the ATFa molecules negatively interferes with the intrinsic activation function of these proteins. We also show that coexpression of ATFa with c-Jun, Jun-B or Jun-D stimulates ATFa-dependent reporter activity, while coexpression of c-Fos has no effect. Deletion analyses indicate that the metal-binding region of ATFa is dispensible for this effect, but that the domain comprising the leucine-zipper region of ATFa is required. Reciprocal co-immunoprecipitation experiments and electrophoretic band-shift assays with in vitro synthesized proteins reveal direct interactions between ATFa and Jun or Fos. The ATFa/c-Jun heterodimers, but not the ATFa/c-Fos complexes, bind efficiently to ATF, CRE or