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Towards dissecting the complexity of the AP-1 (Activator Protein 1) family

Unal, R
Weih, F
Schorle, H
Herrlich, P
The transcription factors called Activator Protein-1 (AP-1) collectively are dimers of two subunits derived from the Fos, Jun and ATF families1. Dimerization is mediated by the bzip domain of the subunits. For instance, cJun can dimerize with c-Fos or ATF-2. Each AP-1 dimer selects a closely related but distinct element in target promoters2,3. Nevertheless the function of these numerous AP-1 dimers is yet ill understood. One approach to dissecting the different roles has been chosen in overexpression studies: transfection or infection of c-Jun mutants whose dimerization interphase was altered such that their dimerization abilities are restricted. To explore the function of such restricted dimers in vivo, we prepared targeting vectors that could be used for insertional mutagenesis, that is replacement of the endogeneous gene by the mutant gene. In paralel we used c-Jun null murine fibroblasts to introduce the Jun expressing genes as expression constructs and tested their target promoter specificity.