Mechanism of action of a dominant negative c-jun mutant in inhibiting activator protein-1 activation.
The dominant negative c-jun TAM-67 has been shown to inhibit tumor promotion induced by 12-O-tetradecanoylphorbol-13-acetate and okadaic acid (OA). To better understand this phenomenon, we investigated the mechanism of action of TAM-67 in response to OA. To identify the mechanism of action, we used a 6xHis-tagged TAM-67 as well as chimeric constructs of TAM-67 that either cannot bind DNA or cannot heterodimerize with wild-type transcription factors. The results of these studies indicated that TAM-67 acts by blocking or squelching. The results of elecrophoretic mobility-shift assays showed that TAM-67 must act by squelching in response to OA, as TAM-67 cannot be found in DNA-binding complexes. We then identified some of the proteins with which TAM-67 interacts. They include all members of the jun and fos families as well as the cAMP response element binding protein, activating transcription factor-1, activating transcription factor-2, and RelA (p65). Thus, we have shown that TAM-67 squelches the induction of activating transcription factor-1 transactivation in response to OA and that TAM-67 is capable of interacting with proteins that control transactivation by binding to the 12-O-tetradecanoylphorbol-13-acetate response element, cAMP response element and nuclear factor-kappaB sites.
Thompson
Eric J
EJ
Department of Pharmacology and Toxicology, The University of Arizona, Tucson, USA.
Gupta
Ashok
A
Stratton
M Suzanne
MS
Bowden
G Tim
GT
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D005799:Genes, Dominant; D051379:Mice; D009154:Mutation; D011233:Precipitin Tests; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics*; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism
D017931:DNA Primers; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1