The Ets transcription factors interact with each other and with the c-Fos/c-Jun complex via distinct protein domains in a DNA-dependent and -independent manner

The transcription factors Fos,Jun, and Ets regulate the expression of human stromelysin-1 and collagenase-1 genes, Recently, we found that ERG, an Ets family member, activates collagenase-1 gene but not stromely-sin-1 by physically interacting with c-Fos/c-Jun, Interestingly, ERG binds to stromelysin-1 promoter and represses its activation by ETS2. Here, to investigate the molecular mechanism of this regulation, we have used an in vitro protein-protein interaction assay and studied the transcription factor interactions of ETS2. We found that ETS2 could weakly associate with in vitro synthesized ETS1, c-Fos, and c-Jun and strongly with c-Fos/c-Jun complex and ERG via several distinct ETS2: domains including the C-terminal region that contains the DNA-binding domain, Strikingly, these interactions were stabilized in vitro by DNA as they were inhibited by ethidium bromide, Both the N-terminal region, comprising the transactivation domain, and the C-terminal region of ETS2 associated with ERG and, interestingly, the interaction of ERG through the transactivation domain of ETS2 was DNA-independent, The DNA-dependent interaction of ETS2 with c-Fos/c-Jun was enhanced by specific DNA fragments requiring two Ets-binding-sites of the stromelysin-1 promoter, Using the two hybrid system, we also demonstrated that ETS2 interacts with c-Jun or ERG in vivo.