ERM, A PEA3 SUBFAMILY OF ETS TRANSCRIPTION FACTORS, CAN COOPERATE WITH C-JUN

A human cDNA clone for ERM, a member of the ets gene family, has been obtained by polymerase chain reaction with degenerate primers correspo nding to highly conserved regions within an Ets DNA binding domain. ER M mRNA is expressed ubiquitously. The gene was mapped to chromosome 3q 27. In in vivo transient-expression assays, ERM induced transcription more efficiently from a synthetic element containing both an ets-bindi ng site (EBS) and a cyclic AMP response element (CRE) than from one co ntaining an EBS alone. The activation of a synthetic EBS-CRE site by E RM was likely to involve a leucine zipper protein capable of dimerizin g with CRE-BP1 leucine zipper. Indeed, ERM and c-Jun synergistically a ctivated the EBS-CRE without making an apparent ternary complex. The s ynergy between c-Jun and ERM may be attributed to the enhancing effect of c-Jun on the transcription activity of ERM, because c Jun increase d ERM transcription activity by more than 20-fold in an assay system u sing a variety of fusion proteins between a Ga14 DNA-binding domain an d a portion of ERM. This enhancing effect of c-Jun required the amino- terminal portion of ERM.