Interaction between E-protein and Oct transcription factors in the function of the catfish IGH enhancer

Transcriptional control of the immunoglobulin heavy chain (IGH) locus in the channel catfish, Ictalurus punctatus, is incompletely understood. It is, however, known that 2 variant octamer motifs and a μE5 motif in the core region of the enhancer (Eμ3′) are important in driving transcription, and it has been suggested that interaction between transcription factors (Oct factors and E-proteins) bound to these sites contributes to enhancer function. In this study, the functional relationships between the μE5 motif, the proximal octamer motif, and the factors that bind them have been examined. The results of mutational analysis of these motifs showed that their interaction is important to driving transcription from the enhancer. Furthermore, the catfish Oct transcription factors were capable of a physical interaction with the catfish E-proteins. These results support a role for interaction between transcription factors bound to the octamer and μE5 motifs in the function of the Eμ3′ enhancer.