DNA octamer element can confer E1A trans-activation, and adenovirus infection results in a stimulation of the DNA-binding activity of OTF-1/NFIII factor

Abstract

Adenovirus E1A-dependent trans-activation of viral transcription involves the utilization and alteration of multiple sequence-specific transcription factors. Cellular genes are also activated by E1A, one example being the immunoglobulin heavy-chain locus when assayed by transfection into fibroblast cells. We have explored the basis for the E1A-dependent activation of this cellular transcription unit. We demonstrate that the ATTTGCAT ("octamer") element found in the heavy-chain enhancer and promoter is a target for E1A trans-activation since this sequence can confer inducibility to the normally unresponsive simian virus 40 early promoter. In addition, adenovirus infection stimulates the DNA-binding activity of the ubiquitous octamer-specific factor, OTF-1, and we presume that this is the basis for the stimulation of transcription. Although there are no octamer elements in the adenovirus genome that are known to be important for transcription, there are octamer elements in the viral terminal repeat sequences. These elements bind the NFIII factor and are important for the initiation of DNA replication. Since the NFIII factor has been shown to be identical to OTF-1, we suggest that the stimulation of OTF-1/NFIII activity during an adenovirus infection may be important for efficient initiation of adenovirus DNA synthesis.