Multiple negative elements upstream of the murine c-myc gene share nuclear factor binding sites with SV40 and polyoma enhancers

We previously identified a 716 bp DNA segment, 424 to 1140 bp 5' of the murine c-myc gene, which exhibited the properties of a transcriptional 'dehancer' because it negated the effects of the SV40 enhancer (Remmers et al., 1986). Here, we show that this 716 bp 'dehancer region' is composed of multiple negative elements each of which functions at a distance of > 1 Kb to inhibit the SV40 enhancer. One of these negative elements displays lymphoid cell specificity. HeLa cell nuclear factor binding sites are found within these negative effector sequences. One of these binding sites is related to that of the Py EF-C transcription factor which recognizes a short dyad symmetry element within the polyoma enhancer. Interestingly, a dimer of the Py EF-C recognition sequence exhibited a strong 'dehancer effect' in the pSV2CAT expression vector. These negative elements may function by interfering with transcription factors required for SV40 enhancer activity.