We have analyzed Emx2 enhancers to determine how Emx2 functions during forebrain development are regulated. The FB (forebrain) enhancer we identified immediately 3' downstream of the last coding exon is well conserved among tetrapods and unexpectedly directed all the Emx2 expression in forebrain: caudal forebrain primordium at E8.5, dorsal telencephalon at E9.5-E10.5 and the cortical ventricula...

Transcription of the herpes simplex virus 1 (HSV-1) immediate early (IE) genes is determined by multiprotein enhancer complexes. The core enhancer assembly requires the interactions of the POU-homeodomain protein Oct-1, the viral transactivator alphaTIF and the cellular factor C1 (HCF). In this context, the C1 factor interacts with each protein to assemble the stable enhancer complex. In additi...

Enhancer elements regulate the tissue- and developmental-stage-specific expression of genes. Recent estimates suggest that there are more than 50,000 enhancers in mammalian cells. At least a subset of enhancers has been shown to recruit RNA polymerase II transcription complexes and to generate enhancer transcripts. Here, we provide an overview of enhancer function and discuss how transcription ...

In the yeast Saccharomyces cerevisiae, each of the tandemly repeated ribosomal RNA genes carries a 5S gene within the 'non-transcribed' spacer region. These 5S RNA genes lie between the rDNA enhancer and the promoter of rRNA transcription. Since there is roughly equimolar synthesis of 5S RNA and the 35S rRNA precursor transcript we asked whether the enhancer plays a role in regulating the trans...

Hunchback (Hb) is a bifunctional transcription factor that activates and represses distinct enhancers. Here, we investigate the hypothesis that Hb can activate and repress the same enhancer. Computational models predicted that Hb bifunctionally regulates the even-skipped (eve) stripe 3+7 enhancer (eve3+7) in Drosophila blastoderm embryos. We measured and modeled eve expression at cellular resol...

We recently identified enhancer elements that activate the weak 3' splice site of alpha-tropomyosin exon 2 as well as a variety of heterologous weak 3' splice sites. To understand their mechanism of action, we devised an iterative selection strategy to identify functional pyrimidine tracts and branchpoint sequences in the presence or absence of enhancer elements. Surprisingly, we found that str...

The protein sigma 54 associates with Escherichia coli core RNA polymerase to form a holoenzyme that binds promoters but is inactive in the absence of enhancer activation. Here, mutants of sigma 54 enabled polymerases to transcribe without enhancer protein and adenosine triphosphate. The mutations are in leucines within the NH2-terminal glutamine-rich domain of sigma 54. Multiple leucine substit...

Lineage-specific transcription factors are critical for long-range enhancer interactions, but direct or indirect contributions of architectural proteins such as CCCTC-binding factor (CTCF) to enhancer function remain less clear. The LDB1 complex mediates enhancer-gene interactions at the β-globin locus through LDB1 self-interaction. We find that an LDB1-bound enhancer upstream of carbonic anhyd...

Lymphomagenesis in the presence of deregulated MYC requires suppression of MYC-driven apoptosis, often through downregulation of the pro-apoptotic BCL2L11 gene (Bim). Transcription factors (EBNAs) encoded by the lymphoma-associated Epstein-Barr virus (EBV) activate MYC and silence BCL2L11. We show that the EBNA2 transactivator activates multiple MYC enhancers and reconfigures the MYC locus to i...

The rat carbamyl phosphate synthetase I gene is expressed in two cell types: hepatocytes and epithelial cells of the intestinal mucosa. The proximal promoter contains a single activating element, GAG, two repressor elements (sites I and III) and an anti-repressor element (site II). Although these elements together exhibit the potential for complex regulation, they are unable to confer tissue-sp...