Our general interests are in the regulation of eukaryotic gene expression, primarily at the transcriptional level. This includes studies on transcription factor binding to promoter elements in the genes within DNA, within nucleosomes and how this relates to in vitro transcription utilizing reporter genes. In addition, in many of these studies the impact of the coactivator protein, HMGB1, on the thermodynamic and kinetic binding processes is investigated, in addition to its role in the expression of the gene (transcriptional activity).
We have studied many of the proteins involved in the assembly of the preinitiation complex (PIC) on TATA-containing promoters. These include the TATA-binding protein (TBP), TFIIB, TFIIA and HMGB1. We are currently focusing a great deal of our efforts on the understanding how hormone-responsive genes are regulated by their ligand-activated nuclear hormone receptors. In this regard, we have shown that although the estrogen receptors (ER), alpha & beta, do bind to their "classical" palindromic recognition sequences (ERE, estrogen response elements) that contain a 3 bp spacer, their high binding affinity extends far beyond this, including an individual half-site of the ERE,(referred to as HERE). The importance of HEREs is becoming more apparent as more extensive data from the human genome are harvested, including findings from ChIP (chromatin immunoprecipitation) and Chip-CHIP (chromatin immunoprecipitation coupled with DNA microchip) assays. These findings suggest that HEREs may play an important role in the regulation of estrogen-responsive genes and that the binding of ER to DNA is much more promiscuous than currently accepted models present.
Joshi, S. R., Sarpong, Y. C., Peterson, R. C. & Scovell, W. M.. (2012) Nucleosome Dynamics: HMGB1 Relaxes Canonical Nucleosome Structure to Facilitate Estrogen Receptor Binding. Nucleic Acids Res. 40,10161-10171.
Joshi, S. R., Ghattamaneni, R. B. & Scovell, W. M. (2011) Expending the Paradigm for Estrogen Receptor Binding and Transcriptional Activation. Mol. Endocrinol. 25, 980-994.
El Marzouk, S., Gahattamaneni, R., Joshi, S. R. & Scovell, W. M. (2008) The Plasticity of Estrogen Receptor-DNA Complexes: Binding Affinity and Specificity of Estrogen Receptors to Estrogen Response Element Half-sites Separated by Variant Spacers. J. Steroid Biochem. Mol. Biol. 110, 186-195.
Das, D., Peterson, R. C. & Scovell, W. M., HMGB1 High Mobility Group B1 Proteins Facilitate Strong Estrogen Receptor Binding to Classical and Half-site Estrogen Response Elements and Relax Binding Selectivity, Mol. Endocrinol., 18, 2616-2632 (2004).
Dasgupta & W. M. Scovell, Competition Between HMGB1 and EIA with TFIIA in the Early Stages of Assembly of the Transcriptional Preinitiation Complex, Biochim. Biophys. Acta, 1627, 101-110 (2003).
D. Das & W. M. Scovell, The Binding Interaction of HMG-1 with the TATA-Binding Protein/TATA Complex, J. Biol. Chem. 276, 32597-35605 (2001). Selected as "Hot Paper" in Chromatin Structure and Function.
W. Lu, R. Peterson, A. Dasgupta & W. M. Scovell, Influence of HMG-1 and Adenovirus Oncoprotein E1A on Early Stages of Transcriptional Preinitiation Complex Assembly, J. Biol. Chem. 275, 35006-35012 (2000).
W. Ranatunga, J. Lebowitz, B. Axe, P. Pavlik, S. R. Kar & W. M. Scovell, Reexamination of the High Mobility Group-1 Protein For Self-Association and Characterization of Hydrodynamic Properties, Biochim. Biophys. Acta 1432, 1-12 (1999).