Abstract
This course of research examines ligand interactions with nuclear receptors and cross-talk between receptors and implications for human health by using a number of different scientific research tools. These include in silico molecular modelling using nuclear receptor crystal structures; in vitro assays and multivariate analytical techniques to derive robust models of receptor activation. The selection of ligands were based both on literature reviews, which constitutes Chapter 1, (Jacobs and Lewis, 2002) and Chapter 2, an environmental pollutant case study of contaminants in the aquaculture food chain and dietary oil studies (Jacobs et al., 2002a; 2002b). The data from these studies informed likely relative dietary exposure of individual environmental contaminant congeners of European consumers of oily fish and oils (Jacobs et al., 2002a; 2002b; Jacobs et al., 2002c; Jacobs, 2002; Jacobs, 2003). While they were conducted in addition to the molecular work, as they contained information pertinent to my PhD project, and the studies were conducted at similar times, they have been included here as a legitimate and informative avenue of study. However they were not funded by my PhD funding through the BBSRC and GSK, University of Surrey facilities were not used, and they were conducted independently, in my own time, outside the time allocated for my PhD work. For support and collaboration with these studies I am extremely grateful to Joe Ferrario of the US Environmental Protection Agency, and Adrian Covaci, of the University of Antwerp, Belgium. Chapter 3 presents the receptor models built and the relevant crystal structures used for the ERB, AhR, PXR, CAR, and PPAR models (Jacobs et al., 2003a). These models or the crystal structure if available later, are shown with ligands of interest docked in the ligand binding domains of the relevant receptors. Differences in the ligand binding domains and modes of binding were observed. These studies provided an additional basis for selection of experimental compounds to test in an in vitro nuclear receptor assay described in Chapter 4, and supported the receptor based Quantitative Structure Activity Relationships (QSARs) described in Chapter 5. Chapter 4 describes how the biological data was generated experimentally utilising the in house GSK PXR transient transfection assay at the GSK site in Ware, UK. Additional biologically relevant data for PXR and ERa and AhR was obtained from GSK in house data sets, the literature and unpublished data was also kindly provided by Guosheng Chen from the University of Guelph, Canada (Jacobs et al. 2003b). These data sets were utilised to generate the QSARs presented in Chapter 5. The QSARs presented were supported by further exploration of the modes of ligand binding in the crystal structures and/or homology models of the SHRs under study. Chapter 6 discusses the applications of the studies documented in the preceding chapters and future avenues of related research with particular reference to the implications of the studies presented here for human health. Endocrine systems need to be allowed to maintain their equilibrium. Perturbing the endocrine system can result in ill health, reduced quality of life, and loss of self.