@article{tompkins_sit_wallace_2008, title={Unique transcription start sites and distinct promoter regions differentiate the pregnane X receptor (PXR) isoforms PXR 1 and PXR 2}, volume={36}, ISSN={["1521-009X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42449091555&partnerID=MN8TOARS}, DOI={10.1124/dmd.107.018317}, abstractNote={The pregnane X receptor (PXR) is known as the xenosensing receptor responsible for coordinated regulation of metabolic genes in response to diverse xenobiotic challenges. In particular, the ability of the PXR to regulate CYP3A4, the enzyme capable of metabolizing more than 60% of all pharmaceuticals, defines its metabolic importance. Currently the list of PXR ligands and target genes is extensive, yet investigations into the regulation and expression of PXRs are few. After an initial review of available sequence data, we discovered discrepancies in the 5′ untranslated region (UTR) and transcriptional start site (TSS) characterizations of the human PXR gene and subsequently endeavored to define TSSs and proximal promoters for isoforms PXR 1 and PXR 2. Reverse transcriptase-polymerase chain reaction and primer extension experiments performed on RNA from human liver identified two TSSs for each receptor isoform. These results extended the 5′UTR sequence of each isoform and defined new proximal promoters for both. Candidate response elements for liver-enriched transcription factors and other receptors were found in both proximal promoters. Quantitative PCR from human liver illustrated a highly variable expression profile for total PXRs; yet PXR 2 expression represented a consistent 2 to 5% of total PXR expression, despite the observed variability. Transfection experiments demonstrated that PXR 1 and PXR 2 had comparable abilities to transcriptionally activate the CYP3A4 promoter. Collectively, comparable function, consistent expression, and independent regulation suggest that PXR 2 is capable of contributing to the cumulative function of PXRs and should be included in the larger investigations of PXR expression and regulation.}, number={5}, journal={DRUG METABOLISM AND DISPOSITION}, publisher={American Society for Pharmacology & Experimental Therapeutics (ASPET)}, author={Tompkins, Leslie M. and Sit, Tim L. and Wallace, Andrew D.}, year={2008}, month={May}, pages={923–929} }
 @article{tompkins_wallace_2007, title={Mechanisms of cytochrome P450 induction}, volume={21}, number={4}, journal={Journal of Biochemical and Molecular Toxicology}, author={Tompkins, L. M. and Wallace, A. D.}, year={2007}, pages={176–181} }
 @article{li_newman_cesta_tompkins_khosla_sannes_2003, title={Modulation of fibroblast growth factor expression and signal transduction in type II cells}, volume={123}, ISSN={["0012-3692"]}, DOI={10.1378/chest.123.3_suppl.429S}, abstractNote={repair and wound healing. PDGFs are synthesized and secreted by most inflammatory cell types present within the milieu of the asthmatic airway. We have previously reported that airway fibroblasts from severe asthmatics produce more type I procollagen in response to PDGF stimulation as compared to patients with mild asthma and normal control subjects; therefore, we hypothesized that the enhanced responsiveness to PDGFs in patients with severe asthma is linked to an increased expression of PDGF receptors. In an ongoing study, 5 subjects with severe asthma, 10 subjects with mild-to-moderate asthma, and 6 normal control subjects underwent bronchoscopy with endobronchial biopsy. Biopsies were placed in Dulbecco’s modified Eagle’s serum supplemented with fetal bovine serum (10%), streptomycin (100 g/mL), penicillin (10,000 U/mL), and gentamicin (100 g/mL), and cultured until fibroblast growth was established at 50% confluency (approximately 8 to 20 days). Immunostaining with vimentin (Dako; Carpenteria, CA), Ab-1 (Calbiochem; San Diego, CA) and -smooth muscle actin (Dako) confirmed fibroblast identity. To determine baseline fibroblast expression of PDGF receptors (PDGFRs) [PDGFRand PDGFR], we developed a sandwich enzyme-linked immunosorbent assay for these receptors that quantifies receptor protein levels in fibroblast cell lysates. Receptor protein levels were expressed in nanograms per 100 g of total cell protein. There were no significant differences in baseline expression of PDGFRbetween the groups (severe, 7.6 ng/100 g protein; mild to moderate, 12.50 ng/100 g protein; normal control, 11.33 ng/100 g protein; p 0.35). However, there was a significantly greater baseline expression of PDGFRin the severe asthmatic group, as compared to both the mild/moderate asthmatic and normal control groups (severe, 15.20 ng/100 g protein; mild-to-moderate, 13.30 ng/100 g protein; normal control, 3.67 ng/100 g protein; p 0.0024). Our data suggests that airway fibroblasts from severe asthmatics may be of a synthetic phenotype, with altered capabilities in collagen production, as compared to those from patients with mild-to-moderate asthma and normal control subjects, and this may be driven by an increased expression of PDGFR. Modulation of Fibroblast Growth Factor Expression and Signal Transduction in Type II Cells*}, number={3}, journal={CHEST}, author={Li, CM and Newman, D and Cesta, M and Tompkins, L and Khosla, J and Sannes, PL}, year={2003}, month={Mar}, pages={429S–429S} }