title: Use of alpha-, beta-Estrogen Receptor as a "new tool" for detection of specific small molecule activity.
abstract: Cell-based screening methods for nuclear receptor ligands that use transgenic plant cells expressing a single human NR may have advantages over other eukaryotic systems which express multiple NRs. For example, signal-to-noise ratio might be improved because ligands would be less likely to bind to other NRs and/or less likely to cause confounding functional changes in plant cells. As a first step toward this aim we have expressed in plants truncated human estrogen receptor (ER) constructs linked to reporters, or selective markers such as luciferase, green fluorescent protein (GFP) and hygromycin. A variety of ligands for the ER (including estradiol and known phytoestrogens) have then been tested for their ability to over-express the linked marker gene(s) which could be measured (luciferase activity), visualized under fluorescent microscopy (GFP activity), or selected on antibiotic-containing media (Hygromycin B). Our results show a close association between the effects of ER ligands in the transgenic plant roots and their effects on native ERs in mammalian cells. With the stable expression of an ERalpha-GFP ligand detection system inA. thaliana,the estradiol- mediated response in transgenic roots is inhibited by an ER partial agonist (tamoxifen) and an antagonist (fulvestrant) at concentrations relevant to their use in breast cancer. We conclude that it is possible to express human NRs in plants in a form that can report on exogenous or endogenous ER ligands and that these constructs have a pharmacology which is relevant to ligands for the native NRs in human cells.
authors.affiliation: Kentucky Tobacco Research & Development Center, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA.
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Gunjan
authors.affiliation: Naprogenix, Inc. Astecc Labs, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA.
authors.forename: Dennis Trent
authors.initials: DT
authors.lastname: Rogers
authors.affiliation: Kentucky Tobacco Research & Development Center, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA.
authors.forename: Jingxian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Kentucky Tobacco Research & Development Center, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA.
authors.forename: Kil-Young
authors.initials: KY
authors.lastname: Yun
authors.affiliation: Pure Genius Foods, 725 Main St,. Millis, MA 02054, USA.
authors.forename: Deane L
authors.initials: DL
authors.lastname: Falcone
authors.affiliation: Kentucky Tobacco Research & Development Center, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA; Naprogenix, Inc. Astecc Labs, University of Kentucky, 1401 University Drive, Lexington, KY 40546, USA.
authors.forename: John
authors.initials: J
authors.lastname: Littleton
keywords: Estrogen receptor; genetic switch; hairy root; ligand; transgenic