title: Characterization of the fundamental properties of the N-terminal truncation (Δ exon 1) variant of estrogen receptor α in the rat.
abstract: The estrogen receptor α (ERα) directs transactivation of target genes, and splice variants have been shown to exhibit altered activation properties. We previously documented the complicated alternative promoter usage and splicing patterns of the rat ERα gene; however, the information was restricted to a few specific organs. Therefore, we re-examined the rat mRNA profiles of ERα, including the generation of the exon 1-skipping, ERα46 transcript in a wider variety of rat organs and further characterized the fundamental functional properties of rat ERα46 variants. With the use of RT-PCR, we discovered unique distribution and splicing patterns for promoter-specific ERα isoforms, as well as the extensive expression of the Δ exon 1 variant in the rat. Similar to wild-type ERα, an immunocytochemical analysis showed a predominant localization of ERα46 proteins in the nuclei of transfected cells. Luciferase reporter assays revealed that ERα46 variants stimulated the transcriptional activity of an estrogen response element-driven promoter in response to estrogen. In addition, the variants exhibited distinct transactivation and reactivity to 4-hydroxytamoxifen in different cell types. Although the alternative splicing patterns are species-specific, the profiles of the alternative use of promoters, and the fundamental properties of the rat ERα46 variant are similar to those of human and mouse homologs. Therefore, the present study provides fundamental and useful information for further research into the regulation and functions of ERα gene variants.
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan; Department of Neurosurgery, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Hattori
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. Electronic address: hirotaka@nms.ac.jp.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ishii
authors.affiliation: Department of Neurosurgery, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
authors.affiliation: University of Tokyo Health Sciences, 4-11 Ochiai, Tama, Tokyo 206-0033, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sakuma
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ozawa
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000235:genetics* / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology; D005091:Exons / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects; D014644:Genetic Variation; D057809:HEK293 Cells; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017208:Rats, Wistar; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D047628:Estrogen Receptor alpha; D004967:Estrogens; D020033:Protein Isoforms; D013629:Tamoxifen; C016601:afimoxifene
keywords: Alternative promoter usage; Alternative splicing; ERα46; ERα66; Estrogen receptor α; Splice variant