title: Intracellular localization of RORalpha is isoform and cell line-dependent.
abstract: The retinoid-related orphan receptor alpha (RORalpha) belongs to the nuclear receptor superfamily and comprises four isoforms generated by different promotor usage and alternative splicing. To better understand its function, the subcellular distribution of RORalpha was investigated. We could show that subcellular distribution of RORalpha is cell line and isoform-dependent. Isoform specific differences were mediated by the A/B domains which with the exception of RORalpha1 contain a signal that mediates cytoplasmic localization. The lack of this signal in RORalpha1 results in a complete nuclear localization and prevents cell membrane association observed for RORalpha2, 3, and 4. The region responsible for membrane association was identified as the C-terminal alpha-helix 12. Furthermore, the hinge region/ligand binding domain mediates nuclear localization. Our results show that isoform specific activity of RORalpha is not only regulated by different expression and DNA binding affinities but also by different subcellular distribution. Different access to the nucleus reveals an important mechanism regulating the activity of this constitutively active nuclear receptor.
authors.affiliation: Institute of Pharmaceutical Chemistry/ZAFES, University of Frankfurt, Max-von-Laue Strasse 9, D-60438 Frankfurt am Main, Germany.
authors.forename: Angelique
authors.initials: A
authors.lastname: Aschrafi
authors.forename: Nadine
authors.initials: N
authors.lastname: Meindl
authors.forename: Beate
authors.initials: B
authors.lastname: Firla
authors.forename: Ralf P
authors.initials: RP
authors.lastname: Brandes
authors.forename: Dieter
authors.initials: D
authors.lastname: Steinhilber
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D020033:Protein Isoforms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D015534:Trans-Activators; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D020033:Protein Isoforms; C539738:RORA protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins