title: Identification and localization of steroid-binding and nonsteroid-binding forms of the glucocorticoid receptor in the mouse P1798 lymphosarcoma.
abstract: Glucocorticoid receptors (GCRs) were characterized in sublines of the mouse P1798 lymphosarcoma that are sensitive (S) or resistant (R) to glucocorticoid-mediated apoptosis. Previous work had identified two steroid-binding GCRs in S and R cells: a 97 kDa wild-type GCR in S cells (WT-GCR), and a 45 kDa truncated GCR in R cells (TR-GCR). A third GCR, a 97 kDa nonsteroid-binding GCR (NSB-GCR), was also identified in R cells. Using subcellular fractionation and Western blotting, we now show that in contrast to the WT-GCR which is localized in both the cytoplasm and nucleus of S cells, the NSB-GCR is localized predominantly in R cell nuclei. Moreover, gel filtration chromatography revealed that treatment with 400 mM NaCl and heat did not significantly alter the Stokes radius of the NSB-GCR suggesting that this receptor is not present in a heterooligomeric complex with other proteins. The TR-GCR was localized predominantly in the soluble cytoplasmic fraction but also in the crude membrane fractions of R cell nuclei, suggesting that this receptor is tightly associated with nuclear structures. It was not detected in the soluble nuclear fraction. Unexpectedly, a 45 kDa nonsteroid-binding immunoreactive protein was detected in crude membrane fractions of S cells. These studies describe a complex GCR system in the P1798 lymphosarcoma that necessitates a further consideration of glucocorticoid signaling in S and R cells.
authors.affiliation: Department of Experimental Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: B G
authors.initials: BG
authors.lastname: Rowan
authors.forename: M M
authors.initials: MM
authors.lastname: Ip
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002458:Cell Fractionation; D002462:Cell Membrane / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry; D002850:Chromatography, Gel; D003593:Cytoplasm / Q000737:chemistry; D004351:Drug Resistance; D005938:Glucocorticoids / Q000378:metabolism / Q000494:pharmacology; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism* / Q000648:ultrastructure; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D011965:Receptors, Glucocorticoid / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013256:Steroids / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D005938:Glucocorticoids; D046911:Macromolecular Substances; D011965:Receptors, Glucocorticoid; D013256:Steroids; D012965:Sodium Chloride