title: Differential binding of mutant glucocorticoid receptors to the glucocorticoid response element of the tyrosine aminotransferase gene.
abstract: Glucocorticoid receptors (GCRs) in sublines of the mouse P1798 lymphosarcoma that are sensitive (S) or resistant (R) to glucocorticoid-induced cell lysis were examined for their ability to bind to a single glucocorticoid responsive element (GRE). Mobility shift assays detected two specific complexes that were identical in both S and R cellular extracts. Antibodies against the GCR N-terminus supershifted complexes, suggesting that the 97 kDa wild-type GCR (WT-GCR) in S cells, and the variant, 97 kDa non-steroid-binding GCR (NSB-GCR) in R cells were components of both complexes. Sephacryl S300 gel filtration column fractions containing the WT-GCR and NSB-GCR formed complexes with the GRE, while fractions containing a second GCR variant in R cells, the 45 kDa steroid-binding truncated GCR (TR-GCR), did not. Southwestern blotting detected a GRE-binding, 97 kDa protein band in both S and R extracts. A 45 kDa band was not detected. UV crosslinking of protein to DNA revealed protein in the range of 92-120 kDa crosslinked to the GRE in both S and R extracts. No crosslinking was detected at 45 kDa. Strong interaction of the NSB-GCR with GREs and lack of binding of the TR-GCR to single GREs illustrate a complex receptor system in the P1798 lymphosarcoma.
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: D000180:Acrylic Resins; D000818:Animals; D001665:Binding Sites; D015139:Blotting, Southern; D015153:Blotting, Western; D004586:Electrophoresis / Q000379:methods; D005938:Glucocorticoids / Q000494:pharmacology; D008228:Lymphoma, Non-Hodgkin / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051379:Mice; D011965:Receptors, Glucocorticoid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014444:Tyrosine Transaminase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D000180:Acrylic Resins; D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D014444:Tyrosine Transaminase