title: Correlation of membrane glucocorticoid receptor levels with glucocorticoid-induced apoptotic competence using mutant leukemic and lymphoma cells lines.
abstract: We have studied the presence and functional implications of membrane glucocorticoid receptor (mGR) in several wild type (WT) and mutant mouse lymphoid cell lines (nuclear transfer decrease, NT(-); nuclear transfer increase, NT(i); and receptorless, R(-)). Direct fluorescent antibody staining revealed large aggregates of mGR-specific fluorescing antigens in the plasma membrane of the WT and mGR-enriched (mGR(++)) S-49 cells. While R(-) cells totally lacked mGR, this receptor level was low in NT(-) and NT(i) groups. FACS analysis corroborated these results, showing a approximately 4-10-fold difference between the highest mGR levels (mGR(++)) and the R(-) and NT(i) cells. Membrane extracts were analyzed for mGR by immunoblotting. Multiple receptor forms, ranging in M(r) from 94,000 to > 200,000, were observed in the WT cells, while only smaller peptides (85,000-94,000) were found in NT(-) cells. No detectable immunoreactive bands were identified in either membrane or cytosol immunoprecipitates of NT(i) and R(-) cell groups. Within 48 h post dexamethasone exposure > 98% of WT and mGR(++) S-49 cells underwent apoptosis, compared to 0-30% in the mutant cells, albeit the total receptor number is two to three times higher in NT(i) compared to WT. These results suggest a better correlation between the quantity and quality of mGRs (rather than total cellular GRs) and the ability of glucocorticoids (GCs) to lyse lymphoid cells.
authors.affiliation: Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. gametchu@mcw.edu
authors.forename: Bahiru
authors.initials: B
authors.lastname: Gametchu
authors.forename: Cheryl S
authors.initials: CS
authors.lastname: Watson
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001665:Binding Sites; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient / Q000379:methods; D003907:Dexamethasone / Q000494:pharmacology; D005434:Flow Cytometry; D019085:Fluorescent Antibody Technique, Direct; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D008223:Lymphoma / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D011485:Protein Binding; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013223:Statistics as Topic; D014407:Tumor Cells, Cultured
chemical_list: D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone