title: TRAIL-induced apoptosis in U-1242 MG glioma cells.
abstract: Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) induces apoptosis in U-1242 MG cells. To investigate the molecular events involved in this process, we studied the effects of TRAIL on the localization within membrane fractions of molecules critical to the extrinsic apoptotic pathway. We report here that death receptor-5 (DR5), tumor necrosis factor receptor-1 (TNF-R1), and Fas receptor (FasR) are all located in the caveolin-1-enriched membrane fractions, and TRAIL caused the translocation of DR5, FasR, and TNF-R1 to the caveolar fractions. Caspase-8 is mainly located outside of caveolae, but TRAIL caused it to redistribute to the caveolin-1-enriched fractions where it was cleaved. Within 6 hours, the cleaved caspase-8 appeared in the high-density, noncaveolin fractions. Using confocal microscopy, we found that DR5, caspase-8, and caveolin-1 became progressively concentrated in blebs of plasmalemma as they formed in response to TRAIL. Our results provide the first evidence for the caveolar localization of TNF-R1 and DR5 and the coordinated redistribution among membrane fractions of several death receptors in response to TRAIL. We propose that the coordinated movement of these molecules among membrane compartments is probably an important component of the mechanisms regulating and initiating the extrinsic apoptotic pathway in human glioma cells.
authors.affiliation: Department of Pathology, The Ohio State University, 4166 Graves Hall, 333 W. 10th Avenue, Columbus, OH 43210, USA.
authors.forename: H E
authors.initials: HE
authors.lastname: Saqr
authors.forename: O M
authors.initials: OM
authors.lastname: Omran
authors.forename: J L
authors.initials: JL
authors.lastname: Oblinger
authors.forename: A J
authors.initials: AJ
authors.lastname: Yates
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D021941:Caveolae / Q000737:chemistry / Q000378:metabolism; D002458:Cell Fractionation; D045744:Cell Line, Tumor; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases