title: Differential regulation of the TRAIL death receptors DR4 and DR5 by the signal recognition particle.
abstract: TRAIL (TNF-related apoptosis-inducing ligand) death receptors DR4 and DR5 facilitate the selective elimination of malignant cells through the induction of apoptosis. From previous studies the regulation of the DR4 and DR5 cell-death pathways appeared similar; nevertheless in this study we screened a library of small interfering RNA (siRNA) for genes, which when silenced, differentially affect DR4- vs. DR5-mediated apoptosis. These experiments revealed that expression of the signal recognition particle (SRP) complex is essential for apoptosis mediated by DR4, but not DR5. Selective diminution of SRP subunits by RNA interference resulted in a dramatic decrease in cell surface DR4 receptors that correlated with inhibition of DR4-dependent cell death. Conversely, SRP silencing had little influence on cell surface DR5 levels or DR5-mediated apoptosis. Although loss of SRP function in bacteria, yeast and protozoan parasites causes lethality or severe growth defects, we observed no overt phenotypes in the human cancer cells studied--even in stable cell lines with diminished expression of SRP components. The lack of severe phenotype after SRP depletion allowed us to delineate, for the first time, a mechanism for the differential regulation of the TRAIL death receptors DR4 and DR5--implicating the SRP complex as an essential component of the DR4 cell-death pathway.
authors.affiliation: Department of Cancer Biology, Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA.
authors.forename: Yan-Guo
authors.initials: YG
authors.lastname: Ren
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Wagner
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Knee
authors.forename: Pedro
authors.initials: P
authors.lastname: Aza-Blanc
authors.forename: Marc
authors.initials: M
authors.lastname: Nasoff
authors.forename: Quinn L
authors.initials: QL
authors.lastname: Deveraux
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D016923:Cell Death; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D003001:Cloning, Molecular; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D015723:Gene Library; D020868:Gene Silencing; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D034741:RNA, Small Interfering / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D018271:Signal Recognition Particle / Q000378:metabolism; D013347:Subcellular Fractions; D013997:Time Factors; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; C480632:SRP54 protein, human; C503636:SRP72 protein, human; D018271:Signal Recognition Particle; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; D049452:Green Fluorescent Proteins; D008156:Luciferases