title: Arf and Rho GAP adapter protein ARAP1 participates in the mobilization of TRAIL-R1/DR4 to the plasma membrane.
abstract: TRAIL, a ligand of the TNFalpha family, induces upon binding to its pro-death receptors TRAIL-R1/DR4 and TRAIL-R2/DR5 the apoptosis of cancer cells. Activated receptors incite the formation of the Death-Inducing Signaling Complex followed by the activation of the downstream apoptotic signaling. TRAIL-induced apoptosis is regulated at multiple levels, one of them being the presence and relative number of TRAIL pro- and anti-apoptotic receptors on the cytoplasmic membrane. In a yeast two-hybrid search for proteins that interact with the intracellular part (ICP) of DR4, we picked ARAP1, an adapter protein with ArfGAP and RhoGAP activities. In yeast, DR4(ICP) interacts with the alternatively spliced ARAP1 lacking 11 amino acids from the PH5 domain. Transfected ARAP1 co-precipitates with DR4 and co-localizes with it in the endoplasmic reticulum/Golgi, at the cytoplasmic membrane and in early endosomes of TRAIL-treated cells. ARAP1 knockdown significantly compromises the localization of DR4 at the cell surface of several tumor cell lines and slows down their TRAIL-induced death. ARAP1 overexpressed in HEL cells does not affect their TRAIL-induced apoptosis or the membrane localization of DR4, but it enhances the cell-surface presentation of phosphatidyl serine. Our data indicate that ARAP1 is likely involved in the regulation of the cell-specific trafficking of DR4 and might thus affect the efficacy of TRAIL-induced apoptosis.
authors.affiliation: Laboratory of Cell Signaling and Apoptosis, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídenská 1083, 14220, Praha 4, Czech Republic.
authors.forename: Sárka
authors.initials: S
authors.lastname: Símová
authors.forename: Martin
authors.initials: M
authors.lastname: Klíma
authors.forename: Lukas
authors.initials: L
authors.lastname: Cermak
authors.forename: Vladimíra
authors.initials: V
authors.lastname: Sourková
authors.forename: Ladislav
authors.initials: L
authors.lastname: Andera
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D015536:Down-Regulation; D020690:GTPase-Activating Proteins / Q000502:physiology*; D006801:Humans; D025941:Protein Interaction Mapping; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C446513:ARAP1 protein, human; D002352:Carrier Proteins; D020690:GTPase-Activating Proteins; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505653:TNFSF10 protein, human