title: PtdIns(4,5)P-restricted plasma membrane localization of FAN is involved in TNF-induced actin reorganization.
abstract: The WD-repeat protein factor associated with nSMase activity (FAN) is a member of the family of TNF receptor adaptor proteins that are coupled to specific signaling cascades. However, the precise functional involvement of FAN in specific cellular TNF responses remain unclear. Here, we report the involvement of FAN in TNF-induced actin reorganization and filopodia formation mediated by activation of Cdc42. The pleckstrin-homology (PH) domain of FAN specifically binds to phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P), which targets FAN to the plasma membrane. Site-specific mutagenesis revealed that the ability of FAN to mediate filopodia formation was blunted either by the destruction of the PtdIns(4,5)P binding motif, or by the disruption of intramolecular interactions between the PH domain and the adjacent beige and Chediak-Higashi (BEACH) domain. Furthermore, FAN was shown to interact with the actin cytoskeleton in TNF-stimulated cells via direct filamentous actin (F-actin) binding. The results of this study suggest that PH-mediated plasma membrane targeting of FAN is critically involved in TNF-induced Cdc42 activation and cytoskeleton reorganization.
authors.affiliation: Institute for Medical Microbiology, Immunology and Hygiene, Medical Faculty, University of Cologne, Cologne, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Haubert
authors.forename: Nina
authors.initials: N
authors.lastname: Gharib
authors.forename: Francisco
authors.initials: F
authors.lastname: Rivero
authors.forename: Katja
authors.initials: K
authors.lastname: Wiegmann
authors.forename: Marianna
authors.initials: M
authors.lastname: Hösel
authors.forename: Martin
authors.initials: M
authors.lastname: Krönke
authors.forename: Hamid
authors.initials: H
authors.lastname: Kashkar
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D048069:Tumor Necrosis Factors / Q000494:pharmacology*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; C491112:Nsmaf protein, mouse; D019269:Phosphatidylinositol 4,5-Diphosphate; D048069:Tumor Necrosis Factors; D020764:cdc42 GTP-Binding Protein