title: Ezrin Binds to DEAD-Box RNA Helicase DDX3 and Regulates Its Function and Protein Level.
abstract: Ezrin is a key regulator of cancer metastasis that links the extracellular matrix to the actin cytoskeleton and regulates cell morphology and motility. We discovered a small-molecule inhibitor, NSC305787, that directly binds to ezrin and inhibits its function. In this study, we used a nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS-MS)-based proteomic approach to identify ezrin-interacting proteins that are competed away by NSC305787. A large number of the proteins that interact with ezrin were implicated in protein translation and stress granule dynamics. We validated direct interaction between ezrin and the RNA helicase DDX3, and NSC305787 blocked this interaction. Downregulation or long-term pharmacological inhibition of ezrin led to reduced DDX3 protein levels without changes in DDX3 mRNA. Ectopic overexpression of ezrin in low-ezrin-expressing osteosarcoma cells caused a notable increase in DDX3 protein levels. Ezrin inhibited the RNA helicase activity of DDX3 but increased its ATPase activity. Our data suggest that ezrin controls the translation of mRNAs preferentially with a structured 5' untranslated region, at least in part, by sustaining the protein level of DDX3 and/or regulating its function. Therefore, our findings suggest a novel function for ezrin in regulation of gene translation that is distinct from its canonical role as a cytoskeletal scaffold at the cell membrane.
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Haydar
authors.initials: H
authors.lastname: Çelik
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Kamal P
authors.initials: KP
authors.lastname: Sajwan
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Saravana P
authors.initials: SP
authors.lastname: Selvanathan
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Marsh
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Amrita V
authors.initials: AV
authors.lastname: Pai
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Yasemin Saygideger
authors.initials: YS
authors.lastname: Kont
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Tsion Z
authors.initials: TZ
authors.lastname: Minas
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Said
authors.initials: S
authors.lastname: Rahim
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Hayriye Verda
authors.initials: HV
authors.lastname: Erkizan
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Toretsky
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA au26@georgetown.edu.
authors.forename: Aykut
authors.initials: A
authors.lastname: Üren
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis / Q000235:genetics*; D040901:Proteomics; D011804:Quinolines / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering; D020349:Surface Plasmon Resonance; D053719:Tandem Mass Spectrometry; D000099149:Ezrin
chemical_list: D000218:Adamantane; D003598:Cytoskeletal Proteins; D053487:DEAD-box RNA Helicases; D011804:Quinolines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000099149:Ezrin; C570896:NSC305787; C119332:DDX3X protein, human