title: Vault Nanoparticles: Chemical Modifications for Imaging and Enhanced Delivery.
abstract: Vault nanoparticles represent promising vehicles for drug and probe delivery. Innately found within human cells, vaults are stable, biocompatible nanocapsules possessing an internal volume that can encapsulate hundreds to thousands of molecules. They can also be targeted. Unlike most nanoparticles, vaults are nonimmunogenic and monodispersed and can be rapidly produced in insect cells. Efforts to create vaults with modified properties have been, to date, almost entirely limited to recombinant bioengineering approaches. Here we report a systematic chemical study of covalent vault modifications, directed at tuning vault properties for research and clinical applications, such as imaging, targeted delivery, and enhanced cellular uptake. As supra-macromolecular structures, vaults contain thousands of derivatizable amino acid side chains. This study is focused on establishing the comparative selectivity and efficiency of chemically modifying vault lysine and cysteine residues, using Michael additions, nucleophilic substitutions, and disulfide exchange reactions. We also report a strategy that converts the more abundant vault lysine residues to readily functionalizable thiol terminated side chains through treatment with 2-iminothiolane (Traut's reagent). These studies provide a method to doubly modify vaults with cell penetrating peptides and imaging agents, allowing for in vitro studies on their enhanced uptake into cells.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Benner
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zang
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Buehler
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine at University of California Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Kickhoefer
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine at University of California Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Rome
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine at University of California Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Rome
authors.forename: Paul A
authors.identifier: 0000-0001-6319-2829
authors.initials: PA
authors.lastname: Wender
mesh_terms: D000818:Animals; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D061848:Optical Imaging; D000067996:RAW 264.7 Cells; D013329:Structure-Activity Relationship; D020394:Vault Ribonucleoprotein Particles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D005456:Fluorescent Dyes; D020394:Vault Ribonucleoprotein Particles
keywords: cell-penetrating transporter; chemical modification; imaging; nanoparticle; protein cage; vaults