title: Metabolic biotinylation of cell surface receptors for in vivo imaging.
abstract: We have developed a versatile, potent technique for imaging cells in culture and in vivo by expressing a metabolically biotinylated cell-surface receptor and visualizing it with labeled streptavidin moieties. The recombinant reporter protein, which incorporates a biotin acceptor peptide (BAP) between an N-terminal signal sequence and a transmembrane domain, (BAP-TM) was efficiently biotinylated by endogenous biotin ligase in mammalian cells with the biotin displayed on the cell surface. Tumors expressing the BAP-TM have high sensitivity for magnetic resonance and fluorescence tomographic imaging in vivo after intravascular injection of streptavidin conjugated to magnetic nanoparticles or fluorochromes, respectively. Moreover, streptavidin-horseradish peroxidase conjugates in conjunction with a peroxidase-sensitive gadolinium agent further increased and prolonged the magnetic resonance signal. This BAP-TM allows noninvasive real-time imaging of any cell type transduced to express this reporter protein in culture or in vivo.
authors.affiliation: Center for Molecular Imaging Research, Massachusetts General Hospital-East, Building 149, 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Bakhos A
authors.initials: BA
authors.lastname: Tannous
authors.forename: Jan
authors.initials: J
authors.lastname: Grimm
authors.forename: Katherine F
authors.initials: KF
authors.lastname: Perry
authors.forename: John W
authors.initials: JW
authors.lastname: Chen
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Xandra O
authors.initials: XO
authors.lastname: Breakefield
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000378:metabolism*; D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D010455:Peptides / Q000737:chemistry; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D019809:Streptavidin / Q000737:chemistry; D014161:Transduction, Genetic
chemical_list: D010455:Peptides; D011956:Receptors, Cell Surface; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D001710:Biotin; D019809:Streptavidin