title: Targeting cell surface receptors with ligand-conjugated nanocrystals.
abstract: To explore the potential for use of ligand-conjugated nanocrystals to target cell surface receptors, ion channels, and transporters, we explored the ability of serotonin-labeled CdSe nanocrystals (SNACs) to interact with antidepressant-sensitive, human and Drosophila serotonin transporters (hSERT, dSERT) expressed in HeLa and HEK-293 cells. Unlike unconjugated nanocrystals, SNACs were found to dose-dependently inhibit transport of radiolabeled serotonin by hSERT and dSERT, with an estimated half-maximal activity (EC(50)) of 33 (dSERT) and 99 microM (hSERT). When serotonin was conjugated to the nanocrystal through a linker arm (LSNACs), the EC(50) for hSERT was determined to be 115 microM. Electrophysiology measurements indicated that LSNACs did not elicit currents from the serotonin-3 (5HT(3)) receptor but did produce currents when exposed to the transporter, which are similar to those elicited by antagonists. Moreover, fluorescent LSNACs were found to label SERT-transfected cells but did not label either nontransfected cells or transfected cells coincubated with the high-affinity SERT antagonist paroxetine. These findings support further consideration of ligand-conjugated nanocrystals as versatile probes of membrane proteins in living cells.
authors.affiliation: Department of Chemistry, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Rosenthal
authors.forename: Ian
authors.initials: I
authors.lastname: Tomlinson
authors.forename: Erika M
authors.initials: EM
authors.lastname: Adkins
authors.forename: Sally
authors.initials: S
authors.lastname: Schroeter
authors.forename: Scott
authors.initials: S
authors.lastname: Adams
authors.forename: Laura
authors.initials: L
authors.lastname: Swafford
authors.forename: James
authors.initials: J
authors.lastname: McBride
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Louis J
authors.initials: LJ
authors.lastname: DeFelice
authors.forename: Randy D
authors.initials: RD
authors.lastname: Blakely
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D004594:Electrophysiology; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D008024:Ligands; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D026901:Membrane Transport Proteins; D036103:Nanotechnology / Q000379:methods*; D009419:Nerve Tissue Proteins; D009865:Oocytes / Q000378:metabolism / Q000502:physiology; D012701:Serotonin / Q000737:chemistry* / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins; D013379:Substrate Specificity; D014162:Transfection; D014981:Xenopus
chemical_list: D002352:Carrier Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin