title: Aggregation-mediated macromolecular uptake by a molecular transporter.
abstract: Endocytosis is a key process in cellular delivery of macromolecules by molecular transporters, although the mechanism of internalization remains unclear. Here, we probe the cellular uptake of streptavidin using biotinylated guanidinoneomycin (biotinGNeo), a low molecular weight guanidinium-rich molecular transporter. Two distinct modes were explored: (i) incubation of cells with a preformed tetravalent streptavidin-(biotinGNeo)4 conjugate and (ii) preincubation of cells with the biotinGNeo before exposure to streptavidin. A significant enhancement in uptake was observed after preincubation with biotinGNeo. FRET studies showed that the enhanced uptake was accompanied by extensive aggregation of streptavidin on the cell surface. Because guanidinylated neomycin was previously found to exclusively bind to heparan sulfate, our observations suggest that heparan sulfate proteoglycan aggregation is a pivotal step for endocytic entry into cells by guanidinoglycosides. These observations put forward a practical and general pathway for the cellular delivery of diverse macromolecules.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Makoto
authors.initials: M
authors.lastname: Inoue
authors.forename: Wenyong
authors.initials: W
authors.lastname: Tong
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Esko
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Tor
mesh_terms: D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004705:Endocytosis; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D046911:Macromolecular Substances / Q000378:metabolism*
chemical_list: D019812:Heparan Sulfate Proteoglycans; D046911:Macromolecular Substances