title: Intracellular fate of octaarginine-modified liposomes in polarized MDCK cells.
abstract: Octaarginine (R8)-modified liposomes have been used to deliver therapeutic substances into cells owing to the efficient cellular uptake via macropinocytosis. Recent analyses revealed that R8-modified liposomes are mainly taken up via macropinocytosis, and escape from endosomes efficiently to avoid lysosomal degradation in non-polarized NIH-3T3 cells. In the present study, we evaluated the intracellular fate of R8-modified liposomes in polarized MDCK cells, comparing their trafficking with that of conventional cationic liposomes by confocal laser scanning microscopy (CLSM). In contrast to what occurs in NIH-3T3 cells, R8-modified liposomes are internalized by MDCK cells equally well via clathrin-mediated endocytosis and macropinocytosis. The most salient characteristic in subsequent intracellular trafficking in MDCK cells is that R8-modified liposomes become trapped in the endosomal compartment and subsequently, a portion of them colocalizes with the Golgi apparatus. Similar colocalization with the Golgi apparatus was observed for octalysine (K8)-modified liposomes. In contrast, cationic liposomes were found to colocalize predominantly with lysosomes stained with lysotracker. Collectively, in polarized MDCK cells, cationic peptide-modified liposomes may be subjected to a different sorting pathway from that used for liposomes composed of cationic lipids.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Akita
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
mesh_terms: D000818:Animals; D001692:Biological Transport; D002412:Cations; D002460:Cell Line; D016764:Cell Polarity; D002626:Chemistry, Pharmaceutical; D002966:Clathrin / Q000378:metabolism; D004285:Dogs; D004339:Drug Compounding; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism*; D010316:Particle Size; D010750:Phosphoproteins / Q000378:metabolism; D010873:Pinocytosis; D013678:Technology, Pharmaceutical / Q000379:methods; D014162:Transfection; D062826:Zonula Occludens-1 Protein
chemical_list: D002412:Cations; D002966:Clathrin; D008055:Lipids; D008081:Liposomes; D008565:Membrane Proteins; D009842:Oligopeptides; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; C448619:octaarginine; D049452:Green Fluorescent Proteins