title: Endocytic pathway of high density lipoprotein via trans-Golgi system in rat resident peritoneal macrophages.
abstract: Interaction of high density lipoprotein (HDL) with rat resident peritoneal macrophages was investigated by morphological and biochemical approaches. Binding studies at 0 degree C demonstrated saturable binding sites for 125I-HDL on the surface membrane. When cells were incubated with 125I-HDL at 37 degrees C, the cell-associated radioactivity increased with time, but intracellular degradation of HDL did not occur. Rather, the cell-associated 125I-HDL was released intact into the medium. Two morphological probes were employed to visualize the post-binding fate of HDL. Horseradish peroxidase and ferritin conjugates of HDL showed specific bindings to the coated pits of the plasma membranes and were internalized and delivered through receptosomes to a trans-Golgi system. They were then resecreted as secretory vesicles from the cells. Parallel experiments with transferrin-horseradish peroxidase conjugates revealed an endocytic pathway identical or very similar to that observed with HDL. These results provide evidence that internalization and subsequent nonlysosomal pathway via the trans-Golgi system are involved in receptor-mediated endocytosis of HDL by macrophages.
authors.affiliation: Department of Pathology, Kumamoto University Medical School, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: S
authors.initials: S
authors.lastname: Fukuda
authors.forename: M
authors.initials: M
authors.lastname: Naito
authors.forename: S
authors.initials: S
authors.lastname: Horiuchi
authors.forename: K
authors.initials: K
authors.lastname: Takata
authors.forename: Y
authors.initials: Y
authors.lastname: Morino
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D004705:Endocytosis; D006056:Golgi Apparatus / Q000378:metabolism*; D006651:Histocytochemistry; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D010537:Peritoneum / Q000166:cytology; D016601:RNA-Binding Proteins; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism; D018110:Receptors, Lipoprotein
chemical_list: D002352:Carrier Proteins; D008075:Lipoproteins, HDL; D016601:RNA-Binding Proteins; D011956:Receptors, Cell Surface; D018110:Receptors, Lipoprotein; C031616:high density lipoprotein receptors; C075197:high density lipoprotein binding protein