title: Golgi apparatus and TGN during endocytosis.
abstract: Wheat germ agglutinin labelled with horseradish peroxidase (WGA) was used for analyses of endosomal compartments and Golgi apparatus in HepG(2) hepatoma cells during early and late periods of endocytosis. WGA was rapidly transferred into the Golgi region. Transport of internalised WGA into the Golgi apparatus could be classified in three stages. A short stage I, characterised by predominance of vesicular endosomes, was followed by stage II showing new formations of extended endocytic trans Golgi networks (TGNs); the endocytic TGNs comprised reticular and globular parts, showed intimate associations with segments of the endoplasmic reticulum and budding of multiple coated vesicles. Parts of the endocytic TGNs associated with trans Golgi cisternae and became integrated into Golgi stacks. During stage III, concomitantly with integration into the stacks, the endocytic TGNs decreased in size and stacked Golgi cisternae became prominent endocytic compartments. Our results show that endocytosis of WGA is connected with extensive membrane dynamics at the trans Golgi side: an endocytic TGN is newly formed, increases in size and is consumed again. The findings suggest that incorporation of TGN elements into Golgi stacks provides a mechanism for uptake of internalised WGA into the Golgi apparatus.
authors.affiliation: Institute of Histology and Embryology, Department of Cell Biology and Ultrastructure Research, University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Vetterlein
authors.forename: Adolf
authors.initials: A
authors.lastname: Ellinger
authors.forename: Josef
authors.initials: J
authors.lastname: Neumüller
authors.forename: Margit
authors.initials: M
authors.lastname: Pavelka
mesh_terms: D004705:Endocytosis / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D014407:Tumor Cells, Cultured; D014909:Wheat Germ Agglutinins / Q000737:chemistry / Q000378:metabolism
chemical_list: D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase