Clathrin-independent endocytosis contributes to uptake of glucose into BY-2 protoplasts.
In eukaryotic cells, several pathways exist for the internalization of plasma membrane proteins and extracellular cargo molecules. These endocytic pathways can be divided into clathrin-dependent and clathrin-independent pathways. While clathrin-dependent pathways are known to be involved in a variety of cellular processes in plants, clathrin-independent pathways have so far only been identified in animal and yeast cells. Here we show that internalization of fluorescent glucose into BY-2 cells leads to accumulation of the sugar in compartments of the endocytic pathway. This endocytic uptake of glucose was not blocked by ikarugamycin, an inhibitor of clathrin-dependent endocytosis, suggesting a role for clathrin-independent endocytosis in glucose uptake. Investigations of fusion and fission of single vesicles by membrane capacitance measurements revealed stimulation of endocytic activity by extracellular glucose. Glucose-stimulated fission of vesicles was not affected by addition of ikarugamycin or blocking of clathrin coat formation by transient over-expression of HUB1 (the C-terminal part of the clathrin heavy chain). These data demonstrate that clathrin-independent endocytosis does occur in plant cells. This pathway may represent a common mechanism for the uptake of external nutrients.
Institut für Botanik, Technische Universität Darmstadt, Schnittspahnstraße 3-5, Darmstadt, Germany.
Vera
V
Bandmann
Ulrike
U
Homann
D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D033922:Clathrin Heavy Chains / Q000235:genetics / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007769:Lactams / Q000494:pharmacology; D018613:Microscopy, Confocal; D011523:Protoplasts / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology* / Q000378:metabolism; D014162:Transfection; D014617:Vacuoles / Q000378:metabolism
D007769:Lactams; D033922:Clathrin Heavy Chains; D049452:Green Fluorescent Proteins; C074292:ikarugamycin; D003847:Deoxyglucose; D009327:4-Chloro-7-nitrobenzofurazan; D005947:Glucose; C098340:2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose