Recycling compartments and the internal vesicles of multivesicular bodies harbor most of the cholesterol found in the endocytic pathway.
We employed our recently developed immuno-electron microscopic method (W. Möbius, Y. Ohno-Iwashita, E. G. van Donselaar, V. M. Oorschot, Y. Shimada, T. Fujimoto, H. F. Heijnen, H. J. Geuze and J. W. Slot, J Histochem Cytochem 2002; 50: 43-55) to analyze the distribution of cholesterol in the endocytic pathway of human B lymphocytes. We could distinguish 6 categories of endocytic compartments on the basis of morphology, BSA gold uptake kinetics and organelle marker analysis. Of all cholesterol detected in the endocytic pathway, we found 20% in the recycling tubulo-vesicles and 63% present in two types of multivesicular bodies. In the multivesicular bodies, most of the cholesterol was contained in the internal membrane vesicles, the precursors of exosomes secreted by B cells. Cholesterol was almost absent from lysosomes, that contained the bulk of the lipid bis(monoacylglycero)phosphate, also termed lysobisphosphatidic acid. Thus, cholesterol displays a highly differential distribution in the various membrane domains of the endocytic pathway.
Möbius
W
W
Department of Cell Biology and Institute of Biomembranes and Center for Biomedical Genetics, University Medical Center Utrecht, the Netherlands. w.moebius@lab.azu.nl
van Donselaar
E
E
Ohno-Iwashita
Y
Y
Shimada
Y
Y
Heijnen
H F G
HF
Slot
J W
JW
Geuze
H J
HJ
D002461:Cell Line, Transformed; D002784:Cholesterol / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D006046:Gold / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008247:Lysosomes / Q000378:metabolism / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D012710:Serum Albumin, Bovine / Q000378:metabolism
D012710:Serum Albumin, Bovine; D006046:Gold; D002784:Cholesterol