Sterol-modulated glycolipid sorting occurs in niemann-pick C1 late endosomes.
The Niemann-Pick C1 (NPC1) protein and endocytosed low density lipoprotein (LDL)-derived cholesterol were shown to enrich separate subsets of vesicles containing lysosomal associated membrane protein 2. Localization of Rab7 in the NPC1-containing vesicles and enrichment of lysosomal hydrolases in the cholesterol-containing vesicles confirmed that these organelles were late endosomes and lysosomes, respectively. Lysobisphosphatidic acid, a lipid marker of the late endosomal pathway, was found in the cholesterol-enriched lysosomes. Recruitment of NPC1 to Rab7 compartments was stimulated by cellular uptake of cholesterol. The NPC1 compartment was shown to be enriched in glycolipids, and internalization of GalNAcbeta1-4[NeuAcalpha2-3]Galbeta1-4Glcbeta1-1'-ceramide (G(M2)) into endocytic vesicles depends on the presence of NPC1 protein. The glycolipid profiles of the NPC1 compartment could be modulated by LDL uptake and accumulation of lysosomal cholesterol. Expression in cells of biologically active NPC1 protein fused to green fluorescent protein revealed rapidly moving and flexible tubular extensions emanating from the NPC1-containing vesicles. We conclude that the NPC1 compartment is a dynamic, sterol-modulated sorting organelle involved in the trafficking of plasma membrane-derived glycolipids as well as plasma membrane and endocytosed LDL cholesterol.
Zhang
M
M
Lipid Cell Biology Section and Cell Biochemistry Section, Laboratory of Cell Biochemistry and Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Dwyer
N K
NK
Neufeld
E B
EB
Love
D C
DC
Cooney
A
A
Comly
M
M
Patel
S
S
Watari
H
H
Strauss
J F
JF
Pentchev
P G
PG
Hanover
J A
JA
Blanchette-Mackie
E J
EJ
D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D011992:Endosomes / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism*; D006651:Histocytochemistry; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008077:Lipoproteins, LDL; D008247:Lysosomes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D000077296:Niemann-Pick C1 Protein; D021381:Protein Transport / Q000502:physiology; D013347:Subcellular Fractions; D014162:Transfection
D002352:Carrier Proteins; D018076:DNA, Complementary; D006017:Glycolipids; D047908:Intracellular Signaling Peptides and Proteins; D008077:Lipoproteins, LDL; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; D002784:Cholesterol