Niemann-Pick Type C disease: characterizing lipid levels in patients with variant lysosomal cholesterol storage.
A central feature of Niemann-Pick Type C (NPC) disease is sequestration of cholesterol and glycosphingolipids in lysosomes. A large phenotypic variability, on both a clinical as well as a molecular level, challenges NPC diagnosis. For example, substantial difficulties in identifying or excluding NPC in a patient exist in cases with a "variant" biochemical phenotype, where cholesterol levels in cultured fibroblasts, the primary diagnostic indicator, are only moderately elevated. Here we apply quantitative microscopy as an accurate and objective diagnostic tool to measure cholesterol accumulation at the level of single cells. When employed to characterize cholesterol enrichment in fibroblasts from 20 NPC patients and 11 controls, considerable heterogeneity became evident both within the population of cells cultured from one individual as well as between samples from different probands. An obvious correlation between biochemical phenotype and clinical disease course was not apparent from our dataset. However, plasma levels of HDL-cholesterol (HDL-c) tended to be in the normal range in patients with a "variant" as opposed to a "classic" biochemical phenotype. Attenuated lysosomal cholesterol accumulation in "variant" cells was associated with detectable NPC1 protein and residual capability to upregulate expression of ABCA1 in response to LDL. Taken together, our approach opens perspectives not only to support diagnosis, but also to better characterize mechanisms impacting cholesterol accumulation in NPC patient-derived cells.
Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.
Carolina
C
Tängemo
Dominik
D
Weber
Susanne
S
Theiss
Eugen
E
Mengel
Heiko
H
Runz
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000378:metabolism; D004252:DNA Mutational Analysis; D005372:Filipin; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008247:Lysosomes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics; D009154:Mutation; D000077296:Niemann-Pick C1 Protein; D052556:Niemann-Pick Disease, Type C / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D033921:Vesicular Transport Proteins
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D008076:Cholesterol, HDL; D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; C104585:NPC2 protein, human; D000077296:Niemann-Pick C1 Protein; D033921:Vesicular Transport Proteins; D005372:Filipin; D002784:Cholesterol
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