Cholesterol Pathways Affected by Small Molecules That Decrease Sterol Levels in Niemann-Pick Type C Mutant Cells

Abstract

BackgroundNiemann-Pick type C (NPC) disease is a genetically inherited multi-lipid storage disorder with impaired efflux of cholesterol from lysosomal storage organelles.Methodology/Principal FindingsThe effect of screen-selected cholesterol lowering compounds on the major sterol pathways was studied in CT60 mutant CHO cells lacking NPC1 protein. Each of the selected chemicals decreases cholesterol in the lysosomal storage organelles of NPC1 mutant cells through one or more of the following mechanisms: increased cholesterol efflux from the cell, decreased uptake of low-density lipoproteins, and/or increased levels of cholesteryl esters. Several chemicals promote efflux of cholesterol to extracellular acceptors in both non-NPC and NPC1 mutant cells. The uptake of low-density lipoprotein-derived cholesterol is inhibited by some of the studied compounds.Conclusions/SignificanceResults herein provide the information for prioritized further studies in identifying molecular targets of the chemicals. This approach proved successful in the identification of seven chemicals as novel inhibitors of lysosomal acid lipase (Rosenbaum et al, Biochim. Biophys. Acta. 2009, 1791:1155–1165).

Histone deacetylase inhibitor treatment dramatically reduces cholesterol accumulation in Niemann-Pick type C1 mutant human fibroblasts

“…14 C]-oleic acid incorporation into cholesteryl-[ 14 C]-oleate as described (34). NPC1 mutant fibroblasts GM03123 were treated with HDACi at their most effective concentration for 48 h. LBH589 treatment (40 nM) resulted in a 2.5-fold increase in ACAT-mediated esterification compared with DMSOtreated control cells (Fig.…”

Fluorescence image screening for chemical compounds modifying cholesterol metabolism and distribution

“…Selection of cell type and domain 4 fragment of toxin to detect subtle alteration of cell surface cholesterol Recently, Maxfi eld and coworkers employed fi lipin for automated microscopy screening and discovered compounds that partially revert cholesterol accumulation in Niemann-Pick C cells ( 12,14 ). Similar to fi lipin, toxin specifi cally binds cholesterol ( 16 ).…”

“…Filipin has been employed in detecting cellular cholesterol distribution ( 13 ). The microscopy screening using fi lipin identifi ed several compounds that decrease cholesterol accumulation in the late endosomes of Niemann-Pick C cells ( 12,14 ). Because fi lipin penetrates the membrane, this antibiotic cannot be used to selectively label the plasma membrane.…”

4-hydroxytamoxifen leads to PrPSc clearance by conveying both PrPC and PrPSc to lysosomes independently of autophagy

“…Therefore, it seems very likely that the effects observed are related to the amphipathic weak base properties and do not rely on the oestrogen-receptor-binding characteristics of tamoxifen. Also, it has been shown that changes related to lysosomal cholesterol accumulation as a result of NPC mutations or amphipathic weak base treatment alter the trafficking of many membrane components (Choudhury et al, 2004;Mukherjee and Maxfield, 2004;Rujoi et al, 2010). Therefore, although TAM represents a wellcharacterized, widely available pharmaceutical that may have applications as a broad-spectrum therapy for prion diseases, drugs sharing weak amphipathic bases properties with less selective biological effect than tamoxifen could be tested as possible candidates in the therapy for these diseases.…”