scholarly journals cAMP-mediated regulation of cholesterol accumulation in cystic fibrosis and Niemann-Pick type C cells

2008 ◽  
Vol 295 (5) ◽  
pp. L809-L819 ◽  
Author(s):  
Mary E. Manson ◽  
Deborah A. Corey ◽  
Nicole M. White ◽  
Thomas J. Kelley
Keyword(s):  
Cystic Fibrosis ◽  
Cellular Response ◽  
Cholesterol Accumulation ◽  
Camp Pathway ◽  
Model Cell ◽  
Type C ◽  
Niemann Pick ◽  
Primary Tissue ◽  
Independent Model

The goal of this study was to identify a mechanism regulating cholesterol accumulation in cystic fibrosis (CF) cells. Both CFTR activation and expression are regulated by the cAMP pathway, and it is hypothesized that a feedback response involving this pathway may be involved in the phenotype of cholesterol accumulation. To examine the role of the cAMP pathway in cholesterol accumulation, we treated two CF model cell lines with the Rp diastereomer of adenosine 3′,5′-cyclic monophosphorothioate ( Rp-cAMPS) and visualized by filipin staining. Rp-cAMPS treatment eliminated cholesterol accumulation in CF cells, whereas 8-bromo-cAMP treatment led to cholesterol accumulation in wild-type cells. To confirm these findings in an independent model system, we also examined the role of cAMP in modulating cholesterol accumulation in Niemann-Pick type C (NPC) fibroblasts. Expression of the protein related to NPC, NPC1, is also directly regulated by cAMP; therefore, it is postulated that NPC cells exhibit the same cAMP-mediated control of cholesterol accumulation. Cholesterol accumulation in NPC cells also was reduced by the presence of Rp-cAMPS. Expression of β-arrestin-2 (βarr2), a marker of cellular response to cAMP signaling, was significantly elevated in CF model cells, Cftr−/− MNE, primary tissue obtained by nasal scrapes from CF subjects, and in NPC fibroblasts compared with respective controls.

P0807 HEPATIC CHOLESTEROL ACCUMULATION IN THE NIEMANN-PICK TYPE C (NPC) MOUSE: REDUCTION WITH EZETIMIBE

2004 ◽  
Vol 39 (Supplement 1) ◽  
pp. S363-S364
Author(s):  
E. P. Beltroy ◽  
J. A. Richardson ◽  
J. D. Horton ◽  
S. D. Turley ◽  
J. M. Dietschy
Keyword(s):  
Hepatic Cholesterol ◽  
Cholesterol Accumulation ◽  
Type C ◽  
Niemann Pick ◽  
Npc Mouse

A High-Content RNAi-Screening Assay to Identify Modulators of Cholesterol Accumulation in Niemann–Pick Type C Cells

2010 ◽  
Vol 8 (3) ◽  
pp. 295-319 ◽  
Author(s):  
Shilpi Arora ◽  
Christian Beaudry ◽  
Kristen M. Bisanz ◽  
Chao Sima ◽  
Jeffrey A. Kiefer ◽  
...  
Keyword(s):  
C Cells ◽  
Cholesterol Accumulation ◽  
Screening Assay ◽  
Rnai Screening ◽  
Type C ◽  
Niemann Pick

scholarly journals Mutagenesis of the putative sterol-sensing domain of yeast Niemann Pick C–related protein reveals a primordial role in subcellular sphingolipid distribution

2004 ◽  
Vol 164 (4) ◽  
pp. 547-556 ◽  
Author(s):  
Krishnamurthy Malathi ◽  
Katsumi Higaki ◽  
Arthur H. Tinkelenberg ◽  
Dina A. Balderes ◽  
Dorca Almanzar-Paramio ◽  
...  
Keyword(s):  
Neurodegenerative Disorder ◽  
Chinese Hamster ◽  
Antibiotic Sensitivity ◽  
Cholesterol Accumulation ◽  
Transmembrane Glycoprotein ◽  
Lysosomal Accumulation ◽  
Type C ◽  
Niemann Pick ◽  
Sphingolipid Biosynthesis ◽  
Mutant Cells

Lipid movement between organelles is a critical component of eukaryotic membrane homeostasis. Niemann Pick type C (NP-C) disease is a fatal neurodegenerative disorder typified by lysosomal accumulation of cholesterol and sphingolipids. Expression of yeast NP-C–related gene 1 (NCR1), the orthologue of the human NP-C gene 1 (NPC1) defective in the disease, in Chinese hamster ovary NPC1 mutant cells suppressed lipid accumulation. Deletion of NCR1, encoding a transmembrane glycoprotein predominantly residing in the vacuole of normal yeast, gave no phenotype. However, a dominant mutation in the putative sterol-sensing domain of Ncr1p conferred temperature and polyene antibiotic sensitivity without changes in sterol metabolism. Instead, the mutant cells were resistant to inhibitors of sphingolipid biosynthesis and super sensitive to sphingosine and C2-ceramide. Moreover, plasma membrane sphingolipids accumulated and redistributed to the vacuole and other subcellular membranes of the mutant cells. We propose that the primordial function of these proteins is to recycle sphingolipids and that defects in this process in higher eukaryotes secondarily result in cholesterol accumulation.

scholarly journals Targeting defective sphingosine kinase 1 in Niemann–Pick type C disease with an activator mitigates cholesterol accumulation

2020 ◽  
Vol 295 (27) ◽  
pp. 9121-9133 ◽  
Author(s):  
Jason Newton ◽  
Elisa N. D. Palladino ◽  
Cynthia Weigel ◽  
Michael Maceyka ◽  
Markus H. Gräler ◽  
...  
Keyword(s):  
Specific Inhibitor ◽  
Sphingosine Kinase ◽  
Autophagic Flux ◽  
Sphingosine Kinase 1 ◽  
Cholesterol Trafficking ◽  
Cholesterol Accumulation ◽  
Cellular Models ◽  
Ester Formation ◽  
Type C ◽  
Niemann Pick

Niemann–Pick type C (NPC) disease is a lysosomal storage disorder arising from mutations in the cholesterol-trafficking protein NPC1 (95%) or NPC2 (5%). These mutations result in accumulation of low-density lipoprotein-derived cholesterol in late endosomes/lysosomes, disruption of endocytic trafficking, and stalled autophagic flux. Additionally, NPC disease results in sphingolipid accumulation, yet it is unique among the sphingolipidoses because of the absence of mutations in the enzymes responsible for sphingolipid degradation. In this work, we examined the cause for sphingosine and sphingolipid accumulation in multiple cellular models of NPC disease and observed that the activity of sphingosine kinase 1 (SphK1), one of the two isoenzymes that phosphorylate sphingoid bases, was markedly reduced in both NPC1 mutant and NPC1 knockout cells. Conversely, SphK1 inhibition with the isotype-specific inhibitor SK1-I in WT cells induced accumulation of cholesterol and reduced cholesterol esterification. Of note, a novel SphK1 activator (SK1-A) that we have characterized decreased sphingoid base and complex sphingolipid accumulation and ameliorated autophagic defects in both NPC1 mutant and NPC1 knockout cells. Remarkably, in these cells, SK1-A also reduced cholesterol accumulation and increased cholesterol ester formation. Our results indicate that a SphK1 activator rescues aberrant cholesterol and sphingolipid storage and trafficking in NPC1 mutant cells. These observations highlight a previously unknown link between SphK1 activity, NPC1, and cholesterol trafficking and metabolism.

Role of novel laboratory techniques in Niemann-Pick type C disease dia­gnostics

2020 ◽  
Vol 83/116 (3) ◽  
pp. 263-268
Author(s):  
Martin Hřebíček ◽  
Helena Jahnová ◽  
Lenka Dvořáková ◽  
Filip Majer ◽  
Dita Mušálková ◽  
...  
Keyword(s):  
Laboratory Techniques ◽  
Type C ◽  
Niemann Pick

scholarly journals Monitoring the itinerary of lysosomal cholesterol in Niemann-Pick Type C1-deficient cells after cyclodextrin treatment

2020 ◽  
Vol 61 (3) ◽  
pp. 403-412 ◽  
Author(s):  
McKenna Feltes ◽  
Sarah E. Gale ◽  
Samantha Moores ◽  
Daniel S. Ory ◽  
Jean E. Schaffer
Keyword(s):  
Isotope Labeling ◽  
Dependent Manner ◽  
Cholesterol Accumulation ◽  
Cholesterol Levels ◽  
Niemann Pick Disease ◽  
Genes Encoding ◽  
Type C ◽  
Niemann Pick ◽  
Lipid Storage Disorder ◽  
Pick Disease

Niemann-Pick disease type C (NPC) disease is a lipid-storage disorder that is caused by mutations in the genes encoding NPC proteins and results in lysosomal cholesterol accumulation. 2-Hydroxypropyl-β-cyclodextrin (CD) has been shown to reduce lysosomal cholesterol levels and enhance sterol homeostatic responses, but CD’s mechanism of action remains unknown. Recent work provides evidence that CD stimulates lysosomal exocytosis, raising the possibility that lysosomal cholesterol is released in exosomes. However, therapeutic concentrations of CD do not alter total cellular cholesterol, and cholesterol homeostatic responses at the ER are most consistent with increased ER membrane cholesterol. To address these disparate findings, here we used stable isotope labeling to track the movement of lipoprotein cholesterol cargo in response to CD in NPC1-deficient U2OS cells. Although released cholesterol was detectable, it was not associated with extracellular vesicles. Rather, we demonstrate that lysosomal cholesterol trafficks to the plasma membrane (PM), where it exchanges with lipoprotein-bound cholesterol in a CD-dependent manner. We found that in the absence of suitable extracellular cholesterol acceptors, cholesterol exchange is abrogated, cholesterol accumulates in the PM, and reesterification at the ER is increased. These results support a model in which CD promotes intracellular redistribution of lysosomal cholesterol, but not cholesterol exocytosis or efflux, during the restoration of cholesterol homeostatic responses.

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