scholarly journals Role of Autophagy in Phosphatidyl- Glycerol Facilitated Cholesterol Clearance from the Endolysosomal System of Npc-1 Deficient Cells

Author(s):  
Tamara Allada ◽  
Olga Ilnytska ◽  
Judith Storch

Niemann Pick Type C (NPC) Disease is a rare lysosomal storage disorder in which one of the genes that codes for either the NPC-1 or NPC-2 pro-tein is mutated, causing cell lysosomes to accumu-late cholesterol and lipids. Previous studies discov-ered that a unique late endosomal/lysosomal phos-pholipid, lysobisphosphatidic acid (LPBA), is in-volved in cholesterol clearance from late endo-somes. It has also been shown that exogenous treat-ment of the NPC-1 deficient cells with LBPA’s precur-sor, phosphatidylglycerol (PG), leads to LBPA enrich-ment and subsequent endolysosomal cholesterol clearance. Autophagy is a mechanism of cellular clearance in the endolysomal system and we are in-terested to see if it is a partial route in cholesterol clearance during PG treatment of NPC-1 deficient cells. To do so, we silenced the gene that codes for an essential protein in the autophagy pathway, mak-ing the cells autophagy deficient. We then treated the cells with PG, measured the amount of choles-terol clearance in those cells, and compared it to cells with normal autophagy. We found significantly less cholesterol clearance by PG in cells with defec-tive autophagy, confirming that autophagy is in-volved as a partial route in cholesterol clearance dur-ing PG treatment, but not enough of a difference to conclude that it is a major underlying mechanism.

2021 ◽  
Vol 10 (20) ◽  
pp. 4796
Author(s):  
Andrea Dardis ◽  
Eleonora Pavan ◽  
Martina Fabris ◽  
Rosalia Maria Da Riol ◽  
Annalisa Sechi ◽  
...  

(1) Background: Niemann–Pick type C disease (NPCD) is an autosomal recessive lysosomal storage disorder caused by mutations in the NPC1 or NPC2 genes. The clinical presentation is characterized by visceral and neurological involvement. Apart from a small group of patients presenting a severe perinatal form, all patients develop progressive and fatal neurological disease with an extremely variable age of onset. Different biomarkers have been identified; however, they poorly correlate with neurological disease. In this study we assessed the possible role of plasma NfL as a neurological disease-associated biomarker in NPCD. (2) Methods: Plasma NfL levels were measured in 75 healthy controls and 26 patients affected by NPCD (24 NPC1 and 2 NPC2; 39 samples). (3) Results: Plasma NfL levels in healthy controls correlated with age and were significantly lower in pediatric patients as compared to adult subjects (p = 0.0017). In both pediatric and adult NPCD patients, the plasma levels of NfL were significantly higher than in age-matched controls (p < 0.0001). Most importantly, plasma NfL levels in NPCD patients with neurological involvement were significantly higher than the levels found in patients free of neurological signs at the time of sampling, both in the pediatric and the adult group (p = 0.0076; p = 0.0032, respectively). Furthermore, in adults the NfL levels in non-neurological patients were comparable with those found in age-matched controls. No correlations between plasma NfL levels and NPCD patient age at sampling or plasma levels of cholestan 3β-5α-6β-triol were found. (4) Conclusions: These data suggest a promising role of plasma NfL as a possible neurological disease-associated biomarker in NPCD.


2012 ◽  
Vol 42 (7) ◽  
pp. 1886-1892 ◽  
Author(s):  
Anneliese O. Speak ◽  
Nicholas Platt ◽  
Mariolina Salio ◽  
Danielle te Vruchte ◽  
David A. Smith ◽  
...  

2020 ◽  
Vol 11 (12) ◽  
Author(s):  
Seung-Eun Lee ◽  
Nari Shin ◽  
Myung Geun Kook ◽  
Dasom Kong ◽  
Nam Gyo Kim ◽  
...  

AbstractRecent studies on developing three-dimensional (3D) brain organoids from stem cells have allowed the generation of in vitro models of neural disease and have enabled the screening of drugs because these organoids mimic the complexity of neural tissue. Niemann-Pick disease, type C (NPC) is a neurodegenerative lysosomal storage disorder caused by mutations in the NPC1 or NPC2. The pathological features underlying NPC are characterized by the abnormal accumulation of cholesterol in acidic compartments, including late endosomes and lysosomes. Due to the inaccessibility of brain tissues from human NPC patients, we developed NPC brain organoids with induced neural stem cells from NPC patient-derived fibroblasts. NPC organoids exhibit significantly reduced size and proliferative ability, which are accompanied by accumulation of cholesterol, impairment in neuronal differentiation, and autophagic flux and dysfunction of lysosomes; therefore, NPC organoids can recapitulate the main phenotypes of NPC patients. Furthermore, these pathological phenotypes observed in NPC organoids were reversed by treatment with valproic acid and HPBCD, which are known to be an effective treatment for several neurodegenerative diseases. Our data present patient-specific phenotypes in 3D organoid-based models of NPC and highlight the application of this model to drug screening in vitro.


2008 ◽  
Vol 295 (5) ◽  
pp. L809-L819 ◽  
Author(s):  
Mary E. Manson ◽  
Deborah A. Corey ◽  
Nicole M. White ◽  
Thomas J. Kelley

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.


2015 ◽  
Vol 396 (6-7) ◽  
pp. 659-667 ◽  
Author(s):  
Einat B. Vitner ◽  
Anthony H. Futerman ◽  
Nick Platt

Abstract Lysosomal storage diseases (LSDs) are mainly caused by the defective activity of lysosomal hydrolases. A sub-class of LSDs are the sphingolipidoses, in which sphingolipids accumulate intra-cellularly. We here discuss the role of innate immunity in the sphingolipidoses, and compare the pathways of activation in two classical sphingolipidoses, namely Gaucher disease and Sandhoff disease, and in Niemann-Pick C disease, in which the main storage material is cholesterol but sphingolipids also accumulate. We discuss the mechanisms leading to neuroinflammation, and the different pathways of neuroinflammation in the different diseases, and suggest that intervention in these pathways may be a useful therapeutic approach to address these devastating human diseases.


2000 ◽  
Vol 11 (5) ◽  
pp. 1829-1843 ◽  
Author(s):  
Toshihide Kobayashi ◽  
Ulrich M. Vischer ◽  
Corinne Rosnoblet ◽  
Cécile Lebrand ◽  
Margaret Lindsay ◽  
...  

In the present study, we show that in human endothelial cells the tetraspanin CD63/lamp3 distributes predominantly to the internal membranes of multivesicular–multilamellar late endosomes, which contain the unique lipid lysobisphosphatidic acid. Some CD63/lamp3 is also present in Weibel–Palade bodies, the characteristic secretory organelle of these cells. We find that CD63/lamp3 molecules can be transported from late endosomes to Weibel–Palade bodies and thus that CD63/lamp3 cycles between endocytic and biosynthetic compartments; however, movement of CD63/lamp3 is much slower than that of P-selectin, which is known to cycle between plasma membrane and Weibel–Palade bodies. When cells are treated with U18666A, a drug that mimics the Niemann-Pick type C syndrome, both proteins accumulate in late endosomes and fail to reach Weibel–Palade bodies efficiently, suggesting that P-selectin, like CD63/lamp3, cycles via late endosomes. Our data suggest that CD63/lamp3 partitions preferentially within late endosome internal membranes, thus causing its accumulation, and that this mechanism contributes to CD63/lamp3 retention in late endosomes; however, our data also indicate that the protein can eventually escape from these internal membranes and recycle toward Weibel–Palade bodies to be reused. Our observations thus uncover the existence of a selective trafficking route from late endosomes to Weibel–Palade bodies.


2017 ◽  
Vol 2 ◽  
pp. 75 ◽  
Author(s):  
William R.H. Evans ◽  
Elena-Raluca Nicoli ◽  
Raymond Y. Wang ◽  
Nina Movsesyan ◽  
Frances M. Platt

In this case series, we demonstrate that Ursodeoxycholic acid (UDCA) improves liver dysfunction in Niemann-Pick type C (NPC) and may restore a suppressed cytochrome p450 system. NPC disease is a progressive neurodegenerative lysosomal storage disease caused by mutations in either the NPC1 or NPC2 genes. Liver disease is a common feature presenting either acutely as cholestatic jaundice in the neonatal period, or in later life as elevated liver enzymes indicative of liver dysfunction. Recently, an imbalance in bile acid synthesis in a mouse model of NPC disease was linked to suppression of the P450 detoxification system and was corrected by UDCA treatment. UDCA (3α, 7β-dihydroxy-5β-cholanic acid), a hydrophilic bile acid, is used to treat various cholestatic disorders. In this report we summarise the findings from four independent cases of NPC, three with abnormal liver enzyme levels at baseline, that were subsequently treated with UDCA. The patients differed in age and clinical features, they all tolerated the drug well, and in those with abnormal liver function, there were significant improvements in their liver enzyme parameters.


Author(s):  
Rami Ballout

In the face of the newly emergent COVID-19 pandemic, researchers around the world are racing to identify efficacious drugs capable of preventing or treating its infection. They are doing that by testing already available and approved antimicrobials for their rapid repurposing against COVID-19. Using the data emerging on the comparable efficacy of various compounds having different mechanisms of action and indications, I suggest in this report, their potential mechanistic convergence. Specifically, I highlight the lysosome as a key possible therapeutic target for COVID-19, proposing one of the lysosomal storage disorders, Niemann-Pick type C disease (NPC), as a prototypical condition with inherent resistance or an &ldquo;unfavorable&rdquo; host cell environment for viral propagation. The included reasoning evolves from previously generated data in NPC, along with the emerging data on COVID-19. The aim of this report is to suggest that pharmacological induction of a &ldquo;transient&rdquo; NPC-like lysosomal dysfunction, could hold answers for targeting the ongoing COVID-19 pandemic.


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