Browsing by Author "Zanlungo, Silvana"
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Item A Mouse Systems Genetics Approach Reveals Common and Uncommon Genetic Modifiers of Hepatic Lysosomal Enzyme Activities and Glycosphingolipids(2023) Durán, Anyelo; Priestman, David; Las Heras, Macarena; Rebolledo, Boris; Olguín, Valeria; Calderón, Juan; Zanlungo, Silvana; Gutiérrez, Jaime; Platt, Frances; Klein, AndrésIdentification of genetic modulators of lysosomal enzyme activities and glycosphingolipids (GSLs) may facilitate the development of therapeutics for diseases in which they participate, including Lysosomal Storage Disorders (LSDs). To this end, we used a systems genetics approach: we measured 11 hepatic lysosomal enzymes and many of their natural substrates (GSLs), followed by modifier gene mapping by GWAS and transcriptomics associations in a panel of inbred strains. Unexpectedly, most GSLs showed no association between their levels and the enzyme activity that catabolizes them. Genomic mapping identified 30 shared predicted modifier genes between the enzymes and GSLs, which are clustered in three pathways and are associated with other diseases. Surprisingly, they are regulated by ten common transcription factors, and their majority by miRNA-340p. In conclusion, we have identified novel regulators of GSL metabolism, which may serve as therapeutic targets for LSDs and may suggest the involvement of GSL metabolism in other pathologies.Item c-Abl Inhibition Activates TFEB and Promotes Cellular Clearance in a Lysosomal Disorder(Cell Press, 2020) Contreras, Pablo; Tapia, Pablo; González-Hodar, Lila; Peluso, Ivana; Soldati, Chiara; Napoiotano, Gennaro; Matarese, María; Las Heras, Macarena; Valls, Cristian; Martínez, Alexis; Balboa, Elisa; Castro, Juan; Nancy, Leal; Platt, Frances; Sobota, Andrzej; Winter, Dominic; Klein, Andrés; Medina, Diego; Ballabio, Andrea; Alvarez, Alejandra; Zanlungo, SilvanaThe transcription factor EB (TFEB) has emerged as a master regulator of lysosomal biogenesis, exocytosis, and autophagy, promoting the clearance of substrates stored in cells. c-Abl is a tyrosine kinase that participates in cellular signaling in physiological and pathophysiological conditions. In this study, we explored the connection between c-Abl and TFEB. Here, we show that under pharmacological and genetic c-Abl inhibition, TFEB translocates into the nucleus promoting the expression of its target genes independently of its well-known regulator, mammalian target of rapamycin complex 1. Active c-Abl induces TFEB phosphorylation on tyrosine and the inhibition of this kinase promotes lysosomal biogenesis, autophagy, and exocytosis. c-Abl inhibition in Niemann-Pick type C (NPC) models, a neurodegenerative disease characterized by cholesterol accumulation in lysosomes, promotes a cholesterol-lowering effect in a TFEB-dependent manner. Thus, c-Abl is a TFEB regulator that mediates its tyrosine phosphorylation, and the inhibition of c-Abl activates TFEB promoting cholesterol clearance in NPC models.Item Complement Component C3 Participates in Early Stages of Niemann-Pick C Mouse Liver Damage(MDPI AG, 2020) Klein, Andrés; González, Javier; Zanlungo, SilvanaNiemann-Pick type C (NPC), a lysosomal storage disorder, is mainly caused by mutations in the NPC1 gene. Niemann-Pick type C patients and mice show intracellular cholesterol accumulation leading to hepatic failure with increased inflammatory response. The complement cascade, which belongs to the innate immunity response, recognizes danger signals from injured tissues. We aimed to determine whether there is activation of the complement system in the liver of the NPC mouse and to assess the relationship between C3 activation, a final component of the pathway, and NPC liver pathology. Niemann-Pick type C mice showed high levels of C3 staining in the liver which unexpectedly decreased with aging. Using an inducible NPC1 hepatocyte rescue mouse model, we restored NPC1 expression for a short time in young mice. We found C3 positive cells only in non-rescued cells, suggesting that C3 activation in NPC cells is reversible. Then, we studied the effect of C3 ablation on NPC liver damage at two postnatal time points, P56 and P72. Deletion of C3 reduced the presence of hepatic CD68-positive cells at postnatal day 56 and prevented the increase of transaminase levels in the blood of NPC mice. These positive effects were abrogated at P72, indicating that the complement cascade participates only during the early stages of liver damage in NPC mice, and that its inhibition may serve as a new potential therapeutic strategy for the disease.Item Gadolinium Chloride Rescues Niemann–Pick Type C Liver Damage(2018) Klein, Andrés; Oyarzún, Juan Esteban; Cortez, Cristian; Zanlungo, SilvanaNiemann–Pick type C (NPC) disease is a rare neurovisceral cholesterol storage disorder that arises from loss of function mutations in the NPC1 or NPC2 genes. Soon after birth, some patients present with an aggressive hepatosplenomegaly and cholestatic signs. Histopathologically, the liver presents with large numbers of foam cells; however, their role in disease pathogenesis has not been explored in depth. Here, we studied the consequences of gadolinium chloride (GdCl3) treatment, a well-known Kupffer/foam cell inhibitor, at late stages of NPC liver disease and compared it with NPC1 genetic rescue in hepatocytes in vivo. GdCl3 treatment successfully blocked the endocytic capacity of hepatic Kupffer/foam measured by India ink endocytosis, decreased the levels CD68—A marker of Kupffer cells in the liver—and normalized the transaminase levels in serum of NPC mice to a similar extent to those obtained by genetic Npc1 rescue of liver cells. Gadolinium salts are widely used as magnetic resonance imaging (MRI) contrasts. This study opens the possibility of targeting foam cells with gadolinium or by other means for improving NPC liver disease. Synopsis: Gadolinium chloride can effectively rescue some parameters of liver dysfunction in NPC mice and its potential use in patients should be carefully evaluatedItem Identification of genetic modifiers of murine hepatic β-glucocerebrosidase activity(2021) Durán, Anyelo; Rebolledo-Jaramillo, Boris; Olguin, Valeria; Rojas-Herrera, Marcelo; Las Heras, Macarena; Calderón, Juan F.; Zanlungo, Silvana; Priestman, David A.; Platt, Frances M.; Klein, AndrésThe acid β-glucocerebrosidase (GCase) enzyme cleaves glucosylceramide into glucose and ceramide. Loss of function variants in the gene encoding for GCase can lead to Gaucher disease and Parkinson’s disease. Therapeutic strategies aimed at increasing GCase activity by targeting a modulating factor are attractive and poorly explored. To identify genetic modifiers, we measured hepatic GCase activity in 27 inbred mouse strains. A genome-wide association study (GWAS) using GCase activity as a trait identified several candidate modifier genes, including Dmrtc2 and Arhgef1 (p=2.1x10− 7 ), and Grik5 (p=2.1x10− 7 ). Bayesian integration of the gene mapping with transcriptomics was used to build integrative networks. The analysis uncovered additional candidate GCase regulators, highlighting modules of the acute phase response (p=1.01x10− 8 ), acute inflammatory response (p=1.01x10− 8 ), fatty acid beta-oxidation (p=7.43x10− 5 ), among others. Our study revealed previously unknown candidate modulators of GCase activity, which may facilitate the design of therapies for diseases with GCase dysfunction.Item Lack of Annexin A6 exacerbates liver dysfunction and reduces lifespan of NPC1- deficient mice(Elsevier Inc./ American Society for Investigative Pathology, 2020) Meneses-Salas, Elsa; Garcia-Forn, Marta; Castany-Pladevall, Carla; Lu, Albert; Fajardo, Alba; José, Jaimy; Wahba, Mohamed; Bosch, Marta; Pol, Albert; Tebar, Francesc; Klein, Andrés; Zanlungo, Silvana; Pérez-Navarro, Esther; Grewal, Thomas; Enrich, Carlos; Rentero, CarlesNiemann-Pick type C disease (NP-C) is a lysosomal storage disorder characterized by cholesterol accumulation caused by loss-of-function mutations in the Npc1 gene. NP-C disease primarily affects the brain, causing neuronal damage and affecting motor coordination. In addition, considerable liver malfunction in NP-C disease is common. Recently, we demonstrated that the depletion of annexin A6 (ANXA6), which is most abundant in the liver and involved in cholesterol transport, ameliorated cholesterol accumulation in Npc1 mutant cells. To evaluate the potential contribution of ANXA6 in the progression of NP-C disease, double-knockout mice (Npc1-/-/Anxa6-/-) were generated and examined for lifespan, neurological and hepatic functions, as well as liver histology and ultrastructure. Strikingly, lack of ANXA6 in NPC1-deficient animals did not prevent the cerebellar degeneration phenotype but further deteriorated their compromised hepatic functions and reduced lifespan. Moreover, livers of Npc1-/-/Anxa6-/- mice contained a significantly elevated number of foam cells congesting the sinusoidal space, a feature commonly associated with inflammation. We hypothesize that ANXA6 deficiency in Npc1-/- mice do not reverse neurological and motor dysfunction and it further worsens overall liver function, exacerbating hepatic failure in NP-C disease.Item Proteomic Analysis of Niemann-Pick Type C Hepatocytes Reveals Potential Therapeutic Targets for Liver Damage(2021) Balboa, Elisa; Marín, Tamara; Oyarzún, Juan Esteban; Contreras, Pablo S.; Hardt, Robert; Bosch, Thea van den; Alvarez, Alejandra R.; Rebolledo-Jaramillo, Boris; Klein, Andrés; Winter, Dominic; Zanlungo, SilvanaNiemann-Pick type C disease (NPCD) is a lysosomal storage disorder caused by mutations in the NPC1 gene. The most affected tissues are the central nervous system and liver, and while significant efforts have been made to understand its neurological component, the pathophysiology of the liver damage remains unclear. In this study, hepatocytes derived from wild type and Npc1−/− mice were analyzed by mass spectrometry (MS)-based proteomics in conjunction with bioinformatic analysis. We identified 3832 proteins: 416 proteins had a p-value smaller than 0.05, of which 37% (n = 155) were considered differentially expressed proteins (DEPs), 149 of them were considered upregulated, and 6 were considered downregulated. We focused the analysis on pathways related to NPC pathogenic mechanisms, finding that the most significant changes in expression levels occur in proteins that function in the pathways of liver damage, lipid metabolism, and inflammation. Moreover, in the group of DEPs, 30% (n = 47) were identified as lysosomal proteins and 7% (n = 10) were identified as mitochondrial proteins. Importantly, we found that lysosomal DEPs, including CTSB/D/Z, LIPA, DPP7 and GLMP, and mitocondrial DEPs, AKR1B10, and VAT1 had been connected with liver fibrosis, damage, and steatosis in previous studies, validiting our dataset. Our study found potential therapeutic targets for the treatment of liver damage in NPCDPublication Understanding the phenotypic variability in Niemann-Pick disease type C (NPC): a need for precision medicine(2023) Las Heras, Macarena; Szenfeld, Benjamín; Ballout, Rami A.; Buratti, Emanuele; Zanlungo, Silvana; Dardis, Andrea; KLEIN, ANDRESNiemann-Pick type C (NPC) disease is a lysosomal storage disease (LSD) characterized by the buildup of endo-lysosomal cholesterol and glycosphingolipids due to loss of function mutations in the NPC1 and NPC2 genes. NPC patients can present with a broad phenotypic spectrum, with differences at the age of onset, rate of progression, severity, organs involved, effects on the central nervous system, and even response to pharmacological treatments. This article reviews the phenotypic variation of NPC and discusses its possible causes, such as the remaining function of the defective protein, modifier genes, sex, environmental cues, and splicing factors, among others. We propose that these factors should be considered when designing or repurposing treatments for this disease. Despite its seeming complexity, this proposition is not far-fetched, considering the expanding interest in precision medicine and easier access to multi-omics technologies.