Browsing by Author "Marín Marín, Tamara Alejandra"
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- Itemc-Abl activates RIPK3 signaling in Gaucher disease(2021) Yañez Henríquez, María José; Campos, F.; Marín Marín, Tamara Alejandra; Klein Posternack, Andrés David; Futerman, A. H.; Álvarez, Alejandra R.; Zanlungo Matsuhiro, SilvanaGaucher disease (GD) is caused by homozygous mutations in the GBA1 gene, which encodes the lysosomal β-glucosidase (GBA) enzyme. GD affects several organs and tissues, including the brain in certain variants of the disease. Heterozygous GBA1 variants are a major genetic risk factor for developing Parkinson's disease. The RIPK3 kinase is relevant in GD and its deficiency improves the neurological and visceral symptoms in a murine GD model. RIPK3 mediates necroptotic-like cell death: it is unknown whether the role of RIPK3 in GD is the direct induction of necroptosis or if it has a more indirect function by mediating necrosis-independent. Also, the mechanisms that activate RIPK3 in GD are currently unknown. In this study, we show that c-Abl tyrosine kinase participates upstream of RIPK3 in GD. We found that the active, phosphorylated form of c-Abl is increased in several GD models, including patient's fibroblasts and GBA null mice. Furthermore, its pharmacological inhibition with the FDA-approved drug Imatinib decreased RIPK3 signaling. We found that c-Abl interacts with RIPK3, that RIPK3 is phosphorylated at a tyrosine site, and that this phosphorylation is reduced when c-Abl is inhibited. Genetic ablation of c-Abl in neuronal GD and GD mice models significantly reduced RIPK3 activation and MLKL downstream signaling. These results showed that c-Abl signaling is a new upstream pathway that activates RIPK3 and that its inhibition is an attractive therapeutic approach for the treatment of GD.
- ItemC-ABL kinase in Niemann Pick type a disease : its implication in the pathogenic mechanisms leading to autophagic flux alterations and neurodegeneration.(2020) Marín Marín, Tamara Alejandra; Zanlungo Matsuhiro, Silvana; Pontificia Universidad Católica de Chile. Facultad de MedicinaNiemann-Pick type A (NPA) disease is a fatal lysosomal neurodegenerative and autosomal recessive disorder. It is characterized by deficiency in acid sphingomyelinase (ASM) and accumulation of sphingomyelin and cholesterol in lysosomes. Unfortunately, there is no cure for patients who die between 2-3 years of age. Previously we described that the c-Abl proapoptotic signaling pathway is key in neuronal death in different neurodegenerative diseases, including lysosomal disorders. Furthermore, recent studies show a role for c-Abl in autophagy and cellular clearance, processes that depend on the lysosome, and are essential for keeping cellular homeostasis. Indeed, autophagy dysfunctions are involved in different pathologies, including neurodegenerative diseases. Considering these antecedents, we propose to evaluate if c-Abl is hyperactivated and modulates autophagy and cellular clearance in NPA disease. The hypothesis of this thesis is that c-Abl hyperactivation blocks the autophagy flux contributing to the neuronal pathogenesis in Niemann Pick type A disease. Our general aim is to determine if c-Abl hyperactivation blocks the autophagy flux contributing to the neuronal pathogenesis in Niemann Pick type A disease. The specific aims are: 1) To determine if the c-Abl signaling pathway is hyperactivated and participates in NPA disease neurodegeneration and 2) To evaluate if hyperactivation of the c-Abl signaling pathway inhibits autophagy flux in NPA models. We used several NPA models including; fibroblasts from NPA patients, Neural Stem Cells derived from these fibroblasts and a NPA mouse. In these models we modulated c-Abl activity and evaluated cell death, cerebellar inflammation and autophagy flux. Our results show that: i) c-Abl is hyperactivated and contributes to the neurodegeneration in in vitro and in vivo NPA models; ii) There are lysosomal and autophagy alterations in NPA models; iii) c-Abl inhibition induces autophagy and decreases lipid accumulation in in vitro NPA models; iv) c-Abl inhibition decreases neuronal death and inflammation at the cerebellum and improves locomotor function in NPA mice and v) the downregulated genes in NPA fibroblasts increase their expression upon Imatinib treatment. Interestingly, these genes are direct or indirectly related with autophagy. These results give new antecedents to understand the role of c-Abl in autophagy regulation and its contribution to the NPA disease pathogenic mechanisms. Additionally, these results allow us to propose c-Abl inhibitors as a therapeutic option for this disease.
- ItemFinding pathogenic commonalities between Niemann-Pick type C and other lysosomal storage disorders: opportunities for shared therapeutic interventions(2020) Yañez Henríquez, María José; Marín Marín, Tamara Alejandra; Balboa Castillo, Elisa; Klein Posternack, Andrés David; Álvarez, Alejandra R.; Zanlungo Matsuhiro, SilvanaLysosomal storage disorders (LSDs) are diseases characterized by the accumulation of macromolecules in the late endocytic system and are caused by inherited defects in genes that encode mainly lysosomal enzymes or transmembrane lysosomal proteins. Niemann-Pick type C disease (NPCD), a LSD characterized by liver damage and progressive neurodegeneration that leads to early death, is caused by mutations in the genes encoding the NPC1 or NPC2 proteins. Both proteins are involved in the transport of cholesterol from the late endosomal compartment to the rest of the cell. Loss of function of these proteins causes primary cholesterol accumulation, and secondary accumulation of other lipids, such as sphingolipids, in lysosomes. Despite years of studying the genetic and molecular bases of NPCD and related-lysosomal disorders, the pathogenic mechanisms involved in these diseases are not fully understood. In this review we will summarize the pathogenic mechanisms described for NPCD and we will discuss their relevance for other LSDs with neurological components such as Niemann- Pick type A and Gaucher diseases. We will particularly focus on the activation of signaling pathways that may be common to these three pathologies with emphasis on how the intra-lysosomal accumulation of lipids leads to pathology, specifically to neurological impairments. We will show that although the primary lipid storage defect is different in these three LSDs, there is a similar secondary accumulation of metabolites and activation of signaling pathways that can lead to common pathogenic mechanisms. This analysis might help to delineate common pathological mechanisms and therapeutic targets for lysosomal storage diseases.
- ItemLysosomal vitamin E accumulation in Niemann-Pick type C disease(2011) Yévenes, Luz Fernanda; Klein Posternack, Andrés David; Castro, Juan Francisco; Marín Marín, Tamara Alejandra; Leal Reyes, Nancy Valeria; Leighton Puga, Federico; Álvarez, Alejandra R.; Zanlungo Matsuhiro, SilvanaNiemann-Pick C disease (NPC) is a neuro-visceral lysosomal storage disorder mainly caused by genetic defects in the NPC1 gene. As a result of loss of NPC1 function large quantities of free cholesterol and other lipids accumulate within late endosomes and lysosomes. In NPC livers and brains, the buildup of lipids correlates with oxidative damage; however the molecular mechanisms that trigger it remain unknown. Here we study potential alterations in vitamin E (α-tocopherol, α-TOH), the most potent endogenous antioxidant, in liver tissue and neurons from NPC1 mice. We found increased levels of α-TOH in NPC cells. We observed accumulation and entrapment of α-TOH in NPC neurons, mainly in the late endocytic pathway. Accordingly, α-TOH levels were increased in cerebellum of NPC1 mice. Also, we found decreased mRNA levels of the α-TOH transporter, α-Tocopherol Transfer Protein (α-TTP), in the cerebellum of NPC1 mice. Finally, by subcellular fractionation studies we detected a significant increase in the hepatic α-TOH content in purified lysosomes from NPC1 mice. In conclusion, these results suggest that NPC cells cannot transport vitamin E correctly leading to α-TOH buildup in the endosomal/lysosomal system. This may result in a decreased bioavailability and impaired antioxidant function of vitamin E in NPC, contributing to the disease pathogenesis.
- ItemProphylactic treatment with the c-Abl inhibitor, neurotinib, diminishes neuronal damage and the convulsive state in pilocarpine-induced mice(Elsevier B.V., 2024) Chandía Cristi, América Valeska; Gutiérrez García, Daniela A.; Dulcey, Andrés E.; Lara, Marcelo; Vargas Rojas, Lina Marcela; Lin, Yi-Han; Jiménez Muñoz, Pablo Salvador; Larenas Barrera, Gabriela Paz; Xu, Xin; Wang, Amy; Owens, Ashley; Dextras, Christopher; Chen, YuChi; Pinto, Claudio; Marín Marín, Tamara Alejandra; Almarza Salazar, Hugo Alcester; Acevedo, Keryma; Cancino Lobos, Gonzalo Ignacio; Hu, Xin; Rojas, Patricio; Ferrer, Marc; Southall, Noel; Henderson, Mark J.; Zanlungo Matsuhiro, Silvana; Marugan, Juan J.; Álvarez Rojas, AlejandraThe molecular mechanisms underlying seizure generation remain elusive, yet they are crucial for developing effective treatments for epilepsy. The current study shows that inhibiting c-Abl tyrosine kinase prevents apoptosis, reduces dendritic spine loss, and maintains N-methyl-D-aspartate (NMDA) receptor subunit 2B (NR2B) phosphorylated in in vitro models of excitotoxicity. Pilocarpine-induced status epilepticus (SE) in mice promotes c-Abl phosphorylation, and disrupting c-Abl activity leads to fewer seizures, increases latency toward SE, and improved animal survival. Currently, clinically used c-Abl inhibitors are non-selective and have poor brain penetration. The allosteric c-Abl inhibitor, neurotinib, used here has favorable potency, selectivity, pharmacokinetics, and vastly improved brain penetration. Neurotinib-administered mice have fewer seizures and improved survival following pilocarpine-SE induction. Our findings reveal c-Abl kinase activation as a key factor in ictogenesis and highlight the impact of its inhibition in preventing the insurgence of epileptic-like seizures in rodents and humans.
- ItemProteomic Analysis of Niemann-Pick Type C Hepatocytes Reveals Potential Therapeutic Targets for Liver Damage(2021) Balboa Castillo, Elisa Ivana; Marín Marín, Tamara Alejandra; Oyarzún Isamitt, Juan Esteban; Contreras, Pablo S.; Hardt, Robert; Van Den Bosch, Thea; Álvarez Rojas, Alejandra; Rebolledo Jaramillo, Boris; Klein, Andres D.; Winter, Dominic; Zanlungo Matsuhiro, 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 NPCD.
- ItemThe c-Abl/p73 pathway induces neurodegeneration in a Parkinson's disease model(2022) Marín Marín, Tamara Alejandra; Valls Jimenez, Cristián Felipe; Jerez C.; Huerta T.; Elgueta D.; Vidal R.L.; Alvaréz Rojas, Alejandra Beatriz; Cancino, GonzaloParkinson's disease is the second most common neurodegenerative disorder. Although it is clear that dopaminergic neurons degenerate, the underlying molecular mechanisms are still unknown, and thus, successful treatment is still elusive. One pro-apoptotic pathway associated with several neurodegenerative diseases is the tyrosine kinase c-Abl and its target p73. Here, we evaluated the contribution of c-Abl and p73 in the degeneration of dopaminergic neurons induced by the neurotoxin 6-hydroxydopamine as a model for Parkinson's disease. First, we found that in SH-SY5Y cells treated with 6-hydroxydopamine, c-Abl and p73 phosphorylation levels were up-regulated. Also, we found that the pro-apoptotic p73 isoform TAp73 was up-regulated. Then, to evaluate whether c-Abl tyrosine kinase activity is necessary for 6-hydroxydopamine-induced apoptosis, we co-treated SH-SY5Y cells with 6-hydroxydopamine and Imatinib, a c-Abl specific inhibitor, observing that Imatinib prevented p73 phosphorylation, TAp73 up-regulation, and protected SH-SY5Y cells treated with 6-hydroxydopamine from apoptosis. Interestingly, this observation was confirmed in the c-Abl conditional null mice, where 6-hydroxydopamine stereotaxic injections induced a lesser reduction of dopaminergic neurons than in the wild-type mice significantly. Finally, we found that the intraperitoneal administration of Imatinib prevented the death of dopaminergic neurons induced by injecting 6-hydroxydopamine stereotaxically in the mice striatum. Thus, our findings support the idea that the c-Abl/p73 pathway is involved in 6-hydroxydopamine degeneration and suggest that inhibition of its kinase activity might be used as a therapeutical drug in Parkinson's disease.