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1.
Biochem J ; 479(3): 357-384, 2022 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-35147165

RESUMO

Regulated cell death is a vital and dynamic process in multicellular organisms that maintains tissue homeostasis and eliminates potentially dangerous cells. Apoptosis, one of the better-known forms of regulated cell death, is activated when cell-surface death receptors like Fas are engaged by their ligands (the extrinsic pathway) or when BCL-2-family pro-apoptotic proteins cause the permeabilization of the mitochondrial outer membrane (the intrinsic pathway). Both the intrinsic and extrinsic pathways of apoptosis lead to the activation of a family of proteases, the caspases, which are responsible for the final cell demise in the so-called execution phase of apoptosis. In this review, I will first discuss the most common types of regulated cell death on a morphological basis. I will then consider in detail the molecular pathways of intrinsic and extrinsic apoptosis, discussing how they are activated in response to specific stimuli and are sometimes overlapping. In-depth knowledge of the cellular mechanisms of apoptosis is becoming more and more important not only in the field of cellular and molecular biology but also for its translational potential in several pathologies, including neurodegeneration and cancer.


Assuntos
Proteínas Reguladoras de Apoptose/fisiologia , Apoptose/fisiologia , Animais , Apoptossomas/fisiologia , Apoptossomas/ultraestrutura , Autofagia , Caspases/fisiologia , Humanos , Invertebrados/citologia , Ligantes , Lisossomos/fisiologia , Macrófagos/fisiologia , Membranas Mitocondriais/fisiologia , Necrose , Proteínas de Neoplasias/fisiologia , Permeabilidade , Fagocitose , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Receptores de Morte Celular/fisiologia
2.
Int J Mol Sci ; 23(4)2022 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-35216401

RESUMO

Initially described as lytic bodies due to their degradative and recycling functions, lysosomes play a critical role in metabolic adaptation to nutrient availability. More recently, the contribution of lysosomal proteins to cell signaling has been established, and lysosomes have emerged as signaling hubs that regulate diverse cellular processes, including cell proliferation and cell fate. Deciphering these signaling pathways has revealed an extensive crosstalk between the lysosomal and cell cycle machineries that is only beginning to be understood. Recent studies also indicate that a number of lysosomal proteins are involved in the regulation of embryonic and adult stem cell fate and identity. In this review, we will focus on the role of the lysosome as a signaling platform with an emphasis on its function in integrating nutrient sensing with proliferation and cell cycle progression, as well as in stemness-related features, such as self-renewal and quiescence.


Assuntos
Células-Tronco Adultas/metabolismo , Células-Tronco Adultas/fisiologia , Ciclo Celular/fisiologia , Lisossomos/metabolismo , Lisossomos/fisiologia , Redes e Vias Metabólicas/fisiologia , Animais , Diferenciação Celular/fisiologia , Humanos , Transdução de Sinais/fisiologia
3.
Adv Healthc Mater ; 11(8): e2102185, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35032365

RESUMO

As a process of cellular uptake, endocytosis, with gradient acidity in different endocytic vesicles, is vital for the homeostasis of intracellular nutrients and other functions. To study the dynamics of endocytic pathway, a membrane-anchored pH probe, ECGreen, is synthesized to visualize endocytic vesicles under structured illumination microscopy (SIM), a super-resolution technology. Being sensitive to acidity with increasing fluorescence at low pH, ECGreen can differentiate early and late endosomes as well as endolysosomes. Meanwhile, membrane anchoring not only improves the durability of ECGreen, but also provides an excellent anti-photobleaching property for long-time imaging with SIM. Moreover, by taking these advantages of ECGreen, a multidimensional analysis model containing spatial, temporal, and pH information is successfully developed for elucidating the dynamics of endocytic vesicles and their interactions with mitochondria during autophagy, and reveals a fast conversion of endosomes near the plasma membrane.


Assuntos
Endocitose , Endossomos , Membrana Celular/metabolismo , Endocitose/fisiologia , Endossomos/metabolismo , Endossomos/fisiologia , Fluorescência , Lisossomos/fisiologia
4.
Neurobiol Dis ; 164: 105628, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35033660

RESUMO

Loss of vision due to progressive retinal degeneration is a hallmark of neuronal ceroid lipofuscinoses (NCL), a group of fatal neurodegenerative lysosomal storage diseases. Enzyme substitution therapies represent promising treatment options for NCLs caused by dysfunctions of soluble lysosomal enzymes. Here, we compared the efficacy of a cell-based enzyme substitution strategy and a gene therapy approach to attenuate the retinal pathology in cathepsin D- (CTSD) deficient mice, an animal model of CLN10 disease. Levels of enzymatically active CTSD in mutant retinas were significantly higher after an adeno-associated virus vector-mediated CTSD transfer to retinal glial cells and retinal pigment epithelial cells than after intravitreal transplantations of a CTSD overexpressing clonal neural stem cell line. In line with this finding, the gene therapy treatment restored the disrupted autophagy-lysosomal pathway more effectively than the cell-based approach, as indicated by a complete clearance of storage, significant attenuation of lysosomal hypertrophy, and normalized levels of the autophagy marker sequestosome 1/p62 and microtubule-associated protein 1 light chain 3-II. While the cell-based treatment did not prevent the rapidly progressing loss of various retinal cell types, the gene therapy approach markedly attenuated retinal degeneration as demonstrated by a pronounced rescue of photoreceptor cells and rod bipolar cells.


Assuntos
Autofagia/fisiologia , Catepsina D/genética , Terapia Genética , Lisossomos/fisiologia , Degeneração Retiniana/terapia , Animais , Catepsina D/metabolismo , Modelos Animais de Doenças , Camundongos , Camundongos Knockout , Degeneração Retiniana/genética
5.
Commun Biol ; 5(1): 5, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013510

RESUMO

Lysosome axonal transport is important for the clearance of cargoes sequestered by the endocytic and autophagic pathways. Building on observations that mutations in the JIP3 (MAPK8IP3) gene result in lysosome-filled axonal swellings, we analyzed the impact of JIP3 depletion on the cytoskeleton of human neurons. Dynamic focal lysosome accumulations were accompanied by disruption of the axonal periodic scaffold (spectrin, F-actin and myosin II) throughout each affected axon. Additionally, axonal microtubule organization was locally disrupted at each lysosome-filled swelling. This local axonal microtubule disorganization was accompanied by accumulations of both F-actin and myosin II. These results indicate that transport of axonal lysosomes is functionally interconnected with mechanisms that control the organization and maintenance of the axonal cytoskeleton. They have potential relevance to human neurological disease arising from JIP3 mutations as well as for neurodegenerative diseases associated with the focal accumulations of lysosomes within axonal swellings such as Alzheimer's disease.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Transporte Axonal , Axônios/fisiologia , Citoesqueleto/fisiologia , Lisossomos/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Transporte Biológico , Humanos , Proteínas do Tecido Nervoso/metabolismo
6.
STAR Protoc ; 2(4): 100916, 2021 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-34755119

RESUMO

The lysosomal compartment is a key hub for cell metabolism, and morphological alterations have been described in several pathological conditions. Here, we describe the use of amino acid analogs modified by the presence of a methyl ester group that accumulates within lysosomes. This generates an intraluminal osmotic effect able to trigger a rapid and selective expansion of the lysosomal compartment within 2 h of treatment. We also present protocols to preserve lysosomal morphology, which yields a more accurate size measurement. For complete details on the use and execution of this protocol, please refer to Scerra et al. (2021).


Assuntos
Aminoácidos , Histocitoquímica/métodos , Lisossomos , Aminoácidos/química , Aminoácidos/metabolismo , Técnicas de Cultura de Células , Células Cultivadas , Ésteres/química , Ésteres/metabolismo , Células HeLa , Humanos , Lisossomos/química , Lisossomos/metabolismo , Lisossomos/fisiologia , Microscopia Confocal
7.
J Biomed Sci ; 28(1): 72, 2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34706729

RESUMO

BACKGROUND: During autophagy defense against invading microbes, certain lipid types are indispensable for generating specialized membrane-bound organelles. The lipid composition of autophagosomes remains obscure, as does the issue of how specific lipids and lipid-associated enzymes participate in autophagosome formation and maturation. Helicobacter pylori is auxotrophic for cholesterol and converts cholesterol to cholesteryl glucoside derivatives, including cholesteryl 6'-O-acyl-α-D-glucoside (CAG). We investigated how CAG and its biosynthetic acyltransferase assist H. pylori to escape host-cell autophagy. METHODS: We applied a metabolite-tagging method to obtain fluorophore-containing cholesteryl glucosides that were utilized to understand their intracellular locations. H. pylori 26695 and a cholesteryl glucosyltransferase (CGT)-deletion mutant (ΔCGT) were used as the standard strain and the negative control that contains no cholesterol-derived metabolites, respectively. Bacterial internalization and several autophagy-related assays were conducted to unravel the possible mechanism that H. pylori develops to hijack the host-cell autophagy response. Subcellular fractions of H. pylori-infected AGS cells were obtained and measured for the acyltransferase activity. RESULTS: The imaging studies of fluorophore-labeled cholesteryl glucosides pinpointed their intracellular localization in AGS cells. The result indicated that CAG enhances the internalization of H. pylori in AGS cells. Particularly, CAG, instead of CG and CPG, is able to augment the autophagy response induced by H. pylori. How CAG participates in the autophagy process is multifaceted. CAG was found to intervene in the degradation of autophagosomes and reduce lysosomal biogenesis, supporting the idea that intracellular H. pylori is harbored by autophago-lysosomes in favor of the bacterial survival. Furthermore, we performed the enzyme activity assay of subcellular fractions of H. pylori-infected AGS cells. The analysis showed that the acyltransferase is mainly distributed in autophago-lysosomal compartments. CONCLUSIONS: Our results support the idea that the acyltransferase is mainly distributed in the subcellular compartment consisting of autophagosomes, late endosomes, and lysosomes, in which the acidic environment is beneficial for the maximal acyltransferase activity. The resulting elevated level of CAG can facilitate bacterial internalization, interfere with the autophagy flux, and causes reduced lysosomal biogenesis.


Assuntos
Aciltransferases/metabolismo , Colesterol/análogos & derivados , Infecções por Helicobacter/fisiopatologia , Helicobacter pylori/fisiologia , Lisossomos/fisiologia , Animais , Colesterol/biossíntese , Infecções por Helicobacter/enzimologia , Infecções por Helicobacter/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Organismos Livres de Patógenos Específicos
8.
Dev Cell ; 56(23): 3250-3263.e5, 2021 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-34706264

RESUMO

Viral entry and egress are important determinants of virus infectivity and pathogenicity. ß-coronaviruses, including the COVID-19 virus SARS-CoV-2 and mouse hepatitis virus (MHV), exploit the lysosomal exocytosis pathway for egress. Here, we show that SARS-CoV-2 ORF3a, but not SARS-CoV ORF3a, promotes lysosomal exocytosis. SARS-CoV-2 ORF3a facilitates lysosomal targeting of the BORC-ARL8b complex, which mediates trafficking of lysosomes to the vicinity of the plasma membrane, and exocytosis-related SNARE proteins. The Ca2+ channel TRPML3 is required for SARS-CoV-2 ORF3a-mediated lysosomal exocytosis. Expression of SARS-CoV-2 ORF3a greatly elevates extracellular viral release in cells infected with the coronavirus MHV-A59, which itself lacks ORF3a. In SARS-CoV-2 ORF3a, Ser171 and Trp193 are critical for promoting lysosomal exocytosis and blocking autophagy. When these residues are introduced into SARS-CoV ORF3a, it acquires the ability to promote lysosomal exocytosis and inhibit autophagy. Our results reveal a mechanism by which SARS-CoV-2 interacts with host factors to promote its extracellular egress.


Assuntos
Fatores de Ribosilação do ADP/metabolismo , Autofagia , Exocitose , Lisossomos/fisiologia , Canais de Potencial de Receptor Transitório/metabolismo , Proteínas Viroporinas/metabolismo , Liberação de Vírus , Fatores de Ribosilação do ADP/genética , Animais , COVID-19/virologia , Células HeLa , Humanos , Camundongos , SARS-CoV-2/isolamento & purificação , Canais de Potencial de Receptor Transitório/genética , Proteínas Viroporinas/genética
9.
Hepatol Commun ; 5(12): 2121-2138, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34558854

RESUMO

Lysosomes are intracellular acidic organelles with catabolic functions that contribute to the activation of autophagy. Although autophagy abnormality is associated with defects in lysosomal acidification during the progression of nonalcoholic fatty liver disease (NAFLD), the mechanisms of control of lysosomal acidification are not well understood at the molecular level. Thus, we aimed to elucidate the role of the orphan nuclear receptor retinoic acid-related orphan receptor α (RORα) in lysosomal acidification and autophagic flux, particularly in nutrition-enriched hepatocytes. First, lysosomal acidity was much lower in the hepatocytes obtained from hepatocyte-specific RORα-deleted (RORα-LKO) mice, whereas the infusion of an adenovirus encoding RORα in wild-type hepatocytes increased lysosomal acidity, as determined by LysoSensor. Second, the lysosomal translocation of the mechanistic target of rapamycin was increased and immature cathepsin D was accumulated in the liver of RORα-LKO mice. Third, the accumulation of LC3-II, p62/sequestosome 1 (SQSTM1), and neighbor of BRCA1 gene 1 (NBR1) was increased in the livers of RORα-LKO mice, indicating an impaired autophagic flux in the livers. Consistently, the number of autolysosomes containing mitochondria and lipid droplets was dramatically reduced in the RORα-deleted hepatocytes. Finally, we found that RORα induced the transcription of genes involved in lysosomal function, such as Atp6v1g1, a vacuolar H+ -ATPase (v-ATPase) subunit, which were largely down-regulated in the livers of mice with high-fat diet-induced NAFLD and patients with hepatitis. Conclusion: Targeting RORα may be a potential therapeutic strategy to restore lysosomal acidification, which inhibits the progression of NAFLD.


Assuntos
Acidose/genética , Autofagia/genética , Lisossomos/fisiologia , Hepatopatia Gordurosa não Alcoólica/genética , Membro 1 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Animais , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Hepatócitos/metabolismo , Concentração de Íons de Hidrogênio , Fígado/metabolismo , Camundongos , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/etiologia
10.
Cells ; 10(9)2021 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-34572128

RESUMO

Chronic exercise is widely recognized as an important contributor to healthspan in humans and in diverse animal models. Recently, we have demonstrated that Sestrins, a family of evolutionarily conserved exercise-inducible proteins, are critical mediators of exercise benefits in flies and mice. Knockout of Sestrins prevents exercise adaptations to endurance and flight in Drosophila, and similarly prevents benefits to endurance and metabolism in exercising mice. In contrast, overexpression of dSestrin in muscle mimics several of the molecular and physiological adaptations characteristic of endurance exercise. Here, we extend those observations to examine the impact of dSestrin on preserving speed and increasing lysosomal activity. We find that dSestrin is a critical factor driving exercise adaptations to climbing speed, but is not absolutely required for exercise to increase lysosomal activity in Drosophila. The role of Sestrin in increasing speed during chronic exercise requires both the TORC2/AKT axis and the PGC1α homolog spargel, while dSestrin requires interactions with TORC1 to cell-autonomously increase lysosomal activity. These results highlight the conserved role of Sestrins as key factors that drive diverse physiological adaptations conferred by chronic exercise.


Assuntos
Adaptação Fisiológica , Proteínas de Drosophila/metabolismo , Locomoção , Lisossomos/fisiologia , Oxirredutases/metabolismo , Condicionamento Físico Animal , Fator B de Elongação Transcricional Positiva/metabolismo , Animais , Fenômenos Biomecânicos , Drosophila , Proteínas de Drosophila/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Oxirredutases/genética , Fator B de Elongação Transcricional Positiva/genética , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo
12.
Neurosci Lett ; 762: 136155, 2021 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-34358625

RESUMO

Lysosomal storage diseases were recognized and defined over a century ago as a class of disorders affecting mostly children and causing systemic disease often accompanied by major neurological consequences. Since their discovery, research focused on understanding their causes has been an important driver of our ever-expanding knowledge of cell biology and the central role that lysosomes play in cell function. Today we recognize over 50 so-called storage diseases, with most understood at the level of gene, protein and pathway involvement, but few fully clarified in terms of how the defective lysosomal function causes brain disease; even fewer have therapies that can effectively rescue brain function. Importantly, we also recognize that storage diseases are not simply a class of lysosomal disorders all by themselves, as increasingly a critical role for the greater lysosomal system with its endosomal, autophagosomal and salvage streams has also emerged in a host of neurodevelopmental and neurodegenerative diseases. Despite persistent challenges across all aspects of these complex disorders, and as reflected in this and other articles focused on lysosomal storage diseases in this special issue of Neuroscience Letters, the progress and promise to both understand and effectively treat these conditions has never been greater.


Assuntos
Doenças por Armazenamento dos Lisossomos/fisiopatologia , Lisossomos/fisiologia , Animais , Humanos
13.
Am J Physiol Endocrinol Metab ; 321(3): E410-E416, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34338043

RESUMO

Type 1 diabetes is an insulin-dependent, autoimmune disease where the pancreatic ß cells are destroyed resulting in hyperglycemia. This multifactorial disease involves multiple environmental and genetic factors, and has no clear etiology. Accumulating evidence suggests that early signaling defects within the ß cells may promote a change in the local immune milieu leading to autoimmunity. Therefore, many studies have been focused on intrinsic ß-cell mechanisms that aid in the restoration of cellular homeostasis under environmental conditions that cause dysfunction. One of these intrinsic mechanisms to promote homeostasis is autophagy, defects which are clearly linked with ß-cell dysfunction in the context of type 2 diabetes. Recent studies have now also pointed towards ß-cell autophagy defects in the context of type 1 diabetes. In this perspectives review, we will discuss the evidence supporting a role for ß-cell autophagy in the pathogenesis of type 1 diabetes, including a potential role for unconventional secretion of autophagosomes/lysosomes in the changing dialogue between the ß cell and immune cells.


Assuntos
Autofagia , Diabetes Mellitus Tipo 1/fisiopatologia , Células Secretoras de Insulina/fisiologia , Animais , Humanos , Lisossomos/fisiologia
14.
Glycoconj J ; 38(5): 625-647, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34390447

RESUMO

Glycans have been shown to function as versatile molecular signals in cells. This prompted us to look at their roles in endocytosis, endolysosomal system and autophagy. We start by introducing the cell biological aspects of these pathways, the concept of the sugar code, and provide an overview on the role of glycans in the targeting of lysosomal proteins and in lysosomal functions. Moreover, we review evidence on the regulation of endocytosis and autophagy by glycans. Finally, we discuss the emerging concept that cytosolic exposure of luminal glycans, and their detection by endogenous lectins, provides a mechanism for the surveillance of the integrity of the endolysosomal compartments, and serves their eventual repair or disposal.


Assuntos
Autofagia/fisiologia , Endocitose/fisiologia , Lisossomos/fisiologia , Polissacarídeos/metabolismo , Regulação da Expressão Gênica , Proteínas/genética , Proteínas/metabolismo
16.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360836

RESUMO

Lysyl oxidase-like 3 (LOXL3), belonging to the lysyl oxidase family, is responsible for the crosslinking in collagen or elastin. The cellular localization of LOXL3 is in the extracellular space by reason of its canonical function. In tumors, the presence of LOXL3 has been associated with genomic stability, cell proliferation, and metastasis. In silico analysis has shown that glioblastoma was among tumors with the highest LOXL3 expression levels. LOXL3 silencing of U87MG cells by siRNA led to the spreading of the tumor cell surface, and the transcriptome analysis of these cells revealed an upregulation of genes coding for extracellular matrix, cell adhesion, and cytoskeleton components, convergent to an increase in cell adhesion and a decrease in cell invasion observed in functional assays. Significant correlations of LOXL3 expression with genes coding for tubulins were observed in the mesenchymal subtype in the TCGA RNA-seq dataset of glioblastoma (GBM). Conversely, genes involved in endocytosis and lysosome formation, along with MAPK-binding proteins related to focal adhesion turnover, were downregulated, which may corroborate the observed decrease in cell viability and increase in the rate of cell death. Invasiveness is a major determinant of the recurrence and poor outcome of GBM patients, and downregulation of LOXL3 may contribute to halting the tumor cell invasion.


Assuntos
Aminoácido Oxirredutases/metabolismo , Adesão Celular , Regulação Neoplásica da Expressão Gênica , Glioblastoma/enzimologia , Aminoácido Oxirredutases/genética , Aminoácido Oxirredutases/fisiologia , Linhagem Celular Tumoral , Proliferação de Células , Simulação por Computador , Citoesqueleto/metabolismo , Endocitose , Matriz Extracelular/metabolismo , Perfilação da Expressão Gênica , Glioblastoma/genética , Glioblastoma/patologia , Glioblastoma/fisiopatologia , Humanos , Lisossomos/fisiologia , Invasividade Neoplásica
17.
J Invest Dermatol ; 141(12): 2838-2848.e4, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34090855

RESUMO

Atopic dermatitis and psoriasis are frequent chronic inflammatory skin diseases. Autophagy plays a substantial role in the homeostasis of an organism. Loss or impairment of autophagy is associated with multiple diseases. To investigate the possibility that autophagy plays a role in atopic dermatitis and psoriasis, we investigated the levels of key ATG proteins in human skin specimens as well as in primary human epidermal keratinocytes exposed to inflammatory stimuli in vitro. Although TNF-α facilitated the induction of autophagy in an initial phase, it reduced the levels and enzymatic activities of lysosomal cathepsins in later time periods, resulting in autophagy inhibition. Therefore, TNF-α appears to play a dual role in the regulation of autophagy. The relevance of these in vitro findings was supported by the observation that the protein levels of cathepsins D and L are decreased in both psoriasis and atopic dermatitis skin specimens. Taken together, this study suggests that TNF-α blocks autophagy in keratinocytes after long-term exposure, a mechanism that may contribute to the chronicity of inflammatory diseases of the skin and, perhaps, of other organs.


Assuntos
Autofagia/fisiologia , Dermatite Atópica/etiologia , Queratinócitos/fisiologia , Lisossomos/fisiologia , Psoríase/etiologia , Autofagia/efeitos dos fármacos , Proteína 5 Relacionada à Autofagia/análise , Células Cultivadas , Humanos , Queratinócitos/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , Proteínas Associadas aos Microtúbulos/análise , Fator de Necrose Tumoral alfa/farmacologia
18.
Autophagy ; 17(8): 2040-2042, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34110247

RESUMO

Different types of autophagy co-exist in all mammalian cells, however, the specific contribution of each of these autophagic pathways to the maintenance of cellular proteostasis and cellular function remains unknown. In this work, we have investigated the consequences of failure of chaperone-mediated autophagy (CMA) in neurons and compared the impact, on the neuronal proteome, of CMA loss to that of macroautophagy loss. We found that these autophagic pathways are non-redundant and that CMA is the main one responsible for maintenance of the metastable proteome (the one at risk of aggregation). We demonstrate that loss of CMA, as the one that occurs in aging, has a synergistic effect with the proteotoxicity associated with neurodegenerative conditions such as Alzheimer disease (AD) and, conversely, that, pharmacological enhancement of CMA is effective in improving both behavior and pathology in two different AD mouse models.


Assuntos
Autofagia/fisiologia , Autofagia Mediada por Chaperonas/fisiologia , Lisossomos/fisiologia , Proteostase/fisiologia , Envelhecimento/metabolismo , Animais , Humanos , Lisossomos/metabolismo , Neurônios/metabolismo
19.
J Hematol Oncol ; 14(1): 79, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33990205

RESUMO

Long known as digestive organelles, lysosomes have now emerged as multifaceted centers responsible for degradation, nutrient sensing, and immunity. Growing evidence also implicates role of lysosome-related mechanisms in pathologic process. In this review, we discuss physiological function of lysosomes and, more importantly, how the homeostasis of lysosomes is disrupted in several diseases, including atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, lysosomal storage disorders, and malignant tumors. In atherosclerosis and Gaucher disease, dysfunction of lysosomes changes cytokine secretion from macrophages, partially through inflammasome activation. In neurodegenerative diseases, defect autophagy facilitates accumulation of toxic protein and dysfunctional organelles leading to neuron death. Lysosomal dysfunction has been demonstrated in pathology of pancreatitis. Abnormal autophagy activation or inhibition has been revealed in autoimmune disorders. In tumor microenvironment, malignant phenotypes, including tumorigenesis, growth regulation, invasion, drug resistance, and radiotherapy resistance, of tumor cells and behaviors of tumor-associated macrophages, fibroblasts, dendritic cells, and T cells are also mediated by lysosomes. Based on these findings, a series of therapeutic methods targeting lysosomal proteins and processes have been developed from bench to bedside. In a word, present researches corroborate lysosomes to be pivotal organelles for understanding pathology of atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, and lysosomal storage disorders, and malignant tumors and developing novel therapeutic strategies.


Assuntos
Aterosclerose/metabolismo , Lisossomos/fisiologia , Humanos
20.
Sci Rep ; 11(1): 10249, 2021 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-33986446

RESUMO

We have previously shown that the DBA/2J versus AKR/J mouse strain is associated with decreased autophagy-mediated lysosomal hydrolysis of cholesterol esters. Our objective was to determine differences in lysosome function in AKR/J and DBA/2J macrophages, and identify the responsible genes. Using a novel dual-labeled indicator of lysosome function, DBA/2J versus AKR/J bone marrow derived macrophages had significantly decreased lysosome function. We performed quantitative trait loci mapping of lysosome function in bone marrow macrophages from an AKR/J × DBA/2J strain intercross. Four distinct lysosome function loci were identified, which we named macrophage lysosome function modifier (Mlfm) Mlfm1 through Mlfm4. The strongest locus Mlfm1 harbors the Gpnmb gene, which has been shown to recruit autophagy protein light chain 3 to autophagosomes for lysosome fusion. The parental DBA/2J strain has a nonsense variant in Gpnmb. siRNA knockdown of Gpnmb in AKR/J macrophages decreased lysosome function, and Gpnmb deletion through CRISP/Cas9 editing in RAW 264.7 mouse macrophages also demonstrated a similar result. Furthermore, a DBA/2 substrain, called DBA/2J-Gpnmb+/SjJ, contains the wildtype Gpnmb gene, and macrophages from this Gpnmb-preserved DBA/2 substrain exhibited recovered lysosome function. In conclusion, we identified Gpnmb as a causal modifier gene of lysosome function in this strain pair.


Assuntos
Proteínas do Olho/genética , Lisossomos/metabolismo , Macrófagos/fisiologia , Glicoproteínas de Membrana/genética , Animais , Mapeamento Cromossômico/métodos , Proteínas do Olho/metabolismo , Feminino , Genes Modificadores/genética , Lisossomos/genética , Lisossomos/fisiologia , Macrófagos/metabolismo , Masculino , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos AKR , Camundongos Endogâmicos DBA , Locos de Características Quantitativas/genética
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