scholarly journals Amyloid-like aggregates cause lysosomal defects in neurons via gain-of-function toxicity

2019 ◽  
Author(s):  
Tillman Schaefer ◽  
Irene Riera-Tur ◽  
Daniel Hornburg ◽  
Archana Mishra ◽  
Lorena Fernández-Mosquera ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Protein Trafficking ◽  
Electron Tomography ◽  
Lysosomal Storage ◽  
Gain Of Function ◽  
Β Protein ◽  
Protein Interactome ◽  
A Subunit

AbstractThe autophagy-lysosomal pathway is impaired in many neurodegenerative diseases characterized by protein aggregation, but the link between aggregation and lysosomal dysfunction remains poorly understood. Here, we use artificial amyloid-like β-sheet proteins (β proteins) to investigate the gain-of-function effects of protein aggregation in primary neurons. We show that β proteins form fibrillar aggregates and cause neurotoxicity. Cryo-electron tomography reveals lysosomal alterations reminiscent of lysosomal storage disorders. Mass spectrometry-based analysis of the β protein interactome shows that β proteins sequester AP-3μ1, a subunit of the AP-3 adaptor complex involved in protein trafficking to lysosomal organelles. Importantly, restoring AP-3μ1 expression ameliorates neurotoxicity caused by β proteins. Our results point to lysosomes as particularly vulnerable organelles in neurodegenerative diseases, and emphasize the role of toxic gain-of-function of protein aggregates in lysosomal defects.

scholarly journals Amyloid-like aggregating proteins cause lysosomal defects in neurons via gain-of-function toxicity

2021 ◽  
Vol 5 (3) ◽  
pp. e202101185
Author(s):  
Irene Riera-Tur ◽  
Tillman Schäfer ◽  
Daniel Hornburg ◽  
Archana Mishra ◽  
Miguel da Silva Padilha ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Protein Trafficking ◽  
Cell Biology ◽  
Electron Tomography ◽  
Lysosomal Storage ◽  
Gain Of Function ◽  
Cryo Electron Tomography ◽  
A Subunit ◽  
Late Stages ◽  
Β Sheet

The autophagy-lysosomal pathway is impaired in many neurodegenerative diseases characterized by protein aggregation, but the link between aggregation and lysosomal dysfunction remains poorly understood. Here, we combine cryo-electron tomography, proteomics, and cell biology studies to investigate the effects of protein aggregates in primary neurons. We use artificial amyloid-like β-sheet proteins (β proteins) to focus on the gain-of-function aspect of aggregation. These proteins form fibrillar aggregates and cause neurotoxicity. We show that late stages of autophagy are impaired by the aggregates, resulting in lysosomal alterations reminiscent of lysosomal storage disorders. Mechanistically, β proteins interact with and sequester AP-3 μ1, a subunit of the AP-3 adaptor complex involved in protein trafficking to lysosomal organelles. This leads to destabilization of the AP-3 complex, missorting of AP-3 cargo, and lysosomal defects. Restoring AP-3μ1 expression ameliorates neurotoxicity caused by β proteins. Altogether, our results highlight the link between protein aggregation, lysosomal impairments, and neurotoxicity.

The Cryo-EM Effect: Structural Biology of Neurodegenerative Disease Proteostasis Factors

2021 ◽  
Author(s):  
Benjamin C Creekmore ◽  
Yi-Wei Chang ◽  
Edward B Lee
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Neurodegenerative Disease ◽  
Electron Tomography ◽  
Ubiquitin Proteasome System ◽  
26S Proteasome ◽  
X Ray Crystallography ◽  
New Information ◽  
A Cell ◽  
Regulate Protein

Abstract Neurodegenerative diseases are characterized by the accumulation of misfolded proteins. This protein aggregation suggests that abnormal proteostasis contributes to aging-related neurodegeneration. A better fundamental understanding of proteins that regulate proteostasis may provide insight into the pathophysiology of neurodegenerative disease and may perhaps reveal novel therapeutic opportunities. The 26S proteasome is the key effector of the ubiquitin-proteasome system responsible for degrading polyubiquitinated proteins. However, additional factors, such as valosin-containing protein (VCP/p97/Cdc48) and C9orf72, play a role in regulation and trafficking of substrates through the normal proteostasis systems of a cell. Nonhuman AAA+ ATPases, such as the disaggregase Hsp104, also provide insights into the biochemical processes that regulate protein aggregation. X-ray crystallography and cryo-electron microscopy (cryo-EM) structures not bound to substrate have provided meaningful information about the 26S proteasome, VCP, and Hsp104. However, recent cryo-EM structures bound to substrate have provided new information about the function and mechanism of these proteostasis factors. Cryo-EM and cryo-electron tomography data combined with biochemical data have also increased the understanding of C9orf72 and its role in maintaining proteostasis. These structural insights provide a foundation for understanding proteostasis mechanisms with near-atomic resolution upon which insights can be gleaned regarding the pathophysiology of neurodegenerative diseases.

scholarly journals Role of Aromatic Side Chains in Amyloid β-Protein Aggregation

2012 ◽  
Vol 3 (12) ◽  
pp. 1008-1016 ◽  
Author(s):  
Risto Cukalevski ◽  
Barry Boland ◽  
Birgitta Frohm ◽  
Eva Thulin ◽  
Dominic Walsh ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Amyloid Β ◽  
Side Chains ◽  
Amyloid Β Protein ◽  
Β Protein ◽  
Aromatic Side Chains

scholarly journals STX2 Promotes Trophoblast Growth, Migration, and Invasion Through Activation of the PI3K-AKT Pathway in Preeclampsia

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan Li ◽  
Xian-li Sun ◽  
Chun-ling Ma ◽  
Chao Li ◽  
Ying Zhan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Migration And Invasion ◽  
Akt Signaling Pathway ◽  
Gain Of Function ◽  
Human Trophoblast ◽  
Pi3k Inhibitor Ly294002 ◽  
Akt Activation ◽  
A Subunit ◽  
Human Trophoblast Cells

ObjectivesAbnormal trophoblast behaviors during pregnancy contribute to the development of preeclampsia (PE). Syntaxin2 (STX2) has been shown to be a crucial epithelial mediator in numerous diseases. However, the functions of STX2 and the mechanisms underlying its role in PE remain largely unknown. The aim of this study was to explore the role of STX2 on trophoblast biology and unravel the molecular mechanisms that contribute to the development and progression of PE.Materials and MethodsWe first compared the expression of STX2 in placental tissues from women with PE and women with normal pregnancies. Then, we investigated the role of STX2 on trophoblast proliferation, migration and invasion in HTR-8/SVneo and primary human trophoblast cells by loss or gain of function experiments. In addition, co-immunoprecipitation, pulldown and immunofluorescence assays were performed to investigate the co-localization of STX2 with other proteins, and to help clarify the mechanisms underlying STX2-mediated functions on trophoblasts.ResultsWe demonstrated that STX2 expression was downregulated in placental tissues of women with PE compared with those from normal pregnancies. Loss and gain of function experiments further confirmed a role for STX2 in cell proliferation, migration and invasion in trophoblasts. By co-immunoprecipitation, pulldown and immunofluorescence co-localization assays, we revealed that STX2 selectively interacted with p85, a subunit of PI3K, and directly recruited p85 to the cytomembrane, thereby activating the AKT signaling pathway. We further demonstrated that the AKT activation was abolished by the use of a PI3K inhibitor (LY294002), which negatively affected STX2-mediated functions on trophoblasts.ConclusionAll together, our findings point to a crucial role for STX2 in PE progression. Our new insights also suggest that STX2 may be a potential diagnostic tool and a novel therapeutic target for treating PE.

scholarly journals Intercellular Spread of Protein Aggregates in Neurodegenerative Disease

2018 ◽  
Vol 34 (1) ◽  
pp. 545-568 ◽  
Author(s):  
Albert A. Davis ◽  
Cheryl E.G. Leyns ◽  
David M. Holtzman
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Neurodegenerative Disease ◽  
Extracellular Space ◽  
Protein Aggregates ◽  
Therapeutic Strategies ◽  
Disease Pathogenesis ◽  
Donor Cells ◽  
Intercellular Spread

Most neurodegenerative diseases are characterized by the accumulation of protein aggregates, some of which are toxic to cells. Mounting evidence demonstrates that in several diseases, protein aggregates can pass from neuron to neuron along connected networks, although the role of this spreading phenomenon in disease pathogenesis is not completely understood. Here we briefly review the molecular and histopathological features of protein aggregation in neurodegenerative disease, we summarize the evidence for release of proteins from donor cells into the extracellular space, and we highlight some other mechanisms by which protein aggregates might be transmitted to recipient cells. We also discuss the evidence that supports a role for spreading of protein aggregates in neurodegenerative disease pathogenesis and some limitations of this model. Finally, we consider potential therapeutic strategies to target spreading of protein aggregates in the treatment of neurodegenerative diseases.

scholarly journals Role of lysosomes in physiological activities, diseases, and therapy

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ziqi Zhang ◽  
Pengfei Yue ◽  
Tianqi Lu ◽  
Yang Wang ◽  
Yuquan Wei ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Growth Regulation ◽  
Malignant Tumors ◽  
Autoimmune Disorders ◽  
Lysosomal Storage Disorders ◽  
Nutrient Sensing ◽  
Inflammasome Activation ◽  
Lysosomal Storage ◽  
Storage Disorders

AbstractLong 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.

scholarly journals Targeted proteolytic products of τ and α-synuclein in neurodegeneration

2021 ◽  
Author(s):  
Yuxing Xia ◽  
Grace M. Lloyd ◽  
Benoit I. Giasson
Keyword(s):  
Cerebrospinal Fluid ◽  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Future Development ◽  
Proteolytic Cleavage ◽  
Therapeutic Interventions ◽  
The Future ◽  
Proteolytic Activities

Abstract CNS pathological inclusions comprising τ or α-synuclein (αSyn) define a spectrum of neurodegenerative diseases, and these can often present concurrently in the same individuals. The aggregation of both proteins is clearly associated with neurodegeneration and the deleterious properties of each protein is further supported by mutations in each gene (MAPT and SNCA, respectively) resulting in disease. The initiating events in most sporadic neurodegenerative diseases are still unclear but growing evidence suggests that the aberrant proteolytic cleavage of τ and αSyn results in products that can be toxic and/or initiate aggregation that can further spread by a prion-like mechanism. The accumulation of some of these cleavage products can further potentiate the progression of protein aggregation transmission and lead to their accumulation in peripheral biofluids such as cerebrospinal fluid (CSF) and blood. The future development of new tools to detect specific τ and αSyn abnormal cleavage products in peripheral biofluids could be useful biomarkers and better understand of the role of unique proteolytic activities could yield therapeutic interventions.

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