101
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Abstract
Proteases comprise a variety of enzymes defined by their ability to catalytically hydrolyze the peptide bonds of other proteins, resulting in protein lysis. Cathepsins, specifically, encompass a class of at least twenty proteases with potent endopeptidase activity. They are located subcellularly in lysosomes, organelles responsible for the cell’s degradative and autophagic processes, and are vital for normal lysosomal function. Although cathepsins are involved in a multitude of cell signaling activities, this chapter will focus on the role of cathepsins (with a special emphasis on Cathepsin B) in neuronal plasticity. We will broadly define what is known about regulation of cathepsins in the central nervous system and compare this with their dysregulation after injury or disease. Importantly, we will delineate what is currently known about the role of cathepsins in axon regeneration and plasticity after spinal cord injury. It is well established that normal cathepsin activity is integral to the function of lysosomes. Without normal lysosomal function, autophagy and other homeostatic cellular processes become dysregulated resulting in axon dystrophy. Furthermore, controlled activation of cathepsins at specialized neuronal structures such as axonal growth cones and dendritic spines have been positively implicated in their plasticity. This chapter will end with a perspective on the consequences of cathepsin dysregulation versus controlled, localized regulation to clarify how cathepsins can contribute to both neuronal plasticity and neurodegeneration.
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Affiliation(s)
- Amanda Phuong Tran
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
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102
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Zhao YG, Codogno P, Zhang H. Machinery, regulation and pathophysiological implications of autophagosome maturation. Nat Rev Mol Cell Biol 2021; 22:733-750. [PMID: 34302147 PMCID: PMC8300085 DOI: 10.1038/s41580-021-00392-4] [Citation(s) in RCA: 213] [Impact Index Per Article: 71.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2021] [Indexed: 02/07/2023]
Abstract
Autophagy is a versatile degradation system for maintaining cellular homeostasis whereby cytosolic materials are sequestered in a double-membrane autophagosome and subsequently delivered to lysosomes, where they are broken down. In multicellular organisms, newly formed autophagosomes undergo a process called 'maturation', in which they fuse with vesicles originating from endolysosomal compartments, including early/late endosomes and lysosomes, to form amphisomes, which eventually become degradative autolysosomes. This fusion process requires the concerted actions of multiple regulators of membrane dynamics, including SNAREs, tethering proteins and RAB GTPases, and also transport of autophagosomes and late endosomes/lysosomes towards each other. Multiple mechanisms modulate autophagosome maturation, including post-translational modification of key components, spatial distribution of phosphoinositide lipid species on membranes, RAB protein dynamics, and biogenesis and function of lysosomes. Nutrient status and various stresses integrate into the autophagosome maturation machinery to coordinate the progression of autophagic flux. Impaired autophagosome maturation is linked to the pathogenesis of various human diseases, including neurodegenerative disorders, cancer and myopathies. Furthermore, invading pathogens exploit various strategies to block autophagosome maturation, thus evading destruction and even subverting autophagic vacuoles (autophagosomes, amphisomes and autolysosomes) for survival, growth and/or release. Here, we discuss the recent progress in our understanding of the machinery and regulation of autophagosome maturation, the relevance of these mechanisms to human pathophysiology and how they are harnessed by pathogens for their benefit. We also provide perspectives on targeting autophagosome maturation therapeutically.
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Affiliation(s)
- Yan G. Zhao
- grid.263817.90000 0004 1773 1790Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, People’s Republic of China
| | - Patrice Codogno
- grid.508487.60000 0004 7885 7602Institut Necker-Enfants Malades, INSERM U1151-CNRS UMR 8253, Université de Paris, Paris, France
| | - Hong Zhang
- grid.9227.e0000000119573309National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, People’s Republic of China ,grid.410726.60000 0004 1797 8419College of Life Sciences, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
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103
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Abstract
In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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104
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Andres-Alonso M, Kreutz MR, Karpova A. Autophagy and the endolysosomal system in presynaptic function. Cell Mol Life Sci 2020; 78:2621-2639. [PMID: 33340068 PMCID: PMC8004491 DOI: 10.1007/s00018-020-03722-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/17/2020] [Accepted: 11/24/2020] [Indexed: 12/11/2022]
Abstract
The complex morphology of neurons, the specific requirements of synaptic neurotransmission and the accompanying metabolic demands create a unique challenge for proteostasis. The main machineries for neuronal protein synthesis and degradation are localized in the soma, while synaptic junctions are found at vast distances from the cell body. Sophisticated mechanisms must, therefore, ensure efficient delivery of newly synthesized proteins and removal of faulty proteins. These requirements are exacerbated at presynaptic sites, where the demands for protein turnover are especially high due to synaptic vesicle release and recycling that induces protein damage in an intricate molecular machinery, and where replacement of material is hampered by the extreme length of the axon. In this review, we will discuss the contribution of the two major pathways in place, autophagy and the endolysosomal system, to presynaptic protein turnover and presynaptic function. Although clearly different in their biogenesis, both pathways are characterized by cargo collection and transport into distinct membrane-bound organelles that eventually fuse with lysosomes for cargo degradation. We summarize the available evidence with regard to their degradative function, their regulation by presynaptic machinery and the cargo for each pathway. Finally, we will discuss the interplay of both pathways in neurons and very recent findings that suggest non-canonical functions of degradative organelles in synaptic signalling and plasticity.
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Affiliation(s)
- Maria Andres-Alonso
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany
- Leibniz Group 'Dendritic Organelles and Synaptic Function', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Michael R Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
- Leibniz Group 'Dendritic Organelles and Synaptic Function', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
- Center for Behavioral Brain Sciences, Otto Von Guericke University, Magdeburg, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
| | - Anna Karpova
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
- Center for Behavioral Brain Sciences, Otto Von Guericke University, Magdeburg, Germany.
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105
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Li Z, Ding G, Wang Y, Zheng Z, Lv J. Safety profile of the transcription factor EB (TFEB)-based gene therapy through intracranial injection in mice. Transl Neurosci 2020; 11:241-250. [PMID: 33335764 PMCID: PMC7711953 DOI: 10.1515/tnsci-2020-0132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 02/06/2023] Open
Abstract
Transcription factor EB (TFEB)-based gene therapy is a promising therapeutic strategy in treating neurodegenerative diseases by promoting autophagy/lysosome-mediated degradation and clearance of misfolded proteins that contribute to the pathogenesis of these diseases. However, recent findings have shown that TFEB has proinflammatory properties, raising the safety concerns about its clinical application. To investigate whether TFEB induces significant inflammatory responses in the brain, male C57BL/6 mice were injected with phosphate-buffered saline (PBS), adeno-associated virus serotype 8 (AAV8) vectors overexpressing mouse TFEB (pAAV8-CMV-mTFEB), or AAV8 vectors expressing green fluorescent proteins (GFPs) in the barrel cortex. The brain tissue samples were collected at 2 months after injection. Western blotting and immunofluorescence staining showed that mTFEB protein levels were significantly increased in the brain tissue samples of mice injected with mTFEB-overexpressing vectors compared with those injected with PBS or GFP-overexpressing vectors. pAAV8-CMV-mTFEB injection resulted in significant elevations in the mRNA and protein levels of lysosomal biogenesis indicators in the brain tissue samples. No significant changes were observed in the expressions of GFAP, Iba1, and proinflammation mediators in the pAAV8-CMV-mTFEB-injected brain compared with those in the control groups. Collectively, our results suggest that AAV8 successfully mediates mTFEB overexpression in the mouse brain without inducing apparent local inflammation, supporting the safety of TFEB-based gene therapy in treating neurodegenerative diseases.
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Affiliation(s)
- Zhenyu Li
- Department of Neurosurgery, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, China
| | - Guangqian Ding
- Department of Neurosurgery, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, China
| | - Yudi Wang
- Department of Neurosurgery, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, China
| | - Zelong Zheng
- Department of Neurosurgery, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, China
| | - Jianping Lv
- Department of Neurosurgery, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, China
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106
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Giovedì S, Ravanelli MM, Parisi B, Bettegazzi B, Guarnieri FC. Dysfunctional Autophagy and Endolysosomal System in Neurodegenerative Diseases: Relevance and Therapeutic Options. Front Cell Neurosci 2020; 14:602116. [PMID: 33390907 PMCID: PMC7773602 DOI: 10.3389/fncel.2020.602116] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 11/11/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagy and endolysosomal trafficking are crucial in neuronal development, function and survival. These processes ensure efficient removal of misfolded aggregation-prone proteins and damaged organelles, such as dysfunctional mitochondria, thus allowing the maintenance of proper cellular homeostasis. Beside this, emerging evidence has pointed to their involvement in the regulation of the synaptic proteome needed to guarantee an efficient neurotransmitter release and synaptic plasticity. Along this line, an intimate interplay between the molecular machinery regulating synaptic vesicle endocytosis and synaptic autophagy is emerging, suggesting that synaptic quality control mechanisms need to be tightly coupled to neurosecretion to secure release accuracy. Defects in autophagy and endolysosomal pathway have been associated with neuronal dysfunction and extensively reported in Alzheimer's, Parkinson's, Huntington's and amyotrophic lateral sclerosis among other neurodegenerative diseases, with common features and emerging genetic bases. In this review, we focus on the multiple roles of autophagy and endolysosomal system in neuronal homeostasis and highlight how their defects probably contribute to synaptic default and neurodegeneration in the above-mentioned diseases, discussing the most recent options explored for therapeutic interventions.
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Affiliation(s)
- Silvia Giovedì
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Margherita Maria Ravanelli
- Vita-Salute San Raffaele University, Milan, Italy.,Division of Neuroscience, Neuropsychopharmacology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Barbara Parisi
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Barbara Bettegazzi
- Vita-Salute San Raffaele University, Milan, Italy.,Division of Neuroscience, Gene Therapy of Neurodegenerative Diseases Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Fabrizia Claudia Guarnieri
- Vita-Salute San Raffaele University, Milan, Italy.,Division of Neuroscience, Neuropsychopharmacology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Institute of Neuroscience, National Research Council (CNR), Milan, Italy
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107
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Ca 2+ Dyshomeostasis Disrupts Neuronal and Synaptic Function in Alzheimer's Disease. Cells 2020; 9:cells9122655. [PMID: 33321866 PMCID: PMC7763805 DOI: 10.3390/cells9122655] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023] Open
Abstract
Ca2+ homeostasis is essential for multiple neuronal functions and thus, Ca2+ dyshomeostasis can lead to widespread impairment of cellular and synaptic signaling, subsequently contributing to dementia and Alzheimer's disease (AD). While numerous studies implicate Ca2+ mishandling in AD, the cellular basis for loss of cognitive function remains under investigation. The process of synaptic degradation and degeneration in AD is slow, and constitutes a series of maladaptive processes each contributing to a further destabilization of the Ca2+ homeostatic machinery. Ca2+ homeostasis involves precise maintenance of cytosolic Ca2+ levels, despite extracellular influx via multiple synaptic Ca2+ channels, and intracellular release via organelles such as the endoplasmic reticulum (ER) via ryanodine receptor (RyRs) and IP3R, lysosomes via transient receptor potential mucolipin channel (TRPML) and two pore channel (TPC), and mitochondria via the permeability transition pore (PTP). Furthermore, functioning of these organelles relies upon regulated inter-organelle Ca2+ handling, with aberrant signaling resulting in synaptic dysfunction, protein mishandling, oxidative stress and defective bioenergetics, among other consequences consistent with AD. With few effective treatments currently available to mitigate AD, the past few years have seen a significant increase in the study of synaptic and cellular mechanisms as drivers of AD, including Ca2+ dyshomeostasis. Here, we detail some key findings and discuss implications for future AD treatments.
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108
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Marshall KE, Vadukul DM, Staras K, Serpell LC. Misfolded amyloid-β-42 impairs the endosomal-lysosomal pathway. Cell Mol Life Sci 2020; 77:5031-5043. [PMID: 32025743 PMCID: PMC7658065 DOI: 10.1007/s00018-020-03464-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 12/29/2022]
Abstract
Misfolding and aggregation of proteins is strongly linked to several neurodegenerative diseases, but how such species bring about their cytotoxic actions remains poorly understood. Here we used specifically-designed optical reporter probes and live fluorescence imaging in primary hippocampal neurons to characterise the mechanism by which prefibrillar, oligomeric forms of the Alzheimer's-associated peptide, Aβ42, exert their detrimental effects. We used a pH-sensitive reporter, Aβ42-CypHer, to track Aβ internalisation in real-time, demonstrating that oligomers are rapidly taken up into cells in a dynamin-dependent manner, and trafficked via the endo-lysosomal pathway resulting in accumulation in lysosomes. In contrast, a non-assembling variant of Aβ42 (vAβ42) assayed in the same way is not internalised. Tracking ovalbumin uptake into cells using CypHer or Alexa Fluor tags shows that preincubation with Aβ42 disrupts protein uptake. Our results identify a potential mechanism by which amyloidogenic aggregates impair cellular function through disruption of the endosomal-lysosomal pathway.
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Affiliation(s)
- Karen E Marshall
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK
| | - Devkee M Vadukul
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK
| | - Kevin Staras
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK.
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, BN1 9QG, UK.
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109
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Autophagy and Redox Homeostasis in Parkinson's: A Crucial Balancing Act. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:8865611. [PMID: 33224433 PMCID: PMC7671810 DOI: 10.1155/2020/8865611] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/23/2020] [Accepted: 10/14/2020] [Indexed: 12/13/2022]
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated primarily from endogenous biochemical reactions in mitochondria, endoplasmic reticulum (ER), and peroxisomes. Typically, ROS/RNS correlate with oxidative damage and cell death; however, free radicals are also crucial for normal cellular functions, including supporting neuronal homeostasis. ROS/RNS levels influence and are influenced by antioxidant systems, including the catabolic autophagy pathways. Autophagy is an intracellular lysosomal degradation process by which invasive, damaged, or redundant cytoplasmic components, including microorganisms and defunct organelles, are removed to maintain cellular homeostasis. This process is particularly important in neurons that are required to cope with prolonged and sustained operational stress. Consequently, autophagy is a primary line of protection against neurodegenerative diseases. Parkinson's is caused by the loss of midbrain dopaminergic neurons (mDANs), resulting in progressive disruption of the nigrostriatal pathway, leading to motor, behavioural, and cognitive impairments. Mitochondrial dysfunction, with associated increases in oxidative stress, and declining proteostasis control, are key contributors during mDAN demise in Parkinson's. In this review, we analyse the crosstalk between autophagy and redoxtasis, including the molecular mechanisms involved and the detrimental effect of an imbalance in the pathogenesis of Parkinson's.
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110
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McQuade A, Kang YJ, Hasselmann J, Jairaman A, Sotelo A, Coburn M, Shabestari SK, Chadarevian JP, Fote G, Tu CH, Danhash E, Silva J, Martinez E, Cotman C, Prieto GA, Thompson LM, Steffan JS, Smith I, Davtyan H, Cahalan M, Cho H, Blurton-Jones M. Gene expression and functional deficits underlie TREM2-knockout microglia responses in human models of Alzheimer's disease. Nat Commun 2020; 11:5370. [PMID: 33097708 PMCID: PMC7584603 DOI: 10.1038/s41467-020-19227-5] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 09/30/2020] [Indexed: 12/11/2022] Open
Abstract
The discovery of TREM2 as a myeloid-specific Alzheimer's disease (AD) risk gene has accelerated research into the role of microglia in AD. While TREM2 mouse models have provided critical insight, the normal and disease-associated functions of TREM2 in human microglia remain unclear. To examine this question, we profile microglia differentiated from isogenic, CRISPR-modified TREM2-knockout induced pluripotent stem cell (iPSC) lines. By combining transcriptomic and functional analyses with a chimeric AD mouse model, we find that TREM2 deletion reduces microglial survival, impairs phagocytosis of key substrates including APOE, and inhibits SDF-1α/CXCR4-mediated chemotaxis, culminating in an impaired response to beta-amyloid plaques in vivo. Single-cell sequencing of xenotransplanted human microglia further highlights a loss of disease-associated microglial (DAM) responses in human TREM2 knockout microglia that we validate by flow cytometry and immunohistochemistry. Taken together, these studies reveal both conserved and novel aspects of human TREM2 biology that likely play critical roles in the development and progression of AD.
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Affiliation(s)
- Amanda McQuade
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - You Jung Kang
- grid.266859.60000 0000 8598 2218Department of Mechanical Engineering and Engineering Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Nanoscale Science Program, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Center for Biomedical Engineering and Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA
| | - Jonathan Hasselmann
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Amit Jairaman
- grid.266093.80000 0001 0668 7243Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697 USA
| | - Alexandra Sotelo
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Morgan Coburn
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Sepideh Kiani Shabestari
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Jean Paul Chadarevian
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Gianna Fote
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Christina H. Tu
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Emma Danhash
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Jorge Silva
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Eric Martinez
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Carl Cotman
- grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - G. Aleph Prieto
- grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.9486.30000 0001 2159 0001Institute of Neurobiology, National Autonomous University of Mexico, Queretaro, Mexico
| | - Leslie M. Thompson
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA
| | - Joan S. Steffan
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Department of Psychology and Human Behavior, University of California Irvine, Irvine, CA 92697 USA
| | - Ian Smith
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA
| | - Hayk Davtyan
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Michael Cahalan
- grid.266093.80000 0001 0668 7243Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697 USA
| | - Hansang Cho
- grid.266859.60000 0000 8598 2218Department of Mechanical Engineering and Engineering Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Nanoscale Science Program, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Center for Biomedical Engineering and Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.264381.a0000 0001 2181 989XDepartment of Biophysics, Sungkyunkwan University, Suwon, 16419 Korea
| | - Mathew Blurton-Jones
- Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA, 92697, USA. .,Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA, 92697, USA. .,Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA, 92697, USA.
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111
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Adnan G, Rubikaite A, Khan M, Reber M, Suetterlin P, Hindges R, Drescher U. The GTPase Arl8B Plays a Principle Role in the Positioning of Interstitial Axon Branches by Spatially Controlling Autophagosome and Lysosome Location. J Neurosci 2020; 40:8103-8118. [PMID: 32917789 PMCID: PMC7574663 DOI: 10.1523/jneurosci.1759-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 07/13/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
Interstitial axon branching is an essential step during the establishment of neuronal connectivity. However, the exact mechanisms on how the number and position of branches are determined are still not fully understood. Here, we investigated the role of Arl8B, an adaptor molecule between lysosomes and kinesins. In chick retinal ganglion cells (RGCs), downregulation of Arl8B reduces axon branch density and shifts their location more proximally, while Arl8B overexpression leads to increased density and more distal positions of branches. These alterations correlate with changes in the location and density of lysosomes and autophagosomes along the axon shaft. Diminishing autophagy directly by knock-down of atg7, a key autophagy gene, reduces branch density, while induction of autophagy by rapamycin increases axon branching, indicating that autophagy plays a prominent role in axon branch formation. In vivo, local inactivation of autophagy in the retina using a mouse conditional knock-out approach disturbs retino-collicular map formation which is dependent on the formation of interstitial axon branches. These data suggest that Arl8B plays a principal role in the positioning of axon branches by spatially controlling autophagy, thus directly controlling formation of neural connectivity in the brain.SIGNIFICANCE STATEMENT The formation of interstitial axonal branches plays a prominent role in numerous places of the developing brain during neural circuit establishment. We show here that the GTPase Arl8B controls density and location of interstitial axon branches, and at the same time controls also density and location of the autophagy machinery. Upregulation or downregulation of autophagy in vitro promotes or inhibits axon branching. Local disruption of autophagy in vivo disturbs retino-collicular mapping. Our data suggest that Arl8B controls axon branching by controlling locally autophagy. This work is one of the first reports showing a role of autophagy during early neural circuit development and suggests that autophagy in general plays a much more prominent role during brain development than previously anticipated.
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Affiliation(s)
- Gee Adnan
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Aine Rubikaite
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Moqadisa Khan
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
| | - Michael Reber
- Krembil Research Institute, Toronto, Ontario M5T 0S8, Canada
| | - Philip Suetterlin
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- Craniofacial Development and Stem Cell Biology, King's College London, Guy's Hospital, London SE1 9RT, United Kingdom
| | - Robert Hindges
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
| | - Uwe Drescher
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
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112
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Hou X, Watzlawik JO, Cook C, Liu C, Kang SS, Lin W, DeTure M, Heckman MG, Diehl NN, Al‐Shaikh FSH, Walton RL, Ross OA, Melrose HL, Ertekin‐Taner N, Bu G, Petrucelli L, Fryer JD, Murray ME, Dickson DW, Fiesel FC, Springer W. Mitophagy alterations in Alzheimer's disease are associated with granulovacuolar degeneration and early tau pathology. Alzheimers Dement 2020; 17:417-430. [PMID: 33090691 PMCID: PMC8048674 DOI: 10.1002/alz.12198] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 08/26/2020] [Accepted: 08/30/2020] [Indexed: 02/06/2023]
Abstract
INTRODUCTION The cytoprotective PTEN-induced kinase 1 (PINK1)-parkin RBR E3 ubiquitin protein ligase (PRKN) pathway selectively labels damaged mitochondria with phosphorylated ubiquitin (pS65-Ub) for their autophagic removal (mitophagy). Because dysfunctions of mitochondria and degradation pathways are early features of Alzheimer's disease (AD), mitophagy impairments may contribute to the pathogenesis. METHODS Morphology, levels, and distribution of the mitophagy tag pS65-Ub were evaluated by biochemical analyses combined with tissue and single cell imaging in AD autopsy brain and in transgenic mouse models. RESULTS Analyses revealed significant increases of pS65-Ub levels in AD brain, which strongly correlated with granulovacuolar degeneration (GVD) and early phospho-tau deposits, but were independent of amyloid beta pathology. Single cell analyses revealed predominant co-localization of pS65-Ub with mitochondria, GVD bodies, and/or lysosomes depending on the brain region analyzed. DISCUSSION Our study highlights mitophagy alterations in AD that are associated with early tau pathology, and suggests that distinct mitochondrial, autophagic, and/or lysosomal failure may contribute to the selective vulnerability in disease.
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Affiliation(s)
- Xu Hou
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | | | - Casey Cook
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | - Chia‐Chen Liu
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | - Silvia S. Kang
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | - Wen‐Lang Lin
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | - Michael DeTure
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
| | - Michael G. Heckman
- Division of Biomedical Statistics and InformaticsMayo ClinicJacksonvilleFloridaUSA
| | - Nancy N. Diehl
- Division of Biomedical Statistics and InformaticsMayo ClinicJacksonvilleFloridaUSA
| | | | | | - Owen A. Ross
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | | | - Nilüfer Ertekin‐Taner
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
- Department of NeurologyMayo ClinicJacksonvilleFloridaUSA
| | - Guojun Bu
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | - Leonard Petrucelli
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | - John D. Fryer
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | - Melissa E. Murray
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | - Dennis W. Dickson
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
| | | | - Wolfdieter Springer
- Department of NeuroscienceMayo ClinicJacksonvilleFloridaUSA
- Neuroscience PhD ProgramMayo Clinic Graduate School of Biomedical SciencesJacksonvilleFloridaUSA
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113
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Farfel-Becker T, Roney JC, Cheng XT, Li S, Cuddy SR, Sheng ZH. Neuronal Soma-Derived Degradative Lysosomes Are Continuously Delivered to Distal Axons to Maintain Local Degradation Capacity. Cell Rep 2020; 28:51-64.e4. [PMID: 31269450 PMCID: PMC6696943 DOI: 10.1016/j.celrep.2019.06.013] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/12/2019] [Accepted: 06/04/2019] [Indexed: 12/19/2022] Open
Abstract
Neurons face the challenge of maintaining cellular homeostasis through lysosomal degradation. While enzymatically active degradative lysosomes are enriched in the soma, their axonal trafficking and positioning and impact on axonal physiology remain elusive. Here, we characterized axon-targeted delivery of degradative lysosomes by applying fluorescent probes that selectively label active forms of lysosomal cathepsins D, B, L, and GCase. By time-lapse imaging of cortical neurons in microfluidic devices and standard dishes, we reveal that soma-derived degradative lysosomes rapidly influx into distal axons and target to autophagosomes and Parkinson disease-related α-synuclein cargos for local degradation. Impairing lysosome axonal delivery induces an aberrant accumulation of autophagosomes and α-synuclein cargos in distal axons. Our study demonstrates that the axon is an active compartment for local degradation and reveals fundamental aspects of axonal lysosomal delivery and maintenance. Our work establishes a foundation for investigations into axonal lysosome trafficking and functionality in neurodegenerative diseases.
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Affiliation(s)
- Tamar Farfel-Becker
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Joseph C Roney
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Xiu-Tang Cheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Sunan Li
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Sean R Cuddy
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA.
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114
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Hill SE, Colón-Ramos DA. The Journey of the Synaptic Autophagosome: A Cell Biological Perspective. Neuron 2020; 105:961-973. [PMID: 32191859 DOI: 10.1016/j.neuron.2020.01.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/23/2019] [Accepted: 01/14/2020] [Indexed: 01/13/2023]
Abstract
Autophagy is a key cellular degradative pathway, important for neuronal homeostasis and function. Disruption of autophagy is associated with neuronal dysfunction and neurodegeneration. Autophagy is compartmentalized in neurons, with specific stages of the pathway occurring in distinct subcellular compartments. Coordination of these stages drives progression of autophagy and enables clearance of substrates. Yet, we are only now learning how these distributed processes are integrated across the neuron. In this review, we focus on the cell biological course of autophagy in neurons, from biogenesis at the synapse to degradation in the soma. We describe how the steps of autophagy are distributed across neuronal subcellular compartments, how local machinery regulates autophagy, and the impact of coordinated regulation on neuronal physiology and disease. We also discuss how recent advances in our understanding of neuronal autophagic mechanisms have reframed how we think about the role of local regulation of autophagy in all tissues.
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Affiliation(s)
- Sarah E Hill
- Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine, PO Box 9812, New Haven, CT 06536-0812, USA; Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Daniel A Colón-Ramos
- Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine, PO Box 9812, New Haven, CT 06536-0812, USA; Instituto de Neurobiología José del Castillo, Universidad de Puerto Rico, San Juan, PR, USA.
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115
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Yamashima T, Ota T, Mizukoshi E, Nakamura H, Yamamoto Y, Kikuchi M, Yamashita T, Kaneko S. Intake of ω-6 Polyunsaturated Fatty Acid-Rich Vegetable Oils and Risk of Lifestyle Diseases. Adv Nutr 2020; 11:1489-1509. [PMID: 32623461 PMCID: PMC7666899 DOI: 10.1093/advances/nmaa072] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/30/2019] [Accepted: 05/26/2020] [Indexed: 12/28/2022] Open
Abstract
Although excessive consumption of deep-fried foods is regarded as 1 of the most important epidemiological factors of lifestyle diseases such as Alzheimer's disease, type 2 diabetes, and obesity, the exact mechanism remains unknown. This review aims to discuss whether heated cooking oil-derived peroxidation products cause cell degeneration/death for the occurrence of lifestyle diseases. Deep-fried foods cooked in ω-6 PUFA-rich vegetable oils such as rapeseed (canola), soybean, sunflower, and corn oils, already contain or intrinsically generate "hydroxynonenal" by peroxidation. As demonstrated previously, hydroxynonenal promotes carbonylation of heat-shock protein 70.1 (Hsp70.1), with the resultant impaired ability of cells to recycle damaged proteins and stabilize the lysosomal membrane. Until now, the implication of lysosomal/autophagy failure due to the daily consumption of ω-6 PUFA-rich vegetable oils in the progression of cell degeneration/death has not been reported. Since the "calpain-cathepsin hypothesis" was formulated as a cause of ischemic neuronal death in 1998, its relevance to Alzheimer's neuronal death has been suggested with particular attention to hydroxynonenal. However, its relevance to cell death of the hypothalamus, liver, and pancreas, especially related to appetite/energy control, is unknown. The hypothalamus senses information from both adipocyte-derived leptin and circulating free fatty acids. Concentrations of circulating fatty acid and its oxidized form, especially hydroxynonenal, are increased in obese and/or aged subjects. As overactivation of the fatty acid receptor G-protein coupled receptor 40 (GPR40) in response to excessive or oxidized fatty acids in these subjects may lead to the disruption of Ca2+ homeostasis, it should be evaluated whether GPR40 overactivation contributes to diverse cell death. Here, we describe the molecular implication of ω-6 PUFA-rich vegetable oil-derived hydroxynonenal in lysosomal destabilization leading to cell death. By oxidizing Hsp70.1, both the dietary PUFA- (exogenous) and the membrane phospholipid- (intrinsic) peroxidation product "hydroxynonenal," when combined, may play crucial roles in the occurrence of diverse lifestyle diseases including Alzheimer's disease.
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Affiliation(s)
| | | | | | | | - Yasuhiko Yamamoto
- Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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116
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Nicola R, Okun E. Food and Age: It Takes Two to Degenerate. Front Aging Neurosci 2020; 12:182. [PMID: 32676023 PMCID: PMC7333676 DOI: 10.3389/fnagi.2020.00182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 05/25/2020] [Indexed: 12/15/2022] Open
Affiliation(s)
- Raneen Nicola
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel.,The Paul Feder Laboratory on Alzheimer's Disease Research, Bar-Ilan University, Ramat Gan, Israel
| | - Eitan Okun
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel.,The Paul Feder Laboratory on Alzheimer's Disease Research, Bar-Ilan University, Ramat Gan, Israel.,The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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117
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Zhou F, Xiong X, Li S, Liang J, Zhang X, Tian M, Li X, Gao M, Tang L, Li Y. Enhanced autophagic retrograde axonal transport by dynein intermediate chain upregulation improves Aβ clearance and cognitive function in APP/PS1 double transgenic mice. Aging (Albany NY) 2020; 12:12142-12159. [PMID: 32584265 PMCID: PMC7343509 DOI: 10.18632/aging.103382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 05/23/2020] [Indexed: 02/07/2023]
Abstract
Autophagosome accumulation is observed in the distal axons of Alzheimer disease (AD) patients and AD animal models, suggesting that deficient retrograde transport and impaired autophagic clearance of beta-amyloid (A β) contribute to AD pathogenesis. Expression of the retrograde axonal transport-related protein dynein intermediate chain (DIC) is also reduced in AD patients, but the contributions of DIC to AD pathology remain elusive. This study investigated the effects of DIC expression levels on cognitive function, autophagosome axonal transport, and A β clearance in the APP/PS1 double transgenic mouse model of AD. Autophagic activity was enhanced in the hippocampus of young (3-month-old) AD mice, as evidenced by greater expression of autophagosome markers, lysosome markers, axonal transport motors (including DIC), and dynein regulatory proteins. The expression levels of autophagosome markers remained elevated, whereas those of autophagic and axonal transport proteins decreased progressively with age, accompanied by spatial learning and memory deficits, axonal autophagosome accumulation, and A β deposition. Knockdown of DIC exacerbated while overexpression improved axonal transport, autophagosome maturation, Aβ clearance, and spatial learning and memory in aged AD mice. Our study provides evidence that age-dependent failure of axonal autophagic flux contributes to AD-associated neuropathology and cognitive deficits, suggesting DIC as a potential therapeutic target for AD.
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Affiliation(s)
- Fanlin Zhou
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing 400030, China
| | - Xiaomin Xiong
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Shijie Li
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Jie Liang
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Xiong Zhang
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Mingyuan Tian
- Department of Endocrinology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Xiaoju Li
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Minna Gao
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Li Tang
- Department of Pathophysiology, Chongqing Medical University, Chongqing 400016, China
| | - Yu Li
- Institute of Neuroscience, School of Basic Medicine, Chongqing Medical University, Chongqing 400016, China.,Key Laboratory for Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing University Cancer Hospital, Chongqing 400044, China
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118
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Rusmini P, Cristofani R, Tedesco B, Ferrari V, Messi E, Piccolella M, Casarotto E, Chierichetti M, Cicardi ME, Galbiati M, Geroni C, Lombardi P, Crippa V, Poletti A. Enhanced Clearance of Neurotoxic Misfolded Proteins by the Natural Compound Berberine and Its Derivatives. Int J Mol Sci 2020; 21:ijms21103443. [PMID: 32414108 PMCID: PMC7279252 DOI: 10.3390/ijms21103443] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 12/17/2022] Open
Abstract
Background: Accumulation of misfolded proteins is a common hallmark of several neurodegenerative disorders (NDs) which results from a failure or an impairment of the protein quality control (PQC) system. The PQC system is composed by chaperones and the degradative systems (proteasome and autophagy). Mutant proteins that misfold are potentially neurotoxic, thus strategies aimed at preventing their aggregation or at enhancing their clearance are emerging as interesting therapeutic targets for NDs. Methods: We tested the natural alkaloid berberine (BBR) and some derivatives for their capability to enhance misfolded protein clearance in cell models of NDs, evaluating which degradative pathway mediates their action. Results: We found that both BBR and its semisynthetic derivatives promote degradation of mutant androgen receptor (ARpolyQ) causative of spinal and bulbar muscular atrophy, acting mainly via proteasome and preventing ARpolyQ aggregation. Overlapping effects were observed on other misfolded proteins causative of amyotrophic lateral sclerosis, frontotemporal-lobar degeneration or Huntington disease, but with selective and specific action against each different mutant protein. Conclusions: BBR and its analogues induce the clearance of misfolded proteins responsible for NDs, representing potential therapeutic tools to counteract these fatal disorders.
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Affiliation(s)
- Paola Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Riccardo Cristofani
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Barbara Tedesco
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Veronica Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Elio Messi
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Margherita Piccolella
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Elena Casarotto
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Marta Chierichetti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Maria Elena Cicardi
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
- Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Mariarita Galbiati
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Cristina Geroni
- Naxospharma srl, Novate Milanese, 20026 Milan, Italy; (C.G.); (P.L.)
| | - Paolo Lombardi
- Naxospharma srl, Novate Milanese, 20026 Milan, Italy; (C.G.); (P.L.)
| | - Valeria Crippa
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
| | - Angelo Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Dipartimento di Eccellenza 2018-2022, Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, 20133 Milan, Italy; (P.R.); (R.C.); (B.T.); (V.F.); (E.M.); (M.P.); (E.C.); (M.C.); (M.E.C.); (M.G.); (V.C.)
- Correspondence:
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119
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Tomoda T, Yang K, Sawa A. Neuronal Autophagy in Synaptic Functions and Psychiatric Disorders. Biol Psychiatry 2020; 87:787-796. [PMID: 31542152 PMCID: PMC6986983 DOI: 10.1016/j.biopsych.2019.07.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/02/2019] [Accepted: 07/19/2019] [Indexed: 12/22/2022]
Abstract
Homeostatic maintenance of physiological functions is fundamental to organismal well-being. Disruption or imbalance in homeostasis results in functional disturbances at molecular, cellular, and tissue levels, leading to manifestation as physical and mental illnesses. Homeostatic imbalance is caused by a range of pathophysiological mechanisms, including disrupted reduction-oxidation reactions, inflammatory responses, metabolic disturbances, or failure in quality control of cellular proteins and organelles. However, the roles for the protein/organelle quality control in the regulation of behaviors, in particular of cognitive processes, had not been well documented, until recent reports finally supported this concept. The frontline studies in neuroscience have revealed that synaptic components (e.g., synaptic proteins, organelles, neurotransmitters and their receptors) are selectively degraded by autophagy, a cellular recycling machinery implicated in surveillance and quality control of proteins and organelles responsible for the maintenance of cellular homeostasis. Apart from the canonical role of autophagy in supporting cell viability, synaptic autophagy appears to regulate synapse remodeling and plasticity. Consistently, emerging evidence suggests novel roles of autophagy in memory encoding, information processing, or cognitive functions. In this review, we overview recent progress in understanding the roles of neuronal autophagy in homeostatic maintenance of synaptic functions, with particular focus on how disruptions in these processes may contribute to the pathophysiology of psychiatric disorders.
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Affiliation(s)
- Toshifumi Tomoda
- Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
| | - Kun Yang
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
| | - Akira Sawa
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
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120
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Chen S, Tian R, Luo D, Xiao Z, Li H, Lin D. Time-Course Changes and Role of Autophagy in Primary Spinal Motor Neurons Subjected to Oxygen-Glucose Deprivation: Insights Into Autophagy Changes in a Cellular Model of Spinal Cord Ischemia. Front Cell Neurosci 2020; 14:38. [PMID: 32265654 PMCID: PMC7098962 DOI: 10.3389/fncel.2020.00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 02/07/2020] [Indexed: 02/06/2023] Open
Abstract
Spinal cord ischemia is a severe clinical complication induced by thoracoabdominal aortic surgery, severe trauma, or compression to the spinal column. As one of the most important functional cells in the spinal cord, spinal motor neurons (SMNs) suffer most during the process since they are vulnerable to ischemic injury due to high demands of energy. Previous researches have tried various animal models or organotypic tissue experiments to mimic the process and get to know the pathogenesis and mechanism. However, little work has been performed on the cellular model of spinal cord ischemia, which has been hampered by the inability to obtain a sufficient number of pure primary SMNs for in vitro study. By optimizing the isolation and culture of SMNs, our laboratory has developed an improved culture system of primary SMNs, which allows cellular models and thus mechanism studies. In the present study, by establishing an in vitro model of spinal cord ischemia, we intended to observe the dynamic time-course changes of SMNs and investigate the role of autophagy in SMNs during the process. It was found that oxygen-glucose deprivation (OGD) resulted in destruction of neural networks and decreased cell viability of primary SMNs, and the severity increased with the prolonging of the OGD time. The OGD treatment enhanced autophagy, which reached a peak at 5 h. Further investigation demonstrated that inhibition of autophagy exacerbated the injury, evidencing that autophagy plays a protective role during the process.
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Affiliation(s)
- Shudong Chen
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ruimin Tian
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Guangdong Provincial Academy of Chinese Medical Sciences, Guangzhou, China
| | - Dan Luo
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhifeng Xiao
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hui Li
- School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Dingkun Lin
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Guangdong Provincial Academy of Chinese Medical Sciences, Guangzhou, China
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121
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Fan Y, You G. Proteasome Inhibitors Bortezomib and Carfilzomib Stimulate the Transport Activity of Human Organic Anion Transporter 1. Mol Pharmacol 2020; 97:384-391. [PMID: 32234809 DOI: 10.1124/mol.119.118653] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/10/2020] [Indexed: 01/08/2023] Open
Abstract
Organic anion transporter 1 (OAT1), expressed at the basolateral membrane of renal proximal tubule epithelial cells, mediates the renal excretion of many clinically important drugs. Previous study in our laboratory demonstrated that ubiquitin conjugation to OAT1 leads to OAT1 internalization from the cell surface and subsequent degradation. The current study showed that the ubiquitinated OAT1 accumulated in the presence of the proteasomal inhibitors MG132 and ALLN rather than the lysosomal inhibitors leupeptin and pepstatin A, suggesting that ubiquitinated OAT1 degrades through proteasomes. Anticancer drugs bortezomib and carfilzomib target the ubiquitin-proteasome pathway. We therefore investigate the roles of bortezomib and carfilzomib in reversing the ubiquitination-induced downregulation of OAT1 expression and transport activity. We showed that bortezomib and carfilzomib extremely increased the ubiquitinated OAT1, which correlated well with an enhanced OAT1-mediated transport of p-aminohippuric acid and an enhanced OAT1 surface expression. The augmented OAT1 expression and transport activity after the treatment with bortezomib and carfilzomib resulted from a reduced rate of OAT1 degradation. Consistent with this, we found decreased 20S proteasomal activity in cells that were exposed to bortezomib and carfilzomib. In conclusion, this study identified the pathway in which ubiquitinated OAT1 degrades and unveiled a novel role of anticancer drugs bortezomib and carfilzomib in their regulation of OAT1 expression and transport activity. SIGNIFICANCE STATEMENT: Bortezomib and carfilzomib are two Food and Drug Administration-approved anticancer drugs, and proteasome is the drug target. In this study, we unveiled a new role of bortezomib and carfilzomib in enhancing OAT1 expression and transport activity by preventing the degradation of ubiquitinated OAT1 in proteasomes. This finding provides a new strategy in regulating OAT1 function that can be used to accelerate the clearance of drugs, metabolites, or toxins and reverse the decreased expression under disease conditions.
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Affiliation(s)
- Yunzhou Fan
- Department of Pharmaceutics, Rutgers, the State University of New Jersey, Piscataway, New Jersey
| | - Guofeng You
- Department of Pharmaceutics, Rutgers, the State University of New Jersey, Piscataway, New Jersey
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122
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Wallings R, Connor-Robson N, Wade-Martins R. LRRK2 interacts with the vacuolar-type H+-ATPase pump a1 subunit to regulate lysosomal function. Hum Mol Genet 2020; 28:2696-2710. [PMID: 31039583 PMCID: PMC6687951 DOI: 10.1093/hmg/ddz088] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 02/20/2019] [Accepted: 04/15/2019] [Indexed: 12/11/2022] Open
Abstract
Lysosomal dysfunction lies at the centre of the cellular mechanisms underlying Parkinson’s disease although the precise underlying mechanisms remain unknown. We investigated the role of leucine-rich repeat kinase 2 (LRRK2) on lysosome biology and the autophagy pathway in primary neurons expressing the human LRRK2-G2019S or LRKK2-R1441C mutant or the human wild-type (hWT-LRRK2) genomic locus. The expression of LRRK2-G2019S or hWT-LRRK2 inhibited autophagosome production, whereas LRRK2-R1441C induced a decrease in autophagosome/lysosome fusion and increased lysosomal pH. In vivo data from the cortex and substantia nigra pars compacta of aged LRRK2 transgenic animals revealed alterations in autophagosome puncta number reflecting those phenotypes seen in vitro. Using the two selective and potent LRRK2 kinase inhibitors, MLi-2 and PF-06447475, we demonstrated that the LRRK2-R1441C-mediated decrease in autolysosome maturation is not dependent on LRRK2 kinase activity. We showed that hWT-LRRK2 and LRRK2-G2019S bind to the a1 subunit of vATPase, which is abolished by the LRRK2-R1441C mutation, leading to a decrease in a1 protein and cellular mislocalization. Modulation of lysosomal zinc increased vATPase a1 protein levels and rescued the LRRK2-R1441C-mediated cellular phenotypes. Our work defines a novel interaction between the LRRK2 protein and the vATPase a1 subunit and demonstrates a mode of action by which drugs may rescue lysosomal dysfunction. These results demonstrate the importance of LRRK2 in lysosomal biology, as well as the critical role of the lysosome in PD.
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Affiliation(s)
- Rebecca Wallings
- Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Natalie Connor-Robson
- Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Richard Wade-Martins
- Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
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123
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Tran AP, Warren PM, Silver J. Regulation of autophagy by inhibitory CSPG interactions with receptor PTPσ and its impact on plasticity and regeneration after spinal cord injury. Exp Neurol 2020; 328:113276. [PMID: 32145250 DOI: 10.1016/j.expneurol.2020.113276] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 12/15/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs), extracellular matrix molecules that increase dramatically following a variety of CNS injuries or diseases, have long been known for their potent capacity to curtail cell migrations as well as axon regeneration and sprouting. The inhibition can be conferred through binding to their major cognate receptor, Protein Tyrosine Phosphatase Sigma (PTPσ). However, the precise mechanisms downstream of receptor binding that mediate growth inhibition have remained elusive. Recently, CSPGs/PTPσ interactions were found to regulate autophagic flux at the axon growth cone by dampening the autophagosome-lysosomal fusion step. Because of the intense interest in autophagic phenomena in the regulation of a wide variety of critical cellular functions, we summarize here what is currently known about dysregulation of autophagy following spinal cord injury, and highlight this critical new mechanism underlying axon regeneration failure. Furthermore, we review how CSPGs/PTPσ interactions influence plasticity through autophagic regulation and how PTPσ serves as a switch to execute either axon outgrowth or synaptogenesis. This has exciting implications for the role CSPGs play not only in axon regeneration failure after spinal cord injury, but also in neurodegenerative diseases where, again, inhibitory CSPGs are upregulated.
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Affiliation(s)
- Amanda Phuong Tran
- Seattle Children's Hospital Research Institute, Integrative Center for Brain Research, Seattle, Washington, USA
| | - Philippa Mary Warren
- King's College London, Regeneration Group, The Wolfson Centre for Age-Related Diseases, Guy's Campus, London Bridge, London, UK
| | - Jerry Silver
- Case Western Reserve University, School of Medicine, Department of Neurosciences, Cleveland, OH, USA.
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124
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Ivankovic D, Drew J, Lesept F, White IJ, López Doménech G, Tooze SA, Kittler JT. Axonal autophagosome maturation defect through failure of ATG9A sorting underpins pathology in AP-4 deficiency syndrome. Autophagy 2020; 16:391-407. [PMID: 31142229 PMCID: PMC6999640 DOI: 10.1080/15548627.2019.1615302] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 04/02/2019] [Accepted: 04/29/2019] [Indexed: 12/26/2022] Open
Abstract
Adaptor protein (AP) complexes mediate key sorting decisions in the cell through selective incorporation of transmembrane proteins into vesicles. Little is known of the roles of AP-4, despite its loss of function leading to a severe early onset neurological disorder, AP-4 deficiency syndrome. Here we demonstrate an AP-4 epsilon subunit knockout mouse model that recapitulates characteristic neuroanatomical phenotypes of AP-4 deficiency patients. We show that ATG9A, critical for autophagosome biogenesis, is an AP-4 cargo, which is retained within the trans-Golgi network (TGN) in vivo and in culture when AP-4 function is lost. TGN retention results in depletion of axonal ATG9A, leading to defective autophagosome generation and aberrant expansions of the distal axon. The reduction in the capacity to generate axonal autophagosomes leads to defective axonal extension and de novo generation of distal axonal swellings containing accumulated ER, underlying the impaired axonal integrity in AP-4 deficiency syndrome.Abbreviations: AP: adaptor protein; AP4B1: adaptor-related protein complex AP-4, beta 1; AP4E1: adaptor-related protein complex AP-4, epsilon 1; ATG: autophagy-related; EBSS: Earle's balanced salt solution; ER: endoplasmic reticulum; GFAP: glial fibrillary acidic protein; GOLGA1/Golgin-97/GOLG97: golgi autoantigen, golgin subfamily a, 1; GOLGA2/GM130: golgi autoantigen, golgin subfamily a, 2; HSP: hereditary spastic paraplegia; LC3/MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MAP2: microtubule-associated protein 2; MAPK8IP1/JIP1: mitogen-acitvated protein kinase 8 interacting protein 1; NEFH/NF200: neurofilament, heavy polypeptide; RBFOX3/NeuN (RNA binding protein, fox-1 homolog [C. elegans] 3); SQSTM1/p62: sequestosome 1; TGN: trans-Golgi network; WIPI2: WD repeat domain, phosphoinositide interacting protein 2.
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Affiliation(s)
| | - James Drew
- Neuroscience, Physiology and Pharmacology, UCL, London, UK
| | - Flavie Lesept
- Neuroscience, Physiology and Pharmacology, UCL, London, UK
| | - Ian J. White
- MRC Laboratory for Molecular Cell Biology, UCL, London, UK
| | | | - Sharon A. Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, UK
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Aravamudhan P, Raghunathan K, Konopka-Anstadt J, Pathak A, Sutherland DM, Carter BD, Dermody TS. Reovirus uses macropinocytosis-mediated entry and fast axonal transport to infect neurons. PLoS Pathog 2020; 16:e1008380. [PMID: 32109948 PMCID: PMC7065821 DOI: 10.1371/journal.ppat.1008380] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 03/11/2020] [Accepted: 02/04/2020] [Indexed: 12/12/2022] Open
Abstract
Several barriers protect the central nervous system (CNS) from pathogen invasion. Yet viral infections of the CNS are common and often debilitating. Understanding how neurotropic viruses co-opt host machinery to overcome challenges to neuronal entry and transmission is important to combat these infections. Neurotropic reovirus disseminates through neural routes and invades the CNS to cause lethal encephalitis in newborn animals. To define mechanisms of reovirus neuronal entry and directional transport, we used primary neuron cultures, which reproduce in vivo infection patterns displayed by different reovirus serotypes. Treatment of neurons with small-molecule inhibitors of different endocytic uptake pathways allowed us to discover that the cellular machinery mediating macropinocytosis is required for reovirus neuronal entry. This mechanism of reovirus entry differs from clathrin-mediated endocytosis, which is used by reovirus to invade non-neuronal cells. Analysis of reovirus transport and release from isolated soma or axonal termini of neurons cultivated in microfluidic devices indicates that reovirus is capable of retrograde but only limited anterograde neuronal transmission. The dynamics of retrograde reovirus movement are consistent with fast axonal transport coordinated by dynein along microtubules. Further analysis of viral transport revealed that multiple virions are transported together in axons within non-acidified vesicles. Reovirus-containing vesicles acidify after reaching the soma, where disassembly of virions and release of the viral core into the cytoplasm initiates replication. These results define mechanisms of reovirus neuronal entry and transport and establish a foundation to identify common host factors used by neuroinvasive viruses. Furthermore, our findings emphasize consideration of cell type-specific entry mechanisms in the tailored design of neurotropic viruses as tracers, oncolytic agents, and delivery vectors. Viral infections of the central nervous system (CNS) cause a significant health burden globally and compel a better mechanistic understanding of neural invasion by viruses to develop effective interventions. Neurotropic reovirus disseminates through neural routes to infect the CNS and serves as a tractable model to study neural invasion by viruses. Despite knowledge of reovirus neurotropism for decades, mechanisms mediating reovirus neuronal infection remain undefined. We used primary neurons cultured in microfluidic devices to study entry and directional transport of reovirus. We discovered that reovirus uses macropinocytosis for neuronal entry as opposed to the use of a clathrin-mediated pathway in non-neuronal cells. We are unaware of another virus using macropinocytosis to enter neurons. Following internalization, reovirus spreads in the retrograde direction using dynein-mediated fast axonal transport but exhibits limited anterograde spread. We further demonstrate that reovirus disassembly and replication occur in the neuronal soma subsequent to axonal transport. Remarkably, these entry and transport mechanisms mirror those used by misfolded proteins implicated in neurodegenerative diseases. Our findings establish the mechanics of reovirus neuronal uptake and spread and provide clues about therapeutic targets to limit neuropathology inflicted by pathogens and misfolded proteins.
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Affiliation(s)
- Pavithra Aravamudhan
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Krishnan Raghunathan
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jennifer Konopka-Anstadt
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Amrita Pathak
- Department of Biochemistry and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Danica M. Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bruce D. Carter
- Department of Biochemistry and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Terence S. Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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126
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Han K, Kim SH, Choi M. Computational modeling of the effects of autophagy on amyloid-β peptide levels. Theor Biol Med Model 2020; 17:2. [PMID: 32102666 PMCID: PMC7045373 DOI: 10.1186/s12976-020-00119-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/11/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Autophagy is an evolutionarily conserved intracellular process that is used for delivering proteins and organelles to the lysosome for degradation. For decades, autophagy has been speculated to regulate amyloid-β peptide (Aβ) accumulation, which is involved in Alzheimer's disease (AD); however, specific autophagic effects on the Aβ kinetics only have begun to be explored. RESULTS We develop a mathematical model for autophagy with respect to Aβ kinetics and perform simulations to understand the quantitative relationship between Aβ levels and autophagy activity. In the case of an abnormal increase in the Aβ generation, the degradation, secretion, and clearance rates of Aβ are significantly changed, leading to increased levels of Aβ. When the autophagic Aβ degradation is defective in addition to the increased Aβ generation, the Aβ-regulation failure is accompanied by elevated concentrations of autophagosome and autolysosome, which may further clog neurons. CONCLUSIONS The model predicts that modulations of different steps of the autophagy pathway (i.e., Aβ sequestration, autophagosome maturation, and intralysosomal hydrolysis) have significant step-specific and combined effects on the Aβ levels and thus suggests therapeutic and preventive implications of autophagy in AD.
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Affiliation(s)
- Kyungreem Han
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Soon Ho Kim
- Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul, South Korea
| | - MooYoung Choi
- Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul, South Korea.
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127
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Bodakuntla S, Schnitzler A, Villablanca C, Gonzalez-Billault C, Bieche I, Janke C, Magiera MM. Tubulin polyglutamylation is a general traffic-control mechanism in hippocampal neurons. J Cell Sci 2020; 133:jcs241802. [PMID: 31932508 DOI: 10.1242/jcs.241802] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/23/2019] [Indexed: 08/31/2023] Open
Abstract
Neurons are highly complex cells that heavily rely on intracellular transport to distribute a range of functionally essential cargoes within the cell. Post-translational modifications of tubulin are emerging as mechanisms for regulating microtubule functions, but their impact on neuronal transport is only marginally understood. Here, we have systematically studied the impact of post-translational polyglutamylation on axonal transport. In cultured hippocampal neurons, deletion of a single deglutamylase, CCP1 (also known as AGTPBP1), is sufficient to induce abnormal accumulation of polyglutamylation, i.e. hyperglutamylation. We next investigated how hyperglutamylation affects axonal transport of a range of functionally different neuronal cargoes: mitochondria, lysosomes, LAMP1 endosomes and BDNF vesicles. Strikingly, we found a reduced motility for all these cargoes, suggesting that polyglutamylation could act as a regulator of cargo transport in neurons. This, together with the recent discovery that hyperglutamylation induces neurodegeneration, makes it likely that perturbed neuronal trafficking could be one of the central molecular causes underlying this novel type of degeneration.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Satish Bodakuntla
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
| | - Anne Schnitzler
- Institut Curie, PSL Research University, Department of Genetics, F-75005 Paris, France
| | - Cristopher Villablanca
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago 7800003, Chile
- Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile
| | - Christian Gonzalez-Billault
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago 7800003, Chile
- Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile
| | - Ivan Bieche
- Institut Curie, PSL Research University, Department of Genetics, F-75005 Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, F-75005 Paris, France
| | - Carsten Janke
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
| | - Maria M Magiera
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
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128
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Affiliation(s)
- Xiang-Na Guo
- Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xin Ma
- Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
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129
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Evans CS, Holzbaur EL. Degradation of engulfed mitochondria is rate-limiting in Optineurin-mediated mitophagy in neurons. eLife 2020; 9:50260. [PMID: 31934852 PMCID: PMC6959996 DOI: 10.7554/elife.50260] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 12/19/2019] [Indexed: 12/19/2022] Open
Abstract
Mitophagy, the selective removal of damaged mitochondria, is thought to be critical to maintain neuronal homeostasis. Mutations of proteins in the pathway cause neurodegenerative diseases, suggesting defective mitochondrial turnover contributes to neurodegeneration. In primary rat hippocampal neurons, we developed a mitophagy induction paradigm where mild oxidative stress induced low levels of mitochondrial damage. Mitophagy-associated proteins were sequentially recruited to depolarized mitochondria followed by sequestration into autophagosomes. The localization of these mitophagy events had a robust somal bias. In basal and induced conditions, engulfed mitochondria remained in non-acidified organelles for hours to days, illustrating efficient autophagosome sequestration but delayed lysosomal fusion or acidification. Furthermore, expression of an ALS-linked mutation in the pathway disrupted mitochondrial network integrity and this effect was exacerbated by oxidative stress. Thus, age-related decline in neuronal health or expression of disease-associated mutations in the pathway may exacerbate the slow kinetics of neuronal mitophagy, leading to neurodegeneration.
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Affiliation(s)
- Chantell S Evans
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Erika Lf Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
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130
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Cai Q, Jeong YY. Mitophagy in Alzheimer's Disease and Other Age-Related Neurodegenerative Diseases. Cells 2020; 9:cells9010150. [PMID: 31936292 PMCID: PMC7017092 DOI: 10.3390/cells9010150] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/03/2020] [Accepted: 01/05/2020] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial dysfunction is a central aspect of aging and neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Mitochondria are the main cellular energy powerhouses, supplying most of ATP by oxidative phosphorylation, which is required to fuel essential neuronal functions. Efficient removal of aged and dysfunctional mitochondria through mitophagy, a cargo-selective autophagy, is crucial for mitochondrial maintenance and neuronal health. Mechanistic studies into mitophagy have highlighted an integrated and elaborate cellular network that can regulate mitochondrial turnover. In this review, we provide an updated overview of the recent discoveries and advancements on the mitophagy pathways and discuss the molecular mechanisms underlying mitophagy defects in Alzheimer's disease and other age-related neurodegenerative diseases, as well as the therapeutic potential of mitophagy-enhancing strategies to combat these disorders.
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131
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Zhao Y, Zhang Y, Zhang J, Zhang X, Yang G. Molecular Mechanism of Autophagy: Its Role in the Therapy of Alzheimer's Disease. Curr Neuropharmacol 2020; 18:720-739. [PMID: 31934838 PMCID: PMC7536828 DOI: 10.2174/1570159x18666200114163636] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/04/2019] [Accepted: 01/11/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder of progressive dementia that is characterized by the accumulation of beta-amyloid (Aβ)-containing neuritic plaques and intracellular Tau protein tangles. This distinctive pathology indicates that the protein quality control is compromised in AD. Autophagy functions as a "neuronal housekeeper" that eliminates aberrant protein aggregates by wrapping then into autophagosomes and delivering them to lysosomes for degradation. Several studies have suggested that autophagy deficits in autophagy participate in the accumulation and propagation of misfolded proteins (including Aβ and Tau). In this review, we summarize current knowledge of autophagy in the pathogenesis of AD, as well as some pathways targeting the restoration of autophagy. Moreover, we discuss how these aspects can contribute to the development of disease-modifying therapies in AD.
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Affiliation(s)
| | | | | | | | - Guofeng Yang
- Address correspondence to this author at the Department of Geriatrics, Second Hospital of Hebei Medical University, 215 Hepingxi Road, Shijiazhuang, 050000, China; Tel: +86-311-66636243; E-mail:
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132
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Henderson MX, Sedor S, McGeary I, Cornblath EJ, Peng C, Riddle DM, Li HL, Zhang B, Brown HJ, Olufemi MF, Bassett DS, Trojanowski JQ, Lee VMY. Glucocerebrosidase Activity Modulates Neuronal Susceptibility to Pathological α-Synuclein Insult. Neuron 2019; 105:822-836.e7. [PMID: 31899072 DOI: 10.1016/j.neuron.2019.12.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 11/05/2019] [Accepted: 12/04/2019] [Indexed: 10/25/2022]
Abstract
Mutations in the GBA1 gene are the most common genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB). GBA1 encodes the lysosomal lipid hydrolase glucocerebrosidase (GCase), and its activity has been linked to accumulation of α-synuclein. The current study systematically examines the relationship between GCase activity and both pathogenic and non-pathogenic forms of α-synuclein in primary hippocampal, cortical, and midbrain neuron and astrocyte cultures, as well as in transgenic mice and a non-transgenic mouse model of PD. We find that reduced GCase activity does not result in aggregation of α-synuclein. However, in the context of extant misfolded α-synuclein, GCase activity modulates neuronal susceptibility to pathology. Furthermore, this modulation does not depend on neuron type but rather is driven by the level of pathological α-synuclein seeds. This study has implications for understanding how GBA1 mutations influence PD pathogenesis and provides a platform for testing novel therapeutics.
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Affiliation(s)
- Michael X Henderson
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Samantha Sedor
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ian McGeary
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eli J Cornblath
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chao Peng
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dawn M Riddle
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Howard L Li
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Bin Zhang
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hannah J Brown
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Modupe F Olufemi
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Danielle S Bassett
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Electrical & Systems Engineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Physics & Astronomy, College of Arts & Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Santa Fe Institute, Santa Fe, NM 87501, USA
| | - John Q Trojanowski
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Virginia M Y Lee
- Institute on Aging and Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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133
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Lysosomes as dynamic regulators of cell and organismal homeostasis. Nat Rev Mol Cell Biol 2019; 21:101-118. [DOI: 10.1038/s41580-019-0185-4] [Citation(s) in RCA: 408] [Impact Index Per Article: 81.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2019] [Indexed: 12/11/2022]
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134
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Telegina DV, Suvorov GK, Kozhevnikova OS, Kolosova NG. Mechanisms of Neuronal Death in the Cerebral Cortex during Aging and Development of Alzheimer's Disease-Like Pathology in Rats. Int J Mol Sci 2019; 20:ijms20225632. [PMID: 31717998 PMCID: PMC6888576 DOI: 10.3390/ijms20225632] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/01/2019] [Accepted: 11/07/2019] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is the commonest type of late-life dementia and damages the cerebral cortex, a vulnerable brain region implicated in memory, emotion, cognition, and decision-making behavior. AD is characterized by progressive neuronal loss, but the mechanisms of cell death at different stages of the disease remain unknown. Here, by means of OXYS rats as an appropriate model of the most common (sporadic) AD form, we studied the main pathways of cell death during development of AD-like pathology, including the preclinical stage. We found that apoptosis is activated at the pre-symptomatic stage (age 20 days) correlating with the retardation of brain development in the OXYS strain early in life. Progression of the AD-like pathology was accompanied by activation of apoptosis and necroptosis resulting from a decline of autophagy-mediated proteostasis. Our results are consistent with the idea that the nature of changes in the pathways of apoptosis, autophagy, and necrosis depends on the stage of AD.
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Affiliation(s)
- Darya V. Telegina
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Pr. Lavrentyeva 10, Novosibirsk 630090, Russia; (D.V.T.); (G.K.S.); (O.S.K.)
| | - Gleb K. Suvorov
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Pr. Lavrentyeva 10, Novosibirsk 630090, Russia; (D.V.T.); (G.K.S.); (O.S.K.)
| | - Oyuna S. Kozhevnikova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Pr. Lavrentyeva 10, Novosibirsk 630090, Russia; (D.V.T.); (G.K.S.); (O.S.K.)
| | - Nataliya G. Kolosova
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Pr. Lavrentyeva 10, Novosibirsk 630090, Russia; (D.V.T.); (G.K.S.); (O.S.K.)
- Novosibirsk State University, 1 Pirogova str., Novosibirsk 630090, Russia
- Correspondence: ; Tel.: +7-383-363-4963 (ext. 4109)
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135
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Fischer RA, Risner ML, Roux AL, Wareham LK, Sappington RM. Impairment of Membrane Repolarization Accompanies Axon Transport Deficits in Glaucoma. Front Neurosci 2019; 13:1139. [PMID: 31736686 PMCID: PMC6838637 DOI: 10.3389/fnins.2019.01139] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/09/2019] [Indexed: 12/12/2022] Open
Abstract
Glaucoma is a leading cause of blindness worldwide, resulting from degeneration of retinal ganglion cells (RGCs), which form the optic nerve. In glaucoma, axon transport deficits appear to precede structural degeneration of RGC axons. The period of time between the onset of axon transport deficits and the structural degeneration of RGC axons may represent a therapeutic window for the prevention of irreversible vision loss. However, it is unclear how deficits in axon transport relate to the electrophysiological capacity of RGCs to produce and maintain firing frequencies that encode visual stimuli. Here, we examined the electrophysiological signature of individual RGCs in glaucomatous retina with respect to axon transport facility. Utilizing the Microbead Occlusion Model of murine ocular hypertension, we performed electrophysiological recordings of RGCs with and without deficits in anterograde axon transport. We found that RGCs with deficits in axon transport have a reduced ability to maintain spiking frequency that arises from elongation of the repolarization phase of the action potential. This repolarization phenotype arises from reduced cation flux and K+ dyshomeostasis that accompanies pressure-induced decreases in Na/K-ATPase expression and activity. In vitro studies with purified RGCs indicate that elevated pressure induces early internalization of Na/K-ATPase that, when reversed, stabilizes cation flux and prevents K+ dyshomeostasis. Furthermore, pharmacological inhibition of the Na/K-ATPase is sufficient to replicate pressure-induced cation influx and repolarization phase phenotypes in healthy RGCs. These studies suggest that deficits in axon transport also likely reflect impaired electrophysiological function of RGCs. Our findings further identify a failure to maintain electrochemical gradients and cation dyshomeostasis as an early phenotype of glaucomatous pathology in RGCs that may have significant bearing on efforts to restore RGC health in diseased retina.
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Affiliation(s)
- Rachel A Fischer
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Michael L Risner
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Abigail L Roux
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Lauren K Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Rebecca M Sappington
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
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136
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Cerri S, Blandini F. Role of Autophagy in Parkinson's Disease. Curr Med Chem 2019; 26:3702-3718. [PMID: 29484979 DOI: 10.2174/0929867325666180226094351] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 01/30/2018] [Accepted: 02/13/2018] [Indexed: 12/11/2022]
Abstract
Autophagy is an essential catabolic mechanism that delivers misfolded proteins and damaged organelles to the lysosome for degradation. Autophagy pathways include macroautophagy, chaperone-mediated autophagy and microautophagy, each involving different mechanisms of substrate delivery to lysosome. Defects of these pathways and the resulting accumulation of protein aggregates represent a common pathobiological feature of neurodegenerative disorders such as Alzheimer, Parkinson and Huntington disease. This review provides an overview of the role of autophagy in Parkinson's disease (PD) by summarizing the most relevant genetic and experimental evidence showing how this process can contribute to disease pathogenesis. Given lysosomes take part in the final step of the autophagic process, the role of lysosomal defects in the impairment of autophagy and their impact on disease will also be discussed. A glance on the role of non-neuronal autophagy in the pathogenesis of PD will be included. Moreover, we will examine novel pharmacological targets and therapeutic strategies that, by boosting autophagy, may be theoretically beneficial for PD. Special attention will be focused on natural products, such as phenolic compounds, that are receiving increasing consideration due to their potential efficacy associated with low toxicity. Although many efforts have been made to elucidate autophagic process, the development of new therapeutic interventions requires a deeper understanding of the mechanisms that may lead to autophagy defects in PD and should take into account the multifactorial nature of the disease as well as the phenotypic heterogeneity of PD patients.
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Affiliation(s)
- Silvia Cerri
- Laboratory of Cellular and Molecular Neurobiology, IRCCS Mondino Foundation, Pavia, Italy
| | - Fabio Blandini
- Laboratory of Cellular and Molecular Neurobiology, IRCCS Mondino Foundation, Pavia, Italy
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137
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Sub-nanomolar sensitive GZnP3 reveals TRPML1-mediated neuronal Zn 2+ signals. Nat Commun 2019; 10:4806. [PMID: 31641116 PMCID: PMC6805855 DOI: 10.1038/s41467-019-12761-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 09/27/2019] [Indexed: 02/07/2023] Open
Abstract
Although numerous fluorescent Zn2+ sensors have been reported, it is unclear whether and how Zn2+ can be released from the intracellular compartments into the cytosol due to a lack of probes that can detect physiological dynamics of cytosolic Zn2+. Here, we create a genetically encoded sensor, GZnP3, which demonstrates unprecedented sensitivity for Zn2+ at sub-nanomolar concentrations. Using GZnP3 as well as GZnP3-derived vesicular targeted probes, we provide the first direct evidence that Zn2+ can be released from endolysosomal vesicles to the cytosol in primary hippocampal neurons through the TRPML1 channel. Such TRPML1-mediated Zn2+ signals are distinct from Ca2+ in that they are selectively present in neurons, sustain longer, and are significantly higher in neurites as compared to the soma. Together, our work not only creates highly sensitive probes for investigating sub-nanomolar Zn2+ dynamics, but also reveals new pools of Zn2+ signals that can play critical roles in neuronal function. Numerous fluorescent Zn2+ sensors are available but most are unsuitable to detect physiological dynamics of cytosolic Zn2+. In this study, the authors present a genetically encoded sensor with sub-nanomolar sensitivity and show that Zn2 + is released from endolysosomal vesicles via TRPML1 in neurons.
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138
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The Endolysosomal System and Proteostasis: From Development to Degeneration. J Neurosci 2019; 38:9364-9374. [PMID: 30381428 DOI: 10.1523/jneurosci.1665-18.2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/17/2018] [Accepted: 09/20/2018] [Indexed: 12/12/2022] Open
Abstract
How do neurons adapt their endolysosomal system to address the particular challenge of membrane transport across their elaborate cellular landscape and to maintain proteostasis for the lifetime of the organism? Here we review recent findings that address this central question. We discuss the cellular and molecular mechanisms of endolysosomal trafficking and the autophagy pathway in neurons, as well as their role in neuronal development and degeneration. These studies highlight the importance of understanding the basic cell biology of endolysosomal trafficking and autophagy and their roles in the maintenance of proteostasis within the context of neurons, which will be critical for developing effective therapies for various neurodevelopmental and neurodegenerative disorders.
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139
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Abstract
Autophagy is the major cellular pathway to degrade dysfunctional organelles and protein aggregates. Autophagy is particularly important in neurons, which are terminally differentiated cells that must last the lifetime of the organism. There are both constitutive and stress-induced pathways for autophagy in neurons, which catalyze the turnover of aged or damaged mitochondria, endoplasmic reticulum, other cellular organelles, and aggregated proteins. These pathways are required in neurodevelopment as well as in the maintenance of neuronal homeostasis. Here we review the core components of the pathway for autophagosome biogenesis, as well as the cell biology of bulk and selective autophagy in neurons. Finally, we discuss the role of autophagy in neuronal development, homeostasis, and aging and the links between deficits in autophagy and neurodegeneration.
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Affiliation(s)
- Andrea K H Stavoe
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA;
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA;
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140
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Feng F, Zhang M, Yang C, Heng X, Wu X. The dual roles of autophagy in gliomagenesis and clinical therapy strategies based on autophagic regulation mechanisms. Biomed Pharmacother 2019; 120:109441. [PMID: 31541887 DOI: 10.1016/j.biopha.2019.109441] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/02/2019] [Accepted: 09/06/2019] [Indexed: 01/14/2023] Open
Abstract
Autophagy, a self-digestion intracellular catabolic process, plays a crucial role in cellular homeostasis under conditions of starvation, oxidative stress and genotoxic stress. The capability of maintaining homeostasis contributes to preventing malignant behavior in normal cells. Many studies have provided compelling evidence that autophagy is involved in brain tumor recurrence and chemotherapy and radiotherapy resistance. Gliomas, as the primary central nervous system (CNS) tumors, are characterized by rapid, aggressive growth and recurrence and have a poor prognosis and bleak outlook even with modern multimodality strategies involving maximal surgical resection, radiotherapy and alkylating agent-based chemotherapy. Autophagy-associated signaling pathways, such as the extracellular signal-regulated kinase1/2 (ERK1/2) pathway, class I phosphatidylinositol 3-phosphate kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and nuclear factor kappa-B (NF-κB) pathway, act as tumor suppressors or protect tumor cells against chemotherapy/radiotherapy-induced cytotoxicity in gliomagenesis. Through these pathways, both lethal autophagy and protective autophagy play crucial roles in tumor initiation, chemoresistance and glioma stem cell differentiation. Moreover, lethal autophagy and protective autophagy have been identified as novel therapeutic targets in glioma according to the mechanisms described above. Here, we discuss the multiple impacts of the autophagic response on distinct phases of gliomagenesis and the advanced progress of therapies based on this concept.
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Affiliation(s)
- Fan Feng
- Institute of Clinical Medicine College, Qingdao University, # 38, Dengzhou Road, Qingdao 266071, Shandong, China
| | - Moxuan Zhang
- Weifang Medical University, 261042, # 7166, Baotong Western Road, Weifang, Shandong, China
| | - Chuanchao Yang
- Weifang Medical University, 261042, # 7166, Baotong Western Road, Weifang, Shandong, China
| | - Xueyuan Heng
- Department of Neurosurgery, Linyi People's Hospital, # 27, Jiefang Eastern Road, Linyi 276000, Shandong, China.
| | - Xiujie Wu
- Department of Neurosurgery, Linyi People's Hospital, # 27, Jiefang Eastern Road, Linyi 276000, Shandong, China.
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141
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Autophagy Modulation as a Treatment of Amyloid Diseases. Molecules 2019; 24:molecules24183372. [PMID: 31527516 PMCID: PMC6766836 DOI: 10.3390/molecules24183372] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 12/25/2022] Open
Abstract
Amyloids are fibrous proteins aggregated into toxic forms that are implicated in several chronic disorders. More than 30 diseases show deposition of fibrous amyloid proteins associated with cell loss and degeneration in the affected tissues. Evidence demonstrates that amyloid diseases result from protein aggregation or impaired amyloid clearance, but the connection between amyloid accumulation and tissue degeneration is not clear. Common examples of amyloid diseases are Alzheimer's disease (AD), Parkinson's disease (PD) and tauopathies, which are the most common forms of neurodegenerative diseases, as well as polyglutamine disorders and certain peripheral metabolic diseases. In these diseases, increased accumulation of toxic amyloid proteins is suspected to be one of the main causative factors in the disease pathogenesis. It is therefore important to more clearly understand how these toxic amyloid proteins accumulate as this will aide in the development of more effective preventive and therapeutic strategies. Protein homeostasis, or proteostasis, is maintained by multiple cellular pathways-including protein synthesis, quality control, and clearance-which are collectively responsible for preventing protein misfolding or aggregation. Modulating protein degradation is a very complex but attractive treatment strategy used to remove amyloid and improve cell survival. This review will focus on autophagy, an important clearance pathway of amyloid proteins, and strategies for using it as a potential therapeutic target for amyloid diseases. The physiological role of autophagy in cells, pathways for its modulation, its connection with apoptosis, cell models and caveats in developing autophagy as a treatment and as a biomarker is discussed.
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142
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Sequential formation of different layers of dystrophic neurites in Alzheimer's brains. Mol Psychiatry 2019; 24:1369-1382. [PMID: 30899091 PMCID: PMC7204504 DOI: 10.1038/s41380-019-0396-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/08/2019] [Accepted: 02/14/2019] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is characterized by the presence of neuritic plaques in which dystrophic neurites (DNs) are typical constituents. We recently showed that DNs labeled by antibodies to the tubular endoplasmic reticulum (ER) protein reticulon-3 (RTN3) are enriched with clustered tubular ER. However, multi-vesicle bodies are also found in DNs, suggesting that different populations of DNs exist in brains of AD patients. To understand how different DNs evolve to surround core amyloid plaques, we monitored the growth of DNs in AD mouse brains (5xFAD and APP/PS1ΔE9 mice) by multiple approaches, including two-dimensional and three-dimensional (3D) electron microscopy (EM). We discovered that a pre-autophagosome protein ATG9A was enriched in DNs when a plaque was just beginning to develop. ATG9A-positive DNs were often closer to the core amyloid plaque, whereas RTN3 immunoreactive DNs were mostly located in the outer layers of ATG9A-positive DNs. Proteins such as RAB7 and LC3 appeared in DNs at later stages during plaque growth, likely accumulated as a part of large autophagy vesicles, and were distributed relatively furthest from the core amyloid plaque. Reconstructing the 3D structure of different morphologies of DNs revealed that DNs in AD mouse brains were constituted in three layers that are distinct by enriching different types of vesicles, as validated by immune-EM methods. Collectively, our results provide the first evidence that DNs evolve from dysfunctions of pre-autophagosomes, tubular ER, mature autophagosomes, and the ubiquitin proteasome system during plaque growth.
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143
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Liu PP, Xie Y, Meng XY, Kang JS. History and progress of hypotheses and clinical trials for Alzheimer's disease. Signal Transduct Target Ther 2019; 4:29. [PMID: 31637009 PMCID: PMC6799833 DOI: 10.1038/s41392-019-0063-8] [Citation(s) in RCA: 302] [Impact Index Per Article: 60.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 07/07/2019] [Accepted: 07/17/2019] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory loss along with neuropsychiatric symptoms and a decline in activities of daily life. Its main pathological features are cerebral atrophy, amyloid plaques, and neurofibrillary tangles in the brains of patients. There are various descriptive hypotheses regarding the causes of AD, including the cholinergic hypothesis, amyloid hypothesis, tau propagation hypothesis, mitochondrial cascade hypothesis, calcium homeostasis hypothesis, neurovascular hypothesis, inflammatory hypothesis, metal ion hypothesis, and lymphatic system hypothesis. However, the ultimate etiology of AD remains obscure. In this review, we discuss the main hypotheses of AD and related clinical trials. Wealthy puzzles and lessons have made it possible to develop explanatory theories and identify potential strategies for therapeutic interventions for AD. The combination of hypometabolism and autophagy deficiency is likely to be a causative factor for AD. We further propose that fluoxetine, a selective serotonin reuptake inhibitor, has the potential to treat AD.
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Affiliation(s)
- Pei-Pei Liu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 Henan China
| | - Yi Xie
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 Henan China
| | - Xiao-Yan Meng
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 Henan China
| | - Jian-Sheng Kang
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 Henan China
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144
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Park H, Kaang BK. Balanced actions of protein synthesis and degradation in memory formation. ACTA ACUST UNITED AC 2019; 26:299-306. [PMID: 31416903 PMCID: PMC6699412 DOI: 10.1101/lm.048785.118] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/02/2019] [Indexed: 11/24/2022]
Abstract
Storage of long-term memory requires not only protein synthesis but also protein degradation. In this article, we overview recent publications related to this issue, stressing that the balanced actions of protein synthesis and degradation are critical for long-term memory formation. We particularly focused on the brain-derived neurotrophic factor signaling that leads to protein synthesis; proteasome- and autophagy-dependent protein degradation that removes molecular constraints; the role of Fragile X mental retardation protein in translational suppression; and epigenetic modifications that control gene expression at the genomic level. Numerous studies suggest that an imbalance between protein synthesis and degradation leads to intellectual impairment and cognitive disorders.
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Affiliation(s)
- Hyungju Park
- Department of Structure and Function of Neural Network, Korea Brain Research Institute (KBRI), Daegu 41062, South Korea.,Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, South Korea
| | - Bong-Kiun Kaang
- School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
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145
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Zeng J, Martin A, Han X, Shirihai OS, Grinstaff MW. Biodegradable PLGA nanoparticles restore lysosomal acidity and protect neural PC-12 cells against mitochondrial toxicity. Ind Eng Chem Res 2019; 58:13910-13917. [PMID: 38576774 PMCID: PMC10993316 DOI: 10.1021/acs.iecr.9b02003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Exposure of mitochondrial parkinsonian neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+) to PC-12 cells results in significant cell death, decreases lysosomal acidity, and inhibits autophagic flux. Biodegradable poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) of ≈100 nm diameter localize to the lysosome, degrade, and subsequently release their acidic components to acidify the local lysosomal environment. The performance of PLGA NPs with different lysosomal pH modulating capabilities is investigated in PC-12 cells under MPP+ induced mitochondrial toxicity. PLGA NPs perform in a compositional dependent manner, where NPs with a higher glycolic acid to lactic acid ratio content degrade faster, and yield greater degrees of lysosomal pH modulation as well as autophagic flux modulation in PC-12 cells under MPP+ insult. These results show that slight compositional changes of the polymeric NP give rise to differing degrees of lysosomal acidification in PC-12 cells and afford improved cellular degradative activity.
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Affiliation(s)
- Jialiu Zeng
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Andrew Martin
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Xue Han
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Orian S. Shirihai
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90045, United States
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, United States
| | - Mark W. Grinstaff
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, United States
- Department of Chemistry, Boston University, Boston, MA 02215, United States
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146
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Stavoe AKH, Gopal PP, Gubas A, Tooze SA, Holzbaur ELF. Expression of WIPI2B counteracts age-related decline in autophagosome biogenesis in neurons. eLife 2019; 8:e44219. [PMID: 31309927 PMCID: PMC6634969 DOI: 10.7554/elife.44219] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 06/08/2019] [Indexed: 12/15/2022] Open
Abstract
Autophagy defects are implicated in multiple late-onset neurodegenerative diseases including Amyotrophic Lateral Sclerosis (ALS) and Alzheimer's, Huntington's, and Parkinson's diseases. Since aging is the most common shared risk factor in neurodegeneration, we assessed rates of autophagy in mammalian neurons during aging. We identified a significant decrease in the rate of constitutive autophagosome biogenesis during aging and observed pronounced morphological defects in autophagosomes in neurons from aged mice. While early stages of autophagosome formation were unaffected, we detected the frequent production of stalled LC3B-negative isolation membranes in neurons from aged mice. These stalled structures recruited the majority of the autophagy machinery, but failed to develop into LC3B-positive autophagosomes. Importantly, ectopically expressing WIPI2B effectively restored autophagosome biogenesis in aged neurons. This rescue is dependent on the phosphorylation state of WIPI2B at the isolation membrane, suggesting a novel therapeutic target in age-associated neurodegeneration.
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Affiliation(s)
- Andrea KH Stavoe
- Department of PhysiologyPerelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Pallavi P Gopal
- Department of PhysiologyPerelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Andrea Gubas
- Molecular Cell Biology of Autophagy LaboratoryThe Francis Crick InstituteLondonUnited Kingdom
| | - Sharon A Tooze
- Molecular Cell Biology of Autophagy LaboratoryThe Francis Crick InstituteLondonUnited Kingdom
| | - Erika LF Holzbaur
- Department of PhysiologyPerelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
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147
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cPLA2 activation contributes to lysosomal defects leading to impairment of autophagy after spinal cord injury. Cell Death Dis 2019; 10:531. [PMID: 31296844 PMCID: PMC6624263 DOI: 10.1038/s41419-019-1764-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/02/2019] [Accepted: 06/24/2019] [Indexed: 12/19/2022]
Abstract
The autophagy–lysosomal pathway plays an essential role in cellular homeostasis as well as a protective function against a variety of diseases including neurodegeneration. Conversely, inhibition of autophagy, for example due to lysosomal dysfunction, can lead to pathological accumulation of dysfunctional autophagosomes and consequent neuronal cell death. We previously reported that autophagy is inhibited and contributes to neuronal cell death following spinal cord injury (SCI). In this study, we examined lysosomal function and explored the mechanism of lysosomal defects following SCI. Our data demonstrated that expression levels and processing of the lysosomal enzyme cathepsin D (CTSD) are decreased by 2 h after SCI. Enzymatic activity levels of CTSD and another lysosomal enzyme, N-acetyl-alpha-glucosaminidase, are both decreased 24 h post injury, indicating general lysosomal dysfunction. Subcellular fractionation and immunohistochemistry analysis demonstrated that this dysfunction is due to lysosomal membrane permeabilization and leakage of lysosomal contents into the cytosol. To directly assess extent and mechanisms of damage to lysosomal membranes, we performed mass spectrometry-based lipidomic analysis of lysosomes purified from SCI and control spinal cord. At 2 h post injury our data demonstrated increase in several classes of lysosophospholipids, the products of phospholipases (PLAs), as well as accumulation of PLA activators, ceramides. Phospholipase cPLA2, the main PLA species expressed in the CNS, has been previously implicated in mediation of secondary injury after SCI, but the mechanisms of its involvement remain unclear. Our data demonstrate that cPLA2 is activated within 2 h after SCI preferentially in the lysosomal fraction, where it colocalizes with lysosomal-associated membrane protein 2 in neurons. Inhibition of cPLA2 in vivo decreased lysosomal damage, restored autophagy flux, and reduced neuronal cell damage. Taken together our data implicate lysosomal defects in pathophysiology of SCI and for the first time indicate that cPLA2 activation leads to lysosomal damage causing neuronal autophagosome accumulation associated with neuronal cell death.
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148
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Evans CS, Holzbaur ELF. Quality Control in Neurons: Mitophagy and Other Selective Autophagy Mechanisms. J Mol Biol 2019; 432:240-260. [PMID: 31295455 DOI: 10.1016/j.jmb.2019.06.031] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/28/2019] [Accepted: 06/29/2019] [Indexed: 12/19/2022]
Abstract
The cargo-specific removal of organelles via selective autophagy is important to maintain neuronal homeostasis. Genetic studies indicate that deficits in these pathways are implicated in neurodegenerative diseases, including Parkinson's and amyotrophic lateral sclerosis. Here, we review our current understanding of the pathways that regulate mitochondrial quality control, and compare these mechanisms to those regulating turnover of the endoplasmic reticulum and the clearance of protein aggregates. Research suggests that there are multiple mechanisms regulating the degradation of specific cargos, such as dysfunctional organelles and protein aggregates. These mechanisms are critical for neuronal health, as neurons are uniquely vulnerable to impairment in organelle quality control pathways due to their morphology, size, polarity, and postmitotic nature. We highlight the consequences of dysregulation of selective autophagy in neurons and discuss current challenges in correlating noncongruent findings from in vitro and in vivo systems.
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Affiliation(s)
- Chantell S Evans
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6085, USA.
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6085, USA.
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149
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Abstract
Sensitization of the transient receptor potential ion channel vanilloid 1 (TRPV1) is critically involved in inflammatory pain. To date, manifold signaling cascades have been shown to converge onto TRPV1 and enhance its sensitization. However, many of them also play a role for nociceptive pain, which limits their utility as targets for therapeutic intervention. Here, we show that the vesicle transport through interaction with t-SNAREs homolog 1B (Vti1b) protein promotes TRPV1 sensitization upon inflammation in cell culture but leaves normal functioning of TRPV1 intact. Importantly, the effect of Vti1b can be recapitulated in vivo: Virus-mediated knockdown of Vti1b in sensory neurons attenuated thermal hypersensitivity during inflammatory pain without affecting mechanical hypersensitivity or capsaicin-induced nociceptive pain. Interestingly, TRPV1 and Vti1b are localized in close vicinity as indicated by proximity ligation assays and are likely to bind to each other, either directly or indirectly, as suggested by coimmunoprecipitations. Moreover, using a mass spectrometry-based quantitative interactomics approach, we show that Vti1b is less abundant in TRPV1 protein complexes during inflammatory conditions compared with controls. Alongside, we identify numerous novel and pain state-dependent binding partners of native TRPV1 in dorsal root ganglia. These data represent a unique resource on the dynamics of the TRPV1 interactome and facilitate mechanistic insights into TRPV1 regulation. We propose that inflammation-related differences in the TRPV1 interactome identified here could be exploited to specifically target inflammatory pain in the future.
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150
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Lysosome motility and distribution: Relevance in health and disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1076-1087. [DOI: 10.1016/j.bbadis.2019.03.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 12/28/2022]
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