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Karpova A, Aly AAA, Marosi EL, Mikulovic S. Fiber-based in vivo imaging: unveiling avenues for exploring mechanisms of synaptic plasticity and neuronal adaptations underlying behavior. NEUROPHOTONICS 2024; 11:S11507. [PMID: 38390518 PMCID: PMC10883581 DOI: 10.1117/1.nph.11.s1.s11507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/18/2024] [Accepted: 01/23/2024] [Indexed: 02/24/2024]
Abstract
In recent decades, various subfields within neuroscience, spanning molecular, cellular, and systemic dimensions, have significantly advanced our understanding of the elaborate molecular and cellular mechanisms that underpin learning, memory, and adaptive behaviors. There have been notable advancements in imaging techniques, particularly in reaching superficial brain structures. This progress has led to their widespread adoption in numerous laboratories. However, essential physiological and cognitive processes, including sensory integration, emotional modulation of motivated behavior, motor regulation, learning, and memory consolidation, are intricately encoded within deeper brain structures. Hence, visualization techniques such as calcium imaging using miniscopes have gained popularity for studying brain activity in unrestrained animals. Despite its utility, miniscope technology is associated with substantial brain tissue damage caused by gradient refractive index lens implantation. Furthermore, its imaging capabilities are primarily confined to the neuronal somata level, thus constraining a comprehensive exploration of subcellular processes underlying adaptive behaviors. Consequently, the trajectory of neuroscience's future hinges on the development of minimally invasive optical fiber-based endo-microscopes optimized for cellular, subcellular, and molecular imaging within the intricate depths of the brain. In pursuit of this goal, select research groups have invested significant efforts in advancing this technology. In this review, we present a perspective on the potential impact of this innovation on various aspects of neuroscience, enabling the functional exploration of in vivo cellular and subcellular processes that underlie synaptic plasticity and the neuronal adaptations that govern behavior.
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Affiliation(s)
- Anna Karpova
- Leibniz Institute for Neurobiology, RG Neuroplasticity, Magdeburg, Germany
- Otto von Guericke University, Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Ahmed A A Aly
- Leibniz Institute for Neurobiology, RG Neuroplasticity, Magdeburg, Germany
| | - Endre Levente Marosi
- Leibniz Institute for Neurobiology, RG Cognition and Emotion, Magdeburg, Germany
| | - Sanja Mikulovic
- Otto von Guericke University, Center for Behavioral Brain Sciences, Magdeburg, Germany
- Leibniz Institute for Neurobiology, RG Cognition and Emotion, Magdeburg, Germany
- German Centre for Mental Health (DZPG), Magdeburg, Germany
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2
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Lesport E, Commeau L, Genet M, Baulieu EE, Tawk M, Giustiniani J. A decrease in Fkbp52 alters autophagosome maturation and A152T-tau clearance in vivo. Front Cell Neurosci 2024; 18:1425222. [PMID: 39119047 PMCID: PMC11306173 DOI: 10.3389/fncel.2024.1425222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 07/15/2024] [Indexed: 08/10/2024] Open
Abstract
The failure of the autophagy-lysosomal pathway to clear the pathogenic forms of Tau exacerbates the pathogenesis of tauopathies. We have previously shown that the immunophilin FKBP52 interacts both physically and functionally with Tau, and that a decrease in FKBP52 protein levels is associated with Tau deposition in affected human brains. We have also shown that FKBP52 is physiologically present within the lysosomal system in healthy human neurons and that a decrease in FKBP52 expression alters perinuclear lysosomal positioning and Tau clearance during Tau-induced proteotoxic stress in vitro. In this study, we generate a zebrafish fkbp4 loss of function mutant and show that axonal retrograde trafficking of Lamp1 vesicles is altered in this mutant. Moreover, using our transgenic HuC::mCherry-EGFP-LC3 line, we demonstrate that the autophagic flux is impaired in fkbp4 mutant embryos, suggesting a role for Fkbp52 in the maturation of autophagic vesicles. Alterations in both axonal transport and autophagic flux are more evident in heterozygous rather than homozygous fkbp4 mutants. Finally, taking advantage of the previously described A152T-Tau transgenic fish, we show that the clearance of pathogenic A152T-Tau mutant proteins is slower in fkbp4 +/- mutants in comparison to fkbp4 +/+ larvae. Altogether, these results indicate that Fkbp52 is required for the normal trafficking and maturation of lysosomes and autophagic vacuoles along axons, and that its decrease is sufficient to hinder the clearance of pathogenic Tau in vivo.
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Affiliation(s)
- Emilie Lesport
- Institut Professeur Baulieu, INSERM U1195, Kremlin-Bicêtre, France
- INSERM U1195, Université Paris-Saclay, Kremlin-Bicêtre, France
| | - Lucie Commeau
- Institut Professeur Baulieu, INSERM U1195, Kremlin-Bicêtre, France
| | - Mélanie Genet
- Institut Professeur Baulieu, INSERM U1195, Kremlin-Bicêtre, France
| | - Etienne-Emile Baulieu
- Institut Professeur Baulieu, INSERM U1195, Kremlin-Bicêtre, France
- INSERM U1195, Université Paris-Saclay, Kremlin-Bicêtre, France
| | - Marcel Tawk
- INSERM U1195, Université Paris-Saclay, Kremlin-Bicêtre, France
| | - Julien Giustiniani
- Institut Professeur Baulieu, INSERM U1195, Kremlin-Bicêtre, France
- INSERM U1195, Université Paris-Saclay, Kremlin-Bicêtre, France
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3
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Dou D, Aiken J, Holzbaur EL. RAB3 phosphorylation by pathogenic LRRK2 impairs trafficking of synaptic vesicle precursors. J Cell Biol 2024; 223:e202307092. [PMID: 38512027 PMCID: PMC10959120 DOI: 10.1083/jcb.202307092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 02/01/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
Gain-of-function mutations in the LRRK2 gene cause Parkinson's disease (PD), characterized by debilitating motor and non-motor symptoms. Increased phosphorylation of a subset of RAB GTPases by LRRK2 is implicated in PD pathogenesis. We find that increased phosphorylation of RAB3A, a cardinal synaptic vesicle precursor (SVP) protein, disrupts anterograde axonal transport of SVPs in iPSC-derived human neurons (iNeurons) expressing hyperactive LRRK2-p.R1441H. Knockout of the opposing protein phosphatase 1H (PPM1H) in iNeurons phenocopies this effect. In these models, the compartmental distribution of synaptic proteins is altered; synaptophysin and synaptobrevin-2 become sequestered in the neuronal soma with decreased delivery to presynaptic sites along the axon. We find that RAB3A phosphorylation disrupts binding to the motor adaptor MADD, potentially preventing the formation of the RAB3A-MADD-KIF1A/1Bβ complex driving anterograde SVP transport. RAB3A hyperphosphorylation also disrupts interactions with RAB3GAP and RAB-GDI1. Our results reveal a mechanism by which pathogenic hyperactive LRRK2 may contribute to the altered synaptic homeostasis associated with characteristic non-motor and cognitive manifestations of PD.
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Affiliation(s)
- Dan Dou
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Erika L.F. Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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4
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De Pace R, Ghosh S, Ryan VH, Sohn M, Jarnik M, Rezvan Sangsari P, Morgan NY, Dale RK, Ward ME, Bonifacino JS. Messenger RNA transport on lysosomal vesicles maintains axonal mitochondrial homeostasis and prevents axonal degeneration. Nat Neurosci 2024; 27:1087-1102. [PMID: 38600167 PMCID: PMC11156585 DOI: 10.1038/s41593-024-01619-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 03/07/2024] [Indexed: 04/12/2024]
Abstract
In neurons, RNA granules are transported along the axon for local translation away from the soma. Recent studies indicate that some of this transport involves hitchhiking of RNA granules on lysosome-related vesicles. In the present study, we leveraged the ability to prevent transport of these vesicles into the axon by knockout of the lysosome-kinesin adaptor BLOC-one-related complex (BORC) to identify a subset of axonal mRNAs that depend on lysosome-related vesicles for transport. We found that BORC knockout causes depletion of a large group of axonal mRNAs mainly encoding ribosomal and mitochondrial/oxidative phosphorylation proteins. This depletion results in mitochondrial defects and eventually leads to axonal degeneration in human induced pluripotent stem cell (iPSC)-derived and mouse neurons. Pathway analyses of the depleted mRNAs revealed a mechanistic connection of BORC deficiency with common neurodegenerative disorders. These results demonstrate that mRNA transport on lysosome-related vesicles is critical for the maintenance of axonal homeostasis and that its failure causes axonal degeneration.
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Affiliation(s)
- Raffaella De Pace
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Saikat Ghosh
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Veronica H Ryan
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Mira Sohn
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Paniz Rezvan Sangsari
- Biomedical Engineering and Physical Science Shared Resource, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Nicole Y Morgan
- Biomedical Engineering and Physical Science Shared Resource, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Ryan K Dale
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michael E Ward
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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5
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Fellows AD, Bruntraeger M, Burgold T, Bassett AR, Carter AP. Dynein and dynactin move long-range but are delivered separately to the axon tip. J Cell Biol 2024; 223:e202309084. [PMID: 38407313 PMCID: PMC10896695 DOI: 10.1083/jcb.202309084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/17/2024] [Accepted: 02/05/2024] [Indexed: 02/27/2024] Open
Abstract
Axonal transport is essential for neuronal survival. This is driven by microtubule motors including dynein, which transports cargo from the axon tip back to the cell body. This function requires its cofactor dynactin and regulators LIS1 and NDEL1. Due to difficulties imaging dynein at a single-molecule level, it is unclear how this motor and its regulators coordinate transport along the length of the axon. Here, we use a neuron-inducible human stem cell line (NGN2-OPTi-OX) to endogenously tag dynein components and visualize them at a near-single molecule regime. In the retrograde direction, we find that dynein and dynactin can move the entire length of the axon (>500 µm). Furthermore, LIS1 and NDEL1 also undergo long-distance movement, despite being mainly implicated with the initiation of dynein transport. Intriguingly, in the anterograde direction, dynein/LIS1 moves faster than dynactin/NDEL1, consistent with transport on different cargos. Therefore, neurons ensure efficient transport by holding dynein/dynactin on cargos over long distances but keeping them separate until required.
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Affiliation(s)
- Alexander D Fellows
- Division of Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | | | - Thomas Burgold
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
| | | | - Andrew P Carter
- Division of Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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6
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Aiken J, Holzbaur ELF. Spastin locally amplifies microtubule dynamics to pattern the axon for presynaptic cargo delivery. Curr Biol 2024; 34:1687-1704.e8. [PMID: 38554708 PMCID: PMC11042977 DOI: 10.1016/j.cub.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/10/2024] [Accepted: 03/08/2024] [Indexed: 04/02/2024]
Abstract
Neurons rely on the long-range trafficking of synaptic components to form and maintain the complex neural networks that encode the human experience. With a single neuron capable of forming thousands of distinct en passant synapses along its axon, spatially precise delivery of the necessary synaptic components is paramount. How these synapses are patterned, as well as how the efficient delivery of synaptic components is regulated, remains largely unknown. Here, we reveal a novel role for the microtubule (MT)-severing enzyme spastin in locally enhancing MT polymerization to influence presynaptic cargo pausing and retention along the axon. In human neurons derived from induced pluripotent stem cells (iPSCs), we identify sites stably enriched for presynaptic components along the axon prior to the robust assembly of mature presynapses apposed by postsynaptic contacts. These sites are capable of cycling synaptic vesicles, are enriched with spastin, and are hotspots for new MT growth and synaptic vesicle precursor (SVP) pausing/retention. The disruption of neuronal spastin level or activity, by CRISPRi-mediated depletion, transient overexpression, or pharmacologic inhibition of enzymatic activity, interrupts the localized enrichment of dynamic MT plus ends and diminishes SVP accumulation. Using an innovative human heterologous synapse model, where microfluidically isolated human axons recognize and form presynaptic connections with neuroligin-expressing non-neuronal cells, we reveal that neurons deficient for spastin do not achieve the same level of presynaptic component accumulation as control neurons. We propose a model where spastin acts locally as an amplifier of MT polymerization to pattern specific regions of the axon for synaptogenesis and guide synaptic cargo delivery.
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Affiliation(s)
- Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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7
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Caracci MO, Pizarro H, Alarcón-Godoy C, Fuentealba LM, Farfán P, De Pace R, Santibañez N, Cavieres VA, Pástor TP, Bonifacino JS, Mardones GA, Marzolo MP. The Reelin receptor ApoER2 is a cargo for the adaptor protein complex AP-4: Implications for Hereditary Spastic Paraplegia. Prog Neurobiol 2024; 234:102575. [PMID: 38281682 PMCID: PMC10979513 DOI: 10.1016/j.pneurobio.2024.102575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 01/11/2024] [Accepted: 01/23/2024] [Indexed: 01/30/2024]
Abstract
Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes export of selected cargo proteins from the trans-Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the µ4 (AP4M1) subunit of AP-4. AP4E1- knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1-KO mice display increased co-localization of ApoER2 with Golgi markers. Furthermore, hippocampal neurons from Ap4e1-KO mice and AP4M1-KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post-Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild-type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. This work thus establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.
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Affiliation(s)
- Mario O Caracci
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Héctor Pizarro
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Carlos Alarcón-Godoy
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Luz M Fuentealba
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Pamela Farfán
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Raffaella De Pace
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Natacha Santibañez
- Instituto de Patología Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Viviana A Cavieres
- Departamento de Ciencias Biológicas y Químicas, Fac. Med y Ciencia, USS, Santiago, Chile
| | - Tammy P Pástor
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Gonzalo A Mardones
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile
| | - María-Paz Marzolo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile.
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8
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Caracci MO, Pizarro H, Alarcón-Godoy C, Fuentealba LM, Farfán P, Pace RD, Santibañez N, Cavieres VA, Pástor TP, Bonifacino JS, Mardones GA, Marzolo MP. The Reelin Receptor ApoER2 is a Cargo for the Adaptor Protein Complex AP-4: Implications for Hereditary Spastic Paraplegia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.21.572896. [PMID: 38187774 PMCID: PMC10769347 DOI: 10.1101/2023.12.21.572896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes protein export from the trans -Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the µ4 (AP4M1) subunit of AP-4. AP4E1 -knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1 -KO mice display increased Golgi localization of ApoER2. Furthermore, hippocampal neurons from Ap4e1 -KO mice and AP4M1 -KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post-Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild-type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. Altogether, this work establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.
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9
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Meydan S, Guydosh NR. Is there a localized role for translational quality control? RNA (NEW YORK, N.Y.) 2023; 29:1623-1643. [PMID: 37582617 PMCID: PMC10578494 DOI: 10.1261/rna.079683.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023]
Abstract
It is known that mRNAs and the machinery that translates them are not uniformly distributed throughout the cytoplasm. As a result, the expression of some genes is localized to particular parts of the cell and this makes it possible to carry out important activities, such as growth and signaling, in three-dimensional space. However, the functions of localized gene expression are not fully understood, and the underlying mechanisms that enable localized expression have not been determined in many cases. One consideration that could help in addressing these challenges is the role of quality control (QC) mechanisms that monitor translating ribosomes. On a global level, QC pathways are critical for detecting aberrant translation events, such as a ribosome that stalls while translating, and responding by activating stress pathways and resolving problematic ribosomes and mRNAs at the molecular level. However, it is unclear how these pathways, even when uniformly active throughout the cell, affect local translation. Importantly, some QC pathways have themselves been reported to be enriched in the proximity of particular organelles, but the extent of such localized activity remains largely unknown. Here, we describe the major QC pathways and review studies that have begun to explore their roles in localized translation. Given the limited data in this area, we also pose broad questions about the possibilities and limitations for how QC pathways could facilitate localized gene expression in the cell with the goal of offering ideas for future experimentation.
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Affiliation(s)
- Sezen Meydan
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nicholas R Guydosh
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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10
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Menduti G, Boido M. Recent Advances in High-Content Imaging and Analysis in iPSC-Based Modelling of Neurodegenerative Diseases. Int J Mol Sci 2023; 24:14689. [PMID: 37834135 PMCID: PMC10572296 DOI: 10.3390/ijms241914689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/24/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
In the field of neurodegenerative pathologies, the platforms for disease modelling based on patient-derived induced pluripotent stem cells (iPSCs) represent a valuable molecular diagnostic/prognostic tool. Indeed, they paved the way for the in vitro recapitulation of the pathological mechanisms underlying neurodegeneration and for characterizing the molecular heterogeneity of disease manifestations, also enabling drug screening approaches for new therapeutic candidates. A major challenge is related to the choice and optimization of the morpho-functional study designs in human iPSC-derived neurons to deeply detail the cell phenotypes as markers of neurodegeneration. In recent years, the specific combination of high-throughput screening with subcellular resolution microscopy for cell-based high-content imaging (HCI) screening allowed in-depth analyses of cell morphology and neurite trafficking in iPSC-derived neuronal cells by using specific cutting-edge microscopes and automated computational assays. The present work aims to describe the main recent protocols and advances achieved with the HCI analysis in iPSC-based modelling of neurodegenerative diseases, highlighting technical and bioinformatics tips and tricks for further uses and research. To this end, microscopy requirements and the latest computational pipelines to analyze imaging data will be explored, while also providing an overview of the available open-source high-throughput automated platforms.
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Affiliation(s)
- Giovanna Menduti
- Department of Neuroscience “Rita Levi Montalcini”, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Regione Gonzole 10, Orbassano, 10043 Turin, TO, Italy;
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11
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Mulligan RJ, Winckler B. Regulation of Endosomal Trafficking by Rab7 and Its Effectors in Neurons: Clues from Charcot-Marie-Tooth 2B Disease. Biomolecules 2023; 13:1399. [PMID: 37759799 PMCID: PMC10527268 DOI: 10.3390/biom13091399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Intracellular endosomal trafficking controls the balance between protein degradation and synthesis, i.e., proteostasis, but also many of the cellular signaling pathways that emanate from activated growth factor receptors after endocytosis. Endosomal trafficking, sorting, and motility are coordinated by the activity of small GTPases, including Rab proteins, whose function as molecular switches direct activity at endosomal membranes through effector proteins. Rab7 is particularly important in the coordination of the degradative functions of the pathway. Rab7 effectors control endosomal maturation and the properties of late endosomal and lysosomal compartments, such as coordination of recycling, motility, and fusion with downstream compartments. The spatiotemporal regulation of endosomal receptor trafficking is particularly challenging in neurons because of their enormous size, their distinct intracellular domains with unique requirements (dendrites vs. axons), and their long lifespans as postmitotic, differentiated cells. In Charcot-Marie-Tooth 2B disease (CMT2B), familial missense mutations in Rab7 cause alterations in GTPase cycling and trafficking, leading to an ulcero-mutilating peripheral neuropathy. The prevailing hypothesis to account for CMT2B pathologies is that CMT2B-associated Rab7 alleles alter endocytic trafficking of the neurotrophin NGF and its receptor TrkA and, thereby, disrupt normal trophic signaling in the peripheral nervous system, but other Rab7-dependent pathways are also impacted. Here, using TrkA as a prototypical endocytic cargo, we review physiologic Rab7 effector interactions and control in neurons. Since neurons are among the largest cells in the body, we place particular emphasis on the temporal and spatial regulation of endosomal sorting and trafficking in neuronal processes. We further discuss the current findings in CMT2B mutant Rab7 models, the impact of mutations on effector interactions or balance, and how this dysregulation may confer disease.
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Affiliation(s)
- Ryan J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
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12
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Aiken J, Holzbaur ELF. Spastin locally amplifies microtubule dynamics to pattern the axon for presynaptic cargo delivery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.08.552320. [PMID: 37609249 PMCID: PMC10441300 DOI: 10.1101/2023.08.08.552320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Neurons rely on long-range trafficking of synaptic components to form and maintain the complex neural networks that encode the human experience. With a single neuron capable of forming thousands of distinct en passant synapses along its axon, spatially precise delivery of the necessary synaptic components is paramount. How these synapses are patterned, and how efficient delivery of synaptic components is regulated, remains largely unknown. Here, we reveal a novel role for the microtubule severing enzyme spastin in locally enhancing microtubule polymerization to influence presynaptic cargo pausing and retention along the axon. In human neurons derived from induced pluripotent stem cells (iPSCs), we identify sites stably enriched for presynaptic components, termed 'protosynapses', which are distributed along the axon prior to the robust assembly of mature presynapses apposed by postsynaptic contacts. These sites are capable of cycling synaptic vesicles, are enriched with spastin, and are hotspots for new microtubule growth and synaptic vesicle precursor (SVP) pausing/retention. Disruption of neuronal spastin, either by CRISPRi-mediated depletion or transient overexpression, interrupts the localized enrichment of dynamic microtubule plus ends and diminishes SVP accumulation. Using an innovative human heterologous synapse model, where microfluidically isolated human axons recognize and form presynaptic connections with neuroligin-expressing non-neuronal cells, we reveal that neurons deficient for spastin do not achieve the same level of presynaptic component accumulation as control neurons. We propose a model where spastin acts locally as an amplifier of microtubule polymerization to pattern specific regions of the axon for synaptogenesis and guide synaptic cargo delivery.
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Affiliation(s)
- Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Dou D, Aiken J, Holzbaur EL. RAB3 phosphorylation by pathogenic LRRK2 impairs trafficking of synaptic vesicle precursors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550521. [PMID: 37546777 PMCID: PMC10402060 DOI: 10.1101/2023.07.25.550521] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Gain-of-function mutations in the LRRK2 gene cause Parkinson's disease (PD), characterized by debilitating motor and non-motor symptoms. Increased phosphorylation of a subset of RAB GTPases by LRRK2 is implicated in PD pathogenesis. We find that increased phosphorylation of RAB3A, a cardinal synaptic vesicle precursor (SVP) protein, disrupts anterograde axonal transport of SVPs in iPSC-derived human neurons (iNeurons) expressing hyperactive LRRK2-p.R1441H. Knockout of the opposing protein phosphatase 1H (PPM1H) in iNeurons phenocopies this effect. In these models, the compartmental distribution of synaptic proteins is altered; synaptophysin and synaptobrevin-2 become sequestered in the neuronal soma with decreased delivery to presynaptic sites along the axon. We find that RAB3A phosphorylation disrupts binding to the motor adapter MADD, potentially preventing formation of the RAB3A-MADD-KIF1A/1Bβ complex driving anterograde SVP transport. RAB3A hyperphosphorylation also disrupts interactions with RAB3GAP and RAB-GDI1. Our results reveal a mechanism by which pathogenic hyperactive LRRK2 may contribute to the altered synaptic homeostasis associated with characteristic non-motor and cognitive manifestations of PD.
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Affiliation(s)
- Dan Dou
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L.F. Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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14
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Wang J, Daniszewski M, Hao MM, Hernández D, Pébay A, Gleeson PA, Fourriere L. Organelle mapping in dendrites of human iPSC-derived neurons reveals dynamic functional dendritic Golgi structures. Cell Rep 2023; 42:112709. [PMID: 37393622 DOI: 10.1016/j.celrep.2023.112709] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/15/2023] [Accepted: 06/12/2023] [Indexed: 07/04/2023] Open
Abstract
Secretory pathways within dendrites of neurons have been proposed for local transport of newly synthesized proteins. However, little is known about the dynamics of the local secretory system and whether the organelles are transient or stable structures. Here, we quantify the spatial and dynamic behavior of dendritic Golgi and endosomes during differentiation of human neurons generated from induced pluripotent stem cells (iPSCs). In early neuronal development, before and during migration, the entire Golgi apparatus transiently translocates from the soma into dendrites. In mature neurons, dynamic Golgi elements, containing cis and trans cisternae, are transported from the soma along dendrites, in an actin-dependent process. Dendritic Golgi outposts are dynamic and display bidirectional movement. Similar structures were observed in cerebral organoids. Using the retention using selective hooks (RUSH) system, Golgi resident proteins are transported efficiently into Golgi outposts from the endoplasmic reticulum. This study reveals dynamic, functional Golgi structures in dendrites and a spatial map for investigating dendrite trafficking in human neurons.
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Affiliation(s)
- Jingqi Wang
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Maciej Daniszewski
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Marlene M Hao
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Damián Hernández
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Alice Pébay
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC 3010, Australia; Department of Surgery, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Paul A Gleeson
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia.
| | - Lou Fourriere
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia.
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15
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Dou D, Smith EM, Evans CS, Boecker CA, Holzbaur ELF. Regulatory imbalance between LRRK2 kinase, PPM1H phosphatase, and ARF6 GTPase disrupts the axonal transport of autophagosomes. Cell Rep 2023; 42:112448. [PMID: 37133994 PMCID: PMC10304398 DOI: 10.1016/j.celrep.2023.112448] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 03/15/2023] [Accepted: 04/13/2023] [Indexed: 05/04/2023] Open
Abstract
Gain-of-function mutations in the LRRK2 gene cause Parkinson's disease (PD), increasing phosphorylation of RAB GTPases through hyperactive kinase activity. We find that LRRK2-hyperphosphorylated RABs disrupt the axonal transport of autophagosomes by perturbing the coordinated regulation of cytoplasmic dynein and kinesin. In iPSC-derived human neurons, knockin of the strongly hyperactive LRRK2-p.R1441H mutation causes striking impairments in autophagosome transport, inducing frequent directional reversals and pauses. Knockout of the opposing protein phosphatase 1H (PPM1H) phenocopies the effect of hyperactive LRRK2. Overexpression of ADP-ribosylation factor 6 (ARF6), a GTPase that acts as a switch for selective activation of dynein or kinesin, attenuates transport defects in both p.R1441H knockin and PPM1H knockout neurons. Together, these findings support a model where a regulatory imbalance between LRRK2-hyperphosphorylated RABs and ARF6 induces an unproductive "tug-of-war" between dynein and kinesin, disrupting processive autophagosome transport. This disruption may contribute to PD pathogenesis by impairing the essential homeostatic functions of axonal autophagy.
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Affiliation(s)
- Dan Dou
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA; Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Erin M Smith
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chantell S Evans
- Duke University Medical Center, Duke University, Durham, NC 27710, USA
| | - C Alexander Boecker
- Department of Neurology, University Medical Center Goettingen, 37077 Goettingen, Germany.
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA; Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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16
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Digilio L, McMahon LP, Duston A, Yap CC, Winckler B. Quantifying Single and Dual Channel Live Imaging Data: Kymograph Analysis of Organelle Motility in Neurons. Bio Protoc 2023; 13:e4675. [PMID: 37251096 PMCID: PMC10213073 DOI: 10.21769/bioprotoc.4675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/06/2023] [Accepted: 03/21/2023] [Indexed: 05/31/2023] Open
Abstract
Live imaging is commonly used to study dynamic processes in cells. Many labs carrying out live imaging in neurons use kymographs as a tool. Kymographs display time-dependent microscope data (time-lapsed images) in two-dimensional representations showing position vs. time. Extraction of quantitative data from kymographs, often done manually, is time-consuming and not standardized across labs. We describe here our recent methodology for quantitatively analyzing single color kymographs. We discuss the challenges and solutions of reliably extracting quantifiable data from single-channel kymographs. When acquiring in two fluorescent channels, the challenge becomes analyzing two objects that may co-traffic together. One must carefully examine the kymographs from both channels and decide which tracks are the same or try to identify the coincident tracks from an overlay of the two channels. This process is laborious and time consuming. The difficulty in finding an available tool for such analysis has led us to create a program to do so, called KymoMerge. KymoMerge semi-automates the process of identifying co-located tracks in multi-channel kymographs and produces a co-localized output kymograph that can be analyzed further. We describe our analysis, caveats, and challenges of two-color imaging using KymoMerge.
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Affiliation(s)
- Laura Digilio
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Lloyd P. McMahon
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Alois Duston
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Chan Choo Yap
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
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Gallagher ER, Holzbaur ELF. The selective autophagy adaptor p62/SQSTM1 forms phase condensates regulated by HSP27 that facilitate the clearance of damaged lysosomes via lysophagy. Cell Rep 2023; 42:112037. [PMID: 36701233 PMCID: PMC10366342 DOI: 10.1016/j.celrep.2023.112037] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 12/16/2022] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
In response to lysosomal damage, cells engage several quality-control mechanisms, including the selective isolation and degradation of damaged lysosomes by lysophagy. Here, we report that the selective autophagy adaptor SQSTM1/p62 is recruited to damaged lysosomes in both HeLa cells and neurons and is required for lysophagic flux. The Phox and Bem1p (PB1) domain of p62 mediates oligomerization and is specifically required for lysophagy. Consistent with this observation, we find that p62 forms condensates on damaged lysosomes. These condensates are precisely tuned by the small heat shock protein HSP27, which is phosphorylated in response to lysosomal injury and maintains the liquidity of p62 condensates, facilitating autophagosome formation. Mutations in p62 have been identified in patients with amyotrophic lateral sclerosis (ALS); ALS-associated mutations in p62 impair lysophagy, suggesting that deficits in this pathway may contribute to neurodegeneration. Thus, p62 condensates regulated by HSP27 promote lysophagy by forming platforms for autophagosome biogenesis at damaged lysosomes.
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Affiliation(s)
- Elizabeth R Gallagher
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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18
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Cason SE, Mogre SS, Holzbaur ELF, Koslover EF. Spatiotemporal analysis of axonal autophagosome-lysosome dynamics reveals limited fusion events and slow maturation. Mol Biol Cell 2022; 33:ar123. [PMID: 36044338 PMCID: PMC9634976 DOI: 10.1091/mbc.e22-03-0111] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Macroautophagy is a homeostatic process required to clear cellular waste. Neuronal autophagosomes form constitutively in the distal tip of the axon and are actively transported toward the soma, with cargo degradation initiated en route. Cargo turnover requires autophagosomes to fuse with lysosomes to acquire degradative enzymes; however, directly imaging these fusion events in the axon is impractical. Here we use a quantitative model, parameterized and validated using data from primary hippocampal neurons, to explore the autophagosome maturation process. We demonstrate that retrograde autophagosome motility is independent of fusion and that most autophagosomes fuse with only a few lysosomes during axonal transport. Our results indicate that breakdown of the inner autophagosomal membrane is much slower in neurons than in nonneuronal cell types, highlighting the importance of this late maturation step. Together, rigorous quantitative measurements and mathematical modeling elucidate the dynamics of autophagosome-lysosome interaction and autophagosomal maturation in the axon.
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Affiliation(s)
- Sydney E. Cason
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104
| | - Saurabh S. Mogre
- Department of Physics, University of California, San Diego, La Jolla, CA 92093
| | | | - Elena F. Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA 92093,*Address correspondence to: Elena F. Koslover ()
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19
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Yap CC, Mason AJ, Winckler B. Dynamics and distribution of endosomes and lysosomes in dendrites. Curr Opin Neurobiol 2022; 74:102537. [DOI: 10.1016/j.conb.2022.102537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 02/16/2022] [Accepted: 03/06/2022] [Indexed: 11/03/2022]
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Yap CC, Winckler B. Spatial regulation of endosomes in growing dendrites. Dev Biol 2022; 486:5-14. [PMID: 35306006 PMCID: PMC10646839 DOI: 10.1016/j.ydbio.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 02/21/2022] [Accepted: 03/13/2022] [Indexed: 01/19/2023]
Abstract
Many membrane proteins are highly enriched in either dendrites or axons. This non-uniform distribution is a critical feature of neuronal polarity and underlies neuronal function. The molecular mechanisms responsible for polarized distribution of membrane proteins has been studied for some time and many answers have emerged. A less well studied feature of neurons is that organelles are also frequently non-uniformly distributed. For instance, EEA1-positive early endosomes are somatodendritic whereas synaptic vesicles are axonal. In addition, some organelles are present in both axons and dendrites, but not distributed uniformly along the processes. One well known example are lysosomes which are abundant in the soma and proximal dendrite, but sparse in the distal dendrite and the distal axon. The mechanisms that determine the spatial distribution of organelles along dendrites are only starting to be studied. In this review, we will discuss the cell biological mechanisms of how the distribution of diverse sets of endosomes along the proximal-distal axis of dendrites might be regulated. In particular, we will focus on the regulation of bulk homeostatic mechanisms as opposed to local regulation. We posit that immature dendrites regulate organelle motility differently from mature dendrites in order to spatially organize dendrite growth, branching and sculpting.
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21
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Yap CC, Digilio L, McMahon LP, Wang T, Winckler B. Dynein Is Required for Rab7-Dependent Endosome Maturation, Retrograde Dendritic Transport, and Degradation. J Neurosci 2022; 42:4415-4434. [PMID: 35474277 PMCID: PMC9172292 DOI: 10.1523/jneurosci.2530-21.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 03/30/2022] [Accepted: 04/15/2022] [Indexed: 11/21/2022] Open
Abstract
In all cell types, endocytosed cargo is transported along a set of endosomal compartments, which are linked maturationally from early endosomes (EEs) via late endosomes (LEs) to lysosomes. Lysosomes are critical for degradation of proteins that enter through endocytic as well as autophagic pathways. Rab7 is the master regulator of early-to-late endosome maturation, motility, and fusion with lysosomes. We previously showed that most degradative lysosomes are localized in the soma and in the first 25 µm of the dendrite and that bulk degradation of dendritic membrane proteins occurs in/near the soma. Dendritic late endosomes therefore move retrogradely in a Rab7-dependent manner for fusion with somatic lysosomes. We now used cultured E18 rat hippocampal neurons of both sexes to determine which microtubule motor is responsible for degradative flux of late endosomes. Based on multiple approaches (inhibiting dynein/dynactin itself or inhibiting dynein recruitment to endosomes by expressing the C-terminus of the Rab7 effector, RILP), we now demonstrate that net retrograde flux of late endosomes in dendrites is supported by dynein. Inhibition of dynein also delays maturation of somatic endosomes, as evidenced by excessive accumulation of Rab7. In addition, degradation of dendritic cargos is inhibited. Our results also suggest that GDP-GTP cycling of Rab7 appears necessary not only for endosomal maturation but also for fusion with lysosomes subsequent to arrival in the soma. In conclusion, Rab7-dependent dynein/dynactin recruitment to dendritic endosomes plays multifaceted roles in dendritic endosome maturation as well as retrograde transport of late endosomes to sustain normal degradative flux.SIGNIFICANCE STATEMENT Lysosomes are critical for degradation of membrane and extracellular proteins that enter through endocytosis. Lysosomes are also the endpoint of autophagy and thus responsible for protein and organelle homeostasis. Endosomal-lysosomal dysfunction is linked to neurodegeneration and aging. We identify roles in dendrites for two proteins with links to human diseases, Rab7 and dynein. Our previous work identified a process that requires directional retrograde transport in dendrites, namely, efficient degradation of short-lived membrane proteins. Based on multiple approaches, we demonstrate that Rab7-dependent recruitment of dynein motors supports net retrograde transport to lysosomes and is needed for endosome maturation. Our data also suggest that GDP-GTP cycling of Rab7 is required for fusion with lysosomes and degradation, subsequent to arrival in the soma.
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Affiliation(s)
- Chan Choo Yap
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
| | - Laura Digilio
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
| | - Lloyd P McMahon
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
| | - Tuanlao Wang
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian Province 361005, China
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
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22
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Barral DC, Staiano L, Guimas Almeida C, Cutler DF, Eden ER, Futter CE, Galione A, Marques ARA, Medina DL, Napolitano G, Settembre C, Vieira OV, Aerts JMFG, Atakpa‐Adaji P, Bruno G, Capuozzo A, De Leonibus E, Di Malta C, Escrevente C, Esposito A, Grumati P, Hall MJ, Teodoro RO, Lopes SS, Luzio JP, Monfregola J, Montefusco S, Platt FM, Polishchuck R, De Risi M, Sambri I, Soldati C, Seabra MC. Current methods to analyze lysosome morphology, positioning, motility and function. Traffic 2022; 23:238-269. [PMID: 35343629 PMCID: PMC9323414 DOI: 10.1111/tra.12839] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 01/09/2023]
Abstract
Since the discovery of lysosomes more than 70 years ago, much has been learned about the functions of these organelles. Lysosomes were regarded as exclusively degradative organelles, but more recent research has shown that they play essential roles in several other cellular functions, such as nutrient sensing, intracellular signalling and metabolism. Methodological advances played a key part in generating our current knowledge about the biology of this multifaceted organelle. In this review, we cover current methods used to analyze lysosome morphology, positioning, motility and function. We highlight the principles behind these methods, the methodological strategies and their advantages and limitations. To extract accurate information and avoid misinterpretations, we discuss the best strategies to identify lysosomes and assess their characteristics and functions. With this review, we aim to stimulate an increase in the quantity and quality of research on lysosomes and further ground-breaking discoveries on an organelle that continues to surprise and excite cell biologists.
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Affiliation(s)
- Duarte C. Barral
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
| | - Leopoldo Staiano
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Institute for Genetic and Biomedical ResearchNational Research Council (CNR)MilanItaly
| | | | - Dan F. Cutler
- MRC Laboratory for Molecular Cell BiologyUniversity College LondonLondonUK
| | - Emily R. Eden
- University College London (UCL) Institute of OphthalmologyLondonUK
| | - Clare E. Futter
- University College London (UCL) Institute of OphthalmologyLondonUK
| | | | | | - Diego Luis Medina
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Medical Genetics Unit, Department of Medical and Translational ScienceFederico II UniversityNaplesItaly
| | - Gennaro Napolitano
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Medical Genetics Unit, Department of Medical and Translational ScienceFederico II UniversityNaplesItaly
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Clinical Medicine and Surgery DepartmentFederico II UniversityNaplesItaly
| | - Otília V. Vieira
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
| | | | | | - Gemma Bruno
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | | | - Elvira De Leonibus
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Institute of Biochemistry and Cell Biology, CNRRomeItaly
| | - Chiara Di Malta
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Medical Genetics Unit, Department of Medical and Translational ScienceFederico II UniversityNaplesItaly
| | | | | | - Paolo Grumati
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | - Michael J. Hall
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
| | - Rita O. Teodoro
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
| | - Susana S. Lopes
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
| | - J. Paul Luzio
- Cambridge Institute for Medical ResearchUniversity of CambridgeCambridgeUK
| | | | | | | | | | - Maria De Risi
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | - Irene Sambri
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Medical Genetics Unit, Department of Medical and Translational ScienceFederico II UniversityNaplesItaly
| | - Chiara Soldati
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | - Miguel C. Seabra
- CEDOC, NOVA Medical School, NMS, Universidade NOVA de LisboaLisbonPortugal
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23
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Nassal JP, Murphy FH, Toonen RF, Verhage M. Differential axonal trafficking of Neuropeptide Y-, LAMP1-, and RAB7-tagged organelles in vivo. eLife 2022; 11:81721. [PMID: 36459486 PMCID: PMC9718525 DOI: 10.7554/elife.81721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/22/2022] [Indexed: 12/04/2022] Open
Abstract
Different organelles traveling through neurons exhibit distinct properties in vitro, but this has not been investigated in the intact mammalian brain. We established simultaneous dual color two-photon microscopy to visualize the trafficking of Neuropeptide Y (NPY)-, LAMP1-, and RAB7-tagged organelles in thalamocortical axons imaged in mouse cortex in vivo. This revealed that LAMP1- and RAB7-tagged organelles move significantly faster than NPY-tagged organelles in both anterograde and retrograde direction. NPY traveled more selectively in anterograde direction than LAMP1 and RAB7. By using a synapse marker and a calcium sensor, we further investigated the transport dynamics of NPY-tagged organelles. We found that these organelles slow down and pause at synapses. In contrast to previous in vitro studies, a significant increase of transport speed was observed after spontaneous activity and elevated calcium levels in vivo as well as electrically stimulated activity in acute brain slices. Together, we show a remarkable diversity in speeds and properties of three axonal organelle marker in vivo that differ from properties previously observed in vitro.
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Affiliation(s)
- Joris P Nassal
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Fiona H Murphy
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Ruud F Toonen
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Matthijs Verhage
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
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24
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Mogre SS, Christensen JR, Reck-Peterson SL, Koslover EF. Optimizing microtubule arrangements for rapid cargo capture. Biophys J 2021; 120:4918-4931. [PMID: 34687720 DOI: 10.1016/j.bpj.2021.10.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/05/2021] [Accepted: 10/18/2021] [Indexed: 10/20/2022] Open
Abstract
Cellular functions such as autophagy, cell signaling, and vesicular trafficking involve the retrograde transport of motor-driven cargo along microtubules. Typically, newly formed cargo engages in slow undirected movement from its point of origin before attaching to a microtubule. In some cell types, cargo destined for delivery to the perinuclear region relies on capture at dynein-enriched loading zones located near microtubule plus ends. Such systems include extended cell regions of neurites and fungal hyphae, where the efficiency of the initial diffusive loading process depends on the axial distribution of microtubule plus ends relative to the initial cargo position. We use analytic mean first-passage time calculations and numerical simulations to model diffusive capture processes in tubular cells, exploring how the spatial arrangement of microtubule plus ends affects the efficiency of retrograde cargo transport. Our model delineates the key features of optimal microtubule arrangements that minimize mean cargo capture times. Namely, we show that configurations with a single microtubule plus end abutting the distal tip and broadly distributed other plus ends allow for efficient capture in a variety of different scenarios for retrograde transport. Live-cell imaging of microtubule plus ends in Aspergillus nidulans hyphae indicates that their distributions exhibit these optimal qualitative features. Our results highlight important coupling effects between the distribution of microtubule tips and retrograde cargo transport, providing guiding principles for the spatial arrangement of microtubules within tubular cell regions.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California San Diego, La Jolla, California
| | - Jenna R Christensen
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California
| | - Samara L Reck-Peterson
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California; Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla, California; Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Elena F Koslover
- Department of Physics, University of California San Diego, La Jolla, California.
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25
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Safren N, Tank EM, Malik AM, Chua JP, Santoro N, Barmada SJ. Development of a specific live-cell assay for native autophagic flux. J Biol Chem 2021; 297:101003. [PMID: 34303705 PMCID: PMC8368035 DOI: 10.1016/j.jbc.2021.101003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 05/27/2021] [Accepted: 07/21/2021] [Indexed: 01/09/2023] Open
Abstract
Autophagy is an evolutionarily conserved pathway mediating the breakdown of cellular proteins and organelles. Emphasizing its pivotal nature, autophagy dysfunction contributes to many diseases; nevertheless, development of effective autophagy modulating drugs is hampered by fundamental deficiencies in available methods for measuring autophagic activity or flux. To overcome these limitations, we introduced the photoconvertible protein Dendra2 into the MAP1LC3B locus of human cells via CRISPR/Cas9 genome editing, enabling accurate and sensitive assessments of autophagy in living cells by optical pulse labeling. We used this assay to perform high-throughput drug screens of four chemical libraries comprising over 30,000 diverse compounds, identifying several clinically relevant drugs and novel autophagy modulators. A select series of candidate compounds also modulated autophagy flux in human motor neurons modified by CRISPR/Cas9 to express GFP-labeled LC3. Using automated microscopy, we tested the therapeutic potential of autophagy induction in several distinct neuronal models of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In doing so, we found that autophagy induction exhibited discordant effects, improving survival in disease models involving the RNA binding protein TDP-43, while exacerbating toxicity in neurons expressing mutant forms of UBQLN2 and C9ORF72 associated with familial ALS/FTD. These studies confirm the utility of the Dendra2-LC3 assay, while illustrating the contradictory effects of autophagy induction in different ALS/FTD subtypes.
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Affiliation(s)
- Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor Michigan, USA
| | - Elizabeth M Tank
- Department of Neurology, University of Michigan, Ann Arbor Michigan, USA
| | - Ahmed M Malik
- Department of Neurology, University of Michigan, Ann Arbor Michigan, USA
| | - Jason P Chua
- Department of Neurology, University of Michigan, Ann Arbor Michigan, USA
| | - Nicholas Santoro
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor Michigan, USA
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor Michigan, USA.
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26
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De Pace R, Britt DJ, Mercurio J, Foster AM, Djavaherian L, Hoffmann V, Abebe D, Bonifacino JS. Synaptic Vesicle Precursors and Lysosomes Are Transported by Different Mechanisms in the Axon of Mammalian Neurons. Cell Rep 2021; 31:107775. [PMID: 32553155 PMCID: PMC7478246 DOI: 10.1016/j.celrep.2020.107775] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/07/2020] [Accepted: 05/26/2020] [Indexed: 01/08/2023] Open
Abstract
BORC is a multisubunit complex previously shown to promote coupling of mammalian lysosomes and C. elegans synaptic vesicle (SV) precursors (SVPs) to kinesins for anterograde transport of these organelles along microtubule tracks. We attempted to meld these observations into a unified model for axonal transport in mammalian neurons by testing two alternative hypotheses: (1) that SV and lysosomal proteins are co-transported within a single type of “lysosome-related vesicle” and (2) that SVPs and lysosomes are distinct organelles, but both depend on BORC for axonal transport. Analyses of various types of neurons from wild-type rats and mice, as well as from BORC-deficient mice, show that neither hypothesis is correct. We find that SVPs and lysosomes are transported separately, but only lysosomes depend on BORC for axonal transport in these neurons. These findings demonstrate that SVPs and lysosomes are distinct organelles that rely on different machineries for axonal transport in mammalian neurons. De Pace et al. show that lysosomes and synaptic vesicle precursors (SVPs) are distinct organelles that move separately from the soma to the axon in rat and mouse neurons. Moreover, they demonstrate that the BLOC-1-related complex (BORC) is required for the transport of lysosomes but not SVPs in mouse neurons.
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Affiliation(s)
- Raffaella De Pace
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dylan J Britt
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jeffrey Mercurio
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Arianne M Foster
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lucas Djavaherian
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Victoria Hoffmann
- Division of Veterinary Resources, National Institutes of Health, Bethesda, MD 20892, USA
| | - Daniel Abebe
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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27
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Boecker CA, Goldsmith J, Dou D, Cajka GG, Holzbaur ELF. Increased LRRK2 kinase activity alters neuronal autophagy by disrupting the axonal transport of autophagosomes. Curr Biol 2021; 31:2140-2154.e6. [PMID: 33765413 PMCID: PMC8154747 DOI: 10.1016/j.cub.2021.02.061] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 12/14/2020] [Accepted: 02/26/2021] [Indexed: 10/21/2022]
Abstract
Parkinson's disease-causing mutations in the leucine-rich repeat kinase 2 (LRRK2) gene hyperactivate LRRK2 kinase activity and cause increased phosphorylation of Rab GTPases, important regulators of intracellular trafficking. We found that the most common LRRK2 mutation, LRRK2-G2019S, dramatically reduces the processivity of autophagosome transport in neurons in a kinase-dependent manner. This effect was consistent across an overexpression model, neurons from a G2019S knockin mouse, and human induced pluripotent stem cell (iPSC)-derived neurons gene edited to express the G2019S mutation, and the effect was reversed by genetic or pharmacological inhibition of LRRK2. Furthermore, LRRK2 hyperactivation induced by overexpression of Rab29, a known activator of LRRK2 kinase, disrupted autophagosome transport to a similar extent. Mechanistically, we found that hyperactive LRRK2 recruits the motor adaptor JNK-interacting protein 4 (JIP4) to the autophagosomal membrane, inducing abnormal activation of kinesin that we propose leads to an unproductive tug of war between anterograde and retrograde motors. Disruption of autophagosome transport correlated with a significant defect in autophagosome acidification, suggesting that the observed transport deficit impairs effective degradation of autophagosomal cargo in neurons. Our results robustly link increased LRRK2 kinase activity to defects in autophagosome transport and maturation, further implicating defective autophagy in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- C Alexander Boecker
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Juliet Goldsmith
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dan Dou
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gregory G Cajka
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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28
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Gowrishankar S, Lyons L, Rafiq NM, Roczniak-Ferguson A, De Camilli P, Ferguson SM. Overlapping roles of JIP3 and JIP4 in promoting axonal transport of lysosomes in human iPSC-derived neurons. Mol Biol Cell 2021; 32:1094-1103. [PMID: 33788575 PMCID: PMC8351540 DOI: 10.1091/mbc.e20-06-0382] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The dependence of neurons on microtubule-based motors for the movement of lysosomes over long distances raises questions about adaptations that allow neurons to meet these demands. Recently, JIP3/MAPK8IP3, a neuronally enriched putative adaptor between lysosomes and motors, was identified as a critical regulator of axonal lysosome abundance. In this study, we establish a human induced pluripotent stem cell (iPSC)-derived neuron model for the investigation of axonal lysosome transport and maturation and show that loss of JIP3 results in the accumulation of axonal lysosomes and the Alzheimer’s disease–related amyloid precursor protein (APP)-derived Aβ42 peptide. We furthermore reveal an overlapping role of the homologous JIP4 gene in lysosome axonal transport. These results establish a cellular model for investigating the relationship between lysosome axonal transport and amyloidogenic APP processing and more broadly demonstrate the utility of human iPSC–derived neurons for the investigation of neuronal cell biology and pathology.
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Affiliation(s)
- Swetha Gowrishankar
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Lila Lyons
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Nisha Mohd Rafiq
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and
| | - Agnes Roczniak-Ferguson
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair
| | - Pietro De Camilli
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair.,Howard Hughes Medical Institute, and.,Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Shawn M Ferguson
- Departments of Cell Biology and.,Neuroscience.,Program in Cellular Neuroscience, Neurodegeneration and Repair
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29
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Wang J, Fourriere L, Gleeson PA. Local Secretory Trafficking Pathways in Neurons and the Role of Dendritic Golgi Outposts in Different Cell Models. Front Mol Neurosci 2020; 13:597391. [PMID: 33324160 PMCID: PMC7726432 DOI: 10.3389/fnmol.2020.597391] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/19/2020] [Indexed: 12/18/2022] Open
Abstract
A fundamental characteristic of neurons is the relationship between the architecture of the polarized neuron and synaptic transmission between neurons. Intracellular membrane trafficking is paramount to establish and maintain neuronal structure; perturbation in trafficking results in defects in neurodevelopment and neurological disorders. Given the physical distance from the cell body to the distal sites of the axon and dendrites, transport of newly synthesized membrane proteins from the central cell body to their functional destination at remote, distal sites represents a conundrum. With the identification of secretory organelles in dendrites, including endoplasmic reticulum (ER) and Golgi outposts (GOs), recent studies have proposed local protein synthesis and trafficking distinct from the conventional anterograde transport pathways of the cell body. A variety of different model organisms, including Drosophila, zebrafish, and rodents, have been used to probe the organization and function of the local neuronal secretory network. Here, we review the evidence for local secretory trafficking pathways in dendrites in a variety of cell-based neuronal systems and discuss both the similarities and differences in the organization and role of the local secretory organelles, especially the GOs. In addition, we identify the gaps in the current knowledge and the potential advances using human induced pluripotent stem cells (iPSCs) in defining local membrane protein trafficking in human neurons and in understanding the molecular basis of neurological diseases.
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Affiliation(s)
- Jingqi Wang
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Lou Fourriere
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Paul A Gleeson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
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30
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Roy S. Finding order in slow axonal transport. Curr Opin Neurobiol 2020; 63:87-94. [PMID: 32361600 DOI: 10.1016/j.conb.2020.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 11/18/2022]
Abstract
Slow axonal transport conveys cytosolic and cytoskeletal proteins into axons and synapses at overall velocities that are several orders of magnitude slower than the fast transport of membranous organelles such as vesicles and mitochondria. The phenomenon of slow transport was characterized by in vivo pulse-chase radiolabeling studies done decades ago, and proposed models emphasized an orderly cargo-movement, with apparent cohesive transport of multiple proteins and subcellular structures along axons over weeks to months. However, visualization of cytosolic and cytoskeletal cargoes in cultured neurons at much higher temporal and spatial resolution has revealed an unexpected diversity in movement - ranging from a diffusion-like biased motion, to intermittent cargo dynamics and unusual polymerization-based transport paradigms. This review provides an updated view of slow axonal transport and explores emergent mechanistic themes in this enigmatic rate-class.
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Affiliation(s)
- Subhojit Roy
- Department of Pathology, University of California, San Diego, La Jolla, CA, United States; Department of Neurosciences, University of California, San Diego, La Jolla, CA, United States.
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31
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Palikaras K, Tavernarakis N. Regulation and roles of mitophagy at synapses. Mech Ageing Dev 2020; 187:111216. [PMID: 32084458 DOI: 10.1016/j.mad.2020.111216] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/28/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023]
Abstract
Maintenance of synaptic homeostasis is a challenging task, due to the intricate spatial organization and intense activity of synapses. Typically, synapses are located far away from the neuronal cell body, where they orchestrate neuronal signalling and communication, through neurotransmitter release. Stationary mitochondria provide energy required for synaptic vesicle cycling, and preserve ionic balance by buffering intercellular calcium at synapses. Thus, synaptic homeostasis is critically dependent on proper mitochondrial function. Indeed, defective mitochondrial metabolism is a common feature of several neurodegenerative and psychiatric disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), bipolar disorders and schizophrenia among others, which are also accompanied by excessive synaptic abnormalities. Specialized and compartmentalized quality control mechanisms have evolved to restore and maintain synaptic energy metabolism. Here, we survey recent advances towards the elucidation of the pivotal role of mitochondria in neurotransmission and implicating mitophagy in the maintenance of synaptic homeostasis during ageing.
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Affiliation(s)
- Konstantinos Palikaras
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Greece; Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion, 70013, Crete, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Greece; Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion, 70013, Crete, Greece.
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32
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Surana S, Villarroel‐Campos D, Lazo OM, Moretto E, Tosolini AP, Rhymes ER, Richter S, Sleigh JN, Schiavo G. The evolution of the axonal transport toolkit. Traffic 2019; 21:13-33. [DOI: 10.1111/tra.12710] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Sunaina Surana
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
| | - David Villarroel‐Campos
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
| | - Oscar M. Lazo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
- UK Dementia Research InstituteUniversity College London London UK
| | - Edoardo Moretto
- UK Dementia Research InstituteUniversity College London London UK
| | - Andrew P. Tosolini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
| | - Elena R. Rhymes
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
| | - Sandy Richter
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
| | - James N. Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
- UK Dementia Research InstituteUniversity College London London UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUniversity College London London UK
- UK Dementia Research InstituteUniversity College London London UK
- Discoveries Centre for Regenerative and Precision MedicineUniversity College London London UK
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