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Helmold BR, Ahrens A, Fitzgerald Z, Ozdinler PH. Spastin and alsin protein interactome analyses begin to reveal key canonical pathways and suggest novel druggable targets. Neural Regen Res 2025; 20:725-739. [PMID: 38886938 PMCID: PMC11433914 DOI: 10.4103/nrr.nrr-d-23-02068] [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: 12/21/2023] [Revised: 03/18/2024] [Accepted: 04/05/2024] [Indexed: 06/20/2024] Open
Abstract
Developing effective and long-term treatment strategies for rare and complex neurodegenerative diseases is challenging. One of the major roadblocks is the extensive heterogeneity among patients. This hinders understanding the underlying disease-causing mechanisms and building solutions that have implications for a broad spectrum of patients. One potential solution is to develop personalized medicine approaches based on strategies that target the most prevalent cellular events that are perturbed in patients. Especially in patients with a known genetic mutation, it may be possible to understand how these mutations contribute to problems that lead to neurodegeneration. Protein-protein interaction analyses offer great advantages for revealing how proteins interact, which cellular events are primarily involved in these interactions, and how they become affected when key genes are mutated in patients. This line of investigation also suggests novel druggable targets for patients with different mutations. Here, we focus on alsin and spastin, two proteins that are identified as "causative" for amyotrophic lateral sclerosis and hereditary spastic paraplegia, respectively, when mutated. Our review analyzes the protein interactome for alsin and spastin, the canonical pathways that are primarily important for each protein domain, as well as compounds that are either Food and Drug Administration-approved or are in active clinical trials concerning the affected cellular pathways. This line of research begins to pave the way for personalized medicine approaches that are desperately needed for rare neurodegenerative diseases that are complex and heterogeneous.
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Affiliation(s)
- Benjamin R. Helmold
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Angela Ahrens
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Zachary Fitzgerald
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - P. Hande Ozdinler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
- Mesulam Center for Cognitive Neurology and Alzheimer’s Disease, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Feinberg School of Medicine, Les Turner ALS Center at Northwestern University, Chicago, IL, USA
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2
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Sardina F, Carsetti C, Giorgini L, Fattorini G, Cestra G, Rinaldo C. Cul-4 inhibition rescues spastin levels and reduces defects in hereditary spastic paraplegia models. Brain 2024; 147:3534-3546. [PMID: 38551087 DOI: 10.1093/brain/awae095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 02/26/2024] [Accepted: 03/08/2024] [Indexed: 10/05/2024] Open
Abstract
Hereditary spastic paraplegias (HSPs) are degenerative motor neuron diseases characterized by progressive spasticity and weakness in the lower limbs. The most common form of HSP is due to SPG4 gene haploinsufficiency. SPG4 encodes the microtubule severing enzyme spastin. Although, there is no cure for SPG4-HSP, strategies to induce a spastin recovery are emerging as promising therapeutic approaches. Spastin protein levels are regulated by poly-ubiquitination and proteasomal-mediated degradation, in a neddylation-dependent manner. However, the molecular players involved in this regulation are unknown. Here, we show that the Cullin-4-RING E3 ubiquitin ligase complex (CRL4) regulates spastin stability. Inhibition of CRL4 increases spastin levels by preventing its poly-ubiquitination and subsequent degradation in spastin-proficient and in patient derived SPG4 haploinsufficient cells. To evaluate the role of CRL4 complex in spastin regulation in vivo, we developed a Drosophila melanogaster model of SPG4 haploinsufficiency which show alterations of synapse morphology and locomotor activity, recapitulating phenotypical defects observed in patients. Downregulation of the CRL4 complex, highly conserved in Drosophila, rescues spastin levels and the phenotypical defects observed in flies. As a proof of concept of possible pharmacological treatments, we demonstrate a recovery of spastin levels and amelioration of the SPG4-HSP-associated defects both in the fly model and in patient-derived cells by chemical inactivation of the CRL4 complex with NSC1892. Taken together, these findings show that CRL4 contributes to spastin stability regulation and that it is possible to induce spastin recovery and rescue of SPG4-HSP defects by blocking the CRL4-mediated spastin degradation.
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Affiliation(s)
- Francesca Sardina
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
| | - Claudia Carsetti
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
- Department of Biology and Biotechnology, University of Rome Sapienza, 00185, Rome, Italy
| | - Ludovica Giorgini
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
| | - Gaia Fattorini
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
- Department of Biology and Biotechnology, University of Rome Sapienza, 00185, Rome, Italy
| | - Gianluca Cestra
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
- Department of Biology and Biotechnology, University of Rome Sapienza, 00185, Rome, Italy
- Fondazione Santa Lucia IRCCS, c/o CERC, 00179, Rome, Italy
| | - Cinzia Rinaldo
- National Research Council (CNR), Institute of Molecular Biology and Pathology (IBPM), c/o University of Rome Sapienza, 00185 Rome, Italy
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Lobato AG, Ortiz-Vega N, Canic T, Tao X, Bucan N, Ruan K, Rebelo AP, Schule R, Zuchner S, Syed S, Zhai RG. Loss of Fic causes progressive neurodegeneration in a Drosophila model of hereditary spastic paraplegia. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167348. [PMID: 38986817 DOI: 10.1016/j.bbadis.2024.167348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 07/03/2024] [Accepted: 07/03/2024] [Indexed: 07/12/2024]
Abstract
Hereditary Spastic Paraplegia (HSP) is a group of rare inherited disorders characterized by progressive weakness and spasticity of the legs. Recent newly discovered biallelic variants in the gene FICD were found in patients with a highly similar phenotype to early onset HSP. FICD encodes filamentation induced by cAMP domain protein. FICD is involved in the AMPylation and deAMPylation protein modifications of the endoplasmic reticulum (ER) chaperone BIP, a major constituent of the ER that regulates the unfolded protein response. Although several biochemical properties of FICD have been characterized, the neurological function of FICD and the pathological mechanism underlying HSP are unknown. We established a Drosophila model to gain mechanistic understanding of the function of FICD in HSP pathogenesis, and specifically the role of BIP in neuromuscular physiology. Our studies on Drosophila Fic null mutants uncovered that loss of Fic resulted in locomotor impairment and reduced levels of BIP in the motor neuron circuitry, as well as increased reactive oxygen species (ROS) in the ventral nerve cord of Fic null mutants. Finally, feeding Drosophila Fic null mutants with chemical chaperones PBA or TUDCA, or treatment of patient fibroblasts with PBA, reduced the ROS accumulation. The neuronal phenotypes of Fic null mutants recapitulate several clinical features of HSP patients and further reveal cellular patho-mechanisms. By modeling FICD in Drosophila, we provide potential targets for intervention for HSP, and advance fundamental biology that is important for understanding related rare and common neuromuscular diseases.
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Affiliation(s)
- Amanda G Lobato
- Department of Neurology, University of Chicago, Chicago, IL, USA; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA; Graduate Program in Human Genetics and Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Natalie Ortiz-Vega
- Department of Neurology, University of Chicago, Chicago, IL, USA; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA; Graduate Program in Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Tijana Canic
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA; Graduate Program in Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Xianzun Tao
- Department of Neurology, University of Chicago, Chicago, IL, USA; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Nika Bucan
- Undergraduate Program in Neuroscience, University of Miami, Coral Gables, FL, USA
| | - Kai Ruan
- Department of Neurology, University of Chicago, Chicago, IL, USA; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Adriana P Rebelo
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Rebecca Schule
- Hertie Institute for Clinical Brain Research (HIH), Center of Neurology, University of Tübingen, Tübingen, Germany; German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sheyum Syed
- Department of Physics, University of Miami, Coral Gables, FL, USA
| | - R Grace Zhai
- Department of Neurology, University of Chicago, Chicago, IL, USA; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA.
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4
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Gillard G, Röper K. β-H-Spectrin is a key component of an apical-medial hub of proteins during cell wedging in tube morphogenesis. J Cell Sci 2024; 137:jcs261946. [PMID: 38988298 PMCID: PMC11361641 DOI: 10.1242/jcs.261946] [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: 01/08/2024] [Accepted: 07/01/2024] [Indexed: 07/12/2024] Open
Abstract
Coordinated cell shape changes are a major driver of tissue morphogenesis, with apical constriction of epithelial cells leading to tissue bending. We previously identified that interplay between the apical-medial actomyosin, which drives apical constriction, and the underlying longitudinal microtubule array has a key role during tube budding of salivary glands in the Drosophila embryo. At this microtubule-actomyosin interface, a hub of proteins accumulates, and we have shown before that this hub includes the microtubule-actin crosslinker Shot and the microtubule minus-end-binding protein Patronin. Here, we identify two actin-crosslinkers, β-heavy (H)-Spectrin (also known as Karst) and Filamin (also known as Cheerio), and the multi-PDZ-domain protein Big bang as components of the protein hub. We show that tissue-specific degradation of β-H-Spectrin leads to reduction of apical-medial F-actin, Shot, Patronin and Big bang, as well as concomitant defects in apical constriction, but that residual Patronin is still sufficient to assist microtubule reorganisation. We find that, unlike Patronin and Shot, neither β-H-Spectrin nor Big bang require microtubules for their localisation. β-H-Spectrin is instead recruited via binding to apical-medial phosphoinositides, and overexpression of the C-terminal pleckstrin homology domain-containing region of β-H-Spectrin (β-H-33) displaces endogenous β-H-Spectrin and leads to strong morphogenetic defects. This protein hub therefore requires the synergy and coincidence of membrane- and microtubule-associated components for its assembly and function in sustaining apical constriction during tubulogenesis.
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Affiliation(s)
- Ghislain Gillard
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Katja Röper
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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5
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Ray T, Shi D, Harris TJC. Confinement promotes nematic alignment of spindle-shaped cells during Drosophila embryogenesis. Development 2024; 151:dev202577. [PMID: 38864272 PMCID: PMC11234378 DOI: 10.1242/dev.202577] [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: 11/30/2023] [Accepted: 06/05/2024] [Indexed: 06/13/2024]
Abstract
Tissue morphogenesis is often controlled by actomyosin networks pulling on adherens junctions (AJs), but junctional myosin levels vary. At an extreme, the Drosophila embryo amnioserosa forms a horseshoe-shaped strip of aligned, spindle-shaped cells lacking junctional myosin. What are the bases of amnioserosal cell interactions and alignment? Compared with surrounding tissue, we find that amnioserosal AJ continuity has lesser dependence on α-catenin, the mediator of AJ-actomyosin association, and greater dependence on Bazooka/Par-3, a junction-associated scaffold protein. Microtubule bundles also run along amnioserosal AJs and support their long-range curvilinearity. Amnioserosal confinement is apparent from partial overlap of its spindle-shaped cells, its outward bulging from surrounding tissue and from compressive stress detected within the amnioserosa. Genetic manipulations that alter amnioserosal confinement by surrounding tissue also result in amnioserosal cells losing alignment and gaining topological defects characteristic of nematically ordered systems. With Bazooka depletion, confinement by surrounding tissue appears to be relatively normal and amnioserosal cells align despite their AJ fragmentation. Overall, the fully elongated amnioserosa appears to form through tissue-autonomous generation of spindle-shaped cells that nematically align in response to confinement by surrounding tissue.
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Affiliation(s)
- Tirthankar Ray
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Damo Shi
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Tony J. C. Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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6
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Kang H, Yang Y, Wei B. Synthetic molecular switches driven by DNA-modifying enzymes. Nat Commun 2024; 15:3781. [PMID: 38710688 DOI: 10.1038/s41467-024-47742-2] [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: 08/08/2023] [Accepted: 04/10/2024] [Indexed: 05/08/2024] Open
Abstract
Taking inspiration from natural systems, in which molecular switches are ubiquitous in the biochemistry regulatory network, we aim to design and construct synthetic molecular switches driven by DNA-modifying enzymes, such as DNA polymerase and nicking endonuclease. The enzymatic treatments on our synthetic DNA constructs controllably switch ON or OFF the sticky end cohesion and in turn cascade to the structural association or disassociation. Here we showcase the concept in multiple DNA nanostructure systems with robust assembly/disassembly performance. The switch mechanisms are first illustrated in minimalist systems with a few DNA strands. Then the ON/OFF switches are realized in complex DNA lattice and origami systems with designated morphological changes responsive to the specific enzymatic treatments.
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Affiliation(s)
- Hong Kang
- School of Life Sciences, Center for Synthetic and Systems Biology, Tsinghua University, 100084, Beijing, China
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Yuexuan Yang
- School of Life Sciences, Center for Synthetic and Systems Biology, Tsinghua University, 100084, Beijing, China
| | - Bryan Wei
- School of Life Sciences, Center for Synthetic and Systems Biology, Tsinghua University, 100084, Beijing, China.
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7
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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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Damiani D, Baggiani M, Della Vecchia S, Naef V, Santorelli FM. Pluripotent Stem Cells as a Preclinical Cellular Model for Studying Hereditary Spastic Paraplegias. Int J Mol Sci 2024; 25:2615. [PMID: 38473862 DOI: 10.3390/ijms25052615] [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: 01/08/2024] [Revised: 02/12/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Hereditary spastic paraplegias (HSPs) comprise a family of degenerative diseases mostly hitting descending axons of corticospinal neurons. Depending on the gene and mutation involved, the disease could present as a pure form with limb spasticity, or a complex form associated with cerebellar and/or cortical signs such as ataxia, dysarthria, epilepsy, and intellectual disability. The progressive nature of HSPs invariably leads patients to require walking canes or wheelchairs over time. Despite several attempts to ameliorate the life quality of patients that have been tested, current therapeutical approaches are just symptomatic, as no cure is available. Progress in research in the last two decades has identified a vast number of genes involved in HSP etiology, using cellular and animal models generated on purpose. Although unanimously considered invaluable tools for basic research, those systems are rarely predictive for the establishment of a therapeutic approach. The advent of induced pluripotent stem (iPS) cells allowed instead the direct study of morphological and molecular properties of the patient's affected neurons generated upon in vitro differentiation. In this review, we revisited all the present literature recently published regarding the use of iPS cells to differentiate HSP patient-specific neurons. Most studies have defined patient-derived neurons as a reliable model to faithfully mimic HSP in vitro, discovering original findings through immunological and -omics approaches, and providing a platform to screen novel or repurposed drugs. Thereby, one of the biggest hopes of current HSP research regards the use of patient-derived iPS cells to expand basic knowledge on the disease, while simultaneously establishing new therapeutic treatments for both generalized and personalized approaches in daily medical practice.
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Affiliation(s)
- Devid Damiani
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Via dei Giacinti 2, 56128 Pisa, Italy
| | - Matteo Baggiani
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Via dei Giacinti 2, 56128 Pisa, Italy
| | - Stefania Della Vecchia
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Via dei Giacinti 2, 56128 Pisa, Italy
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Valentina Naef
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Via dei Giacinti 2, 56128 Pisa, Italy
| | - Filippo Maria Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Via dei Giacinti 2, 56128 Pisa, Italy
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Deretic J, Odabasi E, Firat-Karalar EN. The multifaceted roles of microtubule-associated proteins in the primary cilium and ciliopathies. J Cell Sci 2023; 136:jcs261148. [PMID: 38095645 DOI: 10.1242/jcs.261148] [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] [Indexed: 12/18/2023] Open
Abstract
The primary cilium is a conserved microtubule-based organelle that is critical for transducing developmental, sensory and homeostatic signaling pathways. It comprises an axoneme with nine parallel doublet microtubules extending from the basal body, surrounded by the ciliary membrane. The axoneme exhibits remarkable stability, serving as the skeleton of the cilium in order to maintain its shape and provide tracks to ciliary trafficking complexes. Although ciliary trafficking and signaling have been exhaustively characterized over the years, less is known about the unique structural and functional complexities of the axoneme. Recent work has yielded new insights into the mechanisms by which the axoneme is built with its proper length and architecture, particularly regarding the activity of microtubule-associated proteins (MAPs). In this Review, we first summarize current knowledge about the architecture, composition and specialized compartments of the primary cilium. Next, we discuss the mechanistic underpinnings of how a functional cilium is assembled, maintained and disassembled through the regulation of its axonemal microtubules. We conclude by examining the diverse localizations and functions of ciliary MAPs for the pathobiology of ciliary diseases.
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Affiliation(s)
- Jovana Deretic
- Department of Molecular Biology and Genetics, Koç University, Istanbul 34450, Turkey
| | - Ezgi Odabasi
- Department of Molecular Biology and Genetics, Koç University, Istanbul 34450, Turkey
| | - Elif Nur Firat-Karalar
- Department of Molecular Biology and Genetics, Koç University, Istanbul 34450, Turkey
- School of Medicine, Koç University, Istanbul 34450, Turkey
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Abstract
Neurons are markedly compartmentalized, which makes them reliant on axonal transport to maintain their health. Axonal transport is important for anterograde delivery of newly synthesized macromolecules and organelles from the cell body to the synapse and for the retrograde delivery of signaling endosomes and autophagosomes for degradation. Dysregulation of axonal transport occurs early in neurodegenerative diseases and plays a key role in axonal degeneration. Here, we provide an overview of mechanisms for regulation of axonal transport; discuss how these mechanisms are disrupted in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, hereditary spastic paraplegia, amyotrophic lateral sclerosis, and Charcot-Marie-Tooth disease; and discuss therapeutic approaches targeting axonal transport.
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Kang HM, Kim DH, Kim M, Min Y, Jeong B, Noh KH, Lee DY, Cho HS, Kim NS, Jung CR, Lim JH. FBXL17/spastin axis as a novel therapeutic target of hereditary spastic paraplegia. Cell Biosci 2022; 12:110. [PMID: 35869491 PMCID: PMC9308218 DOI: 10.1186/s13578-022-00851-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/11/2022] [Indexed: 11/12/2022] Open
Abstract
Background Spastin significantly influences microtubule regulation in neurons and is implicated in the pathogenesis of hereditary spastic paraplegia (HSP). However, post-translational regulation of the spastin protein remains nebulous. The association between E3 ubiquitin ligase and spastin provides a potential therapeutic strategy. Results As evidenced by protein chip analysis, FBXL17 inversely correlated with SPAST-M1 at the protein level in vitro and, also in vivo during embryonic developmental stage. SPAST-M1 protein interacted with FBXL17 specifically via the BTB domain at the N-terminus of SPAST-M1. The SCFFBXL17 E3 ubiquitin ligase complex degraded SPAST-M1 protein in the nuclear fraction in a proteasome-dependent manner. SPAST phosphorylation occurred only in the cytoplasmic fraction by CK2 and was involved in poly-ubiquitination. Inhibition of SCFFBXL17 E3 ubiquitin ligase by small chemical and FBXL17 shRNA decreased proteasome-dependent degradation of SPAST-M1 and induced axonal extension. The SPAST Y52C mutant, harboring abnormality in BTB domain could not interact with FBXL17, thereby escaping protein regulation by the SCFFBXL17 E3 ubiquitin ligase complex, resulting in loss of functionality with aberrant quantity. Although this mutant showed shortening of axonal outgrowth, low rate proliferation, and poor differentiation capacity in a 3D model, this phenotype was rescued by inhibiting SCFFBXL17 E3 ubiquitin ligase. Conclusions We discovered that a novel pathway, FBXL17-SPAST was involved in pathogenicity of HSP by the loss of function and the quantitative regulation. This result suggested that targeting FBXL17 could provide new insight into HSP therapeutics. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00851-1.
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Guru A, Saravanan S, Sharma D, Narasimha M. The microtubule end-binding proteins EB1 and Patronin modulate the spatiotemporal dynamics of myosin and pattern pulsed apical constriction. Development 2022; 149:284823. [PMID: 36440630 DOI: 10.1242/dev.199759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/31/2022] [Indexed: 11/29/2022]
Abstract
Apical constriction powers amnioserosa contraction during Drosophila dorsal closure. The nucleation, movement and dispersal of apicomedial actomyosin complexes generates pulsed apical constrictions during early closure. Persistent apicomedial and circumapical actomyosin complexes drive unpulsed constrictions that follow. Here, we show that the microtubule end-binding proteins EB1 and Patronin pattern constriction dynamics and contraction kinetics by coordinating the balance of actomyosin forces in the apical plane. We find that microtubule growth from moving Patronin platforms governs the spatiotemporal dynamics of apicomedial myosin through the regulation of RhoGTPase signaling by transient EB1-RhoGEF2 interactions. We uncover the dynamic reorganization of a subset of short non-centrosomally nucleated apical microtubules that surround the coalescing apicomedial myosin complex, trail behind it as it moves and disperse as the complex dissolves. We demonstrate that apical microtubule reorganization is sensitive to Patronin levels. Microtubule depolymerization compromised apical myosin enrichment and altered constriction dynamics. Together, our findings uncover the importance of reorganization of an intact apical microtubule meshwork, by moving Patronin platforms and growing microtubule ends, in enabling the spatiotemporal modulation of actomyosin contractility and, through it, apical constriction.
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Affiliation(s)
- Anwesha Guru
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
| | - Surat Saravanan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
| | - Deepanshu Sharma
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
| | - Maithreyi Narasimha
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
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Costamagna D, Casters V, Beltrà M, Sampaolesi M, Van Campenhout A, Ortibus E, Desloovere K, Duelen R. Autologous iPSC-Derived Human Neuromuscular Junction to Model the Pathophysiology of Hereditary Spastic Paraplegia. Cells 2022; 11:3351. [PMID: 36359747 PMCID: PMC9655384 DOI: 10.3390/cells11213351] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/14/2022] [Accepted: 10/19/2022] [Indexed: 08/27/2023] Open
Abstract
Hereditary spastic paraplegia (HSP) is a heterogeneous group of genetic neurodegenerative disorders, characterized by progressive lower limb spasticity and weakness resulting from retrograde axonal degeneration of motor neurons (MNs). Here, we generated in vitro human neuromuscular junctions (NMJs) from five HSP patient-specific induced pluripotent stem cell (hiPSC) lines, by means of microfluidic strategy, to model disease-relevant neuropathologic processes. The strength of our NMJ model lies in the generation of lower MNs and myotubes from autologous hiPSC origin, maintaining the genetic background of the HSP patient donors in both cell types and in the cellular organization due to the microfluidic devices. Three patients characterized by a mutation in the SPG3a gene, encoding the ATLASTIN GTPase 1 protein, and two patients with a mutation in the SPG4 gene, encoding the SPASTIN protein, were included in this study. Differentiation of the HSP-derived lines gave rise to lower MNs that could recapitulate pathological hallmarks, such as axonal swellings with accumulation of Acetyl-α-TUBULIN and reduction of SPASTIN levels. Furthermore, NMJs from HSP-derived lines were lower in number and in contact point complexity, denoting an impaired NMJ profile, also confirmed by some alterations in genes encoding for proteins associated with microtubules and responsible for axonal transport. Considering the complexity of HSP, these patient-derived neuronal and skeletal muscle cell co-cultures offer unique tools to study the pathologic mechanisms and explore novel treatment options for rescuing axonal defects and diverse cellular processes, including membrane trafficking, intracellular motility and protein degradation in HSP.
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Affiliation(s)
- Domiziana Costamagna
- Stem Cell and Developmental Biology, Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium
- Research Group for Neurorehabilitation, Department of Rehabilitation Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Valérie Casters
- Research Group for Neurorehabilitation, Department of Rehabilitation Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Marc Beltrà
- Department of Clinical and Biological Sciences, University of Torino, 10125 Torino, Italy
| | - Maurilio Sampaolesi
- Stem Cell and Developmental Biology, Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium
| | - Anja Van Campenhout
- Locomotor and Neurological Disorder, Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium
- Department of Orthopedic Surgery, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Els Ortibus
- Locomotor and Neurological Disorder, Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium
- Department of Pediatric Neurology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Kaat Desloovere
- Research Group for Neurorehabilitation, Department of Rehabilitation Sciences, KU Leuven, 3000 Leuven, Belgium
- Clinical Motion Analysis Laboratory, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Robin Duelen
- Stem Cell and Developmental Biology, Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium
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14
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Costa AC, Sousa MM. The Role of Spastin in Axon Biology. Front Cell Dev Biol 2022; 10:934522. [PMID: 35865632 PMCID: PMC9294387 DOI: 10.3389/fcell.2022.934522] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 06/07/2022] [Indexed: 12/05/2022] Open
Abstract
Neurons are highly polarized cells with elaborate shapes that allow them to perform their function. In neurons, microtubule organization—length, density, and dynamics—are essential for the establishment of polarity, growth, and transport. A mounting body of evidence shows that modulation of the microtubule cytoskeleton by microtubule-associated proteins fine tunes key aspects of neuronal cell biology. In this respect, microtubule severing enzymes—spastin, katanin and fidgetin—a group of microtubule-associated proteins that bind to and generate internal breaks in the microtubule lattice, are emerging as key modulators of the microtubule cytoskeleton in different model systems. In this review, we provide an integrative view on the latest research demonstrating the key role of spastin in neurons, specifically in the context of axonal cell biology. We focus on the function of spastin in the regulation of microtubule organization, and axonal transport, that underlie its importance in the intricate control of axon growth, branching and regeneration.
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Affiliation(s)
- Ana Catarina Costa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- Graduate Program in Molecular and Cell Biology, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
| | - Monica Mendes Sousa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
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15
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Shree S, Sutradhar S, Trottier O, Tu Y, Liang X, Howard J. Dynamic instability of dendrite tips generates the highly branched morphologies of sensory neurons. SCIENCE ADVANCES 2022; 8:eabn0080. [PMID: 35767611 PMCID: PMC9242452 DOI: 10.1126/sciadv.abn0080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
The highly ramified arbors of neuronal dendrites provide the substrate for the high connectivity and computational power of the brain. Altered dendritic morphology is associated with neuronal diseases. Many molecules have been shown to play crucial roles in shaping and maintaining dendrite morphology. However, the underlying principles by which molecular interactions generate branched morphologies are not understood. To elucidate these principles, we visualized the growth of dendrites throughout larval development of Drosophila sensory neurons and found that the tips of dendrites undergo dynamic instability, transitioning rapidly and stochastically between growing, shrinking, and paused states. By incorporating these measured dynamics into an agent-based computational model, we showed that the complex and highly variable dendritic morphologies of these cells are a consequence of the stochastic dynamics of their dendrite tips. These principles may generalize to branching of other neuronal cell types, as well as to branching at the subcellular and tissue levels.
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Affiliation(s)
- Sonal Shree
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Sabyasachi Sutradhar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Olivier Trottier
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
- Department of Physics, Yale University, New Haven, CT 06511, USA
| | - Yuhai Tu
- IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, USA
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
- Department of Physics, Yale University, New Haven, CT 06511, USA
- Quantitative Biology Institute, Yale University, New Haven, CT 06511, USA
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16
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Zajac AL, Horne-Badovinac S. Kinesin-directed secretion of basement membrane proteins to a subdomain of the basolateral surface in Drosophila epithelial cells. Curr Biol 2022; 32:735-748.e10. [PMID: 35021047 PMCID: PMC8891071 DOI: 10.1016/j.cub.2021.12.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 11/23/2021] [Accepted: 12/09/2021] [Indexed: 12/26/2022]
Abstract
Epithelial tissues are lined with a sheet-like basement membrane (BM) extracellular matrix at their basal surfaces that plays essential roles in adhesion and signaling. BMs also provide mechanical support to guide morphogenesis. Despite their importance, we know little about how epithelial cells secrete and assemble BMs during development. BM proteins are sorted into a basolateral secretory pathway distinct from other basolateral proteins. Because BM proteins self-assemble into networks, and the BM lines only a small portion of the basolateral domain, we hypothesized that the site of BM protein secretion might be tightly controlled. Using the Drosophila follicular epithelium, we show that kinesin-3 and kinesin-1 motors work together to define this secretion site. Similar to all epithelia, the follicle cells have polarized microtubules (MTs) along their apical-basal axes. These cells collectively migrate, and they also have polarized MTs along the migratory axis at their basal surfaces. We find follicle cell MTs form one interconnected network, which allows kinesins to transport Rab10+ BM secretory vesicles both basally and to the trailing edge of each cell. This positions them near the basal surface and the basal-most region of the lateral domain for exocytosis. When kinesin transport is disrupted, the site of BM protein secretion is expanded, and ectopic BM networks form between cells that impede migration and disrupt tissue architecture. These results show how epithelial cells can define a subdomain on their basolateral surface through MT-based transport and highlight the importance of controlling the exocytic site of network-forming proteins.
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Affiliation(s)
- Allison L. Zajac
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
| | - Sally Horne-Badovinac
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
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17
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TREX1 Deficiency Induces ER Stress-Mediated Neuronal Cell Death by Disrupting Ca 2+ Homeostasis. Mol Neurobiol 2022; 59:1398-1418. [PMID: 34997539 PMCID: PMC8882114 DOI: 10.1007/s12035-021-02631-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/01/2021] [Indexed: 11/09/2022]
Abstract
TREX1 is an exonuclease that degrades extranuclear DNA species in mammalian cells. Herein, we show a novel mechanism by which TREX1 interacts with the BiP/GRP78 and TREX1 deficiency triggers ER stress through the accumulation of single-stranded DNA and activates unfolded protein response (UPR) signaling via the disruption of the TREX1-BiP/GRP78 interaction. In TREX1 knockdown cells, the activation of ER stress signaling disrupted ER Ca2+ homeostasis via the ERO1α-IP3R1-CaMKII pathway, leading to neuronal cell death. Moreover, TREX1 knockdown dysregulated the Golgi-microtubule network through Golgi fragmentation and decreased Ac-α-tubulin levels, contributing to neuronal injury. These alterations were also observed in neuronal cells harboring a TREX1 mutation (V91M) that has been identified in hereditary spastic paraplegia (HSP) patients in Korea. Notably, this mutation leads to defects in the TREX1-BiP/GRP78 interaction and mislocalization of TREX1 from the ER and possible disruption of the Golgi-microtubule network. In summary, the current study reveals TREX1 as a novel regulator of the BiP/GRP78 interaction and shows that TREX1 deficiency promotes ER stress-mediated neuronal cell death, which indicates that TREX1 may hold promise as a therapeutic target for neurodegenerative diseases such as HSP.
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18
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Chen R, Du S, Yao Y, Zhang L, Luo J, Shen Y, Xu Z, Zeng X, Zhang L, Liu M, Yin C, Tang B, Tan J, Xu X, Liu JY. A Novel SPAST Mutation Results in Spastin Accumulation and Defects in Microtubule Dynamics. Mov Disord 2021; 37:598-607. [PMID: 34927746 PMCID: PMC9300132 DOI: 10.1002/mds.28885] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 11/24/2021] [Accepted: 11/27/2021] [Indexed: 11/25/2022] Open
Abstract
Background Haploinsufficiency is widely accepted as the pathogenic mechanism of spastic paraplegia type 4 (SPG4). However, there are some cases that cannot be explained by reduced function of the spastin protein encoded by SPAST. Objectives To identify the causative gene of autosomal dominant hereditary spastic paraplegia in three large Chinese families and explore the pathological mechanism of a spastin variant. Methods Three large Chinese hereditary spastic paraplegia families with a total of 247 individuals (67 patients) were investigated, of whom 59 members were recruited to the study. Genetic testing was performed to identify the causative gene. Western blotting and immunofluorescence were used to analyze the effects of the mutant proteins in vitro. Results In the three hereditary spastic paraplegia families, of whom three index cases were misdiagnosed as other types of neurological diseases, a novel c.985dupA (p.Met329Asnfs*3) variant in SPAST was identified and was shown to cosegregate with the phenotype in the three families. The c.985dupA mutation produced two truncated mutants (mutant M1 and M87 isoforms) that accumulated to a higher level than their wild‐type counterparts. Furthermore, the mutant M1 isoform heavily decorated the microtubules and rendered them resistant to depolymerization. In contrast, the mutant M87 isoform was diffusely localized in both the nucleus and the cytoplasm, could not decorate microtubules, and was not able to promote microtubule disassembly. Conclusions SPAST mutations leading to premature stop codons do not always act through haploinsufficiency. The truncated spastin may damage the corticospinal tracts through an isoform‐specific toxic effect.
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Affiliation(s)
- Rui Chen
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Shiyue Du
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Yanyi Yao
- Medical Genetics Center, Maternal and Child Health Hospital of Hubei Province, Wuhan, China
| | - Lu Zhang
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Junyu Luo
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Yinhua Shen
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Zhenping Xu
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, China
| | - Xiaomei Zeng
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Luoying Zhang
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Mugen Liu
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Chuang Yin
- Department of Neurology, Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
| | - Jun Tan
- Department of Neurology, Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Xuan Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Jing Yu Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
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19
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Liu Q, Zhang G, Ji Z, Lin H. Molecular and cellular mechanisms of spastin in neural development and disease (Review). Int J Mol Med 2021; 48:218. [PMID: 34664680 PMCID: PMC8547542 DOI: 10.3892/ijmm.2021.5051] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/29/2021] [Indexed: 12/26/2022] Open
Abstract
Spastin is a microtubule (MT)‑severing enzyme identified from mutations of hereditary spastic paraplegia in 1999 and extensive studies indicate its vital role in various cellular activities. In the past two decades, efforts have been made to understand the underlying molecular mechanisms of how spastin is linked to neural development and disease. Recent studies on spastin have unraveled the mechanistic processes of its MT‑severing activity and revealed that spastin acts as an MT amplifier to mediate its remodeling, thus providing valuable insight into the molecular roles of spastin under physiological conditions. In addition, recent research has revealed multiple novel molecular mechanisms of spastin in cellular biological pathways, including endoplasmic reticulum shaping, calcium trafficking, fatty acid trafficking, as well as endosomal fission and trafficking. These processes are closely involved in axonal and dendritic development and maintenance. The current review presents recent biological advances regarding the molecular mechanisms of spastin at the cellular level and provides insight into how it affects neural development and disease.
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Affiliation(s)
- Qiuling Liu
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Guowei Zhang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Zhisheng Ji
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
| | - Hongsheng Lin
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, P.R. China
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20
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Bu S, Yong WL, Lim BJW, Kondo S, Yu F. A systematic analysis of microtubule-destabilizing factors during dendrite pruning in Drosophila. EMBO Rep 2021; 22:e52679. [PMID: 34338441 DOI: 10.15252/embr.202152679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 11/09/2022] Open
Abstract
It has long been thought that microtubule disassembly, one of the earliest cellular events, contributes to neuronal pruning and neurodegeneration in development and disease. However, how microtubule disassembly drives neuronal pruning remains poorly understood. Here, we conduct a systematic investigation of various microtubule-destabilizing factors and identify exchange factor for Arf6 (Efa6) and Stathmin (Stai) as new regulators of dendrite pruning in ddaC sensory neurons during Drosophila metamorphosis. We show that Efa6 is both necessary and sufficient to regulate dendrite pruning. Interestingly, Efa6 and Stai facilitate microtubule turnover and disassembly prior to dendrite pruning without compromising the minus-end-out microtubule orientation in dendrites. Moreover, our pharmacological and genetic manipulations strongly support a key role of microtubule disassembly in promoting dendrite pruning. Thus, this systematic study highlights the importance of two selective microtubule destabilizers in dendrite pruning and substantiates a causal link between microtubule disassembly and neuronal pruning.
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Affiliation(s)
- Shufeng Bu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Wei Lin Yong
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Bryan Jian Wei Lim
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shu Kondo
- Invertebrate Genetics Laboratory, National Institute of Genetics, Shizuoka, Japan
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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21
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Zhang G, Li S, Cheng KW, Chou TF. AAA ATPases as therapeutic targets: Structure, functions, and small-molecule inhibitors. Eur J Med Chem 2021; 219:113446. [PMID: 33873056 PMCID: PMC8165034 DOI: 10.1016/j.ejmech.2021.113446] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 03/21/2021] [Accepted: 03/30/2021] [Indexed: 01/07/2023]
Abstract
ATPases Associated with Diverse Cellular Activity (AAA ATPase) are essential enzymes found in all organisms. They are involved in various processes such as DNA replication, protein degradation, membrane fusion, microtubule serving, peroxisome biogenesis, signal transduction, and the regulation of gene expression. Due to the importance of AAA ATPases, several researchers identified and developed small-molecule inhibitors against these enzymes. We discuss six AAA ATPases that are potential drug targets and have well-developed inhibitors. We compare available structures that suggest significant differences of the ATP binding pockets among the AAA ATPases with or without ligand. The distances from ADP to the His20 in the His-Ser-His motif and the Arg finger (Arg353 or Arg378) in both RUVBL1/2 complex structures bound with or without ADP have significant differences, suggesting dramatically different interactions of the binding site with ADP. Taken together, the inhibitors of six well-studied AAA ATPases and their structural information suggest further development of specific AAA ATPase inhibitors due to difference in their structures. Future chemical biology coupled with proteomic approaches could be employed to develop variant specific, complex specific, and pathway specific inhibitors or activators for AAA ATPase proteins.
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Affiliation(s)
- Gang Zhang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, United States.
| | - Shan Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, United States
| | - Kai-Wen Cheng
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, United States
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, United States.
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22
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A release-and-capture mechanism generates an essential non-centrosomal microtubule array during tube budding. Nat Commun 2021; 12:4096. [PMID: 34215746 PMCID: PMC8253823 DOI: 10.1038/s41467-021-24332-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 05/27/2021] [Indexed: 11/08/2022] Open
Abstract
Non-centrosomal microtubule arrays serve crucial functions in cells, yet the mechanisms of their generation are poorly understood. During budding of the epithelial tubes of the salivary glands in the Drosophila embryo, we previously demonstrated that the activity of pulsatile apical-medial actomyosin depends on a longitudinal non-centrosomal microtubule array. Here we uncover that the exit from the last embryonic division cycle of the epidermal cells of the salivary gland placode leads to one centrosome in the cells losing all microtubule-nucleation capacity. This restriction of nucleation activity to the second, Centrobin-enriched, centrosome is key for proper morphogenesis. Furthermore, the microtubule-severing protein Katanin and the minus-end-binding protein Patronin accumulate in an apical-medial position only in placodal cells. Loss of either in the placode prevents formation of the longitudinal microtubule array and leads to loss of apical-medial actomyosin and impaired apical constriction. We thus propose a mechanism whereby Katanin-severing at the single active centrosome releases microtubule minus-ends that are then anchored by apical-medial Patronin to promote formation of the longitudinal microtubule array crucial for apical constriction and tube formation.
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23
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Sun L, Cui L, Liu Z, Wang Q, Xue Z, Wu M, Sun T, Mao D, Ni J, Pastor-Pareja JC, Liang X. Katanin p60-like 1 sculpts the cytoskeleton in mechanosensory cilia. J Cell Biol 2021; 220:211570. [PMID: 33263729 PMCID: PMC7717695 DOI: 10.1083/jcb.202004184] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/28/2020] [Accepted: 10/20/2020] [Indexed: 12/20/2022] Open
Abstract
Mechanoreceptor cells develop a specialized cytoskeleton that plays structural and sensory roles at the site of mechanotransduction. However, little is known about how the cytoskeleton is organized and formed. Using electron tomography and live-cell imaging, we resolve the 3D structure and dynamics of the microtubule-based cytoskeleton in fly campaniform mechanosensory cilia. Investigating the formation of the cytoskeleton, we find that katanin p60-like 1 (kat-60L1), a neuronal type of microtubule-severing enzyme, serves two functions. First, it amplifies the mass of microtubules to form the dense microtubule arrays inside the sensory cilia. Second, it generates short microtubules that are required to build the nanoscopic cytoskeleton at the mechanotransduction site. Additional analyses further reveal the functional roles of Patronin and other potential factors in the local regulatory network. In all, our results characterize the specialized cytoskeleton in fly external mechanosensory cilia at near-molecular resolution and provide mechanistic insights into how it is formed.
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Affiliation(s)
- Landi Sun
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lihong Cui
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhen Liu
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Qixuan Wang
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhaoyu Xue
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Menghua Wu
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Tianhui Sun
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Decai Mao
- School of Medicine, Tsinghua University, Beijing, China
| | - Jianquan Ni
- School of Medicine, Tsinghua University, Beijing, China
| | - José Carlos Pastor-Pareja
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
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24
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Le TP, Chung S. Regulation of apical constriction via microtubule- and Rab11-dependent apical transport during tissue invagination. Mol Biol Cell 2021; 32:1033-1047. [PMID: 33788621 PMCID: PMC8101490 DOI: 10.1091/mbc.e21-01-0021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The formation of an epithelial tube is a fundamental process for organogenesis. During Drosophila embryonic salivary gland (SG) invagination, Folded gastrulation (Fog)-dependent Rho-associated kinase (Rok) promotes contractile apical myosin formation to drive apical constriction. Microtubules (MTs) are also crucial for this process and are required for forming and maintaining apicomedial myosin. However, the underlying mechanism that coordinates actomyosin and MT networks still remains elusive. Here, we show that MT-dependent intracellular trafficking regulates apical constriction during SG invagination. Key components involved in protein trafficking, such as Rab11 and Nuclear fallout (Nuf), are apically enriched near the SG invagination pit in a MT-dependent manner. Disruption of the MT networks or knockdown of Rab11 impairs apicomedial myosin formation and apical constriction. We show that MTs and Rab11 are required for apical enrichment of the Fog ligand and the continuous distribution of the apical determinant protein Crumbs (Crb) and the key adherens junction protein E-Cadherin (E-Cad) along junctions. Targeted knockdown of crb or E-Cad in the SG disrupts apical myosin networks and results in apical constriction defects. Our data suggest a role of MT- and Rab11-dependent intracellular trafficking in regulating actomyosin networks and cell junctions to coordinate cell behaviors during tubular organ formation.
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Affiliation(s)
- Thao Phuong Le
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803
| | - SeYeon Chung
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803
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25
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Bhat SA, Yousuf A, Mushtaq Z, Kumar V, Qurashi A. Fragile X Premutation rCGG Repeats Impair Synaptic Growth and Synaptic Transmission at Drosophila larval Neuromuscular Junction. Hum Mol Genet 2021; 30:1677-1692. [PMID: 33772546 DOI: 10.1093/hmg/ddab087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 11/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disease that develops in some premutation (PM) carriers of the FMR1 gene with alleles bearing 55-200 CGG repeats. The discovery of a broad spectrum of clinical and cell developmental abnormalities among PM carriers with or without FXTAS and in model systems suggests that neurodegeneration seen in FXTAS could be the inevitable end-result of pathophysiological processes set during early development. Hence, it is imperative to trace early PM-induced pathological abnormalities. Previous studies have shown that transgenic Drosophila carrying PM-length CGG repeats are sufficient to cause neurodegeneration. Here, we used the same transgenic model to understand the effect of CGG repeats on the structure and function of the developing nervous system. We show that presynaptic expression of CGG repeats restricts synaptic growth, reduces the number of synaptic boutons, leads to aberrant presynaptic varicosities, and impairs synaptic transmission at the larval neuromuscular junctions. The postsynaptic analysis shows that both glutamate receptors and subsynaptic reticulum proteins were normal. However, a high percentage of boutons show a reduced density of Bruchpilot protein, a key component of presynaptic active zones required for vesicle release. The electrophysiological analysis shows a significant reduction in quantal content, a measure of total synaptic vesicles released per excitation potential. Together, these findings suggest that synapse perturbation caused by rCGG repeats mediates presynaptically during larval NMJ development. We also suggest that the stress-activated c-Jun N-terminal kinase protein Basket and CIDE-N protein Drep-2 positively mediate Bruchpilot active zone defects caused by rCGG repeats.
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Affiliation(s)
- Sajad A Bhat
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Aadil Yousuf
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Zeeshan Mushtaq
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Vimlesh Kumar
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Abrar Qurashi
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
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26
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Płochocka AZ, Ramirez Moreno M, Davie AM, Bulgakova NA, Chumakova L. Robustness of the microtubule network self-organization in epithelia. eLife 2021; 10:59529. [PMID: 33522481 PMCID: PMC7920549 DOI: 10.7554/elife.59529] [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: 06/01/2020] [Accepted: 01/26/2021] [Indexed: 12/24/2022] Open
Abstract
Robustness of biological systems is crucial for their survival, however, for many systems its origin is an open question. Here, we analyze one subcellular level system, the microtubule cytoskeleton. Microtubules self-organize into a network, along which cellular components are delivered to their biologically relevant locations. While the dynamics of individual microtubules is sensitive to the organism’s environment and genetics, a similar sensitivity of the overall network would result in pathologies. Our large-scale stochastic simulations show that the self-organization of microtubule networks is robust in a wide parameter range in individual cells. We confirm this robustness in vivo on the tissue-scale using genetic manipulations of Drosophila epithelial cells. Finally, our minimal mathematical model shows that the origin of robustness is the separation of time-scales in microtubule dynamics rates. Altogether, we demonstrate that the tissue-scale self-organization of a microtubule network depends only on cell geometry and the distribution of the microtubule minus-ends.
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Affiliation(s)
| | - Miguel Ramirez Moreno
- Department of Biomedical Science, The University of Sheffield, Sheffield, United Kingdom
| | - Alexander M Davie
- Maxwell Institute for Mathematical Sciences, School of Mathematics, Edinburgh University, Edinburgh, United Kingdom
| | - Natalia A Bulgakova
- Department of Biomedical Science, The University of Sheffield, Sheffield, United Kingdom
| | - Lyubov Chumakova
- Maxwell Institute for Mathematical Sciences, School of Mathematics, Edinburgh University, Edinburgh, United Kingdom
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27
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Vemu A, Szczesna E, Roll-Mecak A. In Vitro Reconstitution Assays of Microtubule Amplification and Lattice Repair by the Microtubule-Severing Enzymes Katanin and Spastin. Methods Mol Biol 2021; 2101:27-38. [PMID: 31879896 DOI: 10.1007/978-1-0716-0219-5_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microtubules are non-covalent dynamic polymers essential for the life of all eukaryotic cells. Their dynamic behavior is regulated by a large array of cellular effectors. In vitro microtubule assays have been instrumental in dissecting the mechanism of microtubule-associated proteins. In this chapter, we focus on microtubule-severing enzymes katanin and spastin. They are AAA ATPases that generate internal breaks in microtubules by extracting tubulin dimers out of the microtubule lattice. We present protocols for TIRF microscopy-based assays that were instrumental in proving that these enzymes not only sever microtubules but also remodel the microtubule lattice by promoting the exchange of lattice GDP-tubulin with GTP-tubulin from the soluble pool. This activity can modulate microtubule dynamics and support microtubule-dependent microtubule amplification in the absence of a nucleating factor.
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Affiliation(s)
- Annapurna Vemu
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ewa Szczesna
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA. .,Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA.
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28
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Impairment of the mitochondrial one-carbon metabolism enzyme SHMT2 causes a novel brain and heart developmental syndrome. Acta Neuropathol 2020; 140:971-975. [PMID: 33015733 PMCID: PMC7665968 DOI: 10.1007/s00401-020-02223-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023]
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29
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Kuo YW, Howard J. Cutting, Amplifying, and Aligning Microtubules with Severing Enzymes. Trends Cell Biol 2020; 31:50-61. [PMID: 33183955 PMCID: PMC7749064 DOI: 10.1016/j.tcb.2020.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 02/08/2023]
Abstract
Microtubule-severing enzymes - katanin, spastin, fidgetin - are related AAA-ATPases that cut microtubules into shorter filaments. These proteins, also called severases, are involved in a wide range of cellular processes including cell division, neuronal development, and tissue morphogenesis. Paradoxically, severases can amplify the microtubule cytoskeleton and not just destroy it. Recent work on spastin and katanin has partially resolved this paradox by showing that these enzymes are strong promoters of microtubule growth. Here, we review recent structural and biophysical advances in understanding the molecular mechanisms of severing and growth promotion that provide insight into how severing enzymes shape microtubule networks.
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Affiliation(s)
- Yin-Wei Kuo
- Department of Chemistry, Yale University, New Haven, CT 06511, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
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30
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Ji ZS, Liu QL, Zhang JF, Yang YH, Li J, Zhang GW, Tan MH, Lin HS, Guo GQ. SUMOylation of spastin promotes the internalization of GluA1 and regulates dendritic spine morphology by targeting microtubule dynamics. Neurobiol Dis 2020; 146:105133. [PMID: 33049318 DOI: 10.1016/j.nbd.2020.105133] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/24/2020] [Accepted: 10/06/2020] [Indexed: 10/23/2022] Open
Abstract
Dendritic spines are specialized structures involved in neuronal processes on which excitatory synaptic contact occurs. The microtubule cytoskeleton is vital for maintaining spine morphology and mature synapses. Spastin is related to microtubule-severing proteases and is involved in synaptic bouton formation. However, it is not yet known if spastin can be modified by Small Ubiquitin-like Modifier (SUMO) or how this modification regulates dendritic spines. Spastin was shown to be SUMOylated at K427, and its deSUMOylation promoted microtubule stability. In addition, SUMOylation of spastin was shown to affect signalling pathways associated with long term synaptic depression. SUMOylated spastin promoted the development of dendrites and dendritic spines. Moreover, SUMOylated spastin regulated endocytosis and affected the transport of the AMPA receptor, GluA1. Our findings suggest that SUMOylation of spastin promotes GluA1 internalization and regulates dendritic spine morphology through targeting of microtubule dynamics.
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Affiliation(s)
- Zhi-Sheng Ji
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Qiu-Ling Liu
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Ji-Feng Zhang
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Yu-Hao Yang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Jiong Li
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Guo-Wei Zhang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Ming-Hui Tan
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
| | - Hong-Sheng Lin
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
| | - Guo-Qing Guo
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
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31
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Sakoe K, Shioda N, Matsuura T. A newly identified NES sequence present in spastin regulates its subcellular localization and microtubule severing activity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118862. [PMID: 32979422 DOI: 10.1016/j.bbamcr.2020.118862] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 09/11/2020] [Accepted: 09/19/2020] [Indexed: 01/01/2023]
Abstract
Spastin, a microtubule-severing AAA ATPase, regulates microtubule dynamics and plays important roles in cell division and neurogenesis. Mutations in the spastin-coding gene SPAST lead to neurodegenerative disorders and cause spastic paraplegia type 4. Spastin has two main isoforms, M1 and M87, that differ only in the presence or absence of 86 N-terminal amino acids and have alternative splicing variants that lack exon4. The N-terminal region of M1 contains a hydrophobic domain, nuclear localization signal (NLS), and nuclear export signal (NES), which partly explains the differences in the two isoforms' localization. However, the mechanisms involved in regulating isoform localization, and the effects of localization on spastin functions are not fully understood. We found endogenous M1 and M87 shuttled between the nucleus and cytoplasm during the cell cycle. We identified a NES (amino acids 195-204) that spans the microtubule-interacting and endosomal-trafficking domain and exon4 region. Furthermore, the NES sequence contains both the coiled-coil and exon4 region of spastin isoforms. Highly conserved leucine 195 in exon3 and the two residues in exon4 are crucial for predicted coiled-coil formation. Mutations in NES or leptomycin B treatment reduced cytoplasmic localization and microtubule fragmentation in M87 rather than in M1. Phosphomimetic mutation of threonine 306 adjacent to the NLS (amino acids 309-312) inhibited nuclear transport of M87. Our results indicate that the newly identified NES in the spastin isoforms containing exon4 regulates the subcellular localization of spastin in coordination with NLS controlled by the phosphorylation state of spastin, and is involved in microtubule severing.
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Affiliation(s)
- Kumi Sakoe
- Division of Neurology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan.
| | - Norifumi Shioda
- Department of Genomic Neurology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Tohru Matsuura
- Division of Neurology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
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32
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Ozdowski EF, Wentzell JS, Engert SM, Abbott H, Sherwood NT. Suppression of spastin Mutant Phenotypes by Pak3 Loss Implicates a Role for Reactive Glia in AD-HSP. Front Neurosci 2020; 14:912. [PMID: 33013303 PMCID: PMC7499821 DOI: 10.3389/fnins.2020.00912] [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: 03/31/2020] [Accepted: 08/06/2020] [Indexed: 11/13/2022] Open
Abstract
Neurodegenerative mechanisms due to mutations in spastin currently center on neuronal defects, primarily in microtubule and endomembrane regulation. Spastin loss in Drosophila larvae compromises neuronal microtubule distribution, alters synaptic bouton morphology, and weakens synaptic transmission at glutamatergic neuromuscular junction (NMJ) synapses. Pak3, a p21-activated kinase that promotes actin polymerization and filopodial projections, is required for these spastin mutant defects; animals lacking both genes have normal NMJs. Here we show that Pak3 is expressed in central and peripheral glial populations, and reduction of Pak3 specifically in subperineurial glial cells is sufficient to suppress the phenotypes associated with spastin loss. Subperineurial glia in the periphery ensheathe motor neuron axons and have been shown to extend actin-based projections that regulate synaptic terminals during normal NMJ development. We find that these subperineurial glial projections are Pak3-dependent and nearly twice as frequent in spastin mutants, while in Pak3, spastin double mutants, neither glial projections nor synaptic defects are observed. Spastin deficiency thus increases Pak3-dependent subperineurial glia activity, which is in turn required for neuronal defects. Our results demonstrate a central role for Pak3-mediated, altered glial behavior in the neuronal defects due to spastin loss, and suggest that a similar reactive glia-mediated mechanism may underlie human AD-HSP pathogenesis.
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Affiliation(s)
| | | | | | | | - Nina T. Sherwood
- Department of Biology, Duke University, Durham, NC, United States
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33
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Lopes AT, Hausrat TJ, Heisler FF, Gromova KV, Lombino FL, Fischer T, Ruschkies L, Breiden P, Thies E, Hermans-Borgmeyer I, Schweizer M, Schwarz JR, Lohr C, Kneussel M. Spastin depletion increases tubulin polyglutamylation and impairs kinesin-mediated neuronal transport, leading to working and associative memory deficits. PLoS Biol 2020; 18:e3000820. [PMID: 32866173 PMCID: PMC7485986 DOI: 10.1371/journal.pbio.3000820] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 09/11/2020] [Accepted: 08/10/2020] [Indexed: 12/21/2022] Open
Abstract
Mutations in the gene encoding the microtubule-severing protein spastin (spastic paraplegia 4 [SPG4]) cause hereditary spastic paraplegia (HSP), associated with neurodegeneration, spasticity, and motor impairment. Complicated forms (complicated HSP [cHSP]) further include cognitive deficits and dementia; however, the etiology and dysfunctional mechanisms of cHSP have remained unknown. Here, we report specific working and associative memory deficits upon spastin depletion in mice. Loss of spastin-mediated severing leads to reduced synapse numbers, accompanied by lower miniature excitatory postsynaptic current (mEPSC) frequencies. At the subcellular level, mutant neurons are characterized by longer microtubules with increased tubulin polyglutamylation levels. Notably, these conditions reduce kinesin-microtubule binding, impair the processivity of kinesin family protein (KIF) 5, and reduce the delivery of presynaptic vesicles and postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Rescue experiments confirm the specificity of these results by showing that wild-type spastin, but not the severing-deficient and disease-associated K388R mutant, normalizes the effects at the synaptic, microtubule, and transport levels. In addition, short hairpin RNA (shRNA)-mediated reduction of tubulin polyglutamylation on spastin knockout background normalizes KIF5 transport deficits and attenuates the loss of excitatory synapses. Our data provide a mechanism that connects spastin dysfunction with the regulation of kinesin-mediated cargo transport, synapse integrity, and cognition. This study identifies deficits in working and associative memory in spastin knockout mice, resembling the cognitive deficits described in humans with severe forms of SPG4-type hereditary spastic paraplegia. Mechanistically, the findings suggest that impaired microtubule growth, kinesin motility and cargo delivery of synaptic AMPA receptors may contribute to the etiology of the disease.
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Affiliation(s)
- André T. Lopes
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Torben J. Hausrat
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Frank F. Heisler
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kira V. Gromova
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Franco L. Lombino
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Timo Fischer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Laura Ruschkies
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Petra Breiden
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Edda Thies
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animal Unit, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michaela Schweizer
- Morphology Unit, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jürgen R. Schwarz
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Matthias Kneussel
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
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34
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Dhanyasi N, VijayRaghavan K, Shilo BZ, Schejter ED. Microtubules provide guidance cues for myofibril and sarcomere assembly and growth. Dev Dyn 2020; 250:60-73. [PMID: 32725855 DOI: 10.1002/dvdy.227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/09/2020] [Accepted: 06/20/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Muscle myofibrils and sarcomeres present exceptional examples of highly ordered cytoskeletal filament arrays, whose distinct spatial organization is an essential aspect of muscle cell functionality. We utilized ultra-structural analysis to investigate the assembly of myofibrils and sarcomeres within developing myotubes of the indirect flight musculature of Drosophila. RESULTS A temporal sequence composed of three major processes was identified: subdivision of the unorganized cytoplasm of nascent, multi-nucleated myotubes into distinct organelle-rich and filament-rich domains; initial organization of the filament-rich domains into myofibrils harboring nascent sarcomeric units; and finally, maturation of the highly-ordered pattern of sarcomeric thick (myosin-based) and thin (microfilament-based) filament arrays in parallel to myofibril radial growth. Significantly, organized microtubule arrays were present throughout these stages and exhibited dynamic changes in their spatial patterns consistent with instructive roles. Genetic manipulations confirm these notions, and imply specific and critical guidance activities of the microtubule-based cytoskeleton, as well as structural interdependence between the myosin- and actin-based filament arrays. CONCLUSIONS Our observations highlight a surprisingly significant, behind-the-scenes role for microtubules in establishment of myofibril and sarcomere spatial patterns and size, and provide a detailed account of the interplay between major cytoskeletal elements in generating these essential contractile myogenic units.
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Affiliation(s)
- Nagaraju Dhanyasi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,National Centre for Biological Sciences, TIFR, Bangalore, India
| | - K VijayRaghavan
- National Centre for Biological Sciences, TIFR, Bangalore, India
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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35
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Tadepalle N, Robers L, Veronese M, Zentis P, Babatz F, Brodesser S, Gruszczyk AV, Schauss A, Höning S, Rugarli EI. Microtubule-dependent and independent roles of spastin in lipid droplet dispersion and biogenesis. Life Sci Alliance 2020; 3:3/6/e202000715. [PMID: 32321733 PMCID: PMC7184029 DOI: 10.26508/lsa.202000715] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/09/2020] [Accepted: 04/14/2020] [Indexed: 12/21/2022] Open
Abstract
Lipid droplets (LDs) are metabolic organelles that store neutral lipids and dynamically respond to changes in energy availability by accumulating or mobilizing triacylglycerols (TAGs). How the plastic behavior of LDs is regulated is poorly understood. Hereditary spastic paraplegia is a central motor axonopathy predominantly caused by mutations in SPAST, encoding the microtubule-severing protein spastin. The spastin-M1 isoform localizes to nascent LDs in mammalian cells; however, the mechanistic significance of this targeting is not fully explained. Here, we show that tightly controlled levels of spastin-M1 are required to inhibit LD biogenesis and TAG accumulation. Spastin-M1 maintains the morphogenesis of the ER when TAG synthesis is prevented, independent from microtubule binding. Moreover, spastin plays a microtubule-dependent role in mediating the dispersion of LDs from the ER upon glucose starvation. Our results reveal a dual role of spastin to shape ER tubules and to regulate LD movement along microtubules, opening new perspectives for the pathogenesis of hereditary spastic paraplegia.
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Affiliation(s)
- Nimesha Tadepalle
- Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Lennart Robers
- Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Matteo Veronese
- Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Peter Zentis
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Felix Babatz
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Susanne Brodesser
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Anja V Gruszczyk
- Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Astrid Schauss
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Stefan Höning
- Institute for Biochemistry I, University of Cologne, Cologne, Germany
| | - Elena I Rugarli
- Institute for Genetics, University of Cologne, Cologne, Germany .,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
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36
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Krude H, Biebermann H, Schuelke M, Müller TD, Tschöp M. Allan-Herndon-Dudley-Syndrome: Considerations about the Brain Phenotype with Implications for Treatment Strategies. Exp Clin Endocrinol Diabetes 2020; 128:414-422. [PMID: 32242326 DOI: 10.1055/a-1108-1456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Despite its first description more than 75 years ago, effective treatment for "Allan-Herndon-Dudley-Syndrome (AHDS)", an X-linked thyroid hormone transporter defect, is unavailable. Mutations in the SLC16A2 gene have been discovered to be causative for AHDS in 2004, but a comprehensive understanding of the function of the encoded protein, monocarboxylate transporter 8 (MCT8), is incomplete. Patients with AHDS suffer from neurodevelopmental delay, as well as extrapyramidal (dystonia, chorea, athetosis), pyramidal (spasticity), and cerebellar symptoms (ataxia). This suggests an affection of the pyramidal tracts, basal ganglia, and cerebellum, most likely already during fetal brain development. The function of other brain areas relevant for mood, behavior, and vigilance seems to be intact. An optimal treatment strategy should thus aim to deliver T3 to these relevant structures at the correct time points during development. A potential therapeutic strategy meeting these needs might be the delivery of T3 via a "Trojan horse mechanism" by which T3 is delivered into target cells by a thyroid hormone transporter independent T3 internalization.
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Affiliation(s)
- Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin, Berlin, Germany
| | - Markus Schuelke
- Department of Neuropediatrics, Charité - Universitätsmedizin, Berlin, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Centre Munich, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
| | - Matthias Tschöp
- Division of Metabolic Diseases, Technische Universität München, Munich, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Helmholtz Zentrum München, Germany
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37
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Abstract
The intracellular transport system in neurons is specialized to an extraordinary degree, enabling the delivery of critical cargo to sites in axons or dendrites that are far removed from the cell center. Vesicles formed in the cell body are actively transported by kinesin motors along axonal microtubules to presynaptic sites that can be located more than a meter away. Both growth factors and degradative vesicles carrying aged organelles or aggregated proteins take the opposite route, driven by dynein motors. Distance is not the only challenge; precise delivery of cargos to sites of need must also be accomplished. For example, localized delivery of presynaptic components to hundreds of thousands of "en passant" synapses distributed along the length of a single axon in some neuronal subtypes provides a layer of complexity that must be successfully navigated to maintain synaptic transmission. We review recent advances in the field of axonal transport, with a focus on conceptual developments, and highlight our growing quantitative understanding of neuronal trafficking and its role in maintaining the synaptic function that underlies higher cognitive processes such as learning and memory.
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Affiliation(s)
- Pedro Guedes-Dias
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Institute of Neuronal Cell Biology, Technische Universität München, 80802 Munich, Germany
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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38
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Singh MD, Jensen M, Lasser M, Huber E, Yusuff T, Pizzo L, Lifschutz B, Desai I, Kubina A, Yennawar S, Kim S, Iyer J, Rincon-Limas DE, Lowery LA, Girirajan S. NCBP2 modulates neurodevelopmental defects of the 3q29 deletion in Drosophila and Xenopus laevis models. PLoS Genet 2020; 16:e1008590. [PMID: 32053595 PMCID: PMC7043793 DOI: 10.1371/journal.pgen.1008590] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/26/2020] [Accepted: 12/30/2019] [Indexed: 12/12/2022] Open
Abstract
The 1.6 Mbp deletion on chromosome 3q29 is associated with a range of neurodevelopmental disorders, including schizophrenia, autism, microcephaly, and intellectual disability. Despite its importance towards neurodevelopment, the role of individual genes, genetic interactions, and disrupted biological mechanisms underlying the deletion have not been thoroughly characterized. Here, we used quantitative methods to assay Drosophila melanogaster and Xenopus laevis models with tissue-specific individual and pairwise knockdown of 14 homologs of genes within the 3q29 region. We identified developmental, cellular, and neuronal phenotypes for multiple homologs of 3q29 genes, potentially due to altered apoptosis and cell cycle mechanisms during development. Using the fly eye, we screened for 314 pairwise knockdowns of homologs of 3q29 genes and identified 44 interactions between pairs of homologs and 34 interactions with other neurodevelopmental genes. Interestingly, NCBP2 homologs in Drosophila (Cbp20) and X. laevis (ncbp2) enhanced the phenotypes of homologs of the other 3q29 genes, leading to significant increases in apoptosis that disrupted cellular organization and brain morphology. These cellular and neuronal defects were rescued with overexpression of the apoptosis inhibitors Diap1 and xiap in both models, suggesting that apoptosis is one of several potential biological mechanisms disrupted by the deletion. NCBP2 was also highly connected to other 3q29 genes in a human brain-specific interaction network, providing support for the relevance of our results towards the human deletion. Overall, our study suggests that NCBP2-mediated genetic interactions within the 3q29 region disrupt apoptosis and cell cycle mechanisms during development. Rare copy-number variants, or large deletions and duplications in the genome, are associated with a wide range of neurodevelopmental disorders. The 3q29 deletion confers an increased risk for schizophrenia and autism. To understand the conserved biological mechanisms that are disrupted by this deletion, we systematically tested 14 individual homologs and 314 pairwise interactions of 3q29 genes for neuronal, cellular, and developmental phenotypes in Drosophila melanogaster and Xenopus laevis models. We found that multiple homologs of genes within the deletion region contribute towards developmental defects, such as larval lethality and disrupted cellular organization. Interestingly, we found that NCBP2 acts as a key modifier gene within the region, enhancing the developmental phenotypes of each of the homologs for other 3q29 genes and leading to disruptions in apoptosis and cell cycle pathways. Our results suggest that multiple genes within the 3q29 region interact with each other through shared mechanisms and jointly contribute to neurodevelopmental defects.
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Affiliation(s)
- Mayanglambam Dhruba Singh
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Matthew Jensen
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Micaela Lasser
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Emily Huber
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Tanzeen Yusuff
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Lucilla Pizzo
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Brian Lifschutz
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Inshya Desai
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alexis Kubina
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Sneha Yennawar
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Sydney Kim
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Janani Iyer
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Diego E Rincon-Limas
- Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Laura Anne Lowery
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
- Department of Medicine, Boston University Medical Center, Boston, Massachusetts, United States of America
| | - Santhosh Girirajan
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania, United States of America
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39
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Öztürk Z, O’Kane CJ, Pérez-Moreno JJ. Axonal Endoplasmic Reticulum Dynamics and Its Roles in Neurodegeneration. Front Neurosci 2020; 14:48. [PMID: 32116502 PMCID: PMC7025499 DOI: 10.3389/fnins.2020.00048] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
The physical continuity of axons over long cellular distances poses challenges for their maintenance. One organelle that faces this challenge is endoplasmic reticulum (ER); unlike other intracellular organelles, this forms a physically continuous network throughout the cell, with a single membrane and a single lumen. In axons, ER is mainly smooth, forming a tubular network with occasional sheets or cisternae and low amounts of rough ER. It has many potential roles: lipid biosynthesis, glucose homeostasis, a Ca2+ store, protein export, and contacting and regulating other organelles. This tubular network structure is determined by ER-shaping proteins, mutations in some of which are causative for neurodegenerative disorders such as hereditary spastic paraplegia (HSP). While axonal ER shares many features with the tubular ER network in other contexts, these features must be adapted to the long and narrow dimensions of axons. ER appears to be physically continuous throughout axons, over distances that are enormous on a subcellular scale. It is therefore a potential channel for long-distance or regional communication within neurons, independent of action potentials or physical transport of cargos, but involving its physiological roles such as Ca2+ or organelle homeostasis. Despite its apparent stability, axonal ER is highly dynamic, showing features like anterograde and retrograde transport, potentially reflecting continuous fusion and breakage of the network. Here we discuss the transport processes that must contribute to this dynamic behavior of ER. We also discuss the model that these processes underpin a homeostatic process that ensures both enough ER to maintain continuity of the network and repair breaks in it, but not too much ER that might disrupt local cellular physiology. Finally, we discuss how failure of ER organization in axons could lead to axon degenerative diseases, and how a requirement for ER continuity could make distal axons most susceptible to degeneration in conditions that disrupt ER continuity.
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Affiliation(s)
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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40
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Chou VT, Johnson S, Long J, Vounatsos M, Van Vactor D. dTACC restricts bouton addition and regulates microtubule organization at the Drosophila neuromuscular junction. Cytoskeleton (Hoboken) 2020; 77:4-15. [PMID: 31702858 PMCID: PMC7027520 DOI: 10.1002/cm.21578] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/11/2019] [Accepted: 11/05/2019] [Indexed: 12/20/2022]
Abstract
Regulation of the synaptic cytoskeleton is essential to proper neuronal development and wiring. Perturbations in neuronal microtubules (MTs) are associated with numerous pathologies, yet it remains unclear how changes in MTs may be coupled to synapse morphogenesis. Studies have identified many MT regulators that promote synapse growth. However, less is known about the factors that restrict growth, despite the potential links of synaptic overgrowth to severe neurological conditions. Here, we report that dTACC, which is implicated in MT assembly and stability, prevents synapse overgrowth at the Drosophila neuromuscular junction by restricting addition of new boutons throughout larval development. dTACC localizes to the axonal MT lattice and is required to maintain tubulin levels and the integrity of higher-order MT structures in motor axon terminals. While previous reports have demonstrated the roles of MT-stabilizing proteins in promoting synapse growth, our findings suggest that in certain contexts, MT stabilization may correlate with restricted growth.
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Affiliation(s)
- Vivian T. Chou
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Seth Johnson
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Jennifer Long
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - Maxime Vounatsos
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
| | - David Van Vactor
- Department of Cell Biology and Program in NeuroscienceBlavatnik Institute, Harvard Medical SchoolBostonMassachusetts
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41
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Vajente N, Norante R, Redolfi N, Daga A, Pizzo P, Pendin D. Microtubules Stabilization by Mutant Spastin Affects ER Morphology and Ca 2+ Handling. Front Physiol 2019; 10:1544. [PMID: 31920731 PMCID: PMC6933510 DOI: 10.3389/fphys.2019.01544] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 12/05/2019] [Indexed: 01/21/2023] Open
Abstract
The endoplasmic reticulum (ER) extends as a network of interconnected tubules and sheet-like structures in eukaryotic cells. ER tubules dynamically change their morphology and position within the cells in response to physiological stimuli and these network rearrangements depend on the microtubule (MT) cytoskeleton. Store-operated calcium entry (SOCE) relies on the repositioning of ER tubules to form specific ER-plasma membrane junctions. Indeed, the tips of polymerizing MTs are supposed to provide the anchor for ER tubules to move toward the plasma membrane, however the precise role of the cytoskeleton during SOCE has not been conclusively clarified. Here we exploit an in vivo approach involving the manipulation of MT dynamics in Drosophila melanogaster by neuronal expression of a dominant-negative variant of the MT-severing protein spastin to induce MT hyper-stabilization. We show that MT stabilization alters ER morphology, favoring an enrichment in ER sheets at the expense of tubules. Stabilizing MTs has a negative impact on the process of SOCE and results in a reduced ER Ca2+ content, affecting the flight ability of the flies. Restoring proper MT organization by administering the MT-destabilizing drug vinblastine, chronically or acutely, rescues ER morphology, SOCE and flight ability, indicating that MT dynamics impairment is responsible for all the phenotypes observed.
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Affiliation(s)
- Nicola Vajente
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Rosa Norante
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Nelly Redolfi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Andrea Daga
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Lecco, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padua, Padua, Italy.,Neuroscience Institute-Italian National Research Council (CNR), Padua, Italy
| | - Diana Pendin
- Department of Biomedical Sciences, University of Padua, Padua, Italy.,Neuroscience Institute-Italian National Research Council (CNR), Padua, Italy
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42
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Qu X, Kumar A, Blockus H, Waites C, Bartolini F. Activity-Dependent Nucleation of Dynamic Microtubules at Presynaptic Boutons Controls Neurotransmission. Curr Biol 2019; 29:4231-4240.e5. [PMID: 31813605 DOI: 10.1016/j.cub.2019.10.049] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/24/2019] [Accepted: 10/24/2019] [Indexed: 11/25/2022]
Abstract
Control of microtubule (MT) nucleation and dynamics is critical for neuronal function. Whether MT nucleation is regulated at presynaptic boutons and influences overall presynaptic activity remains unknown. By visualizing MT plus-end dynamics at individual excitatory en passant boutons in axons of cultured hippocampal neurons and in hippocampal slices expressing EB3-EGFP and vGlut1-mCherry, we found that dynamic MTs preferentially grow from presynaptic boutons, show biased directionality in that they are almost always oriented toward the distal tip of the axon, and can be induced by neuronal activity. Silencing of γ-tubulin expression reduced presynaptic MT nucleation, and depletion of either HAUS1 or HAUS7-augmin subunits increased the percentage of retrograde comets initiated at boutons, indicating that γ-tubulin and augmin are required for activity-dependent de novo nucleation of uniformly distally oriented dynamic MTs. We analyzed the dynamics of a wide range of axonal organelles as well as synaptic vesicles (SVs) relative to vGlut1+ stable presynaptic boutons in a time window during which MT nucleation at boutons is promoted upon induction of neuronal activity, and we found that γ-tubulin-dependent presynaptic MT nucleation controls bidirectional (SV) interbouton transport and regulates evoked SV exocytosis. Hence, en passant boutons act as hotspots for activity-dependent de novo MT nucleation, which controls neurotransmission by providing dynamic tracks for bidirectional delivery of SVs between sites of neurotransmitter release.
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Affiliation(s)
- Xiaoyi Qu
- Department of Pathology & Cell Biology, Columbia University Medical Center, 630 W. 168(th) Street, New York, NY 10032, USA
| | - Atul Kumar
- Department of Pathology & Cell Biology, Columbia University Medical Center, 630 W. 168(th) Street, New York, NY 10032, USA
| | - Heike Blockus
- Department of Neuroscience, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Clarissa Waites
- Department of Pathology & Cell Biology, Columbia University Medical Center, 630 W. 168(th) Street, New York, NY 10032, USA
| | - Francesca Bartolini
- Department of Pathology & Cell Biology, Columbia University Medical Center, 630 W. 168(th) Street, New York, NY 10032, USA.
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43
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Kuo YW, Trottier O, Howard J. Predicted Effects of Severing Enzymes on the Length Distribution and Total Mass of Microtubules. Biophys J 2019; 117:2066-2078. [PMID: 31708162 DOI: 10.1016/j.bpj.2019.10.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 01/12/2023] Open
Abstract
Microtubules are dynamic cytoskeletal polymers whose growth and shrinkage are highly regulated as eukaryotic cells change shape, move, and divide. One family of microtubule regulators includes the ATP-hydrolyzing enzymes spastin, katanin, and fidgetin, which sever microtubule polymers into shorter fragments. Paradoxically, severases can increase microtubule number and mass in cells. Recent work with purified spastin and katanin accounts for this phenotype by showing that, in addition to severing, these enzymes modulate microtubule dynamics by accelerating the conversion of microtubules from their shrinking to their growing states and thereby promoting their regrowth. This leads to the observed exponential increase in microtubule mass. Spastin also influences the steady-state distribution of microtubule lengths, changing it from an exponential, as predicted by models of microtubule dynamic instability, to a peaked distribution. This effect of severing and regrowth by spastin on the microtubule length distribution has not been explained theoretically. To solve this problem, we formulated and solved a master equation for the time evolution of microtubule lengths in the presence of severing and microtubule dynamic instability. We then obtained numerical solutions to the steady-state length distribution and showed that the rate of severing and the speed of microtubule growth are the dominant parameters determining the steady-state length distribution. Furthermore, we found that the amplification rate is predicted to increase with severing, which is, to our knowledge, a new result. Our results establish a theoretical basis for how severing and dynamics together can serve to nucleate new microtubules, constituting a versatile mechanism to regulate microtubule length and mass.
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Affiliation(s)
- Yin-Wei Kuo
- Department of Chemistry, Yale University, New Haven, Connecticut; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Olivier Trottier
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut; Department of Physics, Yale University, New Haven, Connecticut
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.
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44
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Guo H, Bettella E, Marcogliese PC, Zhao R, Andrews JC, Nowakowski TJ, Gillentine MA, Hoekzema K, Wang T, Wu H, Jangam S, Liu C, Ni H, Willemsen MH, van Bon BW, Rinne T, Stevens SJC, Kleefstra T, Brunner HG, Yntema HG, Long M, Zhao W, Hu Z, Colson C, Richard N, Schwartz CE, Romano C, Castiglia L, Bottitta M, Dhar SU, Erwin DJ, Emrick L, Keren B, Afenjar A, Zhu B, Bai B, Stankiewicz P, Herman K, Mercimek-Andrews S, Juusola J, Wilfert AB, Abou Jamra R, Büttner B, Mefford HC, Muir AM, Scheffer IE, Regan BM, Malone S, Gecz J, Cobben J, Weiss MM, Waisfisz Q, Bijlsma EK, Hoffer MJV, Ruivenkamp CAL, Sartori S, Xia F, Rosenfeld JA, Bernier RA, Wangler MF, Yamamoto S, Xia K, Stegmann APA, Bellen HJ, Murgia A, Eichler EE. Disruptive mutations in TANC2 define a neurodevelopmental syndrome associated with psychiatric disorders. Nat Commun 2019; 10:4679. [PMID: 31616000 PMCID: PMC6794285 DOI: 10.1038/s41467-019-12435-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 08/19/2019] [Indexed: 12/31/2022] Open
Abstract
Postsynaptic density (PSD) proteins have been implicated in the pathophysiology of neurodevelopmental and psychiatric disorders. Here, we present detailed clinical and genetic data for 20 patients with likely gene-disrupting mutations in TANC2-whose protein product interacts with multiple PSD proteins. Pediatric patients with disruptive mutations present with autism, intellectual disability, and delayed language and motor development. In addition to a variable degree of epilepsy and facial dysmorphism, we observe a pattern of more complex psychiatric dysfunction or behavioral problems in adult probands or carrier parents. Although this observation requires replication to establish statistical significance, it also suggests that mutations in this gene are associated with a variety of neuropsychiatric disorders consistent with its postsynaptic function. We find that TANC2 is expressed broadly in the human developing brain, especially in excitatory neurons and glial cells, but shows a more restricted pattern in Drosophila glial cells where its disruption affects behavioral outcomes.
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Affiliation(s)
- Hui Guo
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Elisa Bettella
- Laboratory of Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Via Giustiniani 3, 35128, Padua, Italy
- Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Corso Stati Uniti 4, 35129, Padua, Italy
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
| | - Rongjuan Zhao
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Jonathan C Andrews
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
| | - Tomasz J Nowakowski
- UCSF Department of Anatomy, University of California, San Francisco, San Francisco, CA, 94143, USA
- UCSF Department of Psychiatry, University of California, San Francisco, San Francisco, CA, 94143, USA
- UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Madelyn A Gillentine
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Kendra Hoekzema
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Tianyun Wang
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Huidan Wu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Sharayu Jangam
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
| | - Cenying Liu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Hailun Ni
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Marjolein H Willemsen
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Center, 6202 AZ, Maastricht, The Netherlands
| | - Bregje W van Bon
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
| | - Tuula Rinne
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
| | - Servi J C Stevens
- Department of Clinical Genetics, Maastricht University Medical Center, 6202 AZ, Maastricht, The Netherlands
| | - Tjitske Kleefstra
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
| | - Han G Brunner
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Center, 6202 AZ, Maastricht, The Netherlands
| | - Helger G Yntema
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
| | - Min Long
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Wenjing Zhao
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Zhengmao Hu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
| | - Cindy Colson
- Normandie Univ, UNICAEN, CHU de Caen Normandie, Department of Genetics, EA7450 BioTARGen, 14000, Caen, France
| | - Nicolas Richard
- Normandie Univ, UNICAEN, CHU de Caen Normandie, Department of Genetics, EA7450 BioTARGen, 14000, Caen, France
| | | | | | | | | | - Shweta U Dhar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Deanna J Erwin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Lisa Emrick
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Boris Keren
- Département de génétique, Hôpital Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, 75013, Paris, France
| | - Alexandra Afenjar
- APHP, Centre de référence des malformations et maladies congénitales du cervelet Département de génétique et embryologie médicale, GRCn°19, pathologies Congénitales du Cervelet-LeucoDystrophies, AP-HP, Hôpital Armand Trousseau, F-75012, Paris, France
| | - Baosheng Zhu
- Department of Pediatrics, The First People's Hospital of Yunnan Province, 650032, Kunming, Yunnan, China
- Medical Faculty, Kunming University of Science and Technology, 650032, Kunming, Yunnan, China
| | - Bing Bai
- Department of Pediatrics, The First People's Hospital of Yunnan Province, 650032, Kunming, Yunnan, China
- Medical Faculty, Kunming University of Science and Technology, 650032, Kunming, Yunnan, China
| | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kristin Herman
- Section of Medical Genomics, Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Sacramento, CA, 95817, USA
| | - Saadet Mercimek-Andrews
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada
| | | | - Amy B Wilfert
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Benjamin Büttner
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Heather C Mefford
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Alison M Muir
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Ingrid E Scheffer
- Departments of Medicine and Paediatrics, The University of Melbourne, Austin Health and Royal Children's Hospital, Melbourne, VIC, 3084, Australia
| | - Brigid M Regan
- Departments of Medicine and Paediatrics, The University of Melbourne, Austin Health and Royal Children's Hospital, Melbourne, VIC, 3084, Australia
| | - Stephen Malone
- Department of Neurosciences, Queensland Children's Hospital, Brisbane, QLD, 4101, Australia
| | - Jozef Gecz
- School of Medicine and the Robinson Research Institute, The University of Adelaide at the Women's and Children's Hospital, Adelaide, SA, 5006, Australia
| | - Jan Cobben
- Emma Children's Hospital AUMC, 1105 AZ, Amsterdam, The Netherlands
- North West Thames Genetics Service NHS, London, UK
| | - Marjan M Weiss
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Clinical Genetics, Amsterdam, Netherlands
| | - Quinten Waisfisz
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Clinical Genetics, Amsterdam, Netherlands
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Stefano Sartori
- Paediatric Neurology and Neurophysiology Unit, Department of Women's and Children's Health, University Hospital of Padua, 35128, Padua, Italy
| | - Fan Xia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Raphael A Bernier
- Department of Psychiatry, University of Washington, Seattle, WA, 98195, USA
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kun Xia
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 410078, Changsha, Hunan, China
- Hunan Key Laboratory of Animal Models for Human Diseases, 410078, Changsha, Hunan, China
| | - Alexander P A Stegmann
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
- Department of Clinical Genetics, Maastricht University Medical Center, 6202 AZ, Maastricht, The Netherlands
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, 77030, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Alessandra Murgia
- Laboratory of Molecular Genetics of Neurodevelopment, Department of Women's and Children's Health, University of Padua, Via Giustiniani 3, 35128, Padua, Italy.
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA.
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Fowler PC, Garcia-Pardo ME, Simpson JC, O'Sullivan NC. NeurodegenERation: The Central Role for ER Contacts in Neuronal Function and Axonopathy, Lessons From Hereditary Spastic Paraplegias and Related Diseases. Front Neurosci 2019; 13:1051. [PMID: 31680803 PMCID: PMC6801308 DOI: 10.3389/fnins.2019.01051] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/19/2019] [Indexed: 12/17/2022] Open
Abstract
The hereditary spastic paraplegias (HSPs) are a group of inherited neurodegenerative conditions whose characteristic feature is degeneration of the longest axons within the corticospinal tract which leads to progressive spasticity and weakness of the lower limbs. Though highly genetically heterogeneous, the majority of HSP cases are caused by mutations in genes encoding proteins that are responsible for generating and organizing the tubular endoplasmic reticulum (ER). Despite this, the role of the ER within neurons, particularly the long axons affected in HSP, is not well understood. Throughout axons, ER tubules make extensive contacts with other organelles, the cytoskeleton and the plasma membrane. At these ER contacts, protein complexes work in concert to perform specialized functions including organelle shaping, calcium homeostasis and lipid biogenesis, all of which are vital for neuronal survival and may be disrupted by HSP-causing mutations. In this article we summarize the proteins which mediate ER contacts, review the functions these contacts are known to carry out within neurons, and discuss the potential contribution of disruption of ER contacts to axonopathy in HSP.
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Affiliation(s)
- Philippa C Fowler
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - M Elena Garcia-Pardo
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Jeremy C Simpson
- UCD School of Biology and Environmental Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Niamh C O'Sullivan
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
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Chen PY, Tsai YW, Cheng YJ, Giangrande A, Chien CT. Glial response to hypoxia in mutants of NPAS1/3 homolog Trachealess through Wg signaling to modulate synaptic bouton organization. PLoS Genet 2019; 15:e1007980. [PMID: 31381576 PMCID: PMC6695205 DOI: 10.1371/journal.pgen.1007980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 08/15/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022] Open
Abstract
Synaptic structure and activity are sensitive to environmental alterations. Modulation of synaptic morphology and function is often induced by signals from glia. However, the process by which glia mediate synaptic responses to environmental perturbations such as hypoxia remains unknown. Here, we report that, in the mutant for Trachealess (Trh), the Drosophila homolog for NPAS1 and NPAS3, smaller synaptic boutons form clusters named satellite boutons appear at larval neuromuscular junctions (NMJs), which is induced by the reduction of internal oxygen levels due to defective tracheal branches. Thus, the satellite bouton phenotype in the trh mutant is suppressed by hyperoxia, and recapitulated in wild-type larvae raised under hypoxia. We further show that hypoxia-inducible factor (HIF)-1α/Similar (Sima) is critical in mediating hypoxia-induced satellite bouton formation. Sima upregulates the level of the Wnt/Wingless (Wg) signal in glia, leading to reorganized microtubule structures within presynaptic sites. Finally, hypoxia-induced satellite boutons maintain normal synaptic transmission at the NMJs, which is crucial for coordinated larval locomotion.
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Affiliation(s)
- Pei-Yi Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yi-Wei Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Cheng-Ting Chien
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- * E-mail:
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Sandate CR, Szyk A, Zehr EA, Lander GC, Roll-Mecak A. An allosteric network in spastin couples multiple activities required for microtubule severing. Nat Struct Mol Biol 2019; 26:671-678. [PMID: 31285604 PMCID: PMC6761829 DOI: 10.1038/s41594-019-0257-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/24/2019] [Indexed: 12/30/2022]
Abstract
The AAA+ ATPase spastin remodels microtubule arrays through severing and its mutation is the most common cause of hereditary spastic paraplegias (HSP). Polyglutamylation of the tubulin C-terminal tail recruits spastin to microtubules and modulates severing activity. Here, we present a ~3.2 Å resolution cryo-EM structure of the Drosophila melanogaster spastin hexamer with a polyglutamate peptide bound in its central pore. Two electropositive loops arranged in a double-helical staircase coordinate the substrate sidechains. The structure reveals how concurrent nucleotide and substrate binding organizes the conserved spastin pore loops into an ordered network that is allosterically coupled to oligomerization, and suggests how tubulin tail engagement activates spastin for microtubule disassembly. This allosteric coupling may apply generally in organizing AAA+ protein translocases into their active conformations. We show that this allosteric network is essential for severing and is a hotspot for HSP mutations.
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Affiliation(s)
| | - Agnieszka Szyk
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Elena A Zehr
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA.
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48
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Hereditary spastic paraplegia: from diagnosis to emerging therapeutic approaches. Lancet Neurol 2019; 18:1136-1146. [PMID: 31377012 DOI: 10.1016/s1474-4422(19)30235-2] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 12/16/2022]
Abstract
Hereditary spastic paraplegia (HSP) describes a heterogeneous group of genetic neurodegenerative diseases characterised by progressive spasticity of the lower limbs. The pathogenic mechanism, associated clinical features, and imaging abnormalities vary substantially according to the affected gene and differentiating HSP from other genetic diseases associated with spasticity can be challenging. Next generation sequencing-based gene panels are now widely available but have limitations and a molecular diagnosis is not made in most suspected cases. Symptomatic management continues to evolve but with a greater understanding of the pathophysiological basis of individual HSP subtypes there are emerging opportunities to provide targeted molecular therapies and personalised medicine.
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49
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Jeong B, Kim TH, Kim DS, Shin WH, Lee JR, Kim NS, Lee DY. Spastin Contributes to Neural Development through the Regulation of Microtubule Dynamics in the Primary Cilia of Neural Stem Cells. Neuroscience 2019; 411:76-85. [PMID: 31150727 DOI: 10.1016/j.neuroscience.2019.05.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 04/25/2019] [Accepted: 05/12/2019] [Indexed: 11/15/2022]
Abstract
Spastin is a microtubule-severing enzyme encoded by SPAST, which is broadly expressed in various cell types originated from multiple organs. Even though SPAST is well known as a regulator of the axon growth and arborization in neurons and a genetic factor of hereditary spastic paraplegia, it also takes part in a wide range of other cellular functions including the regulation of cell division and proliferation. In this study, we investigated a novel biological role of spastin in developing brain using Spast deficient mouse embryonic neural stem cells (NSCs) and perinatal mouse brain. We found that the expression of spastin begins at early embryonic stages in mouse brain. Using Spast shRNA treated NSCs and mouse brain, we showed that Spast deficiency leads to decrease of NSC proliferation and neuronal lineage differentiation. Finally, we found that spastin controls NSC proliferation by regulating microtubule dynamics in primary cilia. Collectively, these data demonstrate that spastin controls brain development by the regulation of NSC functions at early developmental stages.
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Affiliation(s)
- Bohyeon Jeong
- Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, South Korea
| | - Tae Hwan Kim
- Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Dae-Soo Kim
- Environmental Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea; Department of Bioinformatics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, South Korea
| | - Won-Ho Shin
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon 34114, South Korea
| | - Jae-Ran Lee
- Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea; Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, South Korea
| | - Nam-Soon Kim
- Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, South Korea
| | - Da Yong Lee
- Rare Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, South Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, South Korea.
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50
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Knockdown of the neuronal gene Lim3 at the early stages of development affects mitochondrial function and lifespan in Drosophila. Mech Ageing Dev 2019; 181:29-41. [DOI: 10.1016/j.mad.2019.111121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/29/2019] [Accepted: 05/30/2019] [Indexed: 01/08/2023]
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