1
|
Mendoza CS, Plowinske CR, Montgomery AC, Quinones GB, Banker G, Bentley M. Kinesin Regulation in the Proximal Axon is Essential for Dendrite-selective Transport. Mol Biol Cell 2024; 35:ar81. [PMID: 38598291 DOI: 10.1091/mbc.e23-11-0457] [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] [Indexed: 04/12/2024] Open
Abstract
Neurons are polarized and typically extend multiple dendrites and one axon. To maintain polarity, vesicles carrying dendritic proteins are arrested upon entering the axon. To determine whether kinesin regulation is required for terminating anterograde axonal transport, we overexpressed the dendrite-selective kinesin KIF13A. This caused mistargeting of dendrite-selective vesicles to the axon and a loss of dendritic polarity. Polarity was not disrupted if the kinase MARK2/Par1b was coexpressed. MARK2/Par1b is concentrated in the proximal axon, where it maintains dendritic polarity-likely by phosphorylating S1371 of KIF13A, which lies in a canonical 14-3-3 binding motif. We probed for interactions of KIF13A with 14-3-3 isoforms and found that 14-3-3β and 14-3-3ζ bound KIF13A. Disruption of MARK2 or 14-3-3 activity by small molecule inhibitors caused a loss of dendritic polarity. These data show that kinesin regulation is integral for dendrite-selective transport. We propose a new model in which KIF13A that moves dendrite-selective vesicles in the proximal axon is phosphorylated by MARK2. Phosphorylated KIF13A is then recognized by 14-3-3, which causes dissociation of KIF13A from the vesicle and termination of transport. These findings define a new paradigm for the regulation of vesicle transport by localized kinesin tail phosphorylation, to restrict dendrite-selective vesicles from entering the axon.
Collapse
Affiliation(s)
- Christina S Mendoza
- Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Cameron R Plowinske
- Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Andrew C Montgomery
- Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Geraldine B Quinones
- Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Gary Banker
- Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, Oregon 97239
| | - Marvin Bentley
- Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| |
Collapse
|
2
|
Zhang Y, Lin C. Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow. Curr Opin Cell Biol 2024; 88:102377. [PMID: 38823338 DOI: 10.1016/j.ceb.2024.102377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 05/12/2024] [Accepted: 05/13/2024] [Indexed: 06/03/2024]
Abstract
Nonvesicular lipid transport among different membranes or membrane domains plays crucial roles in lipid homeostasis and organelle biogenesis. However, the forces that drive such lipid transport are not well understood. We propose that lipids tend to flow towards the membrane area with a higher membrane protein density in a process termed lipid osmosis. This process lowers the membrane tension in the area, resulting in a membrane tension difference called osmotic membrane tension. We examine the thermodynamic basis and experimental evidence of lipid osmosis and osmotic membrane tension. We predict that lipid osmosis can drive bulk lipid flows between different membrane regions through lipid transfer proteins, scramblases, or similar barriers that selectively pass lipids but not membrane proteins. We also speculate on the biological functions of lipid osmosis. Finally, we explore other driving forces for lipid transfer and describe potential methods and systems to further test our theory.
Collapse
Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
| | - Chenxiang Lin
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Nanobiology Institute, Yale University, West Haven, CT 06516, USA; Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA.
| |
Collapse
|
3
|
Zhang Y, Lin C. Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574656. [PMID: 38260424 PMCID: PMC10802412 DOI: 10.1101/2024.01.08.574656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Nonvesicular lipid transport among different membranes or membrane domains plays crucial roles in lipid homeostasis and organelle biogenesis. However, the forces that drive such lipid transport are not well understood. We propose that lipids tend to flow towards the membrane area with a higher membrane protein density in a process termed lipid osmosis. This process lowers the membrane tension in the area, resulting in a membrane tension difference called osmotic membrane tension. We examine the thermodynamic basis and experimental evidence of lipid osmosis and osmotic membrane tension. We predict that lipid osmosis can drive bulk lipid flows between different membrane regions through lipid transfer proteins, scramblases, or other similar barriers that selectively pass lipids but not membrane proteins. We also speculate on the biological functions of lipid osmosis. Finally, we explore other driving forces for lipid transfer and describe potential methods and systems to further test our theory.
Collapse
Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Chenxiang Lin
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| |
Collapse
|
4
|
Verma H, Kaur S, Kaur S, Gangwar P, Dhiman M, Mantha AK. Role of Cytoskeletal Elements in Regulation of Synaptic Functions: Implications Toward Alzheimer's Disease and Phytochemicals-Based Interventions. Mol Neurobiol 2024:10.1007/s12035-024-04053-3. [PMID: 38491338 DOI: 10.1007/s12035-024-04053-3] [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: 07/03/2023] [Accepted: 02/13/2024] [Indexed: 03/18/2024]
Abstract
Alzheimer's disease (AD), a multifactorial disease, is characterized by the accumulation of neurofibrillary tangles (NFTs) and amyloid beta (Aβ) plaques. AD is triggered via several factors like alteration in cytoskeletal proteins, a mutation in presenilin 1 (PSEN1), presenilin 2 (PSEN2), amyloid precursor protein (APP), and post-translational modifications (PTMs) in the cytoskeletal elements. Owing to the major structural and functional role of cytoskeletal elements, like the organization of axon initial segmentation, dendritic spines, synaptic regulation, and delivery of cargo at the synapse; modulation of these elements plays an important role in AD pathogenesis; like Tau is a microtubule-associated protein that stabilizes the microtubules, and it also causes inhibition of nucleo-cytoplasmic transportation by disrupting the integrity of nuclear pore complex. One of the major cytoskeletal elements, actin and its dynamics, regulate the dendritic spine structure and functions; impairments have been documented towards learning and memory defects. The second major constituent of these cytoskeletal elements, microtubules, are necessary for the delivery of the cargo, like ion channels and receptors at the synaptic membranes, whereas actin-binding protein, i.e., Cofilin's activation form rod-like structures, is involved in the formation of paired helical filaments (PHFs) observed in AD. Also, the glial cells rely on their cytoskeleton to maintain synaptic functionality. Thus, making cytoskeletal elements and their regulation in synaptic structure and function as an important aspect to be focused for better management and targeting AD pathology. This review advocates exploring phytochemicals and Ayurvedic plant extracts against AD by elucidating their neuroprotective mechanisms involving cytoskeletal modulation and enhancing synaptic plasticity. However, challenges include their limited bioavailability due to the poor solubility and the limited potential to cross the blood-brain barrier (BBB), emphasizing the need for targeted strategies to improve therapeutic efficacy.
Collapse
Affiliation(s)
- Harkomal Verma
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Village Ghudda, VPO - Ghudda, Bathinda, 151 401, Punjab, India
| | - Sharanjot Kaur
- Department of Microbiology, School of Basic Sciences, Central University of Punjab, Village Ghudda, Bathinda, Punjab, India
| | - Sukhchain Kaur
- Department of Microbiology, School of Basic Sciences, Central University of Punjab, Village Ghudda, Bathinda, Punjab, India
| | - Prabhakar Gangwar
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Village Ghudda, VPO - Ghudda, Bathinda, 151 401, Punjab, India
| | - Monisha Dhiman
- Department of Microbiology, School of Basic Sciences, Central University of Punjab, Village Ghudda, Bathinda, Punjab, India
| | - Anil Kumar Mantha
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Village Ghudda, VPO - Ghudda, Bathinda, 151 401, Punjab, India.
| |
Collapse
|
5
|
Zhang W, Fu Y, Peng L, Ogawa Y, Ding X, Rasband A, Zhou X, Shelly M, Rasband MN, Zou P. Immunoproximity biotinylation reveals the axon initial segment proteome. Nat Commun 2023; 14:8201. [PMID: 38081810 PMCID: PMC10713531 DOI: 10.1038/s41467-023-44015-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
The axon initial segment (AIS) is a specialized neuronal compartment required for action potential generation and neuronal polarity. However, understanding the mechanisms regulating AIS structure and function has been hindered by an incomplete knowledge of its molecular composition. Here, using immuno-proximity biotinylation we further define the AIS proteome and its dynamic changes during neuronal maturation. Among the many AIS proteins identified, we show that SCRIB is highly enriched in the AIS both in vitro and in vivo, and exhibits a periodic architecture like the axonal spectrin-based cytoskeleton. We find that ankyrinG interacts with and recruits SCRIB to the AIS. However, loss of SCRIB has no effect on ankyrinG. This powerful and flexible approach further defines the AIS proteome and provides a rich resource to elucidate the mechanisms regulating AIS structure and function.
Collapse
Affiliation(s)
- Wei Zhang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies, PKU-Tsinghua Center for Life Science, Peking University, Beijing, 100871, China
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Yu Fu
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Luxin Peng
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Yuki Ogawa
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Xiaoyun Ding
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Anne Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Xinyue Zhou
- Academy for Advanced Interdisciplinary Studies, PKU-Tsinghua Center for Life Science, Peking University, Beijing, 100871, China
| | - Maya Shelly
- Department of Neurobiology and Behavior, Stony Brook University, New York, NY, USA
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.
- Academy for Advanced Interdisciplinary Studies, PKU-Tsinghua Center for Life Science, Peking University, Beijing, 100871, China.
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
- Chinese Institute for Brain Research (CIBR), Beijing, 102206, China.
| |
Collapse
|
6
|
Banerjee T, Matsuoka S, Biswas D, Miao Y, Pal DS, Kamimura Y, Ueda M, Devreotes PN, Iglesias PA. A dynamic partitioning mechanism polarizes membrane protein distribution. Nat Commun 2023; 14:7909. [PMID: 38036511 PMCID: PMC10689845 DOI: 10.1038/s41467-023-43615-2] [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: 02/24/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
The plasma membrane is widely regarded as the hub of the numerous signal transduction activities. Yet, the fundamental biophysical mechanisms that spatiotemporally compartmentalize different classes of membrane proteins remain unclear. Using multimodal live-cell imaging, here we first show that several lipid-anchored membrane proteins are consistently depleted from the membrane regions where the Ras/PI3K/Akt/F-actin network is activated. The dynamic polarization of these proteins does not depend upon the F-actin-based cytoskeletal structures, recurring shuttling between membrane and cytosol, or directed vesicular trafficking. Photoconversion microscopy and single-molecule measurements demonstrate that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane which enable their selective segregation. When these diffusion coefficients are incorporated into an excitable network-based stochastic reaction-diffusion model, simulations reveal that the altered affinity mediated selective partitioning is sufficient to drive familiar propagating wave patterns. Furthermore, normally uniform integral and lipid-anchored membrane proteins partition successfully when membrane domain-specific peptides are optogenetically recruited to them. We propose "dynamic partitioning" as a new mechanism that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins during various physiological processes where membrane polarizes.
Collapse
Affiliation(s)
- Tatsat Banerjee
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA.
| | - Satomi Matsuoka
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
- Laboratory of Single Molecule Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Debojyoti Biswas
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Yuchuan Miao
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Dhiman Sankar Pal
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Yoichiro Kamimura
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
| | - Masahiro Ueda
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
- Laboratory of Single Molecule Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Peter N Devreotes
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Pablo A Iglesias
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA.
| |
Collapse
|
7
|
Mitchell JW, Midillioglu I, Schauer E, Wang B, Han C, Wildonger J. Coordination of Pickpocket ion channel delivery and dendrite growth in Drosophila sensory neurons. PLoS Genet 2023; 19:e1011025. [PMID: 37943859 PMCID: PMC10662761 DOI: 10.1371/journal.pgen.1011025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/21/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Sensory neurons enable an organism to perceive external stimuli, which is essential for survival. The sensory capacity of a neuron depends on the elaboration of its dendritic arbor and the localization of sensory ion channels to the dendritic membrane. However, it is not well understood when and how ion channels localize to growing sensory dendrites and whether their delivery is coordinated with growth of the dendritic arbor. We investigated the localization of the DEG/ENaC/ASIC ion channel Pickpocket (Ppk) in the peripheral sensory neurons of developing fruit flies. We used CRISPR-Cas9 genome engineering approaches to tag endogenous Ppk1 and visualize it live, including monitoring Ppk1 membrane localization via a novel secreted split-GFP approach. Fluorescently tagged endogenous Ppk1 localizes to dendrites, as previously reported, and, unexpectedly, to axons and axon terminals. In dendrites, Ppk1 is present throughout actively growing dendrite branches and is stably integrated into the neuronal cell membrane during the expansive growth of the arbor. Although Ppk channels are dispensable for dendrite growth, we found that an over-active channel mutant severely reduces dendrite growth, likely by acting at an internal membrane and not the dendritic membrane. Our data reveal that the molecular motor dynein and recycling endosome GTPase Rab11 are needed for the proper trafficking of Ppk1 to dendrites. Based on our data, we propose that Ppk channel transport is coordinated with dendrite morphogenesis, which ensures proper ion channel density and distribution in sensory dendrites.
Collapse
Affiliation(s)
- Josephine W. Mitchell
- Integrated Program in Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, Michigan, United States of America
| | - Ipek Midillioglu
- Pediatrics, University of California, San Diego, La Jolla, California, United States of America
| | - Ethan Schauer
- Pediatrics, University of California, San Diego, La Jolla, California, United States of America
| | - Bei Wang
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Chun Han
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Jill Wildonger
- Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Pediatrics, University of California, San Diego, La Jolla, California, United States of America
- Cell & Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
| |
Collapse
|
8
|
Fréal A, Jamann N, Ten Bos J, Jansen J, Petersen N, Ligthart T, Hoogenraad CC, Kole MH. Sodium channel endocytosis drives axon initial segment plasticity. SCIENCE ADVANCES 2023; 9:eadf3885. [PMID: 37713493 PMCID: PMC10881073 DOI: 10.1126/sciadv.adf3885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 08/15/2023] [Indexed: 09/17/2023]
Abstract
Activity-dependent plasticity of the axon initial segment (AIS) endows neurons with the ability to adapt action potential output to changes in network activity. Action potential initiation at the AIS highly depends on the clustering of voltage-gated sodium channels, but the molecular mechanisms regulating their plasticity remain largely unknown. Here, we developed genetic tools to label endogenous sodium channels and their scaffolding protein, to reveal their nanoscale organization and longitudinally image AIS plasticity in hippocampal neurons in slices and primary cultures. We find that N-methyl-d-aspartate receptor activation causes both long-term synaptic depression and rapid internalization of AIS sodium channels within minutes. The clathrin-mediated endocytosis of sodium channels at the distal AIS increases the threshold for action potential generation. These data reveal a fundamental mechanism for rapid activity-dependent AIS reorganization and suggests that plasticity of intrinsic excitability shares conserved features with synaptic plasticity.
Collapse
Affiliation(s)
- Amélie Fréal
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Nora Jamann
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Jolijn Ten Bos
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Jacqueline Jansen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Naomi Petersen
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Thijmen Ligthart
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Casper C. Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
- Department of Neuroscience, Genentech Inc, South San Francisco, CA, USA
| | - Maarten H. P. Kole
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| |
Collapse
|
9
|
Best MN, Lim Y, Ferenc NN, Kim N, Min L, Wang DB, Sharifi K, Wasserman AE, McTavish SA, Siller KH, Jones MK, Jenkins PM, Mandell JW, Bloom GS. Extracellular Tau Oligomers Damage the Axon Initial Segment. J Alzheimers Dis 2023:JAD221284. [PMID: 37182881 DOI: 10.3233/jad-221284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
BACKGROUND In Alzheimer's disease (AD) brain, neuronal polarity and synaptic connectivity are compromised. A key structure for regulating polarity and functions of neurons is the axon initial segment (AIS), which segregates somatodendritic from axonal proteins and initiates action potentials. Toxic tau species, including extracellular oligomers (xcTauOs), spread tau pathology from neuron to neuron by a prion-like process, but few other cell biological effects of xcTauOs have been described. OBJECTIVE Test the hypothesis that AIS structure is sensitive to xcTauOs. METHODS Cultured wild type (WT) and tau knockout (KO) mouse cortical neurons were exposed to xcTauOs, and quantitative western blotting and immunofluorescence microscopy with anti-TRIM46 monitored effects on the AIS. The same methods were used to compare TRIM46 and two other resident AIS proteins in human hippocampal tissue obtained from AD and age-matched non-AD donors. RESULTS Without affecting total TRIM46 levels, xcTauOs reduce the concentration of TRIM46 within the AIS and cause AIS shortening in cultured WT, but not TKO neurons. Lentiviral-driven tau expression in tau KO neurons rescues AIS length sensitivity to xcTauOs. In human AD hippocampus, the overall protein levels of multiple resident AIS proteins are unchanged compared to non-AD brain, but TRIM46 concentration within the AIS and AIS length are reduced in neurons containing neurofibrillary tangles. CONCLUSION xcTauOs cause partial AIS damage in cultured neurons by a mechanism dependent on intracellular tau, thereby raising the possibility that the observed AIS reduction in AD neurons in vivo is caused by xcTauOs working in concert with endogenous neuronal tau.
Collapse
Affiliation(s)
- Merci N Best
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Yunu Lim
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nina N Ferenc
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nayoung Kim
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Lia Min
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Dora Bigler Wang
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Kamyar Sharifi
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Anna E Wasserman
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Sloane A McTavish
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Karsten H Siller
- Research Computing, University of Virginia, Charlottesville, VA, USA
| | - Marieke K Jones
- Claude Moore Health Sciences Library, University of Virginia, Charlottesville, VA, USA
| | - Paul M Jenkins
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Psychiatry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - James W Mandell
- Department of Pathology, University of Virginia, Charlottesville, VA, USA
| | - George S Bloom
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia, Charlottesville, VA, USA
| |
Collapse
|
10
|
Yonemura Y, Sakai Y, Nakata R, Hagita-Tatsumoto A, Miyasaka T, Misonou H. Active Transport by Cytoplasmic Dynein Maintains the Localization of MAP2 in Developing Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538370. [PMID: 37163107 PMCID: PMC10168327 DOI: 10.1101/2023.04.26.538370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
MAP2 has been widely used as a marker of neuronal dendrites because of its extensive restriction in the somatodendritic region of neurons. Despite that, how the precise localization of such a soluble protein is established and maintained against thermal forces and diffusion has been elusive and long remained a mystery in neuroscience. In this study, we aimed to uncover the mechanism behind how MAP2 is retained in the somatodendritic region. Using GFP-tagged MAP2 expressed in cultured hippocampal neurons, we discovered a crucial protein region responsible for the localization of MAP2, the serine/proline-rich (S/P) region. Our pulse-chase live-cell imaging revealed the slow but steady migration of MAP2 toward distal dendrites, which was not observed in a MAP2 mutant lacking the S/P region, indicating that S/P-dependent transport is vital for the proper localization of MAP2. Furthermore, our experiments using an inhibitor of cytoplasmic Dynein, ciliobrevin D, as well as Dynein knockdown, showed that cytoplasmic Dynein is involved in the transport of MAP2 in dendrites. We also found that Dynein complex binds to MAP2 through the S/P region in heterologous cells. Using mathematical modeling based on experimental data, we confirmed that an intermittent active transport mechanism is essential. Thus, we propose that the cytoplasmic Dynein recruits and transports free MAP2 toward distal dendrites, thereby maintaining the precise dendritic localization of MAP2 in neurons. Our findings shed light on the previously unknown mechanism behind MAP2 localization and provide a new direction for soluble protein trafficking research in the field of cell biology of neurons.
Collapse
|
11
|
Banerjee T, Matsuoka S, Biswas D, Miao Y, Pal DS, Kamimura Y, Ueda M, Devreotes PN, Iglesias PA. A dynamic partitioning mechanism polarizes membrane protein distribution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.03.522496. [PMID: 36712016 PMCID: PMC9881856 DOI: 10.1101/2023.01.03.522496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The plasma membrane is widely regarded as the hub of the signal transduction network activities that drives numerous physiological responses, including cell polarity and migration. Yet, the symmetry breaking process in the membrane, that leads to dynamic compartmentalization of different proteins, remains poorly understood. Using multimodal live-cell imaging, here we first show that multiple endogenous and synthetic lipid-anchored proteins, despite maintaining stable tight association with the inner leaflet of the plasma membrane, were unexpectedly depleted from the membrane domains where the signaling network was spontaneously activated such as in the new protrusions as well as within the propagating ventral waves. Although their asymmetric patterns resembled those of standard peripheral "back" proteins such as PTEN, unlike the latter, these lipidated proteins did not dissociate from the membrane upon global receptor activation. Our experiments not only discounted the possibility of recurrent reversible translocation from membrane to cytosol as it occurs for weakly bound peripheral membrane proteins, but also ruled out the necessity of directed vesicular trafficking and cytoskeletal supramolecular structure-based restrictions in driving these dynamic symmetry breaking events. Selective photoconversion-based protein tracking assays suggested that these asymmetric patterns instead originate from the inherent ability of these membrane proteins to "dynamically partition" into distinct domains within the plane of the membrane. Consistently, single-molecule measurements showed that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane. When these profiles were incorporated into an excitable network-based stochastic reaction-diffusion model of the system, simulations revealed that our proposed "dynamic partitioning" mechanism is sufficient to give rise to familiar asymmetric propagating wave patterns. Moreover, we demonstrated that normally uniform integral and lipid-anchored membrane proteins in Dictyostelium and mammalian neutrophil cells can be induced to partition spatiotemporally to form polarized patterns, by optogenetically recruiting membrane domain-specific peptides to these proteins. Together, our results indicate "dynamic partitioning" as a new mechanism of plasma membrane organization, that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins in different physiological processes.
Collapse
|
12
|
Teliska LH, Dalla Costa I, Sert O, Twiss JL, Rasband MN. Axon Initial Segments Are Required for Efficient Motor Neuron Axon Regeneration and Functional Recovery of Synapses. J Neurosci 2022; 42:8054-8065. [PMID: 36096668 PMCID: PMC9636994 DOI: 10.1523/jneurosci.1261-22.2022] [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: 06/27/2022] [Accepted: 08/02/2022] [Indexed: 11/21/2022] Open
Abstract
The axon initial segment (AIS) generates action potentials and maintains neuronal polarity by regulating the differential trafficking and distribution of proteins, transport vesicles, and organelles. Injury and disease can disrupt the AIS, and the subsequent loss of clustered ion channels and polarity mechanisms may alter neuronal excitability and function. However, the impact of AIS disruption on axon regeneration after injury is unknown. We generated male and female mice with AIS-deficient multipolar motor neurons by deleting AnkyrinG, the master scaffolding protein required for AIS assembly and maintenance. We found that after nerve crush, neuromuscular junction reinnervation was significantly delayed in AIS-deficient motor neurons compared with control mice. In contrast, loss of AnkyrinG from pseudo-unipolar sensory neurons did not impair axon regeneration into the intraepidermal nerve fiber layer. Even after AIS-deficient motor neurons reinnervated the neuromuscular junction, they failed to functionally recover because of reduced synaptic vesicle protein 2 at presynaptic terminals. In addition, mRNA trafficking was disrupted in AIS-deficient axons. Our results show that, after nerve injury, an intact AIS is essential for efficient regeneration and functional recovery of axons in multipolar motor neurons. Our results also suggest that loss of polarity in AIS-deficient motor neurons impairs the delivery of axonal proteins, mRNAs, and other cargoes necessary for regeneration. Thus, therapeutic strategies for axon regeneration must consider preservation or reassembly of the AIS.SIGNIFICANCE STATEMENT Disruption of the axon initial segment is a common event after nervous system injury. For multipolar motor neurons, we show that axon initial segments are essential for axon regeneration and functional recovery after injury. Our results may help explain injuries where axon regeneration fails, and suggest strategies to promote more efficient axon regeneration.
Collapse
Affiliation(s)
- Lindsay H Teliska
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Irene Dalla Costa
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208
| | - Ozlem Sert
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| |
Collapse
|
13
|
Endocytosis in the axon initial segment maintains neuronal polarity. Nature 2022; 609:128-135. [PMID: 35978188 PMCID: PMC9433327 DOI: 10.1038/s41586-022-05074-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/05/2022] [Indexed: 11/09/2022]
Abstract
Neurons are highly polarized cells that face the fundamental challenge of compartmentalizing a vast and diverse repertoire of proteins in order to function properly1. The axon initial segment (AIS) is a specialized domain that separates a neuron’s morphologically, biochemically and functionally distinct axon and dendrite compartments2,3. How the AIS maintains polarity between these compartments is not fully understood. Here we find that in Caenorhabditis elegans, mouse, rat and human neurons, dendritically and axonally polarized transmembrane proteins are recognized by endocytic machinery in the AIS, robustly endocytosed and targeted to late endosomes for degradation. Forcing receptor interaction with the AIS master organizer, ankyrinG, antagonizes receptor endocytosis in the AIS, causes receptor accumulation in the AIS, and leads to polarity deficits with subsequent morphological and behavioural defects. Therefore, endocytic removal of polarized receptors that diffuse into the AIS serves as a membrane-clearance mechanism that is likely to work in conjunction with the known AIS diffusion-barrier mechanism to maintain neuronal polarity on the plasma membrane. Our results reveal a conserved endocytic clearance mechanism in the AIS to maintain neuronal polarity by reinforcing axonal and dendritic compartment membrane boundaries. Endocytosis and degradation of plasma membrane proteins in the axon initial segment, together with the diffusion-barrier mechanism, maintain a polarized distribution of plasma membrane proteins in Caenorhabditis elegans, mouse, rat and human neurons.
Collapse
|
14
|
Thyagarajan P, Feng C, Lee D, Shorey M, Rolls MM. Microtubule polarity is instructive for many aspects of neuronal polarity. Dev Biol 2022; 486:56-70. [PMID: 35341730 PMCID: PMC9058238 DOI: 10.1016/j.ydbio.2022.03.009] [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: 11/29/2021] [Revised: 03/04/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022]
Abstract
Many neurons in bilaterian animals are polarized with functionally distinct axons and dendrites. Microtubule polarity, microtubule stability, and the axon initial segment (AIS) have all been shown to influence polarized transport in neurons. Each of these cytoskeletal cues could act independently to control axon and dendrite identity, or there could be a hierarchy in which one acts upstream of the others. Here we test the hypothesis that microtubule polarity acts as a master regulator of neuronal polarity by using a Drosophila genetic background in which some dendrites have normal minus-end-out microtubule polarity and others have the axonal plus-end-out polarity. In these mosaic dendrite arbors, we found that ribosomes, which are more abundant in dendrites than axons, were reduced in plus-end-out dendrites, while an axonal cargo was increased. In addition, we determined that microtubule stability was different in plus-end-out and minus-end-out dendrites, with plus-end-out ones having more stable microtubules like axons. Similarly, we found that ectopic diffusion barriers, like those at the AIS, formed at the base of dendrites with plus-end-out regions. Thus, changes in microtubule polarity were sufficient to rearrange other cytoskeletal features associated with neuronal polarization. However, overall neuron shape was maintained with only subtle changes in branching in mosaic arbors. We conclude that microtubule polarity can act upstream of many aspects of intracellular neuronal polarization, but shape is relatively resilient to changes in microtubule polarity in vivo.
Collapse
Affiliation(s)
- Pankajam Thyagarajan
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chengye Feng
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - David Lee
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Matthew Shorey
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
| |
Collapse
|
15
|
Yap CC, Winckler B. Spatial regulation of endosomes in growing dendrites. Dev Biol 2022; 486:5-14. [PMID: 35306006 PMCID: PMC10646839 DOI: 10.1016/j.ydbio.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 02/21/2022] [Accepted: 03/13/2022] [Indexed: 01/19/2023]
Abstract
Many membrane proteins are highly enriched in either dendrites or axons. This non-uniform distribution is a critical feature of neuronal polarity and underlies neuronal function. The molecular mechanisms responsible for polarized distribution of membrane proteins has been studied for some time and many answers have emerged. A less well studied feature of neurons is that organelles are also frequently non-uniformly distributed. For instance, EEA1-positive early endosomes are somatodendritic whereas synaptic vesicles are axonal. In addition, some organelles are present in both axons and dendrites, but not distributed uniformly along the processes. One well known example are lysosomes which are abundant in the soma and proximal dendrite, but sparse in the distal dendrite and the distal axon. The mechanisms that determine the spatial distribution of organelles along dendrites are only starting to be studied. In this review, we will discuss the cell biological mechanisms of how the distribution of diverse sets of endosomes along the proximal-distal axis of dendrites might be regulated. In particular, we will focus on the regulation of bulk homeostatic mechanisms as opposed to local regulation. We posit that immature dendrites regulate organelle motility differently from mature dendrites in order to spatially organize dendrite growth, branching and sculpting.
Collapse
|
16
|
Eichel K, Shen K. The function of the axon initial segment in neuronal polarity. Dev Biol 2022; 489:47-54. [DOI: 10.1016/j.ydbio.2022.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 11/25/2022]
|
17
|
Wang Y, Guan M, Zhang Y, Zhanghao K, Xi P. Glucose increases the length and spacing of the lattice structure of the axon initial segment. Microsc Res Tech 2022; 85:2679-2691. [PMID: 35411984 DOI: 10.1002/jemt.24122] [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: 11/29/2021] [Revised: 03/01/2022] [Accepted: 03/31/2022] [Indexed: 11/12/2022]
Abstract
The axon initial segment (AIS) plays an important role in maintaining neuronal polarity and initiating action potentials (APs). The AIS adapts to its environment by changing its length and distance from the cell body, resulting in modulation of neuronal excitability, which is referred to as AIS plasticity. Previous studies found an ~200 nm single periodic distribution of the key AIS components ankyrinG (AnkG), Nav 1.2, and βIV-spectrin, while it remains unclear how the lattice structure is altered by AIS plasticity. In this study, we found that the length of the AIS significantly increased, resulting in increased neuronal excitability, with high-concentration glucose treatment. Structured illumination microscopy (SIM) images of the lattice structure showed a dual-spacing periodic distribution (~200 nm and ~260 nm) of AnkG, Nav 1.2, and βIV-spectrin. Moreover, 480-kDa AnkG was crucial for AIS plasticity and increased lattice structure spacing. The discovery of new regulators for modulating AIS plasticity will help us to understand and manipulate the structure and function of the AIS.
Collapse
Affiliation(s)
- Yiming Wang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, China
| | - Meiling Guan
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing, China
| | - Yan Zhang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Karl Zhanghao
- UTS-SUStech Joint Research Centre for Biomedical Materials & Devices, Department of Biomedical Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Peng Xi
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing, China.,UTS-SUStech Joint Research Centre for Biomedical Materials & Devices, Department of Biomedical Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.,National Biomedical Imaging Center, Peking University, Beijing, China
| |
Collapse
|
18
|
Peña-Ortega F, Robles-Gómez ÁA, Xolalpa-Cueva L. Microtubules as Regulators of Neural Network Shape and Function: Focus on Excitability, Plasticity and Memory. Cells 2022; 11:cells11060923. [PMID: 35326374 PMCID: PMC8946818 DOI: 10.3390/cells11060923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 02/09/2022] [Accepted: 02/17/2022] [Indexed: 12/19/2022] Open
Abstract
Neuronal microtubules (MTs) are complex cytoskeletal protein arrays that undergo activity-dependent changes in their structure and function as a response to physiological demands throughout the lifespan of neurons. Many factors shape the allostatic dynamics of MTs and tubulin dimers in the cytosolic microenvironment, such as protein–protein interactions and activity-dependent shifts in these interactions that are responsible for their plastic capabilities. Recently, several findings have reinforced the role of MTs in behavioral and cognitive processes in normal and pathological conditions. In this review, we summarize the bidirectional relationships between MTs dynamics, neuronal processes, and brain and behavioral states. The outcomes of manipulating the dynamicity of MTs by genetic or pharmacological approaches on neuronal morphology, intrinsic and synaptic excitability, the state of the network, and behaviors are heterogeneous. We discuss the critical position of MTs as responders and adaptative elements of basic neuronal function whose impact on brain function is not fully understood, and we highlight the dilemma of artificially modulating MT dynamics for therapeutic purposes.
Collapse
|
19
|
Puza S, Caesar S, Poojari C, Jung M, Seemann R, Hub JS, Schrul B, Fleury JB. Lipid Droplets Embedded in a Model Cell Membrane Create a Phospholipid Diffusion Barrier. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106524. [PMID: 35072348 DOI: 10.1002/smll.202106524] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Lipid droplets (LDs) are ubiquitous, cytoplasmic fat storage organelles that originate from the endoplasmic reticulum (ER) membrane. They are composed of a core of neutral lipids surrounded by a phospholipid monolayer. Proteins embedded into this monolayer membrane adopt a monotopic topology and are crucial for regulated lipid storage and consumption. A key question is, which collective properties of protein-intrinsic and lipid-mediated features determine spatio-temporal protein partitioning between phospholipid bilayer and LD monolayer membranes. To address this question, a freestanding phospholipid bilayer with physiological lipidic composition is produced using microfluidics and micrometer-sized LDs are dispersed around the bilayer that spontaneously insert into the bilayer. Using confocal microscopy, the 3D geometry of the reconstituted LDs is determined with high spatial resolution. The micrometer-sized bilayer-embedded LDs present a characteristic lens shape that obeys predictions from equilibrium wetting theory. Fluorescence recovery after photobleaching measurements reveals the existence of a phospholipid diffusion barrier at the monolayer-bilayer interface. Coarse-grained molecular dynamics simulation reveals lipid specific density distributions along the pore rim, which may rationalize the diffusion barrier. The lipid diffusion barrier between the LD covering monolayer and the bilayer may be a key phenomenon influencing protein partitioning between the ER membrane and LDs in living cells.
Collapse
Affiliation(s)
- Sevde Puza
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Stefanie Caesar
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg, Germany
| | - Chetan Poojari
- Saarland University, Theoretical Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Michael Jung
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Ralf Seemann
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Jochen S Hub
- Saarland University, Theoretical Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| | - Bianca Schrul
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg, Germany
| | - Jean-Baptiste Fleury
- Saarland University, Experimental Physics and Center for Biophysics (ZBP), Saarland University, 66123, Saarbrücken, Germany
| |
Collapse
|
20
|
Tjiang N, Zempel H. A mitochondria cluster at the proximal axon initial segment controls axodendritic TAU trafficking in rodent primary and human iPSC-derived neurons. Cell Mol Life Sci 2022; 79:120. [PMID: 35119496 PMCID: PMC8816743 DOI: 10.1007/s00018-022-04150-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 12/30/2021] [Accepted: 01/14/2022] [Indexed: 12/23/2022]
Abstract
Loss of neuronal polarity and missorting of the axonal microtubule-associated-protein TAU are hallmarks of Alzheimer’s disease (AD) and related tauopathies. Impairment of mitochondrial function is causative for various mitochondriopathies, but the role of mitochondria in tauopathies and in axonal TAU-sorting is unclear. The axon-initial-segment (AIS) is vital for maintaining neuronal polarity, action potential generation, and—here important—TAU-sorting. Here, we investigate the role of mitochondria in the AIS for maintenance of TAU cellular polarity. Using not only global and local mitochondria impairment via inhibitors of the respiratory chain and a locally activatable protonophore/uncoupler, but also live-cell-imaging and photoconversion methods, we specifically tracked and selectively impaired mitochondria in the AIS in primary mouse and human iPSC-derived forebrain/cortical neurons, and assessed somatic presence of TAU. Global application of mitochondrial toxins efficiently induced tauopathy-like TAU-missorting, indicating involvement of mitochondria in TAU-polarity. Mitochondria show a biased distribution within the AIS, with a proximal cluster and relative absence in the central AIS. The mitochondria of this cluster are largely immobile and only sparsely participate in axonal mitochondria-trafficking. Locally constricted impairment of the AIS-mitochondria-cluster leads to detectable increases of somatic TAU, reminiscent of AD-like TAU-missorting. Mechanistically, mitochondrial impairment sufficient to induce TAU-missorting results in decreases of calcium oscillation but increases in baseline calcium, yet chelating intracellular calcium did not prevent mitochondrial impairment-induced TAU-missorting. Stabilizing microtubules via taxol prevented TAU-missorting, hinting towards a role for impaired microtubule dynamics in mitochondrial-dysfunction-induced TAU-missorting. We provide evidence that the mitochondrial distribution within the proximal axon is biased towards the proximal AIS and that proper function of this newly described mitochondrial cluster may be essential for the maintenance of TAU polarity. Mitochondrial impairment may be an upstream event in and therapeutic target for AD/tauopathy.
Collapse
Affiliation(s)
- Noah Tjiang
- Institute of Human Genetics, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931, Cologne, Germany
| | - Hans Zempel
- Institute of Human Genetics, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931, Cologne, Germany. .,Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931, Cologne, Germany.
| |
Collapse
|
21
|
Zhang W, Ciorraga M, Mendez P, Retana D, Boumedine-Guignon N, Achón B, Russier M, Debanne D, Garrido JJ. Formin Activity and mDia1 Contribute to Maintain Axon Initial Segment Composition and Structure. Mol Neurobiol 2021; 58:6153-6169. [PMID: 34458961 PMCID: PMC8639558 DOI: 10.1007/s12035-021-02531-6] [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: 06/04/2021] [Accepted: 08/11/2021] [Indexed: 10/29/2022]
Abstract
The axon initial segment (AIS) is essential for maintaining neuronal polarity, modulating protein transport into the axon, and action potential generation. These functions are supported by a distinctive actin and microtubule cytoskeleton that controls axonal trafficking and maintains a high density of voltage-gated ion channels linked by scaffold proteins to the AIS cytoskeleton. However, our knowledge of the mechanisms and proteins involved in AIS cytoskeleton regulation to maintain or modulate AIS structure is limited. In this context, formins play a significant role in the modulation of actin and microtubules. We show that pharmacological inhibition of formins modifies AIS actin and microtubule characteristics in cultured hippocampal neurons, reducing F-actin density and decreasing microtubule acetylation. Moreover, formin inhibition diminishes sodium channels, ankyrinG and βIV-spectrin AIS density, and AIS length, in cultured neurons and brain slices, accompanied by decreased neuronal excitability. We show that genetic downregulation of the mDia1 formin by interference RNAs also decreases AIS protein density and shortens AIS length. The ankyrinG decrease and AIS shortening observed in pharmacologically inhibited neurons and neuron-expressing mDia1 shRNAs were impaired by HDAC6 downregulation or EB1-GFP expression, known to increase microtubule acetylation or stability. However, actin stabilization only partially prevented AIS shortening without affecting AIS protein density loss. These results suggest that mDia1 maintain AIS composition and length contributing to the stability of AIS microtubules.
Collapse
Affiliation(s)
- Wei Zhang
- Instituto Cajal, CSIC, 28002, Madrid, Spain.,College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | | | | | | | | | | | - Michaël Russier
- UNIS, INSERM, UMR 1072, Aix-Marseille Université, 13015, Marseille, France
| | - Dominique Debanne
- UNIS, INSERM, UMR 1072, Aix-Marseille Université, 13015, Marseille, France
| | - Juan José Garrido
- Instituto Cajal, CSIC, 28002, Madrid, Spain. .,Alzheimer's Disease and Other Degenerative Dementias, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| |
Collapse
|
22
|
Plasmalogens regulate the AKT-ULK1 signaling pathway to control the position of the axon initial segment. Prog Neurobiol 2021; 205:102123. [PMID: 34302896 DOI: 10.1016/j.pneurobio.2021.102123] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/11/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023]
Abstract
The axon initial segment (AIS) is a specialized region in neurons that encompasses two essential functions, the generation of action potentials and the regulation of the axodendritic polarity. The mechanism controlling the position of the axon initial segment to allow plasticity and regulation of neuron excitability is unclear. Here we demonstrate that plasmalogens, the most abundant ether-phospholipid, are essential for the homeostatic positioning of the AIS. Plasmalogen deficiency is a hallmark of Rhizomelic Chondrodysplasia Punctata (RCDP) and Zellweger spectrum disorders, but Alzheimer's and Parkinson's disease, are also characterized by plasmalogen defects. Neurons lacking plasmalogens displaced the AIS to more distal positions and were characterized by reduced excitability. Treatment with a short-chain alkyl glycerol was able to rescue AIS positioning. Plasmalogen deficiency impaired AKT activation, and we show that inhibition of AKT phosphorylation at Ser473 and Thr308 is sufficient to induce a distal relocation of the AIS. Pathway analysis revealed that downstream of AKT, overtly active ULK1 mediates AIS repositioning. Rescuing the impaired AKT signaling pathway was able to normalize AIS position independently of the biochemical defect. These results unveil a previously unknown mechanism that couples the phospholipid composition of the neuronal membrane to the positional assembly of the AIS.
Collapse
|
23
|
Obashi K, Taraska JW, Okabe S. The role of molecular diffusion within dendritic spines in synaptic function. J Gen Physiol 2021; 153:e202012814. [PMID: 33720306 PMCID: PMC7967910 DOI: 10.1085/jgp.202012814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/16/2021] [Indexed: 12/21/2022] Open
Abstract
Spines are tiny nanoscale protrusions from dendrites of neurons. In the cortex and hippocampus, most of the excitatory postsynaptic sites reside in spines. The bulbous spine head is connected to the dendritic shaft by a thin membranous neck. Because the neck is narrow, spine heads are thought to function as biochemically independent signaling compartments. Thus, dynamic changes in the composition, distribution, mobility, conformations, and signaling properties of molecules contained within spines can account for much of the molecular basis of postsynaptic function and regulation. A major factor in controlling these changes is the diffusional properties of proteins within this small compartment. Advances in measurement techniques using fluorescence microscopy now make it possible to measure molecular diffusion within single dendritic spines directly. Here, we review the regulatory mechanisms of diffusion in spines by local intra-spine architecture and discuss their implications for neuronal signaling and synaptic plasticity.
Collapse
Affiliation(s)
- Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Justin W. Taraska
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
24
|
Prokop A. Cytoskeletal organization of axons in vertebrates and invertebrates. J Cell Biol 2021; 219:151734. [PMID: 32369543 PMCID: PMC7337489 DOI: 10.1083/jcb.201912081] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
The maintenance of axons for the lifetime of an organism requires an axonal cytoskeleton that is robust but also flexible to adapt to mechanical challenges and to support plastic changes of axon morphology. Furthermore, cytoskeletal organization has to adapt to axons of dramatically different dimensions, and to their compartment-specific requirements in the axon initial segment, in the axon shaft, at synapses or in growth cones. To understand how the cytoskeleton caters to these different demands, this review summarizes five decades of electron microscopic studies. It focuses on the organization of microtubules and neurofilaments in axon shafts in both vertebrate and invertebrate neurons, as well as the axon initial segments of vertebrate motor- and interneurons. Findings from these ultrastructural studies are being interpreted here on the basis of our contemporary molecular understanding. They strongly suggest that axon architecture in animals as diverse as arthropods and vertebrates is dependent on loosely cross-linked bundles of microtubules running all along axons, with only minor roles played by neurofilaments.
Collapse
Affiliation(s)
- Andreas Prokop
- School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
| |
Collapse
|
25
|
Glanc M, Van Gelderen K, Hoermayer L, Tan S, Naramoto S, Zhang X, Domjan D, Včelařová L, Hauschild R, Johnson A, de Koning E, van Dop M, Rademacher E, Janson S, Wei X, Molnár G, Fendrych M, De Rybel B, Offringa R, Friml J. AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells. Curr Biol 2021; 31:1918-1930.e5. [PMID: 33705718 PMCID: PMC8112251 DOI: 10.1016/j.cub.2021.02.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/22/2021] [Accepted: 02/12/2021] [Indexed: 12/22/2022]
Abstract
Polar subcellular localization of the PIN exporters of the phytohormone auxin is a key determinant of directional, intercellular auxin transport and thus a central topic of both plant cell and developmental biology. Arabidopsis mutants lacking PID, a kinase that phosphorylates PINs, or the MAB4/MEL proteins of unknown molecular function display PIN polarity defects and phenocopy pin mutants, but mechanistic insights into how these factors convey PIN polarity are missing. Here, by combining protein biochemistry with quantitative live-cell imaging, we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane. MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity through limiting lateral diffusion-based escape of PINs from the polar domain. The PIN-MAB4/MEL-PID protein complex has self-reinforcing properties thanks to positive feedback between AGC kinase-mediated PIN phosphorylation and MAB4/MEL recruitment. We thus uncover the molecular mechanism by which AGC kinases and MAB4/MEL proteins regulate PIN localization and plant development. MAB4/MEL proteins are recruited to the plasma membrane by PINs PINs, MAB4/MELs, and AGC kinases directly interact in a multiprotein complex PIN phosphorylation and MAB4/MEL recruitment form a positive feedback loop MAB4/MELs and AGC kinases maintain PIN polarity by limiting PIN lateral diffusion
Collapse
Affiliation(s)
- Matouš Glanc
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czechia; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Kasper Van Gelderen
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands; Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Lukas Hoermayer
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Shutang Tan
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Satoshi Naramoto
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Xixi Zhang
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - David Domjan
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Ludmila Včelařová
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Robert Hauschild
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Alexander Johnson
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Edward de Koning
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands
| | - Maritza van Dop
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands
| | - Eike Rademacher
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands
| | - Stef Janson
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands
| | - Xiaoyu Wei
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands
| | - Gergely Molnár
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, (BOKU), 1190 Vienna, Austria
| | - Matyáš Fendrych
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czechia
| | - Bert De Rybel
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Remko Offringa
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands.
| | - Jiří Friml
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.
| |
Collapse
|
26
|
Solé L, Tamkun MM. Trafficking mechanisms underlying Na v channel subcellular localization in neurons. Channels (Austin) 2020; 14:1-17. [PMID: 31841065 PMCID: PMC7039628 DOI: 10.1080/19336950.2019.1700082] [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: 10/25/2019] [Accepted: 11/13/2019] [Indexed: 01/06/2023] Open
Abstract
Voltage gated sodium channels (Nav) play a crucial role in action potential initiation and propagation. Although the discovery of Nav channels dates back more than 65 years, and great advances in understanding their localization, biophysical properties, and links to disease have been made, there are still many questions to be answered regarding the cellular and molecular mechanisms involved in Nav channel trafficking, localization and regulation. This review summarizes the different trafficking mechanisms underlying the polarized Nav channel localization in neurons, with an emphasis on the axon initial segment (AIS), as well as discussing the latest advances regarding how neurons regulate their excitability by modifying AIS length and location. The importance of Nav channel localization is emphasized by the relationship between mutations, impaired trafficking and disease. While this review focuses on Nav1.6, other Nav isoforms are also discussed.
Collapse
Affiliation(s)
- Laura Solé
- Molecular, Cellular and Integrative Neurosciences Graduate Program, Colorado State University, Fort Collins, CO, USA
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Michael M. Tamkun
- Molecular, Cellular and Integrative Neurosciences Graduate Program, Colorado State University, Fort Collins, CO, USA
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| |
Collapse
|
27
|
Lenton ICD, Scott EK, Rubinsztein-Dunlop H, Favre-Bulle IA. Optical Tweezers Exploring Neuroscience. Front Bioeng Biotechnol 2020; 8:602797. [PMID: 33330435 PMCID: PMC7732537 DOI: 10.3389/fbioe.2020.602797] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/04/2020] [Indexed: 12/30/2022] Open
Abstract
Over the past decade, optical tweezers (OT) have been increasingly used in neuroscience for studies of molecules and neuronal dynamics, as well as for the study of model organisms as a whole. Compared to other areas of biology, it has taken much longer for OT to become an established tool in neuroscience. This is, in part, due to the complexity of the brain and the inherent difficulties in trapping individual molecules or manipulating cells located deep within biological tissue. Recent advances in OT, as well as parallel developments in imaging and adaptive optics, have significantly extended the capabilities of OT. In this review, we describe how OT became an established tool in neuroscience and we elaborate on possible future directions for the field. Rather than covering all applications of OT to neurons or related proteins and molecules, we focus our discussions on studies that provide crucial information to neuroscience, such as neuron dynamics, growth, and communication, as these studies have revealed meaningful information and provide direction for the field into the future.
Collapse
Affiliation(s)
- Isaac C. D. Lenton
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, Australia
| | - Ethan K. Scott
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | | | - Itia A. Favre-Bulle
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| |
Collapse
|
28
|
Stone MC, Kothe GO, Rolls MM, Jegla T. Cytoskeletal and synaptic polarity of LWamide-like+ ganglion neurons in the sea anemone Nematostella vectensis. J Exp Biol 2020; 223:jeb233197. [PMID: 32968001 PMCID: PMC7673360 DOI: 10.1242/jeb.233197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 09/14/2020] [Indexed: 12/22/2022]
Abstract
The centralized nervous systems of bilaterian animals rely on directional signaling facilitated by polarized neurons with specialized axons and dendrites. It is not known whether axo-dendritic polarity is exclusive to bilaterians or was already present in early metazoans. We therefore examined neurite polarity in the starlet sea anemone Nematostella vectensis (Cnidaria). Cnidarians form a sister clade to bilaterians and share many neuronal building blocks characteristic of bilaterians, including channels, receptors and synaptic proteins, but their nervous systems comprise a comparatively simple net distributed throughout the body. We developed a tool kit of fluorescent polarity markers for live imaging analysis of polarity in an identified neuron type, large ganglion cells of the body column nerve net that express the LWamide-like neuropeptide. Microtubule polarity differs in bilaterian axons and dendrites, and this in part underlies polarized distribution of cargo to the two types of processes. However, in LWamide-like+ neurons, all neurites had axon-like microtubule polarity suggesting that they may have similar contents. Indeed, presynaptic and postsynaptic markers trafficked to all neurites and accumulated at varicosities where neurites from different neurons often crossed, suggesting the presence of bidirectional synaptic contacts. Furthermore, we could not identify a diffusion barrier in the plasma membrane of any of the neurites like the axon initial segment barrier that separates the axonal and somatodendritic compartments in bilaterian neurons. We conclude that at least one type of neuron in Nematostella vectensis lacks the axo-dendritic polarity characteristic of bilaterian neurons.
Collapse
Affiliation(s)
- Michelle C Stone
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Gregory O Kothe
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Melissa M Rolls
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Timothy Jegla
- Department of Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| |
Collapse
|
29
|
Ravenscroft TA, Janssens J, Lee PT, Tepe B, Marcogliese PC, Makhzami S, Holmes TC, Aerts S, Bellen HJ. Drosophila Voltage-Gated Sodium Channels Are Only Expressed in Active Neurons and Are Localized to Distal Axonal Initial Segment-like Domains. J Neurosci 2020; 40:7999-8024. [PMID: 32928889 PMCID: PMC7574647 DOI: 10.1523/jneurosci.0142-20.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 07/15/2020] [Accepted: 08/04/2020] [Indexed: 12/28/2022] Open
Abstract
In multipolar vertebrate neurons, action potentials (APs) initiate close to the soma, at the axonal initial segment. Invertebrate neurons are typically unipolar with dendrites integrating directly into the axon. Where APs are initiated in the axons of invertebrate neurons is unclear. Voltage-gated sodium (NaV) channels are a functional hallmark of the axonal initial segment in vertebrates. We used an intronic Minos-Mediated Integration Cassette to determine the endogenous gene expression and subcellular localization of the sole NaV channel in both male and female Drosophila, para Despite being the only NaV channel in the fly, we show that only 23 ± 1% of neurons in the embryonic and larval CNS express para, while in the adult CNS para is broadly expressed. We generated a single-cell transcriptomic atlas of the whole third instar larval brain to identify para expressing neurons and show that it positively correlates with markers of differentiated, actively firing neurons. Therefore, only 23 ± 1% of larval neurons may be capable of firing NaV-dependent APs. We then show that Para is enriched in an axonal segment, distal to the site of dendritic integration into the axon, which we named the distal axonal segment (DAS). The DAS is present in multiple neuron classes in both the third instar larval and adult CNS. Whole cell patch clamp electrophysiological recordings of adult CNS fly neurons are consistent with the interpretation that Nav-dependent APs originate in the DAS. Identification of the distal NaV localization in fly neurons will enable more accurate interpretation of electrophysiological recordings in invertebrates.SIGNIFICANCE STATEMENT The site of action potential (AP) initiation in invertebrates is unknown. We tagged the sole voltage-gated sodium (NaV) channel in the fly, para, and identified that Para is enriched at a distal axonal segment. The distal axonal segment is located distal to where dendrites impinge on axons and is the likely site of AP initiation. Understanding where APs are initiated improves our ability to model neuronal activity and our interpretation of electrophysiological data. Additionally, para is only expressed in 23 ± 1% of third instar larval neurons but is broadly expressed in adults. Single-cell RNA sequencing of the third instar larval brain shows that para expression correlates with the expression of active, differentiated neuronal markers. Therefore, only 23 ± 1% of third instar larval neurons may be able to actively fire NaV-dependent APs.
Collapse
Affiliation(s)
- Thomas A Ravenscroft
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Jasper Janssens
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Burak Tepe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Samira Makhzami
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California at Irvine, Irvine, California 92697
| | - Stein Aerts
- VIB Center for Brain & Disease Research, KU Leuven, Leuven 3000, Belgium
- Department of Human Genetics, KU Leuven, Leuven 3000, Belgium
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030
| |
Collapse
|
30
|
Ghosh A, Malavasi EL, Sherman DL, Brophy PJ. Neurofascin and Kv7.3 are delivered to somatic and axon terminal surface membranes en route to the axon initial segment. eLife 2020; 9:60619. [PMID: 32903174 PMCID: PMC7511229 DOI: 10.7554/elife.60619] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/08/2020] [Indexed: 12/15/2022] Open
Abstract
Ion channel complexes promote action potential initiation at the mammalian axon initial segment (AIS), and modulation of AIS size by recruitment or loss of proteins can influence neuron excitability. Although endocytosis contributes to AIS turnover, how membrane proteins traffic to this proximal axonal domain is incompletely understood. Neurofascin186 (Nfasc186) has an essential role in stabilising the AIS complex to the proximal axon, and the AIS channel protein Kv7.3 regulates neuron excitability. Therefore, we have studied how these proteins reach the AIS. Vesicles transport Nfasc186 to the soma and axon terminal where they fuse with the neuronal plasma membrane. Nfasc186 is highly mobile after insertion in the axonal membrane and diffuses bidirectionally until immobilised at the AIS through its interaction with AnkyrinG. Kv7.3 is similarly recruited to the AIS. This study reveals how key proteins are delivered to the AIS and thereby how they may contribute to its functional plasticity.
Collapse
Affiliation(s)
- Aniket Ghosh
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Elise Lv Malavasi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Diane L Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
31
|
Ichinose S, Ogawa T, Jiang X, Hirokawa N. The Spatiotemporal Construction of the Axon Initial Segment via KIF3/KAP3/TRIM46 Transport under MARK2 Signaling. Cell Rep 2020; 28:2413-2426.e7. [PMID: 31461655 DOI: 10.1016/j.celrep.2019.07.093] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 06/18/2019] [Accepted: 07/23/2019] [Indexed: 01/23/2023] Open
Abstract
The axon initial segment (AIS) is a compartment that serves as a molecular barrier to achieve axon-dendrite differentiation. Distribution of specific proteins during early neuronal development has been proposed to be critical for AIS construction. However, it remains unknown how these proteins are specifically targeted to the proximal axon within this limited time period. Here, we reveal spatiotemporal regulation driven by the microtubule (MT)-based motor KIF3A/B/KAP3 that transports TRIM46, influenced by a specific MARK2 phosphorylation cascade. In the proximal part of the future axon under low MARK2 activity, the KIF3/KAP3 motor recognizes TRIM46 as cargo and transports it to the future AIS. In contrast, in the somatodendritic area under high MARK2 activity, KAP3 phosphorylated at serine 60 by MARK2 cannot bind with TRIM46 and be transported. This spatiotemporal regulation between KIF3/KAP3 and TRIM46 under specific MARK2 activity underlies the specific transport needed for axonal differentiation.
Collapse
Affiliation(s)
- Sotaro Ichinose
- Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tadayuki Ogawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Xuguang Jiang
- Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Nobutaka Hirokawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Center of Excellence in Genome Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.
| |
Collapse
|
32
|
Gallo NB, Paul A, Van Aelst L. Shedding Light on Chandelier Cell Development, Connectivity, and Contribution to Neural Disorders. Trends Neurosci 2020; 43:565-580. [PMID: 32564887 PMCID: PMC7392791 DOI: 10.1016/j.tins.2020.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/06/2020] [Accepted: 05/07/2020] [Indexed: 02/04/2023]
Abstract
Chandelier cells (ChCs) are a unique type of GABAergic interneuron that selectively innervate the axon initial segment (AIS) of excitatory pyramidal neurons; the subcellular domain where action potentials are initiated. The proper genesis and maturation of ChCs is critical for regulating neural ensemble firing in the neocortex throughout development and adulthood. Recently, genetic and molecular studies have shed new light on the complex innerworkings of ChCs in health and disease. This review presents an overview of recent studies on the developmental origins, migratory properties, and morphology of ChCs. In addition, attention is given to newly identified molecules regulating ChC morphogenesis and connectivity as well as recent work linking ChC dysfunction to neural disorders, including schizophrenia, epilepsy, and autism spectrum disorder (ASD).
Collapse
Affiliation(s)
- Nicholas B Gallo
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Anirban Paul
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Linda Van Aelst
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA.
| |
Collapse
|
33
|
Nicholson L, Gervasi N, Falières T, Leroy A, Miremont D, Zala D, Hanus C. Whole-Cell Photobleaching Reveals Time-Dependent Compartmentalization of Soluble Proteins by the Axon Initial Segment. Front Cell Neurosci 2020; 14:180. [PMID: 32754013 PMCID: PMC7366827 DOI: 10.3389/fncel.2020.00180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/27/2020] [Indexed: 01/12/2023] Open
Abstract
By limiting protein exchange between the soma and the axon, the axon initial segment (AIS) enables the segregation of specific proteins and hence the differentiation of the somatodendritic compartment and the axonal compartment. Electron microscopy and super-resolution fluorescence imaging have provided important insights in the ultrastructure of the AIS. Yet, the full extent of its filtering properties is not fully delineated. In particular, it is unclear whether and how the AIS opposes the free exchange of soluble proteins. Here we describe a robust framework to combine whole-cell photobleaching and retrospective high-resolution imaging in developing neurons. With this assay, we found that cytoplasmic soluble proteins that are not excluded from the axon upon expression over tens of hours exhibit a strong mobility reduction at the AIS – i.e., are indeed compartmentalized – when monitored over tens of minutes. This form of compartmentalization is developmentally regulated, requires intact F-actin and may be correlated with the composition and ultrastructure of the submembranous spectrin cytoskeleton. Using computational modeling, we provide evidence that both neuronal morphology and the AIS regulate this compartmentalization but act on distinct time scales, with the AIS having a more pronounced effect on fast exchanges. Our results thus suggest that the rate of protein accumulation in the soma may impact to what extent and over which timescales freely moving molecules can be segregated from the axon. This in turn has important implications for our understanding of compartment-specific signaling in neurons.
Collapse
Affiliation(s)
- LaShae Nicholson
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
| | - Nicolas Gervasi
- Center for Interdisciplinary Research in Biology, College de France, Inserm U1050, CNRS UMR 7241, Labex Memolife, Paris, France
| | - Thibault Falières
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Adrien Leroy
- Center for Interdisciplinary Research in Biology, College de France, Inserm U1050, CNRS UMR 7241, Labex Memolife, Paris, France
| | - Dorian Miremont
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Diana Zala
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Cyril Hanus
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| |
Collapse
|
34
|
Abouelezz A, Stefen H, Segerstråle M, Micinski D, Minkeviciene R, Lahti L, Hardeman EC, Gunning PW, Hoogenraad CC, Taira T, Fath T, Hotulainen P. Tropomyosin Tpm3.1 Is Required to Maintain the Structure and Function of the Axon Initial Segment. iScience 2020; 23:101053. [PMID: 32344377 PMCID: PMC7186529 DOI: 10.1016/j.isci.2020.101053] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 03/05/2020] [Accepted: 04/06/2020] [Indexed: 12/26/2022] Open
Abstract
The axon initial segment (AIS) is the site of action potential initiation and serves as a cargo transport filter and diffusion barrier that helps maintain neuronal polarity. The AIS actin cytoskeleton comprises actin patches and periodic sub-membranous actin rings. We demonstrate that tropomyosin isoform Tpm3.1 co-localizes with actin patches and that the inhibition of Tpm3.1 led to a reduction in the density of actin patches. Furthermore, Tpm3.1 showed a periodic distribution similar to sub-membranous actin rings but Tpm3.1 was only partially congruent with sub-membranous actin rings. Nevertheless, the inhibition of Tpm3.1 affected the uniformity of the periodicity of actin rings. Furthermore, Tpm3.1 inhibition led to reduced accumulation of AIS structural and functional proteins, disruption in sorting somatodendritic and axonal proteins, and a reduction in firing frequency. These results show that Tpm3.1 is necessary for the structural and functional maintenance of the AIS. Tropomyosin isoform Tpm3.1 co-localizes with the actin cytoskeleton in the AIS Tpm3.1 inhibition led to a less organized AIS actin cytoskeleton Perturbation of Tpm3.1 function reduced the accumulation of AIS scaffolding proteins Tpm3.1 inhibition compromised cargo sorting and rapidly reduced firing frequency
Collapse
Affiliation(s)
- Amr Abouelezz
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, 00290 Helsinki, Finland; HiLIFE - Neuroscience Center, University of Helsinki, Haartmaninkatu 8, 00290 Helsinki, Finland
| | - Holly Stefen
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Mikael Segerstråle
- Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1, 00790 Helsinki, Finland
| | - David Micinski
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Rimante Minkeviciene
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Lauri Lahti
- Department of Computer Science, Aalto University School of Science, Espoo, Finland
| | - Edna C Hardeman
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Peter W Gunning
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Casper C Hoogenraad
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584CH Utrecht, the Netherlands
| | - Tomi Taira
- Faculty of Veterinary Medicine, University of Helsinki, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland
| | - Thomas Fath
- School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; Dementia Research Centre, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, 00290 Helsinki, Finland.
| |
Collapse
|
35
|
MAP7D2 Localizes to the Proximal Axon and Locally Promotes Kinesin-1-Mediated Cargo Transport into the Axon. Cell Rep 2020; 26:1988-1999.e6. [PMID: 30784582 PMCID: PMC6381606 DOI: 10.1016/j.celrep.2019.01.084] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 12/20/2018] [Accepted: 01/24/2019] [Indexed: 11/20/2022] Open
Abstract
The motor protein kinesin-1 plays an important role in polarized sorting of transport vesicles to the axon. However, the mechanism by which the axonal entry of kinesin-1-dependent cargo transport is regulated remains unclear. Microtubule-associated protein MAP7 (ensconsin in Drosophila) is an essential kinesin-1 cofactor and promotes kinesin-1 recruitment to microtubules. Here, we found that MAP7 family member MAP7D2 concentrates at the proximal axon, where it overlaps with the axon initial segment and interacts with kinesin-1. Depletion of MAP7D2 results in reduced axonal cargo entry and defects in axon development and neuronal migration. We propose a model in which MAP7D2 in the proximal axon locally promotes kinesin-1-mediated cargo entry into the axon.
Collapse
|
36
|
Goaillard JM, Moubarak E, Tapia M, Tell F. Diversity of Axonal and Dendritic Contributions to Neuronal Output. Front Cell Neurosci 2020; 13:570. [PMID: 32038171 PMCID: PMC6987044 DOI: 10.3389/fncel.2019.00570] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/09/2019] [Indexed: 11/13/2022] Open
Abstract
Our general understanding of neuronal function is that dendrites receive information that is transmitted to the axon, where action potentials (APs) are initiated and propagated to eventually trigger neurotransmitter release at synaptic terminals. Even though this canonical division of labor is true for a number of neuronal types in the mammalian brain (including neocortical and hippocampal pyramidal neurons or cerebellar Purkinje neurons), many neuronal types do not comply with this classical polarity scheme. In fact, dendrites can be the site of AP initiation and propagation, and even neurotransmitter release. In several interneuron types, all functions are carried out by dendrites as these neurons are devoid of a canonical axon. In this article, we present a few examples of "misbehaving" neurons (with a non-canonical polarity scheme) to highlight the diversity of solutions that are used by mammalian neurons to transmit information. Moreover, we discuss how the contribution of dendrites and axons to neuronal excitability may impose constraints on the morphology of these compartments in specific functional contexts.
Collapse
Affiliation(s)
- Jean-Marc Goaillard
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Estelle Moubarak
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Mónica Tapia
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Fabien Tell
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| |
Collapse
|
37
|
Hamdan H, Lim BC, Torii T, Joshi A, Konning M, Smith C, Palmer DJ, Ng P, Leterrier C, Oses-Prieto JA, Burlingame AL, Rasband MN. Mapping axon initial segment structure and function by multiplexed proximity biotinylation. Nat Commun 2020; 11:100. [PMID: 31900387 PMCID: PMC6941957 DOI: 10.1038/s41467-019-13658-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 11/15/2019] [Indexed: 12/19/2022] Open
Abstract
Axon initial segments (AISs) generate action potentials and regulate the polarized distribution of proteins, lipids, and organelles in neurons. While the mechanisms of AIS Na+ and K+ channel clustering are understood, the molecular mechanisms that stabilize the AIS and control neuronal polarity remain obscure. Here, we use proximity biotinylation and mass spectrometry to identify the AIS proteome. We target the biotin-ligase BirA* to the AIS by generating fusion proteins of BirA* with NF186, Ndel1, and Trim46; these chimeras map the molecular organization of AIS intracellular membrane, cytosolic, and microtubule compartments. Our experiments reveal a diverse set of biotinylated proteins not previously reported at the AIS. We show many are located at the AIS, interact with known AIS proteins, and their loss disrupts AIS structure and function. Our results provide conceptual insights and a resource for AIS molecular organization, the mechanisms of AIS stability, and polarized trafficking in neurons.
Collapse
Affiliation(s)
- Hamdan Hamdan
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.,Department of Physiology, College of Medicine, Alfaisal University, Riyadh, 11533, Saudi Arabia
| | - Brian C Lim
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Tomohiro Torii
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Abhijeet Joshi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Matthias Konning
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Cameron Smith
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Donna J Palmer
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Philip Ng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Juan A Oses-Prieto
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
| | - Matthew N Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
| |
Collapse
|
38
|
Mechanistic insights into the interactions of dynein regulator Ndel1 with neuronal ankyrins and implications in polarity maintenance. Proc Natl Acad Sci U S A 2019; 117:1207-1215. [PMID: 31889000 DOI: 10.1073/pnas.1916987117] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ankyrin-G (AnkG), a highly enriched scaffold protein in the axon initial segment (AIS) of neurons, functions to maintain axonal polarity and the integrity of the AIS. At the AIS, AnkG regulates selective intracellular cargo trafficking between soma and axons via interaction with the dynein regulator protein Ndel1, but the molecular mechanism underlying this binding remains elusive. Here we report that Ndel1's C-terminal coiled-coil region (CT-CC) binds to giant neuron-specific insertion regions present in both AnkG and AnkB with 2:1 stoichiometry. The high-resolution crystal structure of AnkB in complex with Ndel1 CT-CC revealed the detailed molecular basis governing the AnkB/Ndel1 complex formation. Mechanistically, AnkB binds with Ndel1 by forming a stable 5-helix bundle dominated by hydrophobic interactions spread across 6 distinct interaction layers. Moreover, we found that AnkG is essential for Ndel1 accumulation at the AIS. Finally, we found that cargo sorting at the AIS can be disrupted by blocking the AnkG/Ndel1 complex formation using a peptide designed based on our structural data. Collectively, the atomic structure of the AnkB/Ndel1 complex together with studies of cargo sorting through the AIS establish the mechanistic basis for AnkG/Ndel1 complex formation and for the maintenance of axonal polarity. Our study will also be valuable for future studies of the interaction between AnkB and Ndel1 perhaps at distal axonal cargo transport.
Collapse
|
39
|
Kovtun O, Tomlinson ID, Ferguson RS, Rosenthal SJ. Quantum dots reveal heterogeneous membrane diffusivity and dynamic surface density polarization of dopamine transporter. PLoS One 2019; 14:e0225339. [PMID: 31751387 PMCID: PMC6872175 DOI: 10.1371/journal.pone.0225339] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022] Open
Abstract
The presynaptic dopamine transporter mediates rapid reuptake of synaptic dopamine. Although cell surface DAT trafficking recently emerged as an important component of DAT regulation, it has not been systematically investigated. Here, we apply our single quantum dot (Qdot) tracking approach to monitor DAT plasma membrane dynamics in several heterologous expression cell hosts with nanometer localization accuracy. We demonstrate that Qdot-tagged DAT proteins exhibited highly heterogeneous membrane diffusivity dependent on the local membrane topography. We also show that Qdot-tagged DATs were localized away from the flat membrane regions and were dynamically retained in the membrane protrusions and cell edges for the duration of imaging. Single quantum dot tracking of wildtype DAT and its conformation-defective coding variants (R60A and W63A) revealed a significantly accelerated rate of dysfunctional DAT membrane diffusion. We believe our results warrant an in-depth investigation as to whether compromised membrane dynamics is a common feature of brain disorder-derived DAT mutants.
Collapse
Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Riley S. Ferguson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
| |
Collapse
|
40
|
Khalaf B, Roncador A, Pischedda F, Casini A, Thomas S, Piccoli G, Kiebler M, Macchi P. Ankyrin-G induces nucleoporin Nup358 to associate with the axon initial segment of neurons. J Cell Sci 2019; 132:jcs.222802. [PMID: 31427429 DOI: 10.1242/jcs.222802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/12/2019] [Indexed: 12/11/2022] Open
Abstract
Nup358 (also known as RanBP2) is a member of the large nucleoporin family that constitutes the nuclear pore complex. Depending on the cell type and the physiological state, Nup358 interacts with specific partner proteins and influences distinct mechanisms independent of its role in nucleocytoplasmic transport. Here, we provide evidence that Nup358 associates selectively with the axon initial segment (AIS) of mature neurons, mediated by the AIS scaffold protein ankyrin-G (AnkG, also known as Ank3). The N-terminus of Nup358 is demonstrated to be sufficient for its localization at the AIS. Further, we show that Nup358 is expressed as two isoforms, one full-length and another shorter form of Nup358. These isoforms differ in their subcellular distribution in neurons and expression level during neuronal development. Overall, the present study highlights an unprecedented localization of Nup358 within the AIS and suggests its involvement in neuronal function.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Bouchra Khalaf
- Laboratory of Molecular and Cellular Neurobiology, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| | - Alessandro Roncador
- Laboratory of Molecular and Cellular Neurobiology, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| | - Francesca Pischedda
- Dulbecco Telethon Laboratory of Biology of Synapses, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| | - Antonio Casini
- Laboratory of Molecular Virology, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| | - Sabine Thomas
- Department for Cell Biology, Biomedical Center, Medical Faculty, Ludwig-Maximilian University of Munich, Großhaderner Straße 9, 82152 Planegg-Martinsried, Germany
| | - Giovanni Piccoli
- Dulbecco Telethon Laboratory of Biology of Synapses, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| | - Michael Kiebler
- Department for Cell Biology, Biomedical Center, Medical Faculty, Ludwig-Maximilian University of Munich, Großhaderner Straße 9, 82152 Planegg-Martinsried, Germany
| | - Paolo Macchi
- Laboratory of Molecular and Cellular Neurobiology, Department of Cellular, Computational and Integrative Biology-CIBIO, University of Trento, 38123 Trento, Italy
| |
Collapse
|
41
|
Ittner A, Ittner LM. Dendritic Tau in Alzheimer's Disease. Neuron 2019; 99:13-27. [PMID: 30001506 DOI: 10.1016/j.neuron.2018.06.003] [Citation(s) in RCA: 159] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/07/2018] [Accepted: 06/01/2018] [Indexed: 01/08/2023]
Abstract
The microtubule-associated protein tau and amyloid-β (Aβ) are key players in Alzheimer's disease (AD). Aβ and tau are linked in a molecular pathway at the post-synapse with tau-dependent synaptic dysfunction being a major pathomechanism in AD. Recent work on site-specific modification of dendritic and more specifically post-synaptic tau has revealed new endogenous functions of tau that limits synaptic Aβ toxicity. Thus, molecular studies opened a new perspective on tau, placing it at the center of neurotoxic and neuroprotective signaling at the post-synapse. Here, we review recent advances on tau in the dendritic compartments, with implications for understanding and treatment of AD and related neurological conditions.
Collapse
Affiliation(s)
- Arne Ittner
- Dementia Research Unit, School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Lars M Ittner
- Dementia Research Unit, School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia; Neuroscience Research Australia, Sydney, New South Wales 2031, Australia; Dementia Research Centre, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
| |
Collapse
|
42
|
Zhang Y, Tzingounis AV, Lykotrafitis G. Modeling of the axon plasma membrane structure and its effects on protein diffusion. PLoS Comput Biol 2019; 15:e1007003. [PMID: 31048841 PMCID: PMC6497228 DOI: 10.1371/journal.pcbi.1007003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 04/03/2019] [Indexed: 11/30/2022] Open
Abstract
The axon plasma membrane consists of the membrane skeleton, which comprises ring-like actin filaments connected to each other by spectrin tetramers, and the lipid bilayer, which is tethered to the skeleton via, at least, ankyrin. Currently it is unknown whether this unique axon plasma membrane skeleton (APMS) sets the diffusion rules of lipids and proteins in the axon. To answer this question, we developed a coarse-grain molecular dynamics model for the axon that includes the APMS, the phospholipid bilayer, transmembrane proteins (TMPs), and integral monotopic proteins (IMPs) in both the inner and outer lipid layers. We first showed that actin rings limit the longitudinal diffusion of TMPs and the IMPs of the inner leaflet but not of the IMPs of the outer leaflet. To reconcile the experimental observations, which show restricted diffusion of IMPs of the outer leaflet, with our simulations, we conjectured the existence of actin-anchored proteins that form a fence which restricts the longitudinal diffusion of IMPs of the outer leaflet. We also showed that spectrin filaments could modify transverse diffusion of TMPs and IMPs of the inner leaflet, depending on the strength of the association between lipids and spectrin. For instance, in areas where spectrin binds to the lipid bilayer, spectrin filaments would restrict diffusion of proteins within the skeleton corrals. In contrast, in areas where spectrin and lipids are not associated, spectrin modifies the diffusion of TMPs and IMPs of the inner leaflet from normal to confined-hop diffusion. Overall, we showed that diffusion of axon plasma membrane proteins is deeply anisotropic, as longitudinal diffusion is of different type than transverse diffusion. Finally, we investigated how accumulation of TMPs affects diffusion of TMPs and IMPs of both the inner and outer leaflets by changing the density of TMPs. We showed that the APMS structure acts as a fence that restricts the diffusion of TMPs and IMPs of the inner leaflet within the membrane skeleton corrals. Our findings provide insight into how the axon skeleton acts as diffusion barrier and maintains neuronal polarity. The axon plasma membrane skeleton consists of repeated periodic actin ring-like structures along its length connected via spectrin tetramers and anchored to the lipid bilayer at least via ankyrin. However, it is currently unclear whether this structure controls diffusion of lipids and proteins in the axon. Here, we developed a coarse-grain molecular dynamics computational model for the axon plasma membrane that comprises minimal representations for the APMS and the lipid bilayer. In a departure from current models, we found that actin rings limit diffusion of proteins only in the inner membrane leaflet. Then, we showed that actin anchored proteins likely act as “fences” confining diffusion of proteins in the outer leaflet. Our simulations, unexpectedly, also revealed that spectrin filaments could impede transverse diffusion in the inner leaflet of the axon and in some conditions modify diffusion from normal to abnormal. We predicted that diffusion of axon plasma membrane proteins is anisotropic as longitudinal diffusion is of different type than transverse (azimuthal) diffusion. We conclude that the periodic structure of the axon plays a critical role in controlling diffusion of proteins and lipids in the axon plasma membrane.
Collapse
Affiliation(s)
- Yihao Zhang
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, United States of America
| | - Anastasios V. Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States of America
| | - George Lykotrafitis
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, United States of America
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States of America
- * E-mail:
| |
Collapse
|
43
|
Tai Y, Gallo NB, Wang M, Yu JR, Van Aelst L. Axo-axonic Innervation of Neocortical Pyramidal Neurons by GABAergic Chandelier Cells Requires AnkyrinG-Associated L1CAM. Neuron 2019; 102:358-372.e9. [PMID: 30846310 DOI: 10.1016/j.neuron.2019.02.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 12/20/2018] [Accepted: 02/04/2019] [Indexed: 11/17/2022]
Abstract
Among the diverse interneuron subtypes in the neocortex, chandelier cells (ChCs) are the only population that selectively innervate pyramidal neurons (PyNs) at their axon initial segment (AIS), the site of action potential initiation, allowing them to exert powerful control over PyN output. Yet, mechanisms underlying their subcellular innervation of PyN AISs are unknown. To identify molecular determinants of ChC/PyN AIS innervation, we performed an in vivo RNAi screen of PyN-expressed axonal cell adhesion molecules (CAMs) and select Ephs/ephrins. Strikingly, we found the L1 family member L1CAM to be the only molecule required for ChC/PyN AIS innervation. Further, we show that L1CAM is required during both the establishment and maintenance of innervation, and that selective innervation of PyN AISs by ChCs requires AIS anchoring of L1CAM by the cytoskeletal ankyrin-G/βIV-spectrin complex. Thus, our findings identify PyN-expressed L1CAM as a critical CAM required for innervation of neocortical PyN AISs by ChCs. VIDEO ABSTRACT.
Collapse
Affiliation(s)
- Yilin Tai
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Nicholas B Gallo
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794, USA
| | - Minghui Wang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Jia-Ray Yu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Linda Van Aelst
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
| |
Collapse
|
44
|
Spurrier J, Shukla AK, Buckley T, Smith-Trunova S, Kuzina I, Gu Q, Giniger E. Expression of a Fragment of Ankyrin 2 Disrupts the Structure of the Axon Initial Segment and Causes Axonal Degeneration in Drosophila. Mol Neurobiol 2019; 56:5689-5700. [PMID: 30666562 DOI: 10.1007/s12035-019-1477-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/10/2019] [Indexed: 11/26/2022]
Abstract
Neurodegenerative stimuli are often associated with perturbation of the axon initial segment (AIS), but it remains unclear whether AIS disruption is causative for neurodegeneration or is a downstream step in disease progression. Here, we demonstrate that either of two separate, genetically parallel pathways that disrupt the AIS induce axonal degeneration and loss of neurons in the central brain of Drosophila. Expression of a portion of the C-terminal tail of the Ank2-L isoform of Ankyrin severely shortens the AIS in Drosophila mushroom body (MB) neurons, and this shortening occurs through a mechanism that is genetically separate from the previously described Cdk5α-dependent pathway of AIS regulation. Further, either manipulation triggers morphological degeneration of MB axons and is accompanied by neuron loss. Taken together, our results are consistent with the hypothesis that disruption of the AIS is causally related to degeneration of fly central brain neurons, and we suggest that similar mechanisms may contribute to neurodegeneration in mammals.
Collapse
Affiliation(s)
- Joshua Spurrier
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- Cellular Neuroscience, Neurodegeneration and Repair Program, Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Arvind K Shukla
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Tyler Buckley
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- The Scripps Research Institute, San Diego, CA, USA
| | - Svetlana Smith-Trunova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Irina Kuzina
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Qun Gu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA.
| |
Collapse
|
45
|
Donato A, Kagias K, Zhang Y, Hilliard MA. Neuronal sub-compartmentalization: a strategy to optimize neuronal function. Biol Rev Camb Philos Soc 2019; 94:1023-1037. [PMID: 30609235 PMCID: PMC6617802 DOI: 10.1111/brv.12487] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 11/21/2018] [Accepted: 11/23/2018] [Indexed: 12/14/2022]
Abstract
Neurons are highly polarized cells that consist of three main structural and functional domains: a cell body or soma, an axon, and dendrites. These domains contain smaller compartments with essential roles for proper neuronal function, such as the axonal presynaptic boutons and the dendritic postsynaptic spines. The structure and function of these compartments have now been characterized in great detail. Intriguingly, however, in the last decade additional levels of compartmentalization within the axon and the dendrites have been identified, revealing that these structures are much more complex than previously thought. Herein we examine several types of structural and functional sub-compartmentalization found in neurons of both vertebrates and invertebrates. For example, in mammalian neurons the axonal initial segment functions as a sub-compartment to initiate the action potential, to select molecules passing into the axon, and to maintain neuronal polarization. Moreover, work in Drosophila melanogaster has shown that two distinct axonal guidance receptors are precisely clustered in adjacent segments of the commissural axons both in vivo and in vitro, suggesting a cell-intrinsic mechanism underlying the compartmentalized receptor localization. In Caenorhabditis elegans, a subset of interneurons exhibits calcium dynamics that are localized to specific sections of the axon and control the gait of navigation, demonstrating a regulatory role of compartmentalized neuronal activity in behaviour. These findings have led to a number of new questions, which are important for our understanding of neuronal development and function. How are these sub-compartments established and maintained? What molecular machinery and cellular events are involved? What is their functional significance for the neuron? Here, we reflect on these and other key questions that remain to be addressed in this expanding field of biology.
Collapse
Affiliation(s)
- Alessandra Donato
- Clem Jones Centre for Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Konstantinos Kagias
- Department of Organismic and Evolutionary Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, U.S.A
| | - Yun Zhang
- Department of Organismic and Evolutionary Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, U.S.A
| | - Massimo A Hilliard
- Clem Jones Centre for Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| |
Collapse
|
46
|
Mechanisms of Axonal Sorting of Tau and Influence of the Axon Initial Segment on Tau Cell Polarity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1184:69-77. [DOI: 10.1007/978-981-32-9358-8_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
|
47
|
Kurochkina N, Bhaskar M, Yadav SP, Pant HC. Phosphorylation, Dephosphorylation, and Multiprotein Assemblies Regulate Dynamic Behavior of Neuronal Cytoskeleton: A Mini-Review. Front Mol Neurosci 2018; 11:373. [PMID: 30349458 PMCID: PMC6186834 DOI: 10.3389/fnmol.2018.00373] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 09/20/2018] [Indexed: 12/28/2022] Open
Abstract
Cellular localization, assembly and abnormal aggregation of neurofilaments depend on phosphorylation. Pathological processes associated with neurodegeneration exhibit aberrant accumulation of microtubule associated aggregated forms of hyperphosphorylated neuronal protein tau in cell bodies. These processes are critical for the disease progression in patients suffering from Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. In healthy cells, tau is localized in axons. Topographic regulation suggests that whereas the sites of synthesis of kinases and neurofilaments are the cell bodies, and sites of their functional assemblies are axons, phosphorylation/dephosphorylation are the key processes that arrange the molecules at their precise locations. Phosphorylation sites in the dynamic developmental and degenerative processes differ. Not all these processes are well understood. New advancements identify epigenetic factors involved in AD which account for the influence of age-related environment/genome interactions leading to the disease. Progress in proteomics highlights previously found major proteins and adds more to the list of those involved in AD. New key elements of specificity provide determinants of molecular recognition important for the assembly of macromolecular complexes. In this review, we discuss aberrant spatial distribution of neuronal polypeptides observed in neuropathies: aggregation, association with proteins of the neuronal cytoskeleton, and phosphorylation dependent dynamics. Particularly, we emphasize recent advancements in understanding the function and determinants of specific association of molecules involved in Alzheimer's disease with respect to the topographic regulation of phosphorylation in neuronal cytoskeleton and implications for the design of new therapies. Further, we address the role of various filament systems in maintenance of the shape, rigidity and dynamics of the cytoskeleton.
Collapse
Affiliation(s)
- Natalya Kurochkina
- Department of Biophysics, The School of Theoretical Modeling, Washington, DC, United States
| | - Manju Bhaskar
- Neuronal Cytoskeletal Protein Regulation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Sharda Prasad Yadav
- Neuronal Cytoskeletal Protein Regulation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Harish C. Pant
- Neuronal Cytoskeletal Protein Regulation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| |
Collapse
|
48
|
Mylvaganam SM, Grinstein S, Freeman SA. Picket-fences in the plasma membrane: functions in immune cells and phagocytosis. Semin Immunopathol 2018; 40:605-615. [DOI: 10.1007/s00281-018-0705-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 12/20/2022]
|
49
|
Klinman E, Tokito M, Holzbaur ELF. CDK5-dependent activation of dynein in the axon initial segment regulates polarized cargo transport in neurons. Traffic 2018; 18:808-824. [PMID: 28941293 DOI: 10.1111/tra.12529] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 02/03/2023]
Abstract
The unique polarization of neurons depends on selective sorting of axonal and somatodendritic cargos to their correct compartments. Axodendritic sorting and filtering occurs within the axon initial segment (AIS). However, the underlying molecular mechanisms responsible for this filter are not well understood. Here, we show that local activation of the neuronal-specific kinase cyclin-dependent kinase 5 (CDK5) is required to maintain AIS integrity, as depletion or inhibition of CDK5 induces disordered microtubule polarity and loss of AIS cytoskeletal structure. Furthermore, CDK5-dependent phosphorylation of the dynein regulator Ndel1 is required for proper re-routing of mislocalized somatodendritic cargo out of the AIS; inhibition of this pathway induces profound mis-sorting defects. While inhibition of the CDK5-Ndel1-Lis1-dynein pathway alters both axonal microtubule polarity and axodendritic sorting, we found that these defects occur on distinct timescales; brief inhibition of dynein disrupts axonal cargo sorting before loss of microtubule polarity becomes evident. Together, these studies identify CDK5 as a master upstream regulator of trafficking in vertebrate neurons, required for both AIS microtubule organization and polarized dynein-dependent sorting of axodendritic cargos, and support an ongoing and essential role for dynein at the AIS.
Collapse
Affiliation(s)
- Eva Klinman
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Mariko Tokito
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Erika L F Holzbaur
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
50
|
Balasanyan V, Watanabe K, Dempsey WP, Lewis TL, Trinh LA, Arnold DB. Structure and Function of an Actin-Based Filter in the Proximal Axon. Cell Rep 2018; 21:2696-2705. [PMID: 29212018 DOI: 10.1016/j.celrep.2017.11.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 08/24/2017] [Accepted: 11/13/2017] [Indexed: 10/18/2022] Open
Abstract
The essential organization of microtubules within neurons has been described; however, less is known about how neuronal actin is arranged and the functional implications of its arrangement. Here, we describe, in live cells, an actin-based structure in the proximal axon that selectively prevents some proteins from entering the axon while allowing the passage of others. Concentrated patches of actin in proximal axons are present shortly after axonal specification in rat and zebrafish neurons imaged live, and they mark positions where anterogradely traveling vesicles carrying dendritic proteins halt and reverse. Patches colocalize with the ARP2/3 complex, and when ARP2/3-mediated nucleation is blocked, a dendritic protein mislocalizes to the axon. Patches are highly dynamic, with few persisting longer than 30 min. In neurons in culture and in vivo, actin appears to form a contiguous, semipermeable barrier, despite its apparently sparse distribution, preventing axonal localization of constitutively active myosin Va but not myosin VI.
Collapse
Affiliation(s)
- Varuzhan Balasanyan
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Kaori Watanabe
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - William P Dempsey
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Tommy L Lewis
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Le A Trinh
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Don B Arnold
- Department of Biology, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
| |
Collapse
|