1
|
Pan X, Hu Y, Lei G, Wei Y, Li J, Luan T, Zhang Y, Chu Y, Feng Y, Zhan W, Zhao C, Meunier FA, Liu Y, Li Y, Wang T. Actomyosin-II protects axons from degeneration induced by mild mechanical stress. J Cell Biol 2024; 223:e202206046. [PMID: 38713825 PMCID: PMC11076810 DOI: 10.1083/jcb.202206046] [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: 06/19/2022] [Revised: 06/16/2023] [Accepted: 04/09/2024] [Indexed: 05/09/2024] Open
Abstract
Whether, to what extent, and how the axons in the central nervous system (CNS) can withstand sudden mechanical impacts remain unclear. By using a microfluidic device to apply controlled transverse mechanical stress to axons, we determined the stress levels that most axons can withstand and explored their instant responses at nanoscale resolution. We found mild stress triggers a highly reversible, rapid axon beading response, driven by actomyosin-II-dependent dynamic diameter modulations. This mechanism contributes to hindering the long-range spread of stress-induced Ca2+ elevations into non-stressed neuronal regions. Through pharmacological and molecular manipulations in vitro, we found that actomyosin-II inactivation diminishes the reversible beading process, fostering progressive Ca2+ spreading and thereby increasing acute axonal degeneration in stressed axons. Conversely, upregulating actomyosin-II activity prevents the progression of initial injury, protecting stressed axons from acute degeneration both in vitro and in vivo. Our study unveils the periodic actomyosin-II in axon shafts cortex as a novel protective mechanism, shielding neurons from detrimental effects caused by mechanical stress.
Collapse
Affiliation(s)
- Xiaorong Pan
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yiqing Hu
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Gaowei Lei
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences China, Shanghai, China
| | - Yaxuan Wei
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences China, Shanghai, China
| | - Jie Li
- Division of Chemistry and Physical Biology, School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
- Shanghai Clinical Research and Trial Center, Shanghai, China
| | - Tongshu Luan
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yunfan Zhang
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences China, Shanghai, China
| | - Yuanyuan Chu
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yu Feng
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Wenrong Zhan
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chunxia Zhao
- School of Chemical Engineering, The University of Adelaide, Adelaide, Australia
| | - Frédéric A. Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Yifan Liu
- Division of Chemistry and Physical Biology, School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
- Shanghai Clinical Research and Trial Center, Shanghai, China
| | - Yi Li
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences China, Shanghai, China
| | - Tong Wang
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| |
Collapse
|
2
|
Campbell KR, Hallada LP, Huang YS, Solecki DJ. From Blur to Brilliance: The Ascendance of Advanced Microscopy in Neuronal Cell Biology. Annu Rev Neurosci 2024; 47:235-253. [PMID: 38608643 DOI: 10.1146/annurev-neuro-111020-090208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2024]
Abstract
The intricate network of the brain's neurons and synapses poses unparalleled challenges for research, distinct from other biological studies. This is particularly true when dissecting how neurons and their functional units work at a cell biological level. While traditional microscopy has been foundational, it was unable to reveal the deeper complexities of neural interactions. However, an imaging renaissance has transformed our capabilities. Advancements in light and electron microscopy, combined with correlative imaging, now achieve unprecedented resolutions, uncovering the most nuanced neural structures. Maximizing these tools requires more than just technical proficiency. It is crucial to align research aims, allocate resources wisely, and analyze data effectively. At the heart of this evolution is interdisciplinary collaboration, where various experts come together to translate detailed imagery into significant biological insights. This review navigates the latest developments in microscopy, underscoring both the promise of and prerequisites for bending this powerful tool set to understanding neuronal cell biology.
Collapse
Affiliation(s)
- Kirby R Campbell
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - Liam P Hallada
- St. Jude Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - Yu-Shan Huang
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| | - David J Solecki
- Neuronal Cell Biology Division, Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA;
| |
Collapse
|
3
|
Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling Difficult Cryo-ET Samples: A Study with Primary Neurons from Drosophila melanogaster. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:2127-2148. [PMID: 37966978 PMCID: PMC11168236 DOI: 10.1093/micmic/ozad125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/01/2023] [Accepted: 10/18/2023] [Indexed: 11/17/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons having been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
Collapse
Affiliation(s)
- Joseph Y. Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jie E. Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Josephine W. Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI 49006, USA
| | - Lauren A. English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Sihui Z. Yang
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI 53715, USA
| |
Collapse
|
4
|
Mays KC, Haiman JH, Janušonis S. An experimental platform for stochastic analyses of single serotonergic fibers in the mouse brain. Front Neurosci 2023; 17:1241919. [PMID: 37869509 PMCID: PMC10587471 DOI: 10.3389/fnins.2023.1241919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 09/21/2023] [Indexed: 10/24/2023] Open
Abstract
The self-organization of the serotonergic matrix, a massive axon meshwork in all vertebrate brains, is driven by the structural and dynamical properties of its constitutive elements. Each of these elements, a single serotonergic axon (fiber), has a unique trajectory and can be supported by a soma that executes one of the many available transcriptional programs. This "individuality" of serotonergic neurons necessitates the development of specialized methods for single-fiber analyses, both at the experimental and theoretical levels. We developed an integrated platform that facilitates experimental isolation of single serotonergic fibers in brain tissue, including regions with high fiber densities, and demonstrated the potential of their quantitative analyses based on stochastic modeling. Single fibers were visualized using two transgenic mouse models, one of which is the first implementation of the Brainbow toolbox in this system. The trajectories of serotonergic fibers were automatically traced in the three spatial dimensions with a novel algorithm, and their properties were captured with a single parameter associated with the directional von Mises-Fisher probability distribution. The system represents an end-to-end workflow that can be imported into various studies, including those investigating serotonergic dysfunction in brain disorders. It also supports new research directions inspired by single-fiber analyses in the serotonergic matrix, including supercomputing simulations and modeling in physics.
Collapse
Affiliation(s)
| | | | - Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| |
Collapse
|
5
|
Kim JY, Yang J, Mitchell JW, English LA, Wildonger J, Dent EW, Wright ER. Morphological Comparison of Primary Neurons Cryo-Preserved Under Varied Conditions. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:956-957. [PMID: 37613647 DOI: 10.1093/micmic/ozad067.477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Joseph Y Kim
- Department of Chemistry, UW-Madison, Madison, WI, United States
- Department of Biochemistry, UW-Madison, Madison, WI, United States
| | - Jae Yang
- Department of Biochemistry, UW-Madison, Madison, WI, United States
- Midwest Center for Cryo-Electron Tomography, UW-Madison, Madison, WI, United States
| | - Josephine W Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI, United States
| | - Lauren A English
- Neuroscience Training Program, UW-Madison, Madison, WI, United States
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, UCSD, La Jolla, CA, United States
| | - Erik W Dent
- Department of Neuroscience, UW-Madison, Madison, WI, United States
| | - Elizabeth R Wright
- Department of Biochemistry, UW-Madison, Madison, WI, United States
- Midwest Center for Cryo-Electron Tomography, UW-Madison, Madison, WI, United States
- Cryo-Electron Microscopy Research Center, UW-Madison, Madison, WI, United States
- Morgridge Institute for Research, UW-Madison, Madison, WI, United States
| |
Collapse
|
6
|
Griswold JM, Bonilla-Quintana M, Pepper R, Lee CT, Raychaudhuri S, Ma S, Gan Q, Syed S, Zhu C, Bell M, Suga M, Yamaguchi Y, Chéreau R, Nägerl UV, Knott G, Rangamani P, Watanabe S. Membrane mechanics dictate axonal morphology and function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.20.549958. [PMID: 37503105 PMCID: PMC10370128 DOI: 10.1101/2023.07.20.549958] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Axons are thought to be ultrathin membrane cables of a relatively uniform diameter, designed to conduct electrical signals, or action potentials. Here, we demonstrate that unmyelinated axons are not simple cylindrical tubes. Rather, axons have nanoscopic boutons repeatedly along their length interspersed with a thin cable with a diameter of ∼60 nm like pearls-on-a-string. These boutons are only ∼200 nm in diameter and do not have synaptic contacts or a cluster of synaptic vesicles, hence non-synaptic. Our in silico modeling suggests that axon pearling can be explained by the mechanical properties of the membrane including the bending modulus and tension. Consistent with modeling predictions, treatments that disrupt these parameters like hyper- or hypo-tonic solutions, cholesterol removal, and non-muscle myosin II inhibition all alter the degree of axon pearling, suggesting that axon morphology is indeed determined by the membrane mechanics. Intriguingly, neuronal activity modulates the cholesterol level of plasma membrane, leading to shrinkage of axon pearls. Consequently, the conduction velocity of action potentials becomes slower. These data reveal that biophysical forces dictate axon morphology and function and that modulation of membrane mechanics likely underlies plasticity of unmyelinated axons.
Collapse
|
7
|
Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling difficult cryo-ET samples: A study with primary neurons from Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548468. [PMID: 37502991 PMCID: PMC10369871 DOI: 10.1101/2023.07.10.548468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
Collapse
Affiliation(s)
- Joseph Y. Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jie E. Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Josephine W. Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI, 49006, USA
| | - Lauren A. English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Sihui Z. Yang
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI, 53715, USA
| |
Collapse
|
8
|
Hingorani M, Viviani AML, Sanfilippo JE, Janušonis S. High-resolution spatiotemporal analysis of single serotonergic axons in an in vitro system. Front Neurosci 2022; 16:994735. [PMID: 36353595 PMCID: PMC9638127 DOI: 10.3389/fnins.2022.994735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/28/2022] [Indexed: 12/04/2022] Open
Abstract
Vertebrate brains have a dual structure, composed of (i) axons that can be well-captured with graph-theoretical methods and (ii) axons that form a dense matrix in which neurons with precise connections operate. A core part of this matrix is formed by axons (fibers) that store and release 5-hydroxytryptamine (5-HT, serotonin), an ancient neurotransmitter that supports neuroplasticity and has profound implications for mental health. The self-organization of the serotonergic matrix is not well understood, despite recent advances in experimental and theoretical approaches. In particular, individual serotonergic axons produce highly stochastic trajectories, fundamental to the construction of regional fiber densities, but further advances in predictive computer simulations require more accurate experimental information. This study examined single serotonergic axons in culture systems (co-cultures and monolayers), by using a set of complementary high-resolution methods: confocal microscopy, holotomography (refractive index-based live imaging), and super-resolution (STED) microscopy. It shows that serotonergic axon walks in neural tissue may strongly reflect the stochastic geometry of this tissue and it also provides new insights into the morphology and branching properties of serotonergic axons. The proposed experimental platform can support next-generation analyses of the serotonergic matrix, including seamless integration with supercomputing approaches.
Collapse
|