1
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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.
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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
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2
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Gonzalez-Hernandez AJ, Munguba H, Levitz J. Emerging modes of regulation of neuromodulatory G protein-coupled receptors. Trends Neurosci 2024:S0166-2236(24)00088-2. [PMID: 38862331 DOI: 10.1016/j.tins.2024.05.008] [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: 03/28/2024] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 06/13/2024]
Abstract
In the nervous system, G protein-coupled receptors (GPCRs) control neuronal excitability, synaptic transmission, synaptic plasticity, and, ultimately, behavior through spatiotemporally precise initiation of a variety of signaling pathways. However, despite their critical importance, there is incomplete understanding of how these receptors are regulated to tune their signaling to specific neurophysiological contexts. A deeper mechanistic picture of neuromodulatory GPCR function is needed to fully decipher their biological roles and effectively harness them for the treatment of neurological and psychiatric disorders. In this review, we highlight recent progress in identifying novel modes of regulation of neuromodulatory GPCRs, including G protein- and receptor-targeting mechanisms, receptor-receptor crosstalk, and unique features that emerge in the context of chemical synapses. These emerging principles of neuromodulatory GPCR tuning raise critical questions to be tackled at the molecular, cellular, synaptic, and neural circuit levels in the future.
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Affiliation(s)
| | - Hermany Munguba
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA.
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3
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Boyer NP, Sharma R, Wiesner T, Delamare A, Pelletier F, Leterrier C, Roy S. Spectrin condensates provide a nidus for assembling the periodic axonal structure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.05.597638. [PMID: 38895400 PMCID: PMC11185721 DOI: 10.1101/2024.06.05.597638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Coordinated assembly of individual components into higher-order structures is a defining theme in biology, but underlying principles are not well-understood. In neurons, α/β spectrins, adducin, and actinfilaments assemble into a lattice wrapping underneath the axonal plasma membrane, but mechanistic events leading to this periodic axonal structure (PAS) are unclear. Visualizing PAS components in axons as they develop, we found focal patches in distal axons containing spectrins and adducin (but sparse actin filaments) with biophysical properties reminiscent of biomolecular condensation. Overexpressing spectrin-repeats - constituents of α/β-spectrins - in heterologous cells triggered condensate formation, and preventing association of βII-spectrin with actin-filaments/membranes also facilitated condensation. Finally, overexpressing condensate-triggering spectrin repeats in neurons before PAS establishment disrupted the lattice, presumably by competing with innate assembly, supporting a functional role for biomolecular condensation. We propose a condensation-assembly model where PAS components form focal phase-separated condensates that eventually unfurl into a stable lattice-structure by associating with subplasmalemmal actin. By providing local 'depots' of assembly parts, biomolecular condensation may play a wider role in the construction of intricate cytoskeletal structures.
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4
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Li H, Ye Q, Wang D, Shi B, Xu W, Zhang S, Han X, Zhang XY, Thompson GJ. Resting State Brain Networks under Inverse Agonist versus Complete Knockout of the Cannabinoid Receptor 1. ACS Chem Neurosci 2024; 15:1669-1683. [PMID: 38575140 PMCID: PMC11027912 DOI: 10.1021/acschemneuro.3c00804] [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: 12/13/2023] [Revised: 03/14/2024] [Accepted: 03/14/2024] [Indexed: 04/06/2024] Open
Abstract
The cannabinoid receptor 1 (CB1) is famous as the target of Δ9-tetrahydrocannabinol (THC), which is the active ingredient of marijuana. Suppression of CB1 is frequently suggested as a drug target or gene therapy for many conditions (e.g., obesity, Parkinson's disease). However, brain networks affected by CB1 remain elusive, and unanticipated psychological effects in a clinical trial had dire consequences. To better understand the whole brain effects of CB1 suppression we performed in vivo imaging on mice under complete knockout of the gene for CB1 (cnr1-/-) and also under the CB1 inverse agonist rimonabant. We examined white matter structural changes and brain function (network activity and directional uniformity) in cnr1-/- mice. In cnr1-/- mice, white matter (in both sexes) and functional directional uniformity (in male mice) were altered across the brain but network activity was largely unaltered. Conversely, under rimonabant, functional directional uniformity was not altered but network activity was altered in cortical regions, primarily in networks known to be altered by THC (e.g., neocortex, hippocampal formation). However, rimonabant did not alter many brain regions found in both our cnr1-/- results and previous behavioral studies of cnr1-/- mice (e.g., thalamus, infralimbic area). This suggests that chronic loss of cnr1 is substantially different from short-term suppression, subtly rewiring the brain but largely maintaining the network activity. Our results help explain why pathological mutations in CB1 (e.g., chronic pain) do not always provide insight into the side effects of CB1 suppression (e.g., clinical depression), and thus urge more preclinical studies for any drugs that suppress CB1.
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Affiliation(s)
- Hui Li
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
| | - Qiong Ye
- High
Magnetic Field Laboratory, Hefei Institutes
of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Da Wang
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Bowen Shi
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Wenjing Xu
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
| | - Shuning Zhang
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Xiaoyang Han
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
| | - Xiao-Yong Zhang
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
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5
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Fessl T, Majellaro M, Bondar A. Microscopy and spectroscopy approaches to study GPCR structure and function. Br J Pharmacol 2023. [PMID: 38087925 DOI: 10.1111/bph.16297] [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: 06/30/2023] [Revised: 11/03/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
The GPCR signalling cascade is a key pathway responsible for the signal transduction of a multitude of physical and chemical stimuli, including light, odorants, neurotransmitters and hormones. Understanding the structural and functional properties of the GPCR cascade requires direct observation of signalling processes in high spatial and temporal resolution, with minimal perturbation to endogenous systems. Optical microscopy and spectroscopy techniques are uniquely suited to this purpose because they excel at multiple spatial and temporal scales and can be used in living objects. Here, we review recent developments in microscopy and spectroscopy technologies which enable new insights into GPCR signalling. We focus on advanced techniques with high spatial and temporal resolution, single-molecule methods, labelling strategies and approaches suitable for endogenous systems and large living objects. This review aims to assist researchers in choosing appropriate microscopy and spectroscopy approaches for a variety of applications in the study of cellular signalling.
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Affiliation(s)
- Tomáš Fessl
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | | | - Alexey Bondar
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Laboratory of Microscopy and Histology, Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
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6
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Ciralli B, Malfatti T, Lima TZ, Silva SRB, Cederroth CR, Leao KE. Alterations of auditory sensory gating in mice with noise-induced tinnitus treated with nicotine and cannabis extract. J Psychopharmacol 2023; 37:1116-1131. [PMID: 37837354 DOI: 10.1177/02698811231200879] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2023]
Abstract
Tinnitus is a phantom sound perception affecting both auditory and limbic structures. The mechanisms of tinnitus remain unclear and it is debatable whether tinnitus alters attention to sound and the ability to inhibit repetitive sounds, a phenomenon also known as auditory gating. Here we investigate if noise exposure interferes with auditory gating and whether natural extracts of cannabis or nicotine could improve auditory pre-attentional processing in noise-exposed mice. We used 22 male C57BL/6J mice divided into noise-exposed (exposed to a 9-11 kHz narrow band noise for 1 h) and sham (no sound during noise exposure) groups. Hearing thresholds were measured using auditory brainstem responses, and tinnitus-like behavior was assessed using Gap prepulse inhibition of acoustic startle. After noise exposure, mice were implanted with multi-electrodes in the dorsal hippocampus to assess auditory event-related potentials in response to paired clicks. The results showed that mice with tinnitus-like behavior displayed auditory gating of repetitive clicks, but with larger amplitudes and longer latencies of the N40 component of the aERP waveform. The combination of cannabis extract and nicotine improved the auditory gating ratio in noise-exposed mice without permanent hearing threshold shifts. Lastly, the longer latency of the N40 component appears due to an increased sensitivity to cannabis extract in noise-exposed mice compared to sham mice. The study suggests that the altered central plasticity in tinnitus is more sensitive to the combined actions on the cholinergic and the endocannabinoid systems. Overall, the findings contribute to a better understanding of pharmacological modulation of auditory sensory gating.
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Affiliation(s)
- Barbara Ciralli
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Thawann Malfatti
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, Brazil
- Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Sweden
| | - Thiago Z Lima
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, Brazil
- Department of Applied Mathematics and Statistics, Exact and Earth Sciences Center, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | | | - Christopher R Cederroth
- Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Sweden
- Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany
| | - Katarina E Leao
- Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, Brazil
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7
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Reece AS, Hulse GK. Perturbation of 3D nuclear architecture, epigenomic aging and dysregulation, and cannabinoid synaptopathy reconfigures conceptualization of cannabinoid pathophysiology: part 2-Metabolome, immunome, synaptome. Front Psychiatry 2023; 14:1182536. [PMID: 37854446 PMCID: PMC10579598 DOI: 10.3389/fpsyt.2023.1182536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023] Open
Abstract
The second part of this paper builds upon and expands the epigenomic-aging perspective presented in Part 1 to describe the metabolomic and immunomic bases of the epigenomic-aging changes and then considers in some detail the application of these insights to neurotoxicity, neuronal epigenotoxicity, and synaptopathy. Cannabinoids are well-known to have bidirectional immunomodulatory activities on numerous parts of the immune system. Immune perturbations are well-known to impact the aging process, the epigenome, and intermediate metabolism. Cannabinoids also impact metabolism via many pathways. Metabolism directly impacts immune, genetic, and epigenetic processes. Synaptic activity, synaptic pruning, and, thus, the sculpting of neural circuits are based upon metabolic, immune, and epigenomic networks at the synapse, around the synapse, and in the cell body. Many neuropsychiatric disorders including depression, anxiety, schizophrenia, bipolar affective disorder, and autistic spectrum disorder have been linked with cannabis. Therefore, it is important to consider these features and their complex interrelationships in reaching a comprehensive understanding of cannabinoid dependence. Together these findings indicate that cannabinoid perturbations of the immunome and metabolome are important to consider alongside the well-recognized genomic and epigenomic perturbations and it is important to understand their interdependence and interconnectedness in reaching a comprehensive appreciation of the true nature of cannabinoid pathophysiology. For these reasons, a comprehensive appreciation of cannabinoid pathophysiology necessitates a coordinated multiomics investigation of cannabinoid genome-epigenome-transcriptome-metabolome-immunome, chromatin conformation, and 3D nuclear architecture which therefore form the proper mechanistic underpinning for major new and concerning epidemiological findings relating to cannabis exposure.
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Affiliation(s)
- Albert Stuart Reece
- Division of Psychiatry, University of Western Australia, Crawley, WA, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Gary Kenneth Hulse
- Division of Psychiatry, University of Western Australia, Crawley, WA, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
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8
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Martinez Ramirez CE, Ruiz-Pérez G, Stollenwerk TM, Behlke C, Doherty A, Hillard CJ. Endocannabinoid signaling in the central nervous system. Glia 2023; 71:5-35. [PMID: 36308424 PMCID: PMC10167744 DOI: 10.1002/glia.24280] [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: 02/01/2022] [Revised: 09/02/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022]
Abstract
It is hard to overestimate the influence of the endocannabinoid signaling (ECS) system on central nervous system (CNS) function. In the 40 years since cannabinoids were found to trigger specific cell signaling cascades, studies of the ECS system continue to cause amazement, surprise, and confusion! CB1 cannabinoid receptors are expressed widely in the CNS and regulate cell-cell communication via effects on the release of both neurotransmitters and gliotransmitters. CB2 cannabinoid receptors are difficult to detect in the CNS but seem to "punch above their weight" as compounds targeting these receptors have significant effects on inflammatory state and behavior. Positive and negative allosteric modulators for both receptors have been identified and examined in preclinical studies. Concentrations of the endocannabinoid ligands, N-arachidonoylethanolamine and 2-arachidonoylglycerol (2-AG), are regulated by a combination of enzymatic synthesis and degradation and inhibitors of these processes are available and making their way into clinical trials. Importantly, ECS regulates many essential brain functions, including regulation of reward, anxiety, inflammation, motor control, and cellular development. While the field is on the cusp of preclinical discoveries providing impactful clinical and therapeutic insights into many CNS disorders, there is still much to be learned about this remarkable and versatile modulatory system.
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Affiliation(s)
- César E Martinez Ramirez
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Gonzalo Ruiz-Pérez
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Todd M Stollenwerk
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Christina Behlke
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Ashley Doherty
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Cecilia J Hillard
- Neuroscience Research Center and Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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9
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Zöldi M, Katona I. STORM Super-Resolution Imaging of CB 1 Receptors in Tissue Preparations. Methods Mol Biol 2023; 2576:437-451. [PMID: 36152208 DOI: 10.1007/978-1-0716-2728-0_36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Single-molecule localization microscopy (SMLM) opened new possibilities to study the spatial arrangement of molecular distribution and disease-associated redistribution at a previously unprecedented resolution that was not achievable with optical microscopy approaches. Recent discoveries based on SMLM techniques uncovered specific nanoscale organizational principles of signaling proteins in several biological systems including the chemical synapses in the brain. Emerging data suggest that the spatial arrangement of the molecular players of the endocannabinoid system is also precisely regulated at the nanoscale level in synapses and in other neuronal and glial subcellular compartments. The precise nanoscale distribution pattern is likely to be important to subserve several specific signaling functions of this important messenger system in a cell-type- and subcellular domain-specific manner.STochastic Optical Reconstruction Microscopy (STORM) is an especially suitable SMLM modality for cell-type-specific nanoscale molecular imaging due to its compatibility with traditional diffraction-limited microscopy approaches and classical staining methods. Here, we describe a detailed protocol for STORM imaging in mouse brain tissue samples with a focus on the CB1 cannabinoid receptor, one of the most abundant synaptic receptors in the brain. We also summarize important conceptual and methodical details that are essential for the valid interpretation of single-molecule localization microscopy data.
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Affiliation(s)
- Miklós Zöldi
- Department of Psychological and Brain Sciences, Indiana University, IN, USA
- School of Ph.D. Studies, Semmelweis University, Budapest, Hungary
| | - István Katona
- Department of Psychological and Brain Sciences, Indiana University, IN, USA.
- Momentum Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.
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10
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Cytoskeletal assembly in axonal outgrowth and regeneration analyzed on the nanoscale. Sci Rep 2022; 12:14387. [PMID: 35999340 PMCID: PMC9399097 DOI: 10.1038/s41598-022-18562-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/16/2022] [Indexed: 11/08/2022] Open
Abstract
The axonal cytoskeleton is organized in a highly periodic structure, the membrane-associated periodic skeleton (MPS), which is essential to maintain the structure and function of the axon. Here, we use stimulated emission depletion microscopy of primary rat cortical neurons in microfluidic chambers to analyze the temporal and spatial sequence of MPS formation at the distal end of growing axons and during regeneration after axotomy. We demonstrate that the MPS does not extend continuously into the growing axon but develops from patches of periodic βII-spectrin arrangements that grow and coalesce into a continuous scaffold. We estimate that the underlying sequence of assembly, elongation, and subsequent coalescence of periodic βII-spectrin patches takes around 15 h. Strikingly, we find that development of the MPS occurs faster in regenerating axons after axotomy and note marked differences in the morphology of the growth cone and adjacent axonal regions between regenerating and unlesioned axons. Moreover, we find that inhibition of the spectrin-cleaving enzyme calpain accelerates MPS formation in regenerating axons and increases the number of regenerating axons after axotomy. Taken together, we provide here a detailed nanoscale analysis of MPS development in growing axons.
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11
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Liu W, Padhi A, Zhang X, Narendran J, Anastasio MA, Nain AS, Irudayaraj J. Dynamic Heterochromatin States in Anisotropic Nuclei of Cells on Aligned Nanofibers. ACS NANO 2022; 16:10754-10767. [PMID: 35803582 PMCID: PMC9332347 DOI: 10.1021/acsnano.2c02660] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The cancer cell nucleus deforms as it invades the interstitial spaces in tissues and the tumor microenvironment. While alteration of the chromatin structure in a deformed nucleus is expected and documented, the chromatin structure in the nuclei of cells on aligned matrices has not been elucidated. In this work we elucidate the spatiotemporal organization of heterochromatin in the elongated nuclei of cells on aligned nanofibers with stimulated emission depletion nanoscopy and fluorescence correlation spectroscopy. We show that the anisotropy of nuclei is sufficient to drive H3K9me3-heterochromatin alterations, with enhanced H3K9me3 nanocluster compaction and aggregation states that otherwise are indistinguishable from diffraction-limited microscopy. We interrogated the higher-order heterochromatin structures within major chromatin compartments in anisotropic nuclei and discovered a wider spatial dispersion of nanodomain clusters in the nucleoplasm and condensed larger nanoclusters near the periphery and pericentromeric heterochromatin. Upon examining the spatiotemporal dynamics of heterochromatin in anisotropic nuclei, we observed reduced mobility of the constitutive heterochromatin mark H3K9me3 and the associated heterochromatin protein 1 (HP1α) at the nucleoplasm and periphery regions, correlating with increased viscosity and changes in gene expression. Since heterochromatin remodeling is crucial to genome integrity, our results reveal an unconventional H3K9me3 heterochromatin distribution, providing cues to an altered chromatin state due to perturbations of the nuclei in aligned fiber configurations.
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Affiliation(s)
- Wenjie Liu
- Department
of Bioengineering, University of Illinois
at Urbana−Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States
- Biomedical
Research Center, Mills Breast Cancer Institute, Cancer Center at Illinois,
Micro and Nanotechnology Laboratory, Beckman
Institute, Carl Woese Institute for Genomic Biology, Urbana, Illinois 61801, United States
| | - Abinash Padhi
- Department
of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Xiaohui Zhang
- Department
of Bioengineering, University of Illinois
at Urbana−Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States
| | - Jairaj Narendran
- Department
of Bioengineering, University of Illinois
at Urbana−Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States
| | - Mark A. Anastasio
- Department
of Bioengineering, University of Illinois
at Urbana−Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States
| | - Amrinder S. Nain
- Department
of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Joseph Irudayaraj
- Department
of Bioengineering, University of Illinois
at Urbana−Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States
- Biomedical
Research Center, Mills Breast Cancer Institute, Cancer Center at Illinois,
Micro and Nanotechnology Laboratory, Beckman
Institute, Carl Woese Institute for Genomic Biology, Urbana, Illinois 61801, United States
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12
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Dudok B, Soltesz I. Imaging the endocannabinoid signaling system. J Neurosci Methods 2022; 367:109451. [PMID: 34921843 PMCID: PMC8734437 DOI: 10.1016/j.jneumeth.2021.109451] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 10/18/2021] [Accepted: 12/13/2021] [Indexed: 02/03/2023]
Abstract
The endocannabinoid (eCB) system is one of the most widespread neuromodulatory systems in the mammalian brain, with a multifaceted role in functions ranging from development to synaptic plasticity. Endocannabinoids are synthesized on demand from membrane lipid precursors, and act primarily on a single G-protein coupled receptor type, CB1, to carry out diverse functions. Despite the importance of the eCB system both in healthy brain function and in disease, critically important details of eCB signaling remained unknown. How eCBs are released from the membrane, how these lipid molecules are transported between cells, and how the distribution of their receptors is controlled, remained elusive. Recent advances in optical microscopy methods and biosensor engineering may open up new avenues for studying eCB signaling. We summarize applications of superresolution microscopy using single molecule localization to reveal distinct patterns of nanoscale CB1 distribution in neuronal axons and axon terminals. We review single particle tracking studies using quantum dots that allowed visualizing CB1 trajectories. We highlight the recent development of fluorescent eCB biosensors, that revealed spatiotemporally specific eCB release in live cells and live animals. Finally, we discuss future directions where method development may help to advance a precise understanding of eCB signaling.
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Affiliation(s)
- Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
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Wang T, Meunier FA. Live-Cell Superresolution Imaging of Retrograde Axonal Trafficking Using Pulse-Chase Labeling in Cultured Hippocampal Neurons. Methods Mol Biol 2022; 2473:101-128. [PMID: 35819762 DOI: 10.1007/978-1-0716-2209-4_9] [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: 06/15/2023]
Abstract
The entanglement of long axons found in cultured dissociated hippocampal neurons restricts the analysis of the machinery underlying directed axonal trafficking. Further, hippocampal neurons exhibit "en passant" presynapses that may confound the analysis of long-range retrograde axonal transport. To solve these issues, we and others have developed microfluid-based methods to specifically follow the fates of the retrograde axonal cargoes following pulse-chase labeling by super-resolution live-cell imaging, and automatically tracking their directed transport and analyzing their kinetical properties. These methods have allowed us to visualize the trafficking of fluorescently tagged signaling endosomes and autophagosomes derived from axonal terminals and resolve their localizations and movements with high spatial and temporal accuracy. In this chapter, we describe how to use a commercially available microfluidic device to enable the labeling and tracking of retrograde axonal carriers, including (1) how to culture and transfect rat hippocampal neurons in the microfluidic device; (2) how to perform pulse-chase to label specific populations of retrograde axonal carriers; and (3) how to conduct the automatic tracking and data analysis using open-source software.
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Affiliation(s)
- Tong Wang
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China.
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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14
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Liu W, Mohan SP, Nagaraj NR, Sundar Jaganathan S, Wen Y, Ramasubramanyan S, Irudayaraj J. Epigenetic alterations associated with dexamethasone sodium phosphate through DNMT and TET in RPE cells. Mol Vis 2021; 27:643-655. [PMID: 34924744 PMCID: PMC8645185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 11/18/2021] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To elucidate the mechanism behind epigenetic alteration associated with dexamethasone (DEX) sodium phosphate treatment. METHODS We performed enzyme-linked immunosorbent assay to quantify changes in global DNA methylation and hydroxymethylation, quantitative real-time PCR (qRT-PCR) of the DNA methylation- and hydroxymethylation-related gene, in vitro DNA methyltransferase (DNMT) enzymatic activity assays with purified DNMTs, and DNA hydroxymethylation pattern with super-resolution imaging. RESULTS We identified global DNA hypomethylation and hyper-hydroxymethylation upon DEX treatment, associated with aberrant mRNA expression levels of DNMT and ten-eleven translocation (TET) proteins. Additionally, DEX exposure could directly hinder DNMT activities. CONCLUSIONS We showed that DEX-induced epigenetic alterations are linked to aberrant DNMT and TET expression, potentially through an essential role of DNMT.
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Affiliation(s)
- Wenjie Liu
- Department of Bioengineering, Cancer Center at Illinois, Micro and Nanotechnology Laboratory. University of Illinois at Urbana-Champaign, Urbana, IL,Biomedical Research Center in Mills Breast Cancer Institute, Carles Foundation Hospital, Urbana, IL
| | - Sruthi Priya Mohan
- R.S. Mehta Jain Department of Biochemistry and Cell Biology, KBIRVO, Vision Research Foundation, Chennai, TN, India
| | | | - Shyam Sundar Jaganathan
- R.S. Mehta Jain Department of Biochemistry and Cell Biology, KBIRVO, Vision Research Foundation, Chennai, TN, India
| | - Yi Wen
- Department of Bioengineering, Cancer Center at Illinois, Micro and Nanotechnology Laboratory. University of Illinois at Urbana-Champaign, Urbana, IL,Biomedical Research Center in Mills Breast Cancer Institute, Carles Foundation Hospital, Urbana, IL
| | - Sharada Ramasubramanyan
- R.S. Mehta Jain Department of Biochemistry and Cell Biology, KBIRVO, Vision Research Foundation, Chennai, TN, India
| | - Joseph Irudayaraj
- Department of Bioengineering, Cancer Center at Illinois, Micro and Nanotechnology Laboratory. University of Illinois at Urbana-Champaign, Urbana, IL,Biomedical Research Center in Mills Breast Cancer Institute, Carles Foundation Hospital, Urbana, IL
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Jullié D, Valbret Z, Stoeber M. Optical tools to study the subcellular organization of GPCR neuromodulation. J Neurosci Methods 2021; 366:109408. [PMID: 34763022 DOI: 10.1016/j.jneumeth.2021.109408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 10/11/2021] [Accepted: 11/03/2021] [Indexed: 12/29/2022]
Abstract
Modulation of neuronal circuit activity is key to information processing in the brain. G protein-coupled receptors (GPCRs), the targets of most neuromodulatory ligands, show extremely diverse expression patterns in neurons and receptors can be localized in various sub-neuronal membrane compartments. Upon activation, GPCRs promote signaling cascades that alter the level of second messengers, drive phosphorylation changes, modulate ion channel function, and influence gene expression, all of which critically impact neuron physiology. Because of its high degree of complexity, this form of interneuronal communication has remained challenging to integrate into our conceptual understanding of brain function. Recent technological advances in fluorescence microscopy and the development of optical biosensors now allow investigating neuromodulation with unprecedented resolution on the level of individual cells. In this review, we will highlight recent imaging techniques that enable determining the precise localization of GPCRs in neurons, with specific focus on the subcellular and nanoscale level. Downstream of receptors, we describe novel conformation-specific biosensors that allow for real-time monitoring of GPCR activation and of distinct signal transduction events in neurons. Applying these new tools has the potential to provide critical insights into the function and organization of GPCRs in neuronal cells and may help decipher the molecular and cellular mechanisms that underlie neuromodulation.
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Affiliation(s)
- Damien Jullié
- Department of Psychiatry, University of California San Francisco, San Francisco, USA.
| | - Zoé Valbret
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Miriam Stoeber
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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Pan X, Zhou Y, Hotulainen P, Meunier FA, Wang T. The axonal radial contractility: Structural basis underlying a new form of neural plasticity. Bioessays 2021; 43:e2100033. [PMID: 34145916 DOI: 10.1002/bies.202100033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 12/25/2022]
Abstract
Axons are the longest cellular structure reaching over a meter in the case of human motor axons. They have a relatively small diameter and contain several cytoskeletal elements that mediate both material and information exchange within neurons. Recently, a novel type of axonal plasticity, termed axonal radial contractility, has been unveiled. It is represented by dynamic and transient diameter changes of the axon shaft to accommodate the passages of large organelles. Mechanisms underpinning this plasticity are not fully understood. Here, we first summarised recent evidence of the functional relevance for axon radial contractility, then discussed the underlying structural basis, reviewing nanoscopic evidence of the subtle changes. Two models are proposed to explain how actomyosin rings are organised. Possible roles of non-muscle myosin II (NM-II) in axon degeneration are discussed. Finally, we discuss the concept of periodic functional nanodomains, which could sense extracellular cues and coordinate the axonal responses. Also see the video abstract here: https://youtu.be/ojCnrJ8RCRc.
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Affiliation(s)
- Xiaorong Pan
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Yimin Zhou
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Tong Wang
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
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17
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Putting the axonal periodic scaffold in order. Curr Opin Neurobiol 2021; 69:33-40. [PMID: 33450534 DOI: 10.1016/j.conb.2020.12.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 01/01/2023]
Abstract
Neurons rely on a unique organization of their cytoskeleton to build, maintain and transform their extraordinarily intricate shapes. After decades of research on the neuronal cytoskeleton, it is exciting that novel assemblies are still discovered thanks to progress in cellular imaging methods. Indeed, super-resolution microscopy has revealed that axons are lined with a periodic scaffold of actin rings, spaced every 190nm by spectrins. Determining the architecture, composition, dynamics, and functions of this membrane-associated periodic scaffold is a current conceptual and technical challenge, as well as a very active area of research. This short review aims at summarizing the latest research on the axonal periodic scaffold, highlighting recent progress and open questions.
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