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Heffernan KS, Martinez I, Jaeger D, Khakh BS, Smith Y, Galvan A. Scaled Complexity of Mammalian Astrocytes: Insights From Mouse and Macaque. J Comp Neurol 2024; 532:e25665. [PMID: 39235147 PMCID: PMC11378921 DOI: 10.1002/cne.25665] [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: 12/15/2023] [Revised: 06/10/2024] [Accepted: 08/06/2024] [Indexed: 09/06/2024]
Abstract
Astrocytes intricately weave within the neuropil, giving rise to characteristic bushy morphologies. Pioneering studies suggested that primate astrocytes are more complex due to increased branch numbers and territory size compared to rodent counterparts. However, there has been no comprehensive comparison of astrocyte morphology across species. We employed several techniques to investigate astrocyte morphology and directly compared them between mice and rhesus macaques in cortical and subcortical regions. We assessed astrocyte density, territory size, branching structure, fine morphological complexity, and interactions with neuronal synapses using a combination of techniques, including immunohistochemistry, adeno-associated virus-mediated transduction of astrocytes, diOlistics, confocal imaging, and electron microscopy. We found significant morphological similarities between primate and rodent astrocytes, suggesting that astrocyte structure has scaled with evolution. Our findings show that primate astrocytes are larger and more numerous than those in rodents but contest the view that primate astrocytes are morphologically far more complex.
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Affiliation(s)
- Kate S Heffernan
- Division of Neuropharmacology and Neurological Disorders, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia, USA
| | | | - Dieter Jaeger
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia, USA
- Department of Biology, Emory University, Atlanta, Georgia, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Yoland Smith
- Division of Neuropharmacology and Neurological Disorders, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia, USA
- Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Adriana Galvan
- Division of Neuropharmacology and Neurological Disorders, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia, USA
- Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia, USA
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Kawabata H, Konno A, Matsuzaki Y, Sato Y, Kawachi M, Aoki R, Tsutsumi S, Togai S, Kobayashi R, Horii T, Hatada I, Hirai H. Improving cell-specific recombination using AAV vectors in the murine CNS by capsid and expression cassette optimization. Mol Ther Methods Clin Dev 2024; 32:101185. [PMID: 38282896 PMCID: PMC10811426 DOI: 10.1016/j.omtm.2024.101185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 01/04/2024] [Indexed: 01/30/2024]
Abstract
The production of cell-type- and age-specific genetically modified mice is a powerful approach for unraveling unknown gene functions. Here, we present a simple and timesaving method that enables adeno-associated virus (AAV)-mediated cell-type- and age-specific recombination in floxed mice. To achieve astrocyte-specific recombination in floxed Ai14 reporter mice, we intravenously injected blood-brain barrier-penetrating AAV-PHP.eB vectors expressing Cre recombinase (Cre) using the astrocyte-specific mouse glial fibrillary acidic protein (mGfaABC1D) promoter. However, we observed nonspecific neuron-predominant transduction despite the use of an astrocyte-specific promoter. We speculated that subtle but continuous Cre expression in nonastrocytic cells triggers recombination, and that excess production of Cre in astrocytes inhibits recombination by forming Cre-DNA aggregates. Here, we resolved this paradoxical event by dividing a single AAV into two mGfaABC1D-promoter-driven AAV vectors, one expressing codon-optimized flippase (FlpO) and another expressing flippase recognition target-flanked rapidly degrading Cre (dCre), together with switching the neuron-tropic PHP.eB capsid to astrocyte-tropic AAV-F. Moreover, we found that the FlpO-dCre system with a target cell-tropic capsid can also function in neuron-targeting recombination in floxed mice.
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Affiliation(s)
- Hayato Kawabata
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Ayumu Konno
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
- Viral Vector Core, Gunma University, Initiative for Advanced Research, Maebashi, Gunma 371-8511, Japan
| | - Yasunori Matsuzaki
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
- Viral Vector Core, Gunma University, Initiative for Advanced Research, Maebashi, Gunma 371-8511, Japan
| | - Yumika Sato
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Mika Kawachi
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Ryo Aoki
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Saki Tsutsumi
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Shota Togai
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Ryosuke Kobayashi
- Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Takuro Horii
- Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Izuho Hatada
- Viral Vector Core, Gunma University, Initiative for Advanced Research, Maebashi, Gunma 371-8511, Japan
- Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Hirokazu Hirai
- Department of Neurophysiology & Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
- Viral Vector Core, Gunma University, Initiative for Advanced Research, Maebashi, Gunma 371-8511, Japan
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Soto JS, Jami-Alahmadi Y, Wohlschlegel JA, Khakh BS. In vivo identification of astrocyte and neuron subproteomes by proximity-dependent biotinylation. Nat Protoc 2024; 19:896-927. [PMID: 38062165 DOI: 10.1038/s41596-023-00923-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/03/2023] [Indexed: 02/08/2024]
Abstract
The central nervous system (CNS) comprises diverse and morphologically complex cells. To understand the molecular basis of their physiology, it is crucial to assess proteins expressed within intact cells. Commonly used methods utilize cell dissociation and sorting to isolate specific cell types such as neurons and astrocytes, the major CNS cells. Proteins purified from isolated cells are identified by mass spectrometry-based proteomics. However, dissociation and cell-sorting methods lead to near total loss of cellular morphology, thereby losing proteins from key relevant subcompartments such as processes, end feet, dendrites and axons. Here we provide a systematic protocol for cell- and subcompartment-specific labeling and identification of proteins found within intact astrocytes and neurons in vivo. This protocol utilizes the proximity-dependent biotinylation system BioID2, selectively expressed in either astrocytes or neurons, to label proximal proteins in a cell-specific manner. BioID2 is targeted genetically to assess the subproteomes of subcellular compartments such as the plasma membrane and sites of cell-cell contacts. We describe in detail the expression methods (variable timing), stereotaxic surgeries for expression (1-2 d and then 3 weeks), in vivo protein labeling (7 d), protein isolation (2-3 d), protein identification methods (2-3 d) and data analysis (1 week). The protocol can be applied to any area of the CNS in mouse models of physiological processes and for disease-related research.
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Affiliation(s)
- Joselyn S Soto
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
| | - Yasaman Jami-Alahmadi
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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Li L, Vasan L, Kartono B, Clifford K, Attarpour A, Sharma R, Mandrozos M, Kim A, Zhao W, Belotserkovsky A, Verkuyl C, Schmitt-Ulms G. Advances in Recombinant Adeno-Associated Virus Vectors for Neurodegenerative Diseases. Biomedicines 2023; 11:2725. [PMID: 37893099 PMCID: PMC10603849 DOI: 10.3390/biomedicines11102725] [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: 09/08/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
Recombinant adeno-associated virus (rAAV) vectors are gene therapy delivery tools that offer a promising platform for the treatment of neurodegenerative diseases. Keeping up with developments in this fast-moving area of research is a challenge. This review was thus written with the intention to introduce this field of study to those who are new to it and direct others who are struggling to stay abreast of the literature towards notable recent studies. In ten sections, we briefly highlight early milestones within this field and its first clinical success stories. We showcase current clinical trials, which focus on gene replacement, gene augmentation, or gene suppression strategies. Next, we discuss ongoing efforts to improve the tropism of rAAV vectors for brain applications and introduce pre-clinical research directed toward harnessing rAAV vectors for gene editing applications. Subsequently, we present common genetic elements coded by the single-stranded DNA of rAAV vectors, their so-called payloads. Our focus is on recent advances that are bound to increase treatment efficacies. As needed, we included studies outside the neurodegenerative disease field that showcased improved pre-clinical designs of all-in-one rAAV vectors for gene editing applications. Finally, we discuss risks associated with off-target effects and inadvertent immunogenicity that these technologies harbor as well as the mitigation strategies available to date to make their application safer.
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Affiliation(s)
- Leyao Li
- Department of Biochemistry, University of Toronto, Medical Sciences Building, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
| | - Lakshmy Vasan
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Bryan Kartono
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Kevan Clifford
- Institute of Medical Science, University of Toronto, Medical Sciences Building, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
- Centre for Addiction and Mental Health (CAMH), 250 College St., Toronto, ON M5T 1R8, Canada
| | - Ahmadreza Attarpour
- Department of Medical Biophysics, University of Toronto, 101 College St., Toronto, ON M5G 1L7, Canada
| | - Raghav Sharma
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Matthew Mandrozos
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Ain Kim
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Wenda Zhao
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Ari Belotserkovsky
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Claire Verkuyl
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, ON M5T 0S8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
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Heffernan KS, Galvan A. Building and Characterization of an Affordable diOlistic Device for Single-Cell Labeling in Rodent and Non-Human Primate Brain Slices. Curr Protoc 2023; 3:e760. [PMID: 37068198 PMCID: PMC10347685 DOI: 10.1002/cpz1.760] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
In the brain, cell morphology often reflects function and thus provides a first glance into cell-specific changes in health and disease. Studying the morphology of individual cells, including neurons and glia, is essential to fully understand brain connectivity and changes in disease states. Many recent morphological studies of brain cells have relied on transgenic animals and viral vectors to label individual cells. However, transgenic animals are not always available, and in non-human primate (NHP) models, viral transduction poses several practical and financial challenges, limiting the number of researchers that can thoroughly investigate cell morphology in NHP or other non-transgenic animals. The diOlistic system for delivering fluorescent lipophilic dye-coated gold or tungsten particles into brain tissue has been used to label single cells, but the currently available systems are expensive, have limited applications, and are rare in laboratories. Investigations of cell morphology without transgenic or viral approaches rely on immunohistochemical markers that may not reveal structural detail, such as in astrocytes. To overcome these practical limitations to expand our understanding of cell morphology across species with an emphasis on astrocytes, we constructed a low-cost ballistic method to deliver dye-coated gold or tungsten particles into NHP and rodent brain slices. We have optimized the tissue processing parameters to achieve penetration of DiI-coated particles, allowing for the complete reconstruction of individual cells within a brain slice. While we report on astrocytes in rodent and NHP brain slices, this protocol can be adapted and implemented across species and tissue types to evaluate cell morphology. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Building the diOlistic device Basic Protocol 2: Preparation of dye "bullet" carriers Basic Protocol 3: Perfusion, brain sectioning, and diOlistic labeling Alternate Protocol: Immunohistochemical labeling of sections prior to diOlistic bombardment.
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Affiliation(s)
- Kate S Heffernan
- Division of Neuropharmacology and Neurological Disorders, Emory National Primate Research Center, Emory University, Atlanta, GA, USA
- Udall Center of Excellence for Parkinson’s Disease Research, Emory University, Atlanta, GA, USA
| | - Adriana Galvan
- Division of Neuropharmacology and Neurological Disorders, Emory National Primate Research Center, Emory University, Atlanta, GA, USA
- Udall Center of Excellence for Parkinson’s Disease Research, Emory University, Atlanta, GA, USA
- Department of Neurology, School of Medicine, Emory University, Atlanta, GA, USA
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Farrell K, McFadden T, Jarome TJ. Neuronal and astrocytic protein degradation are critical for fear memory formation. Learn Mem 2023; 30:70-73. [PMID: 36921984 PMCID: PMC10027238 DOI: 10.1101/lm.053716.122] [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: 11/22/2022] [Accepted: 02/21/2023] [Indexed: 03/17/2023]
Abstract
Strong evidence has implicated proteasome-mediated protein degradation in the memory consolidation process. However, due to the use of pharmacological approaches, the cell type specificity of this remains unknown. Here, we used neuron-specific and novel astrocyte-specific CRISPR-dCas9-KRAB-MECP2 plasmids to inhibit protein degradation in a cell type-specific manner in the amygdala of male rats. We found that while inhibition of neuronal, but not astrocytic, protein degradation impaired performance during the training session, both resulted in impaired contextual fear memory retention. Together, these data provide the first evidence of a cell type-specific role for protein degradation in the memory consolidation process.
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Affiliation(s)
- Kayla Farrell
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Taylor McFadden
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Timothy J Jarome
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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Looking to the stars for answers: Strategies for determining how astrocytes influence neuronal activity. Comput Struct Biotechnol J 2022; 20:4146-4156. [PMID: 36016711 PMCID: PMC9379862 DOI: 10.1016/j.csbj.2022.07.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/29/2022] [Accepted: 07/29/2022] [Indexed: 11/24/2022] Open
Abstract
Astrocytes are critical components of neural circuits positioned in close proximity to the synapse, allowing them to rapidly sense and respond to neuronal activity. One repeatedly observed biomarker of astroglial activation is an increase in intracellular Ca2+ levels. These astroglial Ca2+ signals are often observed spreading throughout various cellular compartments from perisynaptic astroglial processes, to major astrocytic branches and on to the soma or cell body. Here we review recent evidence demonstrating that astrocytic Ca2+ events are remarkably heterogeneous in both form and function, propagate through the astroglial syncytia, and are directly linked to the ability of astroglia to influence local neuronal activity. As many of the cellular functions of astroglia can be linked to intracellular Ca2+ signaling, and the diversity and heterogeneity of these events becomes more apparent, there is an increasing need for novel experimental strategies designed to better understand the how these signals evolve in parallel with neuronal activity. Here we review the recent advances that enable the characterization of both subcellular and population-wide astrocytic Ca2+ dynamics. Additionally, we also outline the experimental design required for simultaneous in vivo Ca2+ imaging in the context of neuronal or astroglial manipulation, highlighting new experimental strategies made possible by recent advances in viral vector, imaging, and quantification technologies. Through combined usage of these reagents and methodologies, we provide a conceptual framework to study how astrocytes functionally integrate into neural circuits and to what extent they influence and direct the synaptic activity underlying behavioral responses.
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