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Jenkins PM, Bender KJ. Axon initial segment structure and function in health and disease. Physiol Rev 2025; 105:765-801. [PMID: 39480263 DOI: 10.1152/physrev.00030.2024] [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: 08/01/2024] [Revised: 10/18/2024] [Accepted: 10/23/2024] [Indexed: 11/06/2024] Open
Abstract
At the simplest level, neurons are structured to integrate synaptic input and perform computational transforms on that input, converting it into an action potential (AP) code. This process, converting synaptic input into AP output, typically occurs in a specialized region of the axon termed the axon initial segment (AIS). The AIS, as its name implies, is often contained to the first section of axon abutted to the soma and is home to a dizzying array of ion channels, attendant scaffolding proteins, intracellular organelles, extracellular proteins, and, in some cases, synapses. The AIS serves multiple roles as the final arbiter for determining if inputs are sufficient to evoke APs, as a gatekeeper that physically separates the somatodendritic domain from the axon proper, and as a regulator of overall neuronal excitability, dynamically tuning its size to best suit the needs of parent neurons. These complex roles have received considerable attention from experimentalists and theoreticians alike. Here, we review recent advances in our understanding of the AIS and its role in neuronal integration and polarity in health and disease.
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Affiliation(s)
- Paul M Jenkins
- Departments of Pharmacology and Psychiatry, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Kevin J Bender
- Department of Neurology, Weill Institute for Neurosciences, University of California, San Francisco, California, United States
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2
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Sobierajski E, Czubay K, Schmidt MAR, Wiedenski S, Rettschlag S, Beemelmans C, Beemelmans C, Wahle P. Expression of synaptic proteins and development of dendritic spines in fetal and postnatal neocortex of the pig, the European wild boar Sus scrofa. Brain Struct Funct 2025; 230:38. [PMID: 39918645 PMCID: PMC11805786 DOI: 10.1007/s00429-025-02900-0] [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: 08/20/2024] [Accepted: 01/27/2025] [Indexed: 02/09/2025]
Abstract
Synapse formation is a critical step in neuronal development. Current knowledge is largely based on altricial rodents where synapse formation and maturation proceed largely postnatally. In precocially born mammals such as guinea pig presynapse and spine formation start well before birth. Here, we analysed the developmental expression of proteins associated with synapse formation and maturation together with the development of basal dendritic spines of pyramidal neurons of visual and somatosensory cortex of the pig, an emerging translational model for human neurodegenerative disorders. A total of 23 selected proteins was quantified with Western blots. Most were detectable from midgestation embryonal day (E) 65 onwards. About half reached the expression level seen at postnatal day (P) 90 pig already two weeks before birth (gestation 114 days) in somatosensory, albeit not yet in visual cortex. For instance, major molecular components of synaptic plasticity such as GluN2B, CamKIIα, α-actinin-2, synaptopodin and T286 phosphorylated CamKIIα were expressed at E100 in somatosensory cortex. Dendritic spine type quantification with DiI-labeled material revealed an increase of total dendritic protrusions from E70 onwards. The increase was steepest in somatosensory cortex which had, at E110, a proportion of mushroom spines equal to the proportion present at P90. Together, matching the ungulate life history, a rapid development of functional synaptic connectivity in prenatal somatosensory cortex serves the somatomotor abilities essentially required by the newborn nest-fledgling.
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Affiliation(s)
- Eric Sobierajski
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany.
| | - Katrin Czubay
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany
| | - Marc-André R Schmidt
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany
| | - Sebastian Wiedenski
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany
| | - Sarah Rettschlag
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany
| | - Christa Beemelmans
- Regionalverband Ruhr Grün, Forsthof Üfter Mark, Forsthausweg 306, Schermbeck, 46514, Germany
| | - Christoph Beemelmans
- Regionalverband Ruhr Grün, Forsthof Üfter Mark, Forsthausweg 306, Schermbeck, 46514, Germany
| | - Petra Wahle
- Faculty of Biology and Biotechnology, Developmental Neurobiology, Ruhr University Bochum, Bochum, 44870, Germany
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3
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Han Y, Hacker D, Donders BC, Parperis C, Thuenauer R, Leterrier C, Grünewald K, Mikhaylova M. Unveiling the cell biology of hippocampal neurons with dendritic axon origin. J Cell Biol 2025; 224:e202403141. [PMID: 39495320 PMCID: PMC11536041 DOI: 10.1083/jcb.202403141] [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: 03/26/2024] [Revised: 08/01/2024] [Accepted: 09/23/2024] [Indexed: 11/05/2024] Open
Abstract
In mammalian axon-carrying-dendrite (AcD) neurons, the axon emanates from a basal dendrite, instead of the soma, to create a privileged route for action potential generation at the axon initial segment (AIS). However, it is unclear how such unusual morphology is established and whether the structure and function of the AIS in AcD neurons are preserved. By using dissociated hippocampal cultures as a model, we show that the development of AcD morphology can occur prior to synaptogenesis and independently of the in vivo environment. A single precursor neurite first gives rise to the axon and then to the AcD. The AIS possesses a similar cytoskeletal architecture as the soma-derived AIS and similarly functions as a trafficking barrier to retain axon-specific molecular composition. However, it does not undergo homeostatic plasticity, contains lesser cisternal organelles, and receives fewer inhibitory inputs. Our findings reveal insights into AcD neuron biology and underscore AIS structural differences based on axon onset.
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Affiliation(s)
- Yuhao Han
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany
- AG “Neuronal Protein Transport”, Centre for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Structural Cell Biology of Viruses, Leibniz Institute of Virology (LIV), Hamburg, Germany
| | - Daniela Hacker
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany
| | | | | | - Roland Thuenauer
- Advanced Light and Fluorescence Microscopy (ALFM) Facility, Centre for Structural Systems Biology, Hamburg, Germany
- Technology Platform Light Microscopy, University of Hamburg, Hamburg, Germany
- Technology Platform Microscopy and Image Analysis (TP MIA), Leibniz Institute of Virology (LIV), Hamburg, Germany
| | | | - Kay Grünewald
- Centre for Structural Systems Biology, Hamburg, Germany
- Structural Cell Biology of Viruses, Leibniz Institute of Virology (LIV), Hamburg, Germany
- Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Marina Mikhaylova
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany
- AG “Neuronal Protein Transport”, Centre for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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4
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Sobierajski E, Czubay K, Beemelmans C, Beemelmans C, Meschkat M, Uhlenkamp D, Meyer G, Wahle P. Vascular Development of Fetal and Postnatal Neocortex of the Pig, the European Wild Boar Sus scrofa. J Comp Neurol 2024; 532:e70011. [PMID: 39660539 PMCID: PMC11632654 DOI: 10.1002/cne.70011] [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: 05/23/2024] [Revised: 10/14/2024] [Accepted: 10/21/2024] [Indexed: 12/12/2024]
Abstract
The development of the brain's vascular system is a predominantly prenatal process in mammalian species and is required for neurogenesis and further brain development. Our recent work on fetal pig has revealed that many neurodevelopmental processes start well before birth and proceed rapidly reaching near-mature status already around birth. Here, we analyzed the development of neocortical vasculature from embryonic day (E) 45 onward (gestation in pig lasts 114 days) using qualitative and quantitative image analyses and protein blots. In all cortical layers, vessel volume from total brain volume at E100 resembled that of a postnatal day (P) 30 piglet. Endothelial cells expressed the tight junction protein claudin-5 from E45 onward. GFAP+ and AQP4+ astrocytes, PDGFRβ+ pericytes, and α-SMA+ smooth muscle cells are detectable near vessels at E60 suggesting an early assembly of blood-brain barrier components. The vascular system in the visual cortex is advanced before birth with an almost mature pattern at E100. Findings were confirmed by blots that showed a steady increase of expression of tight junction and angiogenesis-related proteins (claudin-5, occludin, VE-cadherin, PECAM-1/CD31) from E65 onward until P90. The expression profile was similar in visual and somatosensory cortex. Together, we report a rapid maturation of the vascular system in pig cortex.
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Affiliation(s)
- Eric Sobierajski
- Department of Developmental Neurobiology, Faculty of Biology and BiotechnologyRuhr University BochumBochumGermany
| | - Katrin Czubay
- Department of Developmental Neurobiology, Faculty of Biology and BiotechnologyRuhr University BochumBochumGermany
| | | | | | | | | | - Gundela Meyer
- Department of Basic Medical Science, Faculty of MedicineUniversity of La LagunaSanta Cruz de TenerifeTenerifeSpain
| | - Petra Wahle
- Department of Developmental Neurobiology, Faculty of Biology and BiotechnologyRuhr University BochumBochumGermany
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5
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Celii B, Papadopoulos S, Ding Z, Fahey PG, Wang E, Papadopoulos C, Kunin A, Patel S, Bae JA, Bodor AL, Brittain D, Buchanan J, Bumbarger DJ, Castro MA, Cobos E, Dorkenwald S, Elabbady L, Halageri A, Jia Z, Jordan C, Kapner D, Kemnitz N, Kinn S, Lee K, Li K, Lu R, Macrina T, Mahalingam G, Mitchell E, Mondal SS, Mu S, Nehoran B, Popovych S, Schneider-Mizell CM, Silversmith W, Takeno M, Torres R, Turner NL, Wong W, Wu J, Yu SC, Yin W, Xenes D, Kitchell LM, Rivlin PK, Rose VA, Bishop CA, Wester B, Froudarakis E, Walker EY, Sinz FH, Seung HS, Collman F, da Costa NM, Reid RC, Pitkow X, Tolias AS, Reimer J. NEURD offers automated proofreading and feature extraction for connectomics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.14.532674. [PMID: 36993282 PMCID: PMC10055177 DOI: 10.1101/2023.03.14.532674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
We are now in the era of millimeter-scale electron microscopy (EM) volumes collected at nanometer resolution. Dense reconstruction of cellular compartments in these EM volumes has been enabled by recent advances in Machine Learning (ML). Automated segmentation methods produce exceptionally accurate reconstructions of cells, but post-hoc proofreading is still required to generate large connectomes free of merge and split errors. The elaborate 3-D meshes of neurons in these volumes contain detailed morphological information at multiple scales, from the diameter, shape, and branching patterns of axons and dendrites, down to the fine-scale structure of dendritic spines. However, extracting these features can require substantial effort to piece together existing tools into custom workflows. Building on existing open-source software for mesh manipulation, here we present "NEURD", a software package that decomposes meshed neurons into compact and extensively-annotated graph representations. With these feature-rich graphs, we automate a variety of tasks such as state of the art automated proofreading of merge errors, cell classification, spine detection, axon-dendritic proximities, and other annotations. These features enable many downstream analyses of neural morphology and connectivity, making these massive and complex datasets more accessible to neuroscience researchers focused on a variety of scientific questions.
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Benavides-Piccione R, Blazquez-Llorca L, Kastanauskaite A, Fernaud-Espinosa I, Tapia-González S, DeFelipe J. Key morphological features of human pyramidal neurons. Cereb Cortex 2024; 34:bhae180. [PMID: 38745556 PMCID: PMC11094408 DOI: 10.1093/cercor/bhae180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/01/2024] [Accepted: 04/18/2024] [Indexed: 05/16/2024] Open
Abstract
The basic building block of the cerebral cortex, the pyramidal cell, has been shown to be characterized by a markedly different dendritic structure among layers, cortical areas, and species. Functionally, differences in the structure of their dendrites and axons are critical in determining how neurons integrate information. However, within the human cortex, these neurons have not been quantified in detail. In the present work, we performed intracellular injections of Lucifer Yellow and 3D reconstructed over 200 pyramidal neurons, including apical and basal dendritic and local axonal arbors and dendritic spines, from human occipital primary visual area and associative temporal cortex. We found that human pyramidal neurons from temporal cortex were larger, displayed more complex apical and basal structural organization, and had more spines compared to those in primary sensory cortex. Moreover, these human neocortical neurons displayed specific shared and distinct characteristics in comparison to previously published human hippocampal pyramidal neurons. Additionally, we identified distinct morphological features in human neurons that set them apart from mouse neurons. Lastly, we observed certain consistent organizational patterns shared across species. This study emphasizes the existing diversity within pyramidal cell structures across different cortical areas and species, suggesting substantial species-specific variations in their computational properties.
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Affiliation(s)
- Ruth Benavides-Piccione
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Valderrebollo 5, Madrid 28031, Spain
| | - Lidia Blazquez-Llorca
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid 28223, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Valderrebollo 5, Madrid 28031, Spain
- Departamento de Tecnología Fotónica y Bioingeniería, ETSI Telecomunicación, Universidad Politécnica de Madrid, Madrid 28040, Spain
| | - Asta Kastanauskaite
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid 28223, Spain
| | - Isabel Fernaud-Espinosa
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, Madrid 28002, Spain
| | - Silvia Tapia-González
- Laboratorio de Neurofisiología Celular, Facultad de Medicina, Universidad San Pablo-CEU, CEU Universities, Madrid, Spain
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid 28223, Spain
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, Madrid 28002, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Valderrebollo 5, Madrid 28031, Spain
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7
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Safronov BV, Szucs P. Novel aspects of signal processing in lamina I. Neuropharmacology 2024; 247:109858. [PMID: 38286189 DOI: 10.1016/j.neuropharm.2024.109858] [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] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 01/31/2024]
Abstract
The most superficial layer of the spinal dorsal horn, lamina I, is a key element of the nociceptive processing system. It contains different types of projection neurons (PNs) and local-circuit neurons (LCNs) whose functional roles in the signal processing are poorly understood. This article reviews recent progress in elucidating novel anatomical features and physiological properties of lamina I PNs and LCNs revealed by whole-cell recordings in ex vivo spinal cord. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Boris V Safronov
- Neuronal Networks Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
| | - Peter Szucs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; HUN-REN-DE Neuroscience Research Group, Debrecen, Hungary
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8
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Vásquez CE, Knak Guerra KT, Renner J, Rasia-Filho AA. Morphological heterogeneity of neurons in the human central amygdaloid nucleus. J Neurosci Res 2024; 102:e25319. [PMID: 38629777 DOI: 10.1002/jnr.25319] [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: 11/26/2023] [Revised: 02/23/2024] [Accepted: 03/03/2024] [Indexed: 04/19/2024]
Abstract
The central amygdaloid nucleus (CeA) has an ancient phylogenetic development and functions relevant for animal survival. Local cells receive intrinsic amygdaloidal information that codes emotional stimuli of fear, integrate them, and send cortical and subcortical output projections that prompt rapid visceral and social behavior responses. We aimed to describe the morphology of the neurons that compose the human CeA (N = 8 adult men). Cells within CeA coronal borders were identified using the thionine staining and were further analyzed using the "single-section" Golgi method followed by open-source software procedures for two-dimensional and three-dimensional image reconstructions. Our results evidenced varied neuronal cell body features, number and thickness of primary shafts, dendritic branching patterns, and density and shape of dendritic spines. Based on these criteria, we propose the existence of 12 morphologically different spiny neurons in the human CeA and discuss the variability in the dendritic architecture within cellular types, including likely interneurons. Some dendritic shafts were long and straight, displayed few collaterals, and had planar radiation within the coronal neuropil volume. Most of the sampled neurons showed a few to moderate density of small stubby/wide spines. Long spines (thin and mushroom) were observed occasionally. These novel data address the synaptic processing and plasticity in the human CeA. Our morphological description can be combined with further transcriptomic, immunohistochemical, and electrophysiological/connectional approaches. It serves also to investigate how neurons are altered in neurological and psychiatric disorders with hindered emotional perception, in anxiety, following atrophy in schizophrenia, and along different stages of Alzheimer's disease.
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Affiliation(s)
- Carlos E Vásquez
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Kétlyn T Knak Guerra
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Josué Renner
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
| | - Alberto A Rasia-Filho
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
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9
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Stevens NA, Lankisch K, Draguhn A, Engelhardt M, Both M, Thome C. Increased Interhemispheric Connectivity of a Distinct Type of Hippocampal Pyramidal Cells. J Neurosci 2024; 44:e0440232023. [PMID: 38123997 PMCID: PMC10869156 DOI: 10.1523/jneurosci.0440-23.2023] [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: 02/28/2023] [Revised: 11/02/2023] [Accepted: 11/19/2023] [Indexed: 12/23/2023] Open
Abstract
Neurons typically generate action potentials at their axon initial segment based on the integration of synaptic inputs. In many neurons, the axon extends from the soma, equally weighting dendritic inputs. A notable exception is found in a subset of hippocampal pyramidal cells where the axon emerges from a basal dendrite. This structure allows these axon-carrying dendrites (AcDs) a privileged input route. We found that in male mice, such cells in the CA1 region receive stronger excitatory input from the contralateral CA3, compared with those with somatic axon origins. This is supported by a higher count of putative synapses from contralateral CA3 on the AcD. These findings, combined with prior observations of their distinct role in sharp-wave ripple firing, suggest a key role of this neuron subset in coordinating bi-hemispheric hippocampal activity during memory-centric oscillations.
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Affiliation(s)
- Nikolas Andreas Stevens
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Katja Lankisch
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Martin Both
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Christian Thome
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
- Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University Linz, 4020 Linz, Austria
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305
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10
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Gonda S, Riedel C, Reiner A, Köhler I, Wahle P. Axons of cortical basket cells originating from dendrites develop higher local complexity than axons emerging from basket cell somata. Development 2023; 150:dev202305. [PMID: 37902086 PMCID: PMC10690106 DOI: 10.1242/dev.202305] [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: 08/28/2023] [Accepted: 10/24/2023] [Indexed: 10/31/2023]
Abstract
Neuronal differentiation is regulated by neuronal activity. Here, we analyzed dendritic and axonal growth of Basket cells (BCs) and non-Basket cells (non-BCs) using sparse transfection of channelrhodopsin-YFP and repetitive optogenetic stimulation in slice cultures of rat visual cortex. Neocortical interneurons often display axon-carrying dendrites (AcDs). We found that the AcDs of BCs and non-BCs were, on average, the most complex dendrites. Further, the AcD configuration had an influence on BC axonal development. Axons originating from an AcD formed denser arborizations with more terminal endings within the dendritic field of the parent cell. Intriguingly, this occurred already in unstimulated BCs, and complexity was not increased further by optogenetic stimulation. However, optogenetic stimulation exerted a growth-promoting effect on axons emerging from BC somata. The axons of non-BCs neither responded to the AcD configuration nor to the optogenetic stimulation. The results suggest that the formation of locally dense BC plexuses is regulated by spontaneous activity. Moreover, in the AcD configuration, the AcD and the axon it carries mutually support each other's growth.
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Affiliation(s)
- Steffen Gonda
- Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany
| | - Christian Riedel
- Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany
| | - Andreas Reiner
- Cellular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany
| | - Ina Köhler
- Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany
| | - Petra Wahle
- Developmental Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany
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11
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Boal AM, McGrady NR, Chamling X, Kagitapalli BS, Zack DJ, Calkins DJ, Risner ML. Microfluidic Platforms Promote Polarization of Human-Derived Retinal Ganglion Cells That Model Axonopathy. Transl Vis Sci Technol 2023; 12:1. [PMID: 37010860 PMCID: PMC10080917 DOI: 10.1167/tvst.12.4.1] [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: 12/06/2022] [Accepted: 03/09/2023] [Indexed: 04/04/2023] Open
Abstract
Purpose Axons depend on long-range transport of proteins and organelles which increases susceptibility to metabolic stress in disease. The axon initial segment (AIS) is particularly vulnerable due to the high bioenergetic demand of action potential generation. Here, we prepared retinal ganglion cells derived from human embryonic stem cells (hRGCs) to probe how axonal stress alters AIS morphology. Methods hRGCs were cultured on coverslips or microfluidic platforms. We assayed AIS specification and morphology by immunolabeling against ankyrin G (ankG), an axon-specific protein, and postsynaptic density 95 (PSD-95), a dendrite-specific protein. Using microfluidic platforms that enable fluidic isolation, we added colchicine to the axon compartment to lesion axons. We verified axonopathy by measuring the anterograde axon transport of cholera toxin subunit B and immunolabeling against cleaved caspase 3 (CC3) and phosphorylated neurofilament H (SMI-34). We determined the influence of axon injury on AIS morphology by immunolabeling samples against ankG and measuring AIS distance from soma and length. Results Based on measurements of ankG and PSD-95 immunolabeling, microfluidic platforms promote the formation and separation of distinct somatic-dendritic versus axonal compartments in hRGCs compared to coverslip cultures. Chemical lesioning of axons by colchicine reduced hRGC anterograde axon transport, increased varicosity density, and enhanced expression of CC3 and SMI-34. Interestingly, we found that colchicine selectively affected hRGCs with axon-carrying dendrites by reducing AIS distance from somas and increasing length, thus suggesting reduced capacity to maintain excitability. Conclusions Thus, microfluidic platforms promote polarized hRGCs that enable modeling of axonopathy. Translational Relevance Microfluidic platforms may be used to assay compartmentalized degeneration that occurs during glaucoma.
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Affiliation(s)
- Andrew M. Boal
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Nolan R. McGrady
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xitiz Chamling
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bhanu S. Kagitapalli
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Donald J. Zack
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J. Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael L. Risner
- Vanderbilt Eye Institute, Department of Ophthalmology & Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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12
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Llach Pou M, Thiberge C, Van der Zwan M, Devi Govindan A, Pons S, Maskos U, Cloëz-Tayarani I. Developmental Changes of Human Neural Progenitor Cells Grafted into the Ventricular System and Prefrontal Cortex of Mouse Brain in Utero. Cells 2023; 12:1067. [PMID: 37048140 PMCID: PMC10093207 DOI: 10.3390/cells12071067] [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] [Received: 01/26/2023] [Revised: 03/06/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023] Open
Abstract
The transplantation of neural progenitors into a host brain represents a useful tool to evaluate the involvement of cell-autonomous processes and host local cues in the regulation of neuronal differentiation during the development of the mammalian brain. Human brain development starts at the embryonic stages, in utero, with unique properties at its neotenic stages. We analyzed the engraftment and differentiation of human neuronal progenitor cells (hNPCs) transplanted in utero into the mouse brain. The influence of the environment was studied by transplanting human NPCs within the lateral ventricles (LV), compared with the prefrontal cortex (PFC) of immunocompetent mice. We developed a semi-automated method to accurately quantify the number of cell bodies and the distribution of neuronal projections among the different mouse brain structures, at 1 and 3 months post-transplantation (MPT). Our data show that human NPCs can differentiate between immature "juvenile" neurons and more mature pyramidal cells in a reproducible manner. Depending on the injection site, LV vs. PFC, specific fetal local environments could modify the synaptogenesis processes while maintaining human neoteny. The use of immunocompetent mice as host species allows us to investigate further neuropathological conditions making use of all of the engineered mouse models already available.
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Affiliation(s)
- Maria Llach Pou
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Camille Thiberge
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Michiel Van der Zwan
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Annousha Devi Govindan
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
| | - Stéphanie Pons
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
| | - Uwe Maskos
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Isabelle Cloëz-Tayarani
- Institut Pasteur, Université Paris Cité, Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571 “Gènes, Synapses et Cognition”, 25 Rue du Docteur Roux, 75015 Paris, France
- Collège Doctoral, Sorbonne Université, 75005 Paris, France
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13
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Function follows form: how the structure of neurons determines cortical network activity : Comment on: Hodapp A, Kaiser ME, Thome C, Ding L, Rozov A, Klumpp M, Stevens N, Stingl M, Sackmann T, Lehmann N, Draguhn A, Burgalossi A, Engelhardt M, Both M (2022) Dendritic axon origin enables information gating by perisomatic inhibition in pyramidal neurons. Science 377:1448-1452. Pflugers Arch 2023; 475:285-287. [PMID: 36462030 PMCID: PMC9908714 DOI: 10.1007/s00424-022-02776-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/04/2022]
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14
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Abstract
Dendritic spine features in human neurons follow the up-to-date knowledge presented in the previous chapters of this book. Human dendrites are notable for their heterogeneity in branching patterns and spatial distribution. These data relate to circuits and specialized functions. Spines enhance neuronal connectivity, modulate and integrate synaptic inputs, and provide additional plastic functions to microcircuits and large-scale networks. Spines present a continuum of shapes and sizes, whose number and distribution along the dendritic length are diverse in neurons and different areas. Indeed, human neurons vary from aspiny or "relatively aspiny" cells to neurons covered with a high density of intermingled pleomorphic spines on very long dendrites. In this chapter, we discuss the phylogenetic and ontogenetic development of human spines and describe the heterogeneous features of human spiny neurons along the spinal cord, brainstem, cerebellum, thalamus, basal ganglia, amygdala, hippocampal regions, and neocortical areas. Three-dimensional reconstructions of Golgi-impregnated dendritic spines and data from fluorescence microscopy are reviewed with ultrastructural findings to address the complex possibilities for synaptic processing and integration in humans. Pathological changes are also presented, for example, in Alzheimer's disease and schizophrenia. Basic morphological data can be linked to current techniques, and perspectives in this research field include the characterization of spines in human neurons with specific transcriptome features, molecular classification of cellular diversity, and electrophysiological identification of coexisting subpopulations of cells. These data would enlighten how cellular attributes determine neuron type-specific connectivity and brain wiring for our diverse aptitudes and behavior.
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Affiliation(s)
- Josué Renner
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil
| | - Alberto A Rasia-Filho
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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15
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Hodapp A, Kaiser ME, Thome C, Ding L, Rozov A, Klumpp M, Stevens N, Stingl M, Sackmann T, Lehmann N, Draguhn A, Burgalossi A, Engelhardt M, Both M. Dendritic axon origin enables information gating by perisomatic inhibition in pyramidal neurons. Science 2022; 377:1448-1452. [PMID: 36137045 DOI: 10.1126/science.abj1861] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Information processing in neuronal networks involves the recruitment of selected neurons into coordinated spatiotemporal activity patterns. This sparse activation results from widespread synaptic inhibition in conjunction with neuron-specific synaptic excitation. We report the selective recruitment of hippocampal pyramidal cells into patterned network activity. During ripple oscillations in awake mice, spiking is much more likely in cells in which the axon originates from a basal dendrite rather than from the soma. High-resolution recordings in vitro and computer modeling indicate that these spikes are elicited by synaptic input to the axon-carrying dendrite and thus escape perisomatic inhibition. Pyramidal cells with somatic axon origin can be activated during ripple oscillations by blocking their somatic inhibition. The recruitment of neurons into active ensembles is thus determined by axonal morphological features.
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Affiliation(s)
- Alexander Hodapp
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Martin E Kaiser
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Christian Thome
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany.,Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University, Linz, Austria.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, USA
| | - Lingjun Ding
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.,Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany.,Graduate Training Centre of Neuroscience, IMPRS, Tübingen, Germany
| | - Andrei Rozov
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany.,Federal Center of Brain Research and Neurotechnologies, Moscow, Russian Federation.,OpenLab of Neurobiology, Kazan Federal University, Kazan, Russian Federation
| | - Matthias Klumpp
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Nikolas Stevens
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Moritz Stingl
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Tina Sackmann
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Nadja Lehmann
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Andrea Burgalossi
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.,Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University, Linz, Austria.,Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Martin Both
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
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16
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Rockland KS. Looking for the origins of axons. eLife 2022; 11:79839. [PMID: 35647816 PMCID: PMC9159749 DOI: 10.7554/elife.79839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pyramidal neurons with axons that exit from dendrites rather than the cell body itself are relatively common in non-primates, but rare in monkeys and humans.
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Affiliation(s)
- Kathleen S Rockland
- Department of Anatomy and Neurobiology School of Medicine, Boston University, Boston, United States
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