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Saraswathy VM, Zhou L, Mokalled MH. Single-cell analysis of innate spinal cord regeneration identifies intersecting modes of neuronal repair. bioRxiv 2023:2023.05.19.541505. [PMID: 37292638 PMCID: PMC10245778 DOI: 10.1101/2023.05.19.541505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Adult zebrafish have an innate ability to recover from severe spinal cord injury. Here, we report a comprehensive single nuclear RNA sequencing atlas that spans 6 weeks of regeneration. We identify cooperative roles for adult neurogenesis and neuronal plasticity during spinal cord repair. Neurogenesis of glutamatergic and GABAergic neurons restores the excitatory/inhibitory balance after injury. In addition, transient populations of injury-responsive neurons (iNeurons) show elevated plasticity between 1 and 3 weeks post-injury. Using cross-species transcriptomics and CRISPR/Cas9 mutagenesis, we found iNeurons are injury-surviving neurons that share transcriptional similarities with a rare population of spontaneously plastic mouse neurons. iNeurons are required for functional recovery and employ vesicular trafficking as an essential mechanism that underlies neuronal plasticity. This study provides a comprehensive resource of the cells and mechanisms that direct spinal cord regeneration and establishes zebrafish as a model of plasticity-driven neural repair.
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Feng R, Muraleedharan Saraswathy V, Mokalled MH, Cavalli V. Self-renewing macrophages in dorsal root ganglia contribute to promote nerve regeneration. Proc Natl Acad Sci U S A 2023; 120:e2215906120. [PMID: 36763532 PMCID: PMC9963351 DOI: 10.1073/pnas.2215906120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 01/07/2023] [Indexed: 02/11/2023] Open
Abstract
Sensory neurons located in dorsal root ganglia (DRG) convey sensory information from peripheral tissue to the brain. After peripheral nerve injury, sensory neurons switch to a regenerative state to enable axon regeneration and functional recovery. This process is not cell autonomous and requires glial and immune cells. Macrophages in the DRG (DRGMacs) accumulate in response to nerve injury, but their origin and function remain unclear. Here, we mapped the fate and response of DRGMacs to nerve injury using macrophage depletion, fate-mapping, and single-cell transcriptomics. We identified three subtypes of DRGMacs after nerve injury in addition to a small population of circulating bone-marrow-derived precursors. Self-renewing macrophages, which proliferate from local resident macrophages, represent the largest population of DRGMacs. The other two subtypes include microglia-like cells and macrophage-like satellite glial cells (SGCs) (Imoonglia). We show that self-renewing DRGMacs contribute to promote axon regeneration. Using single-cell transcriptomics data and CellChat to simulate intercellular communication, we reveal that macrophages express the neuroprotective and glioprotective ligand prosaposin and communicate with SGCs via the prosaposin receptor GPR37L1. These data highlight that DRGMacs have the capacity to self-renew, similarly to microglia in the Central nervous system (CNS) and contribute to promote axon regeneration. These data also reveal the heterogeneity of DRGMacs and their potential neuro- and glioprotective roles, which may inform future therapeutic approaches to treat nerve injury.
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Affiliation(s)
- Rui Feng
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO63110
| | - Vishnu Muraleedharan Saraswathy
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Mayssa H. Mokalled
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO63110
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO63110
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO63110
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Saraswathy VM, Zhou L, McAdow AR, Burris B, Dogra D, Reischauer S, Mokalled MH. Myostatin is a negative regulator of adult neurogenesis after spinal cord injury in zebrafish. Cell Rep 2022; 41:111705. [PMID: 36417881 PMCID: PMC9742758 DOI: 10.1016/j.celrep.2022.111705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 05/16/2022] [Accepted: 11/01/2022] [Indexed: 11/23/2022] Open
Abstract
Intrinsic and extrinsic inhibition of neuronal regeneration obstruct spinal cord (SC) repair in mammals. In contrast, adult zebrafish achieve functional recovery after complete SC transection. While studies of innate SC regeneration have focused on axon regrowth as a primary repair mechanism, how local adult neurogenesis affects functional recovery is unknown. Here, we uncover dynamic expression of zebrafish myostatin b (mstnb) in a niche of dorsal SC progenitors after injury. mstnb mutants show impaired functional recovery, normal glial and axonal bridging across the lesion, and an increase in the profiles of newborn neurons. Molecularly, neuron differentiation genes are upregulated, while the neural stem cell maintenance gene fgf1b is downregulated in mstnb mutants. Finally, we show that human fibroblast growth factor 1 (FGF1) treatment rescues the molecular and cellular phenotypes of mstnb mutants. These studies uncover unanticipated neurogenic functions for mstnb and establish the importance of local adult neurogenesis for innate SC repair.
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Affiliation(s)
- Vishnu Muraleedharan Saraswathy
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lili Zhou
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anthony R McAdow
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Brooke Burris
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Deepika Dogra
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany; Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Sven Reischauer
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany; Medical Clinic I, (Cardiology/Angiology) and Campus Kerckhoff, Justus Liebig University, Giessen, 35392 Giessen, Germany; The Cardio-Pulmonary Institute, Frankfurt, Germany
| | - Mayssa H Mokalled
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Saraswathy VM, Kurup AJ, Sharma P, Polès S, Poulain M, Fürthauer M. The E3 Ubiquitin Ligase Mindbomb1 controls planar cell polarity-dependent convergent extension movements during zebrafish gastrulation. eLife 2022; 11:71928. [PMID: 35142609 PMCID: PMC8937233 DOI: 10.7554/elife.71928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 02/09/2022] [Indexed: 11/13/2022] Open
Abstract
Vertebrate Delta/Notch signaling involves multiple ligands, receptors and transcription factors. Delta endocytosis - a critical event for Notch activation - is however essentially controlled by the E3 Ubiquitin ligase Mindbomb1 (Mib1). Mib1 inactivation is therefore often used to inhibit Notch signaling. However, recent findings indicate that Mib1 function extends beyond the Notch pathway. We report a novel Notch-independent role of Mib1 in zebrafish gastrulation. mib1 null mutants and morphants display impaired Convergence Extension (CE) movements. Comparison of different mib1 mutants and functional rescue experiments indicate that Mib1 controls CE independently of Notch. Mib1-dependent CE defects can be rescued using the Planar Cell Polarity (PCP) downstream mediator RhoA, or enhanced through knock-down of the PCP ligand Wnt5b. Mib1 regulates CE through its RING Finger domains that have been implicated in substrate ubiquitination, suggesting that Mib1 may control PCP protein trafficking. Accordingly, we show that Mib1 controls the endocytosis of the PCP component Ryk and that Ryk internalization is required for CE. Numerous morphogenetic processes involve both Notch and PCP signaling. Our observation that during zebrafish gastrulation Mib1 exerts a Notch-independent control of PCP-dependent CE movements suggest that Mib1 loss of function phenotypes should be cautiously interpreted depending on the biological context.
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Affiliation(s)
| | | | | | - Sophie Polès
- Université Côte d'Azur, CNRS, Inserm, iBV, Nice, France
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Klatt Shaw D, Saraswathy VM, Zhou L, McAdow AR, Burris B, Butka E, Morris SA, Dietmann S, Mokalled MH. Localized EMT reprograms glial progenitors to promote spinal cord repair. Dev Cell 2021; 56:613-626.e7. [PMID: 33609461 DOI: 10.1016/j.devcel.2021.01.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/17/2020] [Accepted: 01/22/2021] [Indexed: 02/06/2023]
Abstract
Anti-regenerative scarring obstructs spinal cord repair in mammals and presents a major hurdle for regenerative medicine. In contrast, adult zebrafish possess specialized glial cells that spontaneously repair spinal cord injuries by forming a pro-regenerative bridge across the severed tissue. To identify the mechanisms that regulate differential regenerative capacity between mammals and zebrafish, we first defined the molecular identity of zebrafish bridging glia and then performed cross-species comparisons with mammalian glia. Our transcriptomics show that pro-regenerative zebrafish glia activate an epithelial-to-mesenchymal transition (EMT) gene program and that EMT gene expression is a major factor distinguishing mammalian and zebrafish glia. Functionally, we found that localized niches of glial progenitors undergo EMT after spinal cord injury in zebrafish and, using large-scale CRISPR-Cas9 mutagenesis, we identified the gene regulatory network that activates EMT and drives functional regeneration. Thus, non-regenerative mammalian glia lack an essential EMT-driving gene regulatory network that reprograms pro-regenerative zebrafish glia after injury.
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Affiliation(s)
- Dana Klatt Shaw
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Lili Zhou
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anthony R McAdow
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Brooke Burris
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Emily Butka
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Samantha A Morris
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sabine Dietmann
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Mayssa H Mokalled
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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