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Awad M, Sayed RKA, Mohammadin D, Hussein MM, Mokhtar DM. Structural characteristics and regenerative potential: Insights from the molly fish spinal cord. Microsc Res Tech 2024. [PMID: 38923674 DOI: 10.1002/jemt.24633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 05/16/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024]
Abstract
Unlike mammals, species such as fish and amphibians can regenerate damaged spinal cords, offering insights into potential therapeutic targets. This study investigates the structural features of the molly fish spinal cord through light and electron microscopy. The most notable characteristic was the presence of Mauthner cells (M-cells), which exhibited large cell bodies and processes, as well as synaptic connections with astrocytes. These astrocytic connections contained synaptic vesicles, suggesting electrical transmission at the M-cell endings. Astrocytes, which were labeled with glial fibrillary acidic protein (GFAP), contained cytoplasmic glycogen granules, potentially serving as an emergency fuel source. Two types of oligodendrocytes were identified: a small, dark cell and a larger, lighter cell, both of which reacted strongly with oligodendrocyte transcription factor 2 (Olig2). The dark oligodendrocyte resembled human oligodendrocyte precursors, while the light oligodendrocyte was similar to mature human oligodendrocytes. Additionally, proliferative neurons in the substantia grisea centralis expressed myostatin, Nrf2, and Sox9. Collectively, these findings suggest that the molly fish spinal cord has advanced structural features conducive to spinal cord regeneration and could serve as an excellent model for studying central nervous system regeneration. Further studies on the functional aspects of the molly fish spinal cord are recommended. RESEARCH HIGHLIGHTS: Mauthner cells (M-cell), with their typical large cell body and processes, were the most characteristic feature in Molly fish spinal cord, where it presented synaptic connections with astrocytes and their ends contained synaptic vesicles indicating an electrical transmission in the M-cells endings. Two types of oligodendrocytes could be recognized; both reacted intensely with Oligodendrocyte transcription factor 2 (Olig2). The proliferative neurons of the substantia grisea centralis expressed myostatin, Nrf2, and Sox9. The findings of this study suggest that molly fish possess highly developed structural features conducive to spinal cord regeneration. Consequently, they could be deemed an exemplary model for investigating central nervous system regeneration.
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Affiliation(s)
- Mahmoud Awad
- Department of Histology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
| | - Ramy K A Sayed
- Department of Histology, Faculty of Veterinary Medicine, Sohag University, Sohag, Egypt
| | - Dalia Mohammadin
- Department of Histology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
| | - Marwa M Hussein
- Department of Cell and Tissues, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
| | - Doaa M Mokhtar
- Department of Cell and Tissues, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
- Department of Histology and Anatomy, School of Veterinary Medicine, Badr University in Assiut, Assiut, Egypt
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Starikov L, Ghinia-Tegla M, Kottmann AH. Lateral Motor Column specific expression of Sonic Hedgehog contributes to maintenance and scaling of pMN progenitor cell populations during oligodendrogenesis. RESEARCH SQUARE 2024:rs.3.rs-4249282. [PMID: 38798533 PMCID: PMC11118686 DOI: 10.21203/rs.3.rs-4249282/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Motor neurons (MNs) and oligodendrocyte precursor cells (OPCs) emerge sequentially from the pMN precursor domain during spinal cord development. MNs diversify into muscle specific subtypes and settle in stereotypic locations in the ventral horns. In contrast, OPCs are mobile and appear to evenly populate the parenchyma. Whether earlier born MNs influence OPC production is controversial. We found that Sonic Hedgehog signaling emanating from nascent MNs of the lateral motor column is critical for maintaining a larger and more yielding pMN domain at limb levels compared to trunk levels during OPC production. Reduced Shh signaling resulted in unrecoverable diminishment of pMN domain based OPC production leaving the spinal cord impoverished of OPC. Our results suggest that production of OPC at limb levels is contingent on completion of MN production.
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Affiliation(s)
- Lev Starikov
- City University of New York School of Medicine (CSOM), Dept. of Molecular, Cellular and Biomedical Sciences, New York City, NY 10031, USA
- City University of New York Graduate Center, Molecular, Cellular, and Developmental Biology Subprogram, New York City, NY 10016, USA
| | | | - Andreas H. Kottmann
- City University of New York School of Medicine (CSOM), Dept. of Molecular, Cellular and Biomedical Sciences, New York City, NY 10031, USA
- City University of New York Graduate Center, Molecular, Cellular, and Developmental Biology Subprogram, New York City, NY 10016, USA
- City University of New York Graduate Center, Neuroscience Subprogram, New York City, NY 10016, USA3
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3
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Walker MF, Zhang J, Steiner W, Ku PI, Zhu JF, Michaelson Z, Yen YC, Lee A, Long AB, Casey MJ, Poddar A, Nelson IB, Arveseth CD, Nagel F, Clough R, LaPotin S, Kwan KM, Schulz S, Stewart RA, Tesmer JJG, Caspary T, Subramanian R, Ge X, Myers BR. GRK2 Kinases in the Primary Cilium Initiate SMOOTHENED-PKA Signaling in the Hedgehog Cascade. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.10.540226. [PMID: 37214942 PMCID: PMC10197709 DOI: 10.1101/2023.05.10.540226] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
During Hedgehog (Hh) signal transduction in development and disease, the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO) communicates with GLI transcription factors by binding the protein kinase A catalytic subunit (PKA-C) and physically blocking its enzymatic activity. Here we show that GPCR kinase 2 (GRK2) orchestrates this process during endogenous Hh pathway activation in the vertebrate primary cilium. Upon SMO activation, GRK2 rapidly relocalizes from the ciliary base to the shaft, triggering SMO phosphorylation and PKA-C interaction. Reconstitution studies reveal that GRK2 phosphorylation enables active SMO to bind PKA-C directly. Lastly, the SMO-GRK2-PKA pathway underlies Hh signal transduction in a range of cellular and in vivo models. Thus, GRK2 phosphorylation of ciliary SMO, and the ensuing PKA-C binding and inactivation, are critical initiating events for the intracellular steps in Hh signaling. More broadly, our study suggests an expanded role for GRKs in enabling direct GPCR interactions with diverse intracellular effectors.
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Lencer E, Rains A, Binne E, Prekeris R, Artinger KB. Mutations in cdon and boc affect trunk neural crest cell migration and slow-twitch muscle development in zebrafish. Development 2023; 150:dev201304. [PMID: 37390228 PMCID: PMC10357035 DOI: 10.1242/dev.201304] [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: 10/04/2022] [Accepted: 06/22/2023] [Indexed: 07/02/2023]
Abstract
The transmembrane proteins cdon and boc are implicated in regulating hedgehog signaling during vertebrate development. Recent work showing roles for these genes in axon guidance and neural crest cell migration suggest that cdon and boc may play additional functions in regulating directed cell movements. We use newly generated and existing mutants to investigate a role for cdon and boc in zebrafish neural crest cell migration. We find that single mutant embryos exhibit normal neural crest phenotypes, but that neural crest migration is strikingly disrupted in double cdon;boc mutant embryos. We further show that this migration phenotype is associated with defects in the differentiation of slow-twitch muscle cells, and the loss of a Col1a1a-containing extracellular matrix, suggesting that neural crest defects may be a secondary consequence to defects in mesoderm development. Combined, our data add to a growing literature showing that cdon and boc act synergistically to promote hedgehog signaling during vertebrate development, and suggest that the zebrafish can be used to study the function of hedgehog receptor paralogs.
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Affiliation(s)
- Ezra Lencer
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Addison Rains
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Cell Biology, Stem Cells and Development Graduate Program, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Erin Binne
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Kristin B. Artinger
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, USA
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Dermitzakis I, Manthou ME, Meditskou S, Miliaras D, Kesidou E, Boziki M, Petratos S, Grigoriadis N, Theotokis P. Developmental Cues and Molecular Drivers in Myelinogenesis: Revisiting Early Life to Re-Evaluate the Integrity of CNS Myelin. Curr Issues Mol Biol 2022; 44:3208-3237. [PMID: 35877446 PMCID: PMC9324160 DOI: 10.3390/cimb44070222] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/14/2022] [Accepted: 07/17/2022] [Indexed: 02/07/2023] Open
Abstract
The mammalian central nervous system (CNS) coordinates its communication through saltatory conduction, facilitated by myelin-forming oligodendrocytes (OLs). Despite the fact that neurogenesis from stem cell niches has caught the majority of attention in recent years, oligodendrogenesis and, more specifically, the molecular underpinnings behind OL-dependent myelinogenesis, remain largely unknown. In this comprehensive review, we determine the developmental cues and molecular drivers which regulate normal myelination both at the prenatal and postnatal periods. We have indexed the individual stages of myelinogenesis sequentially; from the initiation of oligodendrocyte precursor cells, including migration and proliferation, to first contact with the axon that enlists positive and negative regulators for myelination, until the ultimate maintenance of the axon ensheathment and myelin growth. Here, we highlight multiple developmental pathways that are key to successful myelin formation and define the molecular pathways that can potentially be targets for pharmacological interventions in a variety of neurological disorders that exhibit demyelination.
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Affiliation(s)
- Iasonas Dermitzakis
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (I.D.); (M.E.M.); (S.M.); (D.M.)
| | - Maria Eleni Manthou
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (I.D.); (M.E.M.); (S.M.); (D.M.)
| | - Soultana Meditskou
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (I.D.); (M.E.M.); (S.M.); (D.M.)
| | - Dimosthenis Miliaras
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (I.D.); (M.E.M.); (S.M.); (D.M.)
| | - Evangelia Kesidou
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece; (E.K.); (M.B.); (N.G.)
| | - Marina Boziki
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece; (E.K.); (M.B.); (N.G.)
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC 3004, Australia;
| | - Nikolaos Grigoriadis
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece; (E.K.); (M.B.); (N.G.)
| | - Paschalis Theotokis
- Department of Histology-Embryology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (I.D.); (M.E.M.); (S.M.); (D.M.)
- Laboratory of Experimental Neurology and Neuroimmunology, Second Department of Neurology, AHEPA University Hospital, 54621 Thessaloniki, Greece; (E.K.); (M.B.); (N.G.)
- Correspondence:
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Reciprocal Regulation of Shh Trafficking and H2O2 Levels via a Noncanonical BOC-Rac1 Pathway. Antioxidants (Basel) 2022; 11:antiox11040718. [PMID: 35453403 PMCID: PMC9025708 DOI: 10.3390/antiox11040718] [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: 02/14/2022] [Revised: 03/25/2022] [Accepted: 04/03/2022] [Indexed: 11/21/2022] Open
Abstract
Among molecules that bridge environment, cell metabolism, and cell signaling, hydrogen peroxide (H2O2) recently appeared as an emerging but central player. Its level depends on cell metabolism and environment and was recently shown to play key roles during embryogenesis, contrasting with its long-established role in disease progression. We decided to explore whether the secreted morphogen Sonic hedgehog (Shh), known to be essential in a variety of biological processes ranging from embryonic development to adult tissue homeostasis and cancers, was part of these interactions. Here, we report that H2O2 levels control key steps of Shh delivery in cell culture: increased levels reduce primary secretion, stimulate endocytosis and accelerate delivery to recipient cells; in addition, physiological in vivo modulation of H2O2 levels changes Shh distribution and tissue patterning. Moreover, a feedback loop exists in which Shh trafficking controls H2O2 synthesis via a non-canonical BOC-Rac1 pathway, leading to cytoneme growth. Our findings reveal that Shh directly impacts its own distribution, thus providing a molecular explanation for the robustness of morphogenesis to both environmental insults and individual variability.
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Stenzel A, Mumme-Monheit A, Sucharov J, Walker M, Mitchell JM, Appel B, Nichols JT. Distinct and redundant roles for zebrafish her genes during mineralization and craniofacial patterning. Front Endocrinol (Lausanne) 2022; 13:1033843. [PMID: 36578958 PMCID: PMC9791542 DOI: 10.3389/fendo.2022.1033843] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
The Notch pathway is a cell-cell communication system which is critical for many developmental processes, including craniofacial development. Notch receptor activation induces expression of several well-known canonical targets including those encoded by the hes and her genes in mammals and zebrafish, respectively. The function of these genes, individually and in combination, during craniofacial development is not well understood. Here, we used zebrafish genetics to investigate her9 and her6 gene function during craniofacial development. We found that her9 is required for osteoblasts to efficiently mineralize bone, while cartilage is largely unaffected. Strikingly, gene expression studies in her9 mutants indicate that although progenitor cells differentiate into osteoblasts at the appropriate time and place, they fail to efficiently lay down mineralized matrix. This mineralization role of her9 is likely independent of Notch activation. In contrast, her9 also functions redundantly with her6 downstream of Jagged1b-induced Notch activation during dorsoventral craniofacial patterning. These studies disentangle distinct and redundant her gene functions during craniofacial development, including an unexpected, Notch independent, requirement during bone mineralization.
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Affiliation(s)
- Amanda Stenzel
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Abigail Mumme-Monheit
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Juliana Sucharov
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Macie Walker
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Jennyfer M. Mitchell
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Bruce Appel
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - James T. Nichols
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
- *Correspondence: James T. Nichols,
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Neely SA, Lyons DA. Insights Into Central Nervous System Glial Cell Formation and Function From Zebrafish. Front Cell Dev Biol 2021; 9:754606. [PMID: 34912801 PMCID: PMC8666443 DOI: 10.3389/fcell.2021.754606] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/05/2021] [Indexed: 12/23/2022] Open
Abstract
The term glia describes a heterogenous collection of distinct cell types that make up a large proportion of our nervous system. Although once considered the glue of the nervous system, the study of glial cells has evolved significantly in recent years, with a large body of literature now highlighting their complex and diverse roles in development and throughout life. This progress is due, in part, to advances in animal models in which the molecular and cellular mechanisms of glial cell development and function as well as neuron-glial cell interactions can be directly studied in vivo in real time, in intact neural circuits. In this review we highlight the instrumental role that zebrafish have played as a vertebrate model system for the study of glial cells, and discuss how the experimental advantages of the zebrafish lend themselves to investigate glial cell interactions and diversity. We focus in particular on recent studies that have provided insight into the formation and function of the major glial cell types in the central nervous system in zebrafish.
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Affiliation(s)
- Sarah A. Neely
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - David A. Lyons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Doll CA, Scott K, Appel B. Fmrp regulates oligodendrocyte lineage cell specification and differentiation. Glia 2021; 69:2349-2361. [PMID: 34110049 DOI: 10.1002/glia.24041] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 11/10/2022]
Abstract
Neurodevelopment requires the precise integration of a wide variety of neuronal and glial cell types. During early embryonic development, motor neurons and then oligodendrocyte precursor cells (OPCs) are specified from neural progenitors residing in the periventricular pMN progenitor domain of the spinal cord. Following gliogenesis, OPCs can differentiate as oligodendrocytes (OLs)-the myelinating glial cells of the central nervous system-or remain as OPCs. To generate unique cell types capable of highly divergent functions, these specification and differentiation events require specialized gene expression programs. RNA binding proteins (RBPs) regulate mRNA localization and translation in the developing nervous system and are linked to many neurodevelopmental disorders. One example is Fragile X syndrome (FXS), caused by the loss of the RBP fragile X mental retardation protein (FMRP). Importantly, infants with FXS have reduced white matter and we previously showed that zebrafish Fmrp is autonomously required in OLs to promote myelin sheath growth. We now find that Fmrp regulates cell specification in pMN progenitor cells such that fmr1 mutant zebrafish generate fewer motor neurons and excess OPCs. Fmrp subsequently promotes differentiation of OPCs, leading to fewer differentiating OLs in the developing spinal cord of fmr1 larvae. Although the early patterning of spinal progenitor domains appears largely normal in fmr1 mutants during early embryogenesis, Shh signaling is greatly diminished. Taken together, these results suggest cell stage-specific requirements for Fmrp in the specification and differentiation of oligodendrocyte lineage cells.
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Affiliation(s)
- Caleb A Doll
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Kayt Scott
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Bruce Appel
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado, USA
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