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Agha MA, Kishore S, McLean DL. Cell-type-specific origins of locomotor rhythmicity at different speeds in larval zebrafish. eLife 2024; 13:RP94349. [PMID: 39287613 PMCID: PMC11407768 DOI: 10.7554/elife.94349] [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: 09/19/2024] Open
Abstract
Different speeds of locomotion require heterogeneous spinal populations, but a common mode of rhythm generation is presumed to exist. Here, we explore the cellular versus synaptic origins of spinal rhythmicity at different speeds by performing electrophysiological recordings from premotor excitatory interneurons in larval zebrafish. Chx10-labeled V2a neurons are divided into at least two morphological subtypes proposed to play distinct roles in timing and intensity control. Consistent with distinct rhythm generating and output patterning functions within the spinal V2a population, we find that descending subtypes are recruited exclusively at slow or fast speeds and exhibit intrinsic cellular properties suitable for rhythmogenesis at those speeds, while bifurcating subtypes are recruited more reliably at all speeds and lack appropriate rhythmogenic cellular properties. Unexpectedly, however, phasic firing patterns during locomotion in rhythmogenic and non-rhythmogenic V2a neurons alike are best explained by distinct modes of synaptic inhibition linked to cell type and speed. At fast speeds reciprocal inhibition in descending V2a neurons supports phasic firing, while recurrent inhibition in bifurcating V2a neurons helps pattern motor output. In contrast, at slow speeds recurrent inhibition in descending V2a neurons supports phasic firing, while bifurcating V2a neurons rely on reciprocal inhibition alone to pattern output. Our findings suggest cell-type-specific, not common, modes of rhythmogenesis generate and coordinate different speeds of locomotion.
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Affiliation(s)
- Moneeza A Agha
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Interdisciplinary Biological Sciences Graduate Program, Northwestern UniversityEvanstonUnited States
| | - Sandeep Kishore
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
| | - David L McLean
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Interdisciplinary Biological Sciences Graduate Program, Northwestern UniversityEvanstonUnited States
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2
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Rots D, Choufani S, Faundes V, Dingemans AJM, Joss S, Foulds N, Jones EA, Stewart S, Vasudevan P, Dabir T, Park SM, Jewell R, Brown N, Pais L, Jacquemont S, Jizi K, Ravenswaaij-Arts CMAV, Kroes HY, Stumpel CTRM, Ockeloen CW, Diets IJ, Nizon M, Vincent M, Cogné B, Besnard T, Kambouris M, Anderson E, Zackai EH, McDougall C, Donoghue S, O'Donnell-Luria A, Valivullah Z, O'Leary M, Srivastava S, Byers H, Leslie N, Mazzola S, Tiller GE, Vera M, Shen JJ, Boles R, Jain V, Brischoux-Boucher E, Kinning E, Simpson BN, Giltay JC, Harris J, Keren B, Guimier A, Marijon P, Vries BBAD, Motter CS, Mendelsohn BA, Coffino S, Gerkes EH, Afenjar A, Visconti P, Bacchelli E, Maestrini E, Delahaye-Duriez A, Gooch C, Hendriks Y, Adams H, Thauvin-Robinet C, Josephi-Taylor S, Bertoli M, Parker MJ, Rutten JW, Caluseriu O, Vernon HJ, Kaziyev J, Zhu J, Kremen J, Frazier Z, Osika H, Breault D, Nair S, Lewis SME, Ceroni F, Viggiano M, Posar A, Brittain H, Giovanna T, Giulia G, Quteineh L, Ha-Vinh Leuchter R, Zonneveld-Huijssoon E, Mellado C, Marey I, Coudert A, Aracena Alvarez MI, Kennis MGP, Bouman A, Roifman M, Amorós Rodríguez MI, Ortigoza-Escobar JD, Vernimmen V, Sinnema M, Pfundt R, Brunner HG, Vissers LELM, Kleefstra T, Weksberg R, Banka S. Pathogenic variants in KMT2C result in a neurodevelopmental disorder distinct from Kleefstra and Kabuki syndromes. Am J Hum Genet 2024; 111:1626-1642. [PMID: 39013459 PMCID: PMC11339626 DOI: 10.1016/j.ajhg.2024.06.009] [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: 03/18/2024] [Revised: 06/08/2024] [Accepted: 06/19/2024] [Indexed: 07/18/2024] Open
Abstract
Trithorax-related H3K4 methyltransferases, KMT2C and KMT2D, are critical epigenetic modifiers. Haploinsufficiency of KMT2C was only recently recognized as a cause of neurodevelopmental disorder (NDD), so the clinical and molecular spectrums of the KMT2C-related NDD (now designated as Kleefstra syndrome 2) are largely unknown. We ascertained 98 individuals with rare KMT2C variants, including 75 with protein-truncating variants (PTVs). Notably, ∼15% of KMT2C PTVs were inherited. Although the most highly expressed KMT2C transcript consists of only the last four exons, pathogenic PTVs were found in almost all the exons of this large gene. KMT2C variant interpretation can be challenging due to segmental duplications and clonal hematopoesis-induced artifacts. Using samples from 27 affected individuals, divided into discovery and validation cohorts, we generated a moderate strength disorder-specific KMT2C DNA methylation (DNAm) signature and demonstrate its utility in classifying non-truncating variants. Based on 81 individuals with pathogenic/likely pathogenic variants, we demonstrate that the KMT2C-related NDD is characterized by developmental delay, intellectual disability, behavioral and psychiatric problems, hypotonia, seizures, short stature, and other comorbidities. The facial module of PhenoScore, applied to photographs of 34 affected individuals, reveals that the KMT2C-related facial gestalt is significantly different from the general NDD population. Finally, using PhenoScore and DNAm signatures, we demonstrate that the KMT2C-related NDD is clinically and epigenetically distinct from Kleefstra and Kabuki syndromes. Overall, we define the clinical features, molecular spectrum, and DNAm signature of the KMT2C-related NDD and demonstrate they are distinct from Kleefstra and Kabuki syndromes highlighting the need to rename this condition.
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Affiliation(s)
- Dmitrijs Rots
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Clinical Genetics, Erasmus MC, Rotterdam, the Netherlands; Genetics Laboratory, Children's Clinical University Hospital, Riga, Latvia
| | - Sanaa Choufani
- Genetics and Genome Biology Program, Research Institute, the Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Victor Faundes
- Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnología de Los Alimentos (INTA), Universidad de Chile, Santiago, Chile; Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | | | - Shelagh Joss
- West of Scotland Centre for Genomic Medicine, Queen Elizabeth University Hospital, Glasgow, UK
| | - Nicola Foulds
- Wessex Clinical Genetics Services, University Hospital Southampton NHS Foundation Trust, Southampton SO16 5YA, UK
| | - Elizabeth A Jones
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK; Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Sarah Stewart
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Pradeep Vasudevan
- Department of Clinical Genetics, University Hospitals of Leicester, Leicester Royal Infirmary, Leicester LE1 7RH, UK
| | - Tabib Dabir
- Northern Ireland Regional Genetics Centre, Belfast City Hospital, Belfast, UK
| | - Soo-Mi Park
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Rosalyn Jewell
- Yorkshire Regional Genetics Service, Chapel Allerton Hospital, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Natasha Brown
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, Royal Children's Hospital, The University of Melbourne, Melbourne, VIC, Australia
| | - Lynn Pais
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Khadijé Jizi
- Service de Génétique Médicale, CHU Ste-Justine, Montréal, QC, Canada
| | | | - Hester Y Kroes
- Division Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Constance T R M Stumpel
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, the Netherlands; GROW-School for Oncology and Reproduction, Maastricht, the Netherlands
| | - Charlotte W Ockeloen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Illja J Diets
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Mathilde Nizon
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Marie Vincent
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Benjamin Cogné
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Thomas Besnard
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Marios Kambouris
- Division of Genetics, Department of Pathology and Laboratory Medicine Department, Sidra Medicine, Doha, Qatar
| | - Emily Anderson
- Liverpool Centre for Genomic Medicine, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Elaine H Zackai
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Carey McDougall
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sarah Donoghue
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Anne O'Donnell-Luria
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Zaheer Valivullah
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Melanie O'Leary
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | | | - Heather Byers
- Department of Pediatrics, Stanford University, Stanford, CA, USA
| | - Nancy Leslie
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Sarah Mazzola
- Center for Personalized Genetic Healthcare, Cleveland Clinic, Cleveland, OH, USA
| | - George E Tiller
- Department of Genetics, Kaiser Permanente, Los Angeles, CA, USA
| | - Moin Vera
- Department of Genetics, Kaiser Permanente, Los Angeles, CA, USA
| | - Joseph J Shen
- Division of Genetics, Department of Pediatrics, UCSF Fresno, Fresno, CA, USA; Division of Genomic Medicine, Department of Pediatrics, University of California Davis, Sacramento, CA, USA
| | | | - Vani Jain
- All Wales Medical Genomics Service, Wales Genomic Health Centre, Cardiff Edge Business Park, Longwood Drive, Whitchurch, Cardiff CF14 7YU, UK
| | | | - Esther Kinning
- Clinical Genetics, Birmingham Women's and Children's, Birmingham, UK
| | - Brittany N Simpson
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
| | - Jacques C Giltay
- Division Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Jacqueline Harris
- Kennedy Krieger Institute, Baltimore, MD, USA; Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Boris Keren
- Department of Genetics, APHP Sorbonne University, Paris, France
| | - Anne Guimier
- Service de Médecine Genomique des Maladies Rares, CRMR Anomalies Du Développement, Hôpital Necker-Enfants Malades, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - Pierre Marijon
- Laboratoire de Biologie Médicale Multisites Seqoia FMG2025, 75014 Paris, France
| | - Bert B A de Vries
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | | | - Samantha Coffino
- Department of Pediatric Neurology, Kaiser Permanente, Oakland, CA, USA
| | - Erica H Gerkes
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Alexandra Afenjar
- APHP Sorbonne Université, Centre de Référence Malformations et Maladies Congénitales Du Cervelet et Déficiences Intellectuelles de Causes Rares, Département de Génétique et Embryologie Médicale, Hôpital Trousseau, Paris, France
| | - Paola Visconti
- IRCCS Istituto Delle Scienze Neurologiche di Bologna, UOSI Disturbi Dello Spettro Autistico, Bologna, Italy
| | - Elena Bacchelli
- Pharmacy and Biotechnology Department, University of Bologna, Bologna, Italy
| | - Elena Maestrini
- Pharmacy and Biotechnology Department, University of Bologna, Bologna, Italy
| | | | - Catherine Gooch
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA
| | - Yvonne Hendriks
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Hieab Adams
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Clinical Genetics, Erasmus MC, Rotterdam, the Netherlands
| | - Christel Thauvin-Robinet
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Dijon, France; Inserm, UMR1231, Equipe GAD, Bâtiment B3, Université de Bourgogne Franche Comté, Dijon Cedex, France; Centre de Référence Déficiences Intellectuelles de Causes Rares, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France
| | - Sarah Josephi-Taylor
- Department of Clinical Genetics, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Genomic Medicine, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Marta Bertoli
- Northern Genetics Service, Newcastle Upon Tyne NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Michael J Parker
- Department of Clinical Genetics, Sheffield Children's Hospital, Sheffield, UK
| | - Julie W Rutten
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
| | - Hilary J Vernon
- Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jonah Kaziyev
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jia Zhu
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jessica Kremen
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Zoe Frazier
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Hailey Osika
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - David Breault
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Sreelata Nair
- Department of Fetal Medicine, Lifeline Super Specialty Hospital, Kerala, India
| | - Suzanne M E Lewis
- Department of Medical Genetics, BC Children's Hospital Research Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Fabiola Ceroni
- Pharmacy and Biotechnology Department, University of Bologna, Bologna, Italy; Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK
| | - Marta Viggiano
- Pharmacy and Biotechnology Department, University of Bologna, Bologna, Italy
| | - Annio Posar
- IRCCS Istituto Delle Scienze Neurologiche di Bologna, UOSI Disturbi Dello Spettro Autistico, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Helen Brittain
- Department of Clinical Genetics, Birmingham Women's & Children's NHS Trust, Birmingham, UK
| | - Traficante Giovanna
- Medical Genetics Unit, Meyer Children's Hospital IRCCS Florence, Florence, Italy
| | - Gori Giulia
- Medical Genetics Unit,Meyer Children's Hospital IRCCS, Florence, Italy
| | - Lina Quteineh
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland
| | - Russia Ha-Vinh Leuchter
- Division of Development and Growth, Department of Pediatrics, University of Geneva, Geneva, Switzerland
| | - Evelien Zonneveld-Huijssoon
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Cecilia Mellado
- Sección de Genética y Errores Congénitos Del Metabolismo, División de Pediatría, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | | | - Mariana Inés Aracena Alvarez
- Unit of Genetics and Metabolic Diseases, Division of Pediatrics, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Milou G P Kennis
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Arianne Bouman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Maian Roifman
- The Prenatal Diagnosis and Medical Genetics Program, Division of Maternal Fetal Medicine, Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Canada
| | | | - Juan Dario Ortigoza-Escobar
- Movement Disorders Unit, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII and European Reference Network for Rare Neurological Diseases (ERN-RND), Barcelona, Spain
| | - Vivian Vernimmen
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, the Netherlands; GROW-School for Oncology and Reproduction, Maastricht, the Netherlands
| | - Margje Sinnema
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Han G Brunner
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Lisenka E L M Vissers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Tjitske Kleefstra
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Clinical Genetics, Erasmus MC, Rotterdam, the Netherlands; Center of Excellence for Neuropsychiatry, Vincent van Gogh Institute for Psychiatry, Venray, the Netherlands.
| | - Rosanna Weksberg
- Genetics and Genome Biology Program, Research Institute, the Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Division of Clinical and Metabolic Genetics, Department of Pediatrics, the Hospital for Sick Children, University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK; Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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Bertho M, Caldeira V, Hsu LJ, Löw P, Borgius L, Kiehn O. Excitatory Spinal Lhx9-Derived Interneurons Modulate Locomotor Frequency in Mice. J Neurosci 2024; 44:e1607232024. [PMID: 38438260 PMCID: PMC11063822 DOI: 10.1523/jneurosci.1607-23.2024] [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: 08/09/2023] [Revised: 01/18/2024] [Accepted: 02/15/2024] [Indexed: 03/06/2024] Open
Abstract
Locomotion allows us to move and interact with our surroundings. Spinal networks that control locomotion produce rhythm and left-right and flexor-extensor coordination. Several glutamatergic populations, Shox2 non-V2a, Hb9-derived interneurons, and, recently, spinocerebellar neurons have been proposed to be involved in the mouse rhythm generating networks. These cells make up only a smaller fraction of the excitatory cells in the ventral spinal cord. Here, we set out to identify additional populations of excitatory spinal neurons that may be involved in rhythm generation or other functions in the locomotor network. We use RNA sequencing from glutamatergic, non-glutamatergic, and Shox2 cells in the neonatal mice from both sexes followed by differential gene expression analyses. These analyses identified transcription factors that are highly expressed by glutamatergic spinal neurons and differentially expressed between Shox2 neurons and glutamatergic neurons. From this latter category, we identified the Lhx9-derived neurons as having a restricted spinal expression pattern with no Shox2 neuron overlap. They are purely glutamatergic and ipsilaterally projecting. Ablation of the glutamatergic transmission or acute inactivation of the neuronal activity of Lhx9-derived neurons leads to a decrease in the frequency of locomotor-like activity without change in coordination pattern. Optogenetic activation of Lhx9-derived neurons promotes locomotor-like activity and modulates the frequency of the locomotor activity. Calcium activities of Lhx9-derived neurons show strong left-right out-of-phase rhythmicity during locomotor-like activity. Our study identifies a distinct population of spinal excitatory neurons that regulates the frequency of locomotor output with a suggested role in rhythm-generation in the mouse alongside other spinal populations.
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Affiliation(s)
- Maëlle Bertho
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Vanessa Caldeira
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Li-Ju Hsu
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Peter Löw
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Lotta Borgius
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Ole Kiehn
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark
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McCallum-Loudeac J, Moody E, Williams J, Johnstone G, Sircombe KJ, Clarkson AN, Wilson MJ. Deletion of a conserved genomic region associated with adolescent idiopathic scoliosis leads to vertebral rotation in mice. Hum Mol Genet 2024; 33:787-801. [PMID: 38280229 PMCID: PMC11031364 DOI: 10.1093/hmg/ddae011] [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: 06/22/2023] [Revised: 12/15/2023] [Accepted: 01/12/2024] [Indexed: 01/29/2024] Open
Abstract
Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis, in which spinal curvature develops in adolescence, and 90% of patients are female. Scoliosis is a debilitating disease that often requires bracing or surgery in severe cases. AIS affects 2%-5.2% of the population; however, the biological origin of the disease remains poorly understood. In this study, we aimed to determine the function of a highly conserved genomic region previously linked to AIS using a mouse model generated by CRISPR-CAS9 gene editing to knockout this area of the genome to understand better its contribution to AIS, which we named AIS_CRMΔ. We also investigated the upstream factors that regulate the activity of this enhancer in vivo, whether the spatial expression of the LBX1 protein would change with the loss of AIS-CRM function, and whether any phenotype would arise after deletion of this region. We found a significant increase in mRNA expression in the developing neural tube at E10.5, and E12.5, for not only Lbx1 but also other neighboring genes. Adult knockout mice showed vertebral rotation and proprioceptive deficits, also observed in human AIS patients. In conclusion, our study sheds light on the elusive biological origins of AIS, by targeting and investigating a highly conserved genomic region linked to AIS in humans. These findings provide valuable insights into the function of the investigated region and contribute to our understanding of the underlying causes of this debilitating disease.
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Affiliation(s)
- Jeremy McCallum-Loudeac
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Edward Moody
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Jack Williams
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Georgia Johnstone
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Kathleen J Sircombe
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Andrew N Clarkson
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Megan J Wilson
- Department of Anatomy, School of Biomedical Sciences, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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Wilson AC, Sweeney LB. Spinal cords: Symphonies of interneurons across species. Front Neural Circuits 2023; 17:1146449. [PMID: 37180760 PMCID: PMC10169611 DOI: 10.3389/fncir.2023.1146449] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/23/2023] [Indexed: 05/16/2023] Open
Abstract
Vertebrate movement is orchestrated by spinal inter- and motor neurons that, together with sensory and cognitive input, produce dynamic motor behaviors. These behaviors vary from the simple undulatory swimming of fish and larval aquatic species to the highly coordinated running, reaching and grasping of mice, humans and other mammals. This variation raises the fundamental question of how spinal circuits have changed in register with motor behavior. In simple, undulatory fish, exemplified by the lamprey, two broad classes of interneurons shape motor neuron output: ipsilateral-projecting excitatory neurons, and commissural-projecting inhibitory neurons. An additional class of ipsilateral inhibitory neurons is required to generate escape swim behavior in larval zebrafish and tadpoles. In limbed vertebrates, a more complex spinal neuron composition is observed. In this review, we provide evidence that movement elaboration correlates with an increase and specialization of these three basic interneuron types into molecularly, anatomically, and functionally distinct subpopulations. We summarize recent work linking neuron types to movement-pattern generation across fish, amphibians, reptiles, birds and mammals.
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Affiliation(s)
| | - Lora B. Sweeney
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Lower Austria, Austria
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Schnerwitzki D, Englert C, Schmidt M. Adapting the pantograph limb: Differential robustness of fore- and hindlimb kinematics against genetically induced perturbation in the neural control networks and its evolutionary implications. ZOOLOGY 2023; 157:126076. [PMID: 36842298 DOI: 10.1016/j.zool.2023.126076] [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: 05/22/2021] [Revised: 01/28/2023] [Accepted: 02/07/2023] [Indexed: 02/19/2023]
Abstract
The evolutionary transformation of limb morphology to the four-segmented pantograph of therians is among the milestones of mammalian evolution. But, it is still unknown if changes of the mechanical limb function were accompanied by corresponding changes in development and sensorimotor control. The impressive locomotor performance of mammals leaves no doubt about the high integration of pattern formation, neural control and mechanics. But, deviations from normal intra- and interlimb coordination (spatial and temporal) become evident in the presence of perturbations. We induced a perturbation in the development of the neural circuits of the spinal cord of mice (Mus musculus) using a deletion of the Wilms tumor suppressor gene Wt1 in a subpopulation of dI6 interneurons. These interneurons are assumed to participate in the intermuscular coordination within the limb and in left-right-coordination between the limbs. We describe the locomotor kinematics in mice with conditional Wt1 knockout and compare them to mice without Wt1 deletion. Unlike knockout neonates, knockout adult mice do not display severe deviations from normal (=control group) interlimb coordination, but the coordinated protraction and retraction of the limbs is altered. The forelimbs are more affected by deviations from the control than the hindlimbs. This observation appears to reflect a different degree of integration and resistance against the induced perturbation between the limbs. Interestingly, the observed effects are similar to locomotor deficits reported to arise when sensory feedback from proprioceptors or cutaneous receptors is impaired. A putative participation of Wt1 positive dI6 interneurons in sensorimotor integration is therefore considered.
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Affiliation(s)
- Danny Schnerwitzki
- Molecular Genetics Lab, Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany.
| | - Christoph Englert
- Molecular Genetics Lab, Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany; Institute of Biochemistry and Biophysics, Friedrich-Schiller-University Jena, Jena, Germany.
| | - Manuela Schmidt
- Institute of Zoology and Evolutionary Research with Phyletic Museum, Ernst-Haeckel building and Didactics of Biology, Friedrich Schiller University Jena, Erbertstrasse 1, 07743 Jena, Germany.
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7
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Boato F, Guan X, Zhu Y, Ryu Y, Voutounou M, Rynne C, Freschlin CR, Zumbo P, Betel D, Matho K, Makarov SN, Wu Z, Son YJ, Nummenmaa A, Huang JZ, Edwards DJ, Zhong J. Activation of MAP2K signaling by genetic engineering or HF-rTMS promotes corticospinal axon sprouting and functional regeneration. Sci Transl Med 2023; 15:eabq6885. [PMID: 36599003 DOI: 10.1126/scitranslmed.abq6885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Facilitating axon regeneration in the injured central nervous system remains a challenging task. RAF-MAP2K signaling plays a key role in axon elongation during nervous system development. Here, we show that conditional expression of a constitutively kinase-activated BRAF in mature corticospinal neurons elicited the expression of a set of transcription factors previously implicated in the regeneration of zebrafish retinal ganglion cell axons and promoted regeneration and sprouting of corticospinal tract (CST) axons after spinal cord injury in mice. Newly sprouting axon collaterals formed synaptic connections with spinal interneurons, resulting in improved recovery of motor function. Noninvasive suprathreshold high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) activated the BRAF canonical downstream effectors MAP2K1/2 and modulated the expression of a set of regeneration-related transcription factors in a pattern consistent with that induced by BRAF activation. HF-rTMS enabled CST axon regeneration and sprouting, which was abolished in MAP2K1/2 conditional null mice. These data collectively demonstrate a central role of MAP2K signaling in augmenting the growth capacity of mature corticospinal neurons and suggest that HF-rTMS might have potential for treating spinal cord injury by modulating MAP2K signaling.
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Affiliation(s)
- Francesco Boato
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Xiaofei Guan
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Yanjie Zhu
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Youngjae Ryu
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Mariel Voutounou
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Christopher Rynne
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Chase R Freschlin
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Paul Zumbo
- Applied Bioinformatics Core, Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Doron Betel
- Applied Bioinformatics Core, Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Katie Matho
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Sergey N Makarov
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.,Electrical and Computer Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Zhuhao Wu
- Icahn School of Medicine at Mount Sinai, New York, NY 10065, USA
| | - Young-Jin Son
- Shriners Hospitals Pediatric Research Center, Temple University, Philadelphia, PA 19140, USA
| | - Aapo Nummenmaa
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Josh Z Huang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.,Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Dylan J Edwards
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Moss Rehabilitation Research Institute, Elkins Park, PA 19027, USA.,Thomas Jefferson University, Philadelphia, PA 19108, USA.,Exercise Medicine Research Institute, School of Biomedical and Health Sciences, Edith Cowan University, Joondalup 6027, Australia
| | - Jian Zhong
- Molecular Regeneration and Neuroimaging Laboratory, Burke Neurological Institute, White Plains, NY 10605, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
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8
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Vieillard J, Franck MCM, Hartung S, Jakobsson JET, Ceder MM, Welsh RE, Lagerström MC, Kullander K. Adult spinal Dmrt3 neurons receive direct somatosensory inputs from ipsi- and contralateral primary afferents and from brainstem motor nuclei. J Comp Neurol 2023; 531:5-24. [PMID: 36214727 PMCID: PMC9828095 DOI: 10.1002/cne.25405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/15/2022] [Accepted: 08/22/2022] [Indexed: 01/12/2023]
Abstract
In the spinal cord, sensory-motor circuits controlling motor activity are situated in the dorso-ventral interface. The neurons identified by the expression of the transcription factor Doublesex and mab-3 related transcription factor 3 (Dmrt3) have previously been associated with the coordination of locomotion in horses (Equus caballus, Linnaeus, 1758), mice (Mus musculus, Linnaeus, 1758), and zebrafish (Danio rerio, F. Hamilton, 1822). Based on earlier studies, we hypothesized that, in mice, these neurons may be positioned to receive sensory and central inputs to relay processed commands to motor neurons. Thus, we investigated the presynaptic inputs to spinal Dmrt3 neurons using monosynaptic retrograde replication-deficient rabies tracing. The analysis showed that lumbar Dmrt3 neurons receive inputs from intrasegmental neurons, and intersegmental neurons from the cervical, thoracic, and sacral segments. Some of these neurons belong to the excitatory V2a interneurons and to plausible Renshaw cells, defined by the expression of Chx10 and calbindin, respectively. We also found that proprioceptive primary sensory neurons of type Ia2, Ia3, and Ib, defined by the expression of calbindin, calretinin, and Brn3c, respectively, provide presynaptic inputs to spinal Dmrt3 neurons. In addition, we demonstrated that Dmrt3 neurons receive inputs from brain areas involved in motor regulation, including the red nucleus, primary sensory-motor cortex, and pontine nuclei. In conclusion, adult spinal Dmrt3 neurons receive inputs from motor-related brain areas as well as proprioceptive primary sensory neurons and have been shown to connect directly to motor neurons. Dmrt3 neurons are thus positioned to provide sensory-motor control and their connectivity is suggestive of the classical reflex pathways present in the spinal cord.
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Affiliation(s)
- Jennifer Vieillard
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Marina C. M. Franck
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden,Present address: Department of Medical Biochemistry and BiophysicsKarolinska InstitutetStockholmSweden
| | - Sunniva Hartung
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Jon E. T. Jakobsson
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Mikaela M. Ceder
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Robert E. Welsh
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Malin C. Lagerström
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Klas Kullander
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
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9
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Gosgnach S. Spinal inhibitory interneurons: regulators of coordination during locomotor activity. Front Neural Circuits 2023; 17:1167836. [PMID: 37151357 PMCID: PMC10159059 DOI: 10.3389/fncir.2023.1167836] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/06/2023] [Indexed: 05/09/2023] Open
Abstract
Since the early 1900's it has been known that a neural network, situated entirely within the spinal cord, is capable of generating the movements required for coordinated locomotion in limbed vertebrates. Due the number of interneurons in the spinal cord, and the extent to which neurons with the same function are intermingled with others that have divergent functions, the components of this neural circuit (now referred to as the locomotor central pattern generator-CPG) have long proven to be difficult to identify. Over the past 20 years a molecular approach has been incorporated to study the locomotor CPG. This approach has resulted in new information regarding the identity of its component interneurons, and their specific role during locomotor activity. In this mini review the role of the inhibitory interneuronal populations that have been shown to be involved in locomotor activity are described, and their specific role in securing left-right, and flexor extensor alternation is outlined. Understanding how these interneuronal populations are activated, modulated, and interact with one another will help us understand how locomotor behavior is produced. In addition, a deeper understanding of the structure and mechanism of function of the locomotor CPG has the potential to assist those developing strategies aimed at enhancing recovery of motor function in spinal cord injured patients.
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10
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Li WY, Deng LX, Zhai FG, Wang XY, Li ZG, Wang Y. Chx10+V2a interneurons in spinal motor regulation and spinal cord injury. Neural Regen Res 2022; 18:933-939. [PMID: 36254971 PMCID: PMC9827767 DOI: 10.4103/1673-5374.355746] [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: 11/05/2022] Open
Abstract
Chx10-expressing V2a (Chx10+V2a) spinal interneurons play a large role in the excitatory drive of motoneurons. Chemogenetic ablation studies have demonstrated the essential nature of Chx10+V2a interneurons in the regulation of locomotor initiation, maintenance, alternation, speed, and rhythmicity. The role of Chx10+V2a interneurons in locomotion and autonomic nervous system regulation is thought to be robust, but their precise role in spinal motor regulation and spinal cord injury have not been fully explored. The present paper reviews the origin, characteristics, and functional roles of Chx10+V2a interneurons with an emphasis on their involvement in the pathogenesis of spinal cord injury. The diverse functional properties of these cells have only been substantiated by and are due in large part to their integration in a variety of diverse spinal circuits. Chx10+V2a interneurons play an integral role in conferring locomotion, which integrates various corticospinal, mechanosensory, and interneuron pathways. Moreover, accumulating evidence suggests that Chx10+V2a interneurons also play an important role in rhythmic patterning maintenance, left-right alternation of central pattern generation, and locomotor pattern generation in higher order mammals, likely conferring complex locomotion. Consequently, the latest research has focused on postinjury transplantation and noninvasive stimulation of Chx10+V2a interneurons as a therapeutic strategy, particularly in spinal cord injury. Finally, we review the latest preclinical study advances in laboratory derivation and stimulation/transplantation of these cells as a strategy for the treatment of spinal cord injury. The evidence supports that the Chx10+V2a interneurons act as a new therapeutic target for spinal cord injury. Future optimization strategies should focus on the viability, maturity, and functional integration of Chx10+V2a interneurons transplanted in spinal cord injury foci.
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Affiliation(s)
- Wen-Yuan Li
- Institute of Neural Tissue Engineering, Mudanjiang College of Medicine, Mudanjiang, Heilongjiang Province, China
| | - Ling-Xiao Deng
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Feng-Guo Zhai
- Department of Pharmacy, Mudanjiang College of Medicine, Mudanjiang, Heilongjiang Province, China
| | - Xiao-Yu Wang
- Institute of Neural Tissue Engineering, Mudanjiang College of Medicine, Mudanjiang, Heilongjiang Province, China
| | - Zhi-Gang Li
- Department of General Surgery, Hongqi Hospital, Mudanjiang College of Medicine, Mudanjiang, Heilongjiang Province, China,Correspondence to: Ying Wang, ; Zhi-Gang Li, .
| | - Ying Wang
- Institute of Neural Tissue Engineering, Mudanjiang College of Medicine, Mudanjiang, Heilongjiang Province, China,Correspondence to: Ying Wang, ; Zhi-Gang Li, .
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11
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Hopfenmüller VL, Perner B, Reuter H, Bates TJD, Große A, Englert C. The Wilms Tumor Gene wt1a Contributes to Blood-Cerebrospinal Fluid Barrier Function in Zebrafish. Front Cell Dev Biol 2022; 9:809962. [PMID: 35087838 PMCID: PMC8786916 DOI: 10.3389/fcell.2021.809962] [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] [Received: 11/05/2021] [Accepted: 12/07/2021] [Indexed: 11/30/2022] Open
Abstract
The Wilms tumor suppressor gene Wt1 encodes a zinc finger transcription factor, which is highly conserved among vertebrates. It is a key regulator of urogenital development and homeostasis but also plays a role in other organs including the spleen and the heart. More recently additional functions for Wt1 in the mammalian central nervous system have been described. In contrast to mammals, bony fish possess two paralogous Wt1 genes, namely wt1a and wt1b. By performing detailed in situ hybridization analyses during zebrafish development, we discovered new expression domains for wt1a in the dorsal hindbrain, the caudal medulla and the spinal cord. Marker analysis identified wt1a expressing cells of the dorsal hindbrain as ependymal cells of the choroid plexus in the myelencephalic ventricle. The choroid plexus acts as a blood-cerebrospinal fluid barrier and thus is crucial for brain homeostasis. By employing wt1a mutant larvae and a dye accumulation assay with fluorescent tracers we demonstrate that Wt1a is required for proper choroid plexus formation and function. Thus, Wt1a contributes to the barrier properties of the choroid plexus in zebrafish, revealing an unexpected role for Wt1 in the zebrafish brain.
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Affiliation(s)
| | - Birgit Perner
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena, Germany
| | - Hanna Reuter
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena, Germany
| | - Thomas J D Bates
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena, Germany
| | - Andreas Große
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena, Germany
| | - Christoph Englert
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena, Germany.,Institute of Biochemistry and Biophysics, Friedrich-Schiller-University Jena, Jena, Germany
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12
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Hirsch D, Kohl A, Wang Y, Sela-Donenfeld D. Axonal Projection Patterns of the Dorsal Interneuron Populations in the Embryonic Hindbrain. Front Neuroanat 2022; 15:793161. [PMID: 35002640 PMCID: PMC8738170 DOI: 10.3389/fnana.2021.793161] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
Unraveling the inner workings of neural circuits entails understanding the cellular origin and axonal pathfinding of various neuronal groups during development. In the embryonic hindbrain, different subtypes of dorsal interneurons (dINs) evolve along the dorsal-ventral (DV) axis of rhombomeres and are imperative for the assembly of central brainstem circuits. dINs are divided into two classes, class A and class B, each containing four neuronal subgroups (dA1-4 and dB1-4) that are born in well-defined DV positions. While all interneurons belonging to class A express the transcription factor Olig3 and become excitatory, all class B interneurons express the transcription factor Lbx1 but are diverse in their excitatory or inhibitory fate. Moreover, within every class, each interneuron subtype displays its own specification genes and axonal projection patterns which are required to govern the stage-by-stage assembly of their connectivity toward their target sites. Remarkably, despite the similar genetic landmark of each dINs subgroup along the anterior-posterior (AP) axis of the hindbrain, genetic fate maps of some dA/dB neuronal subtypes uncovered their contribution to different nuclei centers in relation to their rhombomeric origin. Thus, DV and AP positional information has to be orchestrated in each dA/dB subpopulation to form distinct neuronal circuits in the hindbrain. Over the span of several decades, different axonal routes have been well-documented to dynamically emerge and grow throughout the hindbrain DV and AP positions. Yet, the genetic link between these distinct axonal bundles and their neuronal origin is not fully clear. In this study, we reviewed the available data regarding the association between the specification of early-born dorsal interneuron subpopulations in the hindbrain and their axonal circuitry development and fate, as well as the present existing knowledge on molecular effectors underlying the process of axonal growth.
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Affiliation(s)
- Dana Hirsch
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.,Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Ayelet Kohl
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Yuan Wang
- Department of Biomedical Sciences, Program in Neuroscience, College of Medicine, Florida State University, Tallahassee, FL, United States
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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13
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Ong-Pålsson E, Njavro JR, Wilson Y, Pigoni M, Schmidt A, Müller SA, Meyer M, Hartmann J, Busche MA, Gunnersen JM, Munro KM, Lichtenthaler SF. The β-Secretase Substrate Seizure 6-Like Protein (SEZ6L) Controls Motor Functions in Mice. Mol Neurobiol 2021; 59:1183-1198. [PMID: 34958451 PMCID: PMC8857007 DOI: 10.1007/s12035-021-02660-y] [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] [Received: 08/11/2021] [Accepted: 11/20/2021] [Indexed: 11/03/2022]
Abstract
The membrane protein seizure 6-like (SEZ6L) is a neuronal substrate of the Alzheimer's disease protease BACE1, and little is known about its physiological function in the nervous system. Here, we show that SEZ6L constitutive knockout mice display motor phenotypes in adulthood, including changes in gait and decreased motor coordination. Additionally, SEZ6L knockout mice displayed increased anxiety-like behaviour, although spatial learning and memory in the Morris water maze were normal. Analysis of the gross anatomy and proteome of the adult SEZ6L knockout cerebellum did not reveal any major differences compared to wild type, indicating that lack of SEZ6L in other regions of the nervous system may contribute to the phenotypes observed. In summary, our study establishes physiological functions for SEZ6L in regulating motor coordination and curbing anxiety-related behaviour, indicating that aberrant SEZ6L function in the human nervous system may contribute to movement disorders and neuropsychiatric diseases.
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Affiliation(s)
- Emma Ong-Pålsson
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Jasenka Rudan Njavro
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Yvette Wilson
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Martina Pigoni
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Andree Schmidt
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig Maximilian University, Munich, Germany
| | - Stephan A Müller
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Michael Meyer
- Biomedical Center, Ludwig Maximilian University Munich, 82152, Planegg/Munich, Germany
| | - Jana Hartmann
- UK Dementia Research Institute at UCL, University College London, Great Britain, London, WC1E 6BT, UK.,Institute of Neuroscience, Technical University of Munich, 80802, Munich, Germany
| | - Marc Aurel Busche
- UK Dementia Research Institute at UCL, University College London, Great Britain, London, WC1E 6BT, UK
| | - Jenny M Gunnersen
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia.,The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Kathryn M Munro
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Stefan F Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany. .,Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675, Munich, Germany. .,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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14
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Iglesias González AB, Jakobsson JET, Vieillard J, Lagerström MC, Kullander K, Boije H. Single Cell Transcriptomic Analysis of Spinal Dmrt3 Neurons in Zebrafish and Mouse Identifies Distinct Subtypes and Reveal Novel Subpopulations Within the dI6 Domain. Front Cell Neurosci 2021; 15:781197. [PMID: 35002627 PMCID: PMC8733252 DOI: 10.3389/fncel.2021.781197] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/15/2021] [Indexed: 11/15/2022] Open
Abstract
The spinal locomotor network is frequently used for studies into how neuronal circuits are formed and how cellular activity shape behavioral patterns. A population of dI6 interneurons, marked by the Doublesex and mab-3 related transcription factor 3 (Dmrt3), has been shown to participate in the coordination of locomotion and gaits in horses, mice and zebrafish. Analyses of Dmrt3 neurons based on morphology, functionality and the expression of transcription factors have identified different subtypes. Here we analyzed the transcriptomes of individual cells belonging to the Dmrt3 lineage from zebrafish and mice to unravel the molecular code that underlies their subfunctionalization. Indeed, clustering of Dmrt3 neurons based on their gene expression verified known subtypes and revealed novel populations expressing unique markers. Differences in birth order, differential expression of axon guidance genes, neurotransmitters, and their receptors, as well as genes affecting electrophysiological properties, were identified as factors likely underlying diversity. In addition, the comparison between fish and mice populations offers insights into the evolutionary driven subspecialization concomitant with the emergence of limbed locomotion.
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Affiliation(s)
| | | | | | | | | | - Henrik Boije
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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15
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Decourtye L, McCallum-Loudeac JA, Zellhuber-McMillan S, Young E, Sircombe KJ, Wilson MJ. Characterization of a novel Lbx1 mouse loss of function strain. Differentiation 2021; 123:30-41. [PMID: 34906895 DOI: 10.1016/j.diff.2021.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/01/2021] [Accepted: 12/06/2021] [Indexed: 12/13/2022]
Abstract
Adolescent Idiopathic Scoliosis (AIS) is the most common type of spine deformity affecting 2-3% of the population worldwide. The etiology of this disease is still poorly understood. Several GWAS studies have identified single nucleotide polymorphisms (SNPs) located near the gene LBX1 that is significantly correlated with AIS risk. LBX1 is a transcription factor with roles in myocyte precursor migration, cardiac neural crest specification, and neuronal fate determination in the neural tube. Here, we further investigated the role of LBX1 in the developing spinal cord of mouse embryos using a CRISPR-generated mouse model expressing a truncated version of LBX1 (Lbx1Δ). Homozygous mice died at birth, likely due to cardiac abnormalities. To further study the neural tube phenotype, we used RNA-sequencing to identify 410 genes differentially expressed between the neural tubes of E12.5 wildtype and Lbx1Δ/Δ embryos. Genes with increased expression in the deletion line were involved in neurogenesis and those with broad roles in embryonic development. Many of these genes have also been associated with scoliotic phenotypes. In comparison, genes with decreased expression were primarily involved in skeletal development. Subsequent skeletal and immunohistochemistry analysis further confirmed these results. This study aids in understanding the significance of links between LBX1 function and AIS susceptibility.
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Affiliation(s)
- Lyvianne Decourtye
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand
| | - Jeremy A McCallum-Loudeac
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand
| | - Sylvia Zellhuber-McMillan
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand
| | - Emma Young
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand
| | - Kathleen J Sircombe
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand
| | - Megan J Wilson
- Department of Anatomy, School of Biomedical Sciences, University of Otago, 9054, Dunedin, New Zealand.
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Every Beat You Take-The Wilms' Tumor Suppressor WT1 and the Heart. Int J Mol Sci 2021; 22:ijms22147675. [PMID: 34299295 PMCID: PMC8306835 DOI: 10.3390/ijms22147675] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/06/2021] [Accepted: 07/16/2021] [Indexed: 12/23/2022] Open
Abstract
Nearly three decades ago, the Wilms’ tumor suppressor Wt1 was identified as a crucial regulator of heart development. Wt1 is a zinc finger transcription factor with multiple biological functions, implicated in the development of several organ systems, among them cardiovascular structures. This review summarizes the results from many research groups which allowed to establish a relevant function for Wt1 in cardiac development and disease. During development, Wt1 is involved in fundamental processes as the formation of the epicardium, epicardial epithelial-mesenchymal transition, coronary vessel development, valve formation, organization of the cardiac autonomous nervous system, and formation of the cardiac ventricles. Wt1 is further implicated in cardiac disease and repair in adult life. We summarize here the current knowledge about expression and function of Wt1 in heart development and disease and point out controversies to further stimulate additional research in the areas of cardiac development and pathophysiology. As re-activation of developmental programs is considered as paradigm for regeneration in response to injury, understanding of these processes and the molecules involved therein is essential for the development of therapeutic strategies, which we discuss on the example of WT1.
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Unusual Quadrupedal Locomotion in Rat during Recovery from Lumbar Spinal Blockade of 5-HT 7 Receptors. Int J Mol Sci 2021; 22:ijms22116007. [PMID: 34199392 PMCID: PMC8199611 DOI: 10.3390/ijms22116007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 01/18/2023] Open
Abstract
Coordination of four-limb movements during quadrupedal locomotion is controlled by supraspinal monoaminergic descending pathways, among which serotoninergic ones play a crucial role. Here we investigated the locomotor pattern during recovery from blockade of 5-HT7 or 5-HT2A receptors after intrathecal application of SB269970 or cyproheptadine in adult rats with chronic intrathecal cannula implanted in the lumbar spinal cord. The interlimb coordination was investigated based on electromyographic activity recorded from selected fore- and hindlimb muscles during rat locomotion on a treadmill. In the time of recovery after hindlimb transient paralysis, we noticed a presence of an unusual pattern of quadrupedal locomotion characterized by a doubling of forelimb stepping in relation to unaffected hindlimb stepping (2FL-1HL) after blockade of 5-HT7 receptors but not after blockade of 5-HT2A receptors. The 2FL-1HL pattern, although transient, was observed as a stable form of fore-hindlimb coupling during quadrupedal locomotion. We suggest that modulation of the 5-HT7 receptors on interneurons located in lamina VII with ascending projections to the forelimb spinal network can be responsible for the 2FL-1HL locomotor pattern. In support, our immunohistochemical analysis of the lumbar spinal cord demonstrated the presence of the 5-HT7 immunoreactive cells in the lamina VII, which were rarely 5-HT2A immunoreactive.
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Implications of the Wilms' Tumor Suppressor Wt1 in Cardiomyocyte Differentiation. Int J Mol Sci 2021; 22:ijms22094346. [PMID: 33919406 PMCID: PMC8122684 DOI: 10.3390/ijms22094346] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022] Open
Abstract
The Wilms’ tumor suppressor Wt1 is involved in multiple developmental processes and adult tissue homeostasis. The first phenotypes recognized in Wt1 knockout mice were developmental cardiac and kidney defects. Wt1 expression in the heart has been described in epicardial, endothelial, smooth muscle cells, and fibroblasts. Expression of Wt1 in cardiomyocytes has been suggested but remained a controversial issue, as well as the role of Wt1 in cardiomyocyte development and regeneration after injury. We determined cardiac Wt1 expression during embryonic development, in the adult, and after cardiac injury by quantitative RT-PCR and immunohistochemistry. As in vitro model, phenotypic cardiomyocyte differentiation, i.e., the appearance of rhythmically beating clones from mouse embryonic stem cells (mESCs) and associated changes in gene expression were analyzed. We detected Wt1 in cardiomyocytes from embryonic day (E10.5), the first time point investigated, until adult age. Cardiac Wt1 mRNA levels decreased during embryonic development. In the adult, Wt1 was reactivated in cardiomyocytes 48 h and 3 weeks following myocardial infarction. Wt1 mRNA levels were increased in differentiating mESCs. Overexpression of Wt1(-KTS) and Wt1(+KTS) isoforms in ES cells reduced the fraction of phenotypically cardiomyocyte differentiated clones, which was preceded by a temporary increase in c-kit expression in Wt1(-KTS) transfected ES cell clones and induction of some cardiomyocyte markers. Taken together, Wt1 shows a dynamic expression pattern during cardiomyocyte differentiation and overexpression in ES cells reduces their phenotypical cardiomyocyte differentiation.
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Schnerwitzki D, Hayn C, Perner B, Englert C. Wt1 Positive dB4 Neurons in the Hindbrain Are Crucial for Respiration. Front Neurosci 2020; 14:529487. [PMID: 33328840 PMCID: PMC7734174 DOI: 10.3389/fnins.2020.529487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 11/10/2020] [Indexed: 02/02/2023] Open
Abstract
Central pattern generator (CPG) networks coordinate the generation of rhythmic activity such as locomotion and respiration. Their development is driven by various transcription factors, one of which is the Wilms tumor protein (Wt1). It is present in dI6 neurons of the mouse spinal cord, and involved in the coordination of locomotion. Here we report about the presence of Wt1 in neurons of the caudoventral medulla oblongata and their impact on respiration. By employing immunohistofluorescence staining, we were able to characterize these Wt1 positive (+) cells as dB4 neurons. The temporal occurrence of Wt1 suggests a role for this transcription factor in the differentiation of dB4 neurons during embryonic and postnatal development. Conditional knockout of Wt1 in these cells caused an altered population size of V0 neurons already in the developing hindbrain, leading to a decline in the respiration rate in the adults. Thereby, we confirmed and extended the previously proposed similarity between dB4 neurons in the hindbrain and dI6 neurons of the spinal cord, in terms of development and function. Ablation of Wt1+ dB4 neurons resulted in the death of neonates due to the inability to initiate respiration, suggesting a vital role for Wt1+ dB4 neurons in breathing. These results expand the role of Wt1 in the CNS and show that, in addition to its function in differentiation of dI6 neurons, it also contributes to the development of dB4 neurons in the hindbrain that are critically involved in the regulation of respiration.
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Affiliation(s)
- Danny Schnerwitzki
- Molecular Genetics Laboratory, Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Christian Hayn
- Molecular Genetics Laboratory, Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Birgit Perner
- Molecular Genetics Laboratory, Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany.,Core Facility Imaging, Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Christoph Englert
- Molecular Genetics Laboratory, Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany.,Institute of Biochemistry and Biophysics, Friedrich-Schiller-University Jena, Jena, Germany
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Zavvarian MM, Hong J, Fehlings MG. The Functional Role of Spinal Interneurons Following Traumatic Spinal Cord Injury. Front Cell Neurosci 2020; 14:127. [PMID: 32528250 PMCID: PMC7247430 DOI: 10.3389/fncel.2020.00127] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 04/17/2020] [Indexed: 12/17/2022] Open
Abstract
Traumatic spinal cord injury (SCI) impedes signal transmission by disrupting both the local neurons and their surrounding synaptic connections. Although the majority of SCI patients retain spared neural tissue at the injury site, they predominantly suffer from complete autonomic and sensorimotor dysfunction. While there have been significant advances in the characterization of the spared neural tissue following SCI, the functional role of injury-induced interneuronal plasticity remains elusive. In healthy individuals, spinal interneurons are responsible for relaying signals to coordinate both sympathetic and parasympathetic functions. However, the spontaneous synaptic loss following injury alters these intricate interneuronal networks in the spinal cord. Here, we propose the synaptopathy hypothesis of SCI based on recent findings regarding the maladaptive role of synaptic changes amongst the interneurons. These maladaptive consequences include circuit inactivation, neuropathic pain, spasticity, and autonomic dysreflexia. Recent preclinical advances have uncovered the therapeutic potential of spinal interneurons in activating the dormant relay circuits to restore sensorimotor function. This review will survey the diverse role of spinal interneurons in SCI pathogenesis as well as treatment strategies to target spinal interneurons.
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Affiliation(s)
- Mohammad-Masoud Zavvarian
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - James Hong
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael G Fehlings
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Division of Neurosurgery, University of Toronto, Toronto, ON, Canada
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Behavioral Characterization of dmrt3a Mutant Zebrafish Reveals Crucial Aspects of Vertebrate Locomotion through Phenotypes Related to Acceleration. eNeuro 2020; 7:ENEURO.0047-20.2020. [PMID: 32357958 PMCID: PMC7235372 DOI: 10.1523/eneuro.0047-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/02/2020] [Accepted: 04/19/2020] [Indexed: 12/16/2022] Open
Abstract
Vertebrate locomotion is orchestrated by spinal interneurons making up a central pattern generator. Proper coordination of activity, both within and between segments, is required to generate the desired locomotor output. This coordination is altered during acceleration to ensure the correct recruitment of muscles for the chosen speed. The transcription factor Dmrt3 has been proposed to shape the patterned output at different gaits in horses and mice. Vertebrate locomotion is orchestrated by spinal interneurons making up a central pattern generator. Proper coordination of activity, both within and between segments, is required to generate the desired locomotor output. This coordination is altered during acceleration to ensure the correct recruitment of muscles for the chosen speed. The transcription factor Dmrt3 has been proposed to shape the patterned output at different gaits in horses and mice. Here, we characterized dmrt3a mutant zebrafish, which showed a strong, transient, locomotor phenotype in developing larvae. During beat-and-glide swimming, mutant larvae showed fewer and shorter movements with decreased velocity and acceleration. Developmental compensation likely occurs as the analyzed behaviors did not differ from wild-type at older larval stages. However, analysis of maximum swim speed in juveniles suggests that some defects persist within the mature locomotor network of dmrt3a mutants. Our results reveal the pivotal role Dmrt3 neurons play in shaping the patterned output during acceleration in vertebrates.
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Masgutova G, Harris A, Jacob B, Corcoran LM, Clotman F. Pou2f2 Regulates the Distribution of Dorsal Interneurons in the Mouse Developing Spinal Cord. Front Mol Neurosci 2019; 12:263. [PMID: 31787878 PMCID: PMC6853997 DOI: 10.3389/fnmol.2019.00263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022] Open
Abstract
Spinal dorsal interneurons, which are generated during embryonic development, relay and process sensory inputs from the periphery to the central nervous system. Proper integration of these cells into neuronal circuitry depends on their correct positioning within the spinal parenchyma. Molecular cues that control neuronal migration have been extensively characterized but the genetic programs that regulate their production remain poorly investigated. Onecut (OC) transcription factors have been shown to control the migration of the dorsal interneurons (dINs) during spinal cord development. Here, we report that the OC factors moderate the expression of Pou2f2, a transcription factor essential for B-cell differentiation, in spinal dINs. Overexpression or inactivation of Pou2f2 leads to alterations in the differentiation of dI2, dI3 and Phox2a-positive dI5 populations and to defects in the distribution of dI2-dI6 interneurons. Thus, an OC-Pou2f2 genetic cascade regulates adequate diversification and distribution of dINs during embryonic development.
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Affiliation(s)
- Gauhar Masgutova
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, Belgium
| | - Audrey Harris
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, Belgium
| | - Benvenuto Jacob
- Université catholique de Louvain, Institute of Neuroscience, System and Cognition Division, Brussels, Belgium
| | - Lynn M Corcoran
- Molecular Immunology Division and Immunology Division, The Walter and Eliza Hall Institute, Parkville, VIC, Australia
| | - Frédéric Clotman
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, Belgium
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Characterization of Dmrt3-Derived Neurons Suggest a Role within Locomotor Circuits. J Neurosci 2018; 39:1771-1782. [PMID: 30578339 DOI: 10.1523/jneurosci.0326-18.2018] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 11/27/2018] [Accepted: 12/10/2018] [Indexed: 11/21/2022] Open
Abstract
Neuronal networks within the spinal cord, collectively known as the central pattern generator (CPG), coordinate rhythmic movements underlying locomotion. The transcription factor doublesex and mab-3-related transcription factor 3 (DMRT3) is involved in the differentiation of the dorsal interneuron 6 class of spinal cord interneurons. In horses, a non-sense mutation in the Dmrt3 gene has major effects on gaiting ability, whereas mice lacking the Dmrt3 gene display impaired locomotor activity. Although the Dmrt3 gene is necessary for normal spinal network formation and function in mice, a direct role for Dmrt3-derived neurons in locomotor-related activities has not been demonstrated. Here we present the characteristics of the Dmrt3-derived spinal cord interneurons. Using transgenic mice of both sexes, we characterized interneurons labeled by their expression of Cre driven by the endogenous Dmrt3 promoter. We used molecular, retrograde tracing and electrophysiological techniques to examine the anatomical, morphological, and electrical properties of the Dmrt3-Cre neurons. We demonstrate that inhibitory Dmrt3-Cre neurons receive extensive synaptic inputs, innervate surrounding CPG neurons, intrinsically regulate CPG neuron's electrical activity, and are rhythmically active during fictive locomotion, bursting at frequencies independent to the ventral root output. The present study provides novel insights on the character of spinal Dmrt3-derived neurons, data demonstrating that these neurons participate in locomotor coordination.SIGNIFICANCE STATEMENT In this work, we provide evidence for a role of the Dmrt3 interneurons in spinal cord locomotor circuits as well as molecular and functional insights on the cellular and microcircuit level of the Dmrt3-expressing neurons in the spinal cord. Dmrt3 neurons provide the first example of an interneuron population displaying different oscillation frequencies. This study presents novel findings on an under-reported population of spinal cord neurons, which will aid in deciphering the locomotor network and will facilitate the design and development of therapeutics for spinal cord injury and motor disorders.
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