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Munoz-Gualan AP, Güngör A, Cezayirli PC, Rahmanov S, Gurses ME, Puelles L, Türe U. Human Adapted Prosomeric Model: A Future for Brainstem Tumor Classification. Brain Res 2024; 1837:148961. [PMID: 38679312 DOI: 10.1016/j.brainres.2024.148961] [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: 12/12/2023] [Revised: 03/30/2024] [Accepted: 04/24/2024] [Indexed: 05/01/2024]
Abstract
This study reevaluates the conventional understanding of midbrain anatomy and neuroanatomical nomenclature in the context of recent genetic and anatomical discoveries. The authors assert that the midbrain should be viewed as an integral part of the forebrain due to shared genetic determinants and evolutionary lineage. The isthmo-mesencephalic boundary is recognized as a significant organizer for both the caudal midbrain and the isthmo-cerebellar area. The article adopts the prosomeric model, redefining the whole brain as neuromeres, offering a more precise depiction of brain development, including processes like proliferation, neurogenesis, cell migration, and differentiation. This shift in understanding challenges traditional definitions of the midbrain based on external brain morphology. The study also delves into the historical context of neuroanatomical models, including the columnar model proposed by Herrick in 1910, which has influenced our understanding of brain structure. Furthermore, the study has clinical implications, affecting neuroanatomy, neurodevelopmental studies, and the diagnosis and treatment of brain disorders. It emphasizes the need to integrate molecular research into human neuroanatomical studies and advocates for updating neuroanatomical terminology to reflect modern genetic and molecular insights. The authors propose two key revisions. First, we suggest reclassifying the isthmo-cerebellar prepontine region as part of the hindbrain, due to its role in cerebellar development and distinct location caudal to the genetically-defined midbrain. Second, we recommend redefining the anterior boundary of the genetically-defined midbrain to align with genetic markers. In conclusion, the authors highlight the importance of harmonizing neuroanatomical nomenclature with current scientific knowledge, promoting a more precise and informed understanding of brain structure, which is crucial for both research and clinical applications related to the human brain.
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Affiliation(s)
| | - Abuzer Güngör
- Department of Neurosurgery, Yeditepe University School of Medicine, Istanbul, Turkey; Department of Neurosurgery, Istinye University, Istanbul, Turkey
| | - Phillip Cem Cezayirli
- Department of Neurosurgery, Yeditepe University School of Medicine, Istanbul, Turkey; Haynes Neurosurgical Group, Birmingham, AL, United States
| | - Serdar Rahmanov
- Department of Neurosurgery, Yeditepe University School of Medicine, Istanbul, Turkey
| | - Muhammet Enes Gurses
- Department of Neurosurgery, Yeditepe University School of Medicine, Istanbul, Turkey; Department of Neurosurgery, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain; Institute of Biomedical Research of Murcia -IMIB, Virgen de la Arrixaca University Hospital, Murcia, Spain
| | - Uğur Türe
- Department of Neurosurgery, Yeditepe University School of Medicine, Istanbul, Turkey.
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2
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Finszter CK, Kemecsei R, Zachar G, Holtkamp S, Echevarría D, Adorján I, Ádám Á, Csillag A. Early cellular and synaptic changes in dopaminoceptive forebrain regions of juvenile mice following gestational exposure to valproate. Front Neuroanat 2023; 17:1235047. [PMID: 37603782 PMCID: PMC10435871 DOI: 10.3389/fnana.2023.1235047] [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: 06/05/2023] [Accepted: 07/19/2023] [Indexed: 08/23/2023] Open
Abstract
Gestational exposure of mice to valproic acid (VPA) is one currently used experimental model for the investigation of typical failure symptoms associated with autism spectrum disorder (ASD). In the present study we hypothesized that the reduction of dopaminergic source neurons of the VTA, followed by perturbed growth of the mesotelencephalic dopamine pathway (MT), should also modify pattern formation in the dopaminoceptive target regions (particularly its mesoaccumbens/mesolimbic portion). Here, we investigated VPA-evoked cellular morphological (apoptosis-frequency detected by Caspase-3, abundance of Ca-binding proteins, CaBP), as well as synaptic proteomic (western blotting) changes, in selected dopaminoceptive subpallial, as compared to pallial, regions of mice, born to mothers treated with 500 mg/kg VPA on day 13.5 of pregnancy. We observed a surge of apoptosis on VPA treatment in nearly all investigated subpallial and pallial regions; with a non-significant trend of similar increase the nucleus accumbens (NAc) at P7, the age at which the MT pathway reduction has been reported (also supplemented by current findings). Of the CaBPs, calretinin (CR) expression was decreased in pallial regions, most prominently in retrosplenial cortex, but not in the subpallium of P7 mice. Calbindin-D 28K (CB) was selectively reduced in the caudate-putamen (CPu) of VPA exposed animals at P7 but no longer at P60, pointing to a potency of repairment. The VPA-associated overall increase in apoptosis at P7 did not correlate with the abundance and distribution of CaBPs, except in CPu, in which the marked drop of CB was negatively correlated with increased apoptosis. Abundance of parvalbumin (PV) at P60 showed no significant response to VPA treatment in any of the observed regions we did not find colocalization of apoptotic (Casp3+) cells with CaBP-immunoreactive neurons. The proteomic findings suggest reduction of tyrosine hydroxylase in the crude synaptosome fraction of NAc, but not in the CPu, without simultaneous decrease of the synaptic protein, synaptophysin, indicating selective impairment of dopaminergic synapses. The morpho-functional changes found in forebrain regions of VPA-exposed mice may signify dendritic and synaptic reorganization in dopaminergic target regions, with potential translational value to similar impairments in the pathogenesis of human ASD.
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Affiliation(s)
- Cintia Klaudia Finszter
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Róbert Kemecsei
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergely Zachar
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Sophie Holtkamp
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Diego Echevarría
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - István Adorján
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Ágota Ádám
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - András Csillag
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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3
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Zhao P, Jiang T, Wang H, Jia X, Li A, Gong H, Li X. Upper brainstem cholinergic neurons project to ascending and descending circuits. BMC Biol 2023; 21:135. [PMID: 37280580 DOI: 10.1186/s12915-023-01625-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 05/12/2023] [Indexed: 06/08/2023] Open
Abstract
BACKGROUND Based on their anatomical location, rostral projections of nuclei are classified as ascending circuits, while caudal projections are classified as descending circuits. Upper brainstem neurons participate in complex information processing and specific sub-populations preferentially project to participating ascending or descending circuits. Cholinergic neurons in the upper brainstem have extensive collateralizations in both ascending and descending circuits; however, their single-cell projection patterns remain unclear because of the lack of comprehensive characterization of individual neurons. RESULTS By combining fluorescent micro-optical sectional tomography with sparse labeling, we acquired a high-resolution whole-brain dataset of pontine-tegmental cholinergic neurons (PTCNs) and reconstructed their detailed morphology using semi-automatic reconstruction methods. As the main source of acetylcholine in some subcortical areas, individual PTCNs had abundant axons with lengths up to 60 cm and 5000 terminals and innervated multiple brain regions from the spinal cord to the cortex in both hemispheres. Based on various collaterals in the ascending and descending circuits, individual PTCNs were grouped into four subtypes. The morphology of cholinergic neurons in the pedunculopontine nucleus was more divergent, whereas the laterodorsal tegmental nucleus neurons contained richer axonal branches and dendrites. In the ascending circuits, individual PTCNs innervated the thalamus in three different patterns and projected to the cortex via two separate pathways. Moreover, PTCNs targeting the ventral tegmental area and substantia nigra had abundant collaterals in the pontine reticular nuclei, and these two circuits contributed oppositely to locomotion. CONCLUSIONS Our results suggest that individual PTCNs have abundant axons, and most project to various collaterals in the ascending and descending circuits simultaneously. They target regions with multiple patterns, such as the thalamus and cortex. These results provide a detailed organizational characterization of cholinergic neurons to understand the connexional logic of the upper brainstem.
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Affiliation(s)
- Peilin Zhao
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute of neurological diseases, North Sichuan Medical University, Nanchong, 637100, China
| | - Tao Jiang
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Sciences, HUST-Suzhou Institute for Brainsmatics, JITRI, Suzhou, 215123, China
| | - Huading Wang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xueyan Jia
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Sciences, HUST-Suzhou Institute for Brainsmatics, JITRI, Suzhou, 215123, China
| | - Anan Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, 430074, China
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Sciences, HUST-Suzhou Institute for Brainsmatics, JITRI, Suzhou, 215123, China
| | - Hui Gong
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, 430074, China
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Sciences, HUST-Suzhou Institute for Brainsmatics, JITRI, Suzhou, 215123, China
| | - Xiangning Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, 430074, China.
- Research Unit of Multimodal Cross Scale Neural Signal Detection and Imaging, Chinese Academy of Medical Sciences, HUST-Suzhou Institute for Brainsmatics, JITRI, Suzhou, 215123, China.
- Key Laboratory of Biomedical Engineering of Hainan Province, School of Biomedical Engineering, Hainan University, Haikou, 570228, China.
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García-Guillén IM, Aroca P, Marín F. Molecular identity of the lateral lemniscus nuclei in the adult mouse brain. Front Neuroanat 2023; 17:1098352. [PMID: 36999169 PMCID: PMC10044012 DOI: 10.3389/fnana.2023.1098352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/20/2023] [Indexed: 03/11/2023] Open
Abstract
IntroductionThe dorsal (DLL), intermediate (ILL), and ventral (VLL) lateral lemniscus nuclei are relay centers in the central auditory pathway of the brainstem, commonly referred to as the lateral lemniscus nuclei (LLN). The LLN are situated in the prepontine and pontine hindbrain, from rhombomeres 1 to 4, extending from the more rostral DLL to the caudal VLL, with the ILL lying in between. These nuclei can be distinguished morphologically and by topological and connectivity criteria, and here, we set out to further characterize the molecular nature of each LLN.MethodsWe searched in situ hybridization studies in the Allen Mouse Brain Atlas for genes differentially expressed along the rostrocaudal axis of the brainstem, identifying 36 genes from diverse functional families expressed in the LLN.ResultsAvailable information in the databases indicated that 7 of these 36 genes are either associated with or potentially related to hearing disorders.DiscussionIn conclusion, the LLN are characterized by specific molecular profiles that reflect their rostrocaudal organization into the three constituent nuclei. This molecular regionalization may be involved in the etiology of some hearing disorders, in accordance with previous functional studies of these genes.
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5
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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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6
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Company V, Andreu-Cervera A, Madrigal MP, Andrés B, Almagro-García F, Chédotal A, López-Bendito G, Martinez S, Echevarría D, Moreno-Bravo JA, Puelles E. Netrin 1-Mediated Role of the Substantia Nigra Pars Compacta and Ventral Tegmental Area in the Guidance of the Medial Habenular Axons. Front Cell Dev Biol 2021; 9:682067. [PMID: 34169076 PMCID: PMC8217627 DOI: 10.3389/fcell.2021.682067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/16/2021] [Indexed: 01/21/2023] Open
Abstract
The fasciculus retroflexus is an important fascicle that mediates reward-related behaviors and is associated with different psychiatric diseases. It is the main habenular efference and constitutes a link between forebrain regions, the midbrain, and the rostral hindbrain. The proper functional organization of habenular circuitry requires complex molecular programs to control the wiring of the habenula during development. However, the mechanisms guiding the habenular axons toward their targets remain mostly unknown. Here, we demonstrate the role of the mesodiencephalic dopaminergic neurons (substantia nigra pars compacta and ventral tegmental area) as an intermediate target for the correct medial habenular axons navigation along the anteroposterior axis. These neuronal populations are distributed along the anteroposterior trajectory of these axons in the mesodiencephalic basal plate. Using in vitro and in vivo experiments, we determined that this navigation is the result of netrin 1 attraction generated by the mesodiencephalic dopaminergic neurons. This attraction is mediated by the receptor deleted in colorectal cancer (DCC), which is strongly expressed in the medial habenular axons. The increment in our knowledge on the fasciculus retroflexus trajectory guidance mechanisms opens the possibility of analyzing if its alteration in mental health patients could account for some of their symptoms.
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Affiliation(s)
- Verónica Company
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Abraham Andreu-Cervera
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - M Pilar Madrigal
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Belén Andrés
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | | | - Alain Chédotal
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Salvador Martinez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Diego Echevarría
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Juan A Moreno-Bravo
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Eduardo Puelles
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
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7
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López-González L, Alonso A, García-Calero E, de Puelles E, Puelles L. Tangential Intrahypothalamic Migration of the Mouse Ventral Premamillary Nucleus and Fgf8 Signaling. Front Cell Dev Biol 2021; 9:676121. [PMID: 34095148 PMCID: PMC8170039 DOI: 10.3389/fcell.2021.676121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/15/2021] [Indexed: 02/02/2023] Open
Abstract
The tuberal hypothalamic ventral premamillary nucleus (VPM) described in mammals links olfactory and metabolic cues with mating behavior and is involved in the onset of puberty. We offer here descriptive and experimental evidence on a migratory phase in the development of this structure in mice at E12.5–E13.5. Its cells originate at the retromamillary area (RM) and then migrate tangentially rostralward, eschewing the mamillary body, and crossing the molecularly distinct perimamillary band, until they reach a definitive relatively superficial ventral tuberal location. Corroborating recent transcriptomic studies reporting a variety of adult glutamatergic cell types in the VPM, and different projections in the adult, we found that part of this population heterogeneity emerges already early in development, during tangential migration, in the form of differential gene expression properties of at least 2–3 mixed populations possibly derived from subtly different parts of the RM. These partly distribute differentially in the core and shell parts of the final VPM. Since there is a neighboring acroterminal source of Fgf8, and Fgfr2 is expressed at the early RM, we evaluated a possible influence of Fgf8 signal on VPM development using hypomorphic Fgf8neo/null embryos. These results suggested a trophic role of Fgf8 on RM and all cells migrating tangentially out of this area (VPM and the subthalamic nucleus), leading in hypomorphs to reduced cellularity after E15.5 without alteration of the migrations proper.
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Affiliation(s)
- Lara López-González
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Antonia Alonso
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Elena García-Calero
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Eduardo de Puelles
- Instituto de Neurociencias de Alicante, CSIC, Universidad Miguel Hernández, Alicante, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
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8
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García-Guillén IM, Alonso A, Puelles L, Marín F, Aroca P. Multiple Regionalized Genes and Their Putative Networks in the Interpeduncular Nucleus Suggest Complex Mechanisms of Neuron Development and Axon Guidance. Front Neuroanat 2021; 15:643320. [PMID: 33664652 PMCID: PMC7921722 DOI: 10.3389/fnana.2021.643320] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 01/26/2021] [Indexed: 12/27/2022] Open
Abstract
The interpeduncular nucleus (IPN) is a highly conserved limbic structure in the vertebrate brain, located in the isthmus and rhombomere 1. It is formed by various populations that migrate from different sites to the distinct domains within the IPN: the prodromal, rostral interpeduncular, and caudal interpeduncular nuclei. The aim here was to identify genes that are differentially expressed across these domains, characterizing their putative functional roles and interactions. To this end, we screened the 2,038 genes in the Allen Developing Mouse Brain Atlas database expressed at E18.5 and we identified 135 genes expressed within the IPN. The functional analysis of these genes highlighted an overrepresentation of gene families related to neuron development, cell morphogenesis and axon guidance. The interactome analysis within each IPN domain yielded specific networks that mainly involve members of the ephrin/Eph and Cadherin families, transcription factors and molecules related to synaptic neurotransmission. These results bring to light specific mechanisms that might participate in the formation, molecular regionalization, axon guidance and connectivity of the different IPN domains. This genoarchitectonic model of the IPN enables data on gene expression and interactions to be integrated and interpreted, providing a basis for the further study of the connectivity and function of this poorly understood nuclear complex under both normal and pathological conditions.
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Affiliation(s)
- Isabel M García-Guillén
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia and IMIB-Arrixaca, Murcia, Spain
| | - Antonia Alonso
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia and IMIB-Arrixaca, Murcia, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia and IMIB-Arrixaca, Murcia, Spain
| | - Faustino Marín
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia and IMIB-Arrixaca, Murcia, Spain
| | - Pilar Aroca
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia and IMIB-Arrixaca, Murcia, Spain
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9
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Guajardo HM, Hatini PG, Commons KG. The mouse dorsal raphe nucleus as understood by temporal Fgf8 lineage analysis. J Comp Neurol 2020; 529:2042-2054. [PMID: 33219573 DOI: 10.1002/cne.25071] [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: 06/24/2020] [Revised: 10/23/2020] [Accepted: 11/10/2020] [Indexed: 11/09/2022]
Abstract
Fgf8 is expressed transiently during embryogenesis at the midbrain-hindbrain border, an area that gives rise to a variety of neuronal populations including the dorsal raphe (DR) nucleus. Using an inducible Fgf8-cre allele, we identified the populations of neurons defined by Fgf8 lineage at different stages of development. When Fgf8-cre expression is induced at embryonic day 7.5 (T-E7.5), in the adult the entire DR and part of the median raphe (MnR) have Fgf8 lineage. When induced at later timepoints, Fgf8 lineage progressively ebbs from the caudal and ventral aspect of this domain, particularly on the midline. Successively excluded from Fgf8- lineage at T-E9.5 are serotonin neurons in the MnR and caudal-intrafascicular DR, followed at T-E11.5 by ventral-middle and caudal-dorsal DR. The last to show Fgf8 lineage are those serotonin neurons in the lateral wings and those at the rostral-dorsal pole of DR nucleus. Thus, the temporal succession of Fgf8 lineage correlates with organizational features of serotonin neurons in these nuclei.
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Affiliation(s)
- Herminio M Guajardo
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital and Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA
| | - Paul G Hatini
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital and Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA
| | - Kathryn G Commons
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital and Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA
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10
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García-Guillén IM, Alonso A, Morales-Delgado N, Andrés B, Puelles L, López-Bendito G, Marín F, Aroca P. Netrin-1/DCC Signaling Differentially Regulates the Migration of Pax7, Nkx6.1, Irx2, Otp, and Otx2 Cell Populations in the Developing Interpeduncular Nucleus. Front Cell Dev Biol 2020; 8:588851. [PMID: 33195252 PMCID: PMC7606981 DOI: 10.3389/fcell.2020.588851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/30/2020] [Indexed: 12/27/2022] Open
Abstract
The interpeduncular nucleus (IPN) is a hindbrain structure formed by three main subdivisions, the prodromal (Pro) domain located at the isthmus (Ist), and the rostral and caudal interpeduncular domains (IPR, IPC) within rhombomere 1 (r1). Various cell populations can be detected in the IPN through the expression of the Nkx6.1, Otp, Otx2, Pax7, and/or Irx2 transcription factors. These cell populations follow independent dorsoventral tangential and radial migratory routes targeting the ventral paramedian region of Ist and r1. Here we set out to examine the influence of the Netrin-1/DCC pathway on these migrations, since it is known to regulate other processes of neuronal migration in the brain. To this end, we analyzed IPN development in late gestational wild-type and DCC-/- mice, using mainly in situ hybridization (ISH) to identify the cells expressing each of the aforementioned genes. We found that the migration of Nkx6.1 + and Irx2 + cells into the Pro domain was strongly disrupted by the loss of DCC, as occurred with the migration of Pax7 +, Irx2 +, and Otp + cells that would normally form the IPR. In addition, there was mild impairment of the migration of the Pax7 + and Otx2 + cells that form the IPC. These results demonstrate that the Netrin-1/DCC signaling pathway is involved in the migration of most of the IPN populations, mainly affecting those of the Pro and IPR domains of this nucleus. There are psychiatric disorders that involve the medial habenula (mHb)-IPN system, so that this experimental model could provide a basis to study their neurodevelopmental etiology.
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Affiliation(s)
- Isabel M García-Guillén
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Antonia Alonso
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Nicanor Morales-Delgado
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain.,Department of Histology and Anatomy, School of Medicine, Miguel Hernández University, Alicante, Spain
| | - Belén Andrés
- Instituto de Neurociencias de Alicante, CSIC, Universidad Miguel Hernández, Alicante, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | | | - Faustino Marín
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
| | - Pilar Aroca
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain.,Biomedical Research Institute of Murcia (IMIB-Arrixaca), Murcia, Spain
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11
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Ádám Á, Kemecsei R, Company V, Murcia-Ramón R, Juarez I, Gerecsei LI, Zachar G, Echevarría D, Puelles E, Martínez S, Csillag A. Gestational Exposure to Sodium Valproate Disrupts Fasciculation of the Mesotelencephalic Dopaminergic Tract, With a Selective Reduction of Dopaminergic Output From the Ventral Tegmental Area. Front Neuroanat 2020; 14:29. [PMID: 32581730 PMCID: PMC7290005 DOI: 10.3389/fnana.2020.00029] [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: 02/14/2020] [Accepted: 05/11/2020] [Indexed: 01/14/2023] Open
Abstract
Gestational exposure to valproic acid (VPA) is known to cause behavioral deficits of sociability, matching similar alterations in human autism spectrum disorder (ASD). Available data are scarce on the neuromorphological changes in VPA-exposed animals. Here, we focused on alterations of the dopaminergic system, which is implicated in motivation and reward, with relevance to social cohesion. Whole brains from 7-day-old mice born to mothers given a single injection of VPA (400 mg/kg b.wt.) on E13.5 were immunostained against tyrosine hydroxylase (TH). They were scanned using the iDISCO method with a laser light-sheet microscope, and the reconstructed images were analyzed in 3D for quantitative morphometry. A marked reduction of mesotelencephalic (MT) axonal fascicles together with a widening of the MT tract were observed in VPA treated mice, while other major brain tracts appeared anatomically intact. We also found a reduction in the abundance of dopaminergic ventral tegmental (VTA) neurons, accompanied by diminished tissue level of DA in ventrobasal telencephalic regions (including the nucleus accumbens (NAc), olfactory tubercle, BST, substantia innominata). Such a reduction of DA was not observed in the non-limbic caudate-putamen. Conversely, the abundance of TH+ cells in the substantia nigra (SN) was increased, presumably due to a compensatory mechanism or to an altered distribution of TH+ neurons occupying the SN and the VTA. The findings suggest that defasciculation of the MT tract and neuronal loss in VTA, followed by diminished dopaminergic input to the ventrobasal telencephalon at a critical time point of embryonic development (E13-E14) may hinder the patterning of certain brain centers underlying decision making and sociability.
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Affiliation(s)
- Ágota Ádám
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Róbert Kemecsei
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Verónica Company
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - Raquel Murcia-Ramón
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - Iris Juarez
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - László I Gerecsei
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergely Zachar
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Diego Echevarría
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - Eduardo Puelles
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - Salvador Martínez
- Institute of Neuroscience (UMH-CSIC), University of Miguel Hernández, Alicante, Spain
| | - András Csillag
- Department of Anatomy, Histology, and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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12
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Developmental Requirement of Homeoprotein Otx2 for Specific Habenulo-Interpeduncular Subcircuits. J Neurosci 2018; 39:1005-1019. [PMID: 30593496 DOI: 10.1523/jneurosci.1818-18.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/06/2018] [Accepted: 12/16/2018] [Indexed: 01/11/2023] Open
Abstract
The habenulo-interpeduncular system (HIPS) is now recognized as a critical circuit modulating aversion, reward, and social behavior. There is evidence that dysfunction of this circuit leads to psychiatric disorders. Because psychiatric diseases may originate in developmental abnormalities, it is crucial to investigate the developmental mechanisms controlling the formation of the HIPS. Thus far, this issue has been the focus of limited studies. Here, we explored the developmental processes underlying the formation of the medial habenula (MHb) and its unique output, the interpeduncular nucleus (IPN), in mice independently of their gender. We report that the Otx2 homeobox gene is essential for the proper development of both structures. We show that MHb and IPN neurons require Otx2 at different developmental stages and, in both cases, Otx2 deletion leads to disruption of HIPS subcircuits. Finally, we show that Otx2+ neurons tend to be preferentially interconnected. This study reveals that synaptically connected components of the HIPS, despite radically different developmental strategies, share high sensitivity to Otx2 expression.SIGNIFICANCE STATEMENT Brain reward circuits are highly complex and still poorly understood. In particular, it is important to understand how these circuits form as many psychiatric diseases may arise from their abnormal development. This work shows that Otx2, a critical evolutionary conserved gene implicated in brain development and a predisposing factor for psychiatric diseases, is required for the formation of the habenulo-interpeduncular system (HIPS), an important component of the reward circuit. Otx2 deletion affects multiple processes such as proliferation and migration of HIPS neurons. Furthermore, neurons expressing Otx2 are preferentially interconnected. Therefore, Otx2 expression may represent a code that specifies the connectivity of functional subunits of the HIPS. Importantly, the Otx2 conditional knock-out animals used in this study might represent a new genetic model of psychiatric diseases.
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13
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Puelles L, Tvrdik P, Martínez-de-la-torre M. The Postmigratory Alar Topography of Visceral Cranial Nerve Efferents Challenges the Classical Model of Hindbrain Columns. Anat Rec (Hoboken) 2018; 302:485-504. [DOI: 10.1002/ar.23830] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Luis Puelles
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, School of Medicine; University of Murcia; Murcia 30071 Spain
| | - Petr Tvrdik
- Department of Neurosurgery-Physiology; University of Utah; Salt Lake City, Utah 84112
| | - Margaret Martínez-de-la-torre
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, School of Medicine; University of Murcia; Murcia 30071 Spain
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14
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Plummer NW, Scappini EL, Smith KG, Tucker CJ, Jensen P. Two Subpopulations of Noradrenergic Neurons in the Locus Coeruleus Complex Distinguished by Expression of the Dorsal Neural Tube Marker Pax7. Front Neuroanat 2017; 11:60. [PMID: 28775681 PMCID: PMC5518464 DOI: 10.3389/fnana.2017.00060] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/07/2017] [Indexed: 01/05/2023] Open
Abstract
Central noradrenergic neurons, collectively defined by synthesis of the neurotransmitter norepinephrine, are a diverse collection of cells in the hindbrain, differing in their anatomy, physiological and behavioral functions, and susceptibility to disease and environmental insult. To investigate the developmental basis of this heterogeneity, we have used an intersectional genetic fate mapping strategy in mice to study the dorsoventral origins of the En1-derived locus coeruleus (LC) complex which encompasses virtually all of the anatomically defined LC proper, as well as a portion of the A7 and subcoeruleus (SubC) noradrenergic nuclei. We show that the noradrenergic neurons of the LC complex originate in two different territories of the En1 expression domain in the embryonic hindbrain. Consistent with prior studies, we confirm that the majority of the LC proper arises from the alar plate, the dorsal domain of the neural tube, as defined by expression of Pax7Cre. In addition, our analysis shows that a large proportion of the En1-derived A7 and SubC nuclei also originate in the Pax7Cre-defined alar plate. Surprisingly, however, we identify a smaller subpopulation of the LC complex that arises from outside the Pax7Cre expression domain. We characterize the distribution of these neurons within the LC complex, their cell morphology, and their axonal projection pattern. Compared to the broader LC complex, the newly identified Pax7Cre-negative noradrenergic subpopulation has very sparse projections to thalamic nuclei, suggestive of distinct functions. This developmental genetic analysis opens new avenues of investigation into the functional diversity of the LC complex.
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Affiliation(s)
- Nicholas W Plummer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, United States Department of Health and Human ServicesDurham, NC, United States
| | - Erica L Scappini
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, United States Department of Health and Human ServicesDurham, NC, United States
| | - Kathleen G Smith
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, United States Department of Health and Human ServicesDurham, NC, United States
| | - Charles J Tucker
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, United States Department of Health and Human ServicesDurham, NC, United States
| | - Patricia Jensen
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, United States Department of Health and Human ServicesDurham, NC, United States
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15
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Watson C, Shimogori T, Puelles L. Mouse Fgf8-Cre-LacZ lineage analysis defines the territory of the postnatal mammalian isthmus. J Comp Neurol 2017; 525:2782-2799. [PMID: 28510270 DOI: 10.1002/cne.24242] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/19/2017] [Accepted: 05/05/2017] [Indexed: 12/17/2022]
Abstract
The isthmus is recognized as the most rostral segment of the hindbrain in non-mammalian vertebrates. In mammalian embryos, transient Fgf8 expression defines the developing isthmic region, lying between the midbrain and the first rhombomere, but there has been uncertainty about the existence of a distinct isthmic segment in postnatal mammals. We attempted to find if the region of early embryonic Fgf8 expression (which is considered to involve the entire extent of the prospective isthmus initially) might help to identify the boundaries of the isthmus in postnatal animals. By creating an Fgf8-Cre-LacZ lineage in mice, we were able to show that Fgf8-Cre reporter expression in postnatal mice is present in the same nuclei that characterize the isthmic region in birds. The 'signature' isthmic structures in birds include the trochlear nucleus, the dorsal raphe nucleus, the microcellular tegmental nuclei, the pedunculotegmental nucleus, the vermis of the cerebellum, rostral parts of the parabrachial complex and locus coeruleus, and the caudal parts of the substantia nigra and VTA. We found that all of these structures were labeled with the Fgf8-Cre reporter in the mouse brain, and we conclude that the isthmus is a distinct segment of the mammalian brain lying caudal to the midbrain and rostral to rhombomere 1 of the hindbrain.
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Affiliation(s)
| | | | - Luis Puelles
- Faculty of Medicine and IMIB-Arrixaca, University of Murcia, Murcia, Spain
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16
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Martinez-de-la-Torre M, Lambertos A, Peñafiel R, Puelles L. An exercise in brain genoarchitectonics: Analysis of AZIN2-Lacz expressing neuronal populations in the mouse hindbrain. J Neurosci Res 2017; 96:1490-1517. [PMID: 28467636 DOI: 10.1002/jnr.24053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/08/2016] [Accepted: 02/27/2017] [Indexed: 02/05/2023]
Abstract
We examined in detail the distribution of AZIN2 (antizyme inhibitor 2) expression in the adult mouse hindbrain and neighboring spinal cord. AZIN2, similar to previously known AZIN1, is a recently-discovered, a functional paralog of ornithine decarboxylase (ODC). Due to their structural similarity to ODC, both AZIN1 and AZIN2 counteract the inhibitory action of 3 known antizymes (AZ1-3) on the ODC synthesis of polyamines, thus increasing intracytoplasmic levels of polyamines. AZIN2 is strongly, but heterogeneously, expressed in the brain. Our study uses a mouse line carrying an AZIN2-LacZ construct, and, in our topographic analysis of AZIN2-positive structures, we intend to share new knowledge about the rhombomeric segmentation of the hindbrain (a function of Hox paralogs and other genes). The observed labeled cell populations predominantly coincide with known cholinergic and glutamatergic cells, but occasionally also correspond to GABAergic, and possibly glycinergic cells. Some imperfectly known hindbrain populations stood out in unprecedented detail, and some axonal tracts were also differentially stained. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Ana Lambertos
- Dept. Biochemistry and Molecular Biology, Faculty of Medicine, University of Murcia and IMIB, Murcia, 30071, Spain
| | - Rafael Peñafiel
- Dept. Biochemistry and Molecular Biology, Faculty of Medicine, University of Murcia and IMIB, Murcia, 30071, Spain
| | - Luis Puelles
- Dept.Human Anatomy, Faculty of Medicine, University of Murcia and IMIB, Murcia, 30071, Spain
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17
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Nuclear derivatives and axonal projections originating from rhombomere 4 in the mouse hindbrain. Brain Struct Funct 2017; 222:3509-3542. [PMID: 28470551 PMCID: PMC5676809 DOI: 10.1007/s00429-017-1416-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/27/2017] [Indexed: 01/13/2023]
Abstract
The r4-derived territory is located in the pontine region of the brainstem, forming a wedge-shaped slice that broadens from the choroidal roof to the ventral midline. R4-derived neuronal populations migrate radially inside and tangentially outside this rhombomere, forming nuclei of the sensorimotor auditory, vestibular, trigeminal and reticular systems. R4-derived fibre tracts contribute to the lateral lemniscus, the trigeminothalamic tracts, the medial tegmental tract and the medial forebrain bundle, which variously project to the midbrain, thalamus, hypothalamus and telencephalon. Other tracts such as the trigeminocerebellar and vestibulocerebellar tracts reach the cerebellum, while the medial and lateral vestibulospinal tracts, and the reticulospinal and trigeminal oro-spinal tracts extend into the spinal cord. Many r4-derived fibres are crossed; they decussate to the contralateral side traversing the midline through the cerebellar, collicular and intercollicular commissures, as well as the supraoptic decussation. Moreover, some fibres enter into the posterior and anterior commissures and some terminals reach the septum. Overall, this study provides an overview of all r4 neuronal populations and axonal tracts from their embryonic origin to the adult final location and target.
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18
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Identification of proliferative progenitors associated with prominent postnatal growth of the pons. Nat Commun 2016; 7:11628. [PMID: 27188978 PMCID: PMC4873968 DOI: 10.1038/ncomms11628] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 04/14/2016] [Indexed: 01/28/2023] Open
Abstract
The pons controls crucial sensorimotor and autonomic functions. In humans, it grows sixfold postnatally and is a site of paediatric gliomas; however, the mechanisms of pontine growth remain poorly understood. We show that the murine pons quadruples in volume postnatally; growth is fastest during postnatal days 0–4 (P0–P4), preceding most myelination. We identify three postnatal proliferative compartments: ventricular, midline and parenchymal. We find no evidence of postnatal neurogenesis in the pons, but each progenitor compartment produces new astroglia and oligodendroglia; the latter expand 10- to 18-fold postnatally, and are derived mostly from the parenchyma. Nearly all parenchymal progenitors at P4 are Sox2+Olig2+, but by P8 a Sox2− subpopulation emerges, suggesting a lineage progression from Sox2+ ‘early' to Sox2− ‘late' oligodendrocyte progenitor. Fate mapping reveals that >90% of adult oligodendrocytes derive from P2–P3 Sox2+ progenitors. These results demonstrate the importance of postnatal Sox2+Olig2+ progenitors in pontine growth and oligodendrogenesis. Postnatal growth of the pons is not well characterized. Here the authors show that growth of the murine pons is fastest during postnatal day 0–4, a period preceding myelination, and is primarily driven by an expansion of the oligodendrocyte population that derive from Sox2+Olig2+ progenitors.
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19
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Madrigal MP, Moreno-Bravo JA, Martínez-López JE, Martínez S, Puelles E. Mesencephalic origin of the rostral Substantia nigra pars reticulata. Brain Struct Funct 2016; 221:1403-12. [PMID: 25579066 PMCID: PMC4819793 DOI: 10.1007/s00429-014-0980-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/24/2014] [Indexed: 12/03/2022]
Abstract
In embryonic development, the neurons that will constitute a heterogeneous nucleus may have distinct origins. The different components of these populations reach their final location by radial and tangential migrations. The Substantia nigra pars reticulata (SNR) presents a high level of neuronal heterogeneity. It is composed by GABAergic neurons located in the mes-diencephalic basal plate. These inhibitory neurons usually display tangential migrations and it has been already described that the caudal SNR is colonized tangentially from rhombomere 1. Our aim is to unveil the origin of the rostral SNR. We have localized a Nkx6.2 positive ventricular domain located in the alar midbrain. Nkx6.2 derivatives' fate map analysis showed mainly a rostral colonization of this GABAergic neuronal population. We confirmed the mesencephalic origin by the expression of Six3. Both transcription factors are sequentially expressed along the differentiation of these neurons. We demonstrated the origin of the rostral SNR; our data allowed us to postulate that this nucleus is composed by two neuronal populations distributed in opposite gradients with different origins, one from rhombomere 1, caudal to rostral, and the other from the midbrain, rostral to caudal. We can conclude that the SNR has multiple origins and follows complex mechanisms of specification and migration. Our results support vital information for the study of genetic modifications in these extremely complex processes that result in devastating behavioral alterations and predisposition to psychiatric diseases. Understanding the development, molecular identity and functional characteristics of these diverse neuronal populations might lead to better diagnosis and treatment of several forms of neurological and psychiatric disease.
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Affiliation(s)
- M Pilar Madrigal
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, Sant Joan d'Alacant, Alicante, Spain
| | - Juan A Moreno-Bravo
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, Sant Joan d'Alacant, Alicante, Spain
| | - Jesús E Martínez-López
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, Sant Joan d'Alacant, Alicante, Spain
| | - Salvador Martínez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, Sant Joan d'Alacant, Alicante, Spain
- Instituto Murciano de Investigación Biomédica IMIB-Arrixaca, E30120, Murcia, Spain
| | - Eduardo Puelles
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, Sant Joan d'Alacant, Alicante, Spain.
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20
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Moreno-Bravo JA, Martinez-Lopez JE, Madrigal MP, Kim M, Mastick GS, Lopez-Bendito G, Martinez S, Puelles E. Developmental guidance of the retroflex tract at its bending point involves Robo1-Slit2-mediated floor plate repulsion. Brain Struct Funct 2016; 221:665-78. [PMID: 25366972 PMCID: PMC4485949 DOI: 10.1007/s00429-014-0932-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/24/2014] [Indexed: 10/24/2022]
Abstract
The retroflex tract contains medial habenula efferents that target the hindbrain interpeduncular complex and surrounding areas. This tract displays a singular course. Initially, habenular axons extend ventralwards in front of the pretectum until they reach the basal plate. Next, they avoid crossing the local floor plate, sharply changing course caudalwards (the retroflexion alluded by the tract name) and navigate strictly antero-posteriorly across basal pretectum, midbrain and isthmus. Once they reach rhombomere 1, the habenular axons criss-cross the floor plate several times within the interpeduncular nuclear complex as they innervate it. Here we described the timing and details of growth phenomena as these axons navigate to their target. The first dorsoventral course apparently obeys Ntn1 attraction. We checked the role of local floor plate signaling in the decision to avoid the thalamic floor plate and bend caudalwards. Analyzing the altered floor and basal plates of Gli2 knockout mice, we found a contralateral projection of most habenular axons, plus ulterior bizarre navigation rostralwards. This crossing phenotype was due to a reduced expression of Slit repulsive cues, suggesting involvement of the floor-derived Robo-Slit system in the normal guidance of this tract. Using Slit and Robo mutant mice, open neural tube and co-culture assays, we determined that Robo1-Slit2 interaction is specifically required for impeding that medial habenular axons cross the thalamic floor plate. This pathfinding mechanism is essential to establish the functionally important habenulo-interpeduncular connection.
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Affiliation(s)
- Juan A Moreno-Bravo
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Jesus E Martinez-Lopez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain
| | - M Pilar Madrigal
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Minkyung Kim
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | - Grant S Mastick
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | - Guillermina Lopez-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Salvador Martinez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain
- Instituto Murciano de Investigación Biomédica IMIB-Arrixaca, Murcia, Spain
| | - Eduardo Puelles
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain.
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21
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Ryczko D, Auclair F, Cabelguen JM, Dubuc R. The mesencephalic locomotor region sends a bilateral glutamatergic drive to hindbrain reticulospinal neurons in a tetrapod. J Comp Neurol 2015; 524:1361-83. [PMID: 26470600 PMCID: PMC5019149 DOI: 10.1002/cne.23911] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/01/2015] [Accepted: 10/07/2015] [Indexed: 01/09/2023]
Abstract
In vertebrates, stimulation of the mesencephalic locomotor region (MLR) on one side evokes symmetrical locomotor movements on both sides. How this occurs was previously examined in detail in a swimmer using body undulations (lamprey), but in tetrapods the downstream projections from the MLR to brainstem neurons are not fully understood. Here we examined the brainstem circuits from the MLR to identified reticulospinal neurons in the salamander Notophthalmus viridescens. Using neural tracing, we show that the MLR sends bilateral projections to the middle reticular nucleus (mRN, rostral hindbrain) and the inferior reticular nucleus (iRN, caudal hindbrain). Ca2+ imaging coupled to electrophysiology in in vitro isolated brains revealed very similar responses in reticulospinal neurons on both sides to a unilateral MLR stimulation. As the strength of MLR stimulation was increased, the responses increased in size in reticulospinal neurons of the mRN and iRN, but the responses in the iRN were smaller. Bath‐application or local microinjections of glutamatergic antagonists markedly reduced reticulospinal neuron responses, indicating that the MLR sends glutamatergic inputs to reticulospinal neurons. In addition, reticulospinal cells responded to glutamate microinjections and the size of the responses paralleled the amount of glutamate microinjected. Immunofluorescence coupled with anatomical tracing confirmed the presence of glutamatergic projections from the MLR to reticulospinal neurons. Overall, we show that the brainstem circuits activated by the MLR in the salamander are organized similarly to those previously described in lampreys, indicating that the anatomo‐physiological features of the locomotor drive are well conserved in vertebrates. J. Comp. Neurol. 524:1361–1383, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Francois Auclair
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Marie Cabelguen
- INSERM U862 - Neurocentre Magendie, Motor System Diseases Team, Bordeaux Cedex, France
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Québec, Canada
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22
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Martinez-Ferre A, Lloret-Quesada C, Prakash N, Wurst W, Rubenstein JLR, Martinez S. Fgf15 regulates thalamic development by controlling the expression of proneural genes. Brain Struct Funct 2015; 221:3095-109. [PMID: 26311466 DOI: 10.1007/s00429-015-1089-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 07/21/2015] [Indexed: 01/01/2023]
Abstract
The establishment of the brain structural complexity requires a precisely orchestrated interplay between extrinsic and intrinsic signals modulating cellular mechanisms to guide neuronal differentiation. However, little is known about the nature of these signals in the diencephalon, a complex brain region that processes and relays sensory and motor information to and from the cerebral cortex and subcortical structures. Morphogenetic signals from brain organizers regulate histogenetic processes such as cellular proliferation, migration, and differentiation. Sonic hedgehog (Shh) in the key signal of the ZLI, identified as the diencephalic organizer. Fgf15, the mouse gene orthologous of human, chick, and zebrafish Fgf19, is induced by Shh signal and expressed in the diencephalic alar plate progenitors during histogenetic developmental stages. This work investigates the role of Fgf15 signal in diencephalic development. In the absence of Fgf15, the complementary expression pattern of proneural genes: Ascl1 and Nng2, is disrupted and the GABAergic thalamic cells do not differentiate; in addition dorsal thalamic progenitors failed to exit from the mitotic cycle and to differentiate into neurons. Therefore, our findings indicate that Fgf15 is the Shh downstream signal to control thalamic regionalization, neurogenesis, and neuronal differentiation by regulating the expression and mutual segregation of neurogenic and proneural regulatory genes.
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Affiliation(s)
- Almudena Martinez-Ferre
- Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), University of Murcia, 30120, El Palmar, Murcia, Spain
| | - Cosme Lloret-Quesada
- Institute of Neurosciences, Miguel Hernández University, Spanish National Research Council, San Juan Campus, 03550, Sant Joan d'Alacant, Alicante, Spain
| | - Nilima Prakash
- Institute of Developmental Genetics, Helmholtz Centre Munich, German Research Centre for Environmental Health (GmbH), Technical University Munich, Ingolstaedter Landstr. 1, 85764, Neuherberg, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Centre Munich, German Research Centre for Environmental Health (GmbH), Technical University Munich, Ingolstaedter Landstr. 1, 85764, Neuherberg, Germany
| | - John L R Rubenstein
- Department of Psychiatry, Nina Ireland Laboratory of Developmental Neurobiology, University of California San Francisco, San Francisco, CA, USA
| | - Salvador Martinez
- Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), University of Murcia, 30120, El Palmar, Murcia, Spain. .,Institute of Neurosciences, Miguel Hernández University, Spanish National Research Council, San Juan Campus, 03550, Sant Joan d'Alacant, Alicante, Spain. .,Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Valencia, Spain.
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23
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Developmental alterations of the septohippocampal cholinergic projection in a lissencephalic mouse model. Exp Neurol 2015; 271:215-27. [PMID: 26079645 DOI: 10.1016/j.expneurol.2015.06.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 05/19/2015] [Accepted: 06/12/2015] [Indexed: 11/22/2022]
Abstract
LIS1 is one of principal genes related with Type I lissencephaly, a severe human brain malformation characterized by abnormal neuronal migration in the cortex. The LIS1 gene encodes a brain-specific 45kDa non-catalytic subunit of platelet-activating factor (PAF) acetylhydrolase-1b (PAFAH1b), an enzyme that inactivates the PAF. We have studied the role of Lis1 using a Lis1/sLis1 murine model, which has deleted the first coding exon from Lis1 gene. Homozygous mice are not viable but heterozygous have shown a delayed corticogenesis and neuronal dysplasia, with enhanced cortical excitability. Lis1/sLis1 embryos also exhibited a delay of cortical innervation by the thalamocortical fibers. We have explored in Lis1/sLis1 mice anomalies in forebrain cholinergic neuron development, which migrate from pallium to subpallium, and functionally represent the main cholinergic input to the cerebral cortex, modulating cortical activity and facilitating attention, learning, and memory. We hypothesized that primary migration anomalies and/or disorganized cortex could affect cholinergic projections from the basal forebrain and septum in Lis1/sLis1 mouse. To accomplish our objective we have first studied basal forebrain neurons in Lis1/sLis1 mice during development, and described structural and hodological differences between wild-type and Lis1/sLis1 embryos. In addition, septohippocampal projections showed altered development in mutant embryos. Basal forebrain abnormalities could contribute to hippocampal excitability anomalies secondary to Lis1 mutations and may explain the cognitive symptoms associated to cortical displasia-related mental diseases and epileptogenic syndromes.
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24
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Morphogenesis of the cerebellum and cerebellum-related structures in the shark Scyliorhinus canicula: insights on the ground pattern of the cerebellar ontogeny. Brain Struct Funct 2015; 221:1691-717. [DOI: 10.1007/s00429-015-0998-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/28/2015] [Indexed: 10/24/2022]
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25
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Willaredt MA, Schlüter T, Nothwang HG. The gene regulatory networks underlying formation of the auditory hindbrain. Cell Mol Life Sci 2015; 72:519-535. [PMID: 25332098 PMCID: PMC11113740 DOI: 10.1007/s00018-014-1759-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/24/2014] [Accepted: 10/09/2014] [Indexed: 01/28/2023]
Abstract
Development and evolution of auditory hindbrain nuclei are two major unsolved issues in hearing research. Recent characterization of transgenic mice identified the rhombomeric origins of mammalian auditory nuclei and unraveled genes involved in their formation. Here, we provide an overview on these data by assembling them into rhombomere-specific gene regulatory networks (GRNs), as they underlie developmental and evolutionary processes. To explore evolutionary mechanisms, we compare the GRNs operating in the mammalian auditory hindbrain with data available from the inner ear and other vertebrate groups. Finally, we propose that the availability of genomic sequences from all major vertebrate taxa and novel genetic techniques for non-model organisms provide an unprecedented opportunity to investigate development and evolution of the auditory hindbrain by comparative molecular approaches. The dissection of the molecular mechanisms leading to auditory structures will also provide an important framework for auditory processing disorders, a clinical problem difficult to tackle so far. These data will, therefore, foster basic and clinical hearing research alike.
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Affiliation(s)
- Marc A Willaredt
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
| | - Tina Schlüter
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
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26
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The emerging framework of mammalian auditory hindbrain development. Cell Tissue Res 2015; 361:33-48. [DOI: 10.1007/s00441-014-2110-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 12/22/2014] [Indexed: 02/06/2023]
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27
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Pose-Méndez S, Candal E, Mazan S, Rodríguez-Moldes I. Genoarchitecture of the rostral hindbrain of a shark: basis for understanding the emergence of the cerebellum at the agnathan–gnathostome transition. Brain Struct Funct 2015; 221:1321-35. [DOI: 10.1007/s00429-014-0973-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 12/17/2014] [Indexed: 12/14/2022]
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28
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Gilland E, Straka H, Wong TW, Baker R, Zottoli SJ. A hindbrain segmental scaffold specifying neuronal location in the adult goldfish, Carassius auratus. J Comp Neurol 2014; 522:2446-64. [PMID: 24452830 DOI: 10.1002/cne.23544] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 01/15/2014] [Accepted: 01/17/2014] [Indexed: 12/18/2022]
Abstract
The vertebrate hindbrain develops as a series of well-defined neuroepithelial segments or rhombomeres. While rhombomeres are visible in all vertebrate embryos, generally there is not any visible segmental anatomy in the brains of adults. Teleost fish are exceptional in retaining a rhombomeric pattern of reticulospinal neurons through embryonic, larval, and adult periods. We use this feature to map more precisely the segmental imprint in the reticular and motor basal hindbrain of adult goldfish. Analysis of serial sections cut in three planes and computer reconstructions of retrogradely labeled reticulospinal neurons yielded a segmental framework compatible with previous reports and more amenable to correlation with surrounding neuronal features. Cranial nerve motoneurons and octavolateral efferent neurons were aligned to the reticulospinal scaffold by mapping neurons immunopositive for choline acetyltransferase or retrogradely labeled from cranial nerve roots. The mapping corresponded well with the known ontogeny of these neurons and helps confirm the segmental territories defined by reticulospinal anatomy. Because both the reticulospinal and the motoneuronal segmental patterns persist in the hindbrain of adult goldfish, we hypothesize that a permanent "hindbrain framework" may be a general property that is retained in adult vertebrates. The establishment of a relationship between individual segments and neuronal phenotypes provides a convenient method for future studies that combine form, physiology, and function in adult vertebrates.
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Affiliation(s)
- E Gilland
- Department of Physiology and Neuroscience, New York University Medical Center, New York, New York, 10016; Marine Biological Laboratory, Woods Hole, Massachusetts, 02543; Department of Anatomy, Howard University College of Medicine, Washington, DC, 20059
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29
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Moreno N, Joven A, Morona R, Bandín S, López JM, González A. Conserved localization of Pax6 and Pax7 transcripts in the brain of representatives of sarcopterygian vertebrates during development supports homologous brain regionalization. Front Neuroanat 2014; 8:75. [PMID: 25147506 PMCID: PMC4123791 DOI: 10.3389/fnana.2014.00075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/21/2014] [Indexed: 11/20/2022] Open
Abstract
Many of the genes involved in brain patterning during development are highly conserved in vertebrates and similarities in their expression patterns help to recognize homologous cell types or brain regions. Among these genes, Pax6 and Pax7 are expressed in regionally restricted patterns in the brain and are essential for its development. In the present immunohistochemical study we analyzed the distribution of Pax6 and Pax7 cells in the brain of six representative species of tetrapods and lungfishes, the closest living relatives of tetrapods, at several developmental stages. The distribution patterns of these transcription factors were largely comparable across species. In all species only Pax6 was expressed in the telencephalon, including the olfactory bulbs, septum, striatum, and amygdaloid complex. In the diencephalon, Pax6 and Pax7 were distinct in the alar and basal parts, mainly in prosomeres 1 and 3. Pax7 specifically labeled cells in the optic tectum (superior colliculus) and Pax6, but not Pax7, cells were found in the tegmentum. Pax6 was found in most granule cells of the cerebellum and Pax7 labeling was detected in cells of the ventricular zone of the rostral alar plate and in migrated cells in the basal plate, including the griseum centrale and the interpeduncular nucleus. Caudally, Pax6 cells formed a column, whereas the ventricular zone of the alar plate expressed Pax7. Since the observed Pax6 and Pax7 expression patterns are largely conserved they can be used to identify subdivisions in the brain across vertebrates that are not clearly discernible with classical techniques.
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Affiliation(s)
- Nerea Moreno
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Alberto Joven
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Ruth Morona
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Sandra Bandín
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Jesús M López
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Agustín González
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
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30
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Ferent J, Traiffort E. Hedgehog: Multiple Paths for Multiple Roles in Shaping the Brain and Spinal Cord. Neuroscientist 2014; 21:356-71. [PMID: 24743306 DOI: 10.1177/1073858414531457] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Since the discovery of the segment polarity gene Hedgehog in Drosophila three decades ago, our knowledge of Hedgehog signaling pathway has considerably improved and paved the way to a wide field of investigations in the developing and adult central nervous system. Its peculiar transduction mechanism together with its implication in tissue patterning, neural stem cell biology, and neural tissue homeostasis make Hedgehog pathway of interest in a high number of normal or pathological contexts. Consistent with its role during brain development, misregulation of Hedgehog signaling is associated with congenital diseases and tumorigenic processes while its recruitment in damaged neural tissue may be part of the repairing process. This review focuses on the most recent data regarding the Hedgehog pathway in the developing and adult central nervous system and also its relevance as a therapeutic target in brain and spinal cord diseases.
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Affiliation(s)
- Julien Ferent
- IRCM, Molecular Biology of Neural Development, Montreal, Quebec, Canada
| | - Elisabeth Traiffort
- INSERM-Université Paris Sud, Neuroprotection and Neuroregeneration: Small Neuroactive Molecules UMR 788, Le Kremlin-Bicêtre, France
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31
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Di Bonito M, Glover JC, Studer M. Hox genes and region-specific sensorimotor circuit formation in the hindbrain and spinal cord. Dev Dyn 2013; 242:1348-68. [PMID: 23996673 DOI: 10.1002/dvdy.24055] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/29/2013] [Accepted: 08/29/2013] [Indexed: 01/17/2023] Open
Abstract
Homeobox (Hox) genes were originally discovered in the fruit fly Drosophila, where they function through a conserved homeodomain as transcriptional regulators to control embryonic morphogenesis. In vertebrates, 39 Hox genes have been identified and like their Drosophila counterparts they are organized within chromosomal clusters. Hox genes interact with various cofactors, such as the TALE homeodomain proteins, in recognition of consensus sequences within regulatory elements of their target genes. In vertebrates, Hox genes display spatially restricted patterns of expression within the developing hindbrain and spinal cord, and are considered crucial determinants of segmental identity and cell specification along the anterioposterior and dorsoventral axes of the embryo. Here, we review their later roles in the assembly of neuronal circuitry, in stereotypic neuronal migration, axon pathfinding, and topographic connectivity. Importantly, we will put some emphasis on how their early-segmented expression patterns can influence the formation of complex vital hindbrain and spinal cord circuitries.
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Affiliation(s)
- Maria Di Bonito
- University of Nice-Sophia Antipolis, F-06108, Nice, France; INSERM, iBV, UMR 1091, F-06108, Nice, France
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