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Yang X, Cheng B, Cheng S, Liu L, Pan C, Meng P, Li C, Chen Y, Zhang J, Zhang H, Zhang Z, Wen Y, Jia Y, Liu H, Zhang F. A genome-wide association study identifies candidate genes for sleep disturbances in depressed individuals. Hum Genomics 2024; 18:51. [PMID: 38778419 PMCID: PMC11110369 DOI: 10.1186/s40246-024-00609-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 04/15/2024] [Indexed: 05/25/2024] Open
Abstract
OBJECTIVE This study aimed to identify candidate loci and genes related to sleep disturbances in depressed individuals and clarify the co-occurrence of sleep disturbances and depression from the genetic perspective. METHODS The study subjects (including 58,256 self-reported depressed individuals and 6,576 participants with PHQ-9 score ≥ 10, respectively) were collected from the UK Biobank, which were determined based on the Patient Health Questionnaire (PHQ-9) and self-reported depression status, respectively. Sleep related traits included chronotype, insomnia, snoring and daytime dozing. Genome-wide association studies (GWASs) of sleep related traits in depressed individuals were conducted by PLINK 2.0 adjusting age, sex, Townsend deprivation index and 10 principal components as covariates. The CAUSALdb database was used to explore the mental traits associated with the candidate genes identified by the GWAS. RESULTS GWAS detected 15 loci significantly associated with chronotype in the subjects with self-reported depression, such as rs12736689 at RNASEL (P = 1.00 × 10- 09), rs509476 at RGS16 (P = 1.58 × 10- 09) and rs1006751 at RFX4 (P = 1.54 × 10- 08). 9 candidate loci were identified in the subjects with PHQ-9 ≥ 10, of which 2 loci were associated with insomnia such as rs115379847 at EVC2 (P = 3.50 × 10- 08), and 7 loci were associated with daytime dozing, such as rs140876133 at SMYD3 (P = 3.88 × 10- 08) and rs139156969 at ROBO2 (P = 3.58 × 10- 08). Multiple identified genes, such as RNASEL, RGS16, RFX4 and ROBO2 were reported to be associated with chronotype, depression or cognition in previous studies. CONCLUSION Our study identified several candidate genes related to sleep disturbances in depressed individuals, which provided new clues for understanding the biological mechanism underlying the co-occurrence of depression and sleep disorders.
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Affiliation(s)
- Xuena Yang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Bolun Cheng
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Shiqiang Cheng
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Li Liu
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Chuyu Pan
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Peilin Meng
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Chun'e Li
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Yujing Chen
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Jingxi Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Huijie Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Zhen Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Yan Wen
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Yumeng Jia
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Huan Liu
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Feng Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, China.
- Department of Psychiatry, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
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Riley B, Gould E, Lloyd J, Hallum LE, Vlajkovic S, Todd K, Freestone PS. Dopamine transmission in the tail striatum: Regional variation and contribution of dopamine clearance mechanisms. J Neurochem 2024; 168:251-268. [PMID: 38308566 DOI: 10.1111/jnc.16052] [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: 08/11/2023] [Revised: 12/05/2023] [Accepted: 01/05/2024] [Indexed: 02/05/2024]
Abstract
The striatum can be divided into four anatomically and functionally distinct domains: the dorsolateral, dorsomedial, ventral and the more recently identified caudolateral (tail) striatum. Dopamine transmission in these striatal domains underlies many important behaviours, yet little is known about this phenomenon in the tail striatum. Furthermore, the tail is divided anatomically into four divisions (dorsal, medial, intermediate and lateral) based on the profile of D1 and D2 dopamine receptor-expressing medium spiny neurons, something that is not seen elsewhere in the striatum. Considering this organisation, how dopamine transmission occurs in the tail striatum is of great interest. We recorded evoked dopamine release in the four tail divisions, with comparison to the dorsolateral striatum, using fast-scan cyclic voltammetry in rat brain slices. Contributions of clearance mechanisms were investigated using dopamine transporter knockout (DAT-KO) rats, pharmacological transporter inhibitors and dextran. Evoked dopamine release in all tail divisions was smaller in amplitude than in the dorsolateral striatum and, importantly, regional variation was observed: dorsolateral ≈ lateral > medial > dorsal ≈ intermediate. Release amplitudes in the lateral division were 300% of that in the intermediate division, which also exhibited uniquely slow peak dopamine clearance velocity. Dopamine clearance in the intermediate division was most dependent on DAT, and no alternative dopamine transporters investigated (organic cation transporter-3, norepinephrine transporter and serotonin transporter) contributed significantly to dopamine clearance in any tail division. Our findings confirm that the tail striatum is not only a distinct dopamine domain but also that each tail division has unique dopamine transmission characteristics. This supports that the divisions are not only anatomically but also functionally distinct. How this segregation relates to the overall function of the tail striatum, particularly the processing of multisensory information, is yet to be determined.
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Affiliation(s)
- Bronwyn Riley
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Emily Gould
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Jordan Lloyd
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Luke E Hallum
- Department of Mechanical and Mechatronics Engineering, University of Auckland, Auckland, New Zealand
| | - Srdjan Vlajkovic
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Kathryn Todd
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Faculty of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Peter S Freestone
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Carranza A, Howard LJ, Brown HE, Ametepe AS, Evans TA. Slit-independent guidance of longitudinal axons by Drosophila Robo3. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539901. [PMID: 37214810 PMCID: PMC10197545 DOI: 10.1101/2023.05.08.539901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Drosophila Robo3 is a member of the evolutionarily conserved Roundabout (Robo) receptor family and one of three Drosophila Robo paralogs. During embryonic ventral nerve cord development, Robo3 does not participate in canonical Slit-dependent midline repulsion, but instead regulates the formation of longitudinal axon pathways at specific positions along the medial-lateral axis. Longitudinal axon guidance by Robo3 is hypothesized to be Slit dependent, but this has not been directly tested. Here we create a series of Robo3 variants in which the N-terminal Ig1 domain is deleted or modified, in order to characterize the functional importance of Ig1 and Slit binding for Robo3's axon guidance activity. We show that Robo3 requires its Ig1 domain for interaction with Slit and for proper axonal localization in embryonic neurons, but deleting Ig1 from Robo3 only partially disrupts longitudinal pathway formation. Robo3 variants with modified Ig1 domains that cannot bind Slit retain proper localization and fully rescue longitudinal axon guidance. Our results indicate that Robo3 guides longitudinal axons independently of Slit, and that sequences both within and outside of Ig1 contribute to this Slit-independent activity.
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Affiliation(s)
- Abigail Carranza
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
- Current Address: Texas A&M University School of Medicine, Bryan, TX 77807
| | - LaFreda J. Howard
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
- Current Address: NAVA PBC, Washington, DC 20005
| | - Haley E. Brown
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
- Current Address: Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - Timothy A. Evans
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
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Abstract
The midbrain dopamine (mDA) system is composed of molecularly and functionally distinct neuron subtypes that mediate specific behaviours and are linked to various brain diseases. Considerable progress has been made in identifying mDA neuron subtypes, and recent work has begun to unveil how these neuronal subtypes develop and organize into functional brain structures. This progress is important for further understanding the disparate physiological functions of mDA neurons and their selective vulnerability in disease, and will ultimately accelerate therapy development. This Review discusses recent advances in our understanding of molecularly defined mDA neuron subtypes and their circuits, ranging from early developmental events, such as neuron migration and axon guidance, to their wiring and function, and future implications for therapeutic strategies.
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Freeman AK, Glendining KA, Jasoni CL. Developmental genes controlling neural circuit formation are expressed in the early postnatal hypothalamus and cellular lining of the third ventricle. J Neuroendocrinol 2021; 33:e13020. [PMID: 34423876 DOI: 10.1111/jne.13020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023]
Abstract
The arcuate nucleus of the hypothalamus is central in the regulation of body weight homeostasis through its ability to sense peripheral metabolic signals and relay them, through neural circuits, to other brain areas, ultimately affecting physiological and behavioural changes. The early postnatal development of these neural circuits is critical for normal body weight homeostasis, such that perturbations during this critical period can lead to obesity. The role for peripheral regulators of body weight homeostasis, including leptin, insulin and ghrelin, in this postnatal development is well described, yet some of the fundamental processes underpinning axonal and dendritic growth remain unclear. Here, we hypothesised that molecules known to regulate axonal and dendritic growth processes in other areas of the developing brain would be expressed in the postnatal arcuate nucleus and/or target nuclei where they would function to mediate the development of this circuitry. Using state-of-the-art RNAscope® technology, we have revealed the expression patterns of genes encoding Dcc/Netrin-1, Robo1/Slit1 and Fzd5/Wnt5a receptor/ligand pairs in the early postnatal mouse hypothalamus. We found that individual genes had unique expression patterns across developmental time in the arcuate nucleus, paraventricular nucleus of the hypothalamus, ventromedial nucleus of the hypothalamus, dorsomedial nucleus of the hypothalamus, median eminence and, somewhat unexpectedly, the third ventricle epithelium. These observations indicate a number of new molecular players in the development of neural circuits regulating body weight homeostasis, as well as novel molecular markers of tanycyte heterogeneity.
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Affiliation(s)
- Alice Katherine Freeman
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Kelly A Glendining
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Christine L Jasoni
- Centre for Neuroendocrinology, Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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6
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Soleilhavoup C, Travaglio M, Patrick K, Garção P, Boobalan E, Adolfs Y, Spriggs RV, Moles-Garcia E, Dhiraj D, Oosterveen T, Ferri SL, Abel T, Brodkin ES, Pasterkamp RJ, Brooks BP, Panman L. Nolz1 expression is required in dopaminergic axon guidance and striatal innervation. Nat Commun 2020; 11:3111. [PMID: 32561725 PMCID: PMC7305235 DOI: 10.1038/s41467-020-16947-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 05/29/2020] [Indexed: 11/24/2022] Open
Abstract
Midbrain dopaminergic (DA) axons make long longitudinal projections towards the striatum. Despite the importance of DA striatal innervation, processes involved in establishment of DA axonal connectivity remain largely unknown. Here we demonstrate a striatal-specific requirement of transcriptional regulator Nolz1 in establishing DA circuitry formation. DA projections are misguided and fail to innervate the striatum in both constitutive and striatal-specific Nolz1 mutant embryos. The lack of striatal Nolz1 expression results in nigral to pallidal lineage conversion of striatal projection neuron subtypes. This lineage switch alters the composition of secreted factors influencing DA axonal tract formation and renders the striatum non-permissive for dopaminergic and other forebrain tracts. Furthermore, transcriptomic analysis of wild-type and Nolz1−/− mutant striatal tissue led to the identification of several secreted factors that underlie the observed guidance defects and proteins that promote DA axonal outgrowth. Together, our data demonstrate the involvement of the striatum in orchestrating dopaminergic circuitry formation. The mechanisms regulating midbrain dopaminergic innervation during development are unclear. Here, the authors showed that Nolz1 is required for axonal guidance of dopaminergic neurons during embryonic development of the mouse brain.
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Affiliation(s)
- Clement Soleilhavoup
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Marco Travaglio
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Kieran Patrick
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Pedro Garção
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Elangovan Boobalan
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Youri Adolfs
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Ruth V Spriggs
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Emma Moles-Garcia
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Dalbir Dhiraj
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Tony Oosterveen
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Sarah L Ferri
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Ted Abel
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Edward S Brodkin
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104-3403, USA
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Brian P Brooks
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lia Panman
- MRC Toxicology Unit, University of Cambridge, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK.
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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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Solís-S JC, García-Solís P, Hernández-Chan NG, Zamorano-Martínez DA, Villagrán-Herrera ME, Hernández-Puga G, Vergara-Castañeda HA, Sánchez-Tusie AA, Varela-Echavarría A, Hernández-Montiel HL. Signals from the caudal diencephalon are required for the projection of the Interstitial Nuclei of Cajal. Int J Dev Neurosci 2018; 69:10-16. [PMID: 29908249 DOI: 10.1016/j.ijdevneu.2018.06.002] [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: 11/06/2017] [Revised: 06/07/2018] [Accepted: 06/07/2018] [Indexed: 10/14/2022] Open
Abstract
Axonal projection is controlled by discrete regions localized at the neuroepithelium, guiding the neurite growth during embryonic development. These regions exert their effect through the expression of a family of chemotropic molecules, which actively participate in the formation of neuronal connections of the central nervous system in vertebrates. Previous studies describe prosomere 1 (P1) as a possible organizer of axonal growth of the rostral rhombencephalon, contributing to the caudal projection of reticulospinal rhombencephalic neurons. This work studies the contribution of chemotropic signals from P1 or pretectal medial longitudinal fascicle (MLF) neurons upon the caudal projection of the interstitial nuclei of Cajal (INC). By using in ovo surgeries, retrograde axonal labeling, and immunohistochemical techniques, we were able to determine that the absence of P1 generates a failure in the INC caudal projection, while drastically diminishing the reticulospinal rhombencephalic neurons projections. The lack of INC projection significantly decreases the number of reticulospinal neurons projecting to the MLF. We found a 48.6% decrease in the projections to the MLF from the rostral and bulbar areas. Similarly, the observed decrease at prosomere 2 was 51.5%, with 61.8% and 32.4% for prosomeres 3 and 4, respectively; thus, constituting the most affected rostral regions. These results suggest the following possibilities: i, that the axons of the reticulospinal neurons employ the INC projection as a scaffold, fasciculating with this pioneer projection; and ii, that the P1 region, including pretectal MLF neurons, exerts a chemotropic effect upon the INC caudal projection. Nonetheless the identification of these chemotropic signals is still a pending task.
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Affiliation(s)
- Juan C Solís-S
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | - Pablo García-Solís
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | - Nancy G Hernández-Chan
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | | | | | - Gabriela Hernández-Puga
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | - Haydé A Vergara-Castañeda
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | - Ana A Sánchez-Tusie
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico
| | | | - Hebert L Hernández-Montiel
- Department of Biomedical Research, School of Medicine, Autonomous University of Queretaro, Qro., Mexico.
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9
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Vahedi-Hunter TA, Estep JA, Rosette KA, Rutlin ML, Wright KM, Riccomagno MM. Cas Adaptor Proteins Coordinate Sensory Axon Fasciculation. Sci Rep 2018; 8:5996. [PMID: 29662228 PMCID: PMC5902548 DOI: 10.1038/s41598-018-24261-x] [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: 07/31/2017] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
Development of complex neural circuits like the peripheral somatosensory system requires intricate mechanisms to ensure axons make proper connections. While much is known about ligand-receptor pairs required for dorsal root ganglion (DRG) axon guidance, very little is known about the cytoplasmic effectors that mediate cellular responses triggered by these guidance cues. Here we show that members of the Cas family of cytoplasmic signaling adaptors are highly phosphorylated in central projections of the DRG as they enter the spinal cord. Furthermore, we provide genetic evidence that Cas proteins regulate fasciculation of DRG sensory projections. These data establish an evolutionarily conserved requirement for Cas adaptor proteins during peripheral nervous system axon pathfinding. They also provide insight into the interplay between axonal fasciculation and adhesion to the substrate.
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Affiliation(s)
- Tyler A Vahedi-Hunter
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Jason A Estep
- Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Kylee A Rosette
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Michael L Rutlin
- Department of Biochemistry and Molecular Biophysics, Columbia College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Martin M Riccomagno
- Neuroscience Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA. .,Cell, Molecular and Developmental Biology Program, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA.
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10
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Kalaani J, Roche J, Hamade E, Badran B, Jaber M, Gaillard A, Prestoz L. Axon guidance molecule expression after cell therapy in a mouse model of Parkinson's disease. Restor Neurol Neurosci 2018; 34:877-895. [PMID: 27858721 DOI: 10.3233/rnn-150587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Cell therapy is a promising approach for Parkinson's disease (PD). Others and we have previously shown that transplantation of ventral mesencephalic fetal cells into substantia nigra (SN) in an animal model of PD enables anatomical and functional repair of the degenerated pathway. However, the molecular basis of this repair is still largely unknown. OBJECTIVE In this work, we studied the expression of several axon guidance molecules that may be implicated in the repair of the degenerated nigrostriatal pathway. METHODS The expression of axon guidance molecules was analyzed using qRT-PCR on five specific regions surrounding the nigrostriatal pathway (ventral mesencephalon (VM), thalamus (Thal), medial forebrain bundle (MFB), nucleus accumbens (NAcc) and caudate putamen (CPu)), one and seven days after lesion and transplantation. RESULTS We showed that mRNA expression of specific axon guidance molecules and their receptors is modified in structures surrounding the nigrostriatal pathway, suggesting their involvement in the axon guidance of grafted neurons. Moreover, we highlight a possible new role for semaphorin 7A in this repair. CONCLUSION Overall, our data provide a reliable basis to understand how axons of grafted neurons are able to navigate towards their targets and interact with the molecular environment in the adult brain. This should help to improve the efficiency of cell replacement approaches in PD.
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Affiliation(s)
- Joanna Kalaani
- Université de Poitiers, INSERM U-1084, Laboratoire de Neurosciences Expérimentales et Cliniques (LNEC), Poitiers, France
| | - Joëlle Roche
- Université de Poitiers, INSERM U-1084, Laboratoire de Neurosciences Expérimentales et Cliniques (LNEC), Poitiers, France
| | - Eva Hamade
- Doctoral School of Sciences and Technology (DSST-PRASE), Lebanese University, Hadath, Lebanon
| | - Bassam Badran
- Doctoral School of Sciences and Technology (DSST-PRASE), Lebanese University, Hadath, Lebanon
| | - Mohamed Jaber
- Université de Poitiers, INSERM U-1084, Laboratoire de Neurosciences Expérimentales et Cliniques (LNEC), Poitiers, France.,CHU de Poitiers, Poitiers, France
| | - Afsaneh Gaillard
- Université de Poitiers, INSERM U-1084, Laboratoire de Neurosciences Expérimentales et Cliniques (LNEC), Poitiers, France
| | - Laetitia Prestoz
- Université de Poitiers, INSERM U-1084, Laboratoire de Neurosciences Expérimentales et Cliniques (LNEC), Poitiers, France
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11
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Yuferov V, Zhang Y, Liang Y, Zhao C, Randesi M, Kreek MJ. Oxycodone Self-Administration Induces Alterations in Expression of Integrin, Semaphorin and Ephrin Genes in the Mouse Striatum. Front Psychiatry 2018; 9:257. [PMID: 29946272 PMCID: PMC6005861 DOI: 10.3389/fpsyt.2018.00257] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 05/24/2018] [Indexed: 11/28/2022] Open
Abstract
Oxycodone is one a commonly used medication for pain, and is also a widely abused prescription opioid, like other short-acting MOPr agonists. Neurochemical and structural adaptations in brain following chronic MOPr-agonist administration are thought to underlie pathogenesis and persistence of opiate addiction. Many axon guidance molecules, such as integrins, semaphorins, and ephrins may contribute to oxycodone-induced neuroadaptations through alterations in axon-target connections and synaptogenesis, that may be implicated in the behaviors associated with opiate addiction. However, little is known about this important area. The aim of this study is to investigate alterations in expression of selected integrin, semaphorin, ephrins, netrin, and slit genes in the nucleus accumbens (NAc) and caudate putamen (CPu) of mice following extended 14-day oxycodone self-administration (SA), using RNAseq. Methods: Total RNA from the NAc and CPu were isolated from adult male C57BL/6J mice within 1 h after the last session of oxycodone in a 14-day self-administration paradigm (4h/day, 0.25 mg/kg/infusion, FR1) or from yoked saline controls. Gene expressions were examined using RNA sequencing (RNA-Seq) technology. RNA-Seq libraries were prepared using Illumina's TruSeq® Stranded Total RNA LT kit. The reads were aligned to the mouse reference genome (version mm10) using STAR. DESeq2 was applied to the counts of protein coding genes to estimate the fold change between the treatment groups. False Discovery Rate (FDR) q < 0.1 were used to select genes that have a significant expression change. For selection of a subset of genes related to axon guidance pathway, REACTOME was used. Results: Among 38 known genes of the integrin, semaphorin, and ephrin gene families, RNA-seq data revealed up-regulation of six genes in the NAc: heterodimer receptor, integrins Itgal, Itgb2, and Itgam, and its ligand semaphorin Sema7a, two semaphorin receptors, plexins Plxnd1 and Plxdc1. There was down-regulation of eight genes in this region: two integrin genes Itga3 and Itgb8, semaphorins Sema3c, Sema4g, Sema6a, Sema6d, semaphorin receptor neuropilin Nrp2, and ephrin receptor Epha3. In the CPu, there were five differentially expressed axon guidance genes: up-regulation of three integrin genes, Itgal, Itgb2, Itga1, and down-regulation of Itga9 and ephrin Efna3 were thus observed. No significant alterations in expression of Netrin-1 or Slit were observed. Conclusion: We provide evidence for alterations in the expression of selective axon guidance genes in adult mouse brain following chronic self-administration of oxycodone. Further examination of oxycodone-induced changes in the expression of these specific axon guidance molecules and integrin genes in relation to behavior may provide new insights into development of addiction to oxycodone.
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Affiliation(s)
- Vadim Yuferov
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, United States
| | - Yong Zhang
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, United States
| | - Yupu Liang
- Research Bioinformatics, Clinical and Translational Science Award, The Rockefeller University, New York, NY, United States
| | - Connie Zhao
- Genomic Resource Center, The Rockefeller University, New York, NY, United States
| | - Matthew Randesi
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, United States
| | - Mary J Kreek
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, United States
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12
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Kim M, Bjorke B, Mastick GS. Motor neuron migration and positioning mechanisms: New roles for guidance cues. Semin Cell Dev Biol 2017; 85:78-83. [PMID: 29141180 DOI: 10.1016/j.semcdb.2017.11.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/10/2017] [Indexed: 11/24/2022]
Abstract
Motor neurons differentiate from progenitor cells and cluster as motor nuclei, settling next to the floor plate in the brain stem and spinal cord. Although precise positioning of motor neurons is critical for their functional input and output, the molecular mechanisms that guide motor neurons to their proper positions remain poorly understood. Here, we review recent evidence of motor neuron positioning mechanisms, highlighting situations in which motor neuron cell bodies can migrate, and experiments that show that their migration is regulated by axon guidance cues. The view that emerges is that motor neurons are actively trapped or restricted in static positions, as the cells balance a push in the dorsal direction by repulsive Slit/Robo cues and a pull in the ventral direction by attractive Netrin-1/DCC cues. These new functions of guidance cues are necessary fine-tuning to set up patterns of motor neurons at their proper positions in the neural tube during embryogenesis.
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Affiliation(s)
- Minkyung Kim
- Department of Biology, University of Nevada, Reno, NV 89557, USA.
| | - Brielle Bjorke
- Neuroscience Program, Carleton College, Northfield, MN 55057, USA
| | - Grant S Mastick
- Department of Biology, University of Nevada, Reno, NV 89557, USA
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13
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Brignani S, Pasterkamp RJ. Neuronal Subset-Specific Migration and Axonal Wiring Mechanisms in the Developing Midbrain Dopamine System. Front Neuroanat 2017; 11:55. [PMID: 28740464 PMCID: PMC5502286 DOI: 10.3389/fnana.2017.00055] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 06/20/2017] [Indexed: 01/01/2023] Open
Abstract
The midbrain dopamine (mDA) system is involved in the control of cognitive and motor behaviors, and is associated with several psychiatric and neurodegenerative diseases. mDA neurons receive diverse afferent inputs and establish efferent connections with many brain areas. Recent studies have unveiled a high level of molecular and cellular heterogeneity within the mDA system with specific subsets of mDA neurons displaying select molecular profiles and connectivity patterns. During mDA neuron development, molecular differences between mDA neuron subsets allow the establishment of subset-specific afferent and efferent connections and functional roles. In this review, we summarize and discuss recent work defining novel mDA neuron subsets based on specific molecular signatures. Then, molecular cues are highlighted that control mDA neuron migration during embryonic development and that facilitate the formation of selective patterns of efferent connections. The review focuses largely on studies that show differences in these mechanisms between different subsets of mDA neurons and for which in vivo data is available, and is concluded by a section that discusses open questions and provides directions for further research.
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Affiliation(s)
- Sara Brignani
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center UtrechtUtrecht, Netherlands
| | - R J Pasterkamp
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center UtrechtUtrecht, Netherlands
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14
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An oscillopathic approach to developmental dyslexia: From genes to speech processing. Behav Brain Res 2017; 329:84-95. [DOI: 10.1016/j.bbr.2017.03.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/14/2017] [Accepted: 03/18/2017] [Indexed: 12/27/2022]
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15
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Gore BB, Miller SM, Jo YS, Baird MA, Hoon M, Sanford CA, Hunker A, Lu W, Wong RO, Zweifel LS. Roundabout receptor 2 maintains inhibitory control of the adult midbrain. eLife 2017; 6. [PMID: 28394253 PMCID: PMC5419739 DOI: 10.7554/elife.23858] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 04/09/2017] [Indexed: 12/22/2022] Open
Abstract
The maintenance of excitatory and inhibitory balance in the brain is essential for its function. Here we find that the developmental axon guidance receptor Roundabout 2 (Robo2) is critical for the maintenance of inhibitory synapses in the adult ventral tegmental area (VTA), a brain region important for the production of the neurotransmitter dopamine. Following selective genetic inactivation of Robo2 in the adult VTA of mice, reduced inhibitory control results in altered neural activity patterns, enhanced phasic dopamine release, behavioral hyperactivity, associative learning deficits, and a paradoxical inversion of psychostimulant responses. These behavioral phenotypes could be phenocopied by selective inactivation of synaptic transmission from local GABAergic neurons of the VTA, demonstrating an important function for Robo2 in regulating the excitatory and inhibitory balance of the adult brain. DOI:http://dx.doi.org/10.7554/eLife.23858.001 Although no two people are alike, we all share the same basic brain structure. This similarity arises because the same developmental program takes place in every human embryo. Specific genes are activated in a designated sequence to generate the structure of a typical human brain. But what happens to these genes when development is complete – do they remain active in the adult brain? A gene known as Robo2 encodes a protein that helps neurons find their way through the developing brain. Many of these neurons will ultimately form part of the brain’s reward system. This is a network of brain regions that communicate with one another using a chemical called dopamine. The reward system contributes to motivation, learning and memory, and also underlies drug addiction. In certain mental illnesses such as Parkinson’s disease and schizophrenia, the dopamine-producing neurons in the reward system work incorrectly or die. To find out whether Robo2 is active in the mature nervous system, Gore et al. used genetic techniques to selectively remove the gene from the reward system of adult mice. Doing so reduced the ability of the dopamine neurons within the reward system to inhibit one another, which in turn increased their activity. This changed the behavior of the mice, making them hyperactive and less able to learn and remember. Cocaine makes normal mice more active; however, mice that lacked the Robo2 gene became less active when given cocaine. Overall, the work of Gore et al. suggests that developmental axon guidance genes remain important in the adult brain. Studying developmental genes such as Robo2 may therefore open up new treatment possibilities for a number of mental illnesses and brain disorders. DOI:http://dx.doi.org/10.7554/eLife.23858.002
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Affiliation(s)
- Bryan B Gore
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, United States.,Department of Pharmacology, University of Washington, Seattle, United States
| | - Samara M Miller
- Department of Pharmacology, University of Washington, Seattle, United States
| | - Yong Sang Jo
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, United States.,Department of Pharmacology, University of Washington, Seattle, United States
| | - Madison A Baird
- Department of Pharmacology, University of Washington, Seattle, United States
| | - Mrinalini Hoon
- Department of Biological Structure, University of Washington, Seattle, United States
| | - Christina A Sanford
- Department of Pharmacology, University of Washington, Seattle, United States
| | - Avery Hunker
- Department of Pharmacology, University of Washington, Seattle, United States
| | - Weining Lu
- Department of Medicine, Renal Section, Boston University Medical Center, Boston, United States
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, United States
| | - Larry S Zweifel
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, United States.,Department of Pharmacology, University of Washington, Seattle, United States
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16
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Bjorke B, Shoja-Taheri F, Kim M, Robinson GE, Fontelonga T, Kim KT, Song MR, Mastick GS. Contralateral migration of oculomotor neurons is regulated by Slit/Robo signaling. Neural Dev 2016; 11:18. [PMID: 27770832 PMCID: PMC5075191 DOI: 10.1186/s13064-016-0073-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 10/11/2016] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Oculomotor neurons develop initially like typical motor neurons, projecting axons out of the ventral midbrain to their ipsilateral targets, the extraocular muscles. However, in all vertebrates, after the oculomotor nerve (nIII) has reached the extraocular muscle primordia, the cell bodies that innervate the superior rectus migrate to join the contralateral nucleus. This motor neuron migration represents a unique strategy to form a contralateral motor projection. Whether migration is guided by diffusible cues remains unknown. METHODS We examined the role of Slit chemorepellent signals in contralateral oculomotor migration by analyzing mutant mouse embryos. RESULTS We found that the ventral midbrain expresses high levels of both Slit1 and 2, and that oculomotor neurons express the repellent Slit receptors Robo1 and Robo2. Therefore, Slit signals are in a position to influence the migration of oculomotor neurons. In Slit 1/2 or Robo1/2 double mutant embryos, motor neuron cell bodies migrated into the ventral midbrain on E10.5, three days prior to normal migration. These early migrating neurons had leading projections into and across the floor plate. In contrast to the double mutants, embryos which were mutant for single Slit or Robo genes did not have premature migration or outgrowth on E10.5, demonstrating a cooperative requirement of Slit1 and 2, as well as Robo1 and 2. To test how Slit/Robo midline repulsion is modulated, we found that the normal migration did not require the receptors Robo3 and CXCR4, or the chemoattractant, Netrin 1. The signal to initiate contralateral migration is likely autonomous to the midbrain because oculomotor neurons migrate in embryos that lack either nerve outgrowth or extraocular muscles, or in cultured midbrains that lacked peripheral tissue. CONCLUSION Overall, our results demonstrate that a migratory subset of motor neurons respond to floor plate-derived Slit repulsion to properly control the timing of contralateral migration.
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Affiliation(s)
- Brielle Bjorke
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | | | - Minkyung Kim
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | - G Eric Robinson
- Department of Biology, University of Nevada, Reno, NV, 89557, USA
| | | | - Kyung-Tai Kim
- School of Life Sciences, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, 500-712, Republic of Korea
| | - Mi-Ryoung Song
- School of Life Sciences, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, 500-712, Republic of Korea
| | - Grant S Mastick
- Department of Biology, University of Nevada, Reno, NV, 89557, USA.
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17
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Alavi M, Song M, King GLA, Gillis T, Propst R, Lamanuzzi M, Bousum A, Miller A, Allen R, Kidd T. Dscam1 Forms a Complex with Robo1 and the N-Terminal Fragment of Slit to Promote the Growth of Longitudinal Axons. PLoS Biol 2016; 14:e1002560. [PMID: 27654876 PMCID: PMC5031454 DOI: 10.1371/journal.pbio.1002560] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 08/23/2016] [Indexed: 11/19/2022] Open
Abstract
The Slit protein is a major midline repellent for central nervous system (CNS) axons. In vivo, Slit is proteolytically cleaved into N- and C-terminal fragments, but the biological significance of this is unknown. Analysis in the Drosophila ventral nerve cord of a slit allele (slit-UC) that cannot be cleaved revealed that midline repulsion is still present but longitudinal axon guidance is disrupted, particularly across segment boundaries. Double mutants for the Slit receptors Dscam1 and robo1 strongly resemble the slit-UC phenotype, suggesting they cooperate in longitudinal axon guidance, and through biochemical approaches, we found that Dscam1 and Robo1 form a complex dependent on Slit-N. In contrast, Robo1 binding alone shows a preference for full-length Slit, whereas Dscam1 only binds Slit-N. Using a variety of transgenes, we demonstrated that Dscam1 appears to modify the output of Robo/Slit complexes so that signaling is no longer repulsive. Our data suggest that the complex is promoting longitudinal axon growth across the segment boundary. The ability of Dscam1 to modify the output of other receptors in a ligand-dependent fashion may be a general principle for Dscam proteins.
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Affiliation(s)
- Maryam Alavi
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Minmin Song
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | | | - Taylor Gillis
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Robert Propst
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Matthew Lamanuzzi
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Adam Bousum
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Amanda Miller
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Ryan Allen
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Thomas Kidd
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
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18
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Carballo-Molina OA, Sánchez-Navarro A, López-Ornelas A, Lara-Rodarte R, Salazar P, Campos-Romo A, Ramos-Mejía V, Velasco I. Semaphorin 3C Released from a Biocompatible Hydrogel Guides and Promotes Axonal Growth of Rodent and Human Dopaminergic Neurons. Tissue Eng Part A 2016; 22:850-61. [PMID: 27174503 PMCID: PMC4913502 DOI: 10.1089/ten.tea.2016.0008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 05/12/2016] [Indexed: 12/21/2022] Open
Abstract
Cell therapy in experimental models of Parkinson's disease replaces the lost dopamine neurons (DAN), but we still need improved methods to guide dopaminergic axons (DAx) of grafted neurons to make proper connections. The protein Semaphorin 3C (Sema3C) attracts DAN axons and enhances their growth. In this work, we show that the hydrogel PuraMatrix, a self-assembling peptide-based matrix, incorporates Sema3C and releases it steadily during 4 weeks. We also tested if hydrogel-delivered Sema3C attracts DAx using a system of rat midbrain explants embedded in collagen gels. We show that Sema3C released by this hydrogel attracts DAx, in a similar way to pretectum, which is known to attract growing DAN axons. We assessed the effect of Sema3C on the growth of DAx using microfluidic devices. DAN from rat midbrain or those differentiated from human embryonic stem cells showed enhanced axonal extension when exposed to hydrogel-released Sema3C, similar to soluble Sema3C. Notably, DAN of human origin express the cognate Sema3C receptors, Neuropilin1 and Neuropilin2. These results show that PuraMatrix is able to incorporate and release Sema3C, and such delivery guides and promotes the axonal growth of DAN. This biocompatible hydrogel might be useful as a Sema3C carrier for in vivo studies in parkinsonian animal models.
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Affiliation(s)
- Oscar A. Carballo-Molina
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de México, México, D.F., México
- Laboratorio de Reprogramación Celular IFC/UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
| | - Andrea Sánchez-Navarro
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de México, México, D.F., México
- Laboratorio de Reprogramación Celular IFC/UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
| | - Adolfo López-Ornelas
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de México, México, D.F., México
- Laboratorio de Reprogramación Celular IFC/UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
| | - Rolando Lara-Rodarte
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de México, México, D.F., México
- Laboratorio de Reprogramación Celular IFC/UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
| | - Patricia Salazar
- GENYO: Centre for Genomics and Oncological Research Pfizer-University of Granada-Junta de Andalucía, PTS Granada, Spain
| | - Aurelio Campos-Romo
- Unidad Periférica de Neurociencias Facultad de Medicina-UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
| | - Verónica Ramos-Mejía
- GENYO: Centre for Genomics and Oncological Research Pfizer-University of Granada-Junta de Andalucía, PTS Granada, Spain
| | - Iván Velasco
- Instituto de Fisiología Celular—Neurociencias, Universidad Nacional Autónoma de México, México, D.F., México
- Laboratorio de Reprogramación Celular IFC/UNAM en el Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez,” México, D.F., México
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19
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Tamariz E, Varela-Echavarría A. The discovery of the growth cone and its influence on the study of axon guidance. Front Neuroanat 2015; 9:51. [PMID: 26029056 PMCID: PMC4432662 DOI: 10.3389/fnana.2015.00051] [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: 12/23/2014] [Accepted: 04/13/2015] [Indexed: 11/25/2022] Open
Abstract
For over a century, there has been a great deal of interest in understanding how neural connectivity is established during development and regeneration. Interest in the latter arises from the possibility that knowledge of this process can be used to re-establish lost connections after lesion or neurodegeneration. At the end of the XIX century, Santiago Ramón y Cajal discovered that the distal tip of growing axons contained a structure that he called the growth cone. He proposed that this structure enabled the axon's oriented growth in response to attractants, now known as chemotropic molecules. He further proposed that the physical properties of the surrounding tissues could influence the growth cone and the direction of growth. This seminal discovery afforded a plausible explanation for directed axonal growth and has led to the discovery of axon guidance mechanisms that include diffusible attractants and repellants and guidance cues anchored to cell membranes or extracellular matrix. In this review the major events in the development of this field are discussed.
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Affiliation(s)
- Elisa Tamariz
- Instituto de Ciencias de la Salud, Universidad VeracruzanaXalapa, Mexico
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20
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Boeckx C, Benítez-Burraco A. Globularity and language-readiness: generating new predictions by expanding the set of genes of interest. Front Psychol 2014; 5:1324. [PMID: 25505436 PMCID: PMC4243498 DOI: 10.3389/fpsyg.2014.01324] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 10/31/2014] [Indexed: 12/30/2022] Open
Abstract
This study builds on the hypothesis put forth in Boeckx and Benítez-Burraco (2014), according to which the developmental changes expressed at the levels of brain morphology and neural connectivity that resulted in a more globular braincase in our species were crucial to understand the origins of our language-ready brain. Specifically, this paper explores the links between two well-known 'language-related' genes like FOXP2 and ROBO1 implicated in vocal learning and the initial set of genes of interest put forth in Boeckx and Benítez-Burraco (2014), with RUNX2 as focal point. Relying on the existing literature, we uncover potential molecular links that could be of interest to future experimental inquiries into the biological foundations of language and the testing of our initial hypothesis. Our discussion could also be relevant for clinical linguistics and for the interpretation of results from paleogenomics.
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Affiliation(s)
- Cedric Boeckx
- Catalan Institute for Advanced Studies and Research (ICREA)Barcelona, Spain
- Department of Linguistics, Universitat de BarcelonaBarcelona, Spain
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21
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Brown JA, Sherrod SD, Goodwin CR, Brewer B, Yang L, Garbett KA, Li D, McLean JA, Wikswo JP, Mirnics K. Metabolic consequences of interleukin-6 challenge in developing neurons and astroglia. J Neuroinflammation 2014; 11:183. [PMID: 25374324 PMCID: PMC4233071 DOI: 10.1186/s12974-014-0183-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 10/11/2014] [Indexed: 02/02/2023] Open
Abstract
Background Maternal immune activation and subsequent interleukin-6 (IL-6) induction disrupt normal brain development and predispose the offspring to developing autism and schizophrenia. While several proteins have been identified as having some link to these developmental disorders, their prevalence is still small and their causative role, if any, is not well understood. However, understanding the metabolic consequences of environmental predisposing factors could shed light on disorders such as autism and schizophrenia. Methods To gain a better understanding of the metabolic consequences of IL-6 exposure on developing central nervous system (CNS) cells, we separately exposed developing neuron and astroglia cultures to IL-6 for 2 hours while collecting effluent from our gravity-fed microfluidic chambers. By coupling microfluidic technologies to ultra-performance liquid chromatography-ion mobility-mass spectrometry (UPLC-IM-MS), we were able to characterize the metabolic response of these CNS cells to a narrow window of IL-6 exposure. Results Our results revealed that 1) the use of this technology, due to its superb media volume:cell volume ratio, is ideally suited for analysis of cell-type-specific exometabolome signatures; 2) developing neurons have low secretory activity at baseline, while astroglia show strong metabolic activity; 3) both neurons and astroglia respond to IL-6 exposure in a cell type-specific fashion; 4) the astroglial response to IL-6 stimulation is predominantly characterized by increased levels of metabolites, while neurons mostly depress their metabolic activity; and 5) disturbances in glycerophospholipid metabolism and tryptophan/kynurenine metabolite secretion are two putative mechanisms by which IL-6 affects the developing nervous system. Conclusions Our findings are potentially critical for understanding the mechanism by which IL-6 disrupts brain function, and they provide information about the molecular cascade that links maternal immune activation to developmental brain disorders. Electronic supplementary material The online version of this article (doi:10.1186/s12974-014-0183-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jacquelyn A Brown
- Department of Psychiatry, 465 21st Avenue South, Vanderbilt University, Nashville, TN, 37232, USA. .,Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA.
| | - Stacy D Sherrod
- Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Physics and Astronomy, 6301 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA.
| | - Cody R Goodwin
- Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Chemistry, 5421 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA.
| | - Bryson Brewer
- Department of Mechanical Engineering, 333 Olin Hall, Vanderbilt University, Nashville, TN, 37235, USA.
| | - Lijie Yang
- Department of Mechanical Engineering, 333 Olin Hall, Vanderbilt University, Nashville, TN, 37235, USA.
| | - Krassimira A Garbett
- Department of Psychiatry, 465 21st Avenue South, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Deyu Li
- Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Mechanical Engineering, 333 Olin Hall, Vanderbilt University, Nashville, TN, 37235, USA.
| | - John A McLean
- Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Chemistry, 5421 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA.
| | - John P Wikswo
- Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Physics and Astronomy, 6301 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Department of Biomedical Engineering, 5824 Stevenson Center, Vanderbilt University, Nashville, 37235, TN, USA. .,Department of Molecular Physiology and Biophysics, 702 Light Hall, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Károly Mirnics
- Department of Psychiatry, 465 21st Avenue South, Vanderbilt University, Nashville, TN, 37232, USA. .,Vanderbilt Institute for Integrative Biosystems Research and Education, 6809 Stevenson Center, Vanderbilt University, Nashville, TN, 37235, USA. .,Vanderbilt Kennedy Center for Research on Human Development, 110 Magnolia Circle, Vanderbilt University, Nashville, TN, 37203, USA. .,Department of Psychiatry, University of Szeged, 6725, Szeged, Hungary.
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Two miRNA clusters, miR-34b/c and miR-449, are essential for normal brain development, motile ciliogenesis, and spermatogenesis. Proc Natl Acad Sci U S A 2014; 111:E2851-7. [PMID: 24982181 DOI: 10.1073/pnas.1407777111] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ablation of a single miRNA gene rarely leads to a discernable developmental phenotype in mice, in some cases because of compensatory effects by other functionally related miRNAs. Here, we report that simultaneous inactivation of two functionally related miRNA clusters (miR-34b/c and miR-449) encoding five miRNAs (miR-34b, miR-34c, miR-449a, miR-449b, and miR-449c) led to sexually dimorphic, partial perinatal lethality, growth retardation, and infertility. These developmental defects correlated with the dysregulation of ∼ 240 target genes, which are mainly involved in three major cellular functions, including cell-fate control, brain development and microtubule dynamics. Our data demonstrate an essential role of a miRNA family in brain development, motile ciliogenesis, and spermatogenesis.
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García-Peña CM, Kim M, Frade-Pérez D, Avila-González D, Téllez E, Mastick GS, Tamariz E, Varela-Echavarría A. Ascending midbrain dopaminergic axons require descending GAD65 axon fascicles for normal pathfinding. Front Neuroanat 2014; 8:43. [PMID: 24926237 PMCID: PMC4046268 DOI: 10.3389/fnana.2014.00043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/19/2014] [Indexed: 12/22/2022] Open
Abstract
The Nigrostriatal pathway (NSP) is formed by dopaminergic axons that project from the ventral midbrain to the dorsolateral striatum as part of the medial forebrain bundle. Previous studies have implicated chemotropic proteins in the formation of the NSP during development but little is known of the role of substrate-anchored signals in this process. We observed in mouse and rat embryos that midbrain dopaminergic axons ascend in close apposition to descending GAD65-positive axon bundles throughout their trajectory to the striatum. To test whether such interaction is important for dopaminergic axon pathfinding, we analyzed transgenic mouse embryos in which the GAD65 axon bundle was reduced by the conditional expression of the diphtheria toxin. In these embryos we observed dopaminergic misprojection into the hypothalamic region and abnormal projection in the striatum. In addition, analysis of Robo1/2 and Slit1/2 knockout embryos revealed that the previously described dopaminergic misprojection in these embryos is accompanied by severe alterations in the GAD65 axon scaffold. Additional studies with cultured dopaminergic neurons and whole embryos suggest that NCAM and Robo proteins are involved in the interaction of GAD65 and dopaminergic axons. These results indicate that the fasciculation between descending GAD65 axon bundles and ascending dopaminergic axons is required for the stereotypical NSP formation during brain development and that known guidance cues may determine this projection indirectly by instructing the pathfinding of the axons that are part of the GAD65 axon scaffold.
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Affiliation(s)
- Claudia M García-Peña
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
| | - Minkyung Kim
- Department of Biology, University of Nevada Reno, NV, USA
| | - Daniela Frade-Pérez
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
| | - Daniela Avila-González
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
| | - Elisa Téllez
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
| | | | - Elisa Tamariz
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
| | - Alfredo Varela-Echavarría
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México Querétaro, México
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Hegarty SV, Collins LM, Gavin AM, Roche SL, Wyatt SL, Sullivan AM, O'Keeffe GW. Canonical BMP-Smad signalling promotes neurite growth in rat midbrain dopaminergic neurons. Neuromolecular Med 2014; 16:473-89. [PMID: 24682653 DOI: 10.1007/s12017-014-8299-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 03/07/2014] [Indexed: 01/01/2023]
Abstract
Ventral midbrain (VM) dopaminergic (DA) neurons project to the dorsal striatum via the nigrostriatal pathway to regulate voluntary movements, and their loss leads to the motor dysfunction seen in Parkinson's disease (PD). Despite recent progress in the understanding of VM DA neurogenesis, the factors regulating nigrostriatal pathway development remain largely unknown. The bone morphogenetic protein (BMP) family regulates neurite growth in the developing nervous system and may contribute to nigrostriatal pathway development. Two related members of this family, BMP2 and growth differentiation factor (GDF)5, have neurotrophic effects, including promotion of neurite growth, on cultured VM DA neurons. However, the molecular mechanisms regulating their effects on DA neurons are unknown. By characterising the temporal expression profiles of endogenous BMP receptors (BMPRs) in the developing and adult rat VM and striatum, this study identified BMP2 and GDF5 as potential regulators of nigrostriatal pathway development. Furthermore, through the use of noggin, dorsomorphin and BMPR/Smad plasmids, this study demonstrated that GDF5- and BMP2-induced neurite outgrowth from cultured VM DA neurons is dependent on BMP type I receptor activation of the Smad 1/5/8 signalling pathway.
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Affiliation(s)
- Shane V Hegarty
- Department of Anatomy and Neuroscience, Biosciences Institute, University College Cork, Cork, Ireland
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25
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Mohr R, Neckel P, Zhang Y, Stachon S, Nothelfer K, Schaeferhoff K, Obermayr F, Bonin M, Just L. Molecular and cell biological effects of 3,5,3′-triiodothyronine on progenitor cells of the enteric nervous system in vitro. Stem Cell Res 2013; 11:1191-205. [DOI: 10.1016/j.scr.2013.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 07/15/2013] [Accepted: 08/01/2013] [Indexed: 01/18/2023] Open
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26
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Cornide-Petronio ME, Barreiro-Iglesias A. Role of Slit and Robo proteins in the development of dopaminergic neurons. Dev Neurosci 2013; 35:285-92. [PMID: 23796505 DOI: 10.1159/000351023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/28/2013] [Indexed: 11/19/2022] Open
Abstract
Dopamine plays a number of important roles in the nervous system and the dopaminergic system is affected in several brain disorders. It is therefore of great interest to study the axonal guidance systems that specifically participate in the correct establishment of dopaminergic projections during development and possibly during regenerative processes. In recent years, several reports have shown that Slits and their Robo receptors control the growth of longitudinal (both ascending and descending) mesodiencephalic dopaminergic axons to their appropriate target areas. In vitro studies have shown that Slit1, 2 and 3 are potent repellents of dopamine neurite extension. In vivo studies using both mice and zebrafish mutants for Slits and Robos have shown that Slits and Robos control the lateral and dorsoventral positioning of dopaminergic longitudinal projections during early development. In the present review, we aimed to compile the existing knowledge from both in vitro and in vivo studies on the role of Slit and Robo proteins in the development of dopaminergic neurons as a basis for future studies.
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Affiliation(s)
- María Eugenia Cornide-Petronio
- Department of Cell Biology and Ecology, CIBUS, Faculty of Biology, University of Santiago de Compostela, Santiago de Compostela, Spain
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27
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Luo C, Qu H, Ma J, Wang J, Li C, Yang C, Hu X, Li N, Shu D. Genome-wide association study of antibody response to Newcastle disease virus in chicken. BMC Genet 2013; 14:42. [PMID: 23663563 PMCID: PMC3654938 DOI: 10.1186/1471-2156-14-42] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 05/06/2013] [Indexed: 11/21/2022] Open
Abstract
Background Since the first outbreak in Indonesia in 1926, Newcastle disease has become one of the most common and contagious bird diseases throughout the world. To date, enhancing host antibody response by vaccination remains the most efficient strategy to control outbreaks of Newcastle disease. Antibody response plays an important role in host resistance to Newcastle disease, and selection for antibody response can effectively improve disease resistance in chickens. However, the molecular basis of the variation in antibody response to Newcastle disease virus (NDV) is not clear. The aim of this study was to detect genes modulating antibody response to NDV by a genome-wide association study (GWAS) in chickens. Results To identify genes or chromosomal regions associated with antibody response to NDV after immunization, a GWAS was performed using 39,833 SNP markers in a chicken F2 resource population derived from a cross between two broiler lines that differed in their resistance. Two SNP effects reached 5% Bonferroni genome-wide significance (P<1.26×10-6). These two SNPs, rs15354805 and rs15355555, were both on chicken (Gallus gallus) chromosome 1 and spanned approximately 600 Kb, from 100.4 Mb to 101.0 Mb. Rs15354805 is in intron 7 of the chicken Roundabout, axon guidance receptor, homolog 2 (ROBO2) gene, and rs15355555 is located about 243 Kb upstream of ROBO2. Rs15354805 explained 5% of the phenotypic variation in antibody response to NDV, post immunization, in chickens. Rs15355555 had a similar effect as rs15354805 because of its linkage disequilibrium with rs15354805 (r2=0.98). Conclusion The region at about 100 Mb from the proximal end of chicken chromosome 1, including the ROBO1 and ROBO2 genes, has a strong effect on the antibody response to the NDV in chickens. This study paves the way for further research on the host immune response to NDV.
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Affiliation(s)
- Chenglong Luo
- Institute of Animal Science, Guangdong Academy of Agricultural Sciences, 1 Dafeng 1st Street, Wushan, Tianhe District, Guangzhou 510640, Guangdong, China
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Midbrain dopaminergic neurons: a review of the molecular circuitry that regulates their development. Dev Biol 2013; 379:123-38. [PMID: 23603197 DOI: 10.1016/j.ydbio.2013.04.014] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/27/2013] [Accepted: 04/12/2013] [Indexed: 12/21/2022]
Abstract
Dopaminergic (DA) neurons of the ventral midbrain (VM) play vital roles in the regulation of voluntary movement, emotion and reward. They are divided into the A8, A9 and A10 subgroups. The development of the A9 group of DA neurons is an area of intense investigation to aid the generation of these neurons from stem cell sources for cell transplantation approaches to Parkinson's disease (PD). This review discusses the molecular processes that are involved in the identity, specification, maturation, target innervation and survival of VM DA neurons during development. The complex molecular interactions of a number of genetic pathways are outlined, as well as recent advances in the mechanisms that regulate subset identity within the VM DA neuronal pool. A thorough understanding of the cellular and molecular mechanisms involved in the development of VM DA neurons will greatly facilitate the use of cell replacement therapy for the treatment of PD.
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Torigoe M, Yamauchi K, Tamada A, Matsuda I, Aiba A, Castellani V, Murakami F. Role of neuropilin-2 in the ipsilateral growth of midbrain dopaminergic axons. Eur J Neurosci 2013; 37:1573-83. [PMID: 23534961 DOI: 10.1111/ejn.12190] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 01/01/2023]
Abstract
Axonal projections in the CNS can be categorized as either crossed or uncrossed. Crossing and uncrossing of axons has been explained by attractive and repulsive molecules like Netrin-1 and Slits, which are secreted by midline structures. However, uncrossed projections can be established even in double knockout mice of slit1 and slit2 or of roundabout1 (robo1) and robo2, two receptors for Slits. Here, we found that a novel mechanism mediated by Neuropilin-2 (Nrp2) contributes to the formation of uncrossed projections of midbrain dopaminergic neurons (mDANs). Nrp2 transcriptional activities were detected in a subset of mDANs, and its protein was expressed in mDAN axons growing through the ipsilateral diencephalon. In nrp2(lac) (Z) (/lac) (Z) mice, mDAN axons aberrantly grew toward the ventral midline and even crossed it, suggesting that Nrp2 is necessary for the development of mDAN ipsilateral projections. We investigated the involvement of Semaphorin 3B (Sema3B) and Sema3F, two ligands of Nrp2, by analysing mDAN axon trajectories in single or double knockout mice. In both cases, mDAN axons still projected ipsilaterally, suggesting the involvement mechanisms independent of these Sema3s. Nrp2-deficient mDAN axons retained their responsiveness to Slit2, demonstrating that aberrant mDAN axons in nrp2(lac) (Z) (/lac) (Z) mice were not indirectly mediated by alterations in Slit/Robo signaling. Taken together, our results indicate that a novel mechanism mediated by Nrp2 contributes to the establishment of uncrossed projections by mDAN axons.
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Affiliation(s)
- Makio Torigoe
- Laboratory of Neuroscience, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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Schweitzer J, Löhr H, Bonkowsky JL, Hübscher K, Driever W. Sim1a and Arnt2 contribute to hypothalamo-spinal axon guidance by regulating Robo2 activity via a Robo3-dependent mechanism. Development 2013; 140:93-106. [PMID: 23222439 DOI: 10.1242/dev.087825] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Precise spatiotemporal control of axon guidance factor expression is a prerequisite for formation of functional neuronal connections. Although Netrin/Dcc- and Robo/Slit-mediated attractive and repulsive guidance of commissural axons have been extensively studied, little is known about mechanisms controlling mediolateral positioning of longitudinal axons in vertebrates. Here, we use a genetic approach in zebrafish embryos to study pathfinding mechanisms of dopaminergic and neuroendocrine longitudinal axons projecting from the hypothalamus into hindbrain and spinal cord. The transcription factors Sim1a and Arnt2 contribute to differentiation of a defined population of dopaminergic and neuroendocrine neurons. We show that both factors also control aspects of axon guidance: Sim1a or Arnt2 depletion results in displacement of hypothalamo-spinal longitudinal axons towards the midline. This phenotype is suppressed in robo3 guidance receptor mutant embryos. In the absence of Sim1a and Arnt2, expression of the robo3 splice isoform robo3a.1 is increased in the hypothalamus, indicating negative control of robo3a.1 transcription by these factors. We further provide evidence that increased Robo3a.1 levels interfere with Robo2-mediated repulsive axon guidance. Finally, we show that the N-terminal domain unique to Robo3a.1 mediates the block of Robo2 repulsive activity. Therefore, Sim1a and Arnt2 contribute to control of lateral positioning of longitudinal hypothalamic-spinal axons by negative regulation of robo3a.1 expression, which in turn attenuates the repulsive activity of Robo2.
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Affiliation(s)
- Jörn Schweitzer
- Developmental Biology, Institute Biology 1, Faculty of Biology, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany.
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31
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Prestoz L, Jaber M, Gaillard A. Dopaminergic axon guidance: which makes what? Front Cell Neurosci 2012; 6:32. [PMID: 22866028 PMCID: PMC3408579 DOI: 10.3389/fncel.2012.00032] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 07/15/2012] [Indexed: 01/30/2023] Open
Abstract
Mesotelencephalic pathways in the adult central nervous system have been studied in great detail because of their implication in major physiological functions as well as in psychiatric, neurological, and neurodegenerative diseases. However, the ontogeny of these pathways and the molecular mechanisms that guide dopaminergic axons during embryogenesis have been only recently studied. This line of research is of crucial interest for the repair of lesioned circuits in adulthood following neurodegenerative diseases or common traumatic injuries. For instance, in the adult, the anatomic and functional repair of the nigrostriatal pathway following dopaminergic embryonic neuron transplantation suggests that specific guidance cues exist which govern embryonic fibers outgrowth, and suggests that axons from transplanted embryonic cells are able to respond to theses cues, which then guide them to their final targets. In this review, we first synthesize the work that has been performed in the last few years on developing mesotelencephalic pathways, and summarize the current knowledge on the identity of cellular and molecular signals thought to be involved in establishing mesotelencephalic dopaminergic neuronal connectivity during embryogenesis in the central nervous system of rodents. Then, we review the modulation of expression of these molecular signals in the lesioned adult brain and discuss their potential role in remodeling the mesotelencephalic dopaminergic circuitry, with a particular focus on Parkinson's disease (PD). Identifying guidance molecules involved in the connection of grafted cells may be useful for cellular therapy in Parkinsonian patients, as these molecules may help direct axons from grafted cells along the long distance they have to travel from the substantia nigra to the striatum.
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Affiliation(s)
- Laetitia Prestoz
- Experimental and Clinical Neurosciences Laboratory, Research Group on Cellular Therapies in Brain Diseases, INSERM U1084, University of PoitiersPoitiers, France.
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Sgadò P, Ferretti E, Grbec D, Bozzi Y, Simon HH. The atypical homeoprotein Pbx1a participates in the axonal pathfinding of mesencephalic dopaminergic neurons. Neural Dev 2012; 7:24. [PMID: 22748019 PMCID: PMC3407702 DOI: 10.1186/1749-8104-7-24] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Accepted: 07/02/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The pre B-cell leukemia transcription factor 1 (Pbx1) genes belong to the three amino acid loop extension family of homeodomain proteins that form hetero-oligomeric complexes with other homeodomain transcription factors, thereby modulating target specificity, DNA binding affinity and transcriptional activity of their molecular associates. RESULTS Here, we provide evidence that Pbx1 is expressed in mesencephalic dopaminergic neurons from embryonic day 11 into adulthood and determines some of the cellular properties of this neuronal population. In Pbx1-deficient mice, the mesencephalic dopaminergic axons stall during mid-gestation at the border between di- and telencephalon before entering the ganglionic eminence, leading to a loose organization of the axonal bundle and partial misrouting. In Pbx1-deficient dopaminergic neurons, the high affinity netrin-1 receptor, deleted in colon cancer (DCC), is down-regulated. Interestingly, we found several conserved Pbx1 binding sites in the first intron of DCC, suggesting a direct regulation of DCC transcription by Pbx1. CONCLUSIONS The expression of Pbx1 in dopaminergic neurons and its regulation of DCC expression make it an important player in defining the axonal guidance of the midbrain dopaminergic neurons, with possible implications for the normal physiology of the nigro-striatal system as well as processes related to the degeneration of neurons during the course of Parkinson's disease.
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Affiliation(s)
- Paola Sgadò
- Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento, Trento, Italy.
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33
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Sakai N, Kaprielian Z. Guidance of longitudinally projecting axons in the developing central nervous system. Front Mol Neurosci 2012; 5:59. [PMID: 22586366 PMCID: PMC3343325 DOI: 10.3389/fnmol.2012.00059] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/14/2012] [Indexed: 12/26/2022] Open
Abstract
The directed and stereotypical growth of axons to their synaptic targets is a crucial phase of neural circuit formation. Many axons in the developing vertebrate and invertebrate central nervous systems (CNSs), including those that remain on their own (ipsilateral), and those that cross over to the opposite (commissural), side of the midline project over long distances along the anterior-posterior (A-P) body axis within precisely positioned longitudinally oriented tracts to facilitate the transmission of information between CNS regions. Despite the widespread distribution and functional importance of these longitudinal tracts, the mechanisms that regulate their formation and projection to poorly characterized synaptic targets remain largely unknown. Nevertheless, recent studies carried out in a variety of invertebrate and vertebrate model systems have begun to elucidate the molecular logic that controls longitudinal axon guidance.
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Affiliation(s)
- Nozomi Sakai
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx NY, USA
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Bravo-Ambrosio A, Mastick G, Kaprielian Z. Motor axon exit from the mammalian spinal cord is controlled by the homeodomain protein Nkx2.9 via Robo-Slit signaling. Development 2012; 139:1435-46. [PMID: 22399681 PMCID: PMC3308178 DOI: 10.1242/dev.072256] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2012] [Indexed: 01/11/2023]
Abstract
Mammalian motor circuits control voluntary movements by transmitting signals from the central nervous system (CNS) to muscle targets. To form these circuits, motor neurons (MNs) must extend their axons out of the CNS. Although exit from the CNS is an indispensable phase of motor axon pathfinding, the underlying molecular mechanisms remain obscure. Here, we present the first identification of a genetic pathway that regulates motor axon exit from the vertebrate spinal cord, utilizing spinal accessory motor neurons (SACMNs) as a model system. SACMNs are a homogeneous population of spinal MNs with axons that leave the CNS through a discrete lateral exit point (LEP) and can be visualized by the expression of the cell surface protein BEN. We show that the homeodomain transcription factor Nkx2.9 is selectively required for SACMN axon exit and identify the Robo2 guidance receptor as a likely downstream effector of Nkx2.9; loss of Nkx2.9 leads to a reduction in Robo2 mRNA and protein within SACMNs and SACMN axons fail to exit the spinal cord in Robo2-deficient mice. Consistent with short-range interactions between Robo2 and Slit ligands regulating SACMN axon exit, Robo2-expressing SACMN axons normally navigate through LEP-associated Slits as they emerge from the spinal cord, and fail to exit in Slit-deficient mice. Our studies support the view that Nkx2.9 controls SACMN axon exit from the mammalian spinal cord by regulating Robo-Slit signaling.
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Affiliation(s)
- Arlene Bravo-Ambrosio
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Grant Mastick
- Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Zaven Kaprielian
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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35
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McCormick AM, Leipzig ND. Neural regenerative strategies incorporating biomolecular axon guidance signals. Ann Biomed Eng 2012; 40:578-97. [PMID: 22218702 DOI: 10.1007/s10439-011-0505-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 12/28/2011] [Indexed: 01/19/2023]
Abstract
There are currently no acceptable cures for central nervous system injuries, and damage induced large gaps in the peripheral nervous system have been challenging to bridge to restore neural functionality. Innervation by neurons is made possible by the growth cone. This dynamic structure is unique to neurons, and can directly sense physical and chemical activity in its environment, utilizing these cues to propel axons to precisely reach their targets. Guidance can occur through chemoattractive factors such as neurotrophins and netrins, chemorepulsive agents like semaphorins and slits, or contact-mediated molecules such as ephrins and those located in the extracellular matrix. The understanding of biomolecular activity during nervous system development and injury has generated new techniques and tactics for improving and restoring function to the nervous system after injury. This review will focus on the major neuronal guidance molecules and their utility in current tissue engineering and neural regenerative strategies.
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Affiliation(s)
- Aleesha M McCormick
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906, USA
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Croizier S, Amiot C, Chen X, Presse F, Nahon JL, Wu JY, Fellmann D, Risold PY. Development of posterior hypothalamic neurons enlightens a switch in the prosencephalic basic plan. PLoS One 2011; 6:e28574. [PMID: 22194855 PMCID: PMC3241628 DOI: 10.1371/journal.pone.0028574] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 11/10/2011] [Indexed: 12/24/2022] Open
Abstract
In rats and mice, ascending and descending axons from neurons producing melanin-concentrating hormone (MCH) reach the cerebral cortex and spinal cord. However, these ascending and descending projections originate from distinct sub-populations expressing or not “Cocaine-and-Amphetamine-Regulated-Transcript” (CART) peptide. Using a BrdU approach, MCH cell bodies are among the very first generated in the hypothalamus, within a longitudinal cell cord made of earliest delaminating neuroblasts in the diencephalon and extending from the chiasmatic region to the ventral midbrain. This region also specifically expresses the regulatory genes Sonic hedgehog (Shh) and Nkx2.2. First MCH axons run through the tractus postopticus (tpoc) which gathers pioneer axons from the cell cord and courses parallel to the Shh/Nkx2.2 expression domain. Subsequently generated MCH neurons and ascending MCH axons differentiate while neurogenesis and mantle layer differentiation are generalized in the prosencephalon, including telencephalon. Ascending MCH axons follow dopaminergic axons of the mesotelencephalic tract, both being an initial component of the medial forebrain bundle (mfb). Netrin1 and Slit2 proteins that are involved in the establishment of the tpoc and mfb, respectively attract or repulse MCH axons. We conclude that first generated MCH neurons develop in a diencephalic segment of a longitudinal Shh/Nkx2.2 domain. This region can be seen as a prosencephalic segment of a medial neurogenic column extending from the chiasmatic region through the ventral neural tube. However, as the telencephalon expends, it exerts a trophic action and the mfb expands, inducing a switch in the longitudinal axial organization of the prosencephalon.
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Affiliation(s)
- Sophie Croizier
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Clotilde Amiot
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Xiaoping Chen
- Department of Neurology, School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Françoise Presse
- UMR 6097 CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Nice-Sophia Antipolis, Valbonne, France
| | - Jean-Louis Nahon
- UMR 6097 CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Nice-Sophia Antipolis, Valbonne, France
| | - Jane Y. Wu
- Department of Neurology, School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Dominique Fellmann
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Pierre-Yves Risold
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
- * E-mail:
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Wilkinson AE, McCormick AM, Leipzig ND. Central Nervous System Tissue Engineering: Current Considerations and Strategies. ACTA ACUST UNITED AC 2011. [DOI: 10.2200/s00390ed1v01y201111tis008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Kim M, Roesener AP, Mendonca PRF, Mastick GS. Robo1 and Robo2 have distinct roles in pioneer longitudinal axon guidance. Dev Biol 2011; 358:181-8. [PMID: 21820427 PMCID: PMC3171630 DOI: 10.1016/j.ydbio.2011.07.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/16/2011] [Accepted: 07/16/2011] [Indexed: 11/16/2022]
Abstract
Pioneer longitudinal axons grow long distances parallel to the floor plate and precisely maintain their positions using guidance molecules released from the floor plate. Two receptors, Robo1 and Robo2, are critical for longitudinal axon guidance by the Slit family of chemorepellents. Previous studies showed that Robo1(-/-);2(-/-) double mutant mouse embryos have disruptions in both ventral and dorsal longitudinal tracts. However, the role of each Robo isoform remained unclear, because Robo1 or 2 single mutants have mild or no errors. Here we utilized a more sensitive genetic strategy to reduce Robo levels for determining any separate functions of the Robo1 and 2 isoforms. We found that Robo1 is the predominant receptor for guiding axons in ventral tracts and prevents midline crossing. In contrast, Robo2 is the main receptor for directing axons within dorsal tracts. Robo2 also has a distinct function in repelling neuron cell bodies from the floor plate. Therefore, while Robo1 and 2 have some genetic overlap to cooperate in guiding longitudinal axons, each isoform has distinct functions in specific longitudinal axon populations.
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Affiliation(s)
- Minkyung Kim
- Department of Biology, University of Nevada, Reno, USA
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Ricaño-Cornejo I, Altick AL, García-Peña CM, Nural HF, Echevarría D, Miquelajáuregui A, Mastick GS, Varela-Echavarría A. Slit-Robo signals regulate pioneer axon pathfinding of the tract of the postoptic commissure in the mammalian forebrain. J Neurosci Res 2011; 89:1531-41. [PMID: 21688288 PMCID: PMC4128405 DOI: 10.1002/jnr.22684] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 03/07/2011] [Accepted: 04/04/2011] [Indexed: 02/04/2023]
Abstract
During early vertebrate forebrain development, pioneer axons establish a symmetrical scaffold descending longitudinally through the rostral forebrain, thus forming the tract of the postoptic commissure (TPOC). In mouse embryos, this tract begins to appear at embryonic day 9.5 (E9.5) as a bundle of axons tightly constrained at a specific dorsoventral level. We have characterized the participation of the Slit chemorepellants and their Robo receptors in the control of TPOC axon projection. In E9.5-E11.5 mouse embryos, Robo1 and Robo2 are expressed in the nucleus origin of the TPOC (nTPOC), and Slit expression domains flank the TPOC trajectory. These findings suggested that these proteins are important factors in the dorsoventral positioning of the TPOC axons. Consistently with this role, Slit2 inhibited TPOC axon growth in collagen gel cultures, and interfering with Robo function in cultured embryos induced projection errors in TPOC axons. Moreover, absence of both Slit1 and Slit2 or Robo1 and Robo2 in mutant mouse embryos revealed aberrant TPOC trajectories, resulting in abnormal spreading of the tract and misprojections into both ventral and dorsal tissues. These results reveal that Slit-Robo signaling regulates the dorsoventral position of this pioneer tract in the developing forebrain.
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Affiliation(s)
- Itzel Ricaño-Cornejo
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
| | - Amy L. Altick
- Department of Biology, University of Nevada, Reno, Nevada
| | | | | | - Diego Echevarría
- Instituto de Neurociencias, Universidad Miguel Hernández, Alicante, Spain
| | - Amaya Miquelajáuregui
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
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Flores C. Role of netrin-1 in the organization and function of the mesocorticolimbic dopamine system. J Psychiatry Neurosci 2011; 36:296-310. [PMID: 21481303 PMCID: PMC3163646 DOI: 10.1503/jpn.100171] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Changes in mesocorticolimbic dopamine (DA) neurons and their target cells can be induced throughout life and are important determinants of individual differences in susceptibility to psychopathology. The goal of my research is to gain insight into the nature of the cellularand molecular mechanism underlying the selective plasticity of mesocorticolimbic DA neurons. Here, I review work showing that the guidance cue netrin-1 is implicated in the organization, plasticity and function of mesocorticolimbic DA neurons in rodents. Developmental variations in netrin-1 receptor function result in selective reorganization of medial prefrontal DA circuitry during adolescence and in an adult phenotype protected against schizophrenia-like dopaminergic and behavioural abnormalities. Furthermore, in adulthood, expression of netrin-1 receptors is upregulated by repeated exposure to stimulant drugs of abuse in DA somatodendritic regions and is necessary for drug-induced behavioural plasticity. I propose that risk factors associated with DA-related adult psychiatric disorders alter netrin-1 function.
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Affiliation(s)
- Cecilia Flores
- Department of Psychiatry, McGill University, Douglas Hospital Research Centre, Montréal, QC, Canada.
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Lmx1a and lmx1b function cooperatively to regulate proliferation, specification, and differentiation of midbrain dopaminergic progenitors. J Neurosci 2011; 31:12413-25. [PMID: 21880902 PMCID: PMC6703256 DOI: 10.1523/jneurosci.1077-11.2011] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
LIM homeodomain transcription factors, Lmx1a and Lmx1b, are required for the development of midbrain dopaminergic (mDA) neurons. Lmx1b is required for the specification and maintenance of mDA neurons, primarily due to its role in isthmic organizer development that is essential for the induction of mDA neurons. Here, we conditionally deleted Lmx1b in the ventral neural tube using ShhCre and found that Lmx1b conditional mutant mouse embryos show no defect in the development and maintenance of mDA neurons. In addition, Dreher (Lmx1a mutant) embryos display only a moderate reduction in the number of mDA neurons, suggesting that the related family member Lmx1b might compensate for Lmx1a function. We therefore generated Lmx1a and Lmx1b double mutants. Severe loss of mDA neurons occurred in Lmx1a(dr/dr);Shh(Cre/+);Lmx1b(f/f) double mutants due to essential roles for Lmx1a and Lmx1b in regulating the proliferation and neuronal commitment of mDA progenitors through the expression of Wnt1 and Ngn2, respectively. Lmx1a and Lmx1b also negatively regulate Hes1 expression and consequently cell cycle exit through activation of p27(Kip1) expression. In addition, Lmx1a and Lmx1b also regulate the expression of floor plate genes such as Corin and Slit2 and specification of postmitotic mDA neurons. These defects were more severe with decreasing gene dosage of Lmx1a and Lmx1b or observed only when all four copies of Lmx1a and Lmx1b genes were inactivated. Together, our results demonstrate that Lmx1a and Lmx1b function cooperatively to regulate proliferation, specification, and differentiation of mDA progenitors, including their floor plate-like properties.
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Abstract
AbstractThe olfactory system represents a perfect model to study the interactions between the central and peripheral nervous systems in order to establish a neural circuit during early embryonic development. In addition, another important feature of this system is the capability to integrate new cells generated in two neurogenic zones: the olfactory epithelium in the periphery and the wall of the lateral ventricles in the CNS, both during development and adulthood. In all these processes the combination and sequence of specific molecular signals plays a critical role in the wiring of the olfactory axons, as well as the precise location of the incoming cell populations to the olfactory bulb. The purpose of this review is to summarize recent insights into the cellular and molecular events that dictate cell settling position and axonal trajectories from their origin in the olfactory placode to the formation of synapses in the olfactory bulb to ensure rapid and reliable transmission of olfactory information from the nose to the brain.
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