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Reyes-Pinto R, Ferrán JL, Vega-Zuniga T, González-Cabrera C, Luksch H, Mpodozis J, Puelles L, Marín GJ. Change in the neurochemical signature and morphological development of the parvocellular isthmic projection to the avian tectum. J Comp Neurol 2021; 530:553-573. [PMID: 34363623 DOI: 10.1002/cne.25229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/27/2021] [Accepted: 07/30/2021] [Indexed: 11/05/2022]
Abstract
Neurons can change their classical neurotransmitters during ontogeny, sometimes going through stages of dual release. Here, we explored the development of the neurotransmitter identity of neurons of the avian nucleus isthmi parvocellularis (Ipc), whose axon terminals are retinotopically arranged in the optic tectum (TeO) and exert a focal gating effect upon the ascending transmission of retinal inputs. Although cholinergic and glutamatergic markers are both found in Ipc neurons and terminals of adult pigeons and chicks, the mRNA expression of the vesicular acetylcholine transporter, VAChT, is weak or absent. To explore how the Ipc neurotransmitter identity is established during ontogeny, we analyzed the expression of mRNAs coding for cholinergic (ChAT, VAChT, and CHT) and glutamatergic (VGluT2 and VGluT3) markers in chick embryos at different developmental stages. We found that between E12 and E18, Ipc neurons expressed all cholinergic mRNAs and also VGluT2 mRNA; however, from E16 through posthatch stages, VAChT mRNA expression was specifically diminished. Our ex vivo deposits of tracer crystals and intracellular filling experiments revealed that Ipc axons exhibit a mature paintbrush morphology late in development, experiencing marked morphological transformations during the period of presumptive dual vesicular transmitter release. Additionally, although ChAT protein immunoassays increasingly label the growing Ipc axon, this labeling was consistently restricted to sparse portions of the terminal branches. Combined, these results suggest that the synthesis of glutamate and acetylcholine, and their vesicular release, is complexly linked to the developmental processes of branching, growing and remodeling of these unique axons.
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Affiliation(s)
- Rosana Reyes-Pinto
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - José L Ferrán
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, University of Murcia, Murcia, Spain
| | - Tomas Vega-Zuniga
- Lehrstuhl für Zoologie, Technical University of Munich, Freising, Germany.,Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | | | - Harald Luksch
- Lehrstuhl für Zoologie, Technical University of Munich, Freising, Germany
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, University of Murcia, Murcia, Spain
| | - Gonzalo J Marín
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.,Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile
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Rapacioli M, Fiszer de Plazas S, Flores V. The developing optic tectum: An asymmetrically organized system and the need for a redefinition of the notion of sensitive period. Int J Dev Neurosci 2018; 73:1-9. [PMID: 30572015 DOI: 10.1016/j.ijdevneu.2018.12.003] [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: 11/03/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 10/27/2022] Open
Abstract
The present article summarizes the main events involved in the isthmic organizer and optic tectum determination and analyses how optic tectum patterning is translated, by the organized operation of several specific cell behaviors, into the terminally differentiated optic tectum. The paper proposes that this assembling of temporally/spatially organized cell behaviors could be incorporated into a wider notion of patterning and that, given the asymmetric organization of the developing optic tectum, the notion of "sensitive period" does not capture the whole complexity of midbrain development and the pathogenesis of congenital disorders. The cell behaviors involved in the optic tectum development are organized in time and space by the isthmic organizer. A comprehensive description of the normal optic tectum development, and also its alterations, should consider both domains. Significantly, the identity of each neuronal cohort depends critically on its "time and place of birth". Both parameters must be considered at once to explain how the structural and functional organization of the optic tectum is elaborated. The notion of "patterning" applies only to the early events of the optic tectum development. Besides, the notion of "sensitive period" considers only a temporal domain and disregards the asymmetric organization of the developing optic tectum. The present paper proposes that these notions might be re-defined: (a) a wider meaning of the term patterning and (b) a replacement of the term "sensitive period" by a more precise concept of "sensitive temporal/spatial window".
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Affiliation(s)
- Melina Rapacioli
- Grupo Interdisciplinario de Biología Teórica, Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Universidad Favaloro-INECO-CONICET, Buenos Aires, Argentina.
| | - Sara Fiszer de Plazas
- Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Vladimir Flores
- Grupo Interdisciplinario de Biología Teórica, Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Universidad Favaloro-INECO-CONICET, Buenos Aires, Argentina; Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
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Bogetti ME, Pozo Devoto VM, Rapacioli M, Flores V, Fiszer de Plazas S. NGF, TrkA-P and neuroprotection after a hypoxic event in the developing central nervous system. Int J Dev Neurosci 2018; 71:111-121. [PMID: 30165176 DOI: 10.1016/j.ijdevneu.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/20/2018] [Accepted: 08/22/2018] [Indexed: 11/30/2022] Open
Abstract
A decrease in the concentration of oxygen in the blood and tissues (hypoxia) produces important, sometimes irreversible, damages in the central nervous system (CNS) both during development and also postnatally. The present work aims at analyzing the expression of nerve growth factor (NGF) and p75 and the activation of TrkA in response to an acute normobaric hypoxic event and to evaluate the possible protective role of exogenous NGF. The developing chick optic tectum (OT), a recognized model of corticogenesis, was used as experimental system by means of in vivo and in vitro studies. Based on identification of the period of highest sensitivity of developmental programmed cell death (ED15) we show that hypoxia has a mild but reproducible effect that consist of a temporal increase of cell death 6 h after the end of a hypoxic treatment. Cell death was preceded by a significant early increase in the expression of Nerve Growth Factor (NGF) and its membrane receptor p75. In addition, we found a biphasic response of TrkA activation: a decrease during hypoxia followed by an increase -4 h later- that temporally coincide with the interval of NGF overexpression. To test the NGF - NGF receptors role in hypoxic cell death, we quantified, in primary neuronal cultures derived from ED15 OT, the levels of TrkA activation after an acute hypoxic treatment. A significant decline in the level of TrkA activation was observed during hypoxia followed, 24 h later, by significant cell death. Interestingly, this cell death can be reverted if TrkA inactivation during hypoxia is suppressed by the addition of NGF. Our results suggest that TrkA activation may play an important role in the survival of OT neurons subjected to acute hypoxia. The role of TrkA in neuronal survival after injury may be advantageously used for the generation of neuroprotective strategies to improve prenatal insult outcomes.
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Affiliation(s)
- María Eugenia Bogetti
- Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Victorio M Pozo Devoto
- Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Melina Rapacioli
- Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Universidad Favaloro-INECO-CONICET, Buenos Aires, Argentina
| | - Vladimir Flores
- Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina; Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Universidad Favaloro-INECO-CONICET, Buenos Aires, Argentina
| | - Sara Fiszer de Plazas
- Instituto de Biología Celular y Neurociencias (IBCN) Dr. Eduardo de Robertis, Facultad de Medicina, CONICET, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina.
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Rapacioli M, Palma V, Flores V. Morphogenetic and Histogenetic Roles of the Temporal-Spatial Organization of Cell Proliferation in the Vertebrate Corticogenesis as Revealed by Inter-specific Analyses of the Optic Tectum Cortex Development. Front Cell Neurosci 2016; 10:67. [PMID: 27013978 PMCID: PMC4794495 DOI: 10.3389/fncel.2016.00067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/01/2016] [Indexed: 12/11/2022] Open
Abstract
The central nervous system areas displaying the highest structural and functional complexity correspond to the so called cortices, i.e., concentric alternating neuronal and fibrous layers. Corticogenesis, i.e., the development of the cortical organization, depends on the temporal-spatial organization of several developmental events: (a) the duration of the proliferative phase of the neuroepithelium, (b) the relative duration of symmetric (expansive) versus asymmetric (neuronogenic) sub phases, (c) the spatial organization of each kind of cell division, (e) the time of determination and cell cycle exit and (f) the time of onset of the post-mitotic neuronal migration and (g) the time of onset of the neuronal structural and functional differentiation. The first five events depend on molecular mechanisms that perform a fine tuning of the proliferative activity. Changes in any of them significantly influence the cortical size or volume (tangential expansion and radial thickness), morphology, architecture and also impact on neuritogenesis and synaptogenesis affecting the cortical wiring. This paper integrates information, obtained in several species, on the developmental roles of cell proliferation in the development of the optic tectum (OT) cortex, a multilayered associative area of the dorsal (alar) midbrain. The present review (1) compiles relevant information on the temporal and spatial organization of cell proliferation in different species (fish, amphibians, birds, and mammals), (2) revises the main molecular events involved in the isthmic organizer (IsO) determination and localization, (3) describes how the patterning installed by IsO is translated into spatially organized neural stem cell proliferation (i.e., by means of growth factors, receptors, transcription factors, signaling pathways, etc.) and (4) describes the morpho- and histogenetic effect of a spatially organized cell proliferation in the above mentioned species. A brief section on the OT evolution is also included. This section considers how the differential operation of cell proliferation could explain differences among species.
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Affiliation(s)
- Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Department of Biostructural Sciences, Favaloro UniversityBuenos Aires, Argentina
| | - Verónica Palma
- Laboratory of Stem Cell and Developmental Biology, Faculty of Science, University of ChileSantiago, Chile
| | - Vladimir Flores
- Interdisciplinary Group in Theoretical Biology, Department of Biostructural Sciences, Favaloro UniversityBuenos Aires, Argentina
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Celin AR, Rapacioli M, Gonzalez MA, Ballarin VL, de Plazas SF, López-Costa JJ, Flores V. Temporal-spatial correlation between angiogenesis and corticogenesis in the developing chick optic tectum. PLoS One 2015; 10:e0116343. [PMID: 25633659 PMCID: PMC4310613 DOI: 10.1371/journal.pone.0116343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 12/05/2014] [Indexed: 01/02/2023] Open
Abstract
The developing chick optic tectum is a widely used model of corticogenesis and angiogenesis. Cell behaviors involved in corticogenesis and angiogenesis share several regulatory mechanisms. In this way the 3D organizations of both systems adapt to each other. The consensus about the temporally and spatially organized progression of the optic tectum corticogenesis contrasts with the discrepancies about the spatial organization of its vascular bed as a function of the time. In order to find out spatial and temporal correlations between corticogenesis and angiogenesis, several methodological approaches were applied to analyze the dynamic of angiogenesis in the developing chick optic tectum. The present paper shows that a typical sequence of developmental events characterizes the optic tectum angiogenesis. The first phase, formation of the primitive vascular bed, takes place during the early stages of the tectal corticogenesis along which the large efferent neurons appear and begin their early differentiation. The second phase, remodeling and elaboration of the definitive vascular bed, occurs during the increase in complexity associated to the elaboration of the local circuit networks. The present results show that, apart from the well-known influence of the dorsal-ventral and radial axes as reference systems for the spatial organization of optic tectum angiogenesis, the cephalic-caudal axis also exerts a significant asymmetric influence. The term cortico-angiogenesis to describe the entire process is justified by the fact that tight correlations are found between specific corticogenic and angiogenic events and they take place simultaneously at the same position along the cephalic-caudal and radial axes.
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Affiliation(s)
- Alejandra Rodriguez Celin
- Interdisciplinary Group in Theoretical Biology, Dep. Biostructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Dep. Biostructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Mariela Azul Gonzalez
- Digital Image Processing Group, School of Engineering, National University of Mar del Plata, Mar del Plata, Argentina
| | - Virginia Laura Ballarin
- Digital Image Processing Group, School of Engineering, National University of Mar del Plata, Mar del Plata, Argentina
| | - Sara Fiszer de Plazas
- Institute of Cell Biology and Neurosciences “Prof. E. De Robertis”; Buenos Aires University-CONICET, Buenos Aires, Argentina
| | - Juan José López-Costa
- Institute of Cell Biology and Neurosciences “Prof. E. De Robertis”; Buenos Aires University-CONICET, Buenos Aires, Argentina
| | - Vladimir Flores
- Interdisciplinary Group in Theoretical Biology, Dep. Biostructural Sciences, Favaloro University, Buenos Aires, Argentina
- Institute of Cell Biology and Neurosciences “Prof. E. De Robertis”; Buenos Aires University-CONICET, Buenos Aires, Argentina
- * E-mail:
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Lino N, Fiore L, Rapacioli M, Teruel L, Flores V, Scicolone G, Sánchez V. uPA-uPAR molecular complex is involved in cell signaling during neuronal migration and neuritogenesis. Dev Dyn 2014; 243:676-89. [PMID: 24481918 DOI: 10.1002/dvdy.24114] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND In the development of the central nervous system (CNS), neuronal migration and neuritogenesis are crucial processes for establishing functional neural circuits. This relies on the regulation exerted by several signaling molecules, which play important roles in axonal growth and guidance. The urokinase-type plasminogen activator (uPA)-in association with its receptor-triggers extracellular matrix proteolysis and other cellular processes through the activation of intracellular signaling pathways. Even though the uPA-uPAR complex is well characterized in nonneuronal systems, little is known about its signaling role during CNS development. RESULTS In response to uPA, neuronal migration and neuritogenesis are promoted in a dose-dependent manner. After stimulation, uPAR interacts with α5- and β1-integrin subunits, which may constitute an αβ-heterodimer that acts as a uPA-uPAR coreceptor favoring the activation of multiple kinases. This interaction may be responsible for the uPA-promoted phosphorylation of focal adhesion kinase (FAK) and its relocation toward growth cones, triggering cytoskeletal reorganization which, in turn, induces morphological changes related to neuronal migration and neuritogenesis. CONCLUSIONS uPA has a key role during CNS development. In association with its receptor, it orchestrates both proteolytic and nonproteolytic events that govern the proper formation of neural networks.
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Affiliation(s)
- Noelia Lino
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences "Prof. E. De Robertis" (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
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Lever M, Brand-Saberi B, Theiss C. Neurogenesis, gliogenesis and the developing chicken optic tectum: an immunohistochemical and ultrastructural analysis. Brain Struct Funct 2013; 219:1009-24. [DOI: 10.1007/s00429-013-0550-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/25/2013] [Indexed: 12/16/2022]
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Rapacioli M, Botelho J, Cerda G, Duarte S, Elliot M, Palma V, Flores V. Sonic hedgehog (Shh)/Gli modulates the spatial organization of neuroepithelial cell proliferation in the developing chick optic tectum. BMC Neurosci 2012. [PMID: 23031710 DOI: 10.1186/1471‐2202‐13‐117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sonic hedgehog (Shh)/Gli pathway plays an important regulatory role on the neuroepithelial cells (NEc) proliferation in the dorsal regions of the developing vertebrate Central Nervous System. The aim of this paper was to analyze the effect of the Shh/Gli signaling pathway activation on the proliferation dynamics and/or the spatial organization of the NEc proliferation activity during early stages of the developing chick optic tectum (OT). In ovo pharmacological gain and loss of hedgehog function approaches were complemented with in vivo electroporation experiments in order to create ectopic sources of either Shh or Gli activator (GliA) proteins in the OT. NEc proliferating activity was analyzed at ED 4/4.5 by recording the spatial co-ordinates of the entire population of mitotic NEc (mNEc) located along OT dorsal-ventral sections. Several space signals (numerical sequences) were derived from the mNEc spatial co-ordinate records and analyzed by different standardized non-linear methods of signal analysis. RESULTS In ovo pharmacologic treatment with cyclopamine resulted in dramatic failure in the OT expansion while the agonist purmorphamine produced the opposite result, a huge expansion of the OT vesicle. Besides, GliA and Shh misexpressions interfere with the formation of the intertectal fissure located along the dorsal midline. This morphogenetic alteration is accompanied by an increase in the mNEc density. There is a gradient in the response of NEcs to Shh and GliA: the increase in mNEc density is maximal near the dorsal regions and decrease towards the OT-tegmental boundary. Biomathematical analyses of the signals derived from the mNEc records show that both Shh and GliA electroporations change the proliferation dynamics and the spatial organization of the mNEc as revealed by the changes in the scaling index estimated by these methods. CONCLUSIONS The present results show that the Shh/Gli signaling pathway plays a critical role in the OT expansion and modelling. This effect is probably mediated by a differential mitogenic effect that increases the NEc proliferation and modulates the spatial organization of the NEc proliferation activity.
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Affiliation(s)
- Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Department Biostructural Sciences, Favaloro University, Solís 453 (1078), Buenos Aires, Argentina
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Rapacioli M, Botelho J, Cerda G, Duarte S, Elliot M, Palma V, Flores V. Sonic hedgehog (Shh)/Gli modulates the spatial organization of neuroepithelial cell proliferation in the developing chick optic tectum. BMC Neurosci 2012; 13:117. [PMID: 23031710 PMCID: PMC3564940 DOI: 10.1186/1471-2202-13-117] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 09/26/2012] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Sonic hedgehog (Shh)/Gli pathway plays an important regulatory role on the neuroepithelial cells (NEc) proliferation in the dorsal regions of the developing vertebrate Central Nervous System. The aim of this paper was to analyze the effect of the Shh/Gli signaling pathway activation on the proliferation dynamics and/or the spatial organization of the NEc proliferation activity during early stages of the developing chick optic tectum (OT). In ovo pharmacological gain and loss of hedgehog function approaches were complemented with in vivo electroporation experiments in order to create ectopic sources of either Shh or Gli activator (GliA) proteins in the OT. NEc proliferating activity was analyzed at ED 4/4.5 by recording the spatial co-ordinates of the entire population of mitotic NEc (mNEc) located along OT dorsal-ventral sections. Several space signals (numerical sequences) were derived from the mNEc spatial co-ordinate records and analyzed by different standardized non-linear methods of signal analysis. RESULTS In ovo pharmacologic treatment with cyclopamine resulted in dramatic failure in the OT expansion while the agonist purmorphamine produced the opposite result, a huge expansion of the OT vesicle. Besides, GliA and Shh misexpressions interfere with the formation of the intertectal fissure located along the dorsal midline. This morphogenetic alteration is accompanied by an increase in the mNEc density. There is a gradient in the response of NEcs to Shh and GliA: the increase in mNEc density is maximal near the dorsal regions and decrease towards the OT-tegmental boundary. Biomathematical analyses of the signals derived from the mNEc records show that both Shh and GliA electroporations change the proliferation dynamics and the spatial organization of the mNEc as revealed by the changes in the scaling index estimated by these methods. CONCLUSIONS The present results show that the Shh/Gli signaling pathway plays a critical role in the OT expansion and modelling. This effect is probably mediated by a differential mitogenic effect that increases the NEc proliferation and modulates the spatial organization of the NEc proliferation activity.
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Affiliation(s)
- Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Department Biostructural Sciences, Favaloro University, Solís 453 (1078), Buenos Aires, Argentina
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Geysens S, Ferran JL, Van Herck SLJ, Tylzanowski P, Puelles L, Darras VM. Dynamic mRNA distribution pattern of thyroid hormone transporters and deiodinases during early embryonic chicken brain development. Neuroscience 2012; 221:69-85. [PMID: 22771619 DOI: 10.1016/j.neuroscience.2012.06.057] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/18/2012] [Accepted: 06/26/2012] [Indexed: 01/03/2023]
Abstract
Maternal thyroid hormones (THs) are important in early brain development long before the onset of embryonic TH secretion, but information about the regulation of TH availability in the brain at these early stages is still limited. We therefore investigated in detail the mRNA distribution pattern of the TH activating type 2 and inactivating type 3 deiodinases (D2 and D3) and the TH transporters, organic anion transporting polypeptide 1c1 (Oatp1c1) and monocarboxylate transporter 8 (Mct8), in chicken embryonic brain as well as in retina and inner ear from day 3 to day 10 of development. Oatp1c1, Mct8 and D3 are expressed in the choroid plexus and its precursors allowing selective uptake of THs at the blood-cerebrospinal fluid-barrier with subsequent inactivation of excess hormone. In contrast, the developing blood-brain-barrier does not express Oatp1c1 or Mct8 but appears to be a site for TH activation by D2. Expression of D3 in several sensory brain centers may serve as protection against premature TH action. Expression of D2 and Mct8 but not D3 in the developing pituitary gland allows accumulation of active THs even at early stages. Mct8 is widely expressed in gray matter throughout the brain. This is the first comprehensive study on the dynamic distribution pattern of TH-transporters and deiodinases at stages of embryonic brain development when only maternal THs are available. It provides the essential background for further research aimed at understanding early developmental processes depending on maternal THs.
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Affiliation(s)
- S Geysens
- Laboratory of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, B-3000 Leuven, Belgium
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Ortalli AL, Fiore L, Di Napoli J, Rapacioli M, Salierno M, Etchenique R, Flores V, Sanchez V, Carri NG, Scicolone G. EphA3 expressed in the chicken tectum stimulates nasal retinal ganglion cell axon growth and is required for retinotectal topographic map formation. PLoS One 2012; 7:e38566. [PMID: 22685584 PMCID: PMC3369860 DOI: 10.1371/journal.pone.0038566] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 05/07/2012] [Indexed: 11/29/2022] Open
Abstract
Background Retinotopic projection onto the tectum/colliculus constitutes the most studied model of topographic mapping and Eph receptors and their ligands, the ephrins, are the best characterized molecular system involved in this process. Ephrin-As, expressed in an increasing rostro-caudal gradient in the tectum/colliculus, repel temporal retinal ganglion cell (RGC) axons from the caudal tectum and inhibit their branching posterior to their termination zones. However, there are conflicting data regarding the nature of the second force that guides nasal axons to invade and branch only in the caudal tectum/colliculus. The predominant model postulates that this second force is produced by a decreasing rostro-caudal gradient of EphA7 which repels nasal optic fibers and prevents their branching in the rostral tectum/colliculus. However, as optic fibers invade the tectum/colliculus growing throughout this gradient, this model cannot explain how the axons grow throughout this repellent molecule. Methodology/Principal Findings By using chicken retinal cultures we showed that EphA3 ectodomain stimulates nasal RGC axon growth in a concentration dependent way. Moreover, we showed that nasal axons choose growing on EphA3-expressing cells and that EphA3 diminishes the density of interstitial filopodia in nasal RGC axons. Accordingly, in vivo EphA3 ectodomain misexpression directs nasal optic fibers toward the caudal tectum preventing their branching in the rostral tectum. Conclusions We demonstrated in vitro and in vivo that EphA3 ectodomain (which is expressed in a decreasing rostro-caudal gradient in the tectum) is necessary for topographic mapping by stimulating the nasal axon growth toward the caudal tectum and inhibiting their branching in the rostral tectum. Furthermore, the ability of EphA3 of stimulating axon growth allows understanding how optic fibers invade the tectum growing throughout this molecular gradient. Therefore, opposing tectal gradients of repellent ephrin-As and of axon growth stimulating EphA3 complement each other to map optic fibers along the rostro-caudal tectal axis.
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Affiliation(s)
- Ana Laura Ortalli
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Luciano Fiore
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Jennifer Di Napoli
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Department of Bioestructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Marcelo Salierno
- Department of Inorganic, Analytical and Physical Chemistry (INQUIMAE), Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina
| | - Roberto Etchenique
- Department of Inorganic, Analytical and Physical Chemistry (INQUIMAE), Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina
| | - Vladimir Flores
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
- Interdisciplinary Group in Theoretical Biology, Department of Bioestructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Viviana Sanchez
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | | | - Gabriel Scicolone
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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Rapacioli M, Duarte S, Rodríguez Celín A, Fiore L, Teruel L, Scicolone G, Sánchez V, Flores V. Optic tectum morphogenesis: A step-by-step model based on the temporal-spatial organization of the cell proliferation. Significance of deterministic and stochastic components subsumed in the spatial organization. Dev Dyn 2012; 241:1043-61. [DOI: 10.1002/dvdy.23785] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2012] [Indexed: 12/17/2022] Open
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