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Chen M, Xu L, Wu Y, Soba P, Hu C. The organization and function of the Golgi apparatus in dendrite development and neurological disorders. Genes Dis 2023; 10:2425-2442. [PMID: 37554209 PMCID: PMC10404969 DOI: 10.1016/j.gendis.2022.11.009] [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: 07/04/2022] [Revised: 09/13/2022] [Accepted: 11/05/2022] [Indexed: 12/24/2022] Open
Abstract
Dendrites are specialized neuronal compartments that sense, integrate and transfer information in the neural network. Their development is tightly controlled and abnormal dendrite morphogenesis is strongly linked to neurological disorders. While dendritic morphology ranges from relatively simple to extremely complex for a specified neuron, either requires a functional secretory pathway to continually replenish proteins and lipids to meet dendritic growth demands. The Golgi apparatus occupies the center of the secretory pathway and is regulating posttranslational modifications, sorting, transport, and signal transduction, as well as acting as a non-centrosomal microtubule organization center. The neuronal Golgi apparatus shares common features with Golgi in other eukaryotic cell types but also forms distinct structures known as Golgi outposts that specifically localize in dendrites. However, the organization and function of Golgi in dendrite development and its impact on neurological disorders is just emerging and so far lacks a systematic summary. We describe the organization of the Golgi apparatus in neurons, review the current understanding of Golgi function in dendritic morphogenesis, and discuss the current challenges and future directions.
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Affiliation(s)
- Meilan Chen
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Lu Xu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
| | - Yi Wu
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Peter Soba
- LIMES Institute, Department of Molecular Brain Physiology and Behavior, University of Bonn, Bonn 53115, Germany
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Chun Hu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
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Enck JR, Olson EC. Calcium Signaling during Cortical Apical Dendrite Initiation: A Role for Cajal-Retzius Neurons. Int J Mol Sci 2023; 24:12965. [PMID: 37629145 PMCID: PMC10455361 DOI: 10.3390/ijms241612965] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
The apical dendrite of a cortical projection neuron (CPN) is generated from the leading process of the migrating neuron as the neuron completes migration. This transformation occurs in the cortical marginal zone (MZ), a layer that contains the Cajal-Retzius neurons and their axonal projections. Cajal-Retzius neurons (CRNs) are well known for their critical role in secreting Reelin, a glycoprotein that controls dendritogenesis and cell positioning in many regions of the developing brain. In this study, we examine the possibility that CRNs in the MZ may provide additional signals to arriving CPNs, that may promote the maturation of CPNs and thus shape the development of the cortex. We use whole embryonic hemisphere explants and multiphoton microscopy to confirm that CRNs display intracellular calcium transients of <1-min duration and high amplitude during early corticogenesis. In contrast, developing CPNs do not show high-amplitude calcium transients, but instead show a steady increase in intracellular calcium that begins at the time of dendritic initiation, when the leading process of the migrating CPN is encountering the MZ. The possible existence of CRN to CPN communication was revealed by the application of veratridine, a sodium channel activator, which has been shown to preferentially stimulate more mature cells in the MZ at an early developmental time. Surprisingly, veratridine application also triggers large calcium transients in CPNs, which can be partially blocked by a cocktail of antagonists that block glutamate and glycine receptor activation. These findings outline a model in which CRN spontaneous activity triggers the release of glutamate and glycine, neurotransmitters that can trigger intracellular calcium elevations in CPNs. These elevations begin as CPNs initiate dendritogenesis and continue as waves in the post-migratory cells. Moreover, we show that the pharmacological blockade of glutamatergic signaling disrupts migration, while forced expression of a bacterial voltage-gated calcium channel (CavMr) in the migrating neurons promotes dendritic growth and migration arrest. The identification of CRN to CPN signaling during early development provides insight into the observation that many autism-linked genes encode synaptic proteins that, paradoxically, are expressed in the developing cortex well before the appearance of synapses and the establishment of functional circuits.
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Affiliation(s)
| | - Eric C. Olson
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, 505 Irving Ave., Syracuse, NY 13210, USA;
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3
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Useinovic N, Near M, Cabrera OH, Boscolo A, Milosevic A, Harvey R, Newson A, Chastain-Potts S, Quillinan N, Jevtovic-Todorovic V. Neonatal sevoflurane exposure induces long-term changes in dendritic morphology in juvenile rats and mice. Exp Biol Med (Maywood) 2023; 248:641-655. [PMID: 37309741 PMCID: PMC10350807 DOI: 10.1177/15353702231170003] [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: 02/10/2023] [Accepted: 03/11/2023] [Indexed: 06/14/2023] Open
Abstract
General anesthetics are potent neurotoxins when given during early development, causing apoptotic deletion of substantial number of neurons and persistent neurocognitive and behavioral deficits in animals and humans. The period of intense synaptogenesis coincides with the peak of susceptibility to deleterious effects of anesthetics, a phenomenon particularly pronounced in vulnerable brain regions such as subiculum. With steadily accumulating evidence confirming that clinical doses and durations of anesthetics may permanently alter the physiological trajectory of brain development, we set out to investigate the long-term consequences on dendritic morphology of subicular pyramidal neurons and expression on genes regulating the complex neural processes such as neuronal connectivity, learning, and memory. Using a well-established model of anesthetic neurotoxicity in rats and mice neonatally exposed to sevoflurane, a volatile general anesthetic commonly used in pediatric anesthesia, we report that a single 6 h of continuous anesthesia administered at postnatal day (PND) 7 resulted in lasting dysregulation in subicular mRNA levels of cAMP responsive element modulator (Crem), cAMP responsive element-binding protein 1 (Creb1), and Protein phosphatase 3 catalytic subunit alpha, a subunit of calcineurin (Ppp3ca) (calcineurin) when examined during juvenile period at PND28. Given the critical role of these genes in synaptic development and neuronal plasticity, we deployed a set of histological measurements to investigate the implications of anesthesia-induced dysregulation of gene expression on morphology and complexity of surviving subicular pyramidal neurons. Our results indicate that neonatal exposure to sevoflurane induced lasting rearrangement of subicular dendrites, resulting in higher orders of complexity and increased branching with no significant effects on the soma of pyramidal neurons. Correspondingly, changes in dendritic complexity were paralleled by the increased spine density on apical dendrites, further highlighting the scope of anesthesia-induced dysregulation of synaptic development. We conclude that neonatal sevoflurane induced persistent genetic and morphological dysregulation in juvenile rodents, which could indicate heightened susceptibility toward cognitive and behavioral disorders we are beginning to recognize as sequelae of early-in-life anesthesia.
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Affiliation(s)
- Nemanja Useinovic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Michelle Near
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Omar Hoseá Cabrera
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Annalisa Boscolo
- Institute of Anesthesia and Intensive Care, Padua University Hospital, Padua 35128. Italy
- Department of Medicine (DIMED), University of Padua, Padua 35128, Italy
| | - Andjelko Milosevic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Rachel Harvey
- Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
| | - Adre Newson
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Shelby Chastain-Potts
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Nidia Quillinan
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Neuronal Injury and Plasticity Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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4
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Maternal Ethanol Exposure Acutely Elevates Src Family Kinase Activity in the Fetal Cortex. Mol Neurobiol 2021; 58:5210-5223. [PMID: 34272687 PMCID: PMC8497457 DOI: 10.1007/s12035-021-02467-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/20/2021] [Indexed: 11/24/2022]
Abstract
Fetal alcohol syndrome (FAS) is characterized by disrupted fetal brain development and postnatal cognitive impairment. The targets of alcohol are diverse, and it is not clear whether there are common underlying molecular mechanisms producing these disruptions. Prior work established that acute ethanol exposure causes a transient increase in tyrosine phosphorylation of multiple proteins in cultured embryonic cortical cells. In this study, we show that a similar tyrosine phosphorylation transient occurs in the fetal brain after maternal dosing with ethanol. Using phospho-specific antibodies and immunohistochemistry, we mapped regions of highest tyrosine phosphorylation in the fetal cerebral cortex and found that areas of dendritic and axonal growth showed elevated tyrosine phosphorylation 10 min after maternal ethanol exposure. These were also areas of Src expression and Src family kinase (SFK) activation loop phosphorylation (pY416) expression. Importantly, maternal pretreatment with the SFK inhibitor dasatinib completely prevents both the pY416 increase and the tyrosine phosphorylation response. The phosphorylation response was observed in the perisomatic region and neurites of immature migrating and differentiating primary neurons. Importantly, the initial phosphotyrosine transient (~ 30 min) targets both Src and Dab1, two critical elements in Reelin signaling, a pathway required for normal cortical development. This initial phosphorylation response is followed by sustained reduction in Ser3 phosphorylation of n-cofilin, a critical actin severing protein and an identified downstream effector of Reelin signaling. This biochemical disruption is associated with sustained reduction of F-actin content and disrupted Golgi apparatus morphology in developing cortical neurons. The finding outlines a model in which the initial activation of SFKs by ethanol has the potential to disrupt multiple developmentally important signaling systems for several hours after maternal exposure.
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Fujii C, Zorumski CF, Izumi Y. Ethanol, neurosteroids and cellular stress responses: Impact on central nervous system toxicity, inflammation and autophagy. Neurosci Biobehav Rev 2021; 124:168-178. [PMID: 33561510 DOI: 10.1016/j.neubiorev.2021.01.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 01/19/2021] [Indexed: 01/21/2023]
Abstract
Alcohol intake can impair brain function, in addition to other organs such as the liver and kidney. In the brain ethanol can be detrimental to memory formation, through inducing the integrated stress response/endoplasmic reticulum stress/unfolded protein response and the molecular mechanisms linking stress to other events such as NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammation and autophagy. This literature review aims to provide an overview of our current understanding of the molecular mechanisms involved in ethanol-induced damage with endoplasmic reticulum stress, integrated stress response, NLRP3 inflammation and autophagy, while discussing the impact of neurosteroids and oxysterols, including allopregnanolone, 25-hydroxycholesterol and 24S-hydroxycholesterol, on the central nervous system.
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Affiliation(s)
- Chika Fujii
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, United States
| | - Charles F Zorumski
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, United States
| | - Yukitoshi Izumi
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, United States.
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Bogenpohl JW, Smith ML, Farris SP, Dumur CI, Lopez MF, Becker HC, Grant KA, Miles MF. Cross-Species Co-analysis of Prefrontal Cortex Chronic Ethanol Transcriptome Responses in Mice and Monkeys. Front Mol Neurosci 2019; 12:197. [PMID: 31456662 PMCID: PMC6701453 DOI: 10.3389/fnmol.2019.00197] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/30/2019] [Indexed: 12/20/2022] Open
Abstract
Despite recent extensive genomic and genetic studies on behavioral responses to ethanol, relatively few new therapeutic targets for the treatment of alcohol use disorder have been validated. Here, we describe a cross-species genomic approach focused on identifying gene networks associated with chronic ethanol consumption. To identify brain mechanisms underlying a chronic ethanol consumption phenotype highly relevant to human alcohol use disorder, and to elucidate potential future therapeutic targets, we conducted a genomic study in a non-human primate model of chronic open-access ethanol consumption. Microarray analysis of RNA expression in anterior cingulate and subgenual cortices from rhesus macaques was performed across multiple cohorts of animals. Gene networks correlating with ethanol consumption or showing enrichment for ethanol-regulated genes were identified, as were major ethanol-related hub genes within these networks. A subsequent consensus module analysis was used to co-analyze monkey data with expression data from a chronic intermittent ethanol vapor-exposure and consumption model in C57BL/6J mice. Ethanol-related gene networks conserved between primates and rodents were enriched for genes involved in discrete biological functions, including; myelination, synaptic transmission, chromatin modification, Golgi apparatus function, translation, cellular respiration, and RNA processing. The myelin-related network, in particular, showed strong correlations with ethanol consumption behavior and displayed marked network reorganization between control and ethanol-drinking animals. Further bioinformatics analysis revealed that these networks also showed highly significant overlap with other ethanol-regulated gene sets. Altogether, these studies provide robust primate and rodent cross-species validation of gene networks associated with chronic ethanol consumption. Our results also suggest potential novel focal points for future therapeutic interventions in alcohol use disorder.
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Affiliation(s)
- James W Bogenpohl
- Department of Molecular Biology and Chemistry, Christopher Newport University, Newport News, VA, United States
| | - Maren L Smith
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States
| | - Sean P Farris
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX, United States
| | - Catherine I Dumur
- Aurora Diagnostics-Sonic Healthcare, Bernhardt Laboratories, Jacksonville, FL, United States
| | - Marcelo F Lopez
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Howard C Becker
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Kathleen A Grant
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, United States.,Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, United States
| | - Michael F Miles
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States.,Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States.,Department of Neurology, Virginia Commonwealth University, Richmond, VA, United States.,VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, VA, United States
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7
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Gano A, Vore AS, Sammakia M, Deak T. Assessment of Extracellular Cytokines in the Hippocampus of the Awake Behaving Rat Using Large-Molecule Microdialysis Combined with Multiplex Arrays After Acute and Chronic Ethanol Exposure. Alcohol Clin Exp Res 2019; 43:640-654. [PMID: 30667526 PMCID: PMC6443416 DOI: 10.1111/acer.13963] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/14/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Studies have demonstrated persistent changes in central nervous system (CNS) cytokine gene expression following ethanol (EtOH) exposure. However, the low endogenous expression and short half-lives of cytokines in the CNS have made cytokine protein detection challenging. The goal of these studies was to establish parameters for use of large-molecule microdialysis and sensitive multiplexing technology for the simultaneous detection of brain cytokines, corticosterone (CORT), and EtOH concentrations in the awake behaving rat. METHODS Adult (P75+) male Sprague Dawley rats that were either naïve to EtOH (Experiment 1) or had a history of adolescent chronic intermittent EtOH (CIE; Experiment 2) were given an acute EtOH challenge during microdialysis. Experiment 1 examined brain EtOH concentrations, CORT and a panel of neuroimmune analytes, including cytokines associated with innate and adaptive immunity. The natural time course of changes in these cytokines was compared to the effects of an acute 1.5 or 3.0 g/kg intraperitoneal (i.p.) EtOH challenge. In Experiment 2, rats with a history of adolescent CIE or controls exposed to vehicle were challenged with 3.0 g/kg i.p. EtOH during microdialysis in adulthood, and a panel of cytokines was examined in parallel with brain EtOH concentrations and CORT. RESULTS The microdialysis procedure itself induced a cytokine-specific response that replicated across studies, specifically a sequential elevation of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-10. Surprisingly, acute EtOH did not significantly alter this course of cytokine fluctuations in the hippocampus. However, a history of adolescent CIE showed drastic effects on multiple neuroimmune analytes when rechallenged with EtOH as adults. Rats with a history of adolescent EtOH displayed a severely blunted neuroimmune response in adulthood, evinced by suppressed IL-1β, IL-10, and TNF-α. CONCLUSIONS Together, these findings provide a methodological framework for assessment of cytokine release patterns, their modulation by EtOH, and the long-lasting changes to neuroimmune reactivity evoked by a history of adolescent CIE.
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Affiliation(s)
- Anny Gano
- Medical University of South Carolina, Charleston Alcohol Research Center, Charleston, SC, USA
| | - Andrew S. Vore
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton NY 13902-6000
| | - Maryam Sammakia
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton NY 13902-6000
| | - Terrence Deak
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton NY 13902-6000
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8
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Wang D, Enck J, Howell BW, Olson EC. Ethanol Exposure Transiently Elevates but Persistently Inhibits Tyrosine Kinase Activity and Impairs the Growth of the Nascent Apical Dendrite. Mol Neurobiol 2019; 56:5749-5762. [PMID: 30674037 DOI: 10.1007/s12035-019-1473-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/10/2019] [Indexed: 12/11/2022]
Abstract
Dendritogenesis can be impaired by exposure to alcohol, and aspects of this impairment share phenotypic similarities to dendritic defects observed after blockade of the Reelin-Dab1 tyrosine kinase signaling pathway. In this study, we find that 10 min of alcohol exposure (400 mg/dL ethanol) by itself causes an unexpected increase in tyrosine phosphorylation of many proteins including Src and Dab1 that are essential downstream effectors of Reelin signaling. This increase in phosphotyrosine is dose-dependent and blockable by selective inhibitors of Src Family Kinases (SFKs). However, the response is transient, and phosphotyrosine levels return to baseline after 30 min of continuous ethanol exposure, both in vitro and in vivo. During this latter period, Src is inactivated and Reelin application cannot stimulate Dab1 phosphorylation. This suggests that ethanol initially activates but then silences the Reelin-Dab1 signaling pathway by brief activation and then sustained inactivation of SFKs. Time-lapse analyses of dendritic growth dynamics show an overall decrease in growth and branching compared to controls after ethanol-exposure that is similar to that observed with Reelin-deficiency. However, unlike Reelin-signaling disruptions, the dendritic filopodial speeds are decreased after ethanol exposure, and this decrease is associated with sustained dephosphorylation and activation of cofilin, an F-actin severing protein. These findings suggest that persistent Src inactivation coupled to cofilin activation may contribute to the dendritic disruptions observed with fetal alcohol exposure.
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Affiliation(s)
- Dandan Wang
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 505 Irving Ave, Syracuse, NY, 13210, USA.,Developmental Exposure to Alcohol Research Center (DEARC), Binghamton University, Binghamton, NY, 13902, USA
| | - Joshua Enck
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 505 Irving Ave, Syracuse, NY, 13210, USA.,Developmental Exposure to Alcohol Research Center (DEARC), Binghamton University, Binghamton, NY, 13902, USA
| | - Brian W Howell
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 505 Irving Ave, Syracuse, NY, 13210, USA
| | - Eric C Olson
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, 505 Irving Ave, Syracuse, NY, 13210, USA. .,Developmental Exposure to Alcohol Research Center (DEARC), Binghamton University, Binghamton, NY, 13902, USA.
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9
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Abstract
UNLABELLED The mechanisms controlling cortical dendrite initiation and targeting are poorly understood. Multiphoton imaging of developing mouse cortex reveals that apical dendrites emerge by direct transformation of the neuron's leading process during the terminal phase of neuronal migration. During this ∼110 min period, the dendritic arbor increases ∼2.5-fold in size and migration arrest occurs below the first stable branch point in the developing arbor. This dendritic outgrowth is triggered at the time of leading process contact with the marginal zone (MZ) and occurs primarily by neurite extension into the extracellular matrix of the MZ. In reeler cortices that lack the secreted glycoprotein Reelin, a subset of neurons completed migration but then retracted and reorganized their arbor in a tangential direction away from the MZ soon after migration arrest. For these reeler neurons, the tangential oriented primary neurites were longer lived than the radially oriented primary neurites, whereas the opposite was true of wild-type (WT) neurons. Application of Reelin protein to reeler cortices destabilized tangential neurites while stabilizing radial neurites and stimulating dendritic growth in the MZ. Therefore, Reelin functions as part of a polarity signaling system that links dendritogenesis in the MZ with cellular positioning and cortical lamination. SIGNIFICANCE STATEMENT Whether the apical dendrite emerges by transformation of the leading process of the migrating neuron or emerges de novo after migration is completed is unclear. Similarly, it is not clear whether the secreted glycoprotein Reelin controls migration and dendritic growth as related or separate processes. Here, multiphoton microscopy reveals the direct transformation of the leading process into the apical dendrite. This transformation is coupled to the successful completion of migration and neuronal soma arrest occurs below the first stable branch point of the nascent dendrite. Deficiency in Reelin causes the forming dendrite to avoid its normal target area and branch aberrantly, leading to improper cellular positioning. Therefore, this study links Reelin-dependent dendritogenesis with migration arrest and cortical lamination.
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10
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Romero AM, Renau-Piqueras J, Marín MP, Esteban-Pretel G. Chronic alcohol exposure affects the cell components involved in membrane traffic in neuronal dendrites. Neurotox Res 2014; 27:43-54. [PMID: 25022897 DOI: 10.1007/s12640-014-9484-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/13/2014] [Accepted: 07/01/2014] [Indexed: 01/09/2023]
Abstract
The specific traffic of the membrane components in neurons is a major requirement to establish and maintain neuronal domains-the axonal and the somatodendritic domains-and their polarized morphology. Unlike axons, dendrites contain membranous organelles, which are involved in the secretory pathway, including the endoplasmic reticulum, the Golgi apparatus and post-Golgi apparatus carriers, the cytoskeleton, and plasma membrane. A variety of molecules and factors are also involved in this process. Previous studies have shown that chronic alcohol exposure negatively affects several of these cell components, such as the Golgi apparatus or cytoskeleton in neurons. Yet very little information is available on the possible effects of this exposure on the remaining cell elements involved in intracellular trafficking in neurons, particularly in dendrites. By qualitative and quantitative electron microscopy, immunofluorescence and immunoblotting, we herein show that chronic exposure to moderate levels (30 mM) of ethanol in cultured neurons reduces the volume and surface density of the rough endoplasmic reticulum, and increases the levels of GRP78, a chaperone involved in endoplasmic reticulum stress. Ethanol also significantly diminishes the proportion of neurons that show an extension of Golgi into dendrites and dendritic Golgi outposts, a structure present exclusively in longer, thicker apical dendrites. Both Golgi apparatus types were also fragmented into a large number of cells. We also investigated the effect of alcohol on the levels of microtubule-based motor proteins KIF5, KIF17, KIFC2, dynein, and myosin IIb, responsible for transporting different cargoes in dendrites. Of these, alcohol differently affects several of them by lowering dynein and raising KIF5, KIFC2, and myosin IIb. These results, together with other previously published ones, suggest that practically all the protein trafficking steps in dendrites are altered to a greater or lesser extent by chronic alcohol exposure in neuronal cells, which may have negative repercussions for the development and maintenance of their polarized morphology and function.
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Affiliation(s)
- Ana M Romero
- Sección de Biología y Patología Celular, Centro de Investigación, Hospital Universitario ''La Fe'', Avenida Campanar 21, 46009, Valencia, Spain
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11
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Olson EC. Analysis of preplate splitting and early cortical development illuminates the biology of neurological disease. Front Pediatr 2014; 2:121. [PMID: 25426475 PMCID: PMC4227491 DOI: 10.3389/fped.2014.00121] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/23/2014] [Indexed: 12/31/2022] Open
Abstract
The development of the layered cerebral cortex starts with a process called preplate splitting. Preplate splitting involves the establishment of prospective cortical layer 6 (L6) neurons within a plexus of pioneer neurons called the preplate. The forming layer 6 splits the preplate into a superficial layer of pioneer neurons called the marginal zone and a deeper layer of pioneer neurons called the subplate. Disruptions of this early developmental event by toxin exposure or mutation are associated with neurological disease including severe intellectual disability. This review explores recent findings that reveal the dynamism of gene expression and morphological differentiation during this early developmental period. Over 1000 genes show expression increases of ≥2-fold during this period in differentiating mouse L6 neurons. Surprisingly, 88% of previously identified non-syndromic intellectual-disability (NS-ID) genes are expressed at this time and show an average expression increase of 1.6-fold in these differentiating L6 neurons. This changing genetic program must, in part, support the dramatic cellular reorganizations that occur during preplate splitting. While different models have been proposed for the formation of a layer of L6 cortical neurons within the preplate, original histological studies and more recent work exploiting transgenic mice suggest that the process is largely driven by the coordinated polarization and coalescence of L6 neurons rather than by cellular translocation or migration. The observation that genes associated with forms of NS-ID are expressed during very early cortical development raises the possibility of studying the relevant biological events at a time point when the cortex is small, contains relatively few cell types, and few functional circuits. This review then outlines how explant models may prove particularly useful in studying the consequence of toxin and mutation on the etiology of some forms of NS-ID.
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Affiliation(s)
- Eric C Olson
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University , Syracuse, NY , USA ; Developmental Exposure Alcohol Research Center (DEARC), Binghamton University , Binghamton, NY , USA
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12
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Nichols AJ, O'Dell RS, Powrozek TA, Olson EC. Ex utero electroporation and whole hemisphere explants: a simple experimental method for studies of early cortical development. J Vis Exp 2013. [PMID: 23609059 DOI: 10.3791/50271] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Cortical development involves complex interactions between neurons and non-neuronal elements including precursor cells, blood vessels, meninges and associated extracellular matrix. Because they provide a suitable organotypic environment, cortical slice explants are often used to investigate those interactions that control neuronal differentiation and development. Although beneficial, the slice explant model can suffer from drawbacks including aberrant cellular lamination and migration. Here we report a whole cerebral hemisphere explant system for studies of early cortical development that is easier to prepare than cortical slices and shows consistent organotypic migration and lamination. In this model system, early lamination and migration patterns proceed normally for a period of two days in vitro, including the period of preplate splitting, during which prospective cortical layer six forms. We then developed an ex utero electroporation (EUEP) approach that achieves -80% success in targeting GFP expression to neurons developing in the dorsal medial cortex. The whole hemisphere explant model makes early cortical development accessible for electroporation, pharmacological intervention and live imaging approaches. This method avoids the survival surgery required of in utero electroporation (IUEP) approaches while improving both transfection and areal targeting consistency. This method will facilitate experimental studies of neuronal proliferation, migration and differentiation.
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Affiliation(s)
- Anna J Nichols
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, USA
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