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Xu Z, Chen Y, Chen Y. Spatiotemporal Regulation of Rho GTPases in Neuronal Migration. Cells 2019; 8:cells8060568. [PMID: 31185627 PMCID: PMC6627650 DOI: 10.3390/cells8060568] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/01/2019] [Accepted: 06/04/2019] [Indexed: 12/17/2022] Open
Abstract
Neuronal migration is essential for the orchestration of brain development and involves several contiguous steps: interkinetic nuclear movement (INM), multipolar–bipolar transition, locomotion, and translocation. Growing evidence suggests that Rho GTPases, including RhoA, Rac, Cdc42, and the atypical Rnd members, play critical roles in neuronal migration by regulating both actin and microtubule cytoskeletal components. This review focuses on the spatiotemporal-specific regulation of Rho GTPases as well as their regulators and effectors in distinct steps during the neuronal migration process. Their roles in bridging extracellular signals and cytoskeletal dynamics to provide optimal structural support to the migrating neurons will also be discussed.
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Affiliation(s)
- Zhenyan Xu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
| | - Yuewen Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
| | - Yu Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
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2
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Gorelik A, Sapir T, Ben-Reuven L, Reiner O. Complement C3 Affects Rac1 Activity in the Developing Brain. Front Mol Neurosci 2018; 11:150. [PMID: 29867343 PMCID: PMC5949353 DOI: 10.3389/fnmol.2018.00150] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/16/2018] [Indexed: 01/09/2023] Open
Abstract
The complement system, which is part of the innate immune response system, has been recently shown to participate in multiple key processes in the developing brain. Here we aimed to elucidate downstream signaling responses linking complement C3, a key molecule of the pathway, to small GTPases, known to affect the cytoskeleton. The expression pattern of the activated small GTPase Rac1 resembled that of complement C3. C3-deficient mice exhibited reduced Rac1 and elevated RhoA activity in comparison with control mice. The most pronounced reduction of Rac1 activity occurred at embryonic day 14. Rac1 has been implicated in neuronal migration as well as neuronal stem cell proliferation and differentiation. Consistent with the reduction in Rac1 activity, the expression of phospho-cofilin, decreased in migrating neurons. Reduced Rac1-GTP was also correlated with a decrease in the expression of progenitor markers (Nestin, Pax6 and Tbr2) and conversely the expression of neuronal markers (Dcx and NeuN) increased in C3 knockout (KO) cortices in comparison with wild-type (WT) cortices. More specifically, C3 deficiency resulted in a reduction in the number of the cells in S-phase and an elevation in the number of cells that precociously exited the cell cycle. Collectively, our findings suggest that C3 impacts the activity of small GTPases resulting in cell cycle defects and premature neuronal differentiation.
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Affiliation(s)
- Anna Gorelik
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Sapir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Lihi Ben-Reuven
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Orly Reiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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3
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Zamboni V, Armentano M, Sarò G, Ciraolo E, Ghigo A, Germena G, Umbach A, Valnegri P, Passafaro M, Carabelli V, Gavello D, Bianchi V, D'Adamo P, de Curtis I, El-Assawi N, Mauro A, Priano L, Ferri N, Hirsch E, Merlo GR. Disruption of ArhGAP15 results in hyperactive Rac1, affects the architecture and function of hippocampal inhibitory neurons and causes cognitive deficits. Sci Rep 2016; 6:34877. [PMID: 27713499 PMCID: PMC5054378 DOI: 10.1038/srep34877] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/19/2016] [Indexed: 11/12/2022] Open
Abstract
During brain development, the small GTPases Rac1/Rac3 play key roles in neuronal migration, neuritogenesis, synaptic formation and plasticity, via control of actin cytoskeleton dynamic. Their activity is positively and negatively regulated by GEFs and GAPs molecules, respectively. However their in vivo roles are poorly known. The ArhGAP15 gene, coding for a Rac-specific GAP protein, is expressed in both excitatory and inhibitory neurons of the adult hippocampus, and its loss results in the hyperactivation of Rac1/Rac3. In the CA3 and dentate gyrus (DG) regions of the ArhGAP15 mutant hippocampus the CR+, PV+ and SST+ inhibitory neurons are reduced in number, due to reduced efficiency and directionality of their migration, while pyramidal neurons are unaffected. Loss of ArhGAP15 alters neuritogenesis and the balance between excitatory and inhibitory synapses, with a net functional result consisting in increased spike frequency and bursts, accompanied by poor synchronization. Thus, the loss of ArhGAP15 mainly impacts on interneuron-dependent inhibition. Adult ArhGAP15−/− mice showed defective hippocampus-dependent functions such as working and associative memories. These findings indicate that a normal architecture and function of hippocampal inhibitory neurons is essential for higher hippocampal functions, and is exquisitely sensitive to ArhGAP15-dependent modulation of Rac1/Rac3.
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Affiliation(s)
- Valentina Zamboni
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Maria Armentano
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Gabriella Sarò
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Elisa Ciraolo
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Alessandra Ghigo
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Giulia Germena
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Alessandro Umbach
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | | | | | | | | | - Veronica Bianchi
- IRCSS San Raffaele Scientific Institute and San Raffaele University, Division of Neuroscience, Milano, Italy
| | - Patrizia D'Adamo
- IRCSS San Raffaele Scientific Institute and San Raffaele University, Division of Neuroscience, Milano, Italy
| | - Ivan de Curtis
- IRCSS San Raffaele Scientific Institute and San Raffaele University, Division of Neuroscience, Milano, Italy
| | - Nadia El-Assawi
- Department of Neurosciences, University of Turin &Div. of Neurology and Neurorehabilitation, S.Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, Piancavallo (VB), Italy
| | - Alessandro Mauro
- Department of Neurosciences, University of Turin &Div. of Neurology and Neurorehabilitation, S.Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, Piancavallo (VB), Italy
| | - Lorenzo Priano
- Department of Neurosciences, University of Turin &Div. of Neurology and Neurorehabilitation, S.Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, Piancavallo (VB), Italy
| | - Nicola Ferri
- Department of Pharmaceutical and Pharmacological Science, University of Padova, Italy
| | - Emilio Hirsch
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
| | - Giorgio R Merlo
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Italy
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4
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Tang BL. Rab, Arf, and Arl-Regulated Membrane Traffic in Cortical Neuron Migration. J Cell Physiol 2015; 231:1417-23. [DOI: 10.1002/jcp.25261] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry; Yong Loo Lin School of Medicine; National University of Singapore; Singapore
- NUS Graduate School for Integrative Sciences and Engineering; National University of Singapore; Singapore
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5
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Tejada-Simon MV. Modulation of actin dynamics by Rac1 to target cognitive function. J Neurochem 2015; 133:767-79. [PMID: 25818528 DOI: 10.1111/jnc.13100] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 03/11/2015] [Accepted: 03/14/2015] [Indexed: 12/14/2022]
Abstract
The small GTPase Rac1 is well known for regulating actin cytoskeleton reorganization in cells. Formation of extensions at the surface of the cell is required for migration and even for cell invasion and metastases. Because an elevated level and hyperactivation of this protein has been associated with metastasis in cancer, direct regulators of Rac1 are currently envisioned as a potential strategy to treat certain cancers. Less research, however, has been done regarding the role of this small GTP-binding protein in brain development, where it has an important role in dendritic spine morphogenesis through the regulation of actin. Alteration of dendritic development and spinogenesis has been often associated with mental disorders. Rac1 is associated with and required for learning and the formation of memories in the brain. Rac1 appears to be dysregulated in certain neurodevelopmental disorders that present all these three alterations: mental retardation, atypical synaptic plasticity and aberrant spine morphology. Thus, to develop novel therapies for rescuing cognitive impairment, a reasonable approach might be to target this protein, Rac1, which plays a pivotal role in directing signals that regulate actin dynamics, which in turn might have an effect in spine cytoarchitecture and synaptic function. It is possible that novel drugs that regulate Rac1 activation and function could modulate actin cytoskeleton and spine dynamics, representing potential candidates to repair intellectual disability in disorders associated with spine abnormalities. Herein, we present a list of the current Rac1 inhibitors that might fulfill this role together with a summary of the latest findings concerning their function as they relate to neuronal studies. While the small GTPase Rac1 is well known for regulating actin cytoskeleton reorganization in different type of cells, it appears to be also required for learning and the formation of memories in the brain. Abnormal regulation of this protein has been associated with cognitive disabilities, atypical synaptic plasticity and abnormal morphology of dendritic spines in certain neurodevelopmental disorders. Thus, modulation of Rac1 activity using novel inhibitors might be a strategy to reestablish cognitive function.
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Affiliation(s)
- Maria V Tejada-Simon
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas, USA.,Department of Biology, University of Houston, Houston, Texas, USA.,Department of Psychology, University of Houston, Houston, Texas, USA.,Biology of Behavior Institute (BoBI), University of Houston, Houston, Texas, USA
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6
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Lian G, Sheen VL. Cytoskeletal proteins in cortical development and disease: actin associated proteins in periventricular heterotopia. Front Cell Neurosci 2015; 9:99. [PMID: 25883548 PMCID: PMC4381626 DOI: 10.3389/fncel.2015.00099] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/07/2015] [Indexed: 01/28/2023] Open
Abstract
The actin cytoskeleton regulates many important cellular processes in the brain, including cell division and proliferation, migration, and cytokinesis and differentiation. These developmental processes can be regulated through actin dependent vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. Many of these processes are mediated by extensive and intimate interactions of actin with cellular membranes and proteins. Disruption in the actin cytoskeleton in the brain gives rise to periventricular heterotopia (PH), a malformation of cortical development, characterized by abnormal neurons clustered deep in the brain along the lateral ventricles. This disorder can give rise to seizures, dyslexia and psychiatric disturbances. Anatomically, PH is characterized by a smaller brain (impaired proliferation), heterotopia (impaired initial migration) and disruption along the neuroependymal lining (impaired cell-cell adhesion). Genes causal for PH have also been implicated in actin-dependent processes. The current review provides mechanistic insight into actin cytoskeletal regulation of cortical development in the context of this malformation of cortical development.
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Affiliation(s)
- Gewei Lian
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School Boston, MA, USA
| | - Volney L Sheen
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School Boston, MA, USA
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7
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Azzarelli R, Guillemot F, Pacary E. Function and regulation of Rnd proteins in cortical projection neuron migration. Front Neurosci 2015; 9:19. [PMID: 25705175 PMCID: PMC4319381 DOI: 10.3389/fnins.2015.00019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/13/2015] [Indexed: 01/08/2023] Open
Abstract
The mammalian cerebral cortex contains a high variety of neuronal subtypes that acquire precise spatial locations and form long or short-range connections to establish functional neuronal circuits. During embryonic development, cortical projection neurons are generated in the areas lining the lateral ventricles and they subsequently undergo radial migration to reach the position of their final maturation within the cortical plate. The control of the neuroblast migratory behavior and the coordination of the migration process with other neurogenic events such as cell cycle exit, differentiation and final maturation are crucial to normal brain development. Among the key regulators of cortical neuron migration, the small GTP binding proteins of the Rho family and the atypical Rnd members play important roles in integrating intracellular signaling pathways into changes in cytoskeletal dynamics and motility behavior. Here we review the role of Rnd proteins during cortical neuronal migration and we discuss both the upstream mechanisms that regulate Rnd protein activity and the downstream molecular pathways that mediate Rnd effects on cell cytoskeleton.
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Affiliation(s)
- Roberta Azzarelli
- Cambridge Department of Oncology, Hutchison/MRC Research Centre, University of Cambridge Cambridge, UK
| | - François Guillemot
- Division of Molecular Neurobiology, MRC National Institute for Medical Research London, UK
| | - Emilie Pacary
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie Bordeaux, France ; Université de Bordeaux Bordeaux, France
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8
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Azzarelli R, Kerloch T, Pacary E. Regulation of cerebral cortex development by Rho GTPases: insights from in vivo studies. Front Cell Neurosci 2015; 8:445. [PMID: 25610373 PMCID: PMC4285737 DOI: 10.3389/fncel.2014.00445] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 12/11/2014] [Indexed: 12/31/2022] Open
Abstract
The cerebral cortex is the site of higher human cognitive and motor functions. Histologically, it is organized into six horizontal layers, each containing unique populations of molecularly and functionally distinct excitatory projection neurons and inhibitory interneurons. The stereotyped cellular distribution of cortical neurons is crucial for the formation of functional neural circuits and it is predominantly established during embryonic development. Cortical neuron development is a multiphasic process characterized by sequential steps of neural progenitor proliferation, cell cycle exit, neuroblast migration and neuronal differentiation. This series of events requires an extensive and dynamic remodeling of the cell cytoskeleton at each step of the process. As major regulators of the cytoskeleton, the family of small Rho GTPases has been shown to play essential functions in cerebral cortex development. Here we review in vivo findings that support the contribution of Rho GTPases to cortical projection neuron development and we address their involvement in the etiology of cerebral cortex malformations.
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Affiliation(s)
- Roberta Azzarelli
- Department of Oncology, Hutchison/MRC Research Centre, Cambridge Biomedical Campus, University of Cambridge Cambridge, UK
| | - Thomas Kerloch
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie Bordeaux, France ; Institut National de la Santé et de la Recherche Médicale, Physiopathologie de la Plasticité Neuronale, Université de Bordeaux Bordeaux, France
| | - Emilie Pacary
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie Bordeaux, France ; Institut National de la Santé et de la Recherche Médicale, Physiopathologie de la Plasticité Neuronale, Université de Bordeaux Bordeaux, France
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9
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Kawauchi T. Regulation of cell adhesion and migration in cortical neurons: Not only Rho but also Rab family small GTPases. Small GTPases 2014; 2:36-40. [PMID: 21686280 DOI: 10.4161/sgtp.2.1.15001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/14/2011] [Accepted: 01/31/2011] [Indexed: 01/25/2023] Open
Abstract
Accumulating evidence indicate that Rho family small GTPases, including RhoA, Rac1 and Cdc42, control cytoskeletal organization and cell adhesion, and thereby cell migration in vitro and in vivo. Recently, the involvement of other small GTPases, such as Rab and Arf family proteins in cell migration has also been evaluated. Rab5, Rab11 and Rab7, which regulate endocytosis, recycling and lysosomal degradation pathways, respectively, are shown to have essential roles in the migration of immature neurons during the development of cerebral cortex in vivo. These Rab proteins control distinct steps of neuronal migration through the regulation of N-cadherin-mediated cell adhesion. In this extra view paper, I will discuss the functions of Rho and Rab family small GTP ases in cell migration with particular focus on the migrating neurons in the developing cerebral cortex.
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Affiliation(s)
- Takeshi Kawauchi
- Department of Anatomy; Keio University School of Medicine; Tokyo, Japan
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10
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Microinjection of membrane-impermeable molecules into single neural stem cells in brain tissue. Nat Protoc 2014; 9:1170-82. [DOI: 10.1038/nprot.2014.074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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11
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Rnd3 coordinates early steps of cortical neurogenesis through actin-dependent and -independent mechanisms. Nat Commun 2013; 4:1635. [PMID: 23535656 PMCID: PMC3920367 DOI: 10.1038/ncomms2614] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 02/19/2013] [Indexed: 02/06/2023] Open
Abstract
The generation of neurons by neural stem cells is a highly choreographed process that requires extensive and dynamic remodelling of the cytoskeleton at each step of the process. The atypical RhoGTPase Rnd3 is expressed by progenitors in the embryonic brain but its role in early steps of neurogenesis has not been addressed. Here we show that silencing Rnd3 in the embryonic cerebral cortex interferes with the interkinetic nuclear migration of radial glial stem cells, disrupts their apical attachment and modifies the orientation of their cleavage plane. These defects are rescued by co-expression of a constitutively active form of cofilin, demonstrating that Rnd3-mediated disassembly of actin filaments coordinates the cellular behaviour of radial glia. Rnd3 also limits the divisions of basal progenitors via a distinct mechanism involving the suppression of cyclin D1 translation. Interestingly, although Rnd3 expression is controlled transcriptionally by Ascl1, this proneural factor is itself required in radial glial progenitors only for proper orientation of cell divisions.
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12
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Evsyukova I, Plestant C, Anton ES. Integrative mechanisms of oriented neuronal migration in the developing brain. Annu Rev Cell Dev Biol 2013; 29:299-353. [PMID: 23937349 DOI: 10.1146/annurev-cellbio-101512-122400] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The emergence of functional neuronal connectivity in the developing cerebral cortex depends on neuronal migration. This process enables appropriate positioning of neurons and the emergence of neuronal identity so that the correct patterns of functional synaptic connectivity between the right types and numbers of neurons can emerge. Delineating the complexities of neuronal migration is critical to our understanding of normal cerebral cortical formation and neurodevelopmental disorders resulting from neuronal migration defects. For the most part, the integrated cell biological basis of the complex behavior of oriented neuronal migration within the developing mammalian cerebral cortex remains an enigma. This review aims to analyze the integrative mechanisms that enable neurons to sense environmental guidance cues and translate them into oriented patterns of migration toward defined areas of the cerebral cortex. We discuss how signals emanating from different domains of neurons get integrated to control distinct aspects of migratory behavior and how different types of cortical neurons coordinate their migratory activities within the developing cerebral cortex to produce functionally critical laminar organization.
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Affiliation(s)
- Irina Evsyukova
- Neuroscience Center and the Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599;
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13
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Ichikawa T, Nakazato K, Keller PJ, Kajiura-Kobayashi H, Stelzer EHK, Mochizuki A, Nonaka S. Live imaging of whole mouse embryos during gastrulation: migration analyses of epiblast and mesodermal cells. PLoS One 2013; 8:e64506. [PMID: 23861733 PMCID: PMC3704669 DOI: 10.1371/journal.pone.0064506] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/15/2013] [Indexed: 11/19/2022] Open
Abstract
During gastrulation in the mouse embryo, dynamic cell movements including epiblast invagination and mesodermal layer expansion lead to the establishment of the three-layered body plan. The precise details of these movements, however, are sometimes elusive, because of the limitations in live imaging. To overcome this problem, we developed techniques to enable observation of living mouse embryos with digital scanned light sheet microscope (DSLM). The achieved deep and high time-resolution images of GFP-expressing nuclei and following 3D tracking analysis revealed the following findings: (i) Interkinetic nuclear migration (INM) occurs in the epiblast at embryonic day (E)6 and 6.5. (ii) INM-like migration occurs in the E5.5 embryo, when the epiblast is a monolayer and not yet pseudostratified. (iii) Primary driving force for INM at E6.5 is not pressure from neighboring nuclei. (iv) Mesodermal cells migrate not as a sheet but as individual cells without coordination.
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Affiliation(s)
- Takehiko Ichikawa
- Laboratory for Spatiotemporal Regulations, National Institute for Basic Biology, Okazaki Aichi, Japan
| | - Kenichi Nakazato
- Theoretical Biology Laboratory, RIKEN Advanced Science Institute, Wako-city, Saitama, Japan
| | - Philipp J. Keller
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Hiroko Kajiura-Kobayashi
- Laboratory for Spatiotemporal Regulations, National Institute for Basic Biology, Okazaki Aichi, Japan
| | - Ernst H. K. Stelzer
- Physical Biology (FB 15 IZN), Buchmann Institute for Molecular Life Sciences (BMLS, CEF-MC), Goethe Universität Frankfurt, Frankfurt am Main, Germany
| | - Atsushi Mochizuki
- Theoretical Biology Laboratory, RIKEN Advanced Science Institute, Wako-city, Saitama, Japan
| | - Shigenori Nonaka
- Laboratory for Spatiotemporal Regulations, National Institute for Basic Biology, Okazaki Aichi, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
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14
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Wu J, Liu L, Matsuda T, Zhao Y, Rebane A, Drobizhev M, Chang YF, Araki S, Arai Y, March K, Hughes TE, Sagou K, Miyata T, Nagai T, Li WH, Campbell RE. Improved orange and red Ca²± indicators and photophysical considerations for optogenetic applications. ACS Chem Neurosci 2013; 4:963-72. [PMID: 23452507 PMCID: PMC3689190 DOI: 10.1021/cn400012b] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 03/01/2013] [Indexed: 11/30/2022] Open
Abstract
We have used protein engineering to expand the palette of genetically encoded calcium ion (Ca(2+)) indicators to include orange and improved red fluorescent variants, and validated the latter for combined use with optogenetic activation by channelrhodopsin-2 (ChR2). These indicators feature intensiometric signal changes that are 1.7- to 9.7-fold improved relatively to the progenitor Ca(2+) indicator, R-GECO1. In the course of this work, we discovered a photoactivation phenomenon in red fluorescent Ca(2+) indicators that, if not appreciated and accounted for, can cause false-positive artifacts in Ca(2+) imaging traces during optogenetic activation with ChR2. We demonstrate, in both a beta cell line and slice culture of developing mouse neocortex, that these artifacts can be avoided by using an appropriately low intensity of blue light for ChR2 activation.
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Affiliation(s)
- Jiahui Wu
- Department of Chemistry, University
of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Lin Liu
- Departments of Cell Biology and of
Biochemistry, University of Texas Southwestern Medical
Center, 6000 Harry Hines Blvd, Dallas, Texas 75390-9039,
United States
| | - Tomoki Matsuda
- The Institute
of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047 Japan
| | - Yongxin Zhao
- Department of Chemistry, University
of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Aleksander Rebane
- Department of Physics, Montana
State University, Bozeman, Montana 59717, United States
| | - Mikhail Drobizhev
- Department of Physics, Montana
State University, Bozeman, Montana 59717, United States
| | - Yu-Fen Chang
- The Institute
of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047 Japan
| | - Satoko Araki
- The Institute
of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047 Japan
| | - Yoshiyuki Arai
- The Institute
of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047 Japan
| | - Kelsey March
- Department of Cell Biology and
Neuroscience, Montana State University,
Bozeman, Montana, United States
| | - Thomas E. Hughes
- Department of Cell Biology and
Neuroscience, Montana State University,
Bozeman, Montana, United States
| | - Ken Sagou
- Graduate School of Medicine, Nagoya University, 65 Tsurumai-Cho, Showa-Ku, Nagoya, Aichi, 466-8550, Japan
| | - Takaki Miyata
- Graduate School of Medicine, Nagoya University, 65 Tsurumai-Cho, Showa-Ku, Nagoya, Aichi, 466-8550, Japan
| | - Takeharu Nagai
- The Institute
of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047 Japan
| | - Wen-hong Li
- Departments of Cell Biology and of
Biochemistry, University of Texas Southwestern Medical
Center, 6000 Harry Hines Blvd, Dallas, Texas 75390-9039,
United States
| | - Robert E. Campbell
- Department of Chemistry, University
of Alberta, Edmonton, Alberta T6G 2G2, Canada
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15
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Shinohara H, Sakayori N, Takahashi M, Osumi N. Ninein is essential for the maintenance of the cortical progenitor character by anchoring the centrosome to microtubules. Biol Open 2013; 2:739-49. [PMID: 23862022 PMCID: PMC3711042 DOI: 10.1242/bio.20135231] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 04/24/2013] [Indexed: 11/20/2022] Open
Abstract
The mammalian cerebral cortex develops from proliferative apical progenitor cells (APs) that exhibit cell cycle-dependent nuclear movement (interkinetic nuclear migration; INM), which may be important for efficient and continuous production of neurons. The Pax6 transcription factor plays a major role in INM by regulating various downstream molecules. We have previously observed abnormal INM and unstable localization of the centrosome in APs of the Pax6 homozygous mutant rat embryo. To understand the mechanisms of INM, we focused on the centrosomes of APs. One of the centrosomal proteins, ninein, is specifically localized in the centrosome of APs. We observed a dramatic downregulation of ninein in APs of the Pax6 mutant. Moreover, knockdown of ninein by RNAi induced ectopic distribution of reduced numbers of BrdU-positive (S-phase) and PH3-positive (M-phase) cells. Furthermore, time-lapsed imaging demonstrated that knockdown of ninein in vivo induced abnormal INM. Finally, we observed impaired microtubule regrowth in neural progenitors taken from Pax6 homozygous mutant rat embryos, which was recovered by via ninein overexpression. We also found that ninein knockdown enlarged the surface size area of apical endfeet of the APs. Our results suggest that ninein plays a role in the molecular machinery essential for INM by connecting microtubules to the centrosome.
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Affiliation(s)
- Hiroshi Shinohara
- Present address: Department of Histology and Neuroanatomy, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan
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Kawauchi T, Shikanai M, Kosodo Y. Extra-cell cycle regulatory functions of cyclin-dependent kinases (CDK) and CDK inhibitor proteins contribute to brain development and neurological disorders. Genes Cells 2013; 18:176-94. [PMID: 23294285 PMCID: PMC3594971 DOI: 10.1111/gtc.12029] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 11/26/2012] [Indexed: 12/21/2022]
Abstract
In developing brains, neural progenitors exhibit cell cycle-dependent nuclear movement within the ventricular zone [interkinetic nuclear migration (INM)] and actively proliferate to produce daughter progenitors and/or neurons, whereas newly generated neurons exit from the cell cycle and begin pial surface-directed migration and maturation. Dysregulation of the balance between the proliferation and the cell cycle exit in neural progenitors is one of the major causes of microcephaly (small brain). Recent studies indicate that cell cycle machinery influences not only the proliferation but also INM in neural progenitors. Furthermore, several cell cycle-related proteins, including p27(kip1) , p57(kip2) , Cdk5, and Rb, regulate the migration of neurons in the postmitotic state, suggesting that the growth arrest confers dual functions on cell cycle regulators. Consistently, several types of microcephaly occur in conjunction with neuronal migration disorders, such as periventricular heterotopia and lissencephaly. However, cell cycle re-entry by disturbance of growth arrest in mature neurons is thought to trigger neuronal cell death in Alzheimer's disease. In this review, we introduce the cell cycle protein-mediated regulation of two types of nuclear movement, INM and neuronal migration, during cerebral cortical development, and discuss the roles of growth arrest in cortical development and neurological disorders.
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Affiliation(s)
- Takeshi Kawauchi
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama, 332-0012, Japan.
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Tiam1 regulates the Wnt/Dvl/Rac1 signaling pathway and the differentiation of midbrain dopaminergic neurons. Mol Cell Biol 2012; 33:59-70. [PMID: 23109420 DOI: 10.1128/mcb.00745-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Understanding the mechanisms that drive the differentiation of dopaminergic (DA) neurons is crucial for successful development of novel therapies for Parkinson's disease, in which DA neurons progressively degenerate. However, the mechanisms underlying the differentiation-promoting effects of Wnt5a on DA precursors are poorly understood. Here, we present the molecular and functional characterization of a signaling pathway downstream of Wnt5a, the Wnt/Dvl/Rac1 pathway. First, we characterize the interaction between Rac1 and Dvl and identify the N-terminal part of Dvl3 as necessary for Rac1 binding. Next, we show that Tiam1, a Rac1 guanosine exchange factor (GEF), is expressed in the ventral midbrain, interacts with Dvl, facilitates Dvl-Rac1 interaction, and is required for Dvl- or Wnt5a-induced activation of Rac1. Moreover, we show that Wnt5a promotes whereas casein kinase 1 (CK1), a negative regulator of the Wnt/Dvl/Rac1 pathway, abolishes the interactions between Dvl and Tiam1. Finally, using ventral midbrain neurosphere cultures, we demonstrate that the generation of DA neurons in culture is impaired after Tiam1 knockdown, indicating that Tiam1 is required for midbrain DA differentiation. In summary, our data identify Tiam1 as a novel regulator of DA neuron development and as a Dvl-associated and Rac1-specific GEF acting in the Wnt/Dvl/Rac1 pathway.
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Spear PC, Erickson CA. Apical movement during interkinetic nuclear migration is a two-step process. Dev Biol 2012; 370:33-41. [PMID: 22884563 DOI: 10.1016/j.ydbio.2012.06.031] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 06/20/2012] [Accepted: 06/20/2012] [Indexed: 01/13/2023]
Abstract
Neural progenitor cells in the pseudostratified neuroepithelium in vertebrates undergo interkinetic nuclear migration, which results in mitotic cells localized to the apical surface. Interphase nuclei are distributed throughout the rest of the epithelium. How mitosis is coordinated with nuclear movement is unknown, and the mechanism by which the nucleus migrates apically is controversial. Using time-lapse confocal microscopy, we show that nuclei migrate apically in G2 phase via microtubules. However, late in G2, centrosomes leave the apical surface after cilia are disassembled, and mitosis initiates away from the apical surface. The mitotic cell then rounds up to the apical surface, which is an actin-dependent process. This behavior is observed in both chicken neural-tube-slice preparations and in mouse cortical slices, and therefore is likely to be a general feature of interkinetic nuclear migration. We propose a new model for interkinetic nuclear migration in which actin and microtubules are used to position the mitotic cell at the apical surface.
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Affiliation(s)
- Philip C Spear
- Department of Molecular and Cellular Biology, One Shields Ave., UC Davis, Davis, CA 95616, United States.
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19
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Kosodo Y. Interkinetic nuclear migration: beyond a hallmark of neurogenesis. Cell Mol Life Sci 2012; 69:2727-38. [PMID: 22415322 PMCID: PMC11115108 DOI: 10.1007/s00018-012-0952-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 02/18/2012] [Accepted: 02/23/2012] [Indexed: 12/23/2022]
Abstract
Interkinetic nuclear migration (INM) is an oscillatory nuclear movement that is synchronized with the progression of the cell cycle. The efforts of several researchers, following the first report of INM in 1935, have revealed many of the molecular mechanisms of this fascinating phenomenon linking the timing of the cell cycle and nuclear positioning in tissue. Researchers are now faced with a more fundamental question: is INM important for tissue, particularly brain, development? In this review, I summarize the current understanding of the regulatory mechanisms governing INM, investigations involving several different tissues and species, and possible explanations for how nuclear movement affects cell-fate determination and tissue formation.
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Affiliation(s)
- Yoichi Kosodo
- Department of Anatomy, Kawasaki Medical School, 577 Matsushima, Kurashiki 701-0192, Japan.
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20
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DOCK7 interacts with TACC3 to regulate interkinetic nuclear migration and cortical neurogenesis. Nat Neurosci 2012; 15:1201-10. [PMID: 22842144 PMCID: PMC3431462 DOI: 10.1038/nn.3171] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 06/26/2012] [Indexed: 12/12/2022]
Abstract
Neurogenesis in the developing neocortex relies on the ability of radial glial progenitor cells (RGCs) to switch from proliferative to differentiative neuron-generating divisions, but the molecular mechanisms that control this switch in a correct temporal manner are not well understood. Here, we show that DOCK7, a member of the DOCK180 family of proteins, plays an important role in the regulation of RGC proliferation versus differentiation. Silencing of DOCK7 in RGCs of developing mouse embryos impedes neuronal differentiation and maintains cells as cycling progenitors. In contrast, DOCK7 overexpression promotes RGC differentiation to basal progenitors and neurons. We further present evidence that DOCK7 influences neurogenesis by controlling apically directed interkinetic nuclear migration (INM) of RGCs. Importantly, DOCK7 exerts its effects by antagonizing the microtubule growth-promoting function of the centrosome-associated protein TACC3. Thus, DOCK7 interaction with TACC3 controls INM and the genesis of neurons from RGCs during cortical development.
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Luxton GWG, Gomes ER, Folker ES, Worman HJ, Gundersen GG. TAN lines: a novel nuclear envelope structure involved in nuclear positioning. Nucleus 2012; 2:173-81. [PMID: 21818410 DOI: 10.4161/nucl.2.3.16243] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 04/30/2011] [Accepted: 05/02/2011] [Indexed: 11/19/2022] Open
Abstract
Nuclear position is actively controlled and can be adjusted according to the needs of a cell by nuclear movement. Microtubules mediate the majority of nuclear movements studied to date, although examples of nuclear movements mediated by the actin cytoskeleton have been described. One such actin-dependent nuclear movement occurs during centrosome orientation in fibroblasts polarizing for migration. Here, the centrosome is maintained at the cell center while the nucleus is moved to the cell rear by actin retrograde flow thus positioning the centrosome between the nucleus and the leading edge of the cell. We have explored the molecular mechanism for actin dependent movement of the nucleus during centrosome centration. We found that a novel linear array of nuclear envelope membrane proteins composed of nesprin-2G and SUN2, called transmembrane actin-associated nuclear (TAN) lines, couple the nucleus to moving actin cables resulting in the nucleus being positioned toward the cell rear. TAN lines are anchored by A-type lamins and this allows the forces generated by the actin cytoskeleton to be transmitted across the nuclear envelope to move the nucleus. Here we review the data supporting this mechanism for nuclear movement, discuss questions remaining to be addressed and consider how this new mechanism of nuclear movement may shed light on human disease.
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Affiliation(s)
- G W Gant Luxton
- Department of Pathology and Cell Biology, Columbia University, New York, USA
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22
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LaMonica BE, Lui JH, Wang X, Kriegstein AR. OSVZ progenitors in the human cortex: an updated perspective on neurodevelopmental disease. Curr Opin Neurobiol 2012; 22:747-53. [PMID: 22487088 DOI: 10.1016/j.conb.2012.03.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 03/09/2012] [Indexed: 11/27/2022]
Abstract
Recent discoveries concerning the architecture and cellular dynamics of the developing human brain are revealing new differences between mouse and human cortical development. In mice, neurons are produced by ventricular radial glial (RG) cells and subventricular zone intermediate progenitor (IP) cells. In the human cortex, both ventricular RG and highly motile outer RG cells generate IP cells, which undergo multiple rounds of transit amplification in the outer subventricular zone before producing neurons. This creates a more complex environment for neurogenesis and neuronal migration, adding new arenas in which neurodevelopmental disease gene mutation could disrupt corticogenesis. A more complete understanding of disease mechanisms will involve use of emerging model systems with developmental programs more similar to that of the human neocortex.
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Affiliation(s)
- Bridget E LaMonica
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF, University of California San Francisco, San Francisco, CA 94143, USA
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Vidaki M, Tivodar S, Doulgeraki K, Tybulewicz V, Kessaris N, Pachnis V, Karagogeos D. Rac1-dependent cell cycle exit of MGE precursors and GABAergic interneuron migration to the cortex. Cereb Cortex 2012; 22:680-92. [PMID: 21690261 PMCID: PMC3589917 DOI: 10.1093/cercor/bhr145] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Cortical γ-aminobutyric acid (GABA)ergic interneurons are characterized by extraordinary neurochemical and functional diversity. Although recent studies have uncovered some of the molecular components underlying interneuron development, including the cellular and molecular mechanisms guiding their migration to the cortex, the intracellular components involved are still unknown. Rac1, a member of the Rac subfamily of Rho-GTPases, has been implicated in various cellular processes such as cell cycle dynamics, axonogenesis, and migration. In this study, we have addressed the specific role of Rac1 in interneuron progenitors originating in the medial ganglionic eminence, via Cre/loxP technology. We show that ablation of Rac1 from Nkx2.1-positive progenitors, results in a migratory impairment. As a consequence, only half of GABAergic interneurons are found in the postnatal cortex. The rest remain aggregated in the ventral telencephalon and show morphological defects in their growing processes in vitro. Ablation of Rac1 from postmitotic progenitors does not result in similar defects, thus underlying a novel cell autonomous and stage-specific requirement for Rac1 activity, within proliferating progenitors of cortical interneurons. Rac1 is necessary for their transition from G1 to S phase, at least in part by regulating cyclin D levels and retinoblastoma protein phosphorylation.
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Affiliation(s)
- Marina Vidaki
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Simona Tivodar
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Katerina Doulgeraki
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Victor Tybulewicz
- Division of Immune Cell Biology, Medical Research Council, National Institute for Medical Research, NW7-1AA London, UK
| | - Nicoletta Kessaris
- Wolfson Institute for Biomedical Research
- Department of Cell & Developmental Biology, University College London, WC1E-6BT London, UK
| | - Vassilis Pachnis
- Division of Molecular Neurobiology, Medical Research Council, National Institute for Medical Research, NW7-1AA London, UK
| | - Domna Karagogeos
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
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Govek EE, Hatten ME, Van Aelst L. The role of Rho GTPase proteins in CNS neuronal migration. Dev Neurobiol 2011; 71:528-53. [PMID: 21557504 DOI: 10.1002/dneu.20850] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The architectonics of the mammalian brain arise from a remarkable range of directed cell migrations, which orchestrate the emergence of cortical neuronal layers and pattern brain circuitry. At different stages of cortical histogenesis, specific modes of cell motility are essential to the stepwise formation of cortical architecture. These movements range from interkinetic nuclear movements in the ventricular zone, to migrations of early-born, postmitotic polymorphic cells into the preplate, to the radial migration of precursors of cortical output neurons across the thickening cortical wall, and the vast, tangential migrations of interneurons from the basal forebrain into the emerging cortical layers. In all cases, actomyosin motors act in concert with cell adhesion receptor systems to provide the force and traction needed for forward movement. As key regulators of actin and microtubule cytoskeletons, cell polarity, and adhesion, the Rho GTPases play critical roles in CNS neuronal migration. This review will focus on the different types of migration in the developing neocortex and cerebellar cortex, and the role of the Rho GTPases, their regulators and effectors in these CNS migrations, with particular emphasis on their involvement in radial migration.
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Affiliation(s)
- Eve-Ellen Govek
- Laboratory of Developmental Neurobiology, The Rockefeller University, NY 10065, USA
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25
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Kosodo Y, Suetsugu T, Suda M, Mimori-Kiyosue Y, Toida K, Baba SA, Kimura A, Matsuzaki F. Regulation of interkinetic nuclear migration by cell cycle-coupled active and passive mechanisms in the developing brain. EMBO J 2011; 30:1690-704. [PMID: 21441895 PMCID: PMC3101991 DOI: 10.1038/emboj.2011.81] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 02/23/2011] [Indexed: 11/09/2022] Open
Abstract
A hallmark of neurogenesis in the vertebrate brain is the apical-basal nuclear oscillation in polarized neural progenitor cells. Known as interkinetic nuclear migration (INM), these movements are synchronized with the cell cycle such that nuclei move basally during G1-phase and apically during G2-phase. However, it is unknown how the direction of movement and the cell cycle are tightly coupled. Here, we show that INM proceeds through the cell cycle-dependent linkage of cell-autonomous and non-autonomous mechanisms. During S to G2 progression, the microtubule-associated protein Tpx2 redistributes from the nucleus to the apical process, and promotes nuclear migration during G2-phase by altering microtubule organization. Thus, Tpx2 links cell-cycle progression and autonomous apical nuclear migration. In contrast, in vivo observations of implanted microbeads, acute S-phase arrest of surrounding cells and computational modelling suggest that the basal migration of G1-phase nuclei depends on a displacement effect by G2-phase nuclei migrating apically. Our model for INM explains how the dynamics of neural progenitors harmonize their extensive proliferation with the epithelial architecture in the developing brain.
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Affiliation(s)
- Yoichi Kosodo
- Laboratory for Cell Asymmetry, RIKEN Center for Developmental Biology, Kobe, Japan.
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26
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Abstract
Interkinetic nuclear migration (INM), the movement of neuroepithelial and radial glial cell nuclei along the apical-basal axis in concert with the cell cycle, underlies the pseudostratification of the ventricular zone (VZ). Recent studies provide insight into the molecular mechanisms of INM and its effects on neural progenitor cell fate determination. Moreover, INM not only has a key role in increasing the VZ progenitor pool, but also may have set the stage for the evolution of subventricular zone progenitors implicated in cortical expansion.
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Larson DE, Johnson RI, Swat M, Cordero JB, Glazier JA, Cagan RL. Computer simulation of cellular patterning within the Drosophila pupal eye. PLoS Comput Biol 2010; 6:e1000841. [PMID: 20617161 PMCID: PMC2895643 DOI: 10.1371/journal.pcbi.1000841] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 05/28/2010] [Indexed: 01/28/2023] Open
Abstract
We present a computer simulation and associated experimental validation of assembly of glial-like support cells into the interweaving hexagonal lattice that spans the Drosophila pupal eye. This process of cell movements organizes the ommatidial array into a functional pattern. Unlike earlier simulations that focused on the arrangements of cells within individual ommatidia, here we examine the local movements that lead to large-scale organization of the emerging eye field. Simulations based on our experimental observations of cell adhesion, cell death, and cell movement successfully patterned a tracing of an emerging wild-type pupal eye. Surprisingly, altering cell adhesion had only a mild effect on patterning, contradicting our previous hypothesis that the patterning was primarily the result of preferential adhesion between IRM-class surface proteins. Instead, our simulations highlighted the importance of programmed cell death (PCD) as well as a previously unappreciated variable: the expansion of cells' apical surface areas, which promoted rearrangement of neighboring cells. We tested this prediction experimentally by preventing expansion in the apical area of individual cells: patterning was disrupted in a manner predicted by our simulations. Our work demonstrates the value of combining computer simulation with in vivo experiments to uncover novel mechanisms that are perpetuated throughout the eye field. It also demonstrates the utility of the Glazier-Graner-Hogeweg model (GGH) for modeling the links between local cellular interactions and emergent properties of developing epithelia as well as predicting unanticipated results in vivo.
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Affiliation(s)
- David E. Larson
- The Genome Center at Washington University, St. Louis, Missouri, United States of America
| | - Ruth I. Johnson
- Department of Developmental and Regenerative Biology, Mount Sinai Medical School, New York, New York, United States of America
| | - Maciej Swat
- Biocomplexity Institute and Department of Physics, Indiana University, Bloomington, Indiana, United States of America
| | - Julia B. Cordero
- The Beatson Institute for Cancer Research, Colorectal Cancer and Wnt Signaling Group, Glasgow, United Kingdom
| | - James A. Glazier
- Biocomplexity Institute and Department of Physics, Indiana University, Bloomington, Indiana, United States of America
| | - Ross L. Cagan
- Department of Developmental and Regenerative Biology, Mount Sinai Medical School, New York, New York, United States of America
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Cremasco V, Benasciutti E, Cella M, Kisseleva M, Croke M, Faccio R. Phospholipase C gamma 2 is critical for development of a murine model of inflammatory arthritis by affecting actin dynamics in dendritic cells. PLoS One 2010; 5:e8909. [PMID: 20111715 PMCID: PMC2811739 DOI: 10.1371/journal.pone.0008909] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 10/13/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Dendritic cells (DCs) are highly specialized cells, which capture antigen in peripheral tissues and migrate to lymph nodes, where they dynamically interact with and activate T cells. Both migration and formation of DC-T cell contacts depend on cytoskeleton plasticity. However, the molecular bases governing these events have not been completely defined. METHODOLOGY/PRINCIPAL FINDINGS Utilizing a T cell-dependent model of arthritis, we find that PLCgamma2-/- mice are protected from local inflammation and bone erosion. PLCgamma2 controls actin remodeling in dendritic cells, thereby affecting their capacity to prime T cells. DCs from PLCgamma2-/- mice mature normally, however they lack podosomes, typical actin structures of motile cells. Absence of PLCgamma2 impacts both DC trafficking to the lymph nodes and migration towards CCL21. The interaction with T cells is also affected by PLCgamma2 deficiency. Mechanistically, PLCgamma2 is activated by CCL21 and modulates Rac activation. Rac1/2-/- DCs also lack podosomes and do not respond to CCL21. Finally, antigen pulsed PLCgamma2-/- DCs fail to promote T cell activation and induce inflammation in vivo when injected into WT mice. Conversely, injection of WT DCs into PLCgamma2-/- mice rescues the inflammatory response but not focal osteolysis, confirming the importance of PLCgamma2 both in immune and bone systems. CONCLUSIONS/SIGNIFICANCE This study demonstrates a critical role for PLCgamma2 in eliciting inflammatory responses by regulating actin dynamics in DCs and positions the PLCgamma2 pathway as a common orchestrator of bone and immune cell functions during arthritis.
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Affiliation(s)
- Viviana Cremasco
- Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Elisa Benasciutti
- Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Molecular Genetics, S. Raffaele Scientific Institute, Milano, Italy
| | - Marina Cella
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Marina Kisseleva
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Monica Croke
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Roberta Faccio
- Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Human Anatomy and Histology, University of Bari, Bari, Italy
- * E-mail:
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Myosin II is required for interkinetic nuclear migration of neural progenitors. Proc Natl Acad Sci U S A 2009; 106:16487-92. [PMID: 19805325 DOI: 10.1073/pnas.0908928106] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Interkinetic nuclear migration (INM) is a hallmark of the polarized stem and progenitor cells in the ventricular zone (VZ) of the developing vertebrate CNS. INM is responsible for the pseudostratification of the VZ, a crucial aspect of brain evolution. The nuclear migration toward the apical centrosomes in G2 is thought to be a dynein-microtubule-based process. By contrast, the cytoskeletal machinery involved in the basally directed nuclear translocation away from the centrosome in G1 has been enigmatic. Studying the latter aspect of INM requires manipulation of the cytoskeleton without impairing mitosis and cytokinesis. To this end, we have established a culture system of mouse embryonic telencephalon that reproduces cortical development, and have applied it to explore a role of actomyosin in INM. Using the nonmuscle myosin II inhibitor blebbistatin at a low concentration at which neither cell cycle progression nor cytokinesis is impaired, we show that myosin II is required for the apical-to-basal (ap-->bl), ab-centrosomal INM. Myosin II activity is also necessary for the nuclear translocation during delamination of subventricular zone (SVZ) cells, a second, telencephalon-specific type of neural progenitor. Moreover, the inhibition of ab-centrosomal INM changes the balance between VZ and SVZ progenitor cell fate. Our data suggest a unifying concept in which the actomyosin contraction underlying ab-centrosomal INM sets the stage for the evolutionary increase in VZ pseudostratification and for SVZ progenitor delamination, a key process in cortical expansion.
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