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Khalili B, Lovelace HD, Rutkowski DM, Holz D, Vavylonis D. Fission Yeast Polarization: Modeling Cdc42 Oscillations, Symmetry Breaking, and Zones of Activation and Inhibition. Cells 2020; 9:E1769. [PMID: 32722101 PMCID: PMC7464287 DOI: 10.3390/cells9081769] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/22/2020] [Accepted: 07/23/2020] [Indexed: 12/24/2022] Open
Abstract
Cells polarize for growth, motion, or mating through regulation of membrane-bound small GTPases between active GTP-bound and inactive GDP-bound forms. Activators (GEFs, GTP exchange factors) and inhibitors (GAPs, GTPase activating proteins) provide positive and negative feedbacks. We show that a reaction-diffusion model on a curved surface accounts for key features of polarization of model organism fission yeast. The model implements Cdc42 membrane diffusion using measured values for diffusion coefficients and dissociation rates and assumes a limiting GEF pool (proteins Gef1 and Scd1), as in prior models for budding yeast. The model includes two types of GAPs, one representing tip-localized GAPs, such as Rga3; and one representing side-localized GAPs, such as Rga4 and Rga6, that we assume switch between fast and slow diffusing states. After adjustment of unknown rate constants, the model reproduces active Cdc42 zones at cell tips and the pattern of GEF and GAP localization at cell tips and sides. The model reproduces observed tip-to-tip oscillations with periods of the order of several minutes, as well as asymmetric to symmetric oscillations transitions (corresponding to NETO "new end take off"), assuming the limiting GEF amount increases with cell size.
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Affiliation(s)
- Bita Khalili
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (B.K.); (H.D.L.); (D.M.R.); (D.H.)
| | - Hailey D. Lovelace
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (B.K.); (H.D.L.); (D.M.R.); (D.H.)
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29631, USA
| | - David M. Rutkowski
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (B.K.); (H.D.L.); (D.M.R.); (D.H.)
| | - Danielle Holz
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (B.K.); (H.D.L.); (D.M.R.); (D.H.)
| | - Dimitrios Vavylonis
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (B.K.); (H.D.L.); (D.M.R.); (D.H.)
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Sierksma MC, Tedja MS, Borst JGG. In vivo matching of postsynaptic excitability with spontaneous synaptic inputs during formation of the rat calyx of Held synapse. J Physiol 2016; 595:207-231. [PMID: 27426483 DOI: 10.1113/jp272780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/07/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neurons in the medial nucleus of the trapezoid body of anaesthetized rats of postnatal day (P)2-6 showed burst firing with a preferred interval of about 100 ms, which was stable, and a second preferred interval of 5-30 ms, which shortened during development. In 3 out of 132 cases, evidence for the presence of two large inputs was found. In vivo whole-cell recordings revealed that the excitability of the principal neuron and the size of its largest synaptic inputs were developmentally matched. At P2-4, action potentials were triggered by barrages of small synaptic events that summated to plateau potentials, while at later stages firing depended on a single, large and often prespike-associated input, which is probably the nascent calyx of Held. Simulations with a Hodgkin-Huxley-like model, which was based on fits of the intrinsic postsynaptic properties, suggested an essential role for the low-threshold potassium conductance in this transition. ABSTRACT In the adult, principal neurons of the medial nucleus of the trapezoid body (MNTB) are typically contacted by a single, giant terminal called the calyx of Held, whereas during early development a principal neuron receives inputs from many axons. How these changes in innervation impact the postsynaptic activity has not yet been studied in vivo. We therefore recorded spontaneous inputs and intrinsic properties of principal neurons in anaesthetized rat pups during the developmental period in which the calyx forms. A characteristic bursting pattern could already be observed at postnatal day (P)2, before formation of the calyx. At this age, action potentials (APs) were triggered by barrages of summating EPSPs causing plateau depolarizations. In contrast, at P5, a single EPSP reliably triggered APs, resulting in a close match between pre- and postsynaptic firing. Postsynaptic excitability and the size of the largest synaptic events were developmentally matched. The developmental changes in intrinsic properties were estimated by fitting in vivo current injections to a Hodgkin-Huxley-type model of the principal neuron. Our simulations indicated that the developmental increases in Ih , low-threshold K+ channels and leak currents contributed to the reduction in postsynaptic excitability, but that low-threshold K+ channels specifically functioned as a dampening influence in the near-threshold range, thus precluding small inputs from triggering APs. Together, these coincident changes help to propagate bursting activity along the auditory brainstem, and are essential steps towards establishing the relay function of the calyx of Held synapse.
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Affiliation(s)
- Martijn C Sierksma
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Milly S Tedja
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Taverna E, Mora-Bermúdez F, Strzyz PJ, Florio M, Icha J, Haffner C, Norden C, Wilsch-Bräuninger M, Huttner WB. Non-canonical features of the Golgi apparatus in bipolar epithelial neural stem cells. Sci Rep 2016; 6:21206. [PMID: 26879757 PMCID: PMC4754753 DOI: 10.1038/srep21206] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/19/2016] [Indexed: 12/13/2022] Open
Abstract
Apical radial glia (aRG), the stem cells in developing neocortex, are unique bipolar epithelial cells, extending an apical process to the ventricle and a basal process to the basal lamina. Here, we report novel features of the Golgi apparatus, a central organelle for cell polarity, in mouse aRGs. The Golgi was confined to the apical process but not associated with apical centrosome(s). In contrast, in aRG-derived, delaminating basal progenitors that lose apical polarity, the Golgi became pericentrosomal. The aRG Golgi underwent evolutionarily conserved, accordion-like compression and extension concomitant with cell cycle-dependent nuclear migration. Importantly, in line with endoplasmic reticulum but not Golgi being present in the aRG basal process, its plasma membrane contained glycans lacking Golgi processing, consistent with direct ER-to-cell surface membrane traffic. Our study reveals hitherto unknown complexity of neural stem cell polarity, differential Golgi contribution to their specific architecture, and fundamental Golgi re-organization upon cell fate change.
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Affiliation(s)
- Elena Taverna
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Felipe Mora-Bermúdez
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Paulina J Strzyz
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Marta Florio
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Jaroslav Icha
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Christiane Haffner
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Caren Norden
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | | | - Wieland B Huttner
- Max-Planck Inst. of Mol. Cell Biol. and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
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Abstract
Primary cilia are unique sensory organelles that coordinate cellular signaling networks in vertebrates. Inevitably, defects in the formation or function of primary cilia lead to imbalanced regulation of cellular processes that causes multisystemic disorders and diseases, commonly known as ciliopathies. Mounting evidence has demonstrated that primary cilia coordinate multiple activities that are required for cell migration, which, when they are aberrantly regulated, lead to defects in organogenesis and tissue repair, as well as metastasis of tumors. Here, we present an overview on how primary cilia may contribute to the regulation of the cellular signaling pathways that control cyclic processes in directional cell migration.
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Affiliation(s)
- Iben Rønn Veland
- Iben Rønn Veland ( ) is a postdoctoral researcher from the Christensen Lab, at the University of Copenhagen, Denmark, and she studies the role of primary cilia in cell polarization and migration. Louise Lindbæk ( ) is a PhD student in the Christensen Lab, and she studies the function of primary cilia in neurogenesis and brain development. Søren Tvorup Christensen ( ) is a professor at the University of Copenhagen. He studies how primary cilia coordinate signaling pathways during development and in tissue homeostasis
| | - Louise Lindbæk
- Iben Rønn Veland ( ) is a postdoctoral researcher from the Christensen Lab, at the University of Copenhagen, Denmark, and she studies the role of primary cilia in cell polarization and migration. Louise Lindbæk ( ) is a PhD student in the Christensen Lab, and she studies the function of primary cilia in neurogenesis and brain development. Søren Tvorup Christensen ( ) is a professor at the University of Copenhagen. He studies how primary cilia coordinate signaling pathways during development and in tissue homeostasis
| | - Søren Tvorup Christensen
- Iben Rønn Veland ( ) is a postdoctoral researcher from the Christensen Lab, at the University of Copenhagen, Denmark, and she studies the role of primary cilia in cell polarization and migration. Louise Lindbæk ( ) is a PhD student in the Christensen Lab, and she studies the function of primary cilia in neurogenesis and brain development. Søren Tvorup Christensen ( ) is a professor at the University of Copenhagen. He studies how primary cilia coordinate signaling pathways during development and in tissue homeostasis
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Ackley BD. Wnt-signaling and planar cell polarity genes regulate axon guidance along the anteroposterior axis in C. elegans. Dev Neurobiol 2014; 74:781-96. [PMID: 24214205 PMCID: PMC4167394 DOI: 10.1002/dneu.22146] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/18/2013] [Accepted: 11/02/2013] [Indexed: 11/10/2022]
Abstract
During the development of the nervous system, neurons encounter signals that inform their outgrowth and polarization. Understanding how these signals combinatorially function to pattern the nervous system is of considerable interest to developmental neurobiologists. The Wnt ligands and their receptors have been well characterized in polarizing cells during asymmetric cell division. The planar cell polarity (PCP) pathway is also critical for cell polarization in the plane of an epithelium. The core set of PCP genes include members of the conserved Wnt-signaling pathway, such as Frizzled and Disheveled, but also the cadherin-domain protein Flamingo. In Drosophila, the Fat and Dachsous cadherins also function in PCP, but in parallel to the core PCP components. C. elegans also have two Fat-like and one Dachsous-like cadherins, at least one of which, cdh-4, contributes to neural development. In C. elegans Wnt ligands and the conserved PCP genes have been shown to regulate a number of different events, including embryonic cell polarity, vulval morphogenesis, and cell migration. As is also observed in vertebrates, the Wnt and PCP genes appear to function to primarily provide information about the anterior to posterior axis of development. Here, we review the recent work describing how mutations in the Wnt and core PCP genes affect axon guidance and synaptogenesis in C. elegans.
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Affiliation(s)
- Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045
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Berto GE, Iobbi C, Camera P, Scarpa E, Iampietro C, Bianchi F, Gai M, Sgrò F, Cristofani F, Gärtner A, Dotti CG, Di Cunto F. The DCR protein TTC3 affects differentiation and Golgi compactness in neurons through specific actin-regulating pathways. PLoS One 2014; 9:e93721. [PMID: 24695496 PMCID: PMC3973554 DOI: 10.1371/journal.pone.0093721] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 03/06/2014] [Indexed: 01/10/2023] Open
Abstract
In neuronal cells, actin remodeling plays a well known role in neurite extension but is also deeply involved in the organization of intracellular structures, such as the Golgi apparatus. However, it is still not very clear which mechanisms may regulate actin dynamics at the different sites. In this report we show that high levels of the TTC3 protein, encoded by one of the genes of the Down Syndrome Critical Region (DCR), prevent neurite extension and disrupt Golgi compactness in differentiating primary neurons. These effects largely depend on the capability of TTC3 to promote actin polymerization through signaling pathways involving RhoA, ROCK, CIT-N and PIIa. However, the functional relationships between these molecules differ significantly if considering the TTC3 activity on neurite extension or on Golgi organization. Finally, our results reveal an unexpected stage-dependent requirement for F-actin in Golgi organization at different stages of neuronal differentiation.
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Affiliation(s)
- Gaia Elena Berto
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
- * E-mail: (GEB); (FDC)
| | - Cristina Iobbi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Paola Camera
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Elena Scarpa
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Corinne Iampietro
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Federico Bianchi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Marta Gai
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Francesco Sgrò
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Flavio Cristofani
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Annette Gärtner
- VIB Center for the Biology of Disease – VIB, Leuven, Belgium
| | - Carlos G. Dotti
- VIB Center for the Biology of Disease – VIB, Leuven, Belgium
- Centro de Biología Molecular Severo Ochoa, CSIC/UAM, Madrid, Spain
| | - Ferdinando Di Cunto
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
- * E-mail: (GEB); (FDC)
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Palanca A, Casafont I, Berciano MT, Lafarga M. Proteasome inhibition induces DNA damage and reorganizes nuclear architecture and protein synthesis machinery in sensory ganglion neurons. Cell Mol Life Sci 2013; 71:1961-75. [DOI: 10.1007/s00018-013-1474-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 09/02/2013] [Accepted: 09/10/2013] [Indexed: 11/24/2022]
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