scholarly journals Polarization and Myelination in Myelinating Glia

2012 ◽  
Vol 2012 ◽  
pp. 1-28 ◽  
Author(s):  
Toshihiro Masaki
Keyword(s):  
Nervous System ◽  
Epithelial Cells ◽  
Schwann Cells ◽  
Myelin Sheath ◽  
Nerve Impulse ◽  
Membrane System ◽  
Cell Types ◽  
Cell Polarization ◽  
Polarization Study ◽  
Myelinating Glia

Myelinating glia, oligodendrocytes in central nervous system and Schwann cells in peripheral nervous system, form myelin sheath, a multilayered membrane system around axons enabling salutatory nerve impulse conduction and maintaining axonal integrity. Myelin sheath is a polarized structure localized in the axonal side and therefore is supposed to be formed based on the preceding polarization of myelinating glia. Thus, myelination process is closely associated with polarization of myelinating glia. However, cell polarization has been less extensively studied in myelinating glia than other cell types such as epithelial cells. The ultimate goal of this paper is to provide insights for the field of myelination research by applying the information obtained in polarity study in other cell types, especially epithelial cells, to cell polarization of myelinating glia. Thus, in this paper, the main aspects of cell polarization study in general are summarized. Then, they will be compared with polarization in oligodendrocytes. Finally, the achievements obtained in polarization study for epithelial cells, oligodendrocytes, and other types of cells will be translated into polarization/myelination process by Schwann cells. Then, based on this model, the perspectives in the study of Schwann cell polarization/myelination will be discussed.

Septins in the glial cells of the nervous system

2014 ◽  
Vol 395 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Julia Patzig ◽  
Michelle S. Dworschak ◽  
Ann-Kristin Martens ◽  
Hauke B. Werner
Keyword(s):  
Nervous System ◽  
Schwann Cells ◽  
Glial Cells ◽  
Current Knowledge ◽  
Cell Types ◽  
Higher Order ◽  
Neuralgic Amyotrophy ◽  
Cellular Processes ◽  
Functional Relevance ◽  
Order Structures

Abstract The capacity of cytoskeletal septins to mediate diverse cellular processes is related to their ability to assemble as distinct heterooligomers and higher order structures. However, in many cell types the functional relevance of septins is not well understood. This minireview provides a brief overview of our current knowledge about septins in the non-neuronal cells of the vertebrate nervous system, collectively termed ‘glial cells’, i.e., astrocytes, microglia, oligodendrocytes, and Schwann cells. The dysregulation of septins observed in various models of myelin pathology is discussed with respect to implications for hereditary neuralgic amyotrophy (HNA) caused by mutations of the human SEPT9-gene.

Composition and function of PDZ protein complexes during cell polarization

2003 ◽  
Vol 285 (3) ◽  
pp. F377-F387 ◽  
Author(s):  
Michael H. Roh ◽  
Ben Margolis
Keyword(s):  
Epithelial Cells ◽  
Current Knowledge ◽  
Protein Complexes ◽  
Cell Types ◽  
Cell Polarization ◽  
Differential Distribution ◽  
Pdz Proteins ◽  
Homologous Protein ◽  
Pdz Protein ◽  
And Function

Complexes consisting of PDZ proteins have been implicated in a variety of cellular processes. In recent years, it has become increasingly clear that PDZ proteins play essential roles during the establishment of spatial asymmetry in various metazoan cell types such as epithelial cells. Epithelial cells possess asymmetry with respect to the apicobasal axis reflected by the differential distribution of proteins and lipids in the apical and basolateral surfaces. In Drosophila, three PDZ protein complexes have been shown to play crucial functions during the establishment of cell-cell adhesions and epithelial cell polarity: Bazooka/Dm-Par6/DaPKC, Crumbs/Stardust/Discs Lost, and Scribble/Discs Large/Lethal Giant Larvae. In this review, we focus primarily on our current knowledge of the localization and function of these complexes in Drosophila epithelia. We also discuss recent data that enhance our understanding of the homologous protein complexes and their roles during junctional assembly and polarization of mammalian epithelial cells.

scholarly journals An Autoradiographic Study of Nucleic Acid and Protein Turnover in the Mammalian Neuraxis

1958 ◽  
Vol 4 (6) ◽  
pp. 785-792 ◽  
Author(s):  
Harold Koenig
Keyword(s):  
Nervous System ◽  
Nucleic Acids ◽  
Schwann Cells ◽  
Protein Turnover ◽  
Nuclear Dna ◽  
Intrathecal Injection ◽  
Cell Types ◽  
Autoradiographic Study ◽  
Nerve Cells ◽  
Ependymal Lining

The turnover of nucleic acids and proteins in the central nervous system has been explored by autoradiography following the subarachnoid injection of tagged precursors. Nuclear PNA of neurons and oligodendrocytes becomes radioactive earlier than cytoplasmic PNA after injection of adenine-C14 and orotic-C14 acid. By 24 hours following injection, cytoplasmic PNA is radioactive. Radioactivity persists with little decrease for as long as 51 days after an injection of adenine-C14. The cells of the ependymal lining, choroidal plexus, leptomeninges, blood vessel walls, and Schwann cells also exhibit radioactivity in PNA as judged by the loss of radioactivity following ribonuclease digestion. From the 3rd day on, increasing numbers of the aforementioned cells, with the exception of nerve cells, exhibit ribonuclease-resistant nuclear radioactivity which is abolished by deoxyribonuclease. This radioactivity indicates labelling of nuclear DNA. Following the intrathecal injection of methionine-S35 and glycine-2-H3, nerve cells, oligodendrocytes, cells of ependymal lining, choroidal plexus, leptomeninges, blood vessels, and Schwann cells become radioactive. Nerve cells lose most of their radioactivity within a few hours, first from the cytoplasm and later from the nucleus. Other cell types retain their radioactivity for considerable periods of time. Although astrocytes, microglia, and satellite cells of sensory ganglia do not appear to incorporate labelled precursors into nucleic acids or proteins, reacting phagocytic microglia actively take up labelled amino acids. These results are discussed with particular reference to PNA and protein turnover in nerve cells, oligodendrocytes, and Schwann cells. It is believed that these metabolic activities in neurons are concerned in part with the elaboration of axoplasmic proteins. The nucleoprotein metabolism of oligodendrocytes and Schwann cells may be related to myelin biosynthesis both in the immature and the mature nervous system.

scholarly journals Tight junctions in Schwann cells of peripheral myelinated axons

2005 ◽  
Vol 169 (3) ◽  
pp. 527-538 ◽  
Author(s):  
Tatsuo Miyamoto ◽  
Kazumasa Morita ◽  
Daisuke Takemoto ◽  
Kosei Takeuchi ◽  
Yuka Kitano ◽  
...  
Keyword(s):  
Nervous System ◽  
Epithelial Cells ◽  
Tight Junction ◽  
Adhesion Molecules ◽  
Schwann Cells ◽  
Nerve Conduction ◽  
Physiological Function ◽  
Node Of Ranvier ◽  
Behavioral Abnormalities ◽  
Deficient Mice

Tight junction (TJ)–like structures have been reported in Schwann cells, but their molecular composition and physiological function remain elusive. We found that claudin-19, a novel member of the claudin family (TJ adhesion molecules in epithelia), constituted these structures. Claudin-19–deficient mice were generated, and they exhibited behavioral abnormalities that could be attributed to peripheral nervous system deficits. Electrophysiological analyses showed that the claudin-19 deficiency affected the nerve conduction of peripheral myelinated fibers. Interestingly, the overall morphology of Schwann cells lacking claudin-19 expression appeared to be normal not only in the internodal region but also at the node of Ranvier, except that TJs completely disappeared, at least from the outer/inner mesaxons. These findings have indicated that, similar to epithelial cells, Schwann cells also bear claudin-based TJs, and they have also suggested that these TJs are not involved in the polarized morphogenesis but are involved in the electrophysiological “sealing” function of Schwann cells.

scholarly journals Transcriptional Regulators of the Golli/Myelin Basic Protein Locus Integrate Additive and Stealth Activities

2020 ◽  
Author(s):  
Hooman Bagheri ◽  
Hana Friedman ◽  
Kathy Siminovitch ◽  
Alan Peterson
Keyword(s):  
Nervous System ◽  
Myelin Basic Protein ◽  
Schwann Cells ◽  
Basic Protein ◽  
Cell Types ◽  
Myelin Proteins ◽  
Transcriptional Unit ◽  
Individual Autonomy ◽  
Specific Gene ◽  
Regulatory Sequences

ABSTRACTMyelin is composed of plasma membrane spirally wrapped around axons and compacted into dense sheaths by myelin associated proteins. In the central nervous system (CNS), myelin is elaborated by neuroepithelial derived oligodendrocytes and in the peripheral nervous system (PNS) by neural crest derived Schwann cells. While some myelin proteins are unique to only one lineage, myelin basic protein (Mbp) is expressed in both. Overlapping the Mbp gene is Golli, a transcriptional unit that is expressed widely both within and beyond the nervous system. A super-enhancer domain within the Golli/Mbp locus contains multiple enhancers shown previously to drive reporter construct expression specifically in oligodendrocytes or Schwann cells. In order to determine the contribution of each enhancer to the Golli/Mbp expression program and examine if interactions among these enhancers occur, we derived mouse lines in which enhancers were deleted, either singly or in different combinations, and relative mRNA accumulation was measured at key stages of development. Although super-enhancers have been shown to facilitate interaction among their component enhancers, the enhancers investigated here demonstrated functions that were largely additive. However, enhancers demonstrating autonomous activity strictly in one cell lineage, when missing, were found to significantly reduce output in the other thus revealing cryptic “stealth” activity. Further, Golli accumulation in all cell types investigated was markedly and uniformly attenuated by the absence of a key oligodendrocyte enhancer. Our observations expose a novel level of enhancer interaction and are consistent with a model in which enhancer-mediated DNA looping underlies higher-order Golli/Mbp regulatory organization.AUTHOR SUMMARYThe control of transcription is mediated through regulatory sequences that engage in a lineage and developmentally contextual manner. The Golli/Mbp locus gives rise to several mRNAs and while Mbp mRNAs accumulate exclusively in the two glial cell types that elaborate myelin, Golli mRNAs accumulate in diverse cell types both within and beyond the nervous system. To determine how the different Golli/Mbp enhancers distribute their activities and to reveal if they operate as autonomous agents or have functionally significant interactions with each other we derived multiple enhancer knock-out lines. Comparing the developmental accumulation of Mbp and Golli mRNAs revealed that the autonomous targeting capacity of multiple enhancers accurately predicted their in-situ contributions. Also, they acted in a largely additive manner indicating significant individual autonomy that can be accounted for by a simple chromatin looping model. Unexpectedly, we also uncovered cryptic “stealth” activity emanating from these same enhancers in lineages where they show no autonomous targeting capacity thus providing new insight into the control of lineage specific gene expression.

scholarly journals Pathomechanisms in schwannoma development and progression

Oncogene ◽  
2020 ◽  
Vol 39 (32) ◽  
pp. 5421-5429 ◽  
Author(s):  
Dario-Lucas Helbing ◽  
Alexander Schulz ◽  
Helen Morrison
Keyword(s):  
Extracellular Matrix ◽  
T Cells ◽  
Nervous System ◽  
Tumor Microenvironment ◽  
Tumor Suppressor ◽  
Tumor Suppressor Gene ◽  
Schwann Cells ◽  
Cell Types ◽  
Suppressor Gene ◽  
Different Cell Types

Abstract Schwannomas are tumors of the peripheral nervous system, consisting of different cell types. These include tumorigenic Schwann cells, axons, macrophages, T cells, fibroblasts, blood vessels, and an extracellular matrix. All cell types involved constitute an intricate “tumor microenvironment” and play relevant roles in the development and progression of schwannomas. Although Nf2 tumor suppressor gene-deficient Schwann cells are the primary tumorigenic element and principle focus of current research efforts, evidence is accumulating regarding the contributory roles of other cell types in schwannoma pathology. In this review, we aim to provide an overview of intra- and intercellular mechanisms contributing to schwannoma formation. “Genes load the gun, environment pulls the trigger.” -George A. Bray

scholarly journals Myosin II has distinct functions in PNS and CNS myelin sheath formation

2008 ◽  
Vol 182 (6) ◽  
pp. 1171-1184 ◽  
Author(s):  
Haibo Wang ◽  
Ambika Tewari ◽  
Steven Einheber ◽  
James L. Salzer ◽  
Carmen V. Melendez-Vasquez
Keyword(s):  
Nervous System ◽  
Schwann Cells ◽  
Myelin Sheath ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Myelin Formation ◽  
Sheath Formation ◽  
Central Nervous Systems ◽  
Glial Membrane ◽  
Cytoskeleton Dynamics

The myelin sheath forms by the spiral wrapping of a glial membrane around the axon. The mechanisms responsible for this process are unknown but are likely to involve coordinated changes in the glial cell cytoskeleton. We have found that inhibition of myosin II, a key regulator of actin cytoskeleton dynamics, has remarkably opposite effects on myelin formation by Schwann cells (SC) and oligodendrocytes (OL). Myosin II is necessary for initial interactions between SC and axons, and its inhibition or down-regulation impairs their ability to segregate axons and elongate along them, preventing the formation of a 1:1 relationship, which is critical for peripheral nervous system myelination. In contrast, OL branching, differentiation, and myelin formation are potentiated by inhibition of myosin II. Thus, by controlling the spatial and localized activation of actin polymerization, myosin II regulates SC polarization and OL branching, and by extension their ability to form myelin. Our data indicate that the mechanisms regulating myelination in the peripheral and central nervous systems are distinct.

scholarly journals Ion Channels in Epithelial Dynamics and Morphogenesis

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2280
Author(s):  
Ankit Roy Choudhury ◽  
Jörg Großhans ◽  
Deqing Kong
Keyword(s):  
Nervous System ◽  
Ion Channels ◽  
Epithelial Cells ◽  
Cell Types ◽  
Mechanical Forces ◽  
Morphogenetic Movements ◽  
Mechanosensitive Ion Channels ◽  
Channel Proteins ◽  
Epithelial Tissues

Mechanosensitive ion channels mediate the neuronal sensation of mechanical signals such as sound, touch, and pain. Recent studies point to a function of these channel proteins in cell types and tissues in addition to the nervous system, such as epithelia, where they have been little studied, and their role has remained elusive. Dynamic epithelia are intrinsically exposed to mechanical forces. A response to pull and push is assumed to constitute an essential part of morphogenetic movements of epithelial tissues, for example. Mechano-gated channels may participate in sensing and responding to such forces. In this review, focusing on Drosophila, we highlight recent results that will guide further investigations concerned with the mechanistic role of these ion channels in epithelial cells.

scholarly journals Coherent directed movement toward food modeled in Trichoplax, a ciliated animal lacking a nervous system

2019 ◽  
Vol 116 (18) ◽  
pp. 8901-8908 ◽  
Author(s):  
Carolyn L. Smith ◽  
Thomas S. Reese ◽  
Tzipe Govezensky ◽  
Rafael A. Barrio
Keyword(s):  
Nervous System ◽  
Epithelial Cells ◽  
Cell Types ◽  
Lower Surface ◽  
Marine Animal ◽  
Directed Movement ◽  
Trichoplax Adhaerens ◽  
Modeling Behavior ◽  
Multicellular Organisms ◽  
Ciliated Epithelial Cells

Trichoplax adhaerens is a small, ciliated marine animal that glides on surfaces grazing upon algae, which it digests externally. It has no muscles or nervous system and only six cell types, all but two of which are embedded in its epithelium. The epithelial cells are joined by apical adherens junctions; neither tight junctions nor gap junctions are present. Monociliated epithelial cells on the lower surface propel gliding. The cilia beat regularly, but asynchronously, and transiently contact the substrate with each stroke. The animal moves in random directions in the absence of food. We show here that it exhibits chemotaxis, moving preferentially toward algae embedded in a disk of agar. We present a mathematical model to explain how coherent, directional movements could arise from the collective actions of a set of ciliated epithelial cells, each independently sensing and responding to a chemoattractant gradient. The model incorporates realistic values for viscoelastic properties of cells and produces coordinated movements and changes in body shape that resemble the actual movements of the animal. The model demonstrates that an animal can move coherently in search of food without any need for chemical signaling between cells and introduces a different approach to modeling behavior in primitive multicellular organisms.

scholarly journals White Matter Repair: Skin-Derived Precursors as a Source of Myelinating Cells

2010 ◽  
Vol 37 (S2) ◽  
pp. S34-S41 ◽  
Author(s):  
Jeff Biernaskie ◽  
Freda D. Miller
Keyword(s):  
Nervous System ◽  
Stem Cell ◽  
Peripheral Nervous System ◽  
Schwann Cells ◽  
Cell Types ◽  
Functional Restoration ◽  
Neurological Injury ◽  
Great Promise ◽  
Biological Origin ◽  
Mesodermal Cell

ABSTRACT:Stem cell based therapies hold great promise for repair and functional restoration following neurological injury and disease. Skin-derived precursors (or “SKPs”) are a novel, multipotent somatic stem cell that resides within the mammalian dermis. SKPs persist within the skin throughout adulthood and yet intriguingly, exhibit many similarities to embryonic neural crest stem cells (NCSCs). For example, SKPs give rise to both neural and mesodermal cell types, and the former appear biased to peripheral nervous system fates. As such, SKPs are capable of generating Schwann cells, the myelinating glial cell of the peripheral nervous system. Here we discuss our current understanding of the biological origin of SKPs and specifically the potential therapeutic utility of SKPs as a highly accessible and autologous source of Schwann cells for remyelination and repair of the injured or diseased nervous system.

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