Module 10.2
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Questions and Answers

What is the primary focus of Franklin and Ffrench-Constant's review?

  • The structure of compact myelin
  • Mechanisms and experimental medicines for regenerating CNS myelin (correct)
  • The plasticity of myelin
  • The morphology of myelin and myelination

    • In Rio-Hortega’s drawings revisited with fluorescent protein, what did the fluorescent protein define?

  • The structure of compact myelin
  • The morphology of myelin and myelination
  • A cytoplasm-filled channel system of CNS myelin (correct)
  • The plasticity of myelin

    • According to Tim Kennedy, what does compact myelin look like under transmission electron microscopy?

  • Network
  • Amorphous solid
  • Gel
  • Crystal (correct)

    • What is the primary focus of Cedric S Raine's work?

    <p>Morphology of myelin and myelination</p> Signup and view all the answers

    According to de Faria et al., what shapes brain function and plasticity?

    <p>Periods of synchronized myelin changes</p> Signup and view all the answers

    What are the tiny dots and bigger dots observed in compact myelin under transmission electron microscopy?

    <p>Tiny dots - intermediate filaments, Bigger dots - microtubules</p> Signup and view all the answers

    What are the four types of myelin plasticity mentioned in the text?

    <p>Myelination of previously unmyelinated axons, Elongation of existing myelin, Retraction of existing myelin, Thinner or thicker existing myelin</p> Signup and view all the answers

    What occurs with the loss of DCC from myelinating oligodendrocytes?

    <p>Detachment of glial loops and leakage of caspr out of the paranode</p> Signup and view all the answers

    What is observed with selective cell type deletion of UNC5B from oligodendrocytes?

    <p>Everted paranodal loops and reduced levels of tight junction protein claudin 11</p> Signup and view all the answers

    What occurs with the loss of Periaxin in humans or mouse?

    <p>Loss of Cajal bands, reduces internode length, and slows the rate of conduction velocity</p> Signup and view all the answers

    What is the role of mitochondria in myelin maintenance?

    <p>Mitochondria migrate through channels within the myelin sheath to support myelin maintenance</p> Signup and view all the answers

    What distinguishes non-compacted PNS myelin from CNS myelin?

    <p>Non-compacted PNS myelin features paranodal loops, Cajal bands, and Schmidt-Lantermann incisures</p> Signup and view all the answers

    What is observed with loss of oligodendrocyte expression of DCC?

    <p>Increased myelin outfoldings and reduced compact myelin proteins</p> Signup and view all the answers

    What happens with disruption of loop-loop autotypic junctions due to UNC5B deletions from oligodendrocytes?

    <p>Gaps in compact myelin and disruption of connection between paranodal loops</p> Signup and view all the answers

    What is the impact of loss of DCC from myelinating oligodendrocytes on myelin function?

    <p>Deficits in coordination and balance, reduced conduction velocity, and progressively worse myelin disruption with aging</p> Signup and view all the answers

    What is the role of the cell body in mature CNS myelin?

    <p>The cell body communicates with and supports the paranodal loops and the compact myelin</p> Signup and view all the answers

    What is the crucial role of gNetrin-1 and DCC knockout in neonatal development?

    <p>Leads to neonatal death</p> Signup and view all the answers

    What is the function of CASPR in myelin?

    <p>Acts as a molecular fence, segregating potassium and sodium channels</p> Signup and view all the answers

    What is the role of Schwann cells in myelination?

    <p>Migration and wrapping of axons to form paranodal junctions</p> Signup and view all the answers

    What is the critical step in the formation of mature nodes of Ranvier?

    <p>Consolidation of the Caspr spiral</p> Signup and view all the answers

    What is the role of Claudin 11 in myelin?

    <p>Plays a role in paranodal maintenance</p> Signup and view all the answers

    Where are Netrin-1 and DCC expressed and enriched?

    <p>Oligodendrocytes and CNS paranodes</p> Signup and view all the answers

    What is the impact of disruption of paranodal maintenance in DCC or netrin-1 knockout models?

    <p>Impacts the organization of specialized axonal domains</p> Signup and view all the answers

    What do autotypic tight junctions and gap junctions form?

    <p>Cell-cell junctions linking paranodal loops</p> Signup and view all the answers

    What is the result of the disruption of loop-loop autotypic junctions due to UNC5B deletions from oligodendrocytes?

    <p>Disruption of paranodal junctions and specialized axonal domains</p> Signup and view all the answers

    Which protein is essential for labeling paranodal junctions?

    <p>CASPR</p> Signup and view all the answers

    What is the consequence of genetic deletion of Caspr, NF155, or contactin?

    <p>Disruption of paranodal junctions and specialized axonal domains</p> Signup and view all the answers

    What is the role of Netrin-1 and DCC in CNS paranodes?

    <p>Influencing paranodal maintenance</p> Signup and view all the answers

    What is the consequence of disruption of paranodal maintenance in DCC or netrin-1 knockout models?

    <p>Impacts the organization of specialized axonal domains</p> Signup and view all the answers

    Which proteins are enriched at CNS paranodes and influence paranodal maintenance?

    <p>Netrin-1 and DCC</p> Signup and view all the answers

    What is the critical step in the formation of mature nodes of Ranvier?

    <p>Consolidation of the Caspr spiral</p> Signup and view all the answers

    Which proteins are essential for anchoring paranodal loops to the axon and to each other?

    <p>Tight junctions and gap junctions</p> Signup and view all the answers

    What gives myelin a dynamic appearance?

    <p>Attachment sites</p> Signup and view all the answers

    What is the role of CASPR in preventing short circuits?

    <p>Segregating potassium and sodium channels</p> Signup and view all the answers

    Study Notes

    Organization and Specialization of Myelin and Axonal Domains

    • The knockout of gNetrin-1 and DCC leads to neonatal death, indicating their crucial role in development.
    • The attachment sites in myelin give it a dynamic appearance, and proteins such as CASPR are essential for labeling paranodal junctions.
    • CASPR acts as a molecular fence, segregating potassium and sodium channels to prevent short circuits.
    • Schwann cells play a vital role in myelination, as seen in the migration and wrapping of axons to form paranodal junctions.
    • The development of myelin involves the consolidation of paranodal loops and the segregation of sodium and potassium channels.
    • The consolidation of the Caspr spiral is a critical step in the formation of mature nodes of Ranvier.
    • The model of myelin biogenesis illustrates the development and compaction of the myelin sheath around the axon.
    • Specific cell-cell junctions, including tight junctions and gap junctions, anchor paranodal loops to the axon and to each other.
    • Genetic deletion of Caspr, NF155, or contactin results in disruption of paranodal junctions and specialized axonal domains, affecting conduction velocity and balance.
    • Autotypic tight junctions and gap junctions form cell-cell junctions linking paranodal loops, and Claudin 11 plays a role in paranodal maintenance.
    • Netrin-1 and DCC are expressed by oligodendrocytes and are enriched at CNS paranodes, influencing paranodal maintenance.
    • Disruption of paranodal maintenance in DCC or netrin-1 knockout models impacts the organization of specialized axonal domains.

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    Kennedy Glia and Myelination 2023 Part 2 PDF

    Description

    Test your knowledge of myelin and axonal domain organization with this quiz. Explore the implications of DCC and UNC5B loss in myelinating oligodendrocytes, as well as the role of specific proteins and genetic deletions in maintaining specialized axonal domains. Understand the impact on conduction velocity, myelin disruption, and CNS myelin function.

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