CaMKII and Synaptic Plasticity
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Questions and Answers

What role does CaMKII play in the interaction with F-actin structures?

  • It stabilizes F-actin structures. (correct)
  • It inhibits F-actin polymerization.
  • It has no impact on F-actin structures.
  • It destabilizes F-actin structures.

    • How does CaMKII activity specifically impact synapse volumes after stimulation?

  • It leads to persistent increases in spine volume. (correct)
  • It decreases spine volume immediately.
  • It causes a transient increase in spine volume.
  • It has no effect on spine volume at all.

    • What characterizes the state of retinotectal synapses during early development?

  • They exhibit high levels of CaMKII activity.
  • They are rich in AMPA receptors.
  • They are primarily silent and lack AMPA receptors. (correct)
  • They show persistent activation of CaMKII.

    • What consequence arises from the activity-dependent binding of CaMKII to NR2B?

    <p>It triggers F-actin re-structuring and affects spine size.</p> Signup and view all the answers

    What is indicated by the transient activation of CaMKII observed after local glutamate uncaging?

    <p>It indicates specific increases in CaMKII activity at stimulated spines.</p> Signup and view all the answers

    What is the primary role of CaMKII in the context of learning and memory?

    <p>Modulating the structure and strength of synaptic connections</p> Signup and view all the answers

    Which of the following accurately describes the function of CREB?

    <p>It is involved in long-term potentiation and excitability modulation</p> Signup and view all the answers

    What distinguishes IEGs from other gene types in the context of synaptic activity?

    <p>They encode proteins that are immediate responses to neuronal activity</p> Signup and view all the answers

    Which statement about BDNF (Brain-Derived Neurotrophic Factor) is true?

    <p>It supports the survival and differentiation of neurons</p> Signup and view all the answers

    Regarding the postsynaptic density, which statement about CaMKII's presence is accurate?

    <p>CaMKII represents a small percentage (1-2%) of the brain's total protein content</p> Signup and view all the answers

    In the context of synaptic plasticity, what does 'engrams' refer to?

    <p>The physical manifestation of memory in neuron structures</p> Signup and view all the answers

    What is the primary mechanism through which CaMKII contributes to the late phase of long-term potentiation?

    <p>Through the phosphorylation of specific substrates leading to increased synaptic strength</p> Signup and view all the answers

    What is the primary function of CaMKII in the postsynaptic density?

    <p>It is involved in synaptic signaling and modulation.</p> Signup and view all the answers

    How many isoforms comprise the CaMKII family derived from the four genes?

    <p>28</p> Signup and view all the answers

    What role do the α- and β-subunits of CaMKII primarily play in the brain?

    <p>They are the predominant isoforms.</p> Signup and view all the answers

    What type of structure does CaMKII exhibit with its 12 subunits?

    <p>Two hexameric rings</p> Signup and view all the answers

    What is the key mechanism by which CaMKII maintains its activity?

    <p>It associates with calmodulin and calcium ions.</p> Signup and view all the answers

    Which of the following is NOT a role of CaMKII?

    <p>Generating new neuronal structures.</p> Signup and view all the answers

    What aspect of CaMKII allows it to bind anchoring proteins?

    <p>Association domain</p> Signup and view all the answers

    What modification does CaMKII carry out regarding Ca2+/calmodulin sensitivity?

    <p>Enhanced sensitivity</p> Signup and view all the answers

    Which of the following correctly describes the 'gate' function of CaMKII?

    <p>It regulates the association with the catalytic domain.</p> Signup and view all the answers

    What occurs within less than 1 second after a decrease in Ca2+ levels?

    <p>Calmodulin dissociates</p> Signup and view all the answers

    What mechanism allows for short-term persistent activation of CamKII?

    <p>Autophosphorylation of Thr286</p> Signup and view all the answers

    Under what condition does long-term persistent activation occur in the context of LTP?

    <p>Threshold number of kinase sites are phosphorylated</p> Signup and view all the answers

    What role does CamKII play in the context of LTP and synaptic transmission?

    <p>It enhances synaptic transmission</p> Signup and view all the answers

    What condition must be met for a CamKII persistent activity to decline?

    <p>Dephosphorylation of Thr286</p> Signup and view all the answers

    What happens during the perfusion of active CaMKII on CA1 pyramidal cells?

    <p>Increase in amplitude of spontaneous synaptic potentials</p> Signup and view all the answers

    What occurs when the rate of autophosphorylation exceeds dephosphorylation?

    <p>A long-lasting 'on' state of the switch is achieved</p> Signup and view all the answers

    What is suggested by increased transmission in the non-LTP group after perfusion of active CaMKII?

    <p>Occlusion between CaMKII-induced potentiation and LTP induction</p> Signup and view all the answers

    What is the predominant function of IEGs in the context of memory and learning?

    <p>They establish engrams related to LTP</p> Signup and view all the answers

    What is the primary subtype of NMDAR with which CaMKII associates?

    <p>NR2B</p> Signup and view all the answers

    What effect does calcium elevation have on CaMKII's association with F-actin?

    <p>It causes CaMKII to dissociate from F-actin.</p> Signup and view all the answers

    After CaMKII binds to NR2B, which of the following is true about its activity?

    <p>It remains active even after dissociation of Ca2+/calmodulin.</p> Signup and view all the answers

    What is one consequence of NR2B acting as a wedge in the autoinhibitory gate?

    <p>Prevention of secondary autophosphorylation at Thr305.</p> Signup and view all the answers

    Which site on GluR1 is specifically phosphorylated by CaMKII to enhance AMPA receptor conductance?

    <p>Ser831</p> Signup and view all the answers

    What role does the T site play in CaMKII activation after binding to NR2B?

    <p>It keeps the autoinhibitory gate open.</p> Signup and view all the answers

    What happens to CaMKII's activity after it phosphorylates AMPA receptors?

    <p>It enhances conductance at the synapse.</p> Signup and view all the answers

    Under resting conditions, what effect does F-actin have on CaMKII?

    <p>It sequesters CaMKII away from synapses.</p> Signup and view all the answers

    What is a significant function of CaMKII in synaptic mechanisms?

    <p>Enhancing channel conductance of AMPA receptors.</p> Signup and view all the answers

    Which of the following statements regarding CaMKII's activation is incorrect?

    <p>It is sensitive to phosphatase activity.</p> Signup and view all the answers

    Study Notes

    Molecular Basis of Synaptic Plasticity II

    • CamKII: Has a crucial role in learning and memory, contributing to synaptic plasticity
    • Structure and Function: Plays a key role in synaptic signaling and modulation.
    • Mechanisms: Mediates various processes contributing to synaptic function and plasticity.
    • Contribution to Learning and Memory: Central to the biological mechanisms underlying memory formation.

    CREB

    • Definition: Crucial in regulating gene expression in response to various signals, including those involved in learning and memory.
    • LTP and Synaptic Capture: Critical to understanding long-term synaptic plasticity, a key element in learning.
    • Excitability: Aids in regulating neuron excitability and synaptic strength.

    IEGs

    • Definition: A category of genes with rapid and transient expression in response to external stimuli.
    • Engrams and LTP: IEGs are critical to long-term memory formation, a significant aspect of synaptic plasticity.
    • Excitability: Affects the excitatory properties of neurons.
    • Arc and a novel mode of transmission: Arc facilitates the establishment of long-term memory, using a unique pathway for information transfer.

    BDNF

    • Definition: Regulates various aspects of neuronal function and plasticity.
    • BDNF can Induce LTP: A key regulator of LTP induction, it contributes to memory formation.
    • Necessary for Spatial Learning: Essential for spatial learning, showing its crucial role in memory processes.

    CamKII Activation States

    • Brief Activation: No autophosphorylation, short-lived effect.
    • Short-term Persistent Activation: Autophosphorylation, lasting activation even after calcium levels decrease.
    • Long-term Persistent Activation: Very prolonged activation, achieved by a rate of autophosphorylation dominating the dephosphorylation process. This is important for long-term memory.

    From LTP to CaMKII

    • Pathways in the Schaffer collateral pathway: Illustrates the complex interactions between CREB, MAPK, PKA, protein phosphatase 1, and other signaling molecules during synaptic plasticity.
    • Role of Modulatory Inputs (e.g., dopamine): External influences on these complex pathways, influencing synaptic activity and plasticity.

    CAMKII Structure

    • Structure and Classification: The details of multiple protein isoforms derived from four genes (alpha, beta, gamma and delta) are elaborated. Importance of each subunit to overall function.
    • Catalytic and Regulatory Domains: Essential structural details, catalytic/regulatory domains forming hexameric rings and the gear-shaped association domain, which influence catalytic function.

    Mechanisms to Impact Transmission

    • Association with NMDARs: Interactions with NMDA receptors, particularly NR2B, are primary mechanisms.
    • Phosphorylation of AMPARs: The phosphorylation of AMPA receptors (especially at Ser831 on GluR1) is extensively described.
    • Regulation of AMPAR Trafficking: The process of regulating AMPA receptor movement to and from synapses is elaborated, using proteins like SAP97 and Myosin VI
    • Regulation of Function and Trafficking of AMPARs: The roles of SAP97/Myosin VI and Stargazer proteins in regulating AMPA receptors are outlined.
    • Regulation of spine size: Specific pathways influence spine size via interaction of CaMKII with F-actin.

    CamKII in vivo: Synaptic Maturation

    • Early Development and Synaptic Function: Details how synapses operate during early development in vivo.
    • Activity-dependent Changes: The effects of activity on synapse function.

    CREB Inhibition Leads to Long-term Deficits

    • Long-Term vs. Short-Term Memory Involvement: Illustrates differing effects on long-term and short-term memory.
    • CREB Mutations and Memory: Details the consequences of disrupting CREB activity on memory consolidation or reconsolidation via genetic manipulation.
    • CREB Activation Mechanisms: Describe mechanisms by which CREB is often activated in response to incoming signals.

    Immediate Early Genes (IEGs)

    • Quick Expression and Turnover: Highlight IEGs as rapidly expressed genes which have short half-lives.
    • Pattern of Activity Leading to IEG Expression: The relationship between synaptic activity and the expression of specific IEGs is detailed.

    Engrams and the Locus of Memory

    • Historical Perspectives: Provides historical context and background on concepts of memory representations.
    • Mechanisms of Memory Consolidation Evidence: Evidence relating to the physical location of long term memory.
    • Key Figures in Memory Research: Highlights important figures in memory research.

    BDNF

    • Neurotrophic Factor Properties: The details of a particular neurotrophin, its effects on various processes (proliferation, survival, repair, and plasticity) during neuronal development, and its implications for plasticity during development.
    • BDNF and LTP: Show how BDNF contributes to long-term potentiation by inducing relevant proteins.
    • BDNF and Spatial Learning: Details the specific role of BDNF as a key factor for spatial learning.

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    Description

    This quiz explores the multifunctional role of CaMKII in synaptic plasticity, with a focus on its interactions with F-actin structures and implications for learning and memory. Questions delve into various mechanisms, including the activity-dependent binding to NR2B, the role of CREB, and the significance of IEGs. Test your understanding of these critical neurobiological processes.

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