Synaptogenesis

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Synaptogenesis
Illustrations from Development of the Nervous
System/ Sanes, Rea, Harris
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Morphological evidences detectable just in
relative advance stage of synapse formation -
EM.
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Growth cone filopodia Axon (presynaptic
terminal) Dendritic filopodia Dendrite (PSD)
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Physiological evidences Synapse function
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Synapse functional maturation Presence of
neurotransmitter synthesis and release machinery
Before synaptogenesis. Neurotransmitter release
occur before synapse formation Mechanism
mostly vesicular.
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Ca dependency Growth cone And Synapse (at all
ages)
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Adhesion
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From growth cone to presynaptic terminal
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The elements of the PNS synapses
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Innervation of muscle cell by the motor neuron
induces Increase in the number of receptors
Increase in the amount of receptors
clustering Specificity
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Agrin binds to a receptor complex and MaSK is
required for clustering
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The elements of the CNS synapses
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EphB signaling influences Glutamate receptors
aggregation In the CNS
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Eph -Rs
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Murai et al, 2003
Eph A3 on astrocyte red Synaptophysin
blue YFP- dendritic spine - green
A role of astrocyte in The regulation of spine
shape
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White glut application Yellow size of
synaptic currents Green synaptic contacts
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Neural activity
Regulation of receptor expression Regulation of
post and presynaptic transcription Synaptic
strength
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Activity dependent ..
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Receptors subunits regulation with age In all
receptor types Depends on Age Brain region
Activity Chemiacl interactions (trophic factors)
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Glutamatergic synapse maturation
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Hippocampal slice b-catenin Activity dependent
remodeling
B-Catenin
Cadherin
Murase et al., 2002
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Hippocampal neuronal culture b-catenin Activity
dependent remodeling
b-catenin accumulation in the spine Following
KCl depolarization

• NMDA dependent
• The interaction between Catenin and Cadherin
• depends on the activity of tyrosine posphatase
• 3. Single amino acid activity

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Phe-no phosphorilation Glu - phosphorilation
Functional effect of the tyr phosphorilation Is
reflected in nEPSC activity No change in mEPSC
amplitude Increase in mEPSC frequency
Presynaptic effect neurotransmitter release
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Role of Cadherin in synaptogenesis and synaptic
plasticity
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Activity dependent synaptic plasticity
M.M Poo, 2002