Phosphoinositide metabolism in synaptic vesicle recycling

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1. Phosphoinositide metabolism in synaptic vesicle
   recycling
2. Techniques in synaptic vesicle recycling

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Vesicle pools
Morphologically, vesicles are classified as
docked or undocked. Docked vesicles are further
subdivided into primed and unprimed pools
depending on whether they are competent to fuse
when cells stimulated.
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SNARE complex and Ca2 sensor
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Steps of clathrin-mediated endocytosis
Splenv De Camilli, 2000

• Invagination to create curvature.
• Fission to separate the vesicle.
• Uncoating to form a real vesicle.

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Endocytic invagination mediated by BAR-domain
containing protein
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Clathrin is critical to maintain the curvature of
endocytic vesicle
Hinrichsen et al., 2006
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Clathrin-mediated endocytosis
Endocytic invagination

• Bar-domain containing protein such as amphiphysin
  is critical for invagination by inducing membrane
  curvature
• Clathrin, which is recruited by AP-2, is critical
  in maintaining the curvature of endocytic vesicles

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Dynamin is important for pinch-off of endocytic
vesicle
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Reconstruction of dynamin 1 knockout synapse from
electron tomography data.
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Synaptojanin 1 is critical for vesicle uncoating
Hayashi et al., 2008
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Clathrin-mediated endocytosis
Endocytic invagination

1. Bar-domain containing protein such as amphiphysin
   which inducing membrane curvature
2. Clathrin, which is recruited by AP-2, is critical
   in maintaining the curvature of endocytic vesicles

Pinch-off Dynamin
Vesicle uncoating Synaptojanin 1 that
hydrolyzes PI(4,5)P2
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Clathrin-mediated endocytosis is a slow form of
endocytosis
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Full fusion and kiss-and-run
Harata et al, J Neurochem 2006
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1. Phosphoinositide metabolism in synaptic vesicle
   recycling
2. Techniques in synaptic vesicle recycling

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PI(4,5)P2 concentrates on the plasma membrane
PI(4,5)P2

• Functions of PI(4,5)P2
• Exocytosis and endocytosis
• Ion channel regulation
• Cell adhesion
• Signal transduction
• Actin polymerization/cell motility

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Coupling between PI(4,5)P2 metabolism and
synaptic vesicle recycling
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Ca2 dependent interaction between synaptotagmin
and PI(4,5)P2
Schiavo et al, PNAS 1996
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Coupling between PI(4,5)P2 metabolism and
synaptic vesicle recycling
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Exocytosis defect in PIPK I? KO neuron
Di Paolo et al, Nature 2004
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Importance of lipids in endocytosis
Splenv De Camilli, 2000

• Invagination to create curvature.
• Fission to separate the vesicle.
• Uncoating to form a real vesicle.

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PI(4,5)P2 metabolism is coupled to synaptic
vesicle recycling
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Coupling between PI(4,5)P2 metabolism and
synaptic vesicle recycling