Download - Phosphoinositide metabolism in synaptic vesicle recycling Techniques in synaptic vesicle recycling
1. Phosphoinositide metabolism in synaptic vesicle recycling
2. Techniques in synaptic vesicle recycling
Docking
Priming Ca2+
Fusion
Vesicle reserve
Pre-
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.
Munc-18
Munc-13
SNARE complex
SNARE complex and Ca2+ sensor
Invagination Constriction
UncoatingFission
Steps of clathrin-mediated endocytosis
• Invagination to create curvature.
• Fission to separate the vesicle.
• Uncoating to form a real vesicle.
Splenv & De Camilli, 2000
Endocytic invagination mediated by BAR-domain containing protein
Peter et al., 2003
Clathrin is critical to maintain the curvature of endocytic vesicle
Hinrichsen et al., 2006
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
Clathrin-mediated endocytosis
Dynamin is important for pinch-off of endocytic vesicle
Reconstruction of dynamin 1 knockout synapse from electron tomography data.
Hayashi et al., 2008
Synaptojanin 1 is critical for vesicle uncoating
Endocytic invagination1. 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
Clathrin-mediated endocytosis
Pinch-off: Dynamin
Vesicle uncoating:
Synaptojanin 1 that hydrolyzes PI(4,5)P2
Clathrin-mediated endocytosis is a slow form of
endocytosis
Full fusion and kiss-and-run
Harata et al, J Neurochem 2006
1. Phosphoinositide metabolism in synaptic vesicle recycling
2. Techniques in synaptic vesicle recycling
PI(4,5)P2 concentrates on the plasma membrane
PI(4,5)PPI(4,5)P22
PI(3)PPI(3)PPI(3,4,5)PPI(3,4,5)P33
PI(4)PPI(4)PPI(3,5)PPI(3,5)P22
PI(4,5)P2
Functions of PI(4,5)P2:
•Exocytosis and endocytosis
•Ion channel regulation
•Cell adhesion
•Signal transduction
•Actin polymerization/cell motility
Coupling between PI(4,5)P2 metabolism and synaptic vesicle recycling
PI(4)P PI(4,5)P2
KinasesPI(4,5)P2 PI(4)P
phosphatases
Ca2+ dependent interaction between synaptotagmin and PI(4,5)P2
Schiavo et al, PNAS 1996
Ca2+
Endocytosis.org
PI(4)P PI(4,5)P2
KinasesPI(4,5)P2 PI(4)P
phosphatases
Coupling between PI(4,5)P2 metabolism and synaptic vesicle recycling
Type I PI(4)P 5-kinase:PIPK IαPIPK IβPIPK Iγ
PI(4)P PI(4,5)P2Kinases
Exocytosis defect in PIPK Iγ KO neuron
Di Paolo et al, Nature 2004
PIPK Iγ
mEPSCs in cultured neurons
Invagination Constriction
UncoatingFission
Importance of lipids in endocytosis
• Invagination to create curvature.
• Fission to separate the vesicle.
• Uncoating to form a real vesicle.
Splenv & De Camilli, 2000
PI(4,5)P2 metabolism is coupled to synaptic vesicle recycling
PI(4)P PI(4,5)P2
KinasesPI(4,5)P2 PI(4)P and PI
Phosphatases
Synaptojanin 1 is a main phosphatase for PI(4,5)P2 metabolism in the brain
Cremona et al, Cell 1999
Synaptojanin 1 WT
KO
Cremona et al. 1999
Synaptojanin 1 is critical for clathrin-mediated endocytosis presynaptically.
Coupling between PI(4,5)P2 metabolism and synaptic vesicle recycling
PI(4)P PI(4,5)P2
KinasesPI(4,5)P2 PI(4)P
phosphatases