How Neurons Communicate at Synapses Jose Rizo-Rey
White gives check mate in two moves Samuel Loyd 1859
So beautiful! Samuel Loyd 1859
OUR AMAZING BRAIN http://research.vtc.vt.edu/news/2013/feb/13/brain-awareness-week-designed-highlight-advances-b/
Neurons are the key cells that make the brain so unique trauma.blog.yorku.ca arttattler.com (drawings by Santiago Ramon y Cajal)
Neurons form amazing networks neuronico.net www.the-scientist.com (drawings by Santiago Ramon y Cajal)
The brain is an extremely complex communications network Interneuronal communication occurs at synapses Xinran Liu
There are many types of neurons A common feature is their polarity biologyboom.com
The membrane potential arises from differences in the concentrations of ions inside and outside the cell mikeclaffey.com
Some ion channels can open and close depending on the membrane potential, and help to propagate electrical signals with a very fast speed a single ion channel opening and closing www.emaze.com aups.org.au
These electrical signals are known as actions potentials and are propagated by opening and closing of sodium and potassium channels faculty.washington.edu
Synaptic transmission occurs at synapses cjonesbvis518.wordpress.com
Chemical synaptic transmission synaptic vesicles presynaptic action potential terminal docking priming Ca 2+ fusion Ca 2+ synaptic cleft neurotransmitter postsynaptic receptors cell
Binding of neurotransmitters to postsynaptic receptors can cause excitatory or inhibitory postsynaptic potentials (EPSPs or IPSPs), depending of the type of synapse and the neurotransmitter released presynaptic neuron EPSP postsynaptic neuron presynaptic neuron IPSP 7e.biopsychology.com postsynaptic neuron
Different inputs are integrated at the cell body, leading to an action potential in the axon depending on the balance of the inputs www.pinterest.com
• Repetitive stimulation can lead to stronger or weaker postsynaptic potentials • This plasticity can arise from: presynaptic changes in the efficiency of neurotransmitter release and/or changes in the postsynaptic responses • Synaptic plasticity underlies many forms of information processing in the brain Shin et al. (2010) Nat. Struct. Mol. Biol. 2010 17 , 280
The knee-jerk reflex illustrates a behavior controlled by a system of distinct neurons bio1152.nicerweb.com
Synaptic vesicle fusion is key for interneuronal communication synaptic vesicles presynaptic action potential terminal docking priming Ca 2+ fusion Ca 2+ synaptic cleft neurotransmitter postsynaptic receptors cell
Llui uis Rizo
Llui uis Rizo
Cytoplasm SNAP C2B C2A NSF Rabphilin ZF Rab3A Munc13 C2B C2C Syntaxin Munc18 Rim Synaptic Vesicle MUN C2A C2A C2B PDZ Rab3A SNAP-25 C2B C2A ZF C1 Synaptotagmin Complexin Synaptobrevin Plasma Membrane Synaptic Cleft
Structures and Ca 2+ binding modes of the synaptotagmin-1 C 2 domains C 2 A C 2 B Shao et al. Science 273, 248 (1996) Ubach et al. EMBO J. 17, 3921 (1998) Shao et al. Biochemistry 37, 16106 (1998) Fernandez et al. Neuron 32, 1057 (2001)
Synaptotagmin I acts as a Ca2+ sensor in neurotransmitter release In vitro Ca2+-dependent In vivo Ca2+-dependence of phospholipid binding neurotransmitter release Fernandez-Chacon et al. Nature 410, 41 (2001)
Cytoplasm SNAP C2B C2A NSF Rabphilin ZF Rab3A Munc13 C2B C2C Syntaxin Munc18 Rim Synaptic Vesicle MUN C2A C2A C2B PDZ Rab3A SNAP-25 C2B C2A ZF C1 Synaptotagmin Complexin Synaptobrevin Plasma Membrane Synaptic Cleft
The SNARE complex N H abc -domain Synaptic vesicle synaptobrevin syntaxin SNAP25 C N Plasma membrane Sutton et al. (1998) Nature 395, 347 Fernandez et al. (1998) Cell 18, 841
Widespread, SNARE-centric model of synaptic vesicle fusion Synaptic Synaptic vesicle vesicle Syntaxin-1(open)/SNAP-25 Syntaxin-1 Synaptobrevin (closed) Synaptobrevin SNAP-25 Plasma membrane Vesicle recycling NSF/SNAPs SNARE complex
Model for how synaptotagmin cooperates with the SNAREs to induce calcium-dependent membrane fusion synaptotagmin Ca 2+ - - - - - - C 2 A C 2 B - - - -
LIPID MIXING ASSAY TO STUDY MEMBRANE FUSION IN VITRO 1.8 1.6 1.4 I538/I589 1.2 1.0 0.8 0.6 0.4 0 50 100 150 Time (mins)
Weber et al. (1998) Cell 92, 759
Efficient membrane fusion in vitro with SNAREs and Synaptotagmin -1 SNAREs + Ca 2+ + Synaptotagmin-1 SNAREs alone Tucker et al. Science 304 , 435 (2004) Chicka et al. Nat. Struct. Mol. Biol. 15 , 827 (2008) Xue et al. Nat. Struct. Mol. Biol. 15 , 1160 (2008) But without Munc18-1 or Munc13!
Total abrogation of neurotransmitter release In the absence of Munc18-1 or Munc13s Munc18-1 KO Total silence control Munc18-1 KO Verhage et al. Science 287 , 864 (2000) Munc13-1/2 KO Total silence control Munc13-1/2 DKO Varoqueaux et al. Proc. Natl. Acad. Sci. U. S. A 99 , 9037 (2002)
Model of Munc18-1 and Munc13 function synaptobrevin + + + + + + + + Munc18-1 + + SNAP-25 + + + + + + + + Munc13 MUN domain syntaxin + + + + + + closed + + + + + + + + + + + + + + + + + + + + + + + + Fernandez et al. Cell 18, 841 (1998) Dulubova et al. EMBO J. 18 , 4372 (1999) Carr et al. J. Cell Biol. 146, 333 (1999) Yamaguchi et al. Developmental Cell 2 , 295 (2002) Dulubova et al. EMBO J. 21 , 3620 (2002) Dulubova et al. PNAS 100 , 32 (2003) Dulubova et al. PNAS 104 , 2697 (2007) Deak, Xu et al., J. Cell. Biol. 184, 751 (2009) Xu et al., Biochemistry 49, 1568 (2010) Ma et al., Nat. Struct. Molec. Biol. 18, 542 (2011)
Reconstitution of membrane fusion with Syntaxin-1/Munc18-1 liposomes + Synaptobrevin liposomes + Munc13-1, SNAP-25 and Synaptotagmin-1 Synaptobrevin D A Syntaxin-1 Munc18-1 Fluorescence (% of max) 30 +SNAP-25+synaptotagmin+ Munc13-1 20 10 +Synaptotagmin+Munc13-1 +SNAP-25+ 0 Synaptotagmin +SNAP-25+Munc13-1 0 500 1000 1500 2000 2500 Time (s) Ma et al. Science 339, 421 (2013)
Efficient fusion with Syntaxin-1/SNAP-25 liposomes + Synaptobrevin liposomes + Synaptotagmin-1 Synaptobrevin D + A SNAP-25 Syntaxin-1 40 Fluorescence (% of max) 30 +synaptotagmin 20 10 0 0 500 1000 1500 2000 2500 Time (s) Ma et al. Science 339, 421 (2013)
Fusion with Syntaxin-1/SNAP-25 liposomes + Synaptobrevin liposomes + Synaptotagmin-1 is inhibited by NSF, a -SNAP Synaptobrevin D + A SNAP-25 Syntaxin-1 40 Fluorescence (% of max) 30 +synaptotagmin 20 10 +synaptotagmin+NSF/ a SNAP+ATP 0 0 500 1000 1500 2000 2500 Time (s) Ma et al. Science 339, 421 (2013)
Reconstitution of synaptic vesicle fusion with Syntaxin-1/SNAP-25 liposomes + Synaptobrevin liposomes + Munc18-1, Munc13-1, NSF, a -SNAP and Synaptotagmin-1!!!!! Synaptobrevin D + A SNAP-25 Syntaxin-1 +synaptotagmin+NSF/ a SNAP+ATP 40 +M18+Munc13-1 Fluorescence (% of max) 30 +synaptotagmin 20 WE GOT IT! +synaptotagmin+NSF/ a SNAP 10 +ATP+Munc13-1 +synaptotagmin+NSF/ a SNAP+ATP 0 0 500 1000 1500 2000 2500 Time (s) Ma et al. Science 339, 421 (2013)
Highly efficient calcium-dependent membrane fusion supported by the SNARES, Synaptotagmin-1, Mun18-1, Munc13-1, Synaptotagmin-1 and NSF- a -SNAP Synaptobrevin D synaptotagmin A SNAP-25 Syntaxin-1 Lipid mixing T+VSyt1 +NSF/ a SNAP Content mixing T+VSyt1 +NSF/ a SNAP 30 Ca 2+ Ca 2+ 100 Fluorescence (% of max) Fluorescence (% of max) +Munc13-1+Munc18-1 +Munc13-1+Munc18-1 80 20 60 40 10 +Munc13-1 +Munc18-1 20 +Munc13-1 0 +Munc18-1 0 T+VSyt1 T+VSyt1 0 500 1000 1500 2000 2500 0 500 1000 1500 2000 2500 Time (s) Time (s) Xiaoxia Liu, Alpay Seven
Model of synaptic vesicle fusion integrating the functions of SNAREs, Munc18-1, Munc13s, NSF/SNAPs and synaptotagmin-1 Synaptotagmin-1 Synaptic vesicle Syntaxin-1(open)/SNAP-25 NSF/SNAPs Synaptobrevin + Munc18-1 Munc18-1 SNAP-25 Syntaxin-1 (closed) Munc18-1 Plasma membrane Munc13 Ca 2+ Munc13 Ma et al. Science 339, 421 (2013)
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