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dc.contributor.advisorSüdhof, Thomas C.en
dc.creatorPang, Zhipingen
dc.date.accessioned2010-07-12T18:42:42Zen
dc.date.available2010-07-12T18:42:42Zen
dc.date.issued2007-08-08en
dc.identifier.other664113598en
dc.identifier.urihttp://hdl.handle.net/2152.5/643en
dc.description.abstractNeurotransmitter release is triggered by the action potential induced influx of Ca 2+ into nerve terminals. One of the central questions in neuroscience is how Ca 2+ promotes synaptic vesicles from rest to fusion leading to release of neurotransmitters. In this thesis, I first addressed if synaptogmin-1/SNARE binding is important for synaptic vesicle release. Using two knock-in mouse lines each with single amino-acid substitution, namely D232N and D238N in synaptotagmin-1, combined with electrophysiology, I found evoked release in D232N mutant neuronal cultures is significantly increased, whereas in D238N cultures release is slightly but significantly decreased. Ca 2+ titration curves indicated the apparent Ca 2+-affinity for vesicle release significantly increased in D232N synapses. These data are consistent with biochemical studies that showed that the D232N substitution in synaptotagmin-1 increases Ca 2+-dependent SNARE bindings but leaves phospholipid binding unchanged, whereas the D238N mutant slightly decreased phospholipid binding but leaves SNARE binding insignificantly changed. Second, I addressed if synaptotamgin-2 is another Ca 2+-sensor for synaptic vesicle release. I and my colleagues used two mouse lines: one contains a single amino acid mutation in synaptotagmin-2 (I377N) and one has synaptotagmin-2 ablated from the genome. By using a combination of biophysical, biochemical and functional techniques, we determined that synaptotagmin-2 is a fast synchronous Ca 2+-sensor. Third, in collaboration with Jianyuan Sun, we explored the biophysical properties of the slow Ca 2+-sensor in the Calyx of Held. Using Ca 2+-uncaging combined with electrophysiology, we mapped increasing Ca 2+ concentrations in relation to neurotransmitter release and built a comprehensive mathematical model for the Ca 2+ control of synaptic vesicle fusion. We found compelling evidence for the existence of two Ca 2+- sensors: one (synaptotagmin-2 in the Calyx of Held) is responsible for fast synchronous release, and the other one is responsible for slow delayed synaptic release. Surprisingly, we found the two Ca 2+-sensors have similar apparent Ca 2+ affinities. This study showed clearly that synaptotagmin-2 is a fast Ca 2+-sensor, and gave us a prediction that narrows down the potential candidate for the slow Ca 2+-sensor.en
dc.format.mediumElectronicen
dc.format.mimetypeapplication/pdfen
dc.language.isoenen
dc.subjectCalciumen
dc.subjectSynapsesen
dc.subjectSynaptic Transmissionen
dc.titleCalcium Triggered Synaptic Vesicle Exocytosisen
dc.type.materialTexten
dc.type.genredissertationen
dc.format.digitalOriginborn digitalen
thesis.degree.grantorGraduate School of Biomedical Sciencesen
thesis.degree.departmenten
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelPh.D.en
thesis.degree.disciplineNeuroscienceen
thesis.date.available2007-08-08en


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