Persistent Link:
http://hdl.handle.net/10150/279946
Title:
Genetic analysis of endocytosis at the Drosophila synapse
Author:
Narayanan, Radhakrishnan
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Endocytosis plays an essential role in maintaining a pool of synaptic vesicles for sustained neurotransmitter release. Synaptic vesicles are internalized and fuse with endosomes, and are subsequently reassembled to be ready for another round of exocytosis. Here I describe in two distinct studies the function of endosomes at synapses and regulation of dynamin, a protein essential for endocytosis, using the Drosophila synapse as a model. To study the function of endosomes at synapses I analyzed the localization and function of two Drosophila endosomal proteins, Hook and Deep orange (Dor), at the larval neuromuscular junction. I present here the first genetic evidence of a role for endocytic trafficking in plasticity of the synapse. I also found that mutations in hook and dor affect the number of varicosities at the nerve terminal without affecting synaptic vesicle recycling, indicating that Hook and Dor proteins play a role in later stages of endocytosis at the synapse. Dynamin is a GTPase that is essential for internalization of synaptic vesicles from the plasma membrane. Flies carrying shi ts mutations have a conditional defect in dynamin function. Molecules that regulate GTP loading (guanine-nucleotide exchange factors-GEFs) and GTPase activity (GTPase activating proteins-GAPs) of dynamin are unknown. Here I describe the identification of such molecules/domains by analyses of enhancer and suppressor mutations identified in previously conducted genetic screens. I show here that the enzymatic activity of Nucleoside diphosphate kinase (NDP Kinase), a source of GTP encoded by the Drosophila abnormal wing discs (awd) or human nm23 tumor suppressor genes, is essential for dynamin function at synapses. Dynamin is also regulated by an intramolecular GTPase effector domain (GED) and I have identified separate mutations in shi, which map to the GED, that suppress endocytic defects in shits2. Overall, these data indicate a model in which the stability of dynamin: GTP is opposingly regulated by an unusual GEF activity of NDP kinase and a GAP activity in dynamin; in addition these findings indicate the possibility of an intriguing therapy for nm23 tumor progression.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Molecular.; Biology, Neuroscience.; Biology, Cell.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Molecular and Cellular Biology
Degree Grantor:
University of Arizona
Advisor:
Ramaswami, Mani

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleGenetic analysis of endocytosis at the Drosophila synapseen_US
dc.creatorNarayanan, Radhakrishnanen_US
dc.contributor.authorNarayanan, Radhakrishnanen_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEndocytosis plays an essential role in maintaining a pool of synaptic vesicles for sustained neurotransmitter release. Synaptic vesicles are internalized and fuse with endosomes, and are subsequently reassembled to be ready for another round of exocytosis. Here I describe in two distinct studies the function of endosomes at synapses and regulation of dynamin, a protein essential for endocytosis, using the Drosophila synapse as a model. To study the function of endosomes at synapses I analyzed the localization and function of two Drosophila endosomal proteins, Hook and Deep orange (Dor), at the larval neuromuscular junction. I present here the first genetic evidence of a role for endocytic trafficking in plasticity of the synapse. I also found that mutations in hook and dor affect the number of varicosities at the nerve terminal without affecting synaptic vesicle recycling, indicating that Hook and Dor proteins play a role in later stages of endocytosis at the synapse. Dynamin is a GTPase that is essential for internalization of synaptic vesicles from the plasma membrane. Flies carrying shi ts mutations have a conditional defect in dynamin function. Molecules that regulate GTP loading (guanine-nucleotide exchange factors-GEFs) and GTPase activity (GTPase activating proteins-GAPs) of dynamin are unknown. Here I describe the identification of such molecules/domains by analyses of enhancer and suppressor mutations identified in previously conducted genetic screens. I show here that the enzymatic activity of Nucleoside diphosphate kinase (NDP Kinase), a source of GTP encoded by the Drosophila abnormal wing discs (awd) or human nm23 tumor suppressor genes, is essential for dynamin function at synapses. Dynamin is also regulated by an intramolecular GTPase effector domain (GED) and I have identified separate mutations in shi, which map to the GED, that suppress endocytic defects in shits2. Overall, these data indicate a model in which the stability of dynamin: GTP is opposingly regulated by an unusual GEF activity of NDP kinase and a GAP activity in dynamin; in addition these findings indicate the possibility of an intriguing therapy for nm23 tumor progression.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Molecular.en_US
dc.subjectBiology, Neuroscience.en_US
dc.subjectBiology, Cell.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineMolecular and Cellular Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRamaswami, Manien_US
dc.identifier.proquest3050301en_US
dc.identifier.bibrecord.b4272384xen_US
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