A defining feature of presynaptic terminals is the presence of synaptic vesicles (SVs), secretory organelles that store and secrete neurotransmitters. SVs functions are specified by the organelle membrane protein composition. Thus, mechanisms controlling SV formation and composition are pivotal for synapse function. In this proposal we focus on the vesicle biogenesis pathway controlled by the adaptor complex AP-3, a coat complex that sorts membrane proteins from early endosomes to SVs. SV protein composition is regulated by two isoforms of the adaptor complex AP-3, neuronal and ubiquitous, the later thought to participate exclusively in lysosome biogenesis. Genetic defects in the neuronal AP-3 isoform hinder targeting of SV membrane proteins. Surprisingly, null mouse mutants in a lysosomal sorting pathway, the ubiquitous AP-3 route, trigger accruement of SV-specific proteins in SVs. These unexpected results lead us to propose the novel concept that SV and lysosomal sorting mechanisms present on the same endosome compete for membrane proteins to be delivered into two alternative routes, SVs or lysosomes. This concept departs from the traditional view of lysosomes, which are viewed as terminal organelles involved in the disposal of normal and pathological cellular components. Furthermore, our model provides a novel way to understand the contribution of lysosome targeting mechanisms to familial and sporadic forms of neurodegeneration that affect children and adult individuals. Our central hypothesis is that: AP-3-isoform-specific mechanisms target SV membrane proteins from a common endosomal compartment to two competing pathways: either to a SV biogenesis route or to a late endosome-lysosomal path. In this proposal, we will focus on four predictions derived from our hypothesis. These predictions will be systematically explored using a combination of mouse deficient models that affect SV and endo- lysosomal targeting, high-resolution immuno-electron and in vivo imaging microscopy, as well as the molecular analysis of isolated SVs and endosomes. Information gained in this proposal will illuminate our understanding of how late endosomes-lysosome sorting processes affect synapses under physiological and pathological conditions.

Public Health Relevance

We propose a model that will contribute knowledge to understand how lysosomes and synapses interface and contribute to neurodegenerative and psychiatric disorders.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-MDCN-P (02))
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Talley, Edmund M
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Emory University
Anatomy/Cell Biology
Schools of Medicine
United States
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Hartwig, Cortnie; Monis, William J; Chen, Xun et al. (2017) Neurodevelopmental disease mechanisms, primary cilia, and endosomes converge on the BLOC-1 and BORC complexes. Dev Neurobiol :
Gokhale, Avanti; Ryder, Pearl V; Zlatic, Stephanie A et al. (2016) Identification of the Interactome of a Palmitoylated Membrane Protein, Phosphatidylinositol 4-Kinase Type II Alpha. Methods Mol Biol 1376:35-42
Larimore, Jennifer; Zlatic, Stephanie A; Gokhale, Avanti et al. (2014) Mutations in the BLOC-1 subunits dysbindin and muted generate divergent and dosage-dependent phenotypes. J Biol Chem 289:14291-300
Evstratova, Alesya; Chamberland, Simon; Faundez, Victor et al. (2014) Vesicles derived via AP-3-dependent recycling contribute to asynchronous release and influence information transfer. Nat Commun 5:5530
Tornieri, Karine; Zlatic, Stephanie A; Mullin, Ariana P et al. (2013) Vps33b pathogenic mutations preferentially affect VIPAS39/SPE-39-positive endosomes. Hum Mol Genet 22:5215-28
Ryder, P V; Vistein, R; Gokhale, A et al. (2013) The WASH complex, an endosomal Arp2/3 activator, interacts with the Hermansky-Pudlak syndrome complex BLOC-1 and its cargo phosphatidylinositol-4-kinase type II?. Mol Biol Cell 24:2269-84
Mullin, A P; Gokhale, A; Moreno-De-Luca, A et al. (2013) Neurodevelopmental disorders: mechanisms and boundary definitions from genomes, interactomes and proteomes. Transl Psychiatry 3:e329
Zlatic, Stephanie A; Grossniklaus, Emily J; Ryder, Pearl V et al. (2013) Chemical-genetic disruption of clathrin function spares adaptor complex 3-dependent endosome vesicle biogenesis. Mol Biol Cell 24:2378-88
Simionescu-Bankston, Adriana; Leoni, Giovanna; Wang, Yanru et al. (2013) The N-BAR domain protein, Bin3, regulates Rac1- and Cdc42-dependent processes in myogenesis. Dev Biol 382:160-71
Perez-Cornejo, Patricia; Gokhale, Avanti; Duran, Charity et al. (2012) Anoctamin 1 (Tmem16A) Ca2+-activated chloride channel stoichiometrically interacts with an ezrin-radixin-moesin network. Proc Natl Acad Sci U S A 109:10376-81

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