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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS042599-08
Application #
8318760
Study Section
Special Emphasis Panel (ZRG1-MDCN-P (02))
Program Officer
Talley, Edmund M
Project Start
2001-12-01
Project End
2014-08-31
Budget Start
2012-09-01
Budget End
2014-08-31
Support Year
8
Fiscal Year
2012
Total Cost
$332,281
Indirect Cost
$117,906
Name
Emory University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
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
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
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
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
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
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
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 IIα. Mol Biol Cell 24:2269-84
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
Muthusamy, Nagendran; Faundez, Victor; Bergson, Clare (2012) Calcyon, a mammalian specific NEEP21 family member, interacts with adaptor protein complex 3 (AP-3) and regulates targeting of AP-3 cargoes. J Neurochem 123:60-72
Gokhale, Avanti; Perez-Cornejo, Patricia; Duran, Charity et al. (2012) A comprehensive strategy to identify stoichiometric membrane protein interactomes. Cell Logist 2:189-196

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