Our long-term objectives are to determine the sub-cellular processes, and their molecular substrates, which control the efficiency of synaptic transmission in the central nervous system (CMS). Our approach is to use methods that allow us to isolate and study distinct steps in the cycling of synaptic vesicles in the presynaptic terminal. Our previous work demonstrates the usefulness and applicability of a number of different optical probes, including the fluorescent tracer FM 1-43 and the more recently-developed pH-based sensor of synaptic activity, svnapto-DHIuorin. for studying synaptic vesicle recycling in single presynaptic terminals in dissociated neuronal cell cultures. Here we propose to examine several aspects of the coupling of exocytosis and endocytosis and how it is controlled using biophysical, molecular and genetic means. Our working hypothesis is that the proper functioning of the complete synaptic vesicle cycle is critical to coordinating information flow in the brain. Because of its cyclic nature, modulation at any point in the synaptic vesicle cycle could prove important in controlling synaptic efficacy. Similarly, dysfunction of any of the steps in the vesicle cycle, such as might arise in specific mutations in diseased states, could lead to impairment of synaptic transmission. One of the critical steps in the synaptic vesicle cycle is the endocytic retrieval of synaptic vesicle membrane and proteins for future reuse. We propose 4 specific aims to examine how endocvtosis is controlled and how different molecules participate in endocvtosis for different types of physiological stimuli. 1) Examine the role of dynamin-1 in synaptic vesicle endocytosis at CMS nerve terminals 2) Examine the role of synaptojanin-1 in synaptic vesicle endocytosis at CMS nerve terminals 3) Examine the role of clathrin in in synaptic vesicle endocytosis at CMSnerve terminals 4) Examine the role of different endocytic adaptors as well as the importance of sorting motifs and interactions with synaptophysin in controlling synaptic vesicle membrane protein recapture and endocytosis.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Talley, Edmund M
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Weill Medical College of Cornell University
Schools of Medicine
New York
United States
Zip Code
Ashrafi, Ghazaleh; Wu, Zhuhao; Farrell, Ryan J et al. (2017) GLUT4 Mobilization Supports Energetic Demands of Active Synapses. Neuron 93:606-615.e3
Ashrafi, Ghazaleh; Ryan, Timothy A (2017) Glucose metabolism in nerve terminals. Curr Opin Neurobiol 45:156-161
Cao, Mian; Wu, Yumei; Ashrafi, Ghazaleh et al. (2017) Parkinson Sac Domain Mutation in Synaptojanin 1 Impairs Clathrin Uncoating at Synapses and Triggers Dystrophic Changes in Dopaminergic Axons. Neuron 93:882-896.e5
de Juan-Sanz, Jaime; Holt, Graham T; Schreiter, Eric R et al. (2017) Axonal Endoplasmic Reticulum Ca2+ Content Controls Release Probability in CNS Nerve Terminals. Neuron 93:867-881.e6
Pan, Ping-Yue; Marrs, Julia; Ryan, Timothy A (2015) Vesicular glutamate transporter 1 orchestrates recruitment of other synaptic vesicle cargo proteins during synaptic vesicle recycling. J Biol Chem 290:22593-601
Wragg, Rachel T; Gouzer, GĂ©raldine; Bai, Jihong et al. (2015) Synaptic activity regulates the abundance and binding of complexin. Biophys J 108:1318-29
Rangaraju, Vidhya; Calloway, Nathaniel; Ryan, Timothy A (2014) Activity-driven local ATP synthesis is required for synaptic function. Cell 156:825-35
Armbruster, Moritz; Messa, Mirko; Ferguson, Shawn M et al. (2013) Dynamin phosphorylation controls optimization of endocytosis for brief action potential bursts. Elife 2:e00845
Kim, Sung Hyun; Ryan, Timothy A (2013) Balance of calcineurin A? and CDK5 activities sets release probability at nerve terminals. J Neurosci 33:8937-50
Ariel, Pablo; Ryan, Timothy A (2012) New insights into molecular players involved in neurotransmitter release. Physiology (Bethesda) 27:15-24

Showing the most recent 10 out of 21 publications