Release of chemical transmitters by regulated exocytosis underlies many forms of intercellular communication, including hormone release and synaptic transmission. G protein-coupled receptors (GPCRs) orchestrate complex regulation of exocytosis, and in particular inhibit transmitter release from neurosecretory cells. Inhibitory GPCRs can be auto- or hetero-receptors, are typically Gi/o coupled, and work by release of G protein beta-gamma subunits (Gbeta-gamma). The most intensively studied mechanism of inhibition involves modulation of voltage-gated Ca2+ channels (Ca-channels), but direct effects on the exocytotic apparatus have also been reported. Our preliminary data show that Gbeta-gamma binds to SNAP25 and syntaxin-1A, suggesting that Ca-channels and SNAREs might be targeted in parallel by Gbeta-gamma to inhibit exocytosis. The central goal of this proposal is to dissect the molecular basis by which Gbeta-gamma controls exocytotic transmitter release in neurosecretory cells. To enable the precise biophysical analyses required to address this goal, we will use adrenal chromaffin cells, a neurosecretory model that provides significant experimental advantages. Furthermore, catecholamines released from chromaffin cells play important physiological roles in the coordinated response to stress or danger. We will combine carbon fiber amperometry, patch clamp electrophysiology, and flash photolysis of caged compounds, along with novel molecular tools (mutant Gbeta-gamma subunits and inhibitory peptides) to dissect the roles of Ca-channels and SNAREs in Gbeta-gamma -mediated regulation of exocytosis.
In aim #1 we will test the hypothesis that Gbeta-gamma acts in parallel at Ca-channels and other downstream targets to inhibit transmitter.
In aim #2 we will characterize the interaction of Gbeta-gamma with the exocytotic machinery and test the hypothesis that Gbeta-gamma inhibits exocytosis by competing with synaptotagmin-l for binding to SNAP25.
In aim #3 we will use mutational and peptide mapping to characterize the Gbeta-gamma - SNAP25 interaction and generate novel molecular tools to dissect its role in the regulation of chromaffin cell exocytosis. To summarize, our investigations will significantly advance knowledge of the molecular mechanisms that control neurotransmitter and hormone secretion, and provide insight into the pathological basis of diseases related to secretion and neuromodulation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS052446-04
Application #
7651094
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Stewart, Randall R
Project Start
2006-08-01
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
4
Fiscal Year
2009
Total Cost
$335,359
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Zurawski, Zack; Page, Brian; Chicka, Michael C et al. (2017) G?? directly modulates vesicle fusion by competing with synaptotagmin for binding to neuronal SNARE proteins embedded in membranes. J Biol Chem 292:12165-12177
Zhu, Lei; McDavid, Sarah; Currie, Kevin P M (2015) ""Slow"" Voltage-Dependent Inactivation of CaV2.2 Calcium Channels Is Modulated by the PKC Activator Phorbol 12-Myristate 13-Acetate (PMA). PLoS One 10:e0134117
McDavid, Sarah; Bauer, Mary Beth; Brindley, Rebecca L et al. (2014) Butanol isomers exert distinct effects on voltage-gated calcium channel currents and thus catecholamine secretion in adrenal chromaffin cells. PLoS One 9:e109203
Zamponi, Gerald W; Currie, Kevin P M (2013) Regulation of Ca(V)2 calcium channels by G protein coupled receptors. Biochim Biophys Acta 1828:1629-43
Ges, Igor A; Brindley, Rebecca L; Currie, Kevin P M et al. (2013) A microfluidic platform for chemical stimulation and real time analysis of catecholamine secretion from neuroendocrine cells. Lab Chip 13:4663-73
Todd, Robert D; McDavid, Sarah M; Brindley, Rebecca L et al. (2012) Gabapentin inhibits catecholamine release from adrenal chromaffin cells. Anesthesiology 116:1013-24
Ges, Igor A; Currie, Kevin P M; Baudenbacher, Franz (2012) Electrochemical detection of catecholamine release using planar iridium oxide electrodes in nanoliter microfluidic cell culture volumes. Biosens Bioelectron 34:30-6
Jewell, Mark L; Breyer, Richard M; Currie, Kevin P M (2011) Regulation of calcium channels and exocytosis in mouse adrenal chromaffin cells by prostaglandin EP3 receptors. Mol Pharmacol 79:987-96
Currie, Kevin P M (2010) Inhibition of Ca2+ channels and adrenal catecholamine release by G protein coupled receptors. Cell Mol Neurobiol 30:1201-8
Currie, Kevin P M (2010) G protein modulation of CaV2 voltage-gated calcium channels. Channels (Austin) 4:497-509

Showing the most recent 10 out of 13 publications