Timely initiation and cessation of intercellular communication via heterotrimeric G protein-coupled receptors (GPCRs) is crucial for normal functioning of brain and sensory neurons. Aberration of this process can lead to pathophysiological deficits in peripheral or central nervous system activity;conversely, stimulation, prolongation, or antagonism of GPCR signaling underlies the actions of many psychoactive and neurotropic agents. In 1996, a new class of proteins was discovered that directly modulate the timing of GPCR signaling - the """"""""regulators of G-protein signaling"""""""" (RGS) proteins. The overall goal of the Siderovski laboratory is to identify specific roles for RGS proteins in (patho)physiological process and thus establish select members of the RGSfamily as viable drug discovery targets. RGS12 is specifically involved in determining desensitization from GABA(B) receptor-mediated inhibition of presynaptic calcium current in dorsal root ganglia. Our long-term objective is to define the molecular determinants that constitute the desensitization function of RGS12. Beyond the hallmark GTPase-accelerating activity specified by the RGS12 RGS domain, we have now identified phospholipid- and phosphotyrosine-binding activity within RGS12, as well as its ability to interact with multiple components of the mitogen-activated protein kinase (MAPK) cascade. This proposal therefore describes biochemical/biophysical and cell-biological analyses of RGS12-mediated protein/protein and protein/lipid interactions, coupled with celullar studies of agonist-promoted MAPK signal transduction and electrophysiological assessment of neurotransmitter modulation of Cav2.2 channel activity in the presence of selective RGS12 mutants. Results from this work will help define the specific roles RGS12 partakes in signal transduction and ion channel modulation, as well as illuminate the potential for RGS12 as a drug discovery target for novel therapies for neuropathic pain and spasticity. Many drugs act by binding a particular protein receptor on the cell's surface: a G-protein coupled receptor. Our group discovered a new protein family - the RGS proteins - that interfere with these receptors. We wish to study one RGS protein, RGS12, that interferes with the actions of the neurotransmitter GABA in neurons that control pain processing. This work should lead to the discovery of new pain-controlling drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM062338-09
Application #
7569387
Study Section
Molecular Neuropharmacology and Signaling Study Section (MNPS)
Program Officer
Dunsmore, Sarah
Project Start
2001-02-01
Project End
2011-01-31
Budget Start
2009-02-01
Budget End
2011-01-31
Support Year
9
Fiscal Year
2009
Total Cost
$258,751
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Pharmacology
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Kimple, Adam J; Bosch, Dustin E; Giguere, Patrick M et al. (2011) Regulators of G-protein signaling and their Gýý substrates: promises and challenges in their use as drug discovery targets. Pharmacol Rev 63:728-49
Laroche, Genevieve; Giguere, Patrick M; Roth, Bryan L et al. (2010) RNA interference screen for RGS protein specificity at muscarinic and protease-activated receptors reveals bidirectional modulation of signaling. Am J Physiol Cell Physiol 299:C654-64
Johnston, Christopher A; Siderovski, David P (2007) Receptor-mediated activation of heterotrimeric G-proteins: current structural insights. Mol Pharmacol 72:219-30
Winter-Vann, Ann M; Johnson, Gary L (2007) Integrated activation of MAP3Ks balances cell fate in response to stress. J Cell Biochem 102:848-58
Willard, Melinda D; Willard, Francis S; Li, Xiaoyan et al. (2007) Selective role for RGS12 as a Ras/Raf/MEK scaffold in nerve growth factor-mediated differentiation. EMBO J 26:2029-40
Willard, Francis S; Low, Aaron B; McCudden, Christopher R et al. (2007) Differential G-alpha interaction capacities of the GoLoco motifs in Rap GTPase activating proteins. Cell Signal 19:428-38
Willard, Francis S; McCudden, Christopher R; Siderovski, David P (2006) G-protein alpha subunit interaction and guanine nucleotide dissociation inhibitor activity of the dual GoLoco motif protein PCP-2 (Purkinje cell protein-2). Cell Signal 18:1226-34
Sambi, Balwinder S; Hains, Melinda D; Waters, Catherine M et al. (2006) The effect of RGS12 on PDGFbeta receptor signalling to p42/p44 mitogen activated protein kinase in mammalian cells. Cell Signal 18:971-81
Afshar, Katayoun; Willard, Francis S; Colombo, Kelly et al. (2005) Cortical localization of the Galpha protein GPA-16 requires RIC-8 function during C. elegans asymmetric cell division. Development 132:4449-59
Johnston, Christopher A; Willard, Francis S; Jezyk, Mark R et al. (2005) Structure of Galpha(i1) bound to a GDP-selective peptide provides insight into guanine nucleotide exchange. Structure 13:1069-80

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