Acetylcholine, a neurotransmitter implicated in memory and Alzheimer's disease, binds to and activates ligand-gated ion channels, G protein Gq-coupled receptors, and G protein Gi-coupled receptors. Hence, a single neurotransmitter can access a multitude of signaling pathways in neurons. Because activation of each of these pathways could result in a different biological response, neurons must functionally segregate these different signaling pathways. The molecular mechanism by which neurons isolate signaling pathways remains an enigma and is one of the most important questions facing Neuroscientists today. The study of G protein-gated inwardly rectifying K+ channels (GIRK) is an excellent system for identifying the molecular determinants of receptor specificity. GIRK channels are opened by the G protein G beta gamma subunits but show little discrimination among the different combinations of G beta and Ggamma, subunits in vitro. Because specific combinations of G beta gamma subunits do not selectively open GIRK channels, any G protein-coupled neurotransmitter receptor could theoretically open GIRK channels. However, neurons ensure that acetylcholine will open GIRK channels following stimulation of G protein Gi-coupled but not Gq-coupled cholinergic receptors. This type of receptor specificity is common among many different types of neurotransmitter signaling pathways. In this proposal, the hypothesis that a protein-protein interaction between the GIRK channel and a subset of G proteins determines the specificity of receptor coupling will be examined. The hypothesis will be tested using biochemistry for examining direct protein-protein binding interactions, electrophysiology for assessing the physiology of GIRK channels, laser confocal microscopy for visualizing the localization of GIRK channels and neurotransmitter receptors, and finally fluorescence spectroscopy for measuring protein-protein interactions in living cells. In addition, we will be using cultures of hippocampal neurons to identify the domains in GIRK channels that are important for targeting to the dendritic shafts. Results from this grant will significantly advance our understanding of the principles governing coupling of G protein-coupled receptors to GIRK channels, and may contribute to specific pharmaceutical strategies for treating humans with diseases that are caused by abnormal neuronal membrane excitability.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
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Stewart, Randall R
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Salk Institute for Biological Studies
La Jolla
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Balana, Bartosz; Maslennikov, Innokentiy; Kwiatkowski, Witek et al. (2011) Mechanism underlying selective regulation of G protein-gated inwardly rectifying potassium channels by the psychostimulant-sensitive sorting nexin 27. Proc Natl Acad Sci U S A 108:5831-6
Nassirpour, Rounak; Bahima, Laia; Lalive, Arnaud L et al. (2010) Morphine- and CaMKII-dependent enhancement of GIRK channel signaling in hippocampal neurons. J Neurosci 30:13419-30
L├╝scher, Christian; Slesinger, Paul A (2010) Emerging roles for G protein-gated inwardly rectifying potassium (GIRK) channels in health and disease. Nat Rev Neurosci 11:301-15
Boyer, Stephanie B; Clancy, Sinead M; Terunuma, Miho et al. (2009) Direct interaction of GABAB receptors with M2 muscarinic receptors enhances muscarinic signaling. J Neurosci 29:15796-809
Lunn, Marie-Louise; Nassirpour, Rounak; Arrabit, Christine et al. (2007) A unique sorting nexin regulates trafficking of potassium channels via a PDZ domain interaction. Nat Neurosci 10:1249-59
Kurata, Harley T; Cheng, Wayland W; Arrabit, Christine et al. (2007) The role of the cytoplasmic pore in inward rectification of Kir2.1 channels. J Gen Physiol 130:145-55
Clancy, Sinead M; Boyer, Stephanie B; Slesinger, Paul A (2007) Coregulation of natively expressed pertussis toxin-sensitive muscarinic receptors with G-protein-activated potassium channels. J Neurosci 27:6388-99
Fowler, Catherine E; Aryal, Prafulla; Suen, Ka Fai et al. (2007) Evidence for association of GABA(B) receptors with Kir3 channels and regulators of G protein signalling (RGS4) proteins. J Physiol 580:51-65
Clancy, Sinead M; Fowler, Catherine E; Finley, Melissa et al. (2005) Pertussis-toxin-sensitive Galpha subunits selectively bind to C-terminal domain of neuronal GIRK channels: evidence for a heterotrimeric G-protein-channel complex. Mol Cell Neurosci 28:375-89
Finley, Melissa; Arrabit, Christine; Fowler, Catherine et al. (2004) betaL-betaM loop in the C-terminal domain of G protein-activated inwardly rectifying K(+) channels is important for G(betagamma) subunit activation. J Physiol 555:643-57