My long-term objective is to discover new drugs for treating addiction to drugs of abuse and alcohol. Currently, there are few FDA approved drugs for treating these diseases and more are greatly needed. Many of the neurotransmitters in the drug-reward pathway exert their effects by activating G protein-coupled receptors, which, in turn, communicate with specific G proteins and affect down-stream signaling pathways. One of the down-stream targets is the G protein-gated inwardly rectifying potassium (GIRK) channel, which we study in my laboratory. By controlling the membrane excitability of neurons, GIRK channels provide a fundamental source of neuromodulatory inhibition in the brain. My laboratory has been addressing fundamental questions concerning the function of GIRK channels in the brain, taking a broad approach of combining structural biology, biochemistry, electrophysiology and behavior. We have contributed significant work on the mechanism underlying G protein-regulation and gating of GIRK channels, provided evidence for the assembly of GIRK channels in macromolecular signaling complexes, and identified novel proteins that regulate GIRK channels. More recently, we have elucidated the subcellular mechanisms underlying the neuroplastic changes in GIRK channel signaling with drugs of abuse and alcohol.
Areas of Research
Molecular studies of GIRK channels in Alcoholism
The alcoholic beverages that we consume contain the alcohol ethanol. Ethanol produces a wide range of pharmacological effects on the nervous system, ranging from anxiolytic to intoxication. For some, however, alcohol consumptions leads to alcohol dependence, or alcohol use disorders. Ethanol produces complex effects on the body, primarily through its interactions with the central nervous system. The molecular mechanism by which ethanol alters neuronal circuits in the brain and causes alcohol use disorders is poorly understood. A major challenge in the field is determining how ethanol, which has a chemical structure of only two carbons and an hydroxyl, elicits alcohol-mediated behaviors and leads to abuse and dependence.
Ethanol directly alters the function of a number of different brain proteins, including GIRK channels. We are currently investigating the structural mechanism underlying alcohol-dependent activation of GIRK channels and the role of these channels in alcohol-related behaviors. We are taking an innovative approach of using structural biology to guide screening and selection of novel therapeutics, and validating drug effects with ex vivo and in vivo systems. Defining the physical features of the GIRK alcohol pocket for ethanol will reveal how binding of ethanol to a channel leads to changes in channel activity and affects brain function.
Role for GIRK channels in addiction
Psychostimulants, e.g., methamphetamine and cocaine, are highly addictive, accessible and abused by >1 million people. Recent work from our laboratory has established that drug exposure reduces slow inhibition, mediated by GABAB receptors that couple to GIRK channels. For example, five daily injections of a psychostimulant reduces the size of the GABAB receptor-activated GIRK current in ventral tegmental area (VTA) dopamine (DA) neurons of the reward pathway. These changes alter the excitability of DA neurons and contribute to circuit level changes in DA signaling involved in addiction.
Recently, we have described two different pathways for drug-dependent plasticity in the VTA. In GABA neurons, psychostimulant-dependent depression of GABAB-GIRK currents involves de-phosphorylation of the GABAB R2 receptor via the protein phosphatase PP2a. In DA neurons, psychostimulant-dependent depression of GABAB-GIRK currents involves the GIRK3 subunit and an endosomal trafficking protein SNX27. We are currently examining the role of GIRK channels and associated proteins in the psychostimulant-dependent modulation of slow inhibition and its impact in mouse models of addiction. To develop new therapeutics for treating addiction, it is essential to dissect out the components of drug-dependent plasticity in the brain and discover novel protein targets in the reward pathway.
Real-time optical measurements of neurotransmitter release in vivo
In collaboration with Professor Kleinfeld at UCSD, we have developed an innovative neurotechnique for optically measuring release of neurotransmitters in cell-specific and circuit-specific processes in the brain. Our technique is based on a new technology of cell-based neurotransmitter fluorescent engineered reporters, referred to as CNiFERs. A CNiFER is a clonal HEK293 cell that is engineered to express a specific G-protein coupled receptor and couples to a FRET-based Ca2+ indicator. Release of transmitter stimulates the native GPCR and induces an increase in FRET in the CNiFER. CNiFERs can detect nanoMolar concentrations of transmitter, have a temporal resolution of seconds, and a spatial resolution of < 100 μm. CNiFERs are implanted in the brain, where they produce minimal inflammation, and can be monitored over one week or more for in vivo longitudinal studies. We have created CNiFERs for detecting acetylcholine (M1-CNiFER), dopamine (D2-CNiFER) and norepinephrine (α1a-CNiFER) and have measured volume transmission of DA, norepinephrine, and acetylcholine in vivo during learning.
We are currently constructing CNiFERs for detecting neuropeptides in vivo. Neuropeptides are genetically encoded molecules that are widely expressed in the brain. Neuropeptides diffuse over long distances and signal through G protein coupled neuropeptide receptors. It is currently not possible to monitor release of peptides in real time. Neuropeptide CNiFERs should make it possible to measure in peptide release in real-time in awake animals as they perform complex behaviors, significantly advancing studies on the function of neuropeptides in regulating neural circuits in the brain.
A role for the GIRK3 subunit in methamphetamine-induced attenuation of GABAB receptor-activated GIRK currents in VTA dopamine neurons. Munoz MB, Padgett CL, Rifkin R, Terunuma M, Wickman K, Contet C, Moss SJ and Slesinger PA. (2016) J. Neurosci (in press)
Construction of cell-based neurotransmitter fluorescently engineered reporters (CNiFERs) for optical detection of neurotransmitters in vivo Lacin M, Muller A, Kleinfeld D and Slesinger, PA (2016) Construction of cell-based neurotransmitter fluorescently engineered reporters (CNiFERs) for optical detection of neurotransmitters in vivo. Journal of Visualized Experiments (in press).
Stress and Cocaine Trigger Divergent and Cell Type-Specific Regulation of Synaptic Transmission at Single Spines in Nucleus Accumbens. Khibnik LA, Beaumont M, Doyle M, Heshmati M, Slesinger PA, Nestler EJ, Russo SJ. Biol Psychiatry. 2015 Jun 6. pii: S0006-3223(15)00471-0. doi:
GIRK3 gates activation of the mesolimbic dopaminergic pathway by ethanol. Herman MA, Sidhu H, Stouffer DG, Kreifeldt M, Le D, Cates-Gatto C, Munoz MB, Roberts AJ, Parsons LH, Roberto M, Wickman K, Slesinger PA, Contet C. Proc Natl Acad Sci USA. 2015 Jun 2;112(22):7091-6. doi: 10.1073/pnas.1416146112.
GIRK Channels Modulate Opioid-Induced Motor Activity in a Cell Type- and Subunit-Dependent Manner. Kotecki L, Hearing M, McCall NM, Marron Fernandez de Velasco E, Pravetoni M, Arora D, Victoria NC, Munoz MB, Xia Z, Slesinger PA, Weaver CD, Wickman K. J Neurosci. 2015 May 6;35(18):7131-42. doi: 10.1523/JNEUROSCI.5051-14.2015.
Chromatin landscape defined by repressive histone methylation during oligodendrocyte differentiation. Liu J, Magri L, Zhang F, Marsh NO, Albrecht S, Huynh JL, Kaur J, Kuhlmann T, Zhang W, Slesinger PA, Casaccia P. J Neurosci. 2015 Jan 7;35(1):352-65. doi: 10.1523/JNEUROSCI.2606-14.2015.
Novel mechanism of voltage-gated N-type (Cav2.2) calcium channel inhibition revealed through α-conotoxin Vc1.1 activation of the GABA(B) receptor. Huynh TG, Cuny H, Slesinger PA, Adams DJ. Mol Pharmacol. 2015 Feb;87(2):240-50. doi: 10.1124/mol.114.096156
Cell-based reporters reveal in vivo dynamics of dopamine and norepinephrine release in murine cortex. Muller A, Joseph V, Slesinger PA, Kleinfeld D. Nat Methods. 2014 Dec;11(12):1245-52. doi: 10.1038/nmeth.3151. Epub 2014 Oct 26.
Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response. Munoz MB, Slesinger PA. Neuron. 2014 May 7;82(3):659-69. doi: 10.1016/j.neuron.2014.03.011.
Firing modes of dopamine neurons drive bidirectional GIRK channel plasticity. Lalive AL, Munoz MB, Bellone C, Slesinger PA, Lüscher C, Tan KR. J Neurosci. 2014 Apr 9;34(15):5107-14. doi: 10.1523/JNEUROSCI.5203-13.2014.
Molecular mechanism underlying ethanol activation of G-protein-gated inwardly rectifying potassium channels. Bodhinathan K, Slesinger PA. Proc Natl Acad Sci USA. 2013 Nov 5;110(45):18309-14. doi: 10.1073/pnas.1311406110.
Ras-association domain of sorting Nexin 27 is critical for regulating expression of GIRK potassium channels. Balana B, Bahima L, Bodhinathan K, Taura JJ, Taylor NM, Nettleton MY, Ciruela F, Slesinger PA. PLoS One. 2013;8(3):e59800. doi: 10.1371/journal.pone.0059800.
Methamphetamine-evoked depression of GABA(B) receptor signaling in GABA neurons of the VTA. Padgett CL, Lalive AL, Tan KR, Terunuma M, Munoz MB, Pangalos MN, Martínez-Hernández J, Watanabe M, Moss SJ, Luján R, Lüscher C, Slesinger PA. Neuron. 2012 Mar 8;73(5):978-89. doi: 10.1016/j.neuron.2011.12.031.
Meet the Team
Columbia Univ: PhD in Pharmacology & Molecular Signaling
A postdoctoral position is available in the Slesinger laboratory at the Icahn School of Medicine at Mount Sinai in New York City. We are supported by the NIH BRAIN initiative and are developing cell-based detectors, called CNiFERs, that can be implanted in a mouse brain and detect the release of specific neurotransmitters in real time. We developed the first optical biosensors to distinguish dopamine and norepinephrine. We are currently constructing new CNiFERs for the detection of neuropeptides in the brain. The project involves cell-based fluorescence assays, knowledge of G protein signaling, and fluorescence imaging. We are looking for enthusiastic candidates, with an interest in solving fundamental questions about the role of neuropeptides in brain function. Candidates should have a recent PhD in Neuroscience or other relevant field and first-author publication(s) from PhD. Interested candidates should send a curriculum vitae, a brief description of their research goals, and the names of three references to firstname.lastname@example.org.