Alcoholism and alcohol abuse are complicating factors in most chronic medical and psychiatric illnesses. Alcohol physiological dependence and associated withdrawal episodes are thought to constitute a powerful motivational force that perpetuates continued alcohol use/abuse and contributes to relapse. In humans, the identification of genes that influence alcohol physiological dependence and withdrawal has been extremely limited. Thus, the use of preclinical (animal) models of alcohol physiological dependence that closely approximate the clinical situation is essential to elucidate the gene networks involved. We have used these methods to identify a gene (Mpdz) involved in alcohol withdrawal in mice that is now being studied in populations of human alcoholics by NIH-NIAAA intramural scientists. Quantitative trait loci (QTLs) are chromosome sites containing alleles (genes) that influence a quantitative (complex) trait such as predisposition to alcohol physiological dependence and associated withdrawal. Previously, we confirmed QTLs on chromosomes (Chr) 1, 4, and 11 that jointly have a major influence on alcohol withdrawal in mice. This proposal is focused on the Chr 4 QTL with proven effects on acute and chronic ethanol withdrawal. During the current funding period, we fine mapped this QTL to a 1.8 Mb (<1 cM) interval (syntenic with human Chr 9p24-p22.3) and identified Mpdz (which encodes the multiple PDZ domain protein, MPDZ or MUPP1) as a quantitative trait gene (QTG) for alcohol withdrawal. Using a congenic strain that isolates this locus on an inbred genetic background as well as novel Mpdz transgenic animal models, we propose to continue toward elucidation of the mechanism by which Mpdz affects alcohol withdrawal. We propose the following three aims: (1) Using viral mediated gene transfer and/or RNA interference approaches, rigorously test the hypothesis that Mpdz expression in circuitry implicated in ethanol withdrawal in fact influences withdrawal severity. Pharmacological manipulation in discrete brain regions will provide mechanistic information about MPDZ and its influence on ethanol withdrawal. (2) Use neurochemical and neurophysiological analyses to provide mechanistic answers to identify a signal transduction pathway influenced by MPDZ. (3) Using congenic and Mpdz transgenic animal models, test Mpdz's role in behavioral responses to ethanol (i.e., acceptance drinking, conditioned taste aversion, ataxia sensitivity, and tolerance) that are genetically correlated with Mpdz status and expression, as well as other CNS hyperexcitability states. An innovative feature of this proposal is to combine robust behavioral models of alcohol withdrawal with state-of-the-art strategies to elucidate Mpdz's mechanism of action. MPDZ is thought to regulate 5HT2C and GABAB receptor function. Given the growing body of evidence that dysregulation of GABA and serotonin transmission contributes to alcoholism, we expect that our results will inform developing models and facilitate progress in human alcohol genetics by setting the stage for future translational and mechanistic studies. We have already established that a gene, Mpdz, substantially influences genetic risk for alcohol physiological dependence and associated withdrawal episodes in mice. This proposal is focused on explaining the mechanism by which Mpdz affects alcohol withdrawal, as well as determining its influence on other behavioral responses to alcohol. Given that Mpdz encodes a protein that regulates the function of serotonin and GABA receptors in the brain, and dysregulation of serotonin and GABA function contributes to alcoholism, we expect that the results of this research will facilitate progress in the treatment of alcohol dependence. NARRATIVE We have already established that a gene, Mpdz, substantially influences genetic risk for alcohol physiological dependence and associated withdrawal episodes in mice. This proposal is focused on explaining the mechanism by which Mpdz affects alcohol withdrawal, as well as determining its influence on other behavioral responses to alcohol. Given that Mpdz encodes a protein that regulates the function of serotonin and GABA receptors in the brain, and disregulation of serotonin and GABA function contributes to alcoholism, we expect that the results of this research will facilitate progress in the treatment of alcohol dependence.

Agency
National Institute of Health (NIH)
Institute
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Type
Research Project (R01)
Project #
5R01AA011114-13
Application #
8266554
Study Section
Special Emphasis Panel (ZRG1-IFCN-A (02))
Program Officer
Parsian, Abbas
Project Start
1997-08-01
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2014-04-30
Support Year
13
Fiscal Year
2012
Total Cost
$329,725
Indirect Cost
$115,618
Name
Oregon Health and Science University
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Kruse, L C; Walter, N A R; Buck, K J (2014) Mpdz expression in the caudolateral substantia nigra pars reticulata is crucially involved in alcohol withdrawal. Genes Brain Behav 13:769-76
Buck, K J; Walter, N A R; Denmark, D L (2014) Genetic variability of respiratory complex abundance, organization and activity in mouse brain. Genes Brain Behav 13:135-43
Tipps, Megan E; Raybuck, Jonathan D; Buck, Kari J et al. (2014) Delay and trace fear conditioning in C57BL/6 and DBA/2 mice: issues of measurement and performance. Learn Mem 21:380-93
Chen, G; Buck, K J (2010) Rostroventral caudate putamen involvement in ethanol withdrawal is influenced by a chromosome 4 locus. Genes Brain Behav 9:768-76
Kozell, Laura B; Walter, Nicole A R; Milner, Lauren C et al. (2009) Mapping a barbiturate withdrawal locus to a 0.44 Mb interval and analysis of a novel null mutant identify a role for Kcnj9 (GIRK3) in withdrawal from pentobarbital, zolpidem, and ethanol. J Neurosci 29:11662-73
Walter, Nicole A R; Bottomly, Daniel; Laderas, Ted et al. (2009) High throughput sequencing in mice: a platform comparison identifies a preponderance of cryptic SNPs. BMC Genomics 10:379
Reilly, Matthew T; Milner, Lauren C; Shirley, Renee L et al. (2008) 5-HT2C and GABAB receptors influence handling-induced convulsion severity in chromosome 4 congenic and DBA/2J background strain mice. Brain Res 1198:124-31
Shirley, Renee L; Walter, Nicole A R; Reilly, Matthew T et al. (2004) Mpdz is a quantitative trait gene for drug withdrawal seizures. Nat Neurosci 7:699-700
Fehr, C; Shirley, R L; Metten, P et al. (2004) Potential pleiotropic effects of Mpdz on vulnerability to seizures. Genes Brain Behav 3:8-19
Fehr, Christoph; Shirley, Renee L; Belknap, John K et al. (2002) Congenic mapping of alcohol and pentobarbital withdrawal liability loci to a <1 centimorgan interval of murine chromosome 4: identification of Mpdz as a candidate gene. J Neurosci 22:3730-8