?-aminobutyric acid (GABAA) receptors are key sites of synaptic inhibition in the brain and are critical drug targets for therapeutic agents including benzodiazepines, barbiturates, general anesthetics and neurosteroids. Moreover compromised GABAA receptor function is central to a number of CMS pathologies including epilepsy, anxiety, sleep disorders, addiction, autism, mental retardation, depression and schizophrenia. Ubiquitination of lysine residues is a commonly used cellular mechanism to regulate both protein half-life and the endocytic fate. This accepted paradigm together with our preliminary studies has led us to formulate a central hypothesis driving the experiments described in this proposal: GABAA receptors are subject to direct ubiquitination of lysine residues with the intracellular domains of individual receptor subunits, a process that is subject to dynamic modulation by neuronal activity. Depending on the subunit ubiquitinated this covalent modification acts to decrease receptor half-life within the secretory pathway or enhances lysozomal targeting, thereby modulating GABAA receptor cell surface stability and the efficacy of synaptic inhibition. Our efforts will center on four complementary but distinct experimental goals: 1. To test the hypothesis that GABAA receptor ?3 subunit ubiquitination regulates receptor cell surface stability by modulating insertion at the plasma membrane 2. To test the hypothesis that GABAA receptor ?2 subunit ubiquitination regulates receptor cell surface stability by modulating lysozomal targeting 3. To test the hypothesis that ubiquitination modulates the efficacy of synaptic inhibition mediated by GABAA receptors 4. To test the hypothesis that neuronal activity regulates GABAA receptor cell surface stability by modulating receptor ubiquitination Together, our approaches will provide a more thorough understanding of the primary determinants that regulate accumulation of GABAA receptors at synaptic sites. The results of these studies will have the potential to make significant contributions to the development of novel therapeutic strategies for such debilitating disorders as epilepsy, anxiety, sleep disorders, addiction, autism, mental retardation, depression and schizophrenia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS056359-05
Application #
7800387
Study Section
Special Emphasis Panel (ZRG1-MDCN-G (93))
Program Officer
Silberberg, Shai D
Project Start
2007-04-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2012-03-31
Support Year
5
Fiscal Year
2010
Total Cost
$357,329
Indirect Cost
Name
Tufts University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
039318308
City
Boston
State
MA
Country
United States
Zip Code
02111
Modgil, Amit; Parakala, Manasa L; Ackley, Michael A et al. (2017) Endogenous and synthetic neuroactive steroids evoke sustained increases in the efficacy of GABAergic inhibition via a protein kinase C-dependent mechanism. Neuropharmacology 113:314-322
Wobst, Heike J; Wesolowski, Steven S; Chadchankar, Jayashree et al. (2017) Cytoplasmic Relocalization of TAR DNA-Binding Protein 43 Is Not Sufficient to Reproduce Cellular Pathologies Associated with ALS In vitro. Front Mol Neurosci 10:46
Kang, Ji-Yong; Chadchankar, Jayashree; Vien, Thuy N et al. (2017) Deficits in the activity of presynaptic ?-aminobutyric acid type B receptors contribute to altered neuronal excitability in fragile X syndrome. J Biol Chem 292:6621-6632
Nakamura, Yasuko; Morrow, Danielle H; Modgil, Amit et al. (2016) Proteomic Characterization of Inhibitory Synapses Using a Novel pHluorin-tagged ?-Aminobutyric Acid Receptor, Type A (GABAA), ?2 Subunit Knock-in Mouse. J Biol Chem 291:12394-407
Vien, Thuy N; Moss, Stephen J; Davies, Paul A (2016) Regulating the Efficacy of Inhibition Through Trafficking of ?-Aminobutyric Acid Type A Receptors. Anesth Analg 123:1220-1227
Kelley, Matthew R; Deeb, Tarek Z; Brandon, Nicholas J et al. (2016) Compromising KCC2 transporter activity enhances the development of continuous seizure activity. Neuropharmacology 108:103-10
Walker, Kendall R; Modgil, Amit; Albrecht, David et al. (2016) Genetic Deletion of the Clathrin Adaptor GGA3 Reduces Anxiety and Alters GABAergic Transmission. PLoS One 11:e0155799
Mircsof, Dennis; Langouët, Maéva; Rio, Marlène et al. (2015) Mutations in NONO lead to syndromic intellectual disability and inhibitory synaptic defects. Nat Neurosci 18:1731-6
Sivakumaran, Sudhir; Cardarelli, Ross A; Maguire, Jamie et al. (2015) Selective inhibition of KCC2 leads to hyperexcitability and epileptiform discharges in hippocampal slices and in vivo. J Neurosci 35:8291-6
Silayeva, Liliya; Deeb, Tarek Z; Hines, Rochelle M et al. (2015) KCC2 activity is critical in limiting the onset and severity of status epilepticus. Proc Natl Acad Sci U S A 112:3523-8

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