?-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 #
3R01NS056359-04S1
Application #
7848452
Study Section
Special Emphasis Panel (ZRG1-MDCN-G (93))
Program Officer
Silberberg, Shai D
Project Start
2007-04-01
Project End
2010-08-31
Budget Start
2009-07-20
Budget End
2010-08-31
Support Year
4
Fiscal Year
2009
Total Cost
$22,096
Indirect Cost
Name
Tufts University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
039318308
City
Boston
State
MA
Country
United States
Zip Code
02111
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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
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