The objective of this research project is to study the regulation of expression of the a4 subunit of the GABAA receptor (GABAA-R), which shows a degree of plasticity that is remarkable among the family of GABAA-R subunits, with a striking increase in expression during a variety of hyper-excitability syndromes, such as withdrawal from chronic intermittent ethanol (CIE) exposure. The genetic elements responsible for the control of expression of the mouse GABAA-R a4 subunit will be studied.
The specific aims of the present proposal are: 1) To clone the gene encoding the mouse GABAA-R a4 subunit (GABRA4), including the putative 5'-regulatory domain, and to characterize the gene structure and exon/intron boundaries. 2) To investigate the transcriptional start sites for mRNA species encoding the GABAA-R a4 subunit. 3) To investigate and characterize putative silencer, enhancer, initiator and/or positional regulator element/s in the mouse a4-subunit gene. Expression of the a4 subunit is limited to specific populations of neurons and is absent in non-neuronal cells - this may be due to the existence of one or more neuron-restrictive silencer elements in the 5'-regulatory domain of the gene. 4) To develop a cell line or primary neuronal culture system to study the regulation of expression of the GABAA-R a4 subunit, that will recapitulate key features of the induction of this gene in vivo in models of hyperexcitability. Repeated administration of alcohol, either to neurons in primary culture, or to a cell line model, results in induction of expression of the a4 subunit, and that this increased expression can be regulated by the inhibition of specific signaling pathways associated with transcriptional regulation. The completion of these Aims will increase our knowledge of a GABAA-R subunit that is associated with behavioral hyperexcitability and shows substantial plasticity. This knowledge will be useful in the study of transcriptional mechanisms involved in the induction of GABAA-R subunit expression, and potentially in designing interventions aimed at interrupting genomic mechanisms associated with withdrawal hyperexcitability.
| Chandra, Dev; Werner, David F; Liang, Jing et al. (2008) Normal acute behavioral responses to moderate/high dose ethanol in GABAA receptor alpha 4 subunit knockout mice. Alcohol Clin Exp Res 32:10-8 |
| Trudell, James R; Yue, Minerva E; Bertaccini, Edward J et al. (2008) Molecular modeling and mutagenesis reveals a tetradentate binding site for Zn2+ in GABA(A) alphabeta receptors and provides a structural basis for the modulating effect of the gamma subunit. J Chem Inf Model 48:344-9 |
| Chandra, D; Jia, F; Liang, J et al. (2006) GABAA receptor alpha 4 subunits mediate extrasynaptic inhibition in thalamus and dentate gyrus and the action of gaboxadol. Proc Natl Acad Sci U S A 103:15230-5 |
| Ma, Limei; Song, Lihua; Radoi, Gina E et al. (2004) Transcriptional regulation of the mouse gene encoding the alpha-4 subunit of the GABAA receptor. J Biol Chem 279:40451-61 |
