The ionotropic glutamate receptors are critical for the normal development and function of the nervous system, and for the processes underlying learning and memory. Glutamate receptors have also been implicated in the etiology of several pathological conditions, including Alzheimer's, Huntington's and Parkinson's diseases, amyotrophic lateral sclerosis, epilepsy and brain damage following stroke. The proposed experiments will provide significant new information regarding regulation of the channel properties of AMPA receptors, the major glutamate receptor subtype mediating fast excitatory synaptic transmission in the brain. Stargazin is a transmembrane protein that is known to act as a molecular chaperone in trafficking of AMPA receptors to the cell surface. However, as an associated membrane protein, stargazin could also affect AMPA receptor channel function. Preliminary data document significant effects of stargazin on AMPA receptor desensitization that appear to be distinct from its effects on trafficking. Studies are proposed that will (1) identify the specific effects of stargazin on gating and desensitization of the AMPA channel; (2) identify the regions of interaction between stargazin and the AMPA receptor that mediate these functional effects, and; (3) determine the underlying mechanism for TARP modulation of AMPA receptors. Stargazin will be co-expressed with recombinant AMPA receptors in HEK 293 cells, as well as native AMPA receptors in cultured rat hippocampal neurons and mouse cerebellar granule cells. Functional effects on agonist- evoked and synaptic responses will be examined using patch-clamp recording from single cells. Molecular techniques will be applied to determine whether the regions of the stargazin protein that mediate trafficking and effects on channel function can be distinguished. Further experiments will involve manipulations of AMPA receptor proteins to attempt to disrupt the effects of stargazin on channel function. ? ?
|Levchenko-Lambert, Yanina; Turetsky, Dorothy M; Patneau, Doris K (2011) Not all desensitizations are created equal: physiological evidence that AMPA receptor desensitization differs for kainate and glutamate. J Neurosci 31:9359-67|