Memory formation is thought to be encoded by alterations in the effectiveness of synaptic co between neurons. Electrophysiological and behavioral studies have demonstrated that long-lasting synaptic plasticity requires protein synthesis. However, changes in efficacy of an individual synapse can occur independently of other synapses on the same cell, raising the question of how this specificity is achieved on a molecular level. One possibility is that local protein translation within dendrites, contributes to alterations in synaptic efficacy. Although most mRNA species are restricted to the cell soma, a small subset have also been found in dendrites, including the mRNA encoding the alpha subunit of calcium-calmodulin dependent protein kinase type 11 (CaMKIIalpha). In a previous study the proposed sponsor, Dr. Mark Mayford, demonstrated that the 3' untranslated region (UTR) of the CAMKIIalpha mRNA contains a cis-acting signal controlling dendritic localization. The two specific aims of this proposal are as follows: 1) Examine the correlation between synaptic potentiation and dendritic translation using hippocampal slices from transgenic mice expressing a green fluorescent protein (GFP)-lacZ reporter construct fused to the dendritic targeting element from CAMKIIalpha mRNA. Using this dendritic reporter preparation will allow visualization of changes in dendritic protein in real time in a living slice. 2) Determine whether dendritic CAMKIIalpha mRNA is necessary for synaptic and behavioral plasticity. This will be accomplished using a gene-targeting approach to produce mutant mice in which the normal 3'UTR of the CAMKIIalpha gene is replaced with the polyadenylation signal from bovine growth hormone. The objective is to produce a mouse without dendritic CAMKIIalpha mRNA but with normal levels of CAMKIIalpha mRNA in the cell soma for use in both electrophysiological and behavioral studies of plasticity. These experiments will provide insight into the role of dendritic translation in memory formation. Characterization of such mechanisms is a requisite step in identifying the molecular and cellular etiology of each of the various pathological conditions in which memory is affected.
