The overarching hypothesis in this proposal states that a CREB-regulated microRNA (miR-132) is involved in modulating hippocampus dependent synaptic plasticity, and memory. The primary hypothesis is supported by the ideas that (1) CREB mediated transcription is required for hippocampus dependent memory, and that (2) modulation of protein synthesis is necessary for long-lasting hippocampal synaptic plasticity. Stimulus- dependent, CREB-driven, expression of a miRNA may add a new layer of control over protein synthesis and may specifically modify the proteome of activated synapses. To determine if miR-132 plays a role in hippocampal synaptic plasticity, the first aim of this proposal intends to characterize the level, and kinetics, of expression of miR-132 following contextual fear conditioning. I plan on characterizing the time course of expression of the primary form of miR-132 (pri-miR-132), as well as the mature (active) form of miR-132 using SyBR green and TaqMan based RT- qPCR. I have preliminary data showing a significant increase in the pri-mir-132 transcript 30 minutes following contextual fear conditioning compared to controls. Interestigly, my preliminary data shows a signficant increase in the mature miR-132 transcript at least 24 hours following contextual fear conditioning compared to controls. In the second aim, I propose to utilize a miR-132 inhibitor known as an 'antagomir'. The antagomir for miR-132 will be infused into the hippocampus of cannulated mice. This tool will allow investigation of the role miR-132 plays in hippocampus dependent learning and memory. I also plan to test the antagomir's effects on late-phase LTP (L-LTP) evoked in the CA3/CA1 Schaeffer-collateral synapse. L-LTP will be examined due to the requirement of cAMP signal transduction, and de novo gene transcription. Additionally, it is known that L-LTP stimulates CRE-mediated gene expression. Finally, It has been shown that methyl-CpG-binding protein 2 (MeCP2) is a target for miR-132. I plan on asking whether MeCP2 levels are altered following training for contextual fear conditioning and if these changes are due to miR-132 increases. Interestingly, alterations in MeCP2 levels are associated with Rett Syndrome, a neurodevelopmental disorder, in humans. This proposal will directly contribute to the mission of NINDS and NIMH. The investigation will strive to gain insight on new mechanisms underlying the basic science of learning and memory. The proposal is centered around microRNAs, powerful regulators of gene expression, with tremendous therapeutic promise. The potential for translating this basic research into therapeutic gain for memory disorders, such as Alzheimer's disease, is particularly exciting due to the nature of the mechanism proposed.
| Nudelman, Aaron S; DiRocco, Derek P; Lambert, Talley J et al. (2010) Neuronal activity rapidly induces transcription of the CREB-regulated microRNA-132, in vivo. Hippocampus 20:492-8 |
