The overall goal of this proposal is to study the role of methyl-lysine signaling by the nuclear factor kappa B (NF-kB) transcription factor in the epigenetic control of gene transcription during memory formation. Specifically, it will investigate whether the NF-kB p65 subunit acts as an initiator of epigenetic mechanisms through its recruitment of the histone methyltransferase G9a-like protein (GLP), mediator of the histone 3 lysine 9 di-methyl mark (H3K9me2). The first specific aim will test the hypothesis that the lysine methyltransferase SETD6 regulates monomethylation of p65 at lysine 310 (p65K310me1) and H3K9me2 changes in the hippocampus during memory consolidation, and will characterize these changes. The second specific aim will test whether p65K310me1 promotes recruitment of GLP, thereby mediating H3K9me2 changes in the hippocampus during memory consolidation. The rationale for these investigations stems from recent studies in which SETD6 was shown to mediate p65K310me1, thereby promoting recruitment of GLP and subsequent H3K9me2. However, this mechanism has only been demonstrated in vitro, in the context of immune cells. Whether this occurs in the brain in response to learning, or is critical for memory consolidation is currently unknown. Similarly, whether p65 methylation mediates an epigenetic program of transcriptional control with behavioral consequences has not yet been investigated. Preliminary data from our lab suggests that p65K310me1 increases during memory consolidation. Furthermore, we have shown that p65 interacts with SETD6 in the rat hippocampus and that knockdown of SETD6 in the dorsal hippocampus results in impaired fear memory consolidation. Building on these findings, we will use Western blot analysis, chromatin and co- immunoprecipitation to measure p65K310me1, p65-GLP interaction, and H3K9me2 changes following knockdown and overexpression of SETD6 in vivo. Next, we will mimic p65K310me1 using plasmids to induce expression of constitutively-methylated p65K310. Finally, we will use ChIP-Seq to interrogate H3K9me2 changes across the genome following SETD6 knockdown during memory consolidation and identify memory- critical genes to explain our behavioral findings. Relevance to public health: Granted that many cognitive disorders feature changes in the epigenetic control of gene expression and that NF-?B plays a known role in the epigenetic pathophysiology of cognitive disorders like Alzheimer's disease, the proposed experiments will begin to establish the mechanisms by which transcription factors initiate epigenetic changes in the brain. Moreover, these studies may identify new therapeutic strategies to mitigate cognitive symptoms of psychiatric conditions related to traumatic memories, such as post-traumatic stress disorders, phobias, and depression.
Initiation of epigenetic mechanisms governing gene transcription during memory formation are poorly understood. In this study, we seek to investigate the role of NF-kB p65 methylation and its effect on histone methylation in the brain. Because epigenetic mechanisms are known to be dysregulated in disorders of memory, this research may shed light on the pathophysiology of neurodegenerative disease and identify new therapeutic strategies for cognitive symptoms.
