Moreover, the application of genome-wide tools to this problem will enable examination of DNA methylation patterns find more in a much wider pool of genes, which is currently lacking. Finally, chromatin immunoprecipitation (ChIP) procedures also allow detection
of methyl-DNA binding proteins and specific histone modifications at the level of these and other specific gene loci. Additionally, new molecular biological methods have emerged for identifying changes in DNA methylation at the single-cell and single-allele level. Bisulfite sequencing, considered the “gold standard” for assaying DNA methylation, provides single-nucleotide information about a cytosine’s methylation state. Global analysis of all DNA from a given brain region cannot distinguish between DNA methylation changes in different cell types Sirolimus (e.g., neurons versus glial cells, glutamatergic versus GABAergic cells, etc.), which is a current limitation. However, bacterial
subcloning of single pieces of DNA, which originate from single alleles within a single cell, allows isolation of DNA from single CNS cells. Thus, direct bisulfite sequencing combined with DNA subcloning enables quantitative interrogation of single-allele changes in methylation, at the single nucleotide level, in single cells from brain tissue ( Miller et al., 2010). Such an approach may be especially powerful for interrogating the sparsely encoded, environmentally induced neuronal changes that occur during learning and memory. Overall,
these recent and emerging techniques pave the way for substantive experimental interrogation of experience-driven epigenetic changes, potentially aiding in the identification of an epigenetic code, that underlie memory formation. The ultimate challenge for future studies will be to determine in a comprehensive fashion how DNA methylation and chromatin remodeling at the single-cell level is regulated and translated into changes in neural circuit function and behavior in the context of learning and memory. The MAPK cascade was first established as the prototypic regulator of cell division and differentiation in nonneuronal cells (Bading and Greenberg, 1991, English and Sweatt, 1996, Fiore et al., 1993 and Murphy et al., 1994). Oxymatrine The prominent expression and activation of MAPKs in the mature nervous system, particularly in the hippocampus, prompted researchers to question the role of the MAPK cascade in terminally differentiated, nondividing neurons in the brain (Bading and Greenberg, 1991 and English and Sweatt, 1996). It was speculated that the cascade might have been co-opted in the mature nervous system to subserve synaptic plasticity and memory formation, thereby proposing a mechanism of molecular homology between cellular development and learning and memory (Atkins et al.