Ubiquitination of Histone H2B by Proteasome Subunit RPT6 Controls Histone Methylation Chromatin Dynamics During Memory Formation.

Background: Posttranslational histone modifications play a critical role in the regulation of gene transcription underlying synaptic plasticity and memory formation. One such epigenetic change is histone ubiquitination, a process that is mediated by the ubiquitin-proteasome system in a manner similar to that by which proteins are normally targeted for degradation. However, histone ubiquitination mechanisms are poorly understood in the brain and in learning.

EZH2 Methyltransferase Activity Controls Pten Expression and mTOR Signaling during Fear Memory Reconsolidation.

Memory retrieval induces a transient period of increased transcriptional and translational regulation in neurons called reconsolidation, which is regulated by the protein kinase B (AKT)-mammalian target of rapamycin (mTOR) pathway. However, it is currently unknown how activation of the AKT-mTOR pathway is regulated during the reconsolidation process. Here, we found that in male rats retrieval of a contextual fear memory transiently increased Enhancer of Zeste Homolog 2 (EZH2) levels along with increased histone H3 lysine 27 trimethylation (H3K27me3) levels, which correlated with decreased levels of phosphatase and tensin homolog (PTEN), a potent inhibitor of AKT-mTOR-dependent signaling in the hippocampus.