Age-related changes in Usp9x protein expression and DNA methylation in mouse brain.
Usp9x, a ubiquitin-specific protease implicated in synaptic development, was found to be more abundant in adult as compared to newborn mouse brain tissue. The Usp9x gene was less methylated in adults than in newborns in both the promoter and the protein coding region. Compared with newborns, the adult mouse brain also had lower levels of Dnmt1, the enzyme responsible for maintaining DNA methylation state. These age-associated changes in DNA methylation and ubiquitin system protein concentrations potentially contribute to developmental changes in brain structure and function.