Single nucleotide polymorphisms (SNPs) in the
FK506 binding protein 5 (FKBP5) gene combine with traumatic events to increase risk for post-traumatic stress and
major depressive disorders (
PTSD and MDD). These SNPs increase FKBP51
protein expression through a mechanism involving demethylation of the gene and altered
glucocorticoid signaling. Aged animals also display elevated FKBP51 levels, which contribute to impaired resiliency to depressive-like behaviors through impaired
glucocorticoid signaling, a phenotype that is abrogated in FKBP5-/- mice. But the age of onset and progressive stability of these phenotypes remain unknown. Moreover, it is unclear how FKBP5 deletion affects other
glucocorticoid-dependent processes or if age-associated increases in FKBP51 expression are mediated through a similar epigenetic process caused by SNPs in the FKBP5 gene. Here, we show that FKBP51-mediated impairment in stress resiliency and
glucocorticoid signaling occurs by 10 months of age and this increased over their lifespan. Surprisingly, despite these progressive changes in
glucocorticoid responsiveness, FKBP5-/- mice displayed normal longevity,
glucose tolerance, blood composition and
cytokine profiles across lifespan, phenotypes normally associated with
glucocorticoid signaling. We also found that methylation of Fkbp5 decreased with age in mice, a process that likely explains the age-associated increases in FKBP51 levels. Thus, epigenetic upregulation of FKBP51 with age can selectively impair psychological stress-resiliency, but does not affect other
glucocorticoid-mediated physiological processes. This makes FKBP51 a unique and attractive therapeutic target to treat
PTSD and MDD. In addition, aged wild-type mice may be a useful model for investigating the mechanisms of FKBP5 SNPs associated with these disorders.