The effects of aging on the expression of Wnt pathway genes in mouse tissues.

The Wnt signaling pathway is involved in the regulation of tissue patterning and organ development during embryogenesis and continues to contribute to the maintenance of tissue homeostasis in adulthood. Recently, Wnt signaling has also been implicated in the establishment and progression of replicative cellular senescence. Given the known roles of tissue homeostasis and cellular senescence in aging, we sought to determine whether Wnt signaling changes with age. We examined the expression of 84 Wnt pathway-related genes in the liver, lung, skeletal muscle, and brain tissue from young and old mice. Expression changes were compared with those seen in cellular senescence, and transcription factors that might mediate these changes were predicted bioinformatically. In aggregate, our data are indicative of a general decrease in Wnt signaling with age, especially in the lung and brain. Furthermore, the set of genes that are differentially expressed with age is distinct from the genes differentially expressed in cellular senescence. The transcription factors predicted to regulate these changes, Nf-κB, Myb, Nkx2-1, Nr5a2, and Ep300, are known to regulate inflammation, differentiation, lipid metabolism, and chromatin remodeling, all of which have previously been implicated in aging. Although our study does not address whether altered Wnt signaling is a cause or an effect of aging, the presence of a relationship between the two provides a starting point for further investigation.