Comparison of Epidermal Gene Expression Profiles in Mice Aged 1 to 20 Months

Introduction: Although it is well known that epidermal function changes with aging, the transcriptomic basis and possible signaling pathways for aging-associated functional changes remain largely unknown. Methods: Here, we employed RNA sequencing techniques to assess epidermal gene expression profiles in the epidermis of mice aged 1, 2, 6, 12 and 20 months. Results: A total of 132 genes displayed reductions in expression levels with aging, while expression levels of 406 genes increased with aging. Epidermal gene expression was prominently upregulated in 2-month-old vs 1-month-old mice, while more genes were downregulated in 12-month-old mice. Upregulation of genes associated with immune/inflammatory responses was observed in the epidermis of aged mice in comparison to that of young mice, whereas downregulated signaling pathways in the epidermis of aged mice were primarily involved in metabolism, such as fatty acid elongation, glutathione metabolism and biosynthesis of antibiotics. Some signaling pathways, such as chemokine signaling, cytokine/cytokine receptor interaction signaling and IL-17 signaling pathways, were remarkably upregulated in 12-month-old mice. Steroid synthesis, metabolic pathway, thermogenesis and proteasome pathways were steadily downregulated, starting at 2 months old. Conclusion: These results indicate that the epidermis of aged mice displays an upregulation of genes associated with inflammatory signaling pathways, and downregulation of genes related to metabolic signaling pathways.