AGEMAP: a gene expression database for aging in mice
We present the AGEMAP gene expression database, which is a resource cataloging genome-wide changes in gene expression as a function of age in mice. The AGEMAP database includes expression changes for 8,932 genes in 16 tissues as a function of age. We found great heterogeneity in the amount of transcriptional changes with age in different tissues. Some tissues displayed large transcriptional differences in old mice, suggesting that these tissues may contribute strongly to organismal decline. Other tissues showed little or no changes in expression with age, indicating strong levels of homeostasis throughout life. Based on the pattern of age-related transcriptional changes, we found that most tissues could be classified into one of three distinct modes for aging: a pattern common to neural tissues, a pattern for vascular tissues, and a pattern for glandular tissues. We observed that different tissues age in a coordinated fashion in individual mice, such that certain individual mice exhibit rapid aging whereas other individuals exhibit slow aging for multiple tissues. Finally, we compared the transcriptional profiles for aging in mice to those from humans, flies and worms. We found that genes involved in the electron transport chain show common age-regulation in all four species, indicating that these genes may be exceptional good markers of age. However, we saw no overall correlation between age-regulation in mice and in humans, indicating that the aging process in mice and humans may be fundamentally different.