9 Genome-wide Views of Aging Gene Networks

Abstract

Aging is a complex process involving the additive effects of many genetic pathways (Kirkwood and Austad 2000). To embrace the complexity of aging, an attractive approach is to use DNA microarrays to scan the entire genome for genes that change expression as a function of age or under conditions when longevity is extended. The list of age-regulated genes provides clues about genetic pathways and mechanisms that underlie the aging process. In addition to single-gene analysis, the combined transcriptional profile of aging can act as a molecular phenotype of old age. During the last 20 years, there has been a great deal of effort to search for biomarkers of aging, and recent studies have shown that expression profiles of aging derived from DNA microarray experiments may provide this long-desired goal. A gene expression signature for aging is a quantitative phenotype that gives a high-resolution view of the aging process, much like using transcriptional profiles of cancer to inform about their severity or malignancy. Previously, one could recognize old versus young individuals in a photograph, or old versus young tissue on a microscope slide. Now it is possible to recognize old versus young genetic networks by analyzing expression levels of the entire set of age-regulated genes (Fig. 1). Unlike photographs or micrographs, expression data from DNA microarrays are quantitative, and thus it is possible to compare age-related transcriptional profiles between different tissues, between different conditions that affect longevity, and even between diverse species. Such comparisons are not possible by browsing images of...