Abstract
Aging is a complex phenotype responsive to a plethora of environmental inputs; yet only a limited number of transcriptional regulators are known to influence life span. How the downstream expression programs mediated by these factors (or others) are coordinated into common or distinct set of aging effectors is an addressable question in model organisms, such as C. elegans. Here, we establish the transcription factor ETS-4, an ortholog of vertebrate SPDEF, as a longevity determinant. Adult worms with ets-4 mutations had a significant extension of mean life span. Restoring ETS-4 activity in the intestine, but not neurons, of ets-4 mutant worms rescued life span to wild-type levels. Using RNAi, we demonstrated that ets-4 is required post-developmentally to regulate adult life span; thus uncoupling the role of ETS-4 in aging from potential functions in worm intestinal development. Seventy ETS-4-regulated genes, identified by gene expression profiling of two distinct ets-4 alleles and analyzed by bioinformatics, were enriched for known longevity effectors that function in lipid transport, lipid metabolism, and innate immunity. Putative target genes were enriched for ones that change expression during normal aging, the majority of which are controlled by the GATA factors. Also, some ETS-4-regulated genes function downstream of the FOXO factor, DAF-16 and the insulin/IGF-1 signaling pathway. However, epistasis and phenotypic analyses indicate that ets-4 functioned in parallel to the insulin/IGF-1 receptor, daf-2 and akt-1/2 kinases. Furthermore, ets-4 required daf-16 to modulate aging, suggesting overlap in function at the level of common targets that affect life span. In conclusion, ETS-4 is a new transcriptional regulator of aging, which shares transcriptional targets with GATA and FOXO factors, suggesting that overlapping pathways direct common sets of lifespan-related genes.
Animal life span is regulated in response to developmental and environmental inputs through coordinate changes in gene expression. Thus, longevity determinants include DNA-binding proteins that regulate gene expression by controlling transcription. Here, we explored the physiological role of the transcriptional regulator, ETS-4, in the roundworm Caenorhabditis elegans. Our data showed that worms that lack ETS-4 lived significantly longer, revealing ETS-4′s role in the transcription network that regulates life span. We identified 70 genes whose expression was modulated by ETS-4 that function in lipid transport, lipid metabolism and innate immunity. Some of the ETS-4-regulated genes were also controlled by two other regulators of aging, the FOXO and GATA factors. We concluded that a common set of transcriptional targets orchestrate the network of physiological factors that affect aging. ETS-4 is closely related to the human ETS protein SPDEF that exhibits aberrant expression in breast and prostate tumors. Because the genetic pathways that regulate aging are well conserved in other organisms, including humans, our findings could lead to a better understanding of SPDEF function and longevity regulation in mammals.
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