DAF-12 Regulates a Connected Network of Genes to Ensure Robust Developmental Decisions

Division of Geriatric Medicine, Department of Medicine, University of Pittsburgh, Pennsylvania, United States of America.
PLoS Genetics (Impact Factor: 7.53). 07/2011; 7(7):e1002179. DOI: 10.1371/journal.pgen.1002179
Source: PubMed


The nuclear receptor DAF-12 has roles in normal development, the decision to pursue dauer development in unfavorable conditions, and the modulation of adult aging. Despite the biologic importance of DAF-12, target genes for this receptor are largely unknown. To identify DAF-12 targets, we performed chromatin immunoprecipitation followed by hybridization to whole-genome tiling arrays. We identified 1,175 genomic regions to be bound in vivo by DAF-12, and these regions are enriched in known DAF-12 binding motifs and act as DAF-12 response elements in transfected cells and in transgenic worms. The DAF-12 target genes near these binding sites include an extensive network of interconnected heterochronic and microRNA genes. We also identify the genes encoding components of the miRISC, which is required for the control of target genes by microRNA, as a target of DAF-12 regulation. During reproductive development, many of these target genes are misregulated in daf-12(0) mutants, but this only infrequently results in developmental phenotypes. In contrast, we and others have found that null daf-12 mutations enhance the phenotypes of many miRISC and heterochronic target genes. We also find that environmental fluctuations significantly strengthen the weak heterochronic phenotypes of null daf-12 alleles. During diapause, DAF-12 represses the expression of many heterochronic and miRISC target genes, and prior work has demonstrated that dauer formation can suppress the heterochronic phenotypes of many of these target genes in post-dauer development. Together these data are consistent with daf-12 acting to ensure developmental robustness by committing the animal to adult or dauer developmental programs despite variable internal or external conditions.

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    • "It will also be valuable to identify direct targets of DAF-16/FOXO and DAF-12/VDR in long-lived, GSC-ablated worms. Chromatin immunoprecipitation studies have identified DAF-16/FOXO direct targets (Oh et al., 2006) and DAF-12/VDR binding sites (Hochbaum et al., 2011), but the DNA-binding profiles of both proteins in a GSC-ablated background are yet to be discovered . These will likely provide clues to the relationship between these two key transcriptional regulators. "
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