| Intracellular receptors are transcription factors, commonly regulated by small lypophilic molecules including hormones, metabolites, drugs and xenobiotics that function in numerous critical physiological processes, such as development, metabolism, homeostasis regulation, and aging, in mammals, flys, and worms. In the nematode Caenorhabditis elegans, intracellular receptor DAF-12 regulates animal development and aging. In this study, we conducted the first mechanistic characterization of DAF-12 function at the molecular level. We developed a novel method, In Vitro Genomic Selection, which enabled us, starting from the C. elegans genome, to identify and characterize DAF-12 DNA binding sites, response elements, and the first target gene. Furthermore, based on the discovery of the response elements, we began to explore DAF-12 domain function, uncovering a putative transcriptional activation surface, specialized DNA binding and multiple subcellular localization determinants. This work represents the first steps in our endeavor to decipher, specifically, how molecular actions of a transcriptional regulator, such as DAF-12, translate into defined biological outputs, and, in general, the mechanics of cellular and organismal regulatory networks. |
