steroids as central regulators of organismal development and lifespan类固醇生物的发展和寿命的中央监管机构.pdf

Primer Steroids as Central Regulators of Organismal Development and Lifespan 1 2 Siu Sylvia Lee *, Frank C. Schroeder * 1 Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America, 2 Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America The Dauer Pheromone Abstract: Larvae of the nematode Caenorhabditis elegans must choose between reproductive development and The major environmental cues that regulate dauer formation dauer diapause. This decision is based on sensing of include food, temperature, and a small molecule signal constitu- environmental inputs and dauer pheromone, a small tively produced by the worms: the dauer pheromone [3,4]. molecule signal that serves to monitor population density. Elevated pheromone levels caused, for example, by over-crowding These signals are integrated via conserved neuroendo- are a strong cue for dauer entry. Extensive studies in the past few crine pathways that converge on steroidal ligands of the decades have revealed a complex network of signaling pathways nuclear receptor DAF-12, a homolog of the mammalian that regulate the decision on reproductive maturation versus dauer vitamin D receptor and liver X receptor. DAF-12 acts as diapause. Early mutagenesis screens identified a large number of the main switch between gene expression programs that