| Title: | Hormonal signal amplification mediates environmental conditions during development and controls an irreversible commitment to adulthood |
| Author(s): | Schaedel ON; Gerisch B; Antebi A; Sternberg PW; |
| Address: | "Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, Pasadena, California, United States of America" |
| DOI: | 10.1371/journal.pbio.1001306 |
| ISSN/ISBN: | 1545-7885 (Electronic) 1544-9173 (Print) 1544-9173 (Linking) |
| Abstract: | "Many animals can choose between different developmental fates to maximize fitness. Despite the complexity of environmental cues and life history, different developmental fates are executed in a robust fashion. The nematode Caenorhabditis elegans serves as a powerful model to examine this phenomenon because it can adopt one of two developmental fates (adulthood or diapause) depending on environmental conditions. The steroid hormone dafachronic acid (DA) directs development to adulthood by regulating the transcriptional activity of the nuclear hormone receptor DAF-12. The known role of DA suggests that it may be the molecular mediator of environmental condition effects on the developmental fate decision, although the mechanism is yet unknown. We used a combination of physiological and molecular biology techniques to demonstrate that commitment to reproductive adult development occurs when DA levels, produced in the neuroendocrine XXX cells, exceed a threshold. Furthermore, imaging and cell ablation experiments demonstrate that the XXX cells act as a source of DA, which, upon commitment to adult development, is amplified and propagated in the epidermis in a DAF-12 dependent manner. This positive feedback loop increases DA levels and drives adult programs in the gonad and epidermis, thus conferring the irreversibility of the decision. We show that the positive feedback loop canalizes development by ensuring that sufficient amounts of DA are dispersed throughout the body and serves as a robust fate-locking mechanism to enforce an organism-wide binary decision, despite noisy and complex environmental cues. These mechanisms are not only relevant to C. elegans but may be extended to other hormonal-based decision-making mechanisms in insects and mammals" |
| Keywords: | "Adaptation, Physiological Animals Caenorhabditis elegans/cytology/*growth & development/metabolism Caenorhabditis elegans Proteins/genetics/metabolism Cholestenes/*metabolism Cytochrome P-450 Enzyme System/genetics/metabolism Environment Feedback, Physiol;" |
| Notes: | "MedlineSchaedel, Oren N Gerisch, Birgit Antebi, Adam Sternberg, Paul W eng T32 GM007616/GM/NIGMS NIH HHS/ GM07676/GM/NIGMS NIH HHS/ R01AG027498/AG/NIA NIH HHS/ HHMI/Howard Hughes Medical Institute/ R01 AG027498/AG/NIA NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2012/04/17 PLoS Biol. 2012; 10(4):e1001306. doi: 10.1371/journal.pbio.1001306. Epub 2012 Apr 10" |
