UMMS Affiliation

Program in Molecular Medicine

Publication Date


Document Type



Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; *Environment; *Feedback, Physiological; Gene Expression Regulation, Developmental; Ligands; MicroRNAs; Models, Biological; Mutation; Receptors, Cytoplasmic and Nuclear; Time Factors


Developmental Biology | Genetics | Molecular Biology | Molecular Genetics


Animal development is remarkably robust; cell fates are specified with spatial and temporal precision despite physiological and environmental contingencies. Favorable conditions cause Caenorhabditis elegans to develop rapidly through four larval stages (L1-L4) to the reproductive adult. In unfavorable conditions, L2 larvae can enter the developmentally quiescent, stress-resistant dauer larva stage, enabling them to survive for prolonged periods before completing development. A specific progression of cell division and differentiation events occurs with fidelity during the larval stages, regardless of whether an animal undergoes continuous or dauer-interrupted development. The temporal patterning of developmental events is controlled by the heterochronic genes, whose products include microRNAs (miRNAs) and regulatory proteins. One of these proteins, the DAF-12 nuclear hormone receptor, modulates the transcription of certain let-7-family miRNAs, and also mediates the choice between the continuous vs. dauer-interrupted life history. Here, we report a complex feedback loop between DAF-12 and the let-7-family miRNAs involving both the repression of DAF-12 by let-7-family miRNAs and the ligand-modulated transcriptional activation and repression of the let-7-Fam miRNAs by DAF-12. We propose that this feedback loop functions to ensure robustness of cell fate decisions and to coordinate cell fate with developmental arrest.


gene regulation, microRNA, nuclear hormone receptor

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DOI of Published Version



Proc Natl Acad Sci U S A. 2009 Nov 3;106(44):18668-73. doi: 10.1073/pnas.0908131106. Epub 2009 Oct 14. Link to article on publisher's site

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

Related Resources

Link to Article in PubMed

PubMed ID