The C. elegans developmental timing protein LIN-42 regulates diapause in response to environmental cues.
Environmental conditions can have a major impact on developmental progression in animals. For example, when C. elegans larvae encounter harsh conditions they can reversibly halt the passage of developmental time by forming a long-lived dauer larva at the end of the second larval stage. Here, we show that the period homolog lin-42, known to control developmental time, also acts as a component of a switch that mediates dauer entry. Loss of lin-42 function renders animals hypersensitive to dauer formation under stressful conditions, whereas misexpression of lin-42 in the pre-dauer stage inhibits dauer formation, indicating that lin-42 acts as a negative regulator of this life history decision. These phenotypes place LIN-42 in opposition to the ligand-free form of the nuclear receptor DAF-12, which indirectly senses environmental conditions and helps to integrate external cues into developmental decisions. Mutations that impair DAF-12 ligand binding are exquisitely sensitive to the absence of lin-42, whereas overexpression of LIN-42 can suppress the dauer constitutive phenotype of a ligand-insensitive daf-12 mutant, suggesting that LIN-42 and DAF-12 are intimate partners in controlling the decision to become a dauer larva. The functional outputs of Period family proteins and nuclear receptors also converge in other organisms, suggesting that the relationship between lin-42 and daf-12 represents an ancient genetic framework for responding to environmental stimuli.
Tennessen
Jason M
JM
Department of Genetics, Cell Biology and Development, University of Minnesota, 321 Church Street SE, Minneapolis, MN 55455, USA.
Opperman
Karla J
KJ
Rougvie
Ann E
AE
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism* / Q000502:physiology; D003463:Cues; D017931:DNA Primers / Q000235:genetics; D004777:Environment; D008018:Life Cycle Stages / Q000502:physiology*; D056950:Period Circadian Proteins / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology; D020798:Two-Hybrid System Techniques
D029742:Caenorhabditis elegans Proteins; C410905:DAF-12 protein, C elegans; D017931:DNA Primers; C400538:LIN-42 protein, C elegans; D056950:Period Circadian Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors