The 14-3-3 protein FTT-2 regulates DAF-16 in Caenorhabditis elegans.
The Caenorhabditis elegans daf-2/insulin-like signaling pathway is critical for regulating development, longevity, metabolism and stress resistance. We identified the 14-3-3 protein FTT-2 to be a new regulatory component of this pathway. We found that RNAi knock down of ftt-2 specifically enhanced the daf-2-mediated dauer formation phenotype. Furthermore, ftt-2 knock down caused the nuclear accumulation of DAF-16/FOXO, the forkhead transcription factor that is the major downstream effecter of daf-2/insulin-like signaling, and enhanced the transcriptional activities of DAF-16. In contrast to ftt-2, RNAi knock down of par-5/ftt-1, the only other gene predicted to encode a 14-3-3 protein in C. elegans, did not show any notable effect on dauer formation, DAF-16 localization, or DAF-16 downstream gene transcription, underscoring the functional specification of FTT-2 and PAR-5 despite their high sequence homology. Using co-immunoprecipitation, we revealed that FTT-2 formed a complex with GFP-fused DAF-16 in C. elegans. Our results indicate that FTT-2 binds to DAF-16 in C. elegans and regulates DAF-16 by sequestering it in the cytoplasm. A similar mechanism of regulation of FOXO by 14-3-3zeta has been reported in mammalian cells, highlighting the high degree of conservation of the daf-2/insulin-like signaling pathway.
Li
Ji
J
Department of Molecular Biology, Cornell University, Ithaca, NY 14850, USA.
Tewari
Muneesh
M
Vidal
Marc
M
Lee
Siu Sylvia
SS
D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017931:DNA Primers; D051858:Forkhead Transcription Factors; D018507:Gene Expression Regulation, Developmental; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D051858:Forkhead Transcription Factors; D014157:Transcription Factors; C108831:daf-16 protein, C elegans; C106207:par-5 protein, C elegans