Forkhead box protein O (FOXO) transcription factor (DAF-16 ortholog in *Caenorhabditis elegans*) (DAF-16/FOXO)

Forkhead box protein O (FOXO) transcription factors, with DAF-16 as the C. elegans ortholog, are evolutionarily conserved regulators of gene expression that govern stress resistance, metabolism, and longevity[1][2][3][5]. In C. elegans, DAF-16 is the sole FOXO ortholog and the principal downstream effector of the insulin/IGF signaling pathway. When conditions such as food deprivation, heat, or oxidative stress occur, or when insulin/IGF signaling is low, DAF-16 translocates into the nucleus and activates (or represses) specific downstream genes that promote survival, stress resistance, and extended lifespan[1][2][3][4][5]. DAF-16/FOXO activity is regulated by phosphorylation (primarily by AKT), which retains it in the cytoplasm under normal conditions, and by interactions with cofactors such as 14-3-3 proteins, SMK-1/SMEK-1, and HLH-30/TFEB, which modulate its transcriptional output to different cellular threats and developmental cues[2][3][5]. In mammals, the FOXO family comprises multiple paralogs (FOXO1, 3, 4, and 6), which participate in similar pathways affecting cell survival, metabolism, and tumor suppression[2][5]. DAF-16/FOXO represents a central node connecting environmental, hormonal, and developmental signals to gene expression programs ensuring organismal adaptation and longevity[1][2][3][5].

Other names

DAF-16FOXO transcription factor (in invertebrates DAF-16, in mammals FOXO1, FOXO3, FOXO4, FOXO6)Forkhead box O

Activation or inhibition of the insulin/IGF signaling pathway alters DAF-16/FOXO nuclear translocation and transcriptional activity[1][2][3][5]; Post-translational modification (e.g., phosphorylation by AKT, MST1, or sequestration by 14-3-3 proteins) regulates its cellular localization and activity[1][2][3][4]