Fig. 2

Schematic of the IGF/AKT/FOXO pathway in fruitfly (A), amphioxus (B), and mammals (C), and expression of FOXO-regulated genes in amphioxus (E). Insulin/IGF bind to their receptors, and IRS recruits Pi3K class I or III complexes to the membrane. Pi3K converts PIP₂ to PIP₃, which activates PDK, which phosphorylates AKT, which phosphorylates FOXO, inactivating it by preventing its entry to the nucleus. Without insulin, FOXO is not phosphorylated, and it can activate its target genes, including for example, Atrogin-1 (ULK family in chordates). D Key to gene names for protein subunits of Pi3K complex in mammals. E Proportion of overall normalised (by variance stabilisation in DESeq2) number of reads detected in each experimental condition for genes regulated by FOXO involved in autophagy [136]. Statistically significant differences in expression (p < 0.05, DESeq2 DGE analysis) are denoted by asterisks and brackets. Total number of reads are FOXO: 17,117; TRIM55: 297,158; LGMN: 71,123; PINK1: 226,008; MAP1LC3a: 5612; MAP1LC3c: 1049; ULK2: 25,482; FBXO30: 3212. Gene names reflect BLAST annotation and may not represent direct orthology. BL– numbers are B. lanceolatum gene model IDs. Error bars are the standard deviation of the mean across the four samples in each condition