Table 1. Expression of signal-transduction genes in C. elegans strains, assessed by real-time polymerase chain reaction.
| Pathway | Gene | Protein Function / Notes | DAF-16 sites† | hx546 | daf-16; hx546 | F1mg44 | F2 mg44 | daf-16; mg44 | dauers |
| Insulin/IGF-1 Signaling (IIS) pathway | |||||||||
| ins-1 | DAF-2/IIS antagonist | 1, 1 | 16.0* | 4.0 | − | 10.0*** | 3.5° | 80.0**** | |
| ins-5 | neuronal expression; no effect of RNAi | 1, 3 | 1.9 | 0.90 | 24.0** | 4.5* | 1.0 | 7.4* | |
| ins-6 | poss. agonist; no effect of RNAi | 0, 2 | 1.9 | 1.4 | 10.7** | 3.2* | 1.2 | 2.2 | |
| ins-7 | DAF-2/IIS agonist; RNAi extends life | 0, 2 | 5.3* | 5.3* | 0.95 | 0.55° | 1.2 | 1.6 | |
| ins-14 | possible DAF-2 / IIS agonist | 0. 0 | 1.5 | 1.1 | 26.7* | 6.8**** | 1.8* | 22.0***** | |
| ins-18 | IIS antagonist; structure similar to INS-1 | 1, 1 | 1.4 | 1.5 | 3.0° | 5.0*** | 1.1 | 16.1**** | |
| daf-2 | insulin/IGF-1 receptor | 1, 2 | 0.38° | 0.90 | 1.6° | 0.20***** | 0.19***** | 0.55° | |
| ist-1 | insulin-receptor substrate 1 (IRS-1) | 3, 0 | 2.0 | 0.55 | 1.3° | 1.8* | 0.90 | 6.5 | |
| age-1 | PI3Kcs (class-I) | 0, 0 | 1.6 | 0.80 | 0.06*** | 0.07***** | 0.63 | 0.17** | |
| F39B1.1 | PI3Kcs (class-II) | − | 0.90 | 0.80 | 0.90 | 0.25*** | 0.90 | 0.90 | |
| vps-34 | PI3Kcs (class-III); vesicular trafficking | 0, 2 | 1.7 | 0.90 | 0.90 | 0.37** | 1.0 | 0.44 | |
| daf-18/pten | PIP3 phosphatase (opposes AGE-1) | 0, 0 | 1.8 | 1.0 | 0.35° | 0.08***** | 1.0 | 0.03***** | |
| sgk-1 | serum/glucocorticoid-dependent kinase 1 | − | 1.0 | 0.80 | 0.18* | 0.25** | 0.85 | 0.15* | |
| pdk-1 | phosphoinositide-dependent kinase 1 | 2, 1 | 0.44 | 0.63 | 1.4 | 0.18** | 0.52° | 0.50° | |
| akt-1 | ortholog of S/T kinase AKT/PKB (RAC-α) | 3, 1 | 1.0 | 1.0 | 1.3 | 0.60 | 1.2 | 0.46° | |
| akt-2 | homolog of S/T kinase AKT/PKB (RAC-γ) | − | 1.90 | 0.64 | 5.2° | 2.6° | 0.50 | 3.2 | |
| daf-16 | FOXO1 / FOXO3 forkhead transcr'n factor | 3, 3 | 0.90 | 0.40 | 0.70 | 0.60° | 0.50° | 1.0 | |
| sod-3 | Mn-superoxide dismutase (mitoch. SOD) | − | 0.57 | 0.55 | 3.0° | 9.0*** | 0.90 | 7.0* | |
| pepck | phosphoenolpyruvate carboxykinase | 0, 1 | 0.90 | 1.1 | 0.80 | 8.5* | 0.95 | 0.90 | |
| DAF-16-interacting transcriptional regulators | |||||||||
| cst-1 | DAF-16 kinase, responds to oxidat.-stress | 0, 0 | 2.3 | 0.90 | 1.3 | 1.0 | 1.2 | 2.6° | |
| bar-1 | β-catenin transcript'n factor (Wnt pathway) | 0, 3 | 0.60 | 1.1 | − | 0.60 | 0.70 | − | |
| smk-1 | transcr'l coactivator of DAF-16 and PHA-4 | 1, 3 | 0.72 | 1.1 | 0.70 | 0.28** | 0.87 | 0.18*** | |
| par-5 | 14-3-3 family; sequesters pDAF-16 | 1, 3 | 1.5 | 1.1 | 0.48 | 0.28** | 1.1 | 0.13*** | |
| ftt-2 | 14-3-3 family; sequesters pDAF-16 | − | 1.5 | 0.90 | 0.62 | 0.86 | 1.0 | 0.63 | |
| sir-2.1 | transcriptional coactivator of DAF-16 | 0, 1 | 0.91 | 1.1 | 0.95 | 0.26** | 0.89 | 0.29** | |
| TGF-β signaling | |||||||||
| daf-7 | TGF-β family member (ligand, agonist) | − | 7.0* | 2.6 | 3.0 | 5.3** | 1.2 | 19.7** | |
| daf-1 | TGF-β family receptor type I | 1, 0 | 2.2° | 1.5° | 0.50° | 0.22***** | 1.6 | 1.1 | |
| daf-4 | TGF-β family receptor type II | 1, 3 | 1.5 | 1.0 | 0.60 | 0.24*** | 1.5 | 1.2 | |
| daf-12 | VDR homolog, controlled by TGF-β, IIS | − | 1.6 | 1.0 | 0.70 | 1.6 | 0.80 | 3.1° | |
| daf-3 | SMAD transcription factor | 2, 1 | 1.5° | 0.90 | 0.30*** | 0.30** | 1.9** | 1.7* | |
| ▸ TGF-beta signaling outputs to p38 and ERK MAPK pathways | |||||||||
| AMPK/TOR pathway (nutrient sensing) | |||||||||
| aak-1 | AMP-dependent kinase 1 | 2, 1 | 1.2 | 0.80 | 0.47 | 0.17*** | 1.0 | 0.05* | |
| aak-2 | AMP-dep't. kinase 2 (activates DAF-16) | − | 1.7° | 1.5* | 0.60** | 2.2** | 0.57 | 6.4* | |
| let-363 | FRAP/mTOR ortholog; part of PIK family | 1, 0 | 0.70 | 0.70 | 1.0 | 0.25** | 0.60 | 0.47 | |
| daf-15 | ortholog of RAPTOR, mTOR reg. subunit | 2, 0 | 0.80 | 0.90 | 0.80 | 0.15*** | 0.80 | 0.22** | |
| rsks-1 | S6K; ribosomal S6 protein kinase 1 | 1, 0 | 1.6 | 0.90 | 1.0 | 1.5 | 1.2 | 3.9* | |
| p38-MAPK (stress response, immune response) | |||||||||
| pmk-1 | p38 MAPK 1 (mitogen activated prot. kinase) | 3, 0 | − | 1.0 | 3.8° | 0.60 | 0.70 | 1.0 | |
| pmk-2 | p38 MAPK 2 (mitogen activated prot. kinase) | 2, 0 | − | 0.20* | 0.40 | 0.20* | 0.18* | 0.50 | |
| pmk-3 | p38 MAPK 3 (mitogen activated prot. kinase) | 2, 0 | − | 0.40 | 1.2 | 0.56 | 0.20* | 1.5 | |
| atf-2 | cAMP-dep. transcription factor family (+) | 0, 1 | 2.5 | 1.1 | 44.1*** | 3.9* | 2.6° | 9.6** | |
| ▸ p38 MAPK signaling also activates DAF-3 | |||||||||
| JNK-MAPK (immune signaling, stress response) | |||||||||
| jnk-1 | Jun N-terminal kinase 1 | 0, 0 | 1.2 | 1.4 | 0.95 | 3.5*** | 1.2 | 13.2***** | |
| jun-1 | JUN subunit, AP-1 transcription factor (+) | 2, 2 | 0.74 | 1.0 | 1.1 | 0.6° | 0.95 | 2.2* | |
| ▸ JNK signaling also converges on DAF-3 and DAF-16/FOXO | |||||||||
| ERK-MAPK (growth-factor and immune responses) | |||||||||
| let-60 RAS | small membrane GTPase co-receptor | 0, 0 | 0.50 | 0.30 | 0.18* | 0.16*** | 0.50 | 0.30 | |
| lin-45 | Ser/Thr kinase of MEK-2, activ by LET-60 | 0, 1 | 1.0 | 0.80 | 1.1 | 0.20** | 0.90 | 0.33** | |
| mek-1 | stress-response ERK for JNK-1, MPK-1 | 3, 1 | 0.75 | 0.50 | 0.30* | 0.23***** | 0.38° | 0.07**** | |
| mpk-1 | MAPK, transduces develop'l RAS signals | 0, 2 | 0.80 | 1.8 | 2.1 | 0.23* | 1.0 | 0.21* | |
| gsk-3 | glycogen-synthase kinase 3 | 0, 0 | 0.56 | 0.50 | 0.28° | 0.20** | 0.90 | 0.13* | |
| skn-1 | oxid.-damage-response TF, inhib'd by IIS | 0, 0 | 1.3 | 1.0 | 0.55 | 0.30* | 1.6 | 0.60 | |
Key: −, not assessed. Significance of difference from N2DRM (by 2-tailed t -test): °, nominally significant at P<0.05.
*, P<0.01; **, P<0.001; ***, P<1E−4; ****, P<1E−5, *****, P<1E−6.
†: Number of exact consensus DAF-16 sites in upstream 5-kb span, (a, b), where a = GTAAA(C/A)AA, and b = CTTATCA.
For each gene tested, wild-type N2DRM adults are compared to four age-1 mutant populations and to dauer larvae. The age-1(mg44) worms are F1 homozygotes at days 8–9 of adulthood, by which time they were post-gravid, or F2 homozygotes at day 10 (18 days post-hatch); other groups (N2DRM, age-1(hx546), and daf-16(mu86); age-1(mg44) double mutants) were harvested when post-gravid (days 6–8 of adulthood), or as dauer larvae (N2DRM only) from starved, dense cultures 1 day after >98% of worms had become resistant to lysis by 1% sodium dodecyl sulfate. Transcript levels were assayed for 3–8 independent biological replicates, with two cDNA syntheses and RT-PCRs for each. Numbers shown are transcript ratios for each group indicated (in the column header) relative to transcript levels of the same genes in near-isogenic N2DRM controls. All C(t) data (threshold cycle numbers) were normalized to the mean values for three control genes (β-actin, T08G5.3, and Y71D11.3) that did not change among the strains/groups tested. Changes that were at least nominally significant (P<0.05) are emphasized with bold font.