DAF-16, a FoxO homolog of nematode, induces an expression of fatty acid metabolic genes
fat-7 and
elo-2, resulting in the accumulation of fat storage. However, functional interaction among
daf-16, fatty acid metabolism and fat storage remains to be clarified. Recently, we clarified that introduction of
fat-2-RNAi and
fat-6-RNAi decreased fat accumulation of nematode. RNAi of
fat-2,
fat-6 and
elo-2 raised transcriptional activity of
daf-16, particularly, RNAi effect of
fat-2 which was oleic acid desaturase was remarkable. This result contradicts a past report that
daf-16 was associated with an increase of fat storage. Therefore we examined functional interaction of
daf-16 and fat storage. Induction of dauer formation at 25 degrees centigrade of
daf-2 mutant (
e1370) resulted in the increase of fat storage in L2 larva, and the decrease of fat storage in L4 larva. In
daf-16 deficit mutant (mgDF50), fat storage level which reduced by RNAi of
fat-2,
fat-7 and
elo-2, was restored to an equal level to N2-RNAi (-). Furthermore, transcriptional activity of
daf-16 was suppressed by addition of linoleic acid or alpha-linolenic acids to
fat-2 RNAi worm, and fat storage recovered at the same time. These results suggest that
daf-16 acted to an increase of fat storage in Dauer larva, and a suppression of fat storage in adult worm. In addition, functional interaction between
daf-16 and fatty acid metabolism may undergo some controls by possibly PUFA (Poly-unsaturated fatty acids).