Nematodes expressing a SBP-1TGFP fusion protein driven by the sbp-1
promoter exhibit strong nuclear fluorescence in the intestinal cells of fed animals, whereas fasted animals show markedly reduced nuclear SBP-1TGFP levels, consistent with previously published results in mammals. In contrast, nuclear SBP-1TGFP expression remains high in fasted nematodes carrying a deletion in sir-2.1
, or in animals treated with the sirtuin inhibitors nicotinamide and sirtinol. Transcript levels of sbp-1
are only very modestly altered by feeding/fasting or loss of sir-2.1
, suggesting that SIR-2.1 mediates fasting-dependent regulation of SBP-1 protein levels by a post-transcriptional mechanism.