Mono-unsaturated fatty acids link H3K4me3 modifiers to C. elegans lifespan

Chromatin and metabolic states both influence lifespan, but how they interact in lifespan regulation is largely unknown. The COMPASS chromatin complex, which trimethylates lysine 4 on histone H3 (H3K4me3), regulates lifespan in C. elegans. However, the mechanism by which H3K4me3 modifiers impact longevity, and whether it involves metabolic changes, remain unclear. Here we find that H3K4me3-methyltransferase deficiency, which extends lifespan, promotes fat accumulation with a specific enrichment of mono-unsaturated fatty acids (MUFAs). This fat metabolism switch in H3K4me3-methyltransferase deficient animals is mediated at least in part by downregulation of germline targets, including S6 kinase, and by activation of an intestinal transcriptional network that upregulates delta-9 fatty acid desaturases. Interestingly, MUFA accumulation is necessary for the lifespan extension of H3K4me3-methyltransferase deficient worms, and dietary MUFAs are sufficient to extend lifespan. Given the conservation of lipid metabolism, dietary or endogenous MUFAs could extend lifespan and healthspan in other species, including mammals.