Figure 1.

Fat metabolites mediate important cellular functions in response to environmental changes. (A) Roles of lipase-mediated fat metabolism and AA supplements on life span extension under fed and fasting conditions, based on O'Rourke et al. (2013). Dietary restriction promotes expression of LIPL-4 and possibly other lipases that hydrolyze fat or other lipids, which in turn results in the enrichment of certain ω-3 and ω-6 PUFAs (EPA and AA, respectively). High level of AA, but not EPA, induces autophagy and promotes longevity. Although LIPL-4 was predicted to be a TAG lipase, it is possible that its major substrates include other lipids, such as phospholipids that could be involved in the fasting response pathway. (B) A generalized model illustrating the impact of fat/TAG metabolism on cellular processes and animal health. (X) Factors, such as lipases, that play critical roles in regulating fat metabolism and FA homeostasis in response to environmental changes or other signals.