1650-P: Characterizing the Mechanism of Action of the Lipokine 12,13-diHOME

Lipids play an essential role in physiology. In addition to serving as an energy source, bioactive lipids, also known as lipokines, function as signaling molecules regulating metabolism and inflammation. A major source of lipokines, brown adipose tissue (BAT) has been shown to have beneficial effects on cardiometabolic health by increasing energy expenditure and improving glucose tolerance, thus providing a potential target for therapeutic interventions. Recent studies have identified 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME, produced by cytochrome P450-epoxide hydrolase metabolism of linoleic acid (C18:2n-6), as a lipokine produced by BAT that modulates fatty acid uptake (FAU) into brown adipocytes and skeletal muscle cells in response to cold stimulation or exercising, respectively. Here, we characterized the molecular mechanism and structure-activity relationship (SAR) of 12,13-diHOME in BAT fatty acid uptake. Conversion of the terminal carboxylic acid of 12,13-diHOME to ethyl acetate and changes in saturation results in decreased stimulated FAU indicating 12,13-diHOME's activity is structurally dependent. In addition, we provide insight into a novel protein target responsible for enhancing FAU in BAT, in part, by enhancing intracellular calcium mobilization and influencing the expression of lipolytic genes. Furthermore, we have determined that the 12,13-diHOME-stimulated FAU is, in part, dependent on Gq-mediated calcium mobilization as determined by the utilization of Gq inhibitor YM-254890. Thus, the receptor of 12,13-diHOME could represent a target to augment BAT activity by modulating fatty acid metabolism, which could contribute to increased energy expenditure and, consequently, to the prevention of cardiometabolic diseases. Disclosure J.I.Senfeld: None. M.Lynes: None. S.Kodani: None. K.Lee: None. Y.Tseng: Consultant; Cellarity, LyGenesis.