Eicosapentaenoic Acid Potentiates Brown Thermogenesis through FFAR4-dependent Up-regulation of miR-30b and miR-378

Abstract

Emerging evidence suggests that n-3 polyunsaturated fatty acids (PUFA) promote brown adipose tissue thermogenesis. However, the underlying mechanisms remain elusive. Here, we hypothesize that n-3 PUFA promotes brown adipogenesis by modulating miRNAs. To test this hypothesis, murine brown preadipocytes were induced to differentiate the fatty acids of palmitic, oleate, or eicosapentaenoic acid (EPA). The increases of brown-specific signature genes and oxygen consumption rate by EPA were concurrent with up-regulation of miR-30b and 378 but not by oleate or palmitic acid. Next, we hypothesize that free fatty acid receptor 4 (Ffar4), a functional receptor for n-3 PUFA, modulates miR-30b and 378. Treatment of Ffar4 agonist (GW9508) recapitulated the thermogenic activation of EPA by increasing oxygen consumption rate, brown-specific marker genes, and miR-30b and 378, which were abrogated in Ffar4-silenced cells. Intriguingly, addition of the miR-30b mimic was unable to restore EPA-induced Ucp1 expression in Ffar4-depleted cells, implicating that Ffar4 signaling activity is required for up-regulating the brown adipogenic program. Moreover, blockage of miR-30b or 378 by locked nucleic acid inhibitors significantly attenuated Ffar4 as well as brown-specific signature gene expression, suggesting the signaling interplay between Ffar4 and miR-30b/378. The association between miR-30b/378 and brown thermogenesis was also confirmed in fish oil-fed C57/BL6 mice. Interestingly, the Ffar4 agonism-mediated signaling axis of Ffar4-miR-30b/378-Ucp1 was linked with an elevation of cAMP in brown adipocytes, similar to cold-exposed or fish oil-fed brown fat. Taken together, our work identifies a novel function of Ffar4 in modulating brown adipogenesis partly through a mechanism involving cAMP activation and upregulation of miR-30b and miR-378.There are two specific types of fat with opposite functions, brown adipose tissue (BAT) 3 and white adipose tissue (WAT).WAT stores energy in the form of triglyceride, whereas BAT dissipates energy in the form of heat via uncoupling protein 1 (UCP1) (1). Recent advances in our understanding of BAT biology in humans have provided a new insight into weight loss strategies by boosting BAT thermogenesis. Despite the surge of research for identifying cellular and molecular regulators of brown fat development (2, 3), the role of dietary constituents, particularly dietary fatty acids (FA), in thermogenic activation is poorly understood. Depending on the degree of desaturation and the n-6/n-3 ratio, FA differentially control adiposity, insulin sensitivity, immune response (4), and probably energy expenditure (5-7). Lately, it has been suggested that n-3 polyunsaturated FA (PUFA) stimulate beige/brown adipogenesis in primary murine adipogenic precursor cells (5) as well as C57BL/6 mice (6, 7). The latter animal study suggests that n-3 PUFA are associated with sympathetic activation and increased ␤3-adrenergic receptor (Adrb3) signaling (7). However, the underlying mechanistic details of how dietary n-3 PUFA...

Transcriptomic and microRNA analyses of gene networks regulated by eicosapentaenoic acid in brown adipose tissue of diet-induced obese mice

“…However, it was not listed in the differentially expressed genes in the tables above, due to the higher cut off used in our data analyses. These findings are consistent with a recent report demonstrating that Ffar4 was a functional receptor for omega 3 fatty acids in mouse BAT [51]. …”

Inhibitory Effects of Toll-Like Receptor 4, NLRP3 Inflammasome, and Interleukin-1β on White Adipocyte Browning

“…To determine mitochondrial respiration, oxygen consumption rate (OCR) was measured using an XF24 Extracellular Flux analyzer (Seahorse) as we described previously [19]. Measurements were performed at the basal level and after injection of three compounds affecting bioenergetics: 1 µM Oligomycin (oligo) (Sigma), 2 µM carbonyl cyanide 4-trifluoromethoxy phenylhydrazone (FCCP) (Sigma), and 0.5 µM Antimycin A plus Rotenone (AA+Rot) (Sigma).…”

Divergent Response of Murine and Porcine Adipocytes to Stimulation of Browning Genes by 18‐Carbon Polyunsaturated Fatty Acids and Beta‐Receptor Agonists

“…Therefore, several recent studies have been conducted to investigate effects of various dietary bioactive compounds for their potential to activate inducible brown‐like phenotype in white adipocytes. PUFA is reported as one of the effective stimuli to promote thermogenic capacity of adipocytes (Fleckenstein‐Elsen et al, ; Kim et al, ; Matsuo et al, ; Takahashi et al, ). However, there are no studies in which effects of different fatty acids with the same chain length on beige adipocyte activation in multiple adipocyte model has been studied.…”