Concurrent Supplementation of Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) Impairs Brown Adipogenesis and Thermogenic Capacity in C2C12 Myoblasts
Authors: Hemza Saeed , Baum Jamie , Huang Yan 
Published: June 2021

N−3 fatty acids are wildly used as dietary supplements during pregnancy due to their beneficial role in fetal neurodevelopment and infant birth weight. However, n−3 fatty acid supplementation can modulate the levels of critical proteins controlling inflammation, lipid metabolism, and energy utilization, which may affect fetal muscle cell differentiation and adipose deposition during gestation. Previously, we found EPA and DHA play a role in the commitment of C2C12 cells into the white‐like adipogenic lineage through blocking myotube formation and up‐regulation white adipocyte‐specific genes like BMP4 and CEBP/α, resulting in a reduction of oxygen consumption rate and accumulation of lipid droplets, however, its role in brown adipocyte formation and activity is not well defined. In this study, we focus on the in vitro synergetic effect of EPA and DHA supplemented in media on the adipogenic potential of C2C12 undergoing differentiation into brown adipocyte as it might represent a pathophysiological explanation for the intramuscular fat depots and associated insulin resistance that characterized many metabolic diseases. We demonstrated that the differentiation route of C2C12 into brown adipocytes was compromised and the acquisition of the phenotype was inhibited upon exposure to concomitant treatment with EPA and DHA. This effect is might be in part due to the down‐regulation of the expression of brown adipocyte‐specific genes in EPA and DHA treated cells compared to control cells, including UCP‐1 (61.9% ± 10.14% lower, P < 0.05), PGC1α (81.3% ± 15.20% lower, P < 0.05), and BMP‐7 (66.3% ± 8.33% lower, P < 0.05), genes associated with ETC function mainly the members of complex IV such as COX7a1 (87.9% ± 0.94% lower, P < 0.05), and ATP5J2 (46.0% ± 4.66% lower, P < 0.05), the main component of Complex V, and mitochondrial biogenesis related genes such as ERRa (54.7% ± 2.44% lower, P < 0.05) (Fig. 1). Additionally, we observed a strong correlation between EPA and DHA treatment and decreasing the level of some Krebs cycle and electron transport chain regulating proteins, the most important of them are ATP synthase sub‐unit alpha (46.0% ± 5.24% lower, P < 0.05) and beta (48.1% ± 2.97% lower, P < 0.05), citrate synthase (73.9% ± 7.13% lower, P < 0.05), succinate Co‐A (87.4% ± 7.34% lower, P < 0.05), aconitate hydratase (57.6% ± 5.88% lower, P < 0.05), cytochrome c (86.1% ± 13.88% lower, P < 0.05) (Fig. 2); as well as increased lipid droplets size and number (Fig. 3). Furthermore, Seahorse XF Cell Mito Stress Test showed decreased basal (19.89 ± 0.867 pmol/min (Con) vs 11.02 ± 1.735 pmol/min, P < 0.05) and spare (419.41 ± 20.801 pmol/min (Con) vs 192.39 ± 2.665 pmol/min, P < 0.05) respiratory capacity, less proton leak (11.84 ± 0.232 pmol/min (Con) vs 5.88 ± 1.730 pmol/min, P < 0.05), and less ATP production (8.05 ± 0.653 pmol/min (Con) vs 5.14 ± 0.156 pmol/min, P < 0.05) in EPA and DHA treated cells (Fig. 4). Given that, reduction of the thermogenic capacity of brown adipocytes, we propose that prenatal exposure to EPA and DHA might be an essential factor in the context of the development of potential long‐term obesity and type 2 diabetes in neonates.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.