Abstract
BackgroundFatty acid (FA) composition is the most important parameter affecting the flavor and nutritional value of the meat. The final and the only committed step in the biosynthesis of triglycerides is catalyzed by diacylglycerol acyltransferase 2 (DGAT2). The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes, However, little is known about the effect of DGAT2 on the FA composition of these cells.MethodsTo investigate the role of DGAT2 in regulating lipid accumulation, FA composition and the expression of adipogenic genes, we cloned the open reading frame of the porcine DGAT2 gene and established 3T3-L1 cells that overexpressed DGAT2. Cells were then cultured in differentiation medium (DM) without FA, with a mixture of FAs (FA-DM), or containing a 13C stable isotope-labeled FA mixture (IFA-DM). The FA composition of adipocytes was analyzed by gas chromatography–mass spectrometry and gas chromatography-isotope ratio mass spectrometry. Quantitative PCR and western blotting were employed to detect expression of adipogenic genes in 3T3-L1 adipocytes cultured with FA-DM for 12 d.ResultsThe triacylglyceride (TAG) content was significantly higher in 3T3-L1 adipocytes overexpressing DGAT2 than in control cells. When cultured in DM or FA-DM for 12 d, cells overexpressing DGAT2 showed a higher proportion of unsaturated FAs (C16:1 and C18:1). However, when cells overexpressing DGAT2 were cultured with FA-DM for 30 min, the FA composition was almost identical to that of controls. Further, the proportion of stable isotope-labeled FAs were similar in 3T3-L1 adipocytes overexpressing DGAT2 and control cells cultured in IFA-DM for 12 d. These results collectively indicate that the higher proportion of mono-unsaturated FAs, C16:1 and C18:1, may originate from de novo FA synthesis but not from the uptake of specific FAs from the medium. This hypothesis is further supported by evidence that both mRNA and protein expression of genes involved in FA synthesis (ACACA, FASN, SCD1, and A-FABP) were significantly higher in cells overexpressing DGAT2 than in control cells.ConclusionsIn conclusion, our study revealed that TAG accumulation, the proportion of MUFAs, and the expression of adipogenic genes were higher in 3T3-L1 cells overexpressing DGAT2 than in control cells.
Highlights
Meat quality depends on various sensory and chemical parameters, including color, tenderness, and the content of flavoring substances [1]
Lipid accumulation in 3T3-L1 adipocytes overexpressing diacylglycerol acyltransferase 2 (DGAT2) 3T3-L1 cells transfected with pcDNA3.1(+)-DGAT2 had 63-fold higher DGAT2 mRNA expression than control cells transfected with empty vector (P < 0.01) (Figure 1)
Our study revealed that TAG accumulation, the proportion of monounsaturated FAs (MUFAs), and the expression of adipogenic genes were all higher in 3T3-L1 cells overexpressing DGAT2 than in control cells
Summary
Meat quality depends on various sensory and chemical parameters, including color, tenderness, and the content of flavoring substances [1]. Fatty acid (FA) composition is one of the most important parameters affecting meat quality. The proportion of saturated, monounsaturated, and polyunsaturated FAs in the diet is reported to have important effects on human health. Diacylglycerol acyltransferase (DGAT1 and DGAT2) catalyzes the final step in triacylglyceride (TAG) formation through the acylation of diacylglycerol (DAG) [14,15]. In COS-7 cells, DGAT2 overexpression has been reported to significantly increase lipid accumulation [17]. The effect of DGAT2 overexpression on the FA composition of cells is unknown. Fatty acid (FA) composition is the most important parameter affecting the flavor and nutritional value of the meat. The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes, little is known about the effect of DGAT2 on the FA composition of these cells
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