title: Effect of diacylglycerol acyltransferase 2 overexpression in 3T3-L1 is associated to an increase in mono-unsaturated fatty acid accumulation.
abstract: BACKGROUND
  Fatty 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.
  
  
  METHODS
  To 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 (13)C 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.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  In 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.
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Zhiqi
authors: Z
authors: Zhang
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Gang
authors: G
authors: Shu
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Xiaotong
authors: X
authors: Zhu
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Junming
authors: J
authors: Guo
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Han
authors: H
authors: Cai
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Songbo
authors: S
authors: Wang
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Lina
authors: L
authors: Wang
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Ping
authors: P
authors: Gao
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Qianyun
authors: Q
authors: Xi
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Yongliang
authors: Y
authors: Zhang
authors: College of life science, Xiamen University, Fujian province, Xiamen 361005, China.
authors: Li
authors: L
authors: Yuan
authors: ALLTECH-SCAU Animal Nutrition Control Research Alliance, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
authors: Qingyan
authors: Q
authors: Jiang
keywords: DGAT2; Fatty acid composition; Overexpressing; Pig