Fatty Acid Elongase 7 (ELOVL7) Plays a Role in the Synthesis of Long-Chain Unsaturated Fatty Acids in Goat Mammary Epithelial Cells.

Shi Shi,Loor Loor,Luo Luo,Wang Wang,Liu Liu

doi:10.3390/ani9060389

Abstract

Simple SummaryVery-long-chain elongases are required for the synthesis of essential fatty acids in non-ruminants. Whether the fatty acid elongase 7 (ELOVL7) plays a role in ruminants is unclear. We demonstrated, in goat mammary epithelial cells, that ELOVL7 activation resulted in greater concentrations of vaccenic (C18:1n7) and linoleic (C18:2) acid, and lower concentrations of palmitoleic (C16:1n7) and oleic (C18:1n9) acid. Knockdown of ELOVL7 increased the concentration of C18:1n9. The data support a novel role of ELOVL7 in altering long-chain unsaturated fatty acids in goat mammary epithelial cells. In humans, fatty acid elongase 7 (ELOVL7) plays a role in synthesis of long-chain saturated fatty acids. Whether ELOVL7 protein plays a role in ruminants is unclear. The transcript abundance of ELOVL7 in goat mammary tissue was assessed at three stages of lactation. Results showed that ELOVL7 had the highest expression in the dry period compared with peak and late lactation period. Results revealed that ELOVL7 overexpression was correlated with lower expression in diacylglycerol O-acyltransferase 2 (DGAT2) and stearoyl-CoA desaturase 1 (SCD1), and had no significant effect on triacylglycerol concentration. Overexpression of ELOVL7 significantly decreased the concentration of palmitoleic (C16:1n7) and oleic (C18:1n9) acid, and increased the concentration of vaccenic (C18:1n7) and linoleic (C18:2) acid. Overexpression of ELOVL7 significantly upregulated the elongation index of C16:1 in goat epithelial mammary cells (GMEC), but had a minor effect on that of palmitate (C16:0). Knockdown of ELOVL7 decreased mRNA expression of fatty acid binding protein 3 (FABP3) and fatty acid desaturase 2 (FADS2) and had a minor effect on triacylglycerol concentration; however, it increased concentration of C18:1n9 in GMEC. The elongation indices of C16:0 and C16:1 did not differ due to knockdown of ELOVL7. The minor change for the C16:0 and stearate (C18:0) was observed after activation of ELOVL7, suggesting the two fatty acids are not the preferential substrates of ELOVL7 in cultured GMEC. However, changes in C18:1n9 and C18:2 after overexpression or knockdown of ELOVL7 indicated a biological functional role of ELOVL7. Collectively, our data highlighted a role of ELOVL7 in long-chain unsaturated fatty acid elongation in goat mammary epithelial cells.

Highlights

Milk fat is an important energy source in terms of dairy production
The present study delivers new information since we studied long-chain fatty acids (LCFAs) composition and selective regulation of gene expression by switching ELOVL7 expression in Goat mammary epithelial cells (GMEC) culture
The alteration of C16:1 in the present study indicated that ELOVL7 may act to control the synthesis of LCFA in GMEC

Summary

Introduction

Milk fat is an important energy source in terms of dairy production. About half of the milk fats are synthesized de novo [1]. The de novo synthesis of fatty acids (FAs) involves many enzymes containing acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN). FAs come from diet and adipose tissue mobilization [1]. FA elongases and desaturases cooperate to synthesize monounsaturated or polyunsaturated fatty acids [2,3]. It is well investigated that the FA desaturase enzymes (e.g., stearoyl-CoA desaturase 1 (SCD1)) catalyze the conversion of saturated

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