Myostatin Alteration in Pigs Enhances the Deposition of Long-Chain Unsaturated Fatty Acids in Subcutaneous Fat

Abstract

In animals, myostatin (MSTN) is a negative regulator that inhibits muscle growth and repair. The decreased level of functional MSTN gene expression can change the amount and proportions of fats in pigs. In this study we determined the lipidomics of subcutaneous fat in MSTN single copy mutant pigs and evaluated the variations in lipid contents of the subcutaneous fat from MSTN^+/- and wild type Large White (LW) pigs via ultra-performance liquid chromatography-quadrupole/Orbitrap-mass spectrometry (MS). The results showed that the quantities of glycerolipids, sphingolipids, fatty acyls and glycerophospholipids were significantly changed, particularly, the molecular diacylglycerol in glycerolipids, long-chain unsaturated fatty acids, and ceramide non-hydroxy fatty acid-sphingosine in sphingolipids were remarkably increased in the MSTN^+/- group. Due to their positive bioavailability demonstrated by previous researches, these three lipids might be beneficial for human health. Further, the results of our study confirm that MSTN participates in the regulation of fat metabolism, and reduced expression of MSTN can ultimately influence the accumulation of lipid contents in the subcutaneous fat of pigs.

Keywords: glycerolipids; glycerophospholipids; lipidomics; long-chain unsaturated fatty acids; myostatin; pigs; sphingolipids; subcutaneous fat.

Figure 1

The decreased expression of MSTN altered the lipid content of subcutaneous fat. (a) HE staining of adipose tissue from MSTN^+/− pigs; (b) HE staining of adipose tissue from WT pigs; (c) Volcano plot of lipid metabolites in positive ion mode; (d) Volcano plot of lipid metabolites in negative ion mode.

Figure 2

PCA scores of the detected compounds in the two groups. (a) PCA scatter plot of differentially expressed lipid metabolites in positive ion mode; (b) PCA scatter plot of differentially expressed lipid metabolites in negative ion mode.

Figure 3

PLS-DA of lipid metabolite profiling data for comparison of MSTN^+/− and WT pigs. (a) PLS-DA score plots of WT and MSTN-edited pigs based on the extracted spectral data in positive ion mode; (b) PLS-DA score plots of WT and MSTN-edited pigs based on extracted spectral data in negative ion mode; (c) Permutation plot of PLS-DA based on the extracted spectral data in positive ion mode. R²Y = 0.8931 and Q² = 0.6741; (d) Permutation plot of PLS-DA based on the extracted spectral data in negative ion mode. R²Y = 0.8130 and Q² = 0.7418.

Figure 4

Differentially expressed lipid metabolites in the MSTN^+/− versus the WT pigs. (a) Of the 44 differentially expressed metabolites, 43 were upregulated and 1 was downregulated; (b) The differential metabolites included 24 glycerolipids (GL), 14 sphingolipids (SP), 8 fatty acyls (FA), and 2 glycerophospholipids (GP). There were 22 diacylglycerol (DG) and 2 triacylglycerol (TG) molecules in the 24 differentially expressed glycerolipids. There were 13 ceramide non-hydroxy fatty acid-sphingosine (Cer[NS]) and 1 sphingomyelin (SM) in differential sphingolipids.

Figure 5

Differentially expressed long-chain unsaturated fatty acids in the MSTN^+/− versus the WT pigs. (a–h) Relative expression level of FA 18:1 (a), FA 18:2 (b), FA 18:3 (c), FA 20:2 (d), FA 20:3 (e), FA 20:4 (f), FA 22:4 (g), FA 22:5 (h) was significantly different between MSTN^+/− and WT pigs. Note: ** p < 0.01, *** p < 0.001.

Figure 6

Lipid metabolic pathway analysis of the identified differential lipid species. (The circle size and x-axis represent the pathway impact value, and the circle color and y-axis is the -log (p-value) obtained from pathway enrichment analysis. 1: pathway of biosynthesis of unsaturated fatty acids; 2: pathway of glycerophospholipid metabolism; 3: pathway of linoleic acid metabolism; 4: pathway of alpha-linolenic acid metabolism; 5: pathway of glycerolipid metabolism; 6: pathway of sphingolipid metabolism; 7: pathway of arachidonic acid metabolism.)