Abstract
Castration is an important means of improving the beef quality via increasing fat deposition. However, little is known about the molecular mechanism underlying the fat deposition after castration. Here, the intramuscular fat (IMF) content of the steer group was shown to be much higher than the bull group. To understand transcriptional changes in the genes involved in fat deposition following castration, differential expression patterns of mRNAs in liver tissue were investigated in steers and bulls using RNA sequencing. In total, we obtained 58,282,367–54,918,002 uniquely mapped reads, which covered 90.13% of the currently annotated transcripts; 5,864 novel transcripts and optimized 9,088 known genes were determined. These results indicated that castration could change the expression patterns of mRNAs in liver tissue, and 282 differentially expressed genes (DEGs) were detected between steers and bulls. KEGG pathway analysis showed that the DEGs were mostly enriched in PPAR signaling pathway, steroid biosynthesis, steroid hormone biosynthesis, and biosynthesis of fatty acids. Furthermore, eight DEGs were corroborated via quantitative real-time PCR and we found that FABP1 gene knockdown in bovine hepatocytes prominently reduced intracellular triacylglycerol (TAG) synthesis and very low density lipoprotein (VLDL) secretion in culture medium. In summary, these results indicate that FABP1 may promote fat deposition by promoting the production and secretion of TAG and VLDL in steer liver.
Highlights
Castration is an important means of improving beef quality via increasing fat deposition, and raising prices at market compared with the carcasses from bulls [1,2,3,4]
The variation of the mRNA expression profiles caused by castration in liver tissue and its effects on fat deposition are still unrevealed in bovine
Previous studies have revealed that APOA1 and APOA2 genes were key regulatory factors of high density lipoprotein metabolism, which is significantly associated with obesity and body weight in humans [30]; APOA1 and APOA2 have been considered as candidate genes for back fat thickness in pigs [30]
Summary
Castration is an important means of improving beef quality via increasing fat deposition, and raising prices at market compared with the carcasses from bulls [1,2,3,4]. Castration has been proposed as a method in the beef industry improve beef quality, and the number of castrated male livestock is increasing due to their high market value [5]. Studies of the mechanisms and regulation of fat deposition after castration are limited. The major sites of lipogenesis are adipose tissue and the liver [6, 7], and recent studies have indicated that. FABP1 and steer fat deposition design, data collection and analysis, decision to publish, or preparation of the manuscript
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