Selection of candidate genes for differences in fat metabolism between cattle subcutaneous and perirenal adipose tissue based on RNA-seq

The site of fat deposition plays an important role in meat quality and body health. Biologically, the perirenal visceral fat (PF) and back subcutaneous fat (BF) are distinct. Angus and Simmental cattle (Bos taurus) were used as models. HE staining, triglyceride assay kit and RNA-seq were used to analyze the differences in tissue morphology and lipid accumulation, co-genes, and differentially expressed genes (DEGs) between the two tissues. According to the findings, BF has a smaller cell area and greater lipid deposition ability than PF. RNA-seq generated approximately 10.99 Gb of data in each library, and 23,472 genes were identified. The genes FABP4, ADIRF, and SCD that are related to adipose deposition were highly expressed in four tissues. There were 1678 DEGs and 1955 DEGs between BF and PF in Angus and Simmental cattle respectively. Gene Ontology function analysis identified several DEGs involved in metabolism. KEGG pathway analysis showed that four pathways related to fat metabolism were enriched. In the BF, seven genes (COL1A1, COL1A2, COL3A1, COL2A1, RXRA, C1QTNF7, and MOGAT2) were up-regulated. Five genes (ADRB3, ABHD5, CPT1B, CD36, LPIN1) were down-regulated. This study identified candidate genes that led to differences in fat metabolism, which could be useful in cattle breeding.

脂肪沉积的位点对肉质与机体健康具有重要调控作用。从生物学特性来看，肾周内脏脂肪（perirenal visceral fat, PF）与背部皮下脂肪（back subcutaneous fat, BF）存在显著分化。本研究以安格斯牛和西门塔尔牛（Bos taurus）为实验动物模型。采用HE染色法、甘油三酯检测试剂盒以及RNA测序（RNA-seq）技术，系统分析了两种脂肪组织在组织形态、脂质积累能力、共表达基因及差异表达基因（differentially expressed genes, DEGs）层面的差异。研究结果表明，背部皮下脂肪的细胞面积小于肾周内脏脂肪，且脂质沉积能力更强。RNA-seq测序每个文库可产出约10.99 Gb的数据，共鉴定得到23472个基因。与脂肪沉积相关的FABP4、ADIRF及SCD基因在四种实验组织中均呈现高表达水平。安格斯牛与西门塔尔牛的背部皮下脂肪和肾周内脏脂肪之间，分别存在1678个和1955个差异表达基因。基因本体（Gene Ontology, GO）功能分析发现，多个差异表达基因参与代谢相关生物学过程。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路分析显示，四条与脂肪代谢密切相关的通路被富集。在背部皮下脂肪组织中，COL1A1、COL1A2、COL3A1、COL2A1、RXRA、C1QTNF7及MOGAT2共7个基因呈上调表达；ADRB3、ABHD5、CPT1B、CD36及LPIN1共5个基因呈下调表达。本研究鉴定得到了介导脂肪代谢差异的候选基因，可为肉牛育种工作提供理论参考。