哈萨克羊和藏绵羊尾部脂肪组织差异表达基因和可变剪接的鉴定与分析

Identification and Analysis of Differentially Expressed Genes and Alternative Splicing in Adipose Tissue from Tails between Kazak and Tibetan Sheep

为鉴定哈萨克羊和藏绵羊尾部脂肪组织的差异表达基因和可变剪接,分别提取6只(3公,3母)无亲缘关系的2岁成年哈萨克羊与藏绵羊尾部脂肪组织总RNA,构建2个高通量测序文库,利用TopHat2软件将短序列定位到绵羊参考基因组,采用cuffdiff软件分析基因表达丰度和差异表达基因。结果表明,共有19个基因在2个品种绵羊尾脂中的表达丰度均高于1 000FPKM,包括ADIPOQ、SPARC、VIM等。其中,2个品种尾部脂肪组织中表达量最高的转录本均定位于线粒体基因组5 331~14 154bp,该区域主要包含COX1、COX2、ATP8等基因,其表达丰度在哈萨克羊和藏绵羊中分别高达29 724.20和28 818.80FPKM。而FABP4则是表达丰度最高的核基因,在哈萨克羊和藏绵羊中的表达量分别为3 194.03和2 667.09。差异表达基因分析共鉴定出627个差异表达的基因,与藏绵羊尾部脂肪组织的表达量相比,哈萨克羊的尾部脂肪组织中共有221个上调基因和406个下调基因。其中,HBB基因表达量的变化倍数最大,下调约98倍。差异表达基因的富集分析结果表明,哈萨克羊尾脂中上调表达的基因主要参与脂肪酸代谢过程。另外,在2个品种尾脂中鉴定出11 870个可变剪接事件,其中383个为差异剪接事件。对相关差异表达基因和可变剪接的进一步研究将有助于揭示绵羊肥脂尾形成的分子机制。

This study aims to investigate the expression profiles and alternative splicing patterns of the genes expressed in the adipose from tails of Kazak （KS） and Tibetan （TS） sheep.Six two-year old unrelated adult individuals （three males and three females） for KS and TS breeds were randomly selected from a sheep farm located in Ningxia Autonomous Region,respectively.Total RNA from six sampled individuals of each breeds were extracted and mixed into a RNA-pool which was then used to construct the high-throughput sequencing library.A total of 19 genes showed high expression levels with more than 1 000 FPKM,such as ADIPOQ,SPARC,and VIM.The most abundantly expressed transcripts which mainly includedCOX1,COX2.TheATP8 was mapped to 5 331-14 154 bp of the mitochondrial genome in both breeds,and the expression abundance of this transcript were 29 724.20 and 28 818.80 FPKM in KS and TS,respectively.The expression levels of FABP4 most highly expressed nuclear gene were 3 194.03 FPKM in KS breeds and 2 667.09 in TS breeds,respectively.Comparing TS group with KS group,a total of 627 differentially expressed genes （DEGs） were identified,including 221 upregulated and 406 down-regulated genes.Notably,HBB showed largest down-regulation expression change in the fat tail of Kazak sheep.GO enrichment analysis revealed that the up-regulated expressed genes in KS sheep were significantly related with fatty acid metabolism processes.In addition,we detected a total of 11 870 alternative splicing events in the two breed samples,of which 383 splicing events were significantly discrepant between the two breeds.The further studies for the differentially expressed genes and alternative splicing will better understand the molecular mechanisms underlying sheep fat-tail.