Abstract:

The study aimed to understand the genetic basis of long non-coding RNA(lncRNA) regulating skeletal muscle development and fat deposition, the transcriptome analysis was performed on semitendinosus muscle of Lufeng and Leiqiong cattle to explore the lncRNAs that affect skeletal muscle development and fat deposition. In this study, 4 4-month-old female Leiqiong cattle and 4 4-month-old female Lufeng cattle with the same feeding condition were used to extract RNA from the semitendinosus muscle and then perform transcriptome sequencing to screen out differential genes with a threshold of Q < 0.05, and to perform GO and KEGG enrichment analysis and construct lncRNA-miRNA-mRNA and homeopathic targeting regulatory network. Finally, the expression levels of the differential genes were examined by RT-qPCR to verify the reliability of the sequencing results. The results showed that, using Leiqiong cattle as the control group, there were 146 differentially expressed lncRNAs, of which 71 were down-regulated and 75 were up-regulated, 355 differentially expressed mRNAs, of which 180 were down-regulated and 175 were up-regulated, and 34 differentially expressed miRNAs, of which 29 were down-regulated and 5 were up-regulated. GO enrichment analysis of lncRNAs showed that they were mainly enriched in calcium-activated potassium channel activity, actomyosin contractile ring, protein kinase A regulatory subunit binding, myosin Ⅱ complex, etc. KEGG enrichment analysis showed that they were mainly enriched in cGMP-PKG signaling pathway, RNA transport, Gap junction, insulin secretion and other pathways. The cis-targeted regulatory effects was predicted based on the positional relationship of lncRNAs and mRNAs, and 8 mRNAs were screened to be targeted and regulated by 7 lncRNAs, among which DKL1 was associated with muscle development. Then the competitive regulatory sub-networks affecting muscle development and fat deposition were screened by constructing ceRNA regulatory networks, in which ELN and FBOX32 were screened in relation to muscle development, and SLC27A6 and FABP5 were screened in relation to fat deposition. RT-qPCR results showed that the expression levels of the 9 differentially expressed genes were consistent with the expression trends of transcriptome sequencing, indicating that the sequencing results were reliable. In this study, differentially expressed lncRNAs, mRNAs and miRNAs were identified in the semitendinosus muscle of Leiqiong and Lufeng cattle, and the possible regulatory relationships of some differential lncRNAs, mRNAs and miRNAs were found, which are important for revealing the molecular regulatory mechanisms of muscle development and intramuscular fat deposition, and also provide a theoretical basis for improving meat quality of South China Yellow cattle.

Key words: Leiqiong cattle, Lufeng cattle, semitendinosus muscle, lncRNA, RNA-Seq, meat quality