Identification and co-expression analysis of long noncoding RNAs and mRNAs involved in the deposition of intramuscular fat in Aohan fine-wool sheep

Abstract

Background: Intramuscular fat (IMF) content has become one of the most important indicators for measuring meat quality, and levels of IMF are affected by various genes. Long non-coding RNAs (lncRNAs) are widely expressed non-coding RNAs that play an important regulatory role in a variety of biological processes; however, research on the lncRNAs involved in sheep IMF deposition is still in its infancy. Aohan fine-wool sheep (AFWS), one of China's most important meat-hair, dual-purpose sheep breed, provides a great model for studying the role of lncRNAs in the regulation of IMF deposition. We identified lncRNAs by RNA sequencing in longissimus dorsi muscle (LDM) samples of sheep at two ages: 2 months (Mth-2) and 12 months (Mth-12). Results: We identified a total of 26,247 genes and 6,935 novel lncRNAs in LDM samples of sheep. Among these, 606 mRNAs and 408 lncRNAs were differentially expressed. We then compared the structural characteristics of lncRNAs and mRNAs. We obtained target genes of differentially expressed lncRNAs (DELs) and performed enrichment analyses using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). We found that target mRNAs were primarily enriched in lipid metabolism, lipid transport, regulation of primary metabolic processes and developmental pathways. Based on the results of important KEGG pathways, we obtained six candidate lncRNAs that potentially regulate lipid deposition and constructed an lncRNA-mRNA co-expression network that included MSTRG.792.1- SCD , MSTRG.8227.1- ACAA2 , MSTRG.10679.1- FADS2 , MSTRG.21942.1- PLA2G4E , MSTRG.21380.1- FZD4 and MSTRG.9270.1- ULK1 . We speculated that these candidate lncRNAs might play a role by regulating the expression of target genes. We randomly selected five mRNAs and five lncRNAs to verify the accuracy of the sequencing data by qRT-PCR. Conclusions: Our study provided a list of the lncRNAs and mRNAs related to intramuscular lipid deposition in sheep and laid a foundation for future research on regulatory mechanisms.