As an important type of noncoding RNA molecules, long non-coding RNAs (lncRNAs) act as versatile players in various biological processes. However, little is known about lncRNA regulators during sheep muscle growth. To explore functional lncRNAs during sheep muscle growth, we systematically investigated lncRNAs using strand-specific Ribo-Zero RNA sequencing at three key developmental stages in Hu sheep. A total of 6924 lncRNAs were obtained, and the differentially expressed lncRNAs and genes were screened from (control vs. experiment) fetus vs. lamb, lamb vs. adult, and fetus vs. adult comparisons, respectively. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis results correlated well with the sequencing data. Moreover, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases showed that the target genes of the differentially expressed lncRNAs were significantly enriched in organ morphogenesis, skeletal system development as well as response to stimulus and some other terms related to muscle. Furthermore, a co-expression network of the differentially expressed target genes and lncRNAs was constructed and well-known muscle growth regulators such as retrotransposon-like 1 and Junctophilin-2 were included. Finally, we investigated the expression profiles of seven lncRNAs and their target genes, and found that they played vital roles in muscle growth. This study extends the sheep muscle lncRNA database and provides novel candidate regulators for future genetic and molecular studies on sheep muscle growth, which is helpful for optimizing the production of mutton.

Runt-related transcription factor 1 translocation partner 1 (RUNX1T1), a potential novel regulator of adipogenesis, exists in two splice variants: a long (RUNX1T1-L) and a short (RUNX1T1-S) isoform. However, there is no data showing the existence of RUNX1T1 in ovine subcutaneous fat at different stages of developmental and its role on ovine adipogenesis. Therefore, the objectives of this study were to evaluate the presence of RUNX1T1 in subcutaneous fat of five-day-old to 24-month-old sheep and to investigate the role of RUNX1T1 in ovine adipogenesis. In this study, we detected a 1829 bp cDNA fragment of RUNX1T1 which contains a 1815 bp coding sequence that encodes 602-amino acid and 14 bp of 5′ untranslated region, respectively. The amino acid sequence of RUNX1T1 has 31.18–94.21% homology with other species’ protein sequences. During fat development, the RUNX1T1 protein expression was higher in subcutaneous fat of 24-month-old Hu sheep. In addition, the expression of RUNX1T1-L mRNA decreased first, then subsequently increased during ovine preadipocyte differentiation. Knockdown of RUNX1T1-L in ovine preadipocytes promoted preadipocyte differentiation and lipid accumulation. Taken together, our data suggests that RUNX1T1 is an important functional molecule in adipogenesis. Moreover, it showed for the first time that RUNX1T1-L was negatively correlated with the ovine preadipocyte differentiation.