Liver microRNA expression revealed the difference in fat metabolism from cattle divergently selected for residual feed intake

MicroRNAs (miRNAs) are short non-coding RNAs that post-transcriptionally regulate expression of mRNAs in many biological pathways. The liver plays a critical role in the synthesis of molecules that are utilized elsewhere to support homeostasis, in converting molecules of one type to another, and in regulating energy balances. We sequenced 48 liver microRNAome from young Angus bulls divergently selected for residual feed intake (RFI). In total we obtained 135 million high quality short sequence reads and more than 93 million unique mapped sequence reads. The top 10 most abundant miRNAs families expressed in liver, represented on average 46-90% of total expressed miRNAs. We did not observe any significant miRNA expression profile for low RFI animals. However, there are distinct miRNA expression patterns separating the animals into two groups that differ significantly in P8 and rib fat thickness. This is consistent with previous finding where high RFI animals had an up-regulated AHR signalling pathway, which plays an important role in fat metabolism. This suggested that some animals have a high RFI value due to excess fat metabolism.