Identification and differential expression analysis of microRNAs in the liver and spleen tissues of Yunnan Zebu and Holstein cattle.

Extensive research has shown that miRNAs play a crucial role in regulating biological processes within organisms. This study analyzed miRNAs differentially expressed and potentially associated with immune function and tissue-specific expression in Yunnan Zebu and Holstein cattle. To achieve this, 20 liver and spleen tissue samples from the two cattle breeds were collected for high-throughput miRNA sequencing, with the liver tissue as a reference. The findings revealed that bta-miR-122 and bta-miR-143 are the most abundantly expressed known miRNAs in the liver and spleen tissues of Yunnan Zebu and Holstein cattle, respectively. Additionally, AC_000181.1_27195 and AC_000168.1_14386 emerged as the most highly expressed novel miRNAs in these tissues, exhibiting significant homology with human hsa-miR-3591-3p and hsa-miR-126-3p, respectively. Six differentially expressed miRNAs were selected for validation using stem-loop RT-qPCR, and the results were largely consistent with the high-throughput sequencing data. Functional enrichment analysis of the target genes of these known miRNAs revealed their association with critical metabolic and immune-related pathways in cattle, such as the insulin pathway, mTOR signaling, IFN-γ pathway, and signaling mechanisms mediated by IL5 and IL3. These results enriched the miRNA database for liver and spleen tissues of Yunnan Zebu and Holstein cattle.