GSE131057
Cow mammary glande miRNomes
Effect of breed in mid lactation Holstein (H) and Montbéliarde (M) cows on mammary glande miRNA profile. Genetic polymorphisms are known to influence milk production and composition. However, genomic mechanisms involved in the genetic regulation of milk component synthesis are not completely understood. MicroRNAs (miRNA) regulate gene expression. The objective of the present study was to compare mammary gland miRNomes of two dairy cow breeds, Holstein and Montbéliarde, with different dairy performances.  Milk, fat, protein, and lactose yields were lower in Montbéliarde than in Holstein cows. MiRNomes obtained using RNA-Seq technology from the mammary glands of Holstein (n = 5) and Montbéliarde (n = 6) lactating cows revealed 623 distinct expressed miRNAs, among which 596 were known and 27 were predicted miRNAs. The comparison of their abundance in the mammary gland of Holstein versus Montbéliarde cows showed 22 differentially expressed miRNAs (Padj = 0.05). Among them, 11 presented a fold change =2, with 2 highly expressed miRNAs (miR-100 and miR-146b). Without taking into account the fold change, the differential miRNA with the highest abundance was miR-186, which is known to inhibit cell proliferation and epithelial-to-mesenchymal transition. Data mining showed that the 17 differentially expressed miRNAs with more than 20 reads on average, regulate mammary gland plasticity and may be related to the observed differences in milk production between Holstein and Montbéliarde, which are two breeds with different mammogenic potential. Some of the 17 miRNAs could potentially target mRNAs involved in signaling pathways (such as mTOR) and in lipid metabolism, thereby suggesting that they could influence milk composition.  In conclusion, we showed differences in mammary gland miRNomes of two dairy bovine breeds. These differences suggest a potential role of miRNAs in mammary gland plasticity and in milk component synthesis related to milk production and composition. Overall design: Comparaison of miRNome of mammary gland obtain by biopsies between two breeds of dairy cows (Holstein and Montbéliarde)