Analysis of Associations Between Expression Patterns of miRNA miR-767, miR-335-3p and miR-106b-5p and Metabolites of Milk and Serum of Goats (Capra hircus)

The presented work characterised the expression profile of microRNAs miR-767, miR-335-3p and miR-106b-5p in milk and blood serum samples of goats from week 1 to week 23 of lactation, taking into account the dynamics of some protein and lipid metabolites of milk and blood. The expression of microRNAs in milk was associated with some changes in the analysed metabolites. MiR-767 was positively correlated with milk protein, casein, and fatty acids (C18:0, MCFA and MUFA). For miR-335-3p, it was negatively correlated with cholesterol and triglycerides of blood, but positively correlated with milk fat and MCFA, SCFA, TFA, and SFA including C14:0, C16:00 and C18:0. Expression of miR-106b-5p showed a unidirectional association with total blood cholesterol. Among all three serum microRNAs analysed, only miR-106b-5p expression was positively associated with milk protein, casein, LCFA and MUFA content. The high predictive effect (R2 > 0.800, p < 0.001) suggests a significant role of microRNAs synthesized by the mammary gland (miR-767 and miR-335-3p) for milk protein and fat components and miR-106b-5p circulating in the blood for milk protein and casein. The results of our study suggest that an increase in the expression level of miR-767, miR-335-3p in milk and miR-106b-5p in blood serum leads to activation of transcription and translation of their target genes, which is phenotypically expressed by an increase in the values of a range of protein and fat components of goat milk. The study of the role of miRNAs in the regulation of lactation is a promising area of modern molecular biology, which has great potential for increasing the efficiency of dairy production, improving product quality and in programs for the development of predictive biomarkers.