This study investigated expressions of miR-27a-3p, miR-29B-2, miR-142-5p, miR-148a in Holstein with low (LSCC) and high somatic cell counts (HSCC). Relationships between miRNAs, SCC and key milk quality parameters were examined. Milk was aseptically collected from multiparous Holsteins in mid-lactation on a dairy farm, and cows were grouped by SCC (200,000 cells/mL). miRNAs expressions were quantified by RT-qPCR, and target genes, Protein-Protein Interaction, and pathway analysis were also conducted. In HSCC, all samples were CMT positive (1.91±0.17). The overall SCC was approximately 320,000 cells/mL, with values around 60,000 cells/mL in the LSCC and 540,000 cells/mL in HSCC. Milk composition parameters were similar between groups, while electrical conductivity (EC) was higher in HSCC. miR-27a-3p and miR-29B-2 were upregulated by approximately 3-fold in HSCC, whereas miR-148a showed more than 6-fold upregulation. miR-27a- 3p correlated positively with miR-29B-2, miR-148a, and EC. miR-29B-2 was positively correlated with miR-148a, SCC, fat, and EC. miR-142-5p showed negative correlation with protein, while miR-148a was positively correlated with SCC. A total of 1,020 target genes were identified, with PTEN being a common target of all four miRNAs, while SMAD3, TGFB2, OTUD4, and RPS6KA5 were regulated by three. Network analysis revealed 84 proteins engaged in 402 interactions. MCODE identified key genes related to host response, lipid metabolism, inflammation, and apoptosis. The results provide insights into the molecular mechanisms underlying mammary gland health and potential targets for improving milk quality.
Fatma Çagla Güzel (Wed,) studied this question.