Objective: There is a strong relationship between the content of beneficial fatty acids in milk and milk fat metabolic activity in the mammary gland. To improve milk quality, it is therefore necessary to study fatty acid metabolism in bovine mammary gland tissue. In adipose tissue, peroxisome proliferator-activated receptor gamma (PPARG), the core transcription factor, regulates the fatty acid metabolism gene network and determines fatty acid deposition. However, its regulatory effects on mammary gland fatty acid metabolism during lactation have rarely been reported.Methods: Transcriptome sequencing was performed during the prelactation period and the peak lactation period to examine mRNA expression. The significant upregulation of PPARG drew our attention and led us to conduct further research.Results: According to bioinformatics prediction, dual-luciferase reporter system detection, real-time quantitative reverse transcription polymerase chain reaction and Western blotting, miR-130a and miR-130b could directly target PPARG and inhibit its expression. Furthermore, triglyceride and oil red O staining proved that miR-130a and miR-130b inhibited milk fat metabolism in bovine mammary epithelial cells (BMECs), while PPARG promoted this metabolism. In addition, we also found that the coexpression of miR-130a and miR-130b significantly enhanced their ability to regulate milk fat metabolism.Conclusion: In conclusion, our findings indicated that miR-130a and miR-130b could target and repress PPARG and that they also have a functional superposition effect. miR-130a and miR-130b seem to synergistically regulate lipid catabolism via the control of PPARG in BMECs. In the long-term, these findings might be helpful in developing practical means to improve high-quality milk.

Milk, known for its high content of short- and medium-chain fatty acids and unsaturated fatty acids, has attracted substantial attention due to its nutritional and health value. The regulation of fatty acid metabolism by non-coding RNAs has become a subject of growing attention, particularly in relation to fatty acid production at the transcriptional/epigenetic and post-transcriptional levels. This study established the circRNA-11228/miR-103/INSIG1 (insulin-inducible gene) regulatory network using methods such as qRT-PCR, dual luciferase reporting, and Western blot, with INSIG1 serving as the starting point. The experimental validation of circRNA-11228’s impact on cholesterol levels, lipid droplet secretion, and unsaturated fatty acid content was conducted using various assays, including triglycerides, cholesterol, oil red O, andEdU(5-ethynyl-2’-deoxyuridine) in bovine mammary epithelial cells (BMECs). Furthermore, the transfection of mimics and inhibitors synthesized from miR-103 into BMECs confirmed that miR-103 can promote cholesterol synthesis and lipid droplet secretion. Conversely, the INSIG1 gene was found to inhibit cholesterol synthesis and lipid droplet secretion. The “remediation” experiment validated the ability of miR-103 to alleviate the cellular effect of circRNA-11228. Taken together, our findings indicate that the binding of circRNA-11228 to miR-103 inhibits the expression of the target gene INSIG, thereby regulating milk fat production in BMECs. This study offers novel insights into producing high-quality milk and new ways to improve the dietary composition of residents.

Background: Milk fat metabolism is a complex process regulated by non-coding RNAs. circRNAs (circRNAs) can act as miRNA sponges to regulate target gene expression. Purpose: This study aimed to investigate the role and mechanism of the circRNA_01754/miR-302c/LATS2 axis in regulating milk fat metabolism in bovine mammary epithelial cells (BMECs). Methods: mRNA sequencing was performed on bovine mammary gland tissues from different lactation stages to analyze the expression profiles. The interactions between circRNA_01754, miR-302c, and LATS2 were verified using dual-luciferase reporter assays, qRT-PCR, and Western blot. The functional effects on triglyceride (TAG) and cholesterol synthesis were assessed. Results: CircRNA_01754 was identified as a direct sponge for miR-302c. Overexpression of circRNA_01754 increased LATS2 expression by sequestering miR-302c. Functional experiments showed that circRNA_01754 and LATS2 promoted TAG synthesis, whereas miR-302c inhibited it. Furthermore, miR-302c was found to regulate the expression of YAP1, a key effector of the Hippo pathway, through LATS2. Conclusions: Our findings reveal that circRNA_01754 promotes milk fat synthesis by acting as a ceRNA for miR-302c to upregulate LATS2. This study lays the groundwork for producing high-quality milk and opens up new avenues for enhancing public dietary health.