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Updated: May 25, 2025
Bovine Mammary Gland Biopsy Techniques
Published on: December 23, 2018
MicroRNA-21 Promotes the Viability, Proliferation and Milk Fat Synthesis of Ovine Mammary Epithelial Cells by
Liyan Hu1, Jiqing Wang1, Zhiyun Hao1
1College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
Abstract:
MicroRNAs (miRNAs) are short endogenous non-coding RNAs and play important roles in regulating mammary development and activities of ovine mammary epithelial cells (OMECs), which affect the milk yield and milk ingredient contents of ewes. We previously found that miR-21 was highly expressed in ovine mammary tissue, while the regulatory mechanisms of miR-21 underlying mammary development and lactation performance are still unclear. Accordingly, in this study, we investigated the functions of miR-21 in the activities of OMECs, and validated the target relationship of miR-21 with a predicted target gene programmed cell death 4 (PDCD4) by a dual-luciferase reporter assay. Finally, we investigated the regulatory effect of PDCD4 on the viability, proliferation and milk fat synthesis of OMECs. The overexpression of miR-21 significantly increased the viability of OMECs, the number and proportion of Edu-labeled positive OMECs, as well as the contents of triglyceride in OMECs. In fact, miR-21 inhibitor obtained opposite results with miR-21 mimics. The results obtained from the dual luciferase report and RT-qPCR assays confirmed that the seed sequence of miR-21 can complementarily combine with the 3'-untranslated regions (3'-UTR) of PDCD4, and miR-21 decreased the luciferase activity of PDCD4. Meanwhile, miR-21 also reduced the expression of PDCD4. These results indicate that PDCD4 is a target gene of miR-21. It was further found that PDCD4 decreased the viability and triglyceride content of OMECs, and the number and proportion of Edu-labeled positive OMECs. These findings suggest that miR-21 promotes the viability, proliferation and milk fat synthesis of OMECs by down-regulating the expression of PDCD4. The results revealed the regulatory mechanism by which miR-21 affected the activities and milk fat synthesis of OMECs in sheep.
Insights
MicroRNAs (miRNAs) regulate sheep mammary cells. miR-21 promotes cell viability, proliferation, and milk fat synthesis by down-regulating programmed cell death 4 (PDCD4).
Area of Science:
- Molecular Biology
- Animal Science
- Gene Regulation
Background:
- MicroRNAs (miRNAs) are crucial regulators of mammary gland development and function in sheep.
- miR-21 is highly expressed in ovine mammary tissue, but its specific roles remain unclear.
- Understanding miRNA functions is key to improving milk yield and composition.
Purpose of the Study:
- To investigate the function of miR-21 in ovine mammary epithelial cells (OMECs).
- To validate programmed cell death 4 (PDCD4) as a direct target of miR-21.
- To elucidate the regulatory mechanism of miR-21 and PDCD4 in OMEC activities and milk fat synthesis.
Main Methods:
- Dual-luciferase reporter assay to confirm miR-21 targeting of PDCD4.
- RT-qPCR to assess gene expression levels.
- Overexpression and inhibition of miR-21 in OMECs to evaluate effects on cell viability, proliferation (EdU labeling), and triglyceride content.
Main Results:
- Overexpression of miR-21 significantly enhanced OMEC viability, proliferation, and triglyceride content.
- miR-21 directly targets and down-regulates PDCD4 expression in OMECs.
- PDCD4 was found to inhibit OMEC viability, proliferation, and milk fat synthesis.
Conclusions:
- miR-21 promotes OMEC viability, proliferation, and milk fat synthesis by inhibiting PDCD4 expression.
- This study reveals a novel regulatory pathway for mammary gland function and milk production in sheep.
- Findings provide insights into miRNA-mediated control of lactation performance.
