MicroRNAs (miRNAs) have a great influence on various physiological functions. A lot of high-throughput sequencing (HTS) research on miRNAs has been executed in the caprine mammary gland at different lactation periods (common milk lactation and dry period), but little is known about differentially expressed miRNAs in the caprine mammary gland of colostrum and peak lactation periods.

A recent study led by researchers from Yangling Vocational & Technical College identified 131 differentially expressed miRNAs, including 57 known miRNAs and 74 potential novel miRNAs in the colostrum and peak lactation miRNA sequencing libraries. In addition, compared with differentially expressed miRNAs in the peak lactation period, 45 miRNAs in the colostrum lactation period were remarkably upregulated, whereas 86 miRNAs were markedly downregulated.

 

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Distribution of small RNAs among different categories in the colostrum and peak lactation libraries. The clean reads were annotated and classified as miRNA, rRNA, tRNA and snoRNA in GenBank and Rfam databases. Partial reads were not annotated

 

The expressions of 10 randomly selected miRNAs was analyzed through stem-loop real-time quantitative PCR (RT-qPCR). Their expression patterns were the same with the sequencing results. Pathway analysis suggested that oestrogen, endocrine, adipocytokine, oxytocin and MAPK signalling pathways act on the development of mammary gland and milk secretion importantly. In addition, the miRNA-target-network showed that the bta-miR-574 could influence the development of mammary gland and lactation by leptin receptor (LEPR), which was in the adipocytokine signalling pathway.

These findings suggested that the profiles of miRNAs were related to the physiological functions of mammary gland in the colostrum and peak lactation periods. The biological features of these miRNAs may help to clarify the molecular mechanisms of lactation and the development of caprine mammary gland.

 

Reference
J. Hou, X. An, Y. Song, B. Cao, H. Yang, Z. Zhang, W. Shen, Y. Li, et al. (2017) Detection and comparison of microRNAs in the caprine mammary gland tissues of colostrum and common milk stages. BMC Genetics 18:38 doi: 10.1186/s12863-017-0498-2 [article]

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