Identification and profiling of microRNAs involved in the regenerative involution of mammary gland.

Regenerative involution is important for the subsequent lactation, but molecular mechanism has not been revealed. The crucial miRNA in tissue development indicates that miRNAs might participate in regenerative involution. In the present study, the mammary tissues of the dairy goats (n = 3) were collected via biopsy at wk-8 (time to dry off), -6, -4, -1, and + 1 relative to lambing for the Hematoxylin and Eosin staining and miRNA sequencing. Alveolar structures collapsed during regenerative involution, but the structures remained intact and distended. Among the 50 miRNA expression trajectories categorized by short time-series expression miner, two significant patterns were clustered. The differentially expressed miRNAs in the two patterns were mainly related to the self-renewal of tissue and enriched in pathways containing vesical-mediated transport, tissue development, tube development, vasculature development and epithelial development. The identification of the miRNAs will help in elucidating their regulatory roles in mammary gland development.