Lactogenic hormones alter cellular and extracellular microRNA expression in bovine mammary epithelial cell culture

Abstract

BackgroundBovine milk contains not only a variety of nutritional ingredients but also microRNAs (miRNAs) that are thought to be secreted by the bovine mammary epithelial cells (BMECs). The objective of this study was to elucidate the production of milk-related miRNAs in BMECs under the influence of lactogenic hormones.ResultsAccording to a microarray result of milk exosomal miRNAs prior to cellular analyses, a total of 257 miRNAs were detected in a Holstein cow milk. Of these, 18 major miRNAs of interest in the milk were selected for an expression analysis in BMEC culture that was treated with or without dexamethasone, insulin, and prolactin (DIP) to induce a lactogenic differentiation. Quantitative polymerase chain reaction (qPCR) results showed that the expressions of miR-21–5p (P = 0.005), miR-26a (P = 0.016), and miR-320a (P = 0.011) were lower in the DIP-treated cells than in the untreated cells. In contrast, the expression of miR-339a (P = 0.017) in the cell culture medium were lower in the DIP-treated culture than in the untreated culture. Intriguingly, the miR-148a expression in cell culture medium was elevated by DIP treatment of BMEC culture (P = 0.018). The medium-to-cell expression ratios of miR-103 (P = 0.025), miR-148a (P < 0.001), and miR-223 (P = 0.013) were elevated in the DIP-treated BMECs, suggesting that the lactogenic differentiation-induced secretion of these three miRNAs in BMECs. A bioinformatic analysis showed that the miRNAs down-regulated in the BMECs were associated with the suppression of genes related to transcriptional regulation, protein phosphorylation, and tube development.ConclusionThe results suggest that the miRNAs changed by lactogenic hormones are associated with milk protein synthesis, and mammary gland development and maturation. The elevated miR-148a level in DIP-treated BMECs may be associated with its increase in milk during the lactation period of cows.

MicroRNA roles in signalling during lactation: an insight from differential expression, time course and pathway analyses of deep sequence data

“…These highly, commonly expressed miRNAs suggest their potential regulatory functions in mammary gland development and productivity. This notion is supported by biological process and pathway enrichment results since many basic cellular and molecular processes2728 and immunlogical pathways were enriched for these commonly highly expressed miRNAs (Table 2). …”

Milk MicroRNAs in Health and Disease

“…A comparison of milk microRNA contents with mammary gland cell profiles by small RNA sequencing (Hou et al., ; Ju et al., ; Li et al., ; Luoreng, Wang, Mei, & Zan, ; Shen et al., ) supports the epithelial origin of these microRNAs because the most enriched microRNAs in milk are also highly enriched in mammary glands cells and are of high importance for lactation (Chen et al., ; Do et al., , ; Gu et al., ; Muroya et al., ).…”

“…MicroRNA hsa‐miR‐148a‐3p is consistently the most abundant microRNA in breast milk, most likely because of its importance for lactation and its enrichment in mammary gland cells (Chen et al., ; Do, Dudemaine, Li, & Ibeagha‐Awemu, ; Gu et al., ; Muroya et al., ). It is then with little surprise that this microRNA is the most studied milk microRNA (Benmoussa et al., ; Golan‐Gerstl et al., ; Melnik, ; Melnik & Schmitz, , ; Simpson et al., ; van Herwijnen et al., ).…”

Roles of MicroRNA across Prenatal and Postnatal Periods

“…The expression of cellular and extracellular miRNA in bovine mammary epithelial cells changes under the influence of lactogenic hormones such as prolactin [103]. These findings suggest that miRNA is implicated in the physiological processes of milk synthesis under normal conditions.…”