MiR-139 suppresses β-casein synthesis and proliferation in bovine mammary epithelial cells by targeting the GHR and IGF1R signaling pathways

BMC Vet Res. 2017 Nov 25;13(1):350. doi: 10.1186/s12917-017-1267-1.

Abstract

Background: MicroRNAs have important roles in many biological processes. However, the role of miR-139 in healthy mammary gland remains unclear. The objective of this study was to investigate the effects of miR-139 on lactation in dairy cows.

Results: Here, we found that miR-139 was down-regulated in mid-lactation dairy cow mammary tissues compared with mid-pregnancy tissues. Then, we prioritized two of potential target genes of miR-139 in cow, growth hormone receptor (GHR) and type I insulin-like growth factor receptor (IGF1R) for further functional studies based on their roles in lactation processes. Dual luciferase reporter assays validated direct binding of miR-139 to the 3'- untranslated region (UTR) of GHR and IGF1R. Moreover, over-expression or silencing of miR-139 affected mRNA levels of GHR and IGF1R in cultured bovine mammary epithelial cells (BMECs). Furthermore, over-expression of miR-139 decreased protein levels of β-casein, proliferation in mammary epithelial cell, and the protein levels of IGF1R and key members of the GHR or IGF1R pathways as well, whereas silencing miR-139 produced the opposite result. Among these signal molecules, signal transducer and activator of transcription-5 (STAT5), protein kinase B (also known as AKT1), mammalian target of rapamycin (mTOR), and p70-S6 Kinase (p70S6K) are involed in β-casein synthesis, and Cyclin D1 is involved in cell proliferation. In addition, silencing GHR decreased protein levels of β-casein, IGF1R, and key members of the IGF1R pathway, whereas co-silencing miR-139 and GHR rescued the expression of GHR and reversed GHR silencing effects.

Conclusions: Our results demonstrate that GHR and IGF1R are target genes of miR-139 in dairy cow. MiR-139 suppresses β-casein synthesis and proliferation in BMECs by targeting the GHR and IGF1R signaling pathways.

Keywords: Growth hormone receptor; Mammary gland; Type I insulin-like growth factor receptor; miR-139; β-casein.

MeSH terms

  • Animals
  • Caseins / biosynthesis*
  • Cattle
  • Cell Proliferation / genetics
  • Cells, Cultured
  • Epithelial Cells / metabolism
  • Female
  • Gene Silencing
  • Lactation / genetics
  • Lactation / metabolism
  • Mammary Glands, Animal / metabolism*
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Pregnancy / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Somatomedin / genetics
  • Receptors, Somatomedin / metabolism
  • Receptors, Somatotropin / genetics
  • Receptors, Somatotropin / metabolism
  • Signal Transduction

Substances

  • Caseins
  • MicroRNAs
  • RNA, Messenger
  • Receptors, Somatomedin
  • Receptors, Somatotropin