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Journal of Animal Science Abstract - Lactation and Mammary Gland Biology

The functional effects and mechanisms by which fibroblast growth factor 2 (FGF2) controls bovine mammary epithelial cells: Implications for the development and functionality of the bovine mammary gland1


This article in JAS

  1. Vol. 95 No. 12, p. 5365-5377
    Received: July 02, 2017
    Accepted: Aug 22, 2017
    Published: November 9, 2017

    3 Corresponding author(s):

  1. W. Jeong*22,
  2. H. Bae22,
  3. W. Lim,
  4. F. W. Bazer§,
  5. H. Lee 3# and
  6. G. Song 3
  1. * Department of Animal Resources Science, Dankook University, Cheonan 330-714, Republic of Korea
     Institute of Animal Molecular Biotechnology and Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
     Department of Biomedical Sciences, Catholic Kwandong University, Gangneung, 25601, Republic of Korea
    § Center for Animal Biotechnology and Genomics and Department of Animal Science, Texas A&M University, College Station 77843-2471
    # Department of Animal Science, and Technology, College of Animal Bioscience & Technology, Konkuk University, Seoul, 05029, Republic of Korea


Fibroblast growth factor (FGF) signaling plays essential roles in tissue development and homeostasis. Accumulating evidence reveals that fibroblast growth factor 2 (FGF2) regulates ductal elongation, which requires cell proliferation and epithelial expansion in the mammary gland. However, the function and mechanisms by which FGF2 controls functionality of epithelial cells is less well defined. Here, we demonstrate the functional effects of FGF2 on bovine mammary epithelial (MAC-T) cells and the intracellular signaling mechanisms for these FGF2-induced actions. The current results show that treatment of MAC-T cells with a recombinant FGF2 induced cell proliferation and cell-cycle progression with increased expression of proliferating cell nuclear antigen and cyclin D1. Moreover, FGF2 increased phosphorylation of serine/threonine protein kinase (protein kinase B [AKT]), extracellular signal–regulated kinases 1 and 2 (ERK1/2), Jun N-terminal kinase (JNK), 70 kDa ribosomal S6 kinase (P70S6K), 90 kDa ribosomal S6 kinase (P90S6K), ribosomal protein S6 (S6), and cyclin D1 proteins. These FGF2-induced activations of signaling pathway proteins were inhibited by blocking AKT, ERK1/2, or JNK phosphorylation. The effect of FGF2 to stimulate MAC-T cell proliferation was mediated by activation of FGF receptors (FGFR) and AKT, ERK1/2, and JNK mitogen-activated protein kinase pathways in response to FGF2 stimulation. Furthermore, expression and activation of endoplasmic reticulum (ER) stress–related factors and ER stress–induced MAC-T cell death was reduced by FGF2. Together, these results suggest that the FGF2–FGFR–intracellular signaling cascades may contribute to maintaining and/or increasing numbers of mammary epithelial cells by inducing proliferation of mammary epithelial cells and by protecting cells from ER stress responses. Therefore, this study provides evidence that FGF2 signaling is a positive factor for mammary gland remodeling and for increasing persistency of milk production.

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