Growth hormone suppresses the expression of IGFBP-5, and promotes the IGF-I-induced phosphorylation of Akt in bovine mammary epithelial cells

Kazuhito Sakamoto, Tomoki Yano, Takuya Kobayashi, Akihiko Hagino, Hisashi Aso, Yoshiaki Obara

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Growth hormone (GH) plays a specific role to inhibit apoptosis in the bovine mammary gland through the insulin-like growth factor (IGF)-I system, however, the mechanism of GH action is poorly understood. In this study, we show that GH dramatically inhibits the expression of IGFBP-5, and GH along with IGF-I enhanced the phosphorylation of Akt through the reduction of IGF binding protein (IGFBP)-5. To determine how GH affects Akt through IGF-I in bovine mammary epithelial cells (BMECs), we examined the phosphorylation of Akt in GH treated BMECs and found that IGF-I induced phosphorylation of Akt was significantly enhanced by the treatment with GH. We demonstrated that GH reduces mRNA and protein expression of IGFBP-5 in BMECs, but it does not affect the expression of IGFBP-3. To determine that the enhanced effect of the Akt phosphorylation by the treatment of GH is due to the inhibition of the expression of IGFBP-5, we examined the effect of IGFBP-3 and -5 on the phosphorylation of Akt through IGF-I in the GH-treated BMECs. The phosphorylation of Akt was inhibited in a dose-dependent manner when IGFBP-5 was added at varying concentrations and was also inhibited in the presence of IGFBP-3. The results of this study suggest that GH plays an important role on mammary gland involution in bovine mammary epithelial cells.

Original languageEnglish (US)
Pages (from-to)260-272
Number of pages13
JournalDomestic Animal Endocrinology
Volume32
Issue number4
DOIs
StatePublished - May 2007

Keywords

  • Akt
  • Bovine mammary epithelial cells
  • GH
  • IGF-I
  • IGFBP-5

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology
  • Endocrinology

Fingerprint Dive into the research topics of 'Growth hormone suppresses the expression of IGFBP-5, and promotes the IGF-I-induced phosphorylation of Akt in bovine mammary epithelial cells'. Together they form a unique fingerprint.

Cite this