ΔFosB regulates Ca2+ release and proliferation of goat mammary epithelial cells

Delta FosB is a member of the family of transcription factor activating proteins-1 (AP-1) and is known to play important roles in Ca2+ metabolism processes of osteoblast formation and differentiation in humans and rodents. The postpartum mammary gland is one of the significant organs for Ca2+ metabolism processes. However, very little information is available on the role of Delta FosB in goat mammary gland. In this investigation, the full-length cDNA of Delta FosB from Xinong Saanen dairy goats was cloned, which contains an open-reading frame (ORF) of 723 bp encoding 240 amino acids. The amino acid sequence is highly homologous with cattle (99.17%). Quantitative real time PCR (QRT-PCR) and western blotting assays showed that Delta FosB was expressed in goat heart, liver, lung, and breast, but little in the hypophysis and spleen. The fluorescence signals revealed that the Ca2+ was decreased in goat mammary epithelial cells (GMECs) over-expressed Delta FosB at 72 h. Consistently, intracellular Ca2+ was increased in GMECs suppressing expressed Delta FosB at 72 h. QRT-PCR assay showed that Delta FosB positively regulated the mRNA expression of runt related transcription factor 2 (Runx2), SMAD family member 4 (Smad4), S100 calcium binding protein A4 (S100A4) and S100 calcium binding protein A13 (S100A13) genes in GMECs, which had been proven to be relative to calcium metabolism in humans and rodents. Ca2+ could induce a dose-dependent increase of the Delta FosB mRNA expression and a dose-dependent decrease in cell viability when the GMECs were treated with CaCl2. Suppressing Delta FosB expression in GMECs also inhibited the cell viability. These discoveries suggest that Delta FosB plays important roles in regulating Ca2+ release and proliferation of the GMECs, which may prove useful in regulation of milk production. (C) 2014 Elsevier B.V. All rights reserved.