Stat5a increases lactation of dairy cow mammary gland epithelial cells cultured in vitro.

Signal transducer and activator of transcription 5a (Stat5a) transduces signals of extracellular cytokines and growth factors to the nucleus of mammary gland epithelial cells and thereby regulates gene transcription during pregnancy, lactation, and weaning. However, its function on the milk production of dairy cows needs further investigation. In this experiment, the effects of Stat5a on lactation ability of dairy cow mammary gland epithelial cells (DCMECs) were analyzed. Eukaryotic expression vector pcDNA3.1+-stat5a-αS1 was constructed by inserting stat5a gene into the plasmid vector pcDNA3.1+ and replacing CMV promoter with α-S1-casein 5' flanking sequence. The recombinant vector was stably transfected into DCMECs after geneticin (G418) selection. The proliferation and viability of DCMECs, expression of β-casein and stat5a gene, and the content of lactose were detected. The results showed that stat5a gene in eukaryotic expression vector pcDNA3.1+-stat5a-αS1 was highly expressed in DCMECs and could increase the lactation ability of DCMECs. The associativity of Stat5a with nutrients on the lactation ability of DCMECs was also evaluated. Lysine (Lys), methionine (Met), sodium acetate, β-sodium hydroxybutyrate, and glucose all had more positive effects on the lactation function of DCMECs after pcDNA3.1+-stat5a-αS1 transfection. The proliferation and viability of DCMECs, expression of β-casein and stat5a gene, and contents of lactose and triglyceride were detected. The results revealed that nutrients could promote expression of Stat5a gene to increase lactation of DCMECs. These data help to clarify the function of stat5 gene on lactation and gene regulatory networks linking stat5a.