DIGE-based identification of preferentially expressed proteins in early stage of lactogenic differentiation in buffalo (Bubalus bubalis) mammary epithelial cells

Abstract

Proliferation and differentiation of mammary epithelial cells (MECs) is mediated by a complex cross-talk between cell and matrix, interaction among cells, hormones and growth factors. Differentiation of MECs leads to the synthesis and secretion of milk. The mechanism of switching from proliferation to differentiation is yet to be discovered at the molecular level. Differentiation is indicated by the formation of dome in in vitro cultured MECs, the first-ever change phenotypically. The present study was performed in vitro to identify the proteins expressed during initiation of differentiation of MECs in the early stage of lactogenesis using the buffalo MEC (BuMEC) cell line established in our laboratory. The cell line used was in 25th–30th passage. Differentiation was induced using lactogenic hormones (insulin, prolactin, and cortisol) and subcellular fractions (cytosolic and mitochondrial) from proliferative as well as differentiation stage were used to capture differentially expressed proteins (DEPs) by 2D DIGE and MALDI-TOF mass spectrometry. The signaling pathways associated with the DEPs were observed through bioinformatics analysis. The proteomics data were validated by qPCR analysis of selected proteins. The annexins such as annexin-I, II, and V and the S100 proteins (S100A4, S100A2, and S100A11) may have a crucial role in the initiation of differentiation and subsequently lactogenesis by MECs.