The moelcular basis of the mechanisums on that the extracellular calcium ions regulate the differentiation of human esopahgeal epithelial cells

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Extracellular calcium ions (Ca^<2+>) are important in regulating the differentiation of squamous epithelial cells. We tried to clarify the mechanisms of the differentiation of human esophageal epithelial cells using the primary culture of human esophageal epithelial cells (EECs), which can be differentiated by increasing the concentration of extracellular Ca^<2+>. And we got three new findings as the below :1) A calcium-binding protein S100P showed a Ca^<2+> inducible expression in human EECs. S100P was detected in vivo in the suprabasal and the upper few layers of the epithelium, in which the proliferating cells were also located. S100P expression is transiently expressed during the early stage of differentiation.2) Human esophageal epithelial cells sequentially produce different S100 proteins, including S100A2, S100A6, S100P and CAAF1 (S100A12) in the process of differentiation.3) Human CAAF1 proteins exist as noncovalent homodimers, and Ca^<2+> and Zn^<2+> synergistically promote the oligomeric self-association.These findings suggest that within esophageal epithelial cells S100 proteins might play important roles in cell differentiation during specific stages. An understanding of calcium function in the squamous epithelial cells will require the analysis of calcium-binding proteins, especially S100 proteins.