Proteinaceous components in goat amniotic fluid enhance the expression of keratinocyte differentiation-related proteins

Amniotic fluid (AF) constitutes a dynamic environment containing diverse bioactive molecules derived from both maternal and fetal sources that support fetal development. As the fetus develops in continuous contact with AF, it is plausible that AF influences the formation of the skin epidermis. However, the mechanisms through which AF promotes keratinocyte differentiation remain largely unclear. Here, we showed that goat AF enhanced the expression of key functional proteins involved in epidermal barrier formation, including small proline-rich proteins, loricrin, and transglutaminase. We further obtained the bioactive fractions that promote the expression of these differentiation-related proteins through multistep protein fractionation via column chromatography. Proteomic analysis subsequently revealed 291 candidate proteins, including 85 distinct extracellular proteins, primarily grouped into calcium-binding proteins, proteases and their regulators, extracellular matrix components, and signaling molecules. Collectively, these results suggest that proteins secreted or released into AF contribute to establishing a microenvironment conducive to epidermal differentiation.