Expression of MUC1 mucin in full-term pregnancy human placenta

MUC1 mucin is a component of glycocalyx in human endometrium and may play an important role in generation of "receptive window" at embryo implantation. Considering that MUC1 expression in human placenta is changed during pregnancy, and that MUC1 structure and function are not completely known in this organ, we have undertaken isolation of this mucin and detection of glycan epitopes, since they are crucial for its properties. Samples of human placenta were homogenized and MUC1 was extracted in different conditions with the use of ionic or non-ionic detergents. Identification of this glycoprotein was performed by Western and lectin blotting, after its purification on Sepharose 4B column. The best extraction of MUC1 glycoprotein was achieved with a non-ionic detergent, Triton X-100. Reactions with anti-MUC1 antibody showed a few glycoforms with molecular weights between 116 and 205 kDa, with the most visible glycoform approximating 205 kDa. Reactions with lectins enabled detection of carbohydrate antigens, such as T and Tn with sialic acid linked by alpha2, 3 and to a lesser extent by alpha2, 6 bond. MUC1 mucin is present in several glycoforms on the maternal side of human placenta after term delivery. They contain short glycan structures, similar to some tumor carbohydrate antigens.