DEVELOPMENTAL EXPRESSION OF MUCIN GENES MUC1 AND MUC2

The mucin gene MUC1, is expressed in a number of human ductal epitheli a in vivo including those within the pancreas, mammary gland, kidney a nd genital ducts. Further it is expressed at a high level in certain t umours and tumour-derived cell lines. MUC2 was initially isolated from a human jejunum cDNA library and is thought to be one of the major in testinal mucin genes, though it is also expressed in the trachea. We h ave examined the developmental expression of these two mucin genes in human tissues. High level expression of MUC1 has been seen by 12.5 wee ks of gestation in the epithelia of the distal respiratory tract and t he collecting ducts in the kidney. By 18 weeks MUC1 mRNA is detectable in the colon but pancreatic expression of MUC1 is not seen until late in gestation. MUC2 mRNA is seen by 12 weeks of gestation in the jejun um, ileum and colon, and in large bronchioles of the lung by 18 weeks. The pattern of expression of MUC1 suggests that this mucin may not be involved in early ductal obstruction in the CF pancreas, but both MUC 1 and MUC2 may play a role in the development of intestinal disease an d MUC1 in early respiratory disease associated with CF.