MUC12 Products

Human MUC12 (Mucin 12) is a novel mucin of epithelial mucins, which are large, secreted or cell surface glycoproteins involved in epithelial cell protection, adhesion modulation, and signaling. Using differential display on RNA from paired normal colonic mucosa and primary colorectal tumor, MUC12 is identified as one of the 2 partial cDNAs representing novel mucin genes as well as MUC11. They are downregulated in colorectal tumors.The deduced MUC12 protein contains a predicted transmembrane domain, 2 extracellular cysteine-rich EGF-like domains, a coiled-coil region, and a domain consisting of serine-, threonine-, and proline-rich degenerate tandem repeats of 28 amino acids, a structural feature typical of mucins. Human MUC12 shares high sequence homology with MUC3 and MUC4 . Northern blot analysis of 50 different normal tissues detected MUC12 expression in colon, pancreas, prostate, and uterus, with highest expression in colon. The MUC12 transcript is large, estimated to be longer than 12 kb. Expression of MUC12 was downregulated or absent in 6 of 15 (40%) colorectal tumors, as compared with matched normal colonic tissues. MUC12 expression was not detected in any of 6 colorectal cancer cell lines examined. Epitheial mucins are secreted glycoproteins that play roles in cell protection, adhesion modulation and signaling. MUC 12 is a novel mucin gene and may be involved in epithelial cell growth regulation. MUC 12 is down-regulated in colorectal cancers.