ABSTRACT
BACKGROUND AND OBJECTIVES: MUC5AC is known to be a major secretory mucin in goblet cells of the mucosa of human lower respiratory tract. But in our preliminary study, we found that the levels of MUC8 mRNAs were significantly increased in the biopsy specimens of the nasal polyps whereas other mucin genes were not. This suggests the possibility that MUC8 might be one of the major overexpressed mucins in the nasal polyps. The purpose of this study is to investigate the cellular location of MUC5AC and MUC8 mRNA. Material and methods : Normal posterior ethmoid mucosa and the polyp tissue were fixed in 4% paraformaldehyde and were hybridized with the RNA riboprobe for MUC8 and the oligonucleotide probe for MUC5AC in the presence of digoxigenin (DIG). RESULT: In the normal posterior ethmoid mucosa, MUC 5AC mRNA and MUC8 mRNA were barely expressed in the epithelium and the submucosal glands. In the polyp epithelium, the expression of MUC 5AC mRNA was localized in the cytoplasm of goblet cells and the expression of MUC8 mRNA was strongly localized in the nucelus of the goblet cells, and weakly localized in the cytoplasm of the goblet cells. MUC8 mRNA was also expressed in low levels in the nucleus of the submucosal glands. CONCLUSION: MUC8 mRNA is localized mainly in the nucleus of goblet cells and is one of the major mucin genes overexpressed in goblet cells of thnasal polyp.