The human MUC2 gene maps to chromosome 11p15, where three additional mucin genes have been located, and encodes the most abundant gastrointestinal mucin normally expressed in the intestinal goblet cell lineage. However, in pathological conditions, including colorectal cancer, MUC2 can be abnormally expressed. Therefore, it is of considerable interest to understand the regulation of the MUC2 gene and how the mechanism is altered in colon cancer. Toward this goal, we have isolated a group of overlapping clones (contig) spanning 85 kilobases harboring the entire MUC2 locus, including sequences located upstream of the gene. Detection of two DNase I-hypersensitive sites in the 5 region of the MUC2 gene suggests the presence of DNA regulatory elements. To better characterize this region, we have sequenced 12 kilobases of the upstream region and analyzed it for functional activity by cloning portions of it into a luciferase reporter vector and assaying for promoter/enhancer activity using a transient transfection assay. A fragment from the AUG translational initiation codon ؉1 to ؊848 confers maximal transcriptional activity in several intestinal cell lines. Elements located further upstream exert a negative effect on the expression of the reporter gene when tested in conjunction with homologous or heterologous promoters. The same pattern of expression is observed when the MUC2/luciferase constructs are transfected into HeLa cells, which do not express the endogenous MUC2 gene. However, the level of activity in HeLa cells is at least an order of magnitude higher, suggesting that additional sequences singularly or in combination are responsible for the tissue-and cell lineage-specific expression of MUC2. Finally, we have identified an additional mucin-like gene (MUCX), located upstream of MUC2. We show that this MUCX gene, that is transcribed in opposite orientation to that of MUC2, is expressed with a pattern distinct from that of MUC2, yet similar to that of MUC5B and MUC6, two additional mucin genes located at chromosome 11p15. Recent information on the order of the mucin genes at chromosome 11p15 suggests that MUCX may be MUC6, one of the already identified mucin genes, or a novel one, yet to be fully characterized.Mucins are the major components of mucus, the visco-elastic substance that protects and lubricates epithelial mucosa, including that of the gastrointestinal tract. They are highly glycosylated molecules, and up to 80% of their mass consists of O-linked glycosyl residues. Recently, the cloning of full-length or partial cDNA sequences of mucins expressed in different tissues has greatly facilitated investigations of the polypeptide moieties (reviewed in Refs.

On 18q, frequently deleted in late stage colorectal cancers, a gene, Deleted in Colon Cancer (DCC), has been identi®ed and postulated to play a role as a tumor suppressor gene. DCC is retained in the majority of mucinous tumors, which produce high levels of mucins, and seems to be preferentially expressed in intestinal goblet cells. To investigate whether DCC is related to mucin expression and can modulate the transformed phenotype, we introduced a full-length DCC cDNA into HT29 cells, which can be induced in vitro to express MUC2, the gene that encodes the major colonic mucin. Expression of DCC did not modulate constitutive or induced expression of MUC2, nor did DCC induce a mature goblet cell phenotype. However, HT29 clones expressing high and low levels of DCC protein showed a signi®cant decrease in cell proliferation and tumorigenicity. Furthermore, increased shedding and an elevated rate of spontaneous apoptosis were associated with higher levels of expression of DCC. In summary, while restoration of DCC expression in a human colon carcinoma cell line did not in¯uence expression of di erentiation markers, DCC expression did a ect the growth and tumorigenic properties of the cells suggesting that DCC can modulate the malignant phenotype of colon cancer.

Background: Inherited disorders of fibrinogen are rare and affect either the quantity (hypofibrinogenaemia and afibrinogenaemia) or the quality of the circulating fibrinogen (dysfibrinogenaemia). Extensive allelic heterogeneity has been found for all three disorders: in congenital afibrinogenaemia .30 mutations, the majority in FGA, have been identified in homozygosity or in compound heterozygosity. Several mutations have also been identified in patients with hypofibrinogenaemia; many of these are heterozygous carriers of afibrinogenaemia null mutations. Objective: To report the case of a patient from Slovakia diagnosed with hypofibrinogenaemia characterised by fibrinogen concentrations of around 0.7 g/l. Results: The patient was found to be heterozygous for a novel missense mutation W253C (W227C in the mature protein) in the C-terminal globular domain of the fibrinogen c chain. Co-expression of the W253C FGG mutant cDNA (fibrinogen Bratislava) in combination with wild-type FGA and FGB cDNAs showed that fibrinogen molecules containing the mutant c chain can assemble intracellularly but are not secreted into the media, confirming the causative nature of the identified mutation. Conclusions: Current analysis of fibrinogen Bratislava indicates that the domains important for the processes of hexamer assembly and hexamer secretion should not be considered as strictly restricted to one or other fibrinogen chain.