COLON CELL DIFFERENTIATION--DCC ROLE IN MUC2 EXPRESSION

Project: Research project

Project Details

Description

The DCC gene is a potential tumor suppressor gene whose deletion or
inactivation plays a role in colonic tumor progression. Recent evidence
suggests that it plays a role in colonic goblet cell differentiation and
mucin production, consistent with its less can also be effected by inducers
which interact with metabolic processes and signal transduction pathways.
Some of these inducers may be related to dietary components.

We are in a unique position to dissect this link among DCC, mucin synthesis
and cell differentiation since we have initiated detailed studies on the
mechanisms of regulation of the MUC2 gene, the gene which encodes the
principal colonic mucin peptide backbone. We have now cloned, mapped and
partially sequenced approximately 90 kilobases of the locus on chromosome
II encompassing the MUC2 gene and its promotor and enhancer, and have found
this contig contains another mucin backbone gene, probably MUC5b, which is
also expressed in colonic cells both in vivo and in vitro, that could be
coordinately regulated with MUC2.

We will investigate the interaction between DCC and MUC2 expression at the
RNA and protein level, as well as the elaboration and secretion of mucus
and growth parameters. Colonic carcinoma cell lines which have deleted at
least one copy of DCC will be used as recipients of expression vectors
which contain the entire wild-type DCC cDNA, or which encode specific
extracellular and intracellular domains of the DCC protein, and the
influence on constitutive and inducible MUC2 expression determined. The
experiments will be extended to mucin synthesis and secretion, since we
have demonstrated that expression of the gene does not necessarily lead to
production and secretion of mature mucins. Further, different promotor
constructs will be used to define the relationship between specific levels
of DCC expression and cell and molecular phenotype. The promoter and
enhancer for MUC2 will be dissected to delineate sequence elements and
their boundaries necessary to establish responsiveness of MUC2 to DCC.
Finally, we will investigate this relationship of mutations in the promotor
of the MUC2 gene to the sub-class of colonic carcinomas having a mucinous
phenotype.

These experiments will provide detailed understanding of the interaction of
a gene important in the differentiation and transformation of colonic
epithelial cells with the principal hallmark of differentiation along one
lineage. In addition, since mucinous colonic tumors in which MUC2 is
deregulated exhibit a poorer prognosis than most common colorectal tumors,
understanding this interaction may define prognostic factors which are not
reflected in tumor histology or pathology.
StatusFinished
Effective start/end date6/1/963/31/02

ASJC

  • Genetics
  • Cell Biology

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