Studies of cloning, characterization, tissue expression and regulation by retinoic acid
Subsequent Statement of Responsibility
M. C. Rose
.PUBLICATION, DISTRIBUTION, ETC
Name of Publisher, Distributor, etc.
The George Washington University
Date of Publication, Distribution, etc.
1997
PHYSICAL DESCRIPTION
Specific Material Designation and Extent of Item
194
DISSERTATION (THESIS) NOTE
Dissertation or thesis details and type of degree
Ph.D.
Body granting the degree
The George Washington University
Text preceding or following the note
1997
SUMMARY OR ABSTRACT
Text of Note
Mucus is a viscoelastic gel-like component that protects and lubricates mammalian epithelia. The major component of mucus is a family of glycoproteins known as mucins which are heavily glycosylated, large molecular weight molecules that contribute to the viscosity of mucus. Their protein backbones are encoded by mucin genes. In order to identify the mucin gene that encoded tracheobronchial mucin (TBM), a nasal polyp cDNA library was generated and screened with a unique nucleotide probe that encoded the TR-3A peptide sequence of TBM. A 3567 bp clone, NP3a, was identified and shown to encode the usd3\primeusd end of the MUC5 gene. It encodes a five amino acid repeat unit tandemly repeated five times and two octapeptides that are conserved among several human and animal secretory mucin genes. The NP3a gene was localized to chromosome 11. To obtain additional information about the structure of MUC5, a 34 kb genomic MUC5 clone, CRIE1, was subjected to restriction digestion. An EcoRI/XhoI 5.5kb fragment was subcloned and sequenced revealing almost perfect identity with 650bp located at the extreme usd3\primeusd end of clone NP3a. The regulation of MUC5 expression by retinoic acid was examined in vitro using A549 cells, a lung carcinoma cell line. MUC5 expression was shown to be increased in both a time and dose-dependent manner. MUC5 regulation was also investigated in vivo using a hamster model. A 534bp hamster Muc-5 homologue was isolated from hamster stomach cDNA by RT-PCR and subcloned. Sequence analysis revealed a high degree of homology between the human MUC5 and rat Muc-5. Using the hamster cDNA clone as probe, Northern blot analysis revealed an increase in Muc-5 expression in RNA isolated from the gastro-intestinal tract and trachea of Golden Syrian hamsters fed a diet enriched in retinoic acid. Northern blot analysis demonstrated that both human MUC5 and hamster Muc-5 showed high levels of gene expression in stomach. In addition, NP3a showed a significant degree of MUC5 expression in upper respiratory tract tissue.