The structure of human intestinal apomucins

Area of Science:

• Molecular biology
• Gastroenterology
• Cancer research

Background:

• Human intestinal mucins are large protective glycoproteins coating the epithelium.
• Mucins are frequently altered in cancer, indicating potential as tumor markers.

Purpose of the Study:

• To isolate and characterize mucins from human colon cancer cells (LS174T) and small intestine.
• To identify and analyze the genetic makeup of different apomucins involved in gastrointestinal function and disease.

Main Methods:

• Isolation of mucins from LS174T cells and small intestine.
• Deglycosylation of purified mucins.
• Production of polyclonal antibodies against apomucins.
• Isolation of cDNA clones encoding MUC2 and MUC3 mucins using antibody-based screening.
• Northern blot analysis to assess gene expression and size.
• Chromosomal localization of MUC2 and MUC3 genes.

Main Results:

• Two distinct mucin cDNAs, MUC2 and MUC3, were isolated, encoding different apomucins.
• MUC2 contains 69 tandem repeats encoding a threonine- and proline-rich peptide; its gene is on chromosome 11.
• MUC3 has 51 tandem repeats encoding a threonine- and serine-rich peptide; its gene is on chromosome 7.
• Both MUC2 and MUC3 are expressed in colonic tumors, but at variable levels.

Conclusions:

• At least two distinct mucins, MUC2 and MUC3, are expressed in the human gastrointestinal tract.
• The variable expression of MUC2 and MUC3 in colonic tumors highlights their potential as cancer markers.
• Understanding the regulation of MUC2 and MUC3 is crucial for comprehending intestinal physiology and pathophysiology.