Related Experiment Videos
Developmental regulation of cryptdin, a corticostatin/defensin precursor mRNA in mouse small intestinal crypt
A J Ouellette1, R M Greco, M James
1Cell Biology Unit, Shriners Burns Institute, Boston, Massachusetts.
Insights
Cryptdin mRNA, found in mouse intestinal crypts, codes for a peptide involved in development. Its expression increases with age, peaking in adulthood, independent of T cells and bacteria.
Area of Science:
- Molecular Biology
- Developmental Biology
- Gastroenterology
Background:
- Cryptdin mRNA encodes a precursor to a corticostatin/defensin-related peptide.
- This peptide accumulates in mouse intestinal crypt epithelium during postnatal development.
Purpose of the Study:
- To determine the primary structure, intestinal cell distribution, and developmental appearance of cryptdin mRNA.
- To investigate the factors influencing cryptdin mRNA levels in adult small intestine.
Main Methods:
- In situ hybridization of cryptdin cDNA to mouse jejunum and ileum sections.
- Analysis of cryptdin mRNA expression in mice at different postnatal ages (10, 16, 20 days, and older).
Main Results:
- Cryptdin mRNA is 450-480 nucleotides long, with a 70-amino acid open reading frame sharing features with defensins and corticostatins.
- Expression is localized to epithelial cells at the base of intestinal crypts.
- mRNA levels increase significantly from 10 days to adulthood, reaching maximal levels by the fourth week.
Conclusions:
- Cryptdin mRNA expression is developmentally regulated in the mouse small intestine.
- Adult cryptdin mRNA levels are not influenced by T cells or luminal bacteria.
- The precise physiological role of cryptdin in the small bowel requires further investigation, with potential roles in bacterial inhibition or hormone modulation.
Abstract:
Cryptdin mRNA codes for the apparent precursor to a corticostatin/defensin-related peptide that accumulates to high levels in mouse intestinal crypt epithelium during postnatal development. The primary structure, intestinal cell distribution, and developmental appearance of cryptdin mRNA have been determined. Cryptdin mRNA is 450-480 nucleotides long. Translation of the partial cryptdin cDNA sequence reveals a 70-amino acid open reading frame that includes 32 carboxy-terminal residues that align with those in the consensus sequence, C.CR...C....ER..G.C....CCR, which is a common feature of leukocyte defensins and lung corticostatins (Selsted, M. E., D. M. Brown, R. J. DeLange, S. S. L. Harwig, and R. I. Lehrer. 1985. J. Biol. Chem. 260:4579-4584; Zhu, Q., J. Hu, S. Mulay, F. Esch, S. Shimasaki, and S. Solomon. 1988. Proc. Natl. Acad. Sci. USA. 85:592-596). In situ hybridization of cryptdin cDNA to paraformaldehyde-fixed, frozen sections of adult jejunum and ileum showed intense and specific labeling of epithelial cells in the base of all crypts. Analysis of sections from suckling mice showed that cryptdin mRNA is detectable in 10-20% of crypts in 10-d-old mice, in approximately 80% of crypts in 16-d-old mice, and in all crypts of mice 20 d and older. During the fourth week, the sequence accumulates in crypts to the maximal adult level. Cryptdin mRNA content in adult small intestine is independent both of T cell involvement and luminal bacteria. The role of cryptdin in small bowel physiology remains to be determined: cryptdin may inhibit bacterial translocation, modulate intestinal hormone synthesis, influence hormonal sensitivity of the intestinal epithelium, or exhibit a multiplicity of related activities.