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Cryptdin gene expression in developing mouse small intestine
D Darmoul1, D Brown, M E Selsted
1Gastrointestinal Unit, Massachusetts General Hospital, Boston, USA.
The American Journal of Physiology
|January 1, 1997
Summary
Newborn mice possess Paneth cell defensin mRNAs before crypt development. These defensins are secreted into the lumen, potentially supporting neonatal innate immunity before mature Paneth cells emerge.
Area of Science:
- Gastroenterology
- Immunology
- Developmental Biology
Background:
- Intestinal epithelial cells differentiate postnatally in rodents.
- Paneth cells are key players in intestinal innate immunity, producing antimicrobial peptides.
Purpose of the Study:
- To investigate the presence and localization of Paneth cell defensin mRNAs and proteins in the neonatal mouse intestine.
- To determine if defensin secretion occurs before the full maturation of Paneth cells and crypts.
Main Methods:
- Reverse transcriptase-polymerase chain reaction (RT-PCR) to detect defensin mRNAs.
- Sequencing of RT-PCR products to identify specific defensins.
- Immunohistochemistry and immunofluorescence to localize cryptdin proteins.
Main Results:
- Defensin mRNAs, including abundant cryptdin-6, were detected in 1-day-old mouse intestine prior to crypt formation.
- Cryptdin-positive cells were distributed throughout the neonatal epithelium, not confined to crypts.
- Cryptdins were found within intracellular granules and secreted onto mucosal surfaces, indicating luminal release.
Conclusions:
- Enteric defensins are present and secreted in the neonatal mouse intestine before the establishment of mature Paneth cells.
- Defensin secretion likely contributes to the innate immune defense of the neonatal gut.
- This suggests an early-acting innate immune mechanism in the developing intestine.