A PANETH CELL ANALOG IN XENOPUS SMALL-INTESTINE EXPRESSES ANTIMICROBIAL PEPTIDE GENES - CONSERVATION OF AN INTESTINAL HOST-DEFENSE SYSTEM

Antimicrobial peptides are a widespread component of host defense. We characterized the tissue distribution and cellular localization of expression of the magainin family of antimicrobial peptide genes in Xenopus laevis. Two genes from this family, magainin and PGLa, are expressed at high levels in the skin and throughout the gastrointestinal tract. Magainin and PGLa mRNAs are synthesized in the granular multinucleated cell (GMC) of the gastric mucosa, a cell shown previously to contain magainin and PGLa peptides by immunohistochemical methods. In addition, we have localized magainin and PGLa mRNAs to distinct cells of Xenopus small intestine. Further characterization of this large, granule-filled cell by electron microscopy demonstrates features in common with the Paneth cell of mammalian small intestine, previously identified as a site of expression of antimicrobial peptide genes of the defensin family in mouse and human. Our identification of granule-laden, eosinophilic intestinal cells in Xenopus as a site of magainin and PGLa antimicrobial peptide gene expression suggests that these cells are functional analogues of mammalian paneth cells and further supports a conserved role of antimicrobial peptides in host defense of the vertebrate small intestine.