Positional specificity of defensin gene expression reveals Paneth cell heterogeneity in mouse small intestine

Paneth cell defensins are antimicrobial peptides expressed by these cells in the intestinal epithelium. In a study of Paneth cell defensin cryptdins, it was shown that gene expression of the cryptdin-4 isoform varies along the proximal-to-distal intestinal axis, with expression at its highest in the ileum. In contrast, level of expression of cryptdin-1 and -5 were consistent in other parts of the small intestine. These results suggest that the position of the defensin gene may determine Paneth cell differentiation.