Lack of reelin modifies the gene expression in the small intestine of mice

We recently demonstrated that the mucosa of the small intestine of the rat expresses reelin and some components of its signaling system. The current study evaluates whether reelin affects the intestinal gene expression profile using microarray analysis and reeler mice, a natural mutant in which reelin is not expressed. The effect of the mutation on body weight and intestinal morphology is also evaluated. The mutation reduces body and intestinal weight during the first 2 months of age and modifies the morphology of the crypts and villi. For the microarray assays, total RNA was obtained from either isolated epithelial cells or intact small intestine. Of the 45,101 genes present in the microarray the mutation significantly alters the expression of 62 genes in the isolated epithelial cell samples and of 84 in the intact small intestine. The expression of 83% of the genes tested for validation was substantiated by reverse transcriptase polymerase chain reaction. The mutation notably up-regulates genes involved in intestinal metabolism, while it down-regulates genes related with immune response, inflammation, and tumor development. Genes involved in cell proliferation, differentiation, apoptosis, membrane transport and cytoskeleton are also differently expressed in the reeler mice as compared with the control. This is the first report showing that the lack of reelin modifies intestinal morphology and gene expression profile and suggests a role for reelin in intestinal epithelium homeostasis.