Figure 3

Cubilin expression in the intestine of Cubn^{+/del exon 1–6;EGFP}mice. A-C show images of EGFP fluorescence in the luminal surface of whole mount segments of the duodenum (A), jejunum (B) and ileum (C) from a Cubn^{+/del exon 1–6;EGFP} mouse. Inset panel c’ shows a segment of the ileum from a wildtype mouse subjected to epifluorscent imaging as in A-C. D shows an immunoblot analysis of detergent extracts of segments of the intestine and kidney using antibodies to cubilin, megalin, amnionless (Amn), intrinsic factor (IF) and tubulin. E is a DIC image of the luminal face of the small intestine (ileum) from a Cubn^{+/del exon 1–6;EGFP} mouse. F is an epifluorescence image showing EGFP fluorescence in the epithelial cells of the intestinal villi shown in E. Note the mosaic pattern of cubilin-EGFP fluorescence. G is a cross section of the small intestine from a Cubn^{+/del exon 1–6;EGFP} mouse showing cubilin-EGFP expression in patches of villi. H is a high magnification view of a cluster of villi showing segmental cubilin-EGFP expression in epithelial cells within individual villi. I is a qPCR analysis of cubilin and EGFP mRNA levels in microdissected intestinal villi segments (n=4 mice) that were either predominantly EGFP-positive, negative or both. Asterisks indicate that mRNA levels measured in EGFP-positive or EGFP-negative villi isolates were significantly different (p<0.05) from the levels in RNA prepared from villi containing both EGFP-positive and EGFP-negative cells. Pound signs indicate that mRNA levels measured in EGFP-positive villi were significantly different (p<0.05) from levels in EGFP-negative villi.