Fig. 7

Loss of LRE Function Results in Growth Stunting and Intestinal Swelling in Suckling Mice

(A and B) Confocal images of LREs of TgBAC(cldn15la-GFP ^pd1034)zebrafish larva (A) and of P7 neonatal mouse (B) after mCherry uptake. Arrows point to lysosomal vacuoles filled with mCherry. Dashed line in (B) indicates basement membrane. Scale bar, 10 μm.

(C–F) Confocal images of LREs (C and D) and IECs (E and F) of TgBAC(cldn15la-GFP ^pd1034); TgBAC(lamp2-RFP ^pd1044) zebrafish larva and P7 neonatal mouse intestine stained with LAMP2 antibody, showing the presence of lysosomal vacuoles (arrows) in LREs (C and D) and lysosomes (arrowheads) in IECs (E and F). Scale bar, 10 μm.

(G) Confocal images of duodenum and ileum of P6 neonatal mouse after mCherry uptake. Arrowheads point to small vesicular structures with mCherry in IECs and arrows point to lysosomal vacuoles filled with mCherry in LREs. Scale bar, 10 μm.

(H) DAB2 expression in the duodenum, jejunum, and ileum of P3 WT neonatal mouse. DAB2 expression is enriched in the ileum (arrowheads), the segment harboring LREs. Scale bar, 10 μm.

(I) mCherry uptake in the ileum of P6 Dab2 WT and Dab2 cKO (Vil1-Cre;Dab2^tm1Cpr fl/fl) mice. While DAB2 expression (top images; arrowheads) and mCherry protein uptake (middle images; arrows) is abolished in Dab2 cKO mouse ileal LREs, LAMP2 expression is not (bottom images; arrows). Scale bar, 5 μm.

(J) Images of P22 Dab2 WT and Dab2 cKO mice.

(K–N) Quantitation of body length (K), weight (L), average weight gain/day (M), and duodenum diameter (N) of P22 Dab2 WT and cKO mice.

(O) Images of dissected duodenum of P22 Dab2 WT and cKO mice. Brackets show prominent swelling of the GI tract in Dab2 cKO mice. Scale bar, 1 cm.

(P) Images of the dissected stomach and intestinal tract of WT and Dab2 cKO mice harvested at P22. Scale bar, 1 cm.

(Q) Images of H&E stained sections of the duodenum of P22 Dab2 WT and cKO mice, which exhibit severe distended villi (arrowheads and asterisk) indicative of submucosal edema. Scale bar, 500 μm (transverse cross sections), 100 μm (longitudinal cross sections).

(R) Hematoxylin and periodic acid–Schiff (PAS) staining of duodenal sections of WT and Dab2 cKO P22 mice. Concave arrowheads point to Paneth cells within crypts; flat arrowheads show goblet cells; arrows mark apical membrane; asterisks indicate edema. Scale bar, 200 μm (left), 40 μm (middle), and 20 μm (right). In (K–N), data points are littermate averages for each genotype and littermate averages of WT and cKO from the same litter are paired with lines. Measurements of individual mice from 8 different litters graphed in (K–N) are provided in the Table S2. ^∗p < 0.05; Two-tailed paired t tests (K–N). p values, t values, and degree of freedom for the statistical tests are provided in Table S3.