Fig. 4.

Prox1 expression is regulated in the small intestine by Fiaf. (A) qRT-PCR analysis of the relative expression of Fiaf in the small intestine of wild-type E18–P24 mice (n = 4 per group, each intestine analyzed individually; mean values ± SE are plotted relative to E18). ∗, P < 0.05; ∗∗, P < 0.01. Control experiments showed that Fiaf expression remains constant in the liver during this period (data not shown). (B) Expression of Prox1 in the small intestines of Fiaf+/+ and Fiaf−/− littermates (n = 4 per group, each intestine analyzed individually; mean values ± SE are plotted relative to E18; note that Fiaf−/− mice do not survive to P24, so no data are shown for this time point). ∗∗∗, P < 0.001 compared with wild type. (C–F) Multilabel immunofluorescence study demonstrating Prox1-positive nuclei (yellow) in Lyve-1-positive small intestinal lymphovascular endothelium (red). In wild-type mice (C and D), nearly all lymphatic endothelial cell nuclei are Prox1-positive, whereas in Fiaf−/− mice (E and F), >90% are Prox1-negative (arrowheads). The arrows in E and F point to a rare Prox1-positive lymphatic endothelial cell nucleus within the Fiaf−/− small intestine. (Scale bars: 50 μm.)