Inducible deletion of PCBP1 specifically in the intestinal epithelium of mouse. (A) Relative levels of PCBP1 mRNA in IECs and livers in PCBP1^fl/fl (WT) vs PCBP1^ΔIEC (ΔIEC) mice. Weanling mice were fed a tamoxifen diet for 1 month before analysis. mRNA levels from IECs of proximal duodenum were determined by real-time quantitative polymerase chain reaction (qPCR). (B) Detection of PCBP1 in all cells throughout the duodenum of WT mice. Fixed, embedded sections of proximal duodenum analyzed by anti-PCBP1 immunohistochemistry. Brown stain indicates PCBP1. Arrows: epithelial cells. Brackets: duodenal crypts. (C) Specific deletion of PCBP1 in duodenal epithelium of ΔIEC mice. PCBP1 detected by IHC as in panel B, above. Note the absence of brown PCBP1 signal in crypts and epithelial layer with PCBP1 expression in lamina propria and duodenal wall. (D) Absence of PCBP1 protein in immunoblot of IECs from PCBP1^ΔIEC mice. IECs were collected and analyzed by immunoblotting for PCBP1 and PCBP2. Representative blot shown on the left, quantitation on the right. (E) Increased villus length and crypt depth in PCBP1^ΔIEC mice. Intact, full-length villi and crypts were measured in hematoxylin and eosin–stained sections of duodenum. Mean lengths of structures 1 cm distal to pylorus calculated from each animal; 5 age-matched WT and PCBP1^ΔIEC mice were analyzed. Refer to female mice data in supplemental Figure 1.