Figure 2.

Down-regulation of claudins-2 and -12 in the ileum and colon of VDRKO mice. (A) Gene expression of claudin-2 (Cldn2) and Cldn12 in the colon of wild-type (+/+; lanes 1–3) and VDRKO mice (−/−; lanes 4–6) at 12 wk of age. One microgram of total RNA from the jejunum was subjected to RT-PCR analysis for the indicated genes. PCR was performed for 20 (36B4), 23 (Cldn2), or 36 (Cldn12 and VDR) cycles. (B) RT-PCR analysis was performed as described in A for at least four independent experiments. The mRNA levels are normalized to the corresponding 36B4 levels and expressed relative to the amount present in the wild-type mice, which was taken as 100. Values represent the mean ± SD (error bars; n = 4 for Cldn12 and n = 6 for Cldn2). (C) Expression of Cldn2 and Cldn12 proteins in the ileum of each genotype at 12 wk of age. Twenty-five micrograms of whole cell extract from the ileum was separated by SDS-PAGE and immunoblotted with the corresponding antibodies followed by chemiluminescence detection. Each blot was stripped and reimmunoprobed with an anti-actin antibody. (D) Western blot analysis was performed as described in C for at least five independent experiments. The protein levels are normalized to the corresponding actin levels and expressed relative to the amount present in wild-type mice, which was taken as 100. Values represent the mean ± SD (error bars; n = 5 for Cldn2 and n = 8 for Cldn12).