Cldn3 up-regulation requires transcriptionally active rather than junctional β-cat in MBEs in vitro. (A, a–c; and B, a) MBEs were either treated with Wnt3aCM or control CM and infected with dnTCF4 adenovirus or a control. (A, a–c) IF stainings for Cldn3. dnTCF4 abrogated the effect of Wnt3aCM on junctional Cldn3. (B, a) Quantitative RT-PCR for Cldn3 (n = 3; **, P = 0.0095), Plvap (n = 3; *, P = 0.035), and Axin2 (n = 3; **, P = 0.004) with Wnt3aCM and for Plvap (n = 3; **, P = 0.002) with Wnt3aCM and dnTCF4. (A, d; and B, b) MBEs infected with LefΔN-βCTA lentivirus or a control. Junctional localization of Cldn3 increased in IF stainings. Quantitative RT-PCR for Cldn3 (n = 3; **, P = 0.002), Plvap (n = 3; **, P = 0.008), and Axin2 (n = 3; **, P < 0.0001). Controls are set as 100% (dashed lines). Green nuclei show an anti–V5-TAG (c) and an anti–HA-TAG (d) staining of dnTCF4 and LefΔN-βCTA, respectively, confirming infection of the target cells. Error bars represent SEM.