Conditional β-cat GOF or LOF in ECs in vivo modulates Cldn3 and Plvap expression and permeability in brain capillaries. P14 brain sections of 4OHT-treated LOF mice stained for Cldn3 or Plvap together with IB4. (A, a and g) Cre⁻ control mice. Arrowheads point to Cldn3-positive and Plvap-negative vessels, respectively. (d and j) Cre⁺ LOF resulted in Cldn3 down- and Plvap up-regulation in ∼50% of brain capillaries. Arrowheads point to Cldn3-negative and Plvap-positive vessels, respectively. β-Cat GOF in ECs in vivo by 4OHT treatment. E18.5 and P4 brain sections analyzed for Cldn3 or Plvap (green) together with IB4 (red). (b, c, h, and i) Cre⁻ control mice. Arrowheads point to weak Cldn3-positive vessels at E18.5 and a slightly higher level at P4 or strong Plvap at E18.5 and a slightly weaker level at P4. (e, f, k, and l) Cldn3 increase in Cre⁺ mice at E18.5 and P4. Plvap was down-regulated. Left panels show merge of IB4 and Cldn3 or Plvap; right panels show Cldn3 or Plvap alone in black and white. Insets show higher magnifications. (B) Evans blue injection i.p. 18 h before tissue harvesting in LOF mice. Arrowheads point to extravasated Evans blue in Cre⁺ mice at P14. (C) Quantitative RT-PCR for Plvap at P7 in LOF (n = 3; **, P = 0.0001) and GOF (n = 3; *, P = 0.0382). Cldn3 was statistically NS. Control is set to 100% (dashed line). Error bars represent SEM.