Figure 2. Deletion of Arrb1 attenuates the VEGF-C/VEGFR3 signaling in mice exposed to hypoxia.

(a) Heat map showing differential expressed genes at false discovery rate (FDR, Arrb1 KO mice subjected to hypoxia (n = 3 mice per group). Vegfc expression is pointed by a red arrow. (b) Decreased mRNA expression by RNA-seq of Vegfc, Lyve1 and vwf in the lung of Arrb1 KO compared to WT mice exposed to hypoxia. Statistical analysis was performed by CuffDiff. (c) RT-qPCR mRNA expression of Vegfc, Lyve1 and Vegfb in the lungs of WT, Arrb KO, and Arrb2 KO mice subjected to normoxia or hypoxia (n = 3 mice per group). (d) Protein expression in lung lystates from WT, Arrb1 KO, and Arrb2 KO mice (n = 3 mice per group). Quantification and normalization to WT exposed to normoxia demonstrates (e) a significant decrease in VEGFR3 and Akt phosphorylation in Arrb1 KO mice. Statistical analysis was performed by one-way ANOVA and Tukey's multiple comparison test. (f) Loss of VEGFR3 in IPAH lung sections stained for LYVE1 (green), VEGFR3 (red), and nuclei (Hoechst; blue). Scale bar = 50 μm. (g) Inhibiting VEGFR3 signaling by the VEGFR3 inhibitor MAZ51 exacerbates PAH in WT mice (n = 8 mice per group), but not Arrb1 KO mice (n = 9 mice per group). Statistical analysis was performed by two-tailed unpaired t test. *, p < 0.05; ***, p < 0.001.