Figure 7.
The tln1 gene is essential for endothelial tube formation in both the SIV plexus of zebrafish embryos and HUVECs. A–C) The vessel lumen of the SIV plexus (red arrows) was hardly detectable in tln1fl02k mutants (B) compared with WT siblings (A) and tnnt2a morphants (C) in Tg(kdrl:EGFP) transgenic embryos at 72 hpf. n, number of hearts. D–G) Vessels with lumens were barely formed by HUVECs treated with TLN1 siRNAs (E) compared with control siRNA (D) after culture in 3D collagen matrices for 24 h. D) Arrows: representative endothelial tube structures with an open lumen lined by flat endothelial cells, which are lacking in TLN1-deficient HUVECs (E). F) Statistics for endothelial cell (EC) tubes in (D, E), where the areas of the lumens were traced. Data are mean luminal areas ± sd (n = 3). **P < 0.01 vs. luciferase control. G) HUVEC extracts were prepared for Western blot analysis and probed for anti-Tln1 and anti-actin control. siRNA efficiently knocked down Tln1. Scale bars, 100 μm (A–C); 50 μm (D, E).