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. 2020 Sep 21;9:e55589. doi: 10.7554/eLife.55589

Figure 3. Apelin signaling promotes the sprouting behavior of ECs.

(A) Experimental design: At the blastula stage, cells from Tg(kdrl:HsHRAS-mCherry) embryos were transplanted into host embryos obtained from Tg(fli1a:EGFP) aplnra +/-; aplnrb +/- incrosses. At 24 hpf, the mosaic embryos were imaged and the donor-derived ECs scored for their position. (B, C) 34,5% of wild-type donor-derived ECs in wild-type hosts were found within the ISVs. 80% of wild-type donor-derived ECs in aplnra +/-; aplnrb -/- hosts were found within the ISVs. Notably, wild-type ECs transplanted into aplnr- deficient embryos completely substituted for the lack of cells in the dorsal part of the vasculature at 54 hpf (Figure 3—figure supplement 2). Scale bars: B, 20 µm.

Figure 3.

Figure 3—figure supplement 1. Overexpression of PTX phenocopies loss of Apelin signaling.

Figure 3—figure supplement 1.

Confocal projection images of the trunk region of Tg(kdrl:HsHRAS-mCherry) embryos at 24 hpf. PTX was overexpressed by injecting a bidirectional fli1a promoter driving PTX and GFP at the same time. ECs expressing PTX were detected only in the DA while mCherry expressing control ECs were also detected in the ISVs. Scale bar: 20 µm.
Figure 3—figure supplement 2. Apelin signaling functions cell-autonomously in ECs.

Figure 3—figure supplement 2.

Confocal projection images of the trunk region of Tg(fli1a:EGFP) embryos at 54 hpf. At the blastula stage, cells from Tg(kdrl:HsHRAS-mCherry) embryos were transplanted into host embryos obtained from Tg(fli1a:EGFP) aplnra +/-; aplnrb +/- incrosses. At 54 hpf, the mosaic embryos were imaged and the donor-derived ECs scored for their position. Notably, wild-type ECs transplanted into aplnr deficient embryos completely substituted for the lack of cells in the dorsal part of the vasculature at 54 hpf (Figure 3—figure supplement 1). Scale bar: 30 µm.