Figure 1: Differential Nrp1 levels affect tip cell competition.
From: Alk1 and Alk5 inhibition by Nrp1 controls vascular sprouting downstream of Notch
(a–c) Retinal vessels from a wild-type host expressing DsRED injected with Nrp1Lacz/+ ES cells, assayed at postnatal day P5. (a) Representative overview of the sprouting front; scale bar, 420 μm. (b) Segmented images showing wt nuclei (white) and nuclei from Nrp1lacZ/+ cells (green), using Erg staining; scale bar, 20 μm. (c) Quantification of tip cell contribution normalized to overall contribution of cells to the endothelium, P<0.0001 compared with wt cells injected retinas. (d–i) Retinas of Nrp1fl/fl; mTmG; Cdh5-CreERT2 and Nrp1fl/+; mTmG; Cdh5-CreERT2 mice injected with 30 μg tamoxifen at P1, retinas were assayed P5. (d,g) Representative overview of the sprouting front, scale bar, 100 μm, and higher magnification, scale bar, 20 μm (e,h). Unrecombined, wt cells are labelled with Isolectin-B4 only; recombined Nrp1-deficient cells express GFP. (f,i) Quantification of recombined Nrp1-deficient cells at the tip, normalized to overall contribution of cells to the endothelium. Statistical significance was determined by comparing the proportion of Nrp1-deficient (green) cells at the tip with the total proportion of Nrp1-deficient cells; P<0.001 (f), P<0.0015 (i). n=the number of retinas analysed; n=4 (c), n=3 (f) and n=6 (i). Values represent mean±s.e.m. Statistical significance was assessed using a Student’s unpaired t-test.
