Extended Data Figure 9. Age-dependent endothelial HIF1-α expression.
a, Representative confocal images showing HIF1-α (green) and CD31 (red) immunostaining on sections of 2 week-old tibia. Nuclei, DAPI (blue). Note abundance of HIF1-α-positive type H ECs in 2 week-old metaphysis (mp) but not in the type L endothelium in diaphysis (dp). Dashed line marks border of growth plate (gp).
b, Quantitative mRNA expression analysis of Hif1a transcripts relative to mRNA encoding β-actin in type H and type L. Data represent mean±s.e.m (n=3 biological replicates). P values, two-tailed unpaired t-test.
c, d, Maximum intensity projections of HIF1-α (green) and CD31 (red) immunostaining in 7 week-old (c) and 61 week-old (d) tibiae. Nuclei, DAPI (blue). HIF1-α-positive endothelium was not detected in metaphysis (mp) of 7 week-old (c) and 61 week-old tibia (d).
e, Maximum intensity confocal images from the diaphysis of 5 week-old Flk1-GFP (green) irradiated (900 rads) and control tibiae after HIF1-α (red) immunostaining. HIF1-α signals (arrowheads) in GFP+ ECs are enhanced after irradiation.
f, qPCR expression analysis of Hif1a relative to transcripts encoding β-actin in sorted ECs from bones of irradiated mice and untreated controls. Data represent mean±s.e.m (n=7 mice from three independent experiments). P values, two-tailed unpaired t-test.