Figure 1

Hypoxia potentiated Notch1 signalling via stabilization and activation of transcription factor HIF-1α. Expression of components of the HIF-1α and Notch1 signalling pathways at the mRNA (A) and protein (B) levels in Jurkat and Sup-T1 cells cultured under hypoxic conditions for 48 h. (A) Results normalized to β-Actin are calibrated to a normoxic control and presented as relative mRNA expression level. *, P < 0.01. (B) N, normoxia group; H, hypoxia group. Results shown are representative of at least three independent experiments. (C) Notch1-luciferase-transfected Jurkat cells had significantly greater reporter gene activity when incubated in hypoxic conditions for 48 h than in normoxia. Results are calibrated to normoxic control. RLU, relative light units. *, P < 0.01. Components of the HIF-1α and Notch1 signalling pathways were assayed by qRT-PCR (D) and Western Blot (E) to determine the effect of knocking down HIF-1α or Notch1 expression in hypoxia. Notch1 signalling was inhibited by HIF-1α blockage, whereas HIF-1α expression was not affected by Notch1 suppression. HS, HIF-1α siRNA-transfected group; NS, Notch1 siRNA-transfected group; CS, control siRNA-transfected group. *, P < 0.01.