FIGURE 5.

Differential regulation of HIF-1α hydroxylation sites during hypoxic induction and during re-oxygenation. A, reoxygenation. RCC4 cells, incubated in Lumox dishes in normoxia (Nx) or hypoxia (Hx; 0.1% oxygen) for 4 h, were then exposed to normoxia for the indicated times. Hydroxylation at Hyp564 and HyAsn⁸⁰³ is complete within 1 min, but delayed at Hyp402. B and C, induction of HIF-1α by hypoxia. HeLa or HT1080 cells were incubated in normoxia or hypoxia (1 or 3% oxygen) for the indicated times (h). Immunoblots were probed with the indicated antibodies. During the accumulation of HIF-1α in hypoxic cells, substantial hydroxylation at Hyp564 but not Hyp402 is observed, particularly in HeLa cells.