Figure 1.

MiR-152 is a predominant hypoxia-responsive miRNA. (A) Western blot showing the effects of hypoxia and HIF-1α siRNA on the expression of HIF-1α. (B) qRT-PCR analyses of the expression of candidate miRNAs. HeLa cells treated with scrambled or HIF-1α siRNA (shHIF1α) were cultured for 24 h. One plate of each remained in normoxia while the other was exposed to 2% O₂ for an additional 24 h. RNA was then harvested and used for qRT-PCR analyses. Four miRNAs were upregulated by hypoxia with MiR-152 increasing to the greatest extent. The induction of all four miRNAs was dependent on HIF-1α (*P < 0.05, **P < 0.01) (n = 3). (C) Northern blot (miR-152) and Western blot (HIF1α) analyses showing induction under different levels of hypoxia. HeLa cells were split into four plates 24 h before treatment. One plate was then exposed to either 21%, 2%, 0.5%, or 0.02% oxygen for 24 h. Small nuclear RNA U6 was used as a loading control for the northern blot and β-actin for the Western blot