Expression and Significance of HIF-3α in Mitochondria

  Objective  To investigate the mitochondrial translocation of hypoxia inducible factor-3α (HIF-3α) under normoxia and hypoxia and its physiological and pathological meanings.

  Methods  ① After hypoxic (1%O₂) or DMOG, CoCl₂ treatments mimicking the hypoxic treatment, Western blot and immunofluorescence were used to examine the HIF-3α expression in mitochondria of HeLa and ACHN cells, respectively. ②The protease sensitivity experiment was used to explore the sub-organelle localization of HIF-3α in mitochondria. ③Western blot was used to examine mitochondrial HIF-3α in the normal mouse tissues and human liver carcinoma tissues.

  Results  ① In HeLa and ACHN cells, HIF-3α translocated to mitochondria under normoxia and hypoxia, and its mitochondrial expression was higher under hypoxia; ②The protease sensitivity of HIF-3α was similar to proteins locating in the mitochondrial outer membrane; ③Mitochondrial HIF-3α expressed in multiple normal mouse tissues; The expression of mitochondrial HIF-3α was higher in human liver carcinoma tissues than the normal and adjacent tissues.

  Conclusion  HIF-3α translocated to mitochondrial outer membrane under both normoxia and hypoxia, and hypoxia could up-regulated HIF-3α mitochondrial translocation. Meanwhile, the phenomenon may be involved in the process of liver carcinoma.