Regulation of protein synthesis in human cells exposed to extreme hypoxia.

Protein synthesis was recorded in NHIK 3025 cells when cultured either during extremely hypoxic conditions or following reoxygenation. The rate of total protein synthesis in NHIK 3025 cells was found to be reduced to 30-40% of the rate in control cells within 1 h after the start of hypoxia. After reoxygenation, the rate of total protein synthesis was found to increase rapidly back to the control level. To reveal the stage of regulation of hypoxia associated proteins (HAP), mRNA was isolated from NHIK 3025 cells and translated in an in vitro translation kit. The results indicated that the relative amount of mRNA, of at least two HAP (80 and 45 kD), was increased under extremely hypoxic conditions ([O2] < 4ppm). This implies that some HAP are regulated pre-translationally.