Thioredoxin: Inducible radioprotective protein by low-dose radiation

Thioredoxin (TRX), that has many biological activities, is radioprotector and a key protein in regulating cellular functions through redox reaction. We observed time course and dose dependent alteration of TRX gene expression in human peripheral lymphocytes after low-dose irradiation. TRX mRNA level increased to a peak, 5.7-fold higher than the control at maximum, 6 h after irradiation, and then decreased. The optimum radiation dose for enhancement of induction of the TRX mRNA was 0.25 Gy. The TRX protein, also increased to a peak, a 3-fold increase at maximum, with the same timing as that for TRX mRNA. Induction of the expression of TRX gene mess followed after ionizing irradiation of lymphocytes from human donors. The similarity of time course between TRX gene expression and induction of radioadaptive response by low-dose radiation suggests that TRX may be involved in adaptive response. (author)