INDUCTION AND NUCLEAR TRANSLOCATION OF THIOREDOXIN BY OXIDATIVE DAMAGE IN THE MOUSE KIDNEY - INDEPENDENCE OF TUBULAR-NECROSIS AND SULFHYDRYL DEPLETION

Adult T-cell leukemia-derived factor (ADF), originally defined as an i nterleukin-2 receptor inducer, is a human thioredoxin (TRX). ADF/TRX i s a conserved multifunctional reductant presumably associated with red ox regulation of the cellular environment; it works in vitro as a cyto kine, free radical scavenger, activator of transcription factors, and substrate for several enzymes. In the present series of experiments, w e studied the expression and intracellular localization of ADF/TRX in mouse kidney from two different renal tubular injury models: a free ra dical-associated model with ferric nitrilotriacetate (Fe-NTA) and a fr ee radical-independent model with HgCl2. Markers of oxidative damage, such as 8-hydroxy-2'-deoxyguanosine, thiobarbituric acid-reactive subs tances, and 4-hydroxy-2-nonenal-modified proteins, were significantly increased in kidney from male C57BL/6 mice 1 hour after a single intra peritoneal injection of Fe-NTA (5 mg iron/kg). However, in kidney from mice given a subcutaneous injection of HgCl2 (5 mg Hg/kg), none of th ese markers were increased, despite tubular necrosis with sulfhydryl d epletion. In the Fe-NTA model only, Northern and Western blot analyses of the kidney revealed induction of ADF/TRX (> 2.5-fold) after 16 hou rs and translocation of ADF/TRX from the cytoplasmic to nuclear fracti on (> 3.5-fold) after 24 hours. Immunohistochemistry showed a patchy d istribution of ADF/TRX in the normal renal proximal tubules. in ex viv o experiments using serial normal kidney frozen sections, it was found that renal proximal tubules with low expression of ADF/TRX were more vulnerable to oxidative stress mediated by Fe-NTA. Collectively, these data suggest that: (a) ADF/TRX is induced and translocated to nuclei by oxidative damage mediated by Fe-NTA in the renal proximal tubules; (b) induction of ADF/TRX is independent of tubular necrosis or sulfhyd ryl depletion; and (c) ADF/TRX is involved in the cellular defense mec hanisms in vivo against oxidative damage.