PARENT SESSION
41 - Physiological and Molecular Mechanisms of Toxicity
8:00 AM to 6:30 PM, Tuesday, 14 May 2002
Exhibition Area

(41-27) Modulation of galectin 1 and thioredoxin peroxidase II expression by sodium arsenite in Chinese hamster ovary cells.

Huang, Rong-Nan^*,1, Lee, Te-Chang², Chang, Kwang-Ning¹, Tam, Ming-F³, ¹ Department of Life Sciences, National Central University, Chungli, Taoyuan, Taiwan, R. O. C.² Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C.³ Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, R.O.C.

ABSTRACT- Arsenic is a ubiquitous environmental carcinogen, and its toxic mechanism are not fully illustrated. In this study, we report the identification of two proteins modulated by arsenite treatment in Chinese hamster ovary (CHOA) cells. The crude extract from CHOA and SA7 (an arsenic resistant CHOA cells) cells was applied onto an phenylarsine oxide-agarose (PAO-agarose) affinity column, and after extensive washing, the absorbed proteins were eluted with buffers containing 20 mM 2-mercaptoethanol (2-ME) or dithiothreitol (DDT). Three over-expressed proteins, galectin I (in the 2-ME eluted fraction from CHOA cells), glutathione S-transferase (GST) and thioredoxin peroxidase II (respectively in the 2-ME and DDT eluted fraction from SA7 cells) were identified by SDS-polyacrylamide gel and partial amino acid sequence analysis. The GST protein has previously been shown to facilitate the excretion of arsenite from SA7 cells. Thioredoxin peroxidase II was over-expressed only in SA7 cells (routinely cultured in arsenite-containing medium), but not in CHOA or SA7N (a revertant of SA7 cells cultured in drug-free medium) cells, and galectin I was specifically identified in CHOA and SA7N cells, but not in SA7 cells. The preferential expression of galectin I in CHOA cells and thioredoxin peroxidase II in SA7 cells was further illustrated by quantitative PCR analysis. These results suggest that expression of the two proteins can be modulated by arsenite treatment in CHOA cells. In addition, we also cloned, for the first time, the cDNA of thioredoxin peroxidase II from SA7 cells. The galectin-1 plays important role in cell proliferation and apoptosis, and thioredoxin peroxidase II functions as an antioxidant enzyme. The role of galectin-I and thioredoxin peroxidase II in arsenite-induced toxicity deserves further study.

Key words: sodium arsenite, galectin-1, thioredoxin peroxidase-II