Effect of Pharmaceutical Potential Endocrine Disruptor Compounds on Protein Disulfide Isomerase Reductase Activity Using Di-Eosin-Oxidized-Glutathion

Mélanie Villeret,Danièle Klett,Cameron Neylon,Yves Combarnous,Claire Cahoreau

doi:10.1371/journal.pone.0009507

Abstract

BackgroundProtein Disulfide Isomerase (PDI) in the endoplasmic reticulum of all cells catalyzes the rearrangement of disulfide bridges during folding of membrane and secreted proteins. As PDI is also known to bind various molecules including hormones such as estradiol and thyroxin, we considered the hypothesis that adverse effects of endocrine-disrupter compounds (EDC) could be mediated through their interaction with PDI leading to defects in membrane or secreted proteins.Methodology/Principal FindingsTaking advantage of the recent description of the fluorescence self quenched substrate di-eosin-oxidized-glutathion (DiE-GSSG), we determined kinetically the effects of various potential pharmaceutical EDCs on the in-vitro reductase activity of bovine liver PDI by measuring the fluorescence of the reaction product (E-GSH). Our data show that estrogens (ethynylestradiol and bisphenol-A) as well as indomethacin exert an inhibition whereas medroxyprogesteroneacetate and nortestosterone exert a potentiation of bovine PDI reductase activity.ConclusionsThe present data indicate that the tested EDCs could not only affect endocrine target cells through nuclear receptors as previously shown, but could also affect these and all other cells by positively or negatively affecting PDI activity. The substrate DiE-GSSG has been demonstrated to be a convenient substrate to measure PDI reductase activity in the presence of various potential EDCs. It will certainely be usefull for the screening of potential effect of all kinds of chemicals on PDI reductase activity.

Highlights

Endocrine-disrupting compounds are commonly considered as molecules acting either by mimicking or by blocking the transcriptionnal activation of hormone nuclear receptors such as those for estrogens, androgens, progestagens, thyroid hormones etc [1,2]
The present data indicate that the tested endocrinedisrupter compounds (EDC) could affect endocrine target cells through nuclear receptors as previously shown, but could affect these and all other cells by positively or negatively affecting Protein Disulfide Isomerase (PDI) activity
The substrate DiE-GSSG has been demonstrated to be a convenient substrate to measure PDI reductase activity in the presence of various potential EDCs. It will certainely be usefull for the screening of potential effect of all kinds of chemicals on PDI reductase activity

Summary

Introduction

Endocrine-disrupting compounds are commonly considered as molecules acting either by mimicking or by blocking the transcriptionnal activation of hormone nuclear receptors such as those for estrogens, androgens, progestagens, thyroid hormones etc [1,2]. It has been reported that Protein Disulfide Isomerase which catalyzes oxidative folding of proteins [7] in the endoplasmic reticulum has been found to be a high-capacity binding protein for 17b-estradiol [5]. It was found by the same authors that 17b-estradiol displayed an inhibitory effect on isomerase activity of PDI using scrambled RNA as substrate [5]. As PDI is known to bind various molecules including hormones such as estradiol and thyroxin, we considered the hypothesis that adverse effects of endocrinedisrupter compounds (EDC) could be mediated through their interaction with PDI leading to defects in membrane or secreted proteins

Results

Discussion

Conclusion