Volume 2013 (2013), Article ID 637897, 7 pages
Transsulfuration Is a Significant Source of Sulfur for Glutathione Production in Human Mammary Epithelial Cells
1Department of Chemistry, Marshall University, One John Marshall Drive, Huntington, WV 25755-0003, USA
2Department of Pharmacology, Physiology & Toxicology, Marshall University Joan C. Edwards School of Medicine, One John Marshall Drive, Huntington, WV 25755-0003, USA
3Department of Anatomy and Pathology, Marshall University Joan C. Edwards School of Medicine, One John Marshall Drive, Huntington, WV 25755-0003, USA
Received 22 January 2013; Accepted 16 February 2013
Academic Editors: A.-M. Lambeir and B. Lenarcic
Copyright © 2013 Andrea D. Belalcázar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The transsulfuration pathway, through which homocysteine from the methionine cycle provides sulfur for cystathionine formation, which may subsequently be used for glutathione synthesis, has not heretofore been identified as active in mammary cells. Primary human mammary epithelial cells (HMEC’s) were labeled with -methionine for 24 hours following pretreatment with a vehicle control, the cysteine biosynthesis inhibitor propargylglycine or the gamma-glutamylcysteine synthesis inhibitor buthionine sulfoximine. Cell lysates were prepared and reacted with glutathione-S-transferase and the fluorescent labeling compound monochlorobimane to form a fluorescent glutathione-bimane conjugate. Comparison of fluorographic and autoradiographic images indicated that glutathione had incorporated -methionine demonstrating that functional transsulfuration occurs in mammary cells. Pathway inhibitors reduced incorporation by roughly 80%. Measurement of glutathione production in HMEC’s treated with and without hydrogen peroxide and/or pathway inhibitors indicates that the transsulfuration pathway plays a significant role in providing cysteine for glutathione production both normally and under conditions of oxidant stress.