Overexpression of 15-lipoxygenase in the vascular endothelium is associated with increased thymic apoptosis in LDL receptor-deficient mice

A. Afek, N. Zurgil, Y. Bar-Dayan, S. Polak-Charcon, I. Goldberg, M. Deutsch, J. Kopolovich, G. Keren, D. Harats, J. George

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Background: 15-Lipoxygenase (15-LO) is a nonheme iron-containing enzyme that catalyzes the peroxidation of fatty acids. Herein, we studied the effect of 15-LO overexpression in the vascular endothelium on thymocyte apoptosis by evaluating thymuses from low-density lipoprotein receptor-deficient (LDL-RD) mice and LDL-RD/15-LO mice. Thymuses were evaluated by immunhistochemistry and by TUNEL whereas in vitro studies were carried out by employing freshly isolated thymocytes from the respective mice and evaluation of apoptosis by propidium iodide and annexin V cytometry. Methods and Results: The apoptotic index in LDL-RD/15-LO mice was significantly higher than in the LDL-RD mice. In the thymic medulla the difference was smaller, although still significant. Freshly isolated thymus cells from LDL-RD/15-LO mice exhibited a higher rate of spontaneous cell death than controls. Incubation of thymus cells in the presence of the cell-permeable caspase-3 inhibitor DEVD-CMK resulted in a decrease in the frequency of apoptotic cells in LDL-RD/15-LO thymocytes, whereas no effect was evident in control thymocytes. The antioxidant N-acetylcysteine causes the increase in apoptosis in both groups. Conclusion: LDL-RD/15-LO mice exhibit increased thymocyte apoptosis both in vivo and in vitro. These findings may suggest a role for 15-LO in the natural selection of thymocytes.

Original languageEnglish
Pages (from-to)261-266
Number of pages6
JournalPathobiology
Volume71
Issue number5
DOIs
StatePublished - 27 Oct 2004
Externally publishedYes

Keywords

  • 15-lipoxygenase
  • Apoptosis
  • Atherosclerosis
  • Oxidation
  • Thymus

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