The Role of Fas in Radiation Induced Apoptosis in vivo.
- Author:
Sung Hee KIM
1
;
Jinsil SEONG
;
Je Kyung SEONG
Author Information
1. Department of Radiation Oncology, Yonsei University Medical College, Korea. jsseong@yumc.yonsei.ac.kr
- Publication Type:Original Article
- Keywords:
Radiation;
Apoptosis;
Fas;
lpr
- MeSH:
Animals;
Apoptosis*;
Blotting, Western;
Fas Ligand Protein;
Humans;
Male;
Mice;
Radiation Dosage;
Reference Values;
Spleen;
Whole-Body Irradiation
- From:The Journal of the Korean Society for Therapeutic Radiology and Oncology
2002;20(3):246-252
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: It has been recognized that interaction of the Fas : Fas ligand plays an important role in radiation-induced apoptosis. The purpose of this study was to investigate the role of Fas mutation in radiation-induced apoptosis in vivo. MATERIALS AND METHODS: Mice with mutations in Fas, MRL/Mpj-Fas(lpr), and its normal control, MRL/Mpj, were used in this study. Eight-week old male mice were given whole body radiation. After irradiation, the mice were killed and their spleens were collected at different time intervals. Tissue samples were stained with hematoxylin-eosin and the numbers of apoptotic cells were scored. Regulating molecules of apoptosis including p53, Bcl-2, Bax, Bcl-XL, and Bcl-XS were also analyzed by Western blotting. RESULTS: At 25 Gy irradiation, the level of apoptosis reached the peak value at 8 hr after radiation and recovered to the normal value at 24 hr after radiation in MRL/Mpj mice. In contrast, the peak apoptosis level appeared at 4 hr after radiation in MRL/Mpj-Fas(lpr) mice. At 8 hr after radiation, the levels of apoptosis in MRL/Mpj mice and MRL/Mpj-Fas(lpr) mice were 52.3+/-7.8% and 8.0+/-8.6%, respectively (p<0.05). The expression of apoptosis regulating molecules, p53, Bcl-XL and Bcl-XS, increased in MRL/Mpj mice in response to radiation; p53 with a peak level of 3-fold at 8 h, Bcl-XL with a peak level of 3.3-fold at 12 h, and Bcl-XS with a peak level of 3-fold at 12 h after 25 Gy radiation. Bcl-2 and Bax did not show significant change in MRL/Mpj mice. However in MRL/Mpj-Fas(lpr) mice, the expression levels of p53, Bcl-2, Bax, Bcl-XL and Bcl-XS showed no significant change. CONCLUSION: The level of radiation-induced apoptosis was lower in Fas mutated mice, lpr, than in control mice. This seemed to be related to the lack of radiation-induced p53 activation in the lpr mice. This result suggests that Fas plays an important role in radiation-induced apoptosis in vivo.
