Ultraviolet exposure of thymocytes: selective inhibition of apoptosis

Ojeda, F; Guarda, MI; Lovengreen, C; Hidalgo, MA; Folch H.; Hartel, S; Maldonado, C

Abstract

Purpose: To evaluate selective effects of ultraviolet (UV) irradiation on spontaneous and induced apoptosis in freshly extracted mice thymocytes. Materials and methods: Cells were exposed to UV radiation with emission peaks of 365 nm (UVA) exposures of 1620-10 200 J m-2, of 312 nm (UVB) exposures of 34-1620 J m-2 or of 254 nm (UVC) exposures of 1.5-1620 J m-2, and incubated for 5.5 h with or without hydrocortisone, phorbol-12-myristate-13-acetate or anti-Fas antibody. Additionally, cells were irradiated with gamma-rays (5 Gy) before UVB exposure (4-08 J m-2) at different times. Apoptosis was quantified by DNA fragmentation. Results: Up to an irradiation of 5000 J m-2, UVA exposure did not show any effect on thymocyte apoptosis, while at 10 200 J m-2 irradiation, considerable DNA fragmentation was observed. In contrast, UVB and UVC irradiation clearly inhibited natural and cortisone-induced apoptosis. Moreover, UVB inhibited apoptosis triggered by phorbol-12-myristate-13-acetate and gamma-irradiation, but not by anti-Fas antibody. Conclusions: The response of mouse thymocytes in culture to UV irradiation strongly depends on the wavelength used. It is suggested that either a survival or an apoptotic pathway occurs depending on the physiological state of the cell, spectral composition of the UV light and cell type. The possible involvement of extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun N-terminal kinase in the apoptotic pathway is discussed.

Más información

Título según WOS: Ultraviolet exposure of thymocytes: selective inhibition of apoptosis
Título según SCOPUS: Ultraviolet exposure of thymocytes: Selective inhibition of apoptosis
Título de la Revista: INTERNATIONAL JOURNAL OF RADIATION BIOLOGY
Volumen: 80
Número: 6
Editorial: Taylor and Francis Ltd.
Fecha de publicación: 2004
Página de inicio: 445
Página final: 450
Idioma: English
URL: http://informahealthcare.com/doi/abs/10.1080/09553000410001702328
DOI:

10.1080/09553000410001702328

Notas: ISI, SCOPUS