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SPECTRAL DEPENDENCE OF UV‐INDUCED IMMEDIATE AND DELAYED APOPTOSIS: THE ROLE OF MEMBRANE AND DNA DAMAGE
Author(s) -
Godar Dianne E.,
Lucas Anne D.
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb05246.x
Subject(s) - apoptosis , phototoxicity , flow cytometry , dna damage , agarose gel electrophoresis , microbiology and biotechnology , biophysics , dna , chemistry , dna fragmentation , membrane permeability , membrane , biology , programmed cell death , biochemistry , in vitro
Abstract— The phototoxicity of each waveband region of UV radiation (UVR), i.e., UVA (32CM100 nm), UVB (290–320 nm) and UVC (200–290 nm), was correlated with an apoptotic mechanism using equilethal doses (10% survival) on murine lymphoma L5178Y‐R cells. Apoptosis was qualitatively monitored for DNA “ladder” formation (multiples of 200 base pair units) using agarose gel electrophoresis, while the percentages of apoptotic and membrane‐permeabilized cells were quantified over a postexposure time course using flow cytometry. The UVA1 radiation (340–400 nm) induced both an immediate (<4 h) and a delayed (>20 h) apoptotic mechanism, while UVB or UVC radiation induced only the delayed mechanism. The role of membrane damage was examined using a lipophilic free‐radical scavenger, vitamin E. Immediate apoptosis and membrane permeability increased in a UVA1 dose‐dependent manner, both of which were reduced by vitamin E. However, vitamin E had little effect on UVR‐induced delayed apoptosis. In contrast, the DNA damaging agents 2,4‐ and 2,6‐diaminotoluene exclusively induced delayed apoptosis. Thus, immediate apoptosis can be initiated by UVA 1‐induced membrane damage, while delayed apoptosis can be initiated by DNA damage. Moreover, the results suggest that immediate and delayed apoptosis are two independent mechanisms that exist beyond the realm of photobiology.