Transfection of p53-knockout mouse fibroblasts with wild-type p53 increases the thermosensitivity and stimulates apoptosis induced by heat stress.
OBJECTIVE
The relationship between the p53 functions and cellular thermosensitivity was evaluated using murine fibroblasts transfected with either wild-type p53 or mutated p53, or those with a null p53 genotype.


METHODS
Cellular thermosensitivity was determined using the clonogenic assay. Cell cycle distribution was assayed by determining DNA content using flow cytometer. Apoptosis was analyzed by detection of both apoptotic bodies and DNA fragmentation.


RESULTS
Stable transfectant with either wild-type p53 or mutated p53 was established. The transfectants with wild-type p53 were more thermosensitive than either those with a null p53 or with mutated p53. Although heat-induced G1 cell cycle arrest was substantially observed in all transfectants, wild-type p53 enhanced and prolonged the G1 arrest. Furthermore, wild-type p53 stimulated the induction of apoptosis by heat stress, whereas mutated p53 delayed it extremely.


CONCLUSIONS
The p53 gene is at least a factor for determining cellular thermosensitivity and wild-type p53 contributes to thermosensitization resulting in enhancement of heat-induced apoptosis.
Matsumoto
H
H
Department of Biology, Nara Medical University, Kashihara, Japan.
Takahashi
A
A
Wang
X
X
Ohnishi
K
K
Ohnishi
T
T
D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002467:Cell Nucleus; D002470:Cell Survival; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D016193:G1 Phase / Q000235:genetics; D016158:Genes, p53 / Q000235:genetics*; D005838:Genotype; D006358:Hot Temperature; D006979:Hyperthermia, Induced; D051379:Mice; D018345:Mice, Knockout; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53