Knock-in mice with a chimeric human/murine p53 gene develop normally and show wild-type p53 responses to DNA damaging agents: a new biomedical research tool
Jl. Luo et al., Knock-in mice with a chimeric human/murine p53 gene develop normally and show wild-type p53 responses to DNA damaging agents: a new biomedical research tool, ONCOGENE, 20(3), 2001, pp. 320-328
The high prevalence and great diversity of p53 tumor suppressor gene mutati
ons in human tumors call for development of therapeutic molecules that resc
ue function of aberrant p53 protein. P53 mutations also offer new approache
s to the study of the origins of mutations in human cancer. An experimental
mouse model with a genetically modified but normal functioning p53 gene ha
rboring the human rather than the murine core domain, would be of considera
ble benefit to research on both cancer therapeutics and etiology; however,
it is uncertain whether such mice would permit biological functions of p53
to be retained. Using a Cre/lox P gene-targeting approach, we have construc
ted a human p53 knock-in (hupki) mouse strain in which exons 4-9 of the end
ogenous mouse p53 allele were replaced with the homologous, normal human p5
3 gene sequence, The chimeric p53 allele (p53(KI)) is properly spliced, tra
nscribed in various tissues at levels equivalent to wild-type mice, and yie
lds cDNA with the anticipated sequence, that is, with a core domain matchin
g that of humans. The hupki p53 protein binds to p53 consensus sequences in
gel mobility shift assays and accumulates in the nucleus of hupki fibrobla
sts in response to UV irradiation, as is characteristic of wild-type p53, I
nduction of various p53-regulated genes in spleen of gamma -irradiated homo
zygous hupki mice (p53(KI/KI)), and the kinetics of p53-dependent apoptosis
in thymocytes are similar to results with wild-type (p53(+/+)) mice, furth
er indicating normal p53 pathway function in the hupki strain, The mice are
phenotypically normal and do not develop spontaneous tumors at an early ag
e, in contrast to knock-out (p53(-/-)) strains with a defective p53 gene. T
he chimeric (p53(KI)) allele thus appears to provide a biological equivalen
t to the endogenous murine (p53(+)) gene. This strain is a unique tool for
examining in vivo spontaneous and induced mutations in human p53 gene seque
nces for comparison with published human tumor p53 mutation spectra, In add
ition, the hupki strain paves the way for mouse models in pre-clinical test
ing of pharmaceuticals designed to modulate DNA-binding activity of human p
53.