Previous Article | Next Article ![]()
Mol. Cell. Biol., 06 1996, 2708-2718, Vol 16, No. 6
F Melet, B Motro, DJ Rossi, L Zhang and A Bernstein
The proto-oncogene Fli-1 is a member of the ets family of transcription
factor genes. Its activation by either chromosomal translocation or
proviral insertion leads to Ewing's sarcoma in humans or erythroleukemia in
mice, respectively, Fli-1 is preferentially expressed in hematopoietic and
endothelial cells. This expression pattern resembled that of c-ets-1,
another ets gene closely related and physically linked to Fli-1. We also
generated a germ line mutation in Fli-1 by homologous recombination in
embryonic stem cells. Homozygous mutant mice exhibit thymic hypocellularity
which is not related to a defect in a specific subpopulation of thymocytes
or to increased apoptosis, suggesting that Fli-1 is an important regulator
of a prethymic T-cell progenitor. This phenotype was corrected by crossing
the Fli-1 deficient mice expressing Fli-1 cDNA. Homozygous mutant mice
remained susceptible to erythroleukemia induction by Friend murine leukemia
virus, although the latency period was significantly increased.
Surprisingly, the mutant Fli-1 allele was still a target for Friend murine
leukemia virus integration, and leukemic spleens with a rearranged Fli-1
gene expressed a truncated Fli-1 protein that appears to arise from an
internal translation initiation site and alternative splicing around the
neo cassette used in the gene targeting. The fortuitous discovery of the
mutant Fli-1 protein, revealed only as the result of the clonal expansion
of leukemic cells harboring a rearranged Fli-1 gene, suggests caution in
the interpretation of gene-targeting experiments that result in either no
or only a subtle phenotypic alteration.
Copyright © 1996, American Society for Microbiology
Generation of a novel Fli-1 protein by gene targeting leads to a defect in thymus development and a delay in Friend virus-induced erythroleukemia
Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»