Erythroblast transformation by FLI-1 depends upon its specific DNA binding and transcriptional activation properties.
FLI-1 is a transcriptional regulator of the ETS family of proteins. Insertional activation at the FLI-1 locus is an early event in F-murine leukemia virus-induced erythroleukemia. Consistent with its essential role in erythroid transformation, enforced expression of FLI-1 in primary erythroblasts strongly impairs the response of these cells to erythropoietin (Epo), a cytokine essential to erythropoiesis. We show here that point mutations in the ETS domain that abolished FLI-1 binding to specific DNA elements (ETS-binding sites) suppressed the ability of FLI-1 to transform erythroblasts. The exchange of the entire ETS domain (DNA binding domain) of FLI-1 for that of PU.1 changed the DNA binding specificity of FLI-1 for that of PU.1 and impaired FLI-1 transforming properties. In contrast, ETS domain swapping mutants that maintained the DNA binding specificity of FLI-1 did not affect the ability of FLI-1 to transform erythroblasts. Deletion and swapping mutants that failed to inhibit the DNA binding activity of FLI-1 but impaired its transcriptional activation properties were also transformation-defective. Taken together, these results show that both the ability of FLI-1 to inhibit Epo-induced differentiation of erythroblasts and to confer enhanced cell survival in the absence of Epo critically depend upon FLI-1 ETS-binding site-dependent transcriptional activation properties.
CNRS UMR 146, Institut Curie, Centre Universitaire, Bâatiment 110, 91405 Orsay, France.
Sabine
S
Ano
Rui
R
Pereira
Martine
M
Pironin
Isabelle
I
Lesault
Caroline
C
Milley
Ingrid
I
Lebigot
Christine Tran
CT
Quang
Jacques
J
Ghysdael
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002645:Chickens; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004900:Erythroblasts / Q000378:metabolism / Q000473:pathology; D004921:Erythropoietin / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D051379:Mice; D011485:Protein Binding; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; C497426:Fli1 protein, mouse; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D004921:Erythropoietin; D004247:DNA