Spi-1/PU.1 but not Fli-1 inhibits erythroid-specific alternative splicing of 4.1R pre-mRNA in murine erythroleukemia cells.
The inclusion of exon 16 in mature protein 4.1R mRNA arises from a stage-specific splicing event that occurs during late erythroid development. We have shown that mouse erythroleukemia (MEL) cells reproduce this erythroid-specific splicing event upon induction of differentiation. We here found that this splicing event is regulated specifically in erythroleukemic cells that have the potential to differentiate and produce hemoglobin, regardless of the nature of the differentiation inducer. Knowing that dysregulated expression of spi-1/pu.1 and fli-1 oncogenes is involved in MEL cell differentiation arrest, we looked at their effect on exon 16 erythroid splicing. We found that exon 16 inclusion requires Spi-1/PU.1 shutdown in MEL cells, and that enforced expression of Spi-1/PU.1 inhibits exon selection, regardless of the presence or absence of a chemical inducer. By contrast, endogenous overexpression or enforced expression of Fli-1 has no effect on exon selection. We further showed that Spi-1/PU.1 acts similarly on the endogenous and on a transfected exon 16, suggesting a promoter-independent effect of Spi-1/PU.1 on splicing regulation. This study provides the first evidence that Spi-1/PU.1 displays the unique property, not shared with Fli-1, to inhibit erythroid-specific pre-mRNA splicing in erythroleukemia cell context.
Théoleyre
Orianne
O
Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Université Lyon 1, Villeurbanne, France.
Deguillien
Mireille
M
Morinière
Madeleine
M
Starck
Joëlle
J
Moreau-Gachelin
Françoise
F
Morlé
François
F
Baklouti
Faouzi
F
D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000502:physiology*; D005091:Exons; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics* / Q000473:pathology; D051379:Mice; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D012322:RNA Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D015534:Trans-Activators / Q000502:physiology*; D014407:Tumor Cells, Cultured; D000099232:Proto-Oncogene Protein Spi-1
D017931:DNA Primers; D004268:DNA-Binding Proteins; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C497426:Fli1 protein, mouse