Multiple functional domains of the oncoproteins Spi-1/PU.1 and TLS are involved in their opposite splicing effects in erythroleukemic cells.
The hematopoietic transcription factor Spi-1/PU.1 is an oncoprotein participating to the malignant transformation of proerythroblasts in the Friend erythroleukemia or in the erythroleukemic process developed in spi-1 transgenic mice. Overexpression of Spi-1 in proerythroblasts blocks their differentiation. We have shown that Spi-1 promotes the use of the proximal 5'-splice site during the E1A pre-mRNA splicing and interferes with the effect of TLS (Translocated in LipoSarcoma) in this splicing assay. TLS was identified from chromosomal translocations in human liposarcoma and acute myeloid leukemia. Here, we determine the function of Spi-1 domains in splicing and in the interference with TLS. In transient transfection assays in erythroid cells, we show that the DNA binding domain cooperates with the transactivation domain or the PEST region of Spi-1 to modify the function of TLS in splicing. Interestingly, the 27 C-terminal amino acids, which determine the DNA binding activity of Spi-1, are necessary for the splicing function of Spi-1 as well as for its ability to interfere with TLS. Finally, we demonstrate that in leukemic proerythroblasts overexpressing Spi-1, TLS has lost its splicing effect. Thus, we hypothesize that oncogenic pathways in proerythroblasts may involve the ability of Spi-1 to alter splicing.
Delva
Laurent
L
Inserm U528, Section de recherche, Institut Curie, Paris, France.
Gallais
Isabelle
I
Guillouf
Christel
C
Denis
Nicole
N
Orvain
Christophe
C
Moreau-Gachelin
Francoise
F
D017500:Adenovirus E1A Proteins / Q000235:genetics; D000818:Animals; D001665:Binding Sites; D002471:Cell Transformation, Neoplastic; D004247:DNA / Q000378:metabolism; D015672:Erythroid Precursor Cells / Q000378:metabolism*; D017930:Genes, Reporter; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D014411:Neoplastic Stem Cells / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000502:physiology*; D012322:RNA Precursors / Q000378:metabolism; D022821:RNA Splice Sites / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics / Q000502:physiology*; D012334:RNA, Neoplasm / Q000378:metabolism; D034702:RNA-Binding Protein FUS / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000502:physiology*; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D000099232:Proto-Oncogene Protein Spi-1
D017500:Adenovirus E1A Proteins; D004247:DNA; D011518:Proto-Oncogene Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D012334:RNA, Neoplasm; D034702:RNA-Binding Protein FUS; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1