Downregulation of the Spi-1/PU.1 oncogene induces the expression of TRIM10/HERF1, a key factor required for terminal erythroid cell differentiation and survival.
Sustained expression of the Spi-1/PU.1 and Fli-1 oncoproteins blocks globin gene activation in mouse erythroleukemia cells; however, only Spi-1/PU.1 expression inhibits the inclusion of exon 16 in the mature 4.1R mRNA. This splicing event is crucial for a functional 4.1R protein and, therefore, for red blood cell membrane integrity. This report demonstrates that Spi-1/PU.1 downregulation induces the activation of TRIM10/hematopoietic RING finger 1 (HERF1), a member of the tripartite motif (TRIM)/RBCC protein family needed for globin gene transcription. Additionally, we demonstrate that TRIM10/HERF1 is required for the regulated splicing of exon 16 during late erythroid differentiation. Using inducible overexpression and silencing approaches, we found that: (1) TRIM10/HERF1 knockdown inhibits hemoglobin production and exon splicing and triggers cell apoptosis in dimethylsulfoxide (DMSO)-induced cells; (2) TRIM10/HERF1 upregulation is required but is insufficient on its own to activate exon retention; (3) Fli-1 has no effect on TRIM10/HERF1 expression, whereas either DMSO-induced downregulation or shRNA-knockdown of Spi-1/PU.1 expression is sufficient to activate TRIM10/HERF1 expression; and (4) Spi-1/PU.1 knockdown triggers both the transcription and the splicing events independently of the chemical induction. Altogether, these data indicate that primary Spi-1/PU.1 downregulation acts on late erythroid differentiation through at least two pathways, one of which requires TRIM10/HERF1 upregulation and parallels the Spi-1/PU.1-induced Fli-1 shutoff regulatory cascade.
Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Université Lyon 1, Bât. Gregor Mendel, 16, rue R. Dubois, 69622 Villeurbanne, France.
Rand
R
Blaybel
Orianne
O
Théoleyre
Alexandre
A
Douablin
Faouzi
F
Baklouti
D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D015536:Down-Regulation / Q000235:genetics; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology*; D006454:Hemoglobins / Q000096:biosynthesis; D006649:Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008840:Microfilament Proteins; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012326:RNA Splicing / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D000070584:Tripartite Motif Proteins; D015854:Up-Regulation / Q000235:genetics; D000099232:Proto-Oncogene Protein Spi-1
D001798:Blood Proteins; D002352:Carrier Proteins; D004121:Dimethyl Sulfoxide; D006454:Hemoglobins; D006649:Histocompatibility Antigens; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D000070584:Tripartite Motif Proteins; D000099232:Proto-Oncogene Protein Spi-1; C514956:Epb41 protein, mouse; C497426:Fli1 protein, mouse; C108239:TRIM10 protein, human; C532481:TRIM10 protein, mouse