Transcriptional repression of the Neurofibromatosis-1 tumor suppressor by the t(8;21) fusion protein.
Von Recklinghausen's disease is a relatively common familial genetic disorder characterized by inactivating mutations of the Neurofibromatosis-1 (NF1) gene that predisposes these patients to malignancies, including an increased risk for juvenile myelomonocytic leukemia. However, NF1 mutations are not common in acute myeloid leukemia (AML). Given that the RUNX1 transcription factor is the most common target for chromosomal translocations in acute leukemia, we asked if NF1 might be regulated by RUNX1. In reporter assays, RUNX1 activated the NF1 promoter and cooperated with C/EBPalpha and ETS2 to activate the NF1 promoter over 80-fold. Moreover, the t(8;21) fusion protein RUNX1-MTG8 (R/M), which represses RUNX1-regulated genes, actively repressed the NF1 promoter. R/M associated with the NF1 promoter in vivo and repressed endogenous NF1 gene expression. In addition, similar to loss of NF1, R/M expression enhanced the sensitivity of primary myeloid progenitor cells to granulocyte-macrophage colony-stimulating factor. Our results indicate that the NF1 tumor suppressor gene is a direct transcriptional target of RUNX1 and the t(8;21) fusion protein, suggesting that suppression of NF1 expression contributes to the molecular pathogenesis of AML.
Yang
Genyan
G
Department of Biochemistry, Vanderbilt University School of Medicine, PRB 512, 23rd and Pierce, Nashville, Tennessee 37232, USA.
Khalaf
Waleed
W
van de Locht
Louis
L
Jansen
Joop H
JH
Gao
Meihua
M
Thompson
Mary Ann
MA
van der Reijden
Bert A
BA
Gutmann
David H
DH
Delwel
Ruud
R
Clapp
D Wade
DW
Hiebert
Scott W
SW
D000818:Animals; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D017930:Genes, Reporter; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D051379:Mice; D009456:Neurofibromatosis 1 / Q000235:genetics*; D025542:Neurofibromin 1 / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D000075142:RUNX1 Translocation Partner 1 Protein; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014178:Translocation, Genetic / Q000235:genetics
C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D025542:Neurofibromin 1; D015514:Oncogene Proteins, Fusion; D011518:Proto-Oncogene Proteins; D000075142:RUNX1 Translocation Partner 1 Protein; C493728:RUNX1 protein, human; C082222:RUNX1T1 protein, human; D012097:Repressor Proteins; C493726:Runx1 protein, mouse; D014157:Transcription Factors; D016178:Granulocyte-Macrophage Colony-Stimulating Factor