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Blood. 2011 Jul 28;118(4):903-15. doi: 10.1182/blood-2010-11-318022. Epub 2011 Jun 7.

Ddx18 is essential for cell-cycle progression in zebrafish hematopoietic cells and is mutated in human AML.

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1
Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA. e.payne@ucl.ac.uk

Abstract

In a zebrafish mutagenesis screen to identify genes essential for myelopoiesis, we identified an insertional allele hi1727, which disrupts the gene encoding RNA helicase dead-box 18 (Ddx18). Homozygous Ddx18 mutant embryos exhibit a profound loss of myeloid and erythroid cells along with cardiovascular abnormalities and reduced size. These mutants also display prominent apoptosis and a G1 cell-cycle arrest. Loss of p53, but not Bcl-xl overexpression, rescues myeloid cells to normal levels, suggesting that the hematopoietic defect is because of p53-dependent G1 cell-cycle arrest. We then sequenced primary samples from 262 patients with myeloid malignancies because genes essential for myelopoiesis are often mutated in human leukemias. We identified 4 nonsynonymous sequence variants (NSVs) of DDX18 in acute myeloid leukemia (AML) patient samples. RNA encoding wild-type DDX18 and 3 NSVs rescued the hematopoietic defect, indicating normal DDX18 activity. RNA encoding one mutation, DDX18-E76del, was unable to rescue hematopoiesis, and resulted in reduced myeloid cell numbers in ddx18(hi1727/+) embryos, indicating this NSV likely functions as a dominant-negative allele. These studies demonstrate the use of the zebrafish as a robust in vivo system for assessing the function of genes mutated in AML, which will become increasingly important as more sequence variants are identified by next-generation resequencing technologies.

PMID:
21653321
PMCID:
PMC3148170
DOI:
10.1182/blood-2010-11-318022
[Indexed for MEDLINE]
Free PMC Article
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