Depletion of results in age-dependent changes in DNA methylation and gene expression in a zebrafish model of myelodysplastic syndrome.

Introduction: Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic disorders characterized by ineffective hematopoiesis, cytopenias, and dysplasia. The gene encoding ten-eleven translocation 2 (2), a dioxygenase enzyme that catalyzes the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine, is a recurrently mutated tumor suppressor gene in MDS and other myeloid malignancies. Previously, we reported a stable zebrafish line with a loss-of-function mutation in the gene.

Synthetic lethal targeting of TET2-mutant haematopoietic stem and progenitor cells by XPO1 inhibitors.

TET2 inactivating mutations serve as initiating genetic lesions in the transformation of haematopoietic stem and progenitor cells (HSPCs). In this study, we analysed known drugs in zebrafish embryos for their ability to selectively kill tet2-mutant HSPCs in vivo. We found that the exportin 1 (XPO1) inhibitors, selinexor and eltanexor, selectively kill tet2-mutant HSPCs.

Synergistic melanoma cell death mediated by inhibition of both MCL1 and BCL2 in high-risk tumors driven by NF1/PTEN loss.

Melanomas driven by loss of the NF1 tumor suppressor have a high risk of treatment failure and effective therapies have not been developed. Here we show that loss-of-function mutations of nf1 and pten result in aggressive melanomas in zebrafish, representing the first animal model of NF1-mutant melanomas harboring PTEN loss. MEK or PI3K inhibitors show little activity when given alone due to cross-talk between the pathways, and high toxicity when given together.

Synthetic lethal targeting of TET2-mutant hematopoietic stem and progenitor cells (HSPCs) with TOP1-targeted drugs and PARP1 inhibitors.

Inactivating mutations in TET2 serve as an initiating genetic lesion in the transformation of hematopoietic stem and progenitor cells (HSPCs). Thus, effective therapy for this subset of patients would ideally include drugs that are selectively lethal in TET2-mutant HSPCs, at dosages that spare normal HSPCs. In this study, we tested 129 FDA-approved anticancer drugs in a tet2-deficient zebrafish model and showed that topoisomerase 1 (TOP1)-targeted drugs and PARP1 inhibitors selectively kill tet2-mutant HSPCs.

Disruption of results in myeloproliferative neoplasms in zebrafish.

Somatic loss-of-function mutations of the additional sex combs-like transcriptional regulator 1 () gene are common genetic abnormalities in human myeloid malignancies and induce clonal expansion of mutated hematopoietic stem cells (HSCs). To understand how disruption leads to myeloid cell transformation, we generated haploinsufficient and null zebrafish lines using genome-editing technology. Here, we show that homozygous loss of leads to apoptosis of newly formed HSCs.

Phospholipase C gamma-1 is required for granulocyte maturation in zebrafish.

The regulation of hematopoiesis is generally evolutionarily conserved from zebrafish to mammals, including hematopoietic stem cell formation and blood cell lineage differentiation. In zebrafish, primitive granulocytes originate at two distinct regions, the anterior lateral plate mesoderm (A-LPM) and the intermediate cell mass (ICM). Few studies in the zebrafish have examined genes specifically required for the granulocytic lineage.

Heritable and lineage-specific gene knockdown in zebrafish embryo.

Background: Reduced expression of developmentally important genes and tumor suppressors due to haploinsufficiency or epigenetic suppression has been shown to contribute to the pathogenesis of various malignancies. However, methodology that allows spatio-temporally knockdown of gene expression in various model organisms such as zebrafish has not been well established, which largely limits the potential of zebrafish as a vertebrate model of human malignant disorders.

Principal Finding: Here, we report that multiple copies of small hairpin RNA (shRNA) are expressed from a single transcript that mimics the natural microRNA-30e precursor (mir-shRNA).

Mir-144 selectively regulates embryonic alpha-hemoglobin synthesis during primitive erythropoiesis.

Precise transcriptional control of developmental stage-specific expression and switching of alpha- and beta-globin genes is significantly important to understand the general principles controlling gene expression and the pathogenesis of thalassemia. Although transcription factors regulating beta-globin genes have been identified, little is known about the microRNAs and trans-acting mechanism controlling alpha-globin genes transcription. Here, we show that an erythroid lineage-specific microRNA gene, miR-144, expressed at specific developmental stages during zebrafish embryogenesis, negatively regulates the embryonic alpha-globin, but not embryonic beta-globin, gene expression, through physiologically targeting klfd, an erythroid-specific Krüppel-like transcription factor.