Gjini, E., Mansour, M.R., Sander, J.D., Moritz, N., Nguyen, A.T., Kesarsing, M., Gans, E., He, S., Chen, S., Ko, M., Kuang, Y.Y., Yang, S., Zhou, Y., Rodig, S., Zon, L.I., Joung, J.K., Rao, A., Look, A.T. (2015) A Zebrafish Model of Myelodysplastic Syndrome Produced Through tet2 Genomic Editing. Molecular and cellular biology. 35(5):789-804.
The Ten-ElevenTranslocation-2 (TET2) gene encodes a member of the TET family of DNA methylcytosine oxidases that converts 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) to initiate the demethylation of DNA within genomic CpG islands. Somatic loss-of-function mutations of TET2 are frequently observed in human myelodysplastic syndrome (MDS), which is a clonal malignancy characterized by dysplastic changes of developing blood cell progenitors leading to ineffective hematopoiesis. We used genome editing technology to disrupt the zebrafish Tet2 catalytic domain. tet2 m/m zebrafish exhibited normal embryonic and larval hematopoiesis, but developed progressive clonal myelodysplasia as they aged, culminating in MDS at 24 months of age, with dysplasia of myeloid progenitor cells and anemia with abnormal circulating erythrocytes. The resultant tet2 m/m mutant zebrafish lines show decreased levels of 5hmC in hematopoietic cells of the kidney marrow, but not in other cell types, most likely reflecting the ability of other Tet family members to provide this enzymatic activity in non-hematopoietic tissues but not in hematopoietic cells. tet2 m/m are viable and fertile, providing an ideal model to dissect altered pathways in hematopoietic cells and for small molecule screens in embryos to identify compounds with specific activity against tet2 mutant cells.