AUTHOR=Neelamraju Yaseswini , Gjini Evisa , Chhangawala Sagar , Fan Hao , He Shuning , Jing Chang-Bin , Nguyen Ashley T. , Prajapati Subhash , Sheridan Caroline , Houvras Yariv , Melnick Ari , Look A. Thomas , Garrett-Bakelman Francine E. 

TITLE=Depletion of tet2 results in age-dependent changes in DNA methylation and gene expression in a zebrafish model of myelodysplastic syndrome

JOURNAL=Frontiers in Hematology

VOLUME=2

YEAR=2023

URL=https://www.frontiersin.org/journals/hematology/articles/10.3389/frhem.2023.1235170

DOI=10.3389/frhem.2023.1235170

ISSN=2813-3935

ABSTRACT=<sec><title>Introduction</title><p>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 (<italic>tet</italic>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 <italic>tet2</italic> gene. The <italic>tet2<sup>m/m</sup></italic>-mutant zebrafish developed a pre-MDS state with kidney marrow dysplasia, but normal circulating blood counts by 11 months of age and accompanying anemia, signifying the onset of MDS, by 24 months of age.</p></sec><sec><title>Methods</title><p>In the current study, we collected progenitor cells from the kidney marrows of the adult <italic>tet2<sup>m/m</sup></italic> and <italic>tet2<sup>wt/wt</sup></italic> fish at 4 and 15 months of age and conducted enhanced reduced representation of bisulfite sequencing (ERRBS) and bulk RNA-seq to measure changes in DNA methylation and gene expression of hematopoietic stem and progenitor cells (HSPCs).</p></sec><sec><title>Results and discussion</title><p>A global increase in DNA methylation of gene promoter regions and CpG islands was observed in <italic>tet2<sup>m/m</sup></italic> HSPCs at 4 months of age when compared with the wild type. Furthermore, hypermethylated genes were significantly enriched for targets of SUZ12 and the metal-response-element-binding transcription factor 2 (MTF2)—involved in the polycomb repressive complex 2 (PRC2). However, between 4 and 15 months of age, we observed a paradoxical global decrease in DNA methylation in <italic>tet2<sup>m/m</sup></italic> HSPCs. Gene expression analyses identified upregulation of genes associated with mTORC1 signaling and interferon gamma and alpha responses in <italic>tet2<sup>m/m</sup></italic> HSPCs at 4 months of age when compared with the wild type. Downregulated genes in HSPCs of <italic>tet2</italic>-mutant fish at 4 months of age were enriched for cell cycle regulation, heme metabolism, and interleukin 2 (IL2)/signal transducer and activator of transcription 5 (STAT5) signaling, possibly related to increased self-renewal and clonal advantage in HSPCs with <italic>tet2</italic> loss of function. Finally, there was an overall inverse correlation between overall increased promoter methylation and gene expression.</p></sec>