TET2 Deficiency Inhibits Mesoderm and Hematopoietic Differentiation in Human Embryonic Stem Cells

Abstract

Ten-eleven-translocation 2 (TET2) belongs to the TET protein family that catalyzes the conversion of 5-methylcytosine into 5-hydroxymethylcytosine and plays a central role in normal and malignant adult hematopoiesis. Yet the role of TET2 in human hematopoietic development remains largely unknown. Here, we show that TET2 expression is low in human embryonic stem cell (ESC) lines and increases during hematopoietic differentiation. shRNA-mediated TET2 knockdown had no effect on the pluripotency of various ESCs. However, it skewed their differentiation into neuroectoderm at the expense of endoderm and mesoderm both in vitro and in vivo. These effects were rescued by reintroducing the targeted TET2 protein. Moreover, TET2-driven differentiation was dependent on NANOG transcriptional factor. Indeed, TET2 bound to NANOG promoter and in TET2-deficient cells the methylation of the NANOG promoter correlated with a decreased in NANOG expression. The altered differentiation resulting from TET2 knockdown in ESCs led to a decrease in both the number and the cloning capacities of hematopoietic progenitors. These defects were due to an increased apoptosis and an altered gene expression profile, including abnormal expression of neuronal genes. Intriguingly, when TET2 was knockdown in hematopoietic cells, it increased hematopoietic development. In conclusion, our work suggests that TET2 is involved in different stages of human embryonic development, including induction of the mesoderm and hematopoietic differentiation.

Dynamic Switching of Active Promoter and Enhancer Domains Regulates Tet1 and Tet2 Expression during Cell State Transitions between Pluripotency and Differentiation

“…Unlike in the mouse, TET1 levels remained stable during differentiation of human ESCs (14). Our study resolves this discrepancy by demonstrating that postimplantation mouse epiblast and epiblast-derived stem cells, which share characteristics more similar to those of human ESCs (50), already lost the bulk of Tet1 expression via exon 1b and sustained Tet1 expression predominantly by using TSSs at exon 1a.…”

“…The reiterative oxidation steps constitute both passive and active pathways in DNA demethylation; at the genome scale, this process is a fundamental part of epigenetic reprogramming (12). Tet1 and Tet2 are highly expressed in mouse ESCs and primordial germ cells relative to somatic cells: both have been implicated in early embryonic differentiation (13,14), primordial germ cell specification (15,16), imprinting (17,18), and induced pluripotency (19,20).…”

Active DNA demethylation by DNA repair: Facts and uncertainties

“…Yet, there is some controversy about the importance of TET proteins in ESC function [73,74,80,[82][83][84][85][86][87].…”

Overlapping Requirements for Tet2 and Tet3 in Normal Development and Hematopoietic Stem Cell Emergence

“…Reports using antisense morpholino depletion in zebrafish and shRNA depletion in human ESCs have implicated Tet2 in the regulation of primitive hematopoiesis; but, these results are at odds with the normal primitive hematopoiesis observed in Tet2 mutant mice and zebrafish (Ge et al, 2014; Gjini et al, 2014; Ko et al, 2015; Langlois et al, 2014). The de novo generation of HSCs during the definitive wave of hematopoiesis also appears normal in Tet2 mutant mouse and zebrafish embryos; however, the potential for additional Tet enzymes to contribute to HSC emergence during embryonic development has not been experimentally addressed in mutant animals (Gjini et al, 2014; Ko et al, 2015).…”