Epigenetic modifiers are frequently mutated in hematopoietic diseases. Understanding the functional and molecular consequences of these mutations is important for determining how the mutation manifests the disease, as well as allowing us to understand the cell fate decisions that underlie normal hematopoiesis. Recent data suggests that Kdm6b, the demethylase responsible for removing the histone H3 lysine 27 trimethylation mark (H3K27me3), is dysregulated in a myriad of blood disorders and cancers. Our evidence also suggests Kdm6b influences hematopoietic stem cell (HSC) fate decisions through the regulation of bivalent gene expression, which upon ablation of the DNA methyltransferase enzyme Dnmt3a becomes unbalanced. This suggests that Kdm6b is an important epigenetic regulator of hematopoiesis; however, to date no studies have investigated the role of Kdm6b in HSC function.
We aim to elucidate the role of Kdm6b in normal hematopoiesis in order to better understand how dysregulation of this epigenetic modifier contributes to hematopoietic disease. Using genetic mouse models, we will determine the role of Kdm6b in normal hematopoiesis through classical bone marrow transplantation methods such as competitive HSC transplants and limiting dilution assays. In order to determine the downstream targets of Kdm6b in vivo, we will use microarray and ChIP-qPCR assays on HSCs and downstream progenitors. Further, in vitro analysis will be performed on a genome-wide scale by ChIP-SEQ using an endogenously tagged cell line to explore Kdm6b specificity to bivalent domains. Lastly, we will determine if controlling Kdm6b expression in the absence of Dnmt3a resolves HSC function by using genetic mouse models and competitive HSC serial transplantations. Hypothesis: Kdm6b is essential for long-term maintenance and differentiation of HSCs, and required for normal hematopoiesis.
Aim 1 : Characterize the role of Kdm6b in normal hematopoiesis and HSC self-renewal.
Aim 2 : Identify the molecular function and downstream targets of Kdm6b in hematopoietic cells.
Aim 3 : Determine if Dnmt3a-null HSCs can be rescued through reducing Kdm6b expression levels.

Public Health Relevance

Understanding how mutations in epigenetic modifiers lead to hematopoietic diseases and disorders is important for more effective targeted therapies. This proposed study aims to identify the role and molecular targets of one such epigenetic modifier, the histone demethylase KDM6B, in normal hematopoiesis in order to better understand its role in hematopoietic stem cell self-renewal and differentiation decisions. This will allow a better understanding of how epigenetic regulation being disrupted can lead to discrepancies in hematopoietic stem cell function leading to a myriad of blood disorders.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZDK1)
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Bishop, Terry Rogers
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Washington University
Internal Medicine/Medicine
Schools of Medicine
Saint Louis
United States
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Celik, Hamza; Koh, Won Kyun; Kramer, Ashley C et al. (2018) JARID2 Functions as a Tumor Suppressor in Myeloid Neoplasms by Repressing Self-Renewal in Hematopoietic Progenitor Cells. Cancer Cell 34:741-756.e8
Ostrander, Elizabeth L; Koh, Won Kyun; Mallaney, Cates et al. (2018) The GNASR201C mutation associated with clonal hematopoiesis supports transplantable hematopoietic stem cell activity. Exp Hematol 57:14-20
Kramer, A C; Kothari, A; Wilson, W C et al. (2017) Dnmt3a regulates T-cell development and suppresses T-ALL transformation. Leukemia 31:2479-2490