Date of Award

January 2018

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Stephanie Halene

Abstract

N6-methyladenosine (m6A) is the most abundant modified nucleotide occurring in mRNA, with key roles in RNA metabolism and regulation of gene expression. Proposed effects of m6A modification of RNA transcripts include effects on transcript half-life, translation efficiency, splicing and miRNA biogenesis. Importantly, m6A is the only known dynamic RNA modification, with deposition mediated by the “writer” METTL3, and demethylation carried out by the “erasers” ALKBH5 and FTO. We hypothesized a role for m6A in hematopoiesis, with potential disease relevance in myeloid malignancies.

To gain an understanding of the effects of m6A on normal hematopoiesis and myeloid malignancies such as the myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), we developed conditional knockout mice for the m6A writer METTL3, and the eraser ALKBH5. We find that deletion of METTL3 results in embryonic lethality, with an accumulation of dysfunctional hematopoietic stem cells (HSCs) that are incompetent in hematopoietic rescue assays. We further characterize disturbances in myeloid & lymphoid lineage differentiation. Deletion of ALKBH5 does not result in steady-state hematopoietic dysfunction, but results in hematopoietic stem cell deficiencies in competitive transplant assays.

We propose that deletion of METTL3 locks HSCs in a naïve multipotent state, and hypothesize that ALKBH5 exerts effects on HSC function that are yet to be characterized.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 05/29/2021

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