PROJECT SUMMARY/ABSTRACT
Hematopoiesis is responsible for producing the varied cell types found in blood. In adults, this process primarily
takes place in the bone marrow and is characterized by successive rounds of differentiation beginning with the
hematopoietic stem cell through to lineage commitment. This process involves progressive narrowing of lineage
potency as progenitors eventually commit to the production of a single cell lineage. Disruption of hematopoiesis
can lead to benign and malignant pathologies. We focus on the bipotent megakaryocytic-erythroid progenitor
(MEP), which has the potential to differentiate into a lineage committed erythroid progenitor (ErP) or a lineage
committed megakaryocytic progenitor (MkP). MEP fate specification has been studied to a limited extent,
uncovering only a small number of influences that contribute to this process. One understudied aspect of human
MEP fate specification is the role of epigenetics. KDM1A (LSD1) is known to be important for erythroid
maturation, but its role in MEP fate specification is unknown. Preliminary data using primary human cells show
that inhibition of LSD1 in primary human ErP results in the ability of erythroid committed progenitors to undergo
granulocytic-monocytic and megakaryocytic commitment. In contrast, LSD1 inhibition does not affect MkP
commitment to the megakaryocytic fate. This suggests that LSD1 only antagonizes alternative lineage potential
during erythropoiesis, and not megakaryopoiesis, even though LSD1 mRNA is expressed at similar levels in
MEP, ErP, and MkP. The goal of this proposal is to establish the mechanism by which LSD1 promotes erythroid
commitment while silencing alternative myeloid and megakaryocytic lineage potential. I will achieve these goals
utilizing a mix of functional (cell culture), genetic and epigenetic approaches to determine where and how LSD1
regulates gene expression and fate specification in MEP, ErP, and MkP. Computational analyses will determine
candidate gene targets, and potential genomic sites to force epigenetic modifications using different fusion
proteins based on the catalytically inactive Cas9 endonuclease (dCas9). These results will establish the
epigenetic mechanisms that govern erythroid lineage commitment mediated by LSD1. They will also shed light
on the distinct lineage-specific epigenetic mechanisms that mediate and maintain fate specification in
hematopoiesis.