The BioTECH Quarterly
Student Research Spotlight
By Delbert A. Green II ’08
Aberrant expression of different transcription factors in hematopoietic (blood) cells has been implicated in several hematological disorders. In acute myeloid leukemia (AML), anomalous cells accumulate in the bone marrow, replace normal blood cells, and spread to other organs. Myelodysplastic syndrome (MDS) is characterized by the accumulation of genetic abnormalities in the hematopoietic stem cell (HSC).
Anomalous activation of the transcription factor Evi1 leads to AML and MDS in mice and humans. In the hematopoietic lineage, Evi1 has been shown to be expressed exclusively in the pluripotent hematopoietic stem cell (HSC), indicating that Evi1 may play a role in sustaining the pluripotency of HSCs.
In order to determine the role of Evi1 in adult hematopoiesis, thus defining the role of Evi1 in AML and MDS, we have created both in vitro and in vivo models of retroviral infection-induced over expression and ablation of Evi1 in HSCs.
EMLs, a hematopoietic progenitor cell line, were infected with a retrovirus harboring an siRNA for silencing of Evi1. One to two days post-infection, Evi1-deficient HSCs show a slowed growth rate and morphology uncharacteristic of the HSC. After several days, most Evi1-deficient HSCs have died, though few show the morphology of red blood cells.
Bone marrow-derived HSCs infected with the Evi1-siRNA were competitively transplanted into recipient mice. Evi1-deficient HSCs are unable to contribute to the blood lineage, indicating a competitive advantage of Evi1-positive HSCs in forming the hematopoietic system (Fig. 1).
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