Distinct roles of cellular copper and erythropoietin receptor on hematopoietic engraftment

Cell differentiation is influenced by a combination of cues from both extracellular and intracellular sources. Recent advances in the regulation of hematopoiesis have focused on the roles of the growth factors, cytokines, transcription factors and microRNAs; little attention has been given to the role of cellular metabolism. In the first part of this dissertation, I explored the idea that an essential cellular nutrient, copper (Cu), is an active component of cell fate regulators that influence hematopoietic progenitor cell differentiation. I showed that reducing cellular Cu content by exposing the cells to the Cu chelator tetraethylenepentamine (TEPA) enhanced the generation or maintenance of erythroid progenitor cells from multipotent progenitor cells in culture. I also provided evidence suggesting that this effect is likely due to the modulation of cellular energy metabolism by cell Cu level. In the second part of this dissertation, I investigated the effects of modulating erythropoietin receptor (EPOR) signaling intensity on mouse trilineage hematopoietic engraftment and proliferation of hematopoietic stem/progenitor cells (HSC/HPCs). I showed that neither increasing nor reducing EpoR signaling intensity influence long-term leukocyte engraftment, an indication of HSC function. I confirmed the essential role of EpoR on erythropoiesis. I also provide evidence suggesting a potential role for EpoR in megakaryopoiesis. I also demonstrated that multipotent progenitor cells with naturally-expressed hyperactive EpoR can proliferate and differentiate in response to Epo stimulation alone.