Two Stem Cell Biology Training Program Thesis Defenses

On Thursday, June 15, 2017 two Stem Cell Biology Training program students will give their Thesis Defenses:

Vanguel Trapkov - Stadtfeld Lab

Title: "Transgenic systems to study the transcriptional regulation of in vitro
hematopoietic progenitor cell emergence"

Time: 9:30 - 10:30am

Location: Skirball 4th Floor Seminar Room

Abstract: Blood is maintained by hematopoietic stem and progenitor cells (HSPCs), which constantly
replace mature blood cell types lost to injury or turnover and which are under the tight control of
signaling pathways and transcriptional regulators. Unraveling this interplay is instrumental for our
understanding of hematological malignancies and the generation of HSPCs in vitro.
Our work focused on studying transcriptional requirements of specifying HSPC from
pluripotent as well as non-hematopoietic cells in vitro, with the goal to understand the process of
hematopoietic commitment during mammalian hematopoietic development, but also address the
critical clinical need of the shortage of patient matched cells for bone marrow transplantation.
Specifically, we aimed to generate transgenic systems to allow a) understanding the role of the
critical transcription factor (TF) RUNX1 in driving the developmental conversion of hemogenic
endothelium (HE) into HSPCs; b) the identification of co-regulators of RUNX1 function in this
process and c) the study of two hematopoietic TF triads – RUNX1-SCL-GATA2 and FOS-GFI1BGATA2
in their ability to initiate hematopoiesis.
Our studies revealed an important dosage requirement of RUNX1 for the kinetics of HSPC
emergence and the functional properties of generated blood progenitors. In addition, we have
identified a set of HE-associated transcriptional regulators that fail to be appropriately silenced in
HPCs in vitro and whose importance for HPC quality we have evaluated. Finally, we show that
FGG can expand pre-existing macrophages in skin biopsies and that both triads support HSPC
specification during directed differentiation. Overall our studies demonstrate the importance of
precise TF regulation during the emergence of HSPCs and open new avenues for the studies of
combinatorial TF interactions during in vitro blood generation.

Evgenia Korol - Tahiliani Lab

Title: "In search of Novel TET2 Functions"

Time: 2:00 - 3:00pm

Location: Skirball 3rd Floor Seminar Room

Abstract:

Organisms use DNA as a blueprint for encoding instructions to our cells, maintaining their life cycle, and supporting the propagation of future generations. The DNA code is tightly regulated -- depending on the cell type and environmental conditions, certain regions of this genetic blueprint are more or less accessible to the cell. One form of regulation is methylation of the 5th carbon position of the cytosine base (5mC) to form 5-methylcytosine (5mC) within our genome. Cytosine methylation affects all aspects of cellular processes and plays an important role in areas ranging from X-chromosome inactivation to prevention of disease development. The study of this mechanism promises to give us the ability to better control cellular processes and prevent disease. The Ten-Eleven Translocation proteins (TET1, TET2 and TET3) are able to oxidize the methyl group on 5mC. In order to learn about the function of these TET modifications, we performed the tandem affinity purification (TAP) experiment to identify proteins that associate with TET2. By identifying proteins that interact with TET2, we sought to learn and understand the implications of TET enzymatic activity in cells. We identified P54NRB/Nono, PSPC1 and SFPQ as associated partners of TET2. Finally, we show that the interaction betweenTet2 and P54NRB/Nono could be occurring at a subset of bivalent genes in mESC, suggesting their potential role in the regulation or maintenance of the bivalency of these genes during the early development of an organism.