Lineage fate decisions of hematopoietic stem cells

Description of projects available to graduate students:
We have shown that the transcription factor E47 regulates the expression of lineage-specific genes required for the specification of stem cells to the B lymphocyte lineage. The mechanisms by which E47 activity is regulated in primary hematopoietic progenitors remain to be determined. Studies in a pro B cell line demonstrate that E47 activity is antagonized by Notch signals. This is an intriguing observation because Notch plays a major role in directing B versus T lymphocyte fate decisions in uncommitted progenitors with Notch activation blocking B lymphopoiesis and favoring T lymphopoiesis. However, it is unknown if E47 is a major Notch target during B lineage fate specification, or if Notch even regulates E47 in primary hematopoietic precursors. The first goal of this proposal is to determine the effect of Notch on E47 expression and trans-activation potential during B lineage fate specification. We then focus on the B1 B cell subset, a B cell lineage with distinct developmental requirements and function relative to canonical B2 B cells. We propose to determine if E47 controls normal development of, and VDJ recombination in, B1 lineage progenitors. Our central hypothesis is that E47 activity in B cell progenitors is regulated by Notch, and that E47 is fundamentally required for VDJ recombination initiation in both the B2 and B1 B lymphocyte lineages. By contrast, E47 is dispensable for VDJ recombinase activity in T cell progenitors, and we propose to determine the factors that initiate recombination in this lineage. Establishing the lineage-specific activities of E47 and the mechanisms of E47 regulation is important for understanding the molecular processes that underlie cell fate decisions, and how perturbations in E47 activity cause cancers of B and T lymphoid origin.

Techniques graduate student will learn:
flow cytometry
single cell PCR, real time PCR
identification of lymphocyte subsets in mouse and man
cell culture
retroviral technology