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The role of gene regulation during white-blood cell development and the biology of hematopoietic progenitor cells.
We are attempting to elucidate factors required for lineage commitment during hematopoietic (blood cell) development. Of particular interest are transcription factors thought to influence lymphoid and myeloid differentiation. The proto-oncogene PU.1 is a member of the Ets-family of transcription factors and has been suggested to be a regulator of hematopoiesis based on its restricted expression pattern (primarily in mature B-cells and monocytes). To determine the role of PU.1 in the mouse, the gene was targeted via homologous recombination in embryonic stem cells and “knock-out” mice were generated. PU.1 mutant animals were lacking both lymphoid and myeloid development. Flow cytometric, histologic, and RT-PCR analyses demonstrated a complete lack of myeloid or lymphoid precursors. In vitro clonogenic and ES cell differentiation assays have demonstrated that the defect in myeloid and lymphoid development is cell intrinsic and not due to a defect in the hematopoietic microenvironment. Therefore, PU.1 is essential for the generation of lymphoid and myeloid progenitors. In addition, this study provides the first genetic evidence consistent with the existence of a multipotent lymphoid/myeloid progenitor in the hematopoietic system.
The laboratory will continue to investigate the developmental linkage of these lineages and the possible existence of a common multipotent progenitor during hematopoiesis. Our basic approach to this question will be a genetic approach using murine models. We use gene targeting to generate knockout ES cell lines and animals. Students can learn (or at least see) the basics of microinjection of embryos and the production of chimeric mice. We are also adapting the PU.1-/- knockout into a model for in utero gene therapy, and determining the efficacy of PU.1 antisense oligos and ribozymes in blocking myeloid differentiation / function. (Potential therapeutic agent in arteriosclerosis). We are also investigating the role of PU.1 in the hematopoietic stem cell with a series of bone marrow transplantation experiments.
Ph.D., Molecular Genetics, University of Florida
B.A., Biology, University of Chicago