B lymphocytes are critical blood cells and altered production or function can cause significant disease. We are interested in understanding how blood stem cells initiate B cell development. Delineating the normal B cell developmental pathway will provide insight into the molecular and cellular basis of many hematologic diseases. Although considerable progress has been made in understanding the generation of naive B cells from committed B cell precursors, little is known about how this process begins. This project will exploit exciting new findings concerning an unexpected regulatory connection between the receptor tyrosine kinase Flt3, HoxA proteins, and the B cell fate determinant EBF. Our new data suggest that this regulatory connection plays an important role in regulating the stem cell to Pro-B transition, and hence, the numbers of B lymphocytes generated. Specifically, we will learn how Flt3 signaling initiates a series of events, gradually biasing multipotential progenitors in bone marrow into the B lineage. Exciting new data revealed that Flt3 signaling, in a ligand-dose dependent fashion, regulates the activity of the primary B cell fate determinant, E2A, a key regulator of the EBF gene. Once expressed, EBF orchestrates B cell differentiation. Gene expression profiling of an EBF-/- cell line pointed to novel role for EBF during B cell development, namely controlling expression of a developmentally regulated cluster of HoxA proteins. Elucidating regulatory circuits that control HoxA expression is important, as dysregulated expression impairs B cell differentiation. First we will determine the molecular events between Flt3 signaling and EBF expression. Then we will determine the regulatory connection between EBF, HoxA, and Flt3 that controls the production of B lymphocytes. Overall, these experiments will provide basic knowledge of a vital process, the production of white blood cells that make antibodies to fight infections. The information should help identify molecular targets for intervention in blood cell cancers and immunodeficiency diseases.

Public Health Relevance

During blood cell development, the stem cell to Pro-B transition is a pivotal checkpoint that controls B cell homeostasis. This project focuses on determining the molecular circuitry through which three critical factors, the receptor tyrosine kinase Flt3, HoxA proteins, and the B cell fate determinant EBF, orchestrate this critical checkpoint.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL096108-04
Application #
8232043
Study Section
Hematopoiesis Study Section (HP)
Program Officer
Thomas, John
Project Start
2009-04-06
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
4
Fiscal Year
2012
Total Cost
$377,750
Indirect Cost
$127,750
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Dolence, Joseph J; Gwin, Kimberly A; Shapiro, Mariya B et al. (2014) Flt3 signaling regulates the proliferation, survival, and maintenance of multipotent hematopoietic progenitors that generate B cell precursors. Exp Hematol 42:380-393.e3
Iida, Ryuji; Welner, Robert S; Zhao, Wanke et al. (2014) Stem and progenitor cell subsets are affected by JAK2 signaling and can be monitored by flow cytometry. PLoS One 9:e93643
Gwin, Kimberly; Dolence, Joseph J; Shapiro, Mariya B et al. (2013) Differential requirement for Hoxa9 in the development and differentiation of B, NK, and DC-lineage cells from Flt3+ multipotential progenitors. BMC Immunol 14:5
Gwin, Kimberly A; Shapiro, Mariya B; Dolence, Joseph J et al. (2013) Hoxa9 and Flt3 signaling synergistically regulate an early checkpoint in lymphopoiesis. J Immunol 191:745-54
Zhang, Qingzhao; Esplin, Brandt L; Iida, Ryuji et al. (2013) RAG-1 and Ly6D independently reflect progression in the B lymphoid lineage. PLoS One 8:e72397
Shimazu, Tomoyuki; Iida, Ryuji; Zhang, Qingzhao et al. (2012) CD86 is expressed on murine hematopoietic stem cells and denotes lymphopoietic potential. Blood 119:4889-97
Dolence, Joseph J; Gwin, Kimberly; Frank, Elena et al. (2011) Threshold levels of Flt3-ligand are required for the generation and survival of lymphoid progenitors and B-cell precursors. Eur J Immunol 41:324-34
Gwin, Kimberly; Frank, Elena; Bossou, Ayoko et al. (2010) Hoxa9 regulates Flt3 in lymphohematopoietic progenitors. J Immunol 185:6572-83