Hematopoietic stem cells (HSCs) are a rare population of cells in blood forming tissues that can self-renew and differentiate into all blood cell lineages. The long-term objective of the candidate is to understand the underlying mechanisms and regulators of HSC fate decision and survival. We propose to study a pair of activating and inhibitory receptors named paired Ig-like receptors (PIRs) that are expressed in HSC. PIR-A (activating) and PIR-B (inhibitory) form a novel MHC class I recognition system that can constitutively regulate the activation threshold in cells that express them. PIR is involved in the regulation of cytokine, integrin, and chemokine receptor signaling pathways that are crucial for HSC and progenitor functions. Thus we hypothesize that PIRs are major regulators of hematopoietic stem cell self-renewal, migration and survival. Our preliminary findings have demonstrated that: 1) PIR expression is specifically regulated among hematopoietic HSC and progenitor cell subsets;2) Perturbing PIR expression, using a lentiviral shRNA knockdown strategy, dramatically reduces HSC re-engraftment capability;3) PIR-A knockdown HSCs display selective reduction in responsiveness to the CXCR4 ligand SDF-1a in in vitro chemotaxis assays; and 4) Knocking down PIR expression in mast cell and HSCs greatly alters their responses to SCF and IL-3, cytokines important for their survival. Based on these observations, we plan first to investigate whether altering expression levels of PIRs or PIR ligands will influence HSC engraftment capacity. Then we will try to unravel the underlying mechanisms of how PIR regulate HSC functions. Lastly, we will determine the role of PIR, as the only known MHC recognition system expressed on HSC, in HSC engraftment resistance between MHC-match and allogeneic mouse strains. Elucidating the roles of PIRs in the regulation of HSC function will increase our understanding of the underlying mechanisms controlling the proliferation and fate of HSCs. This knowledge is important for both understanding hematopoietic disorders and for the therapeutic use of HSCs. This award will provide the candidate two years of mentored and three years independent research in the field of stem and mast cell biology. Research collaborations and resources will assist the candidate in the development of the skills and autonomy required to become a successful independent investigator.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Transition Award (R00)
Project #
Application #
Study Section
Special Emphasis Panel (NSS)
Program Officer
Werner, Ellen
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
City of Hope/Beckman Research Institute
United States
Zip Code
Murakami, Jodi L; Xu, Baohui; Franco, Christopher B et al. (2016) Evidence that ?7 Integrin Regulates Hematopoietic Stem Cell Homing and Engraftment Through Interaction with MAdCAM-1. Stem Cells Dev 25:18-26
Hu, Xingbin; Garcia, Mayra; Weng, Lihong et al. (2016) Identification of a common mesenchymal stromal progenitor for the adult haematopoietic niche. Nat Commun 7:13095
Lilla, Jennifer N; Chen, Ching-Cheng; Mukai, Kaori et al. (2011) Reduced mast cell and basophil numbers and function in Cpa3-Cre; Mcl-1fl/fl mice. Blood 118:6930-8
Piliponsky, Adrian M; Chen, Ching-Cheng; Grimbaldeston, Michele A et al. (2010) Mast cell-derived TNF can exacerbate mortality during severe bacterial infections in C57BL/6-KitW-sh/W-sh mice. Am J Pathol 176:926-38
Tsai, Mindy; Chen, Ching-Cheng; Mukai, Kaori et al. (2010) Thymic stromal lymphopoietin contributes to myeloid hyperplasia and increased immunoglobulins, but not epidermal hyperplasia, in RabGEF1-deficient mice. Am J Pathol 177:2411-20
Franco, Christopher B; Chen, Ching-Cheng; Drukker, Micha et al. (2010) Distinguishing mast cell and granulocyte differentiation at the single-cell level. Cell Stem Cell 6:361-8
Chan, Charles K F; Chen, Ching-Cheng; Luppen, Cynthia A et al. (2009) Endochondral ossification is required for haematopoietic stem-cell niche formation. Nature 457:490-4