Critical role of FLT3 ligand in IL-7 receptor–independent T lymphopoiesis and regulation of lymphoid-primed multipotent progenitors
Open Access
- 15 October 2007
- journal article
- Published by American Society of Hematology in Blood
- Vol. 110 (8), 2955-2964
- https://doi.org/10.1182/blood-2006-10-054726
Abstract
The molecular pathways regulating lymphoid priming, fate, and development of multipotent bone marrow (BM) stem/progenitor cells that continuously replace thymic progenitors remain largely unknown. Herein, we show that fms-like tyrosine kinase 3 (Flt3) ligand (Fl)–deficient mice have distinct reductions in the earliest thymic progenitors in fetal, postnatal, and adult thymus. A critical role of FL in thymopoiesis was particularly evident in the absence of interleukin-7 receptor α (IL-7Rα) signaling. Fl−/−Il-7r−/− mice have extensive reductions in fetal and postnatal thymic progenitors that result in a loss of active thymopoiesis in adult mice, demonstrating an indispensable role of FL in IL-7Rα–independent fetal and adult T lymphopoiesis. Moreover, we establish a unique and critical role of FL, distinct from that of IL-7Rα, in regulation of the earliest lineage-negative (Lin−) Lin−SCA1+KIT+ (LSK) FLT3hi lymphoid-primed multipotent progenitors in BM, demonstrating a key role of FLT3 signaling in regulating the very earliest stages of lymphoid progenitors.Keywords
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