High c-Kit expression identifies hematopoietic stem cells with impaired self-renewal and megakaryocytic bias.
Hematopoietic stem cells (HSCs) are heterogeneous with respect to their self-renewal, lineage, and reconstitution potentials. Although c-Kit is required for HSC function, gain and loss-of-function c-Kit mutants suggest that even small changes in c-Kit signaling profoundly affect HSC function. Herein, we demonstrate that even the most rigorously defined HSCs can be separated into functionally distinct subsets based on c-Kit activity. Functional and transcriptome studies show HSCs with low levels of surface c-Kit expression (c-Kit(lo)) and signaling exhibit enhanced self-renewal and long-term reconstitution potential compared with c-Kit(hi) HSCs. Furthermore, c-Kit(lo) and c-Kit(hi) HSCs are hierarchically organized, with c-Kit(hi) HSCs arising from c-Kit(lo) HSCs. In addition, whereas c-Kit(hi) HSCs give rise to long-term lymphomyeloid grafts, they exhibit an intrinsic megakaryocytic lineage bias. These functional differences between c-Kit(lo) and c-Kit(hi) HSCs persist even under conditions of stress hematopoiesis induced by 5-fluorouracil. Finally, our studies show that the transition from c-Kit(lo) to c-Kit(hi) HSC is negatively regulated by c-Cbl. Overall, these studies demonstrate that HSCs exhibiting enhanced self-renewal potential can be isolated based on c-Kit expression during both steady state and stress hematopoiesis. Moreover, they provide further evidence that the intrinsic functional heterogeneity previously described for HSCs extends to the megakaryocytic lineage.
Human Oncology and Pathogenesis Program and 2 Department of Pathology and 3 Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065.
Joseph Y
JY
Shin
Wenhuo
W
Hu
Mayumi
M
Naramura
Christopher Y
CY
Park
D000818:Animals; D019070:Cell Lineage; D049109:Cell Proliferation; D003114:Colony-Forming Units Assay; D005472:Fluorouracil / Q000494:pharmacology; D020869:Gene Expression Profiling; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology* / Q000378:metabolism*; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D034061:Thrombopoiesis / Q000235:genetics / Q000502:physiology
D019009:Proto-Oncogene Proteins c-kit; D005472:Fluorouracil