RESUMEN
Lymphoid-primed multipotent progenitors with down-regulated megakaryocyte-erythroid (MkE) potential are restricted to cells with high levels of cell-surface FLT3 expression, whereas HSCs and MkE progenitors lack detectable cell-surface FLT3. These findings are compatible with FLT3 cell-surface expression not being detectable in the fully multipotent stem/progenitor cell compartment in mice. If so, this process could be distinct from human hematopoiesis, in which FLT3 already is expressed in multipotent stem/progenitor cells. The expression pattern of Flt3 (mRNA) and FLT3 (protein) in multipotent progenitors is of considerable relevance for mouse models in which prognostically important Flt3 mutations are expressed under control of the endogenous mouse Flt3 promoter. Herein, we demonstrate that mouse Flt3 expression initiates in fully multipotent progenitors because in addition to lymphoid and granulocyte-monocyte progenitors, FLT3(-) Mk- and E-restricted downstream progenitors are also highly labeled when Flt3-Cre fate mapping is applied.
Asunto(s)
Perfilación de la Expresión Génica , Células Madre Hematopoyéticas/metabolismo , Células Madre Multipotentes/metabolismo , Tirosina Quinasa 3 Similar a fms/genética , Animales , Células de la Médula Ósea/citología , Células de la Médula Ósea/metabolismo , Trasplante de Médula Ósea , Linaje de la Célula/genética , Membrana Celular/metabolismo , Células Precursoras Eritroides/citología , Células Precursoras Eritroides/metabolismo , Citometría de Flujo , Células Precursoras de Granulocitos/citología , Células Precursoras de Granulocitos/metabolismo , Células Madre Hematopoyéticas/citología , Humanos , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Células Progenitoras de Megacariocitos/citología , Células Progenitoras de Megacariocitos/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Monocitos/citología , Monocitos/metabolismo , Células Madre Multipotentes/citología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tirosina Quinasa 3 Similar a fms/metabolismoRESUMEN
GATA3 has been identified as a master regulator of T helper cells, as well as being important for early thymic progenitors and T-cell commitment. However, Gata3 expression initiates already at the hematopoietic stem cell (HSC) level, implicating a potential role also in the regulation of HSCs. Herein we used a conditional Gata3 knockout strategy in which Gata3 expression was completely deleted from the earliest stage of embryonic hematopoietic development after emergence of HSCs from hemogenic endothelium. Through a detailed analysis of HSCs at the phenotypic and functional level, we demonstrate that steady-state levels of HSCs are normal in Gata3(fl/fl)Vav-Cre(tg/+) mice. Moreover, through long-term primary and secondary transplantation experiments, we also unequivocally demonstrate that Gata3 has a redundant role in post-transplantation HSC self-renewal.