Beschreibung:
<jats:p>Pluripotent hematopoietic stem cells and multipotent myeloid/lymphoid progenitors express miR‐221 and miR‐222. When Pax5 expression commits these progenitors to monopotent pre‐B lymphocytes the two microRNAs (miRNAs) are downregulated. Upon transplantation, stem cells and progenitors can reside in the BM, while pre‐B cells, after their commitment, no longer do so. Retrovirally transduced, doxycycline‐induced overexpression of either miR‐221 or miR‐222 in pre‐B‐I cells does not revert their monopotency to multipotency. However, upon transplantation miR‐221, but not miR‐222, transduced pre‐B‐I cells regain the capacity to reside in the BM. Upon subsequent termination of miR‐221‐expression by removal of doxycycline, the transplanted cells leave the BM again. Microarray analyses identified 25 downregulated miR‐221‐target genes, which could function to localize phases of B‐lymphocyte development in BM before and after commitment.</jats:p>