Project description:Long-term hematopoietic output is dependent on the hematopoietic stem cell (HSC) homeostasis which is maintained by a complex network of molecules. Among these, microRNAs (miRNAs) play crucial roles, while the underlying molecular basis have not been fully demonstrated. Here, we found that miR-21 is enriched in murine HSCs. Then, we generated a polyinosinic:polycytidylic acid (pIpC)-inducible mouse model (miR-21flox/flox:Mx1-Cre) to obtain a specific deletion of miR-21 in hematopoietic system. It was found that mice with conditional knockout of miR-21 exhibit an obvious perturbation of normal hematopoiesis.Further researches reveal that miR-21 deficiency affect HSC homeostasis and function. We used microarrays to detail the global programme of gene expression, and identified distinct classes of up-regulated and down-regulated genes in murine HSCs after miR-21 conditional knockout.