miRNomes of haematopoietic stem cells and dendritic cells identify miR-30b as a regulator of Notch1

Su, Xiaoping; Qian, Cheng; Zhang, Qian; Hou, Jin; Gu, Yan; Han, Yanmei; Chen, Yongjian; Jiang, Minghong; Cao, Xuetao

D endritic cells (DCs), the most potent professional antigenpresenting cells, are crucial for the initiation of innate and adaptive immune responses and also important in maintaining immune tolerance to self-tissues 1 . Together with all blood cells, DCs have their ultimate origin in haematopoietic stem cells (HSCs). HSCs have the capacity to self-renew over the lifespan and also to give rise to a series of precursor cells that are progressively committed to particular cell lineages 2 . Which precursor type will actually generate DCs will depend on the availability of precursors and the immune microenvironment involved 3 . In most circumstances, myeloid precursors are the main sources to generate DCs. DCs comprise a network of subsets that differ in location, migratory pathways, detailed immunological function and dependence on stimuli for their generation, adding further layers of complexity in the coordination of immune responses 4 . The developmental pathways that lead HSCs to the different DC subsets are very important, not just in the initial establishment of the DC network, but as dynamic components of the response to microbial invasion and the maintenance of immune homeostasis 5 . Although the development and differentiation pathways have been simply mapped and much knowledge has been gained about the origins, phenotypes and functions of mouse DC subsets, examining the mechanisms of gene regulation that underlie development from HSCs to different DC subsets has the potential to improve our understanding of cell differentiation in general and to provide insights for the development of clinically relevant DC-based immunotherapy.