MicroRNA regulation of neutrophil function

Neutrophil maturation in the bone marrow, granulopoiesis, is a tightly regulated process governed by a temporal and successive expression of transcription factors and appropriate stimulation by cytokines from the surrounding stromal tissue of the bone marrow. Observations published over the last decade have, however, made it increasingly clear that posttranscriptional fine-tuning of protein expression by microRNAs (miRNAs) also plays a very important role in this process. In this chapter the influence of miRNAs on normal neutrophil development and biology is reviewed. The majority of miRNAs alter their expression profile at the point in granulopoiesis where proliferation ceases and terminal differentiation commences indicating a major role of miRNAs in fine-tuning of cell cycle regulatory proteins and transcription factors governing this transition. Some miRNAs are induced by external stimuli of the mature neutrophil and act to fine-tune the innate immune action of the cell.