Multifaced regulator: RNA binding proteins and their roles in hematopoiesis.

Despite the conventional definition of RNA binding proteins (RBPs) as controlling the metabolism of their bound RNAs, more and more RBPs are found to function via distinct ways in complex biological processes. With the recent discovery of transcriptional regulation activity of some RBPs, a hypothesis that RBPs could be multilayered regulators orchestrating gene expression has emerged. Hematopoiesis is a stepwise process that needs to be fine-tuned to keep the subtle balance between hematopoietic stem cell (HSC) stemness maintenance and downstream lineage commitment. Although the classic RBPs account for the posttranscriptional regulation in hematopoiesis, the importance and multiple regulatory capacities of RBPs have not been well-characterized. In this review, we summarize the recent findings of large-scale screening of novel RBPs and their novel transcriptional regulation potentials. In hematopoietic system, this kind of multifaced regulators account for nearly a half of functional RBPs. Therefore, further studies on identifying this new kind of multifaced RBPs and clarifying their regulatory mechanisms would help us better understand the precise and complex regulatory networks of gene expression in hematopoiesis.