MicroRNAs are involved in erythroid differentiation control.

MicroRNAs (miRNAs) are a class of 17-25 nucleotides non-coding RNA molecules that regulate gene expression by either translational inhibition or mRNAs degradation. We used miRNA array to characterize miRNA variation of K562 cells before and after hemin treatment. The differential expression of five miRNAs was validated by Northern blot analysis. Among them, miR-126 exhibited up-regulation while miR-103, miR-130a, miR-210, and miR-18b exhibited down-regulation after hemin induction. The same expression tendency of the five miRNAs was observed following erythroid induction of CD34+ cells derived from human cord blood. miR-103 was selected and examined for its role in erythroid differentiation. Over-expression of miR-103 in K562 could inhibit hemin-induced K562 erythroid differentiation, which suggests this miRNA may take part in erythropoiesis. We confirmed that miR-103 targeting mRNA of forkhead box J2 (FOXJ2), a transcription factor that was involved in the development of many tissues. Our results delineated the expression of miRNAs during erythroid differentiation and suggested regulatory roles of miRNAs in this process by targeting mRNAs related to erythropoiesis.