Figure 7.

Model depicting linc/circRNAs as miRNAs sponges sustain high expression of exogenous Oct4 during reprogramming. During reprogramming, the miRNAs targeting Oct4 mRNA from MEFs are highly expressed, however, the expression of exogenous Oct4 is not suppressed. Linc/circRNAs, which have complementary binding sites with the miRNAs targeting on Oct4 are also highly expressed and can counteract the activities of the miRNAs as sponges. The knockdown of the linc/circRNAs results in down-regulation of Oct4 expression, the imprinting defect at the Dlk1-Dio3 locus, decrease of reprogramming efficiency, and low-grade chimera forming iPSCs, and those can be rescued by Oct4-addback. In summary, the linc/circRNAs can improve reprogramming efficiency and quality of iPSCs by sponging miRNAs targeting on Oct4 during reprogramming.