DGCR8 is essential for microRNA biogenesis and silencing of embryonic stem cell self-renewal

Abstract

The molecular controls that govern the differentiation of embryonic stem (ES) cells remain poorly understood. DGCR8 is an RNA-binding protein that assists the RNase III enzyme Drosha in the processing of microRNAs (miRNAs), a subclass of small RNAs. Here we study the role of miRNAs in ES cell differentiation by generating a Dgcr8 knockout model. Analysis of mouse knockout ES cells shows that DGCR8 is essential for biogenesis of miRNAs. On the induction of differentiation, DGCR8-deficient ES cells do not fully downregulate pluripotency markers and retain the ability to produce ES cell colonies; however, they do express some markers of differentiation. This phenotype differs from that reported for Dicer1 knockout cells, suggesting that Dicer has miRNA-independent roles in ES cell function. Our findings indicate that miRNAs function in the silencing of ES cell self-renewal that normally occurs with the induction of differentiation.

Identification of microprocessor-dependent cancer cells allows screening for growth-sustaining micro-RNAs

“…In addition, the fact that Drosha kd -PTEN kd MCF-7 cells are able to grow, even at slow rate, confirms that induction of colony growth arrest by micro-RNA depletion depends upon the cellular background. We also note that complete inhibition of the micro-RNA pathway in ES cells (Murchison et al, 2005;Wang et al, 2007;Qi et al, 2009), or adult tissues (Giraldez et al, 2005;Chong et al, 2008;Hand et al, 2009), did not induce growth arrest. We conclude that CoGAM requires efficient microprocessor knockdown in a specific cellular background.…”

“…Altogether, these results built a picture in which decreased micro-RNA expression, a feature of undifferentiated cells, has protumorigenic properties. In contrast, blocking the micro-RNA pathway of embryonic stem (ES) cells impaired their growth (Murchison et al, 2005;Wang et al, 2007;Qi et al, 2009). This global approach allowed to circumvent the often silent phenotype observed after inhibition of individual micro-RNAs (Miska et al, 2007;Wang et al, 2008), a probable consequence of the structural and functional redundancy of these regulatory RNAs.…”

PBX3 is targeted by multiple miRNAs and is essential for liver tumour-initiating cells

“…MicroRNAs (miRNA), a large family of short noncoding RNAs that negatively regulate mRNA stability or translation through imperfect base pairing with the 3 0 -untranslated regions (UTRs) of target genes, have been functionally linked to stem cells [15][16][17][18] and TICs or CSCs 19 . In fact, aberrant expression of miRNAs such as let-7, miR-34a, miR-181a, miRNA-130b in TICs has been found in a variety of tumour types.…”

Structure of the dimerization domain of DiGeorge Critical Region 8

“…12,13,16 It independently binds to pri-miRNAs [17][18][19] and makes a major contribution to their recognition by the processing machinery. In addition, proper control of DGCR8 expression and activity appears to be important for normal miRNA biogenesis.…”