Embryonic stem cell–specific microRNAs regulate the G1-S transition and promote rapid proliferation

Abstract

Dgcr8 knockout embryonic stem (ES) cells lack microprocessor activity and hence all canonical microRNAs (miRNAs). These cells proliferate slowly and accumulate in G1 phase of the cell cycle1. Here, by screening a comprehensive library of individual miRNAs in the background of the Dgcr8 knockout ES cells, we report that multiple ES cell-specific miRNAs, members of the miR-290 family, rescue the ES cell proliferation defect. Furthermore, rescued cells no longer accumulate in the G1 phase of the cell cycle. These miRNAs function by suppressing several key regulators of the G1/S transition. These results show that post-transcriptional regulation by miRNAs promotes the G1/S transition of the ES cell cycle enabling their rapid proliferation. Furthermore, our screening strategy provides an alternative and powerful approach for uncovering the role of individual miRNAs in biological processes as it overcomes the common problem of redundancy and saturation in the miRNA system.

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

“…CoGAM is independent of the p53/p21 pathway The two major CoGAM-complementing micro-RNAs, miR-19 and miR-20, have also been reported to rescue the slow growth of DGCR8 ko ES cells, in part through inhibition of the p21 G1 checkpoint protein (Wang et al, 2008). As CoGAM was accompanied by an increase in the proportion of cells in G0/G1 (Figure 2c), we hypothesized that it involved p21 activation.…”

“…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. In an elegant approach, Wang et al, (2008) went on by complementing this growth defect with individual micro-RNAs.…”

“…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. In an elegant approach, Wang et al, (2008) went on by complementing this growth defect with individual micro-RNAs. This genetic screen identified ES cell growth-sustaining micro-RNAs, and through identification of their targets, revealed essential pathways controling the progression of ES cells in the cell cycle.…”

A microRNA-Based System for Selecting and Maintaining the Pluripotent State in Human Induced Pluripotent Stem Cells

“…Therefore, miR-292 target sequences (292T) should allow expression of an associated reporter in somatic cells but not in pluripotent stem cells. To validate these assumptions, we generated LVs carrying the GFP cDNA including four tandem repeats of a sequence perfectly complementary to let7a or miR-292 (let7aT or 292T, respectively) in the 3 0 untranslated region (3 0 -UTR) [15]. Murine ESCs (R1 cell line) cultured on mouse embryonic fibroblasts (MEFs) were transduced either with a ubiquitously expressed control LV (LV.GFP) or one of the miRNA-regulated LVs (LV.GFP.let7aT and LV.GFP.292T) (Fig.…”

“…Some miRNAs are expressed in a highly tissue and developmental-stage specific pattern. In particular, a subset of miRNAs is active in embryonic stem cells (ESCs) and controls their proliferation and differentiation dynamics by influencing the expression of core regulatory factors [12][13][14][15].…”