Suppression of epithelial–mesenchymal transition and apoptotic pathways by miR-294/302 family synergistically blocks let-7-induced silencing of self-renewal in embryonic stem cells

Abstract

The embryonic stem cell (ESC)-enriched miR-294/302 family and the somatic cell-enriched let-7 family stabilizes the self-renewing and differentiated cell fates, respectively. The mechanisms underlying these processes remain unknown. Here we show that among many pathways regulated by miR-294/302, the combinatorial suppression of epithelial–mesenchymal transition (EMT) and apoptotic pathways is sufficient in maintaining the self-renewal of ESCs. The silencing of ESC self-renewal by let-7 was accompanied by the upregulation of several EMT regulators and the induction of apoptosis. The ectopic activation of either EMT or apoptotic program is sufficient in silencing ESC self-renewal. However, only combined but not separate suppression of the two programs inhibited the silencing of ESC self-renewal by let-7 and several other differentiation-inducing miRNAs. These findings demonstrate that combined repression of the EMT and apoptotic pathways by miR-294/302 imposes a synergistic barrier to the silencing of ESC self-renewal, supporting a model whereby miRNAs regulate complicated cellular processes through synergistic repression of multiple targets or pathways.

Opposing roles of miR‐294 and MBNL 1/2 in shaping the gene regulatory network of embryonic stem cells

“…Consistent with cellular phenotypes, RT-qPCR analysis verified that mesenchymal marker Cdh2 and key transcription factors promoting epithelialto-mesenchymal transition (EMT) are upregulated in Mbnl1/2 overexpressing ESCs (Fig 6E). We and others have previously shown that miR-294 promotes ESC proliferation and G1/S transition, and inhibits apoptosis and epithelial-to-mesenchymal transition [29][30][31]43]. Therefore, these data suggest that Mbnl1/2 counteract the function of miR-294 in these processes.…”

“…Furthermore, we tested whether Mbnl1/2 can promote the expression of their targets through 3′UTR. We previously constructed luciferase reporters bearing 3′UTR of Vim, Rhoc, Tgfbr2, Cdkn1a, and Lats2 . Luciferase assay showed that MBNL proteins promoted the activity of luciferase reporters bearing 3′UTR of Tgfbr2, Cdkn1a, and Lats2 (Fig C and D).…”

Removal of Metabolic Liabilities Enables Development of Derivatives of Procaspase-Activating Compound 1 (PAC-1) with Improved Pharmacokinetics

“…67, 68 Because of this unique mechanism, PAC-1 is increasingly being used as a tool to directly activate procaspase-3 in a variety of biological settings. 66, 67, 69, 70 In addition, PAC-1 and derivatives have shown synergy with experimental therapeutics 18, 48 and with the anticancer drug paclitaxel. 55 …”

Derivatives of Procaspase-Activating Compound 1 (PAC-1) and their Anticancer Activities

“…This depletion of the labile zinc pool restores procaspase-3 enzymatic activity, allowing for cleavage of procaspase-3 to caspase-3 and the initiation of the execution pathway of apoptosis. [42] PAC-1 is now widely used as a tool compound for the induction of apoptosis [51, 59, 67, 68, 82, 83], and for the direct activation of procaspase-3 downstream of the mitochondria. [84–87] In addition, multiple independent studies have confirmed the direct procaspase-3 activation mechanism, [48, 85, 88] for example in detailed studies with selective caspase inhibitors, [85] selective caspase substrates, [48] and in Bax/Bak double knockout cells.…”