Sequential EMT-MET induces neuronal conversion through Sox2

Abstract

Direct neuronal conversion can be achieved with combinations of small-molecule compounds and growth factors. Here, by studying the first or induction phase of the neuronal conversion induced by defined 5C medium, we show that the Sox2-mediated switch from early epithelial–mesenchymal transition (EMT) to late mesenchymal–epithelial transition (MET) within a high proliferation context is essential and sufficient for the conversion from mouse embryonic fibroblasts (MEFs) to TuJ+ cells. At the early stage, insulin and basic fibroblast growth factor (bFGF)-induced cell proliferation, early EMT, the up-regulation of Stat3 and Sox2, and the subsequent activation of neuron projection. Up-regulated Sox2 then induced MET and directed cells towards a neuronal fate at the late stage. Inhibiting either stage of this sequential EMT-MET impaired the conversion. In addition, Sox2 could replace sequential EMT-MET to induce a similar conversion within a high proliferation context, and its functions were confirmed with other neuronal conversion protocols and MEFs reprogramming. Therefore, the critical roles of the sequential EMT-MET were implicated in direct cell fate conversion in addition to reprogramming, embryonic development and cancer progression.

Metabolic switch and epithelial–mesenchymal transition cooperate to regulate pluripotency

“…Sequential EMT‐MET or early EMT is also observed during transdifferentiation from MEFs to functional neurons and differentiation from human ESCs to hepatocytes (He et al , ; Li et al , ). Previous RNA‐Seq results were analyzed to determine whether similar cooperation existed between early EMT and facilitated OGS in activating the expression of the five epigenetic factors (Data ref: Sun and Zheng, ; Data Ref: Hutchins et al , 2017).…”

“…Since sequential EMT‐MET has been extensively discussed during embryonic development and cancer development (Chaffer et al , ; Thiery et al , ), we hypothesize that early EMT poises the cells in a state that is beneficial for subsequent cell fate conversions (Liu et al , ; Li et al , 2014b). This hypothesis is supported by the critical roles of sequential EMT‐MET during the transition from MEFs to neuron‐like cells, the differentiation from ESCs to hepatocytes, and the conversion of human gastric epithelial cells to multipotent endodermal progenitors (Wang et al , ; He et al , ; Li et al , ).…”

“…Sequential EMT‐MET can be induced in MEFs with a new chemically defined medium (5C medium), which includes DMEM/F12 (1:1), N2 supplement (1%), basic fibroblast growth factor (bFGF, 20 ng/ml), β‐mercaptoethanol (55 μM), vitamin C (Vc, 55 μg/ml), and leukemia inhibitory factor (LIF, 1,000 unit/ml) (He et al , , ). Therefore, in the current study, we first sought to determine whether and how the 5C medium influences the reprogramming of MEFs by investigating OGS and EMT.…”

Epithelial‐mesenchymal Transition and Cancer Stem Cells: At the Crossroads of Differentiation and Dedifferentiation

“…In fact, a similar paradigm is emerging in the reprogramming field: Sequential EMT‐MET is essential for the conversion from mouse embryonic fibroblasts (MEFs) to neuronal cells (He et al, ), and sequential EMT‐MET occurs during human ESC (hESC) differentiation into definitive endoderm in vitro, where Snail plays a key role (Li et al, ). This evidence supports our proposal that early EMT/MET may poise the cells in a state more suitable for further cell fate conversion.…”

Epithelial-Mesenchymal Transition and Metabolic Switching in Cancer: Lessons From Somatic Cell Reprogramming

“…In addition, a temporary EMT-MET can increase the conversion efficiency of mouse astrocytes into induced dopamine neurons ( Cervo et al, 2017 ) and human gastric epithelial cells into multipotent endodermal progenitors ( Wang et al, 2016 ). Interestingly, in the early study of 5C medium, sequential EMT-MET was also observed during the transition of MEFs to neuron-like cells ( He et al, 2017a ). All of this evidence suggests that the mesenchymal state may be a necessary state for cell fate transition.…”