Leukemia inhibitory factor (LIF) withdrawal activates mTOR signaling pathway in mouse embryonic stem cells through the MEK/ERK/TSC2 pathway

Abstract

Leukemia inhibitory factor (LIF) is indispensable to maintain the pluripotent state of mouse embryonic stem cells (ESCs), but the mechanisms underlying the role of LIF/STAT3 pathway are yet poorly understood. Here we first showed that the LIF/STAT3-regulated signaling pathway contributes to the maintenance of self-renewal and pluripotency of mouse ESCs by suppressing mTOR (mammalian target of rapamycin), which is necessary for early differentiation. When LIF is withdrawn from culture medium, the mTOR activity rapidly increases as detected by phosphorylation of its targets – ribosomal protein S6 and translation factor 4EBP1. In turn, suppression of STAT3 phosphorylation on Tyr-705 by a specific small molecule WP1066 also activates phosphorylation of the mTOR target S6 ribosomal protein. LIF removal strongly activates ERK activity indicating that ERK can be involved in either direct phosphorylation of mTOR or phosphorylation of an upstream negative regulator of mTOR – TSC1/TSC2 proteins. According to western blotting data, LIF withdrawal leads to phosphorylation of TSC2 protein thereby relieving its negative effect on mTOR activity. mTOR activation is accompanied by a decrease of pluripotent gene expression Oct-4, Nanog, Sox2 and by an augmentation of fgf5 gene expression – a marker of post-implantation epiblast. Together, these data indicate that LIF-depleted mouse ESCs undergo a transition from the LIF/STAT3-supported pluripotent state to the FGFR/ERK-committed primed-like state with expression of early differentiation markers mediated through activation of mTOR signaling.

Changes in the expression of mitochondrial morphology-related genes during the differentiation of murine embryonic stem cells

“…Second, some cell types at final stages of differentiation such as erythropoietic cells (Jensen et al, 2019; Liu et al, 2017) and hepatocytes (Das et al, 2012) have fragmented mitochondria. If ESCs were differentiated by LIF-withdrawal, various cell types will be observed among differentiated cell population (Cherepkova et al, 2016; Duval et al, 2000), including erythropoietic cells and hepatocytes. The fragmentation of mitochondria related to the specific role of cells cannot be limited to gene expression, which controls the dynamic of mitochondria.…”

“…Although many studies have evaluated the fusion and fission of mitochondria, the mechanisms and signaling pathways that determine mitochondrial dynamics are still unclear. Activation of the mammalian target of rapamycin (mTOR) pathway by the withdrawal of LIF induced mouse ESC differentiation with suppression of pluripotent genes such as Klf4, Oct4 , and Nanog (Cherepkova et al, 2016). When pluripotent stem cells differentiate, they require more energy to meet the demands of their newly acquired functions (Folmes et al, 2012)…”

Inflammation‐induced mammalian target of rapamycin signaling is essential for retina regeneration

“…This kinase is a central component of the mTOR signaling pathway and forms multiprotein complexes, mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) (Meng, Frank, & Jewell, 2018). During mammalian development, mTOR activity is required for embryonic stem cell (ESC) self-renew and differentiation (Bulut-Karslioglu et al, 2016;Cherepkova, Sineva, & Pospelov, 2016;Gomez-Salinero et al, 2016). In the nervous system, mTOR is necessary for the maintenance, proliferation, and differentiation of neural stem cell and neural progenitor cell (Lee, Lim, Park, Park, & Koh, 2016;Li et al, 2017;Romine, Gao, Xu, So, & Chen, 2015;Yang et al, 2015).…”

Effects of Epidermal Growth Factor, Glial Cell Line-Derived Neurotrophic and Leukemia Inhibitory Factor on the Proliferation and Differentiation Potential of Adipose Tissue-Derived Mesenchymal Stem Cells

“…Evidence implies that treatment of MSCs with EGF is useful for the maintenance of stem cells in the stemness state (19). After binding the receptor, LIF activates the JAK-STAT signaling pathway (20). This signaling pathway is reported to play a role in stem cells self-renewal (21).…”