Suppression of SHP-2 and ERK Signalling Promotes Self-Renewal of Mouse Embryonic Stem Cells

Abstract

The propagation of pluripotent mouse embryonic stem (ES) cells depends on signals transduced through the cytokine receptor subunit gp130. Signalling molecules activated downstream of gp130 in ES cells include STAT3, the protein tyrosine phosphatase SHP-2, and the mitogen-activated protein kinases, ERK1 and ERK2. A chimaeric receptor in which tyrosine 118 in the gp130 cytoplasmic domain was mutated did not engage SHP-2 and failed to activate ERKs. However, this receptor did support ES cell self-renewal. In fact, stem cell colonies formed at 100-fold lower concentrations of cytokine than the unmodified receptor. Moreover, altered ES cell morphology and growth were observed at high cytokine concentrations. These indications of deregulated signalling in the absence of tyrosine 118 were substantiated by sustained activation of STAT3. Confirmation that ERK activation is not required for self-renewal was obtained by propagation of pluripotent ES cells in the presence of the MEK inhibitor PD098059. In fact, the growth of undifferentiated ES cells was enhanced by culture in PD098059. Thus activation of ERKs appears actively to impair self-renewal. These data imply that the self-renewal signal from gp130 is a finely tuned balance of positive and negative effectors.

LIF-Induced STAT3 Signaling in Murine versus Human Embryonal Carcinoma (EC) Cells

“…Since gp80 RNA is not expressed in P19 EC cells we conclude that IL-6 does not signal due to the absence of the IL-6 binding receptor. These results are in agreement with previously published data in which addition of the soluble IL-6 receptor was required to initiate IL-6 signal transduction in mouse ES cells [35].…”

“…In the absence of ERK signaling, a sustained STAT3 activation was observed in response to gp130 receptor activation. It was concluded that ERK activation is not required for self-renewal of mouse ES cells and that the growth of undifferentiated ES cells was even enhanced in the presence of PD98059 [35]. Possibly, the effects of PD98059 on ES growth are not directly related to enhanced activation of STAT3 but rather related to enhanced effects of PD98059 on gene transcription in general, possibly by modulating the activity of the basal RNA polymerase transcription machinery.…”

“…Further experiments are required to resolve these issues, but similar effects of PD98059 on gene transcription were observed in N tera-2/D1 EC cells. Burdon et al demonstrated that mouse stem cell colonies formed at 100-fold lower LIF concentrations when the gp130 receptor was mutated at position 118 [35]. This mutant is no longer capable of binding SHP-2 and fails to activate the ERK signal transduction cascade.…”

Regulation of Nanog Expression by Phosphoinositide 3-Kinase-dependent Signaling in Murine Embryonic Stem Cells

“…Leukemia inhibitory factor (LIF) 2 plays an important role in maintaining self-renewal of murine ES (mES) cells (1,2) via activation of STAT3 (3)(4)(5)(6) and induction of c-Myc (7). LIF also activates additional signals including the Ras/ERK kinase pathway (8,9), ribosomal S 6 kinases (10), phosphoinositide 3-kinases (11), and Src kinases (12). However, whereas LIF-induced STAT3 activation promotes self-renewal, LIF-induced ERK activation appears to promote differentiation (8), leading to the proposal that the balance between STAT3 and ERK signals contributes to the determination of mES cell fate (13).…”

Chemical approaches to studying stem cell biology

“…Previous studies suggested that the ERK/mitogenactivated protein kinase (MAPK) pathway plays a negative role in mESC self-renewal [11,52]. Based on this prior knowledge, Ying et al [53] found that application of MAPK/ERK kinase (MEK) and/or fibroblast growth factor (FGF) receptor inhibitors can prevent mESC differentiation under defined conditions without LIF supplementation.…”