Identify the downstream targets of Stat3 by using an engineered mouse ES cell line treated with GCSF and LIF plus PD0325901
Ontology highlight
ABSTRACT: To identify downstream targets of Jak/Stat3 pathways without being distracted by differentiation signalings from MEK/ERK pathway, we exploited a engineered B6 cells, which stably stably expressing a chimeric receptor (GRgp-Y118F). The chimeric receptor can induce the phosphorylation of Stat3 by GCSF without activating the MEK/ERK pathway. To mimic the effect of GCSF, the chimeric B6 cells were also treated with LIF plus a selective MEK chemical inhibitor, PD0325901, to induce LIF/Jak/Stat3 but MEK/ERK pathways. mESCs starved in serum free growth medium for 6hrs were treated with GCSF or with LIF plus PD0325901 for 1hr, after which total RNA was extracted for analysis.
Project description:To identify downstream targets of Jak/Stat3 pathways without being distracted by differentiation signalings from MEK/ERK pathway, we exploited a engineered B6 cells, which stably stably expressing a chimeric receptor (GRgp-Y118F). The chimeric receptor can induce the phosphorylation of Stat3 by GCSF without activating the MEK/ERK pathway. To mimic the effect of GCSF, the chimeric B6 cells were also treated with LIF plus a selective MEK chemical inhibitor, PD0325901, to induce LIF/Jak/Stat3 but MEK/ERK pathways.
Project description:The role of FGF-MEK-ERK signalling pathway during embryonic heart development has not been fully elucidated. Here, we inhibited the pathway for 1 day using PD0325901, a MEK inhibitor, at the lateral plate mesoderm stage during cardiac differentiation of human embryonic stem cells. Cells were collected on day 2 (before PD0325901 administration), day 3 and day 8 to determine the effect of a transient FGF-MEK-ERK pathway modulation on the cardiac cell fate choice.
Project description:This experiment records the transcriptional responses of mES cells (line OG2) to FGF/ERK stimulation in the presence of LIF, to LIF/STAT3 inhibition in the presence of an FGF/ERK inhibitor, and to combined FGF/ERK stimulation / LIF/STAT3 inhibition.
Project description:This study used microarray expression analysis to identify global changes in transcript alteration in response to MEK inhibition. Genes under ERK control were identified in a panel of V600E BRAF and RTK-activated tumor cells and xenografts, using short-term inhibition of ERK activity using the MEK inhibitor PD0325901 (Pfizer). Experiment Overall Design: Cell lines growing in culture (n=12) and murine xenografts (n=2) were treated with the MEK inhibitor PD0325901 or vehicle alone as control. Paired analysis of MEK inhibited to control samples was performed for two groups of tumor cells, V600E BRAF and RTK.
Project description:The objective of this study was to investigate the roles of GSK3 inhibitor CHIR99021 and MEK inhibitor PD0325901 on 2i-adapted mouse embryonic stem cells (ESCs) in serum-free conditions.Canonical Wnt signaling supports the pluripotency of mouse ESCs but also promotes differentiation of early mammalian cell lineages. To explain these paradoxical observations, we explored the gene regulatory networks at play. Canonical Wnt signaling is intertwined with the pluripotency network comprising Nanog, Oct4, and Sox2 in mouse ESCs. In defined media supporting the derivation and propagation of mouse ESCs, Tcf3 and β-catenin interact with Oct4; Tcf3 binds to Sox motif within Oct-Sox composite motifs that are also bound by Oct4-Sox2 complexes. Further, canonical Wnt signaling up-regulates the activity of the Pou5f1 distal enhancer via the Sox motif in mouse ESCs. When viewed in the context of published studies on Tcf3 and β-catenin mutants, our findings suggest that Tcf3 counters pluripotency by competition with Sox2 at these sites, and Tcf3 inhibition is blocked by β-catenin entry into this complex. Wnt pathway stimulation also triggers β-catenin association at regulatory elements with classic Lef/Tcf motifs associated with differentiation programs. The failure to activate these targets in the presence of a MEK/ERK inhibitor essential for mouse ESC culture suggests that MEK/ERK signaling and canonical Wnt signaling combine to mouse promote ESC differentiation. Triplicates of mouse embryonic stem cells cultured under the following conditions: 1) CHIR99021+PD0325901+LIF; 2) CHIR99021+PD0325901; 3) CHIR99021; 4) PD0325901; 5) DMSO
Project description:The self-renewing pluripotent state was first captured in mouse embryonic stem cells (mESCs) over two decades ago. The standard condition requires the presence of serum and LIF, which provide growth promoting signals for cell expansion. However, there are pro-differentiation signals which destabilize the undifferentiated state of mESCs. The dual inhibition (2i) of the pro-differentiation Mek/Erk and Gsk3/Tcf3 pathways in mESCs is sufficient to establish an enhanced pluripotent “ground state” which bears features resembling the pre-implantation mouse epiblast. Gsk3 inhibition alleviates the repression of Esrrb, a transcription factor that can substitute for Nanog function in mESCs. The molecular mechanism that is mediated by Mek inhibition is however not clear. In this study, we investigate the pathway through which Mek inhibition operates to maintain ground state pluripotency. We have found that in mESCs, Kruppel-like factor 2 (Klf2) is a protein target of the Mek/Erk pathway; and that Klf2 protein is phosphorylated by Erk2 and subsequently degraded through the proteosome. It is therefore by Mek-inhibition through PD0325901 or 2i that enables the stabilization and accumulation of Klf2 to sustain ground state pluripotency. Importantly, we found that Klf2-null mESCs, while viable under LIF/Serum conditions, cannot be maintained and eventually gradually die within a few passages. Our result thus demonstrates that Klf2 is an essential factor of ground state pluripotency. Collectively, our study defines the Mek/Klf2 axis that cooperates with the Gsk3/Esrrb pathway in mediating ground state pluripotency.
Project description:The self-renewing pluripotent state was first captured in mouse embryonic stem cells (mESCs) over two decades ago. The standard condition requires the presence of serum and LIF, which provide growth promoting signals for cell expansion. However, there are pro-differentiation signals which destabilize the undifferentiated state of mESCs. The dual inhibition (2i) of the pro-differentiation Mek/Erk and Gsk3/Tcf3 pathways in mESCs is sufficient to establish an enhanced pluripotent “ground state” which bears features resembling the pre-implantation mouse epiblast. Gsk3 inhibition alleviates the repression of Esrrb, a transcription factor that can substitute for Nanog function in mESCs. The molecular mechanism that is mediated by Mek inhibition is however not clear. In this study, we investigate the pathway through which Mek inhibition operates to maintain ground state pluripotency. We have found that in mESCs, Kruppel-like factor 2 (Klf2) is a protein target of the Mek/Erk pathway; and that Klf2 protein is phosphorylated by Erk2 and subsequently degraded through the proteosome. It is therefore by Mek-inhibition through PD0325901 or 2i that enables the stabilization and accumulation of Klf2 to sustain ground state pluripotency. Importantly, we found that Klf2-null mESCs, while viable under LIF/Serum conditions, cannot be maintained and eventually gradually die within a few passages. Our result thus demonstrates that Klf2 is an essential factor of ground state pluripotency. Collectively, our study defines the Mek/Klf2 axis that cooperates with the Gsk3/Esrrb pathway in mediating ground state pluripotency.
Project description:This study used microarray expression analysis to identify global changes in transcript alteration in response to MEK inhibition. Genes under ERK control were identified in a panel of V600E BRAF and RTK-activated tumor cells and xenografts, using short-term inhibition of ERK activity using the MEK inhibitor PD0325901 (Pfizer). Experiment Overall Design: Cell lines growing in culture (n=12) and murine xenografts (n=2) were treated with the MEK inhibitor PD0325901 or vehicle alone as control. Paired analysis of MEK inhibited to control samples was performed for two groups of tumor cells, V600E BRAF and RTK. Time course analysis was performed on one representative cell line in order to first determine the optimal time point to detect changes in all cell lines.
Project description:This study used microarray expression analysis to identify global changes in transcript alteration in response to MEK inhibition. Genes under ERK control were identified in a panel of V600E BRAF and RTK-activated tumor cells and xenografts, using short-term inhibition of ERK activity using the MEK inhibitor PD0325901 (Pfizer). Keywords: paired treatment and control
Project description:Neurofibromatosis Type 1 (NF1) patients develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNST). These incurable peripheral nerve tumors result from loss of NF1 tumor suppressor gene function, causing hyperactive Ras signaling. Activated Ras controls numerous downstream effectors, but specific pathways mediating effects of hyperactive Ras in NF1 tumors are unknown. Cross-species transcriptome analyses of mouse and human neurofibromas and MPNSTs identified global negative feedback of genes that regulate Ras-Raf- MEK- extracellular signal-regulated protein kinase (ERK) signaling in both species. Nonetheless, activation of ERK was sustained in mouse and human neurofibromas and MPNST. PD0325901, a highly selective pharmacological inhibitor of MEK, was used to test whether sustained Ras-Raf-MEK-ERK signaling contributes to neurofibroma growth in the Nf1fl/fl;Dhh-cre mouse model or in NF1 patient MPNST cell xenografts. PD0325901 treatment reduced aberrantly proliferating cells in neurofibroma and MPNST, prolonged survival of mice implanted with human MPNST cells, and shrank neurofibromas in >80% of mice tested. PD0325901 also caused effects on tumor vasculature. Our data demonstrate that deregulated Ras/ERK signaling is critical for the growth of NF1 peripheral nerve tumors and provide strong rationale for testing MEK inhibitors in NF1 clinical trials.