Project description:Hypoxia, a hallmark of most solid tumors, leads to aberrations in epigenetic modifications promoting malignant tumor phenotypes, including metastatic features and stem cell-like characteristics. Aberrant DNA methylation has been considered to play an essential role during tumor progression and tightly associate with tumor malignancy. However, the mechanism by which hypoxia alters DNA methylation to promote tumor malignancy remains poorly understood. Ten-eleven translocation 1-3 (TET1-3) proteins, which catalyze the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), play a critical role in the DNA demethylation that controls different biological processes. Here we demonstrate that the expression of TET1 and TET3 is closely associated with tumor hypoxia, tumor malignancy and poor prognosis of patients with breast cancer. Hypoxia results in deregulation of TET1 and TET3, leading to breast tumor initiating cell (BTIC) properties. Mechanically, hypoxia regulates expression of TET1 and TET3 via hypoxia-inducible factor-1a (HIF-1a), thereby resulting in 5hmC genome-wide changes, which in turn leads to the upregulation of TNFa expression and activation of its downstream p38-MAPK pathway. Importantly, signal transduction through the TET-TNFa-p38-MAPK signaling axis is required for the acquisition of BTIC characteristics and chemotherapy resistance, leading to more malignant tumor phenotypes. Inhibition of the hypoxia-TET-TNFα-p38-MAPK signaling pathway results in compromised BTIC properties and tumorigenicity in vitro and in vivo, suggesting a possible therapeutic strategy.
Project description:All cells and organisms exhibit stress-coping mechanisms toensure survival. Cytoplasmic protein-RNA assemblies termedstress granules are increasingly recognized to promote cellularsurvival under stress. Thus, they might represent tumor vul-nerabilities that are currently poorly explored. The translation-inhibitory eIF2αkinases are established as main drivers ofstress granule assembly. Using a systems approach, we identifythe translation enhancers PI3K and MAPK/p38 as pro-stress-granule-kinases. They act through the metabolic master regu-lator mammalian target of rapamycin complex 1 (mTORC1) topromote stress granule assembly. When highly active, PI3K is themain driver of stress granules; however, the impact of p38becomes apparent as PI3K activity declines. PI3K and p38 thusact in a hierarchical manner to drive mTORC1 activity and stressgranule assembly. Of note, this signaling hierarchy is also presentin human breast cancer tissue. Importantly, only the recognition ofthe PI3K-p38 hierarchy under stress enabled the discovery of p38’srole in stress granule formation. In summary, we assign a new pro-survival function to the key oncogenic kinases PI3K and p38, as theyhierarchically promote stress granule formation
Project description:All cells and organisms exhibit stress-coping mechanisms to ensure survival. Cytoplasmic protein-RNA assemblies termed stress granules are increasingly recognized to promote cellular survival under stress. Thus, they might represent tumor vulnerabilities that are currently poorly explored. The translation-inhibitory eIF2α kinases are established as main drivers of stress granule assembly. Using a systems approach, we identify the translation enhancers PI3K and MAPK/p38 as pro-stress-granule-kinases. They act through the metabolic master regulator mammalian target of rapamycin complex 1 (mTORC1) to promote stress granule assembly. When highly active, PI3K is the main driver of stress granules; however, the impact of p38 becomes apparent as PI3K activity declines. PI3K and p38 thus act in a hierarchical manner to drive mTORC1 activity and stress granule assembly. Of note, this signaling hierarchy is also present in human breast cancer tissue. Importantly, only the recognition of the PI3K-p38 hierarchy under stress enabled the discovery of p38’s role in stress granule formation. In summary, we assign a new pro-survival function to the key oncogenic kinases PI3K and p38, as they hierarchically promote stress granule formation.
Project description:Altered signaling pathways typify breast cancer and serve as direct inputs to steroid hormone receptor sensors. We previously reported that phospho-Ser134-GR (pS134-GR) species are elevated in triple negative breast cancer (TNBC) and cooperate with hypoxia-inducible factors, providing a novel avenue for activation of GR in response to local or cellular stress. We probed GR regulation by factors (cytokines, growth factors) that are rich within the tumor microenvironment (TME). TNBC cells harboring endogenous wild-type (wt) or S134A-GR species were created by CRISPR/Cas knock-in and subjected to transwell migration, invasion, soft-agar colony formation, and tumorsphere assays. RNA-Seq was employed to identify pS134-GR target genes that are regulated both basally (intrinsic) or by TGFβ in the absence of exogenously added GR ligands. Regulation of selected basal and TGFβ-induced pS134-GR target genes was validated by qRT-PCR and chromatin immunoprecipitation assays. Bioinformatics tools were used to probe public data sets for expression of pS134-GR 24-gene signatures. In the absence of GR ligands, GR is transcriptionally activated via p38-dependent phosphorylation of Ser134 as a mechanism of homeostatic stress-sensing and regulated upon exposure of TNBC cells to TME-derived agents. The ligand-independent pS134-GR transcriptome encompasses TGFβ1 and MAPK signaling gene sets associated with TNBC cell survival and migration/invasion. Accordingly, pS134-GR was essential for TNBC cell anchorage-independent growth in soft-agar, migration, invasion, and tumorsphere formation, an in vitro readout of cancer stemness properties. Both pS134-GR and expression of the MAPK-scaffolding molecule 14-3-3ζ were essential for a functionally intact p38 MAPK signaling pathway downstream of MAP3K5/ASK1, indicative of a feed-forward signaling loop wherein self-perpetuated GR phosphorylation enables cancer cell autonomy. A 24-gene pS134-GR-dependent signature induced by TGFβ1 predicts shortened overall survival in breast cancer patients. Phospho-S134-GR is a critical downstream effector of p38 MAPK signaling and TNBC migration/invasion, survival, and stemness properties. Our studies define a ligand-independent role for GR as a homeostatic “sensor” of intrinsic stimuli as well as extrinsic factors rich within the TME (TGFβ1) that enables potent activation of the p38 MAPK stress-sensing pathway and nominate pS134-GR as a therapeutic target in aggressive TNBC.
Project description:Gene expression affected by TNFa was investigated, then, p38 inhibitor SB203580 was used to investigate p38 signal pathway. Experiment Overall Design: Fibroblast-like synoviocyte culture was treated with TNFa in the presence and absence of SB203580 and compared to the gene expression not treated with TNFa.
Project description:Highly pathogenic avian influenza viruses (HPAIV) induce severe inflammation in poultry and men. There is still an ongoing threat that these viruses may acquire the capability to freely spread as novel pandemic virus strains that may cause major morbidity and mortality. One characteristic of HPAIV infections is the induction of a cytokine burst that strongly contributes to viral pathogenicity. It has been suggested, that this cytokine overexpression is an intrinsic feature of infected cells and involves hyperinduction of p38 mitogen activated protein kinase (MAPK). Here we investigate the role of MAPK p38 signaling in the antiviral response against HPAIV in mice as well as in endothelial cells, the latter a primary source for cytokines during systemic infections. Global gene expression profiling of HPAIV infected endothelial cells in the presence of the MAP kinase p38-specific inhibitor SB202190 revealed, that inhibition of MAPK p38 leads to reduced expression of interferon (IFN) and other cytokines after A/Thailand/1(KAN-1)/2004 (H5N1) and A/FPV/Bratislava/79 (H7N7) infection. Furthermore, the expression of interferon stimulated genes (ISGs) after treatment with IFN or conditioned media from HPAIV infected cells was decreased when the target cells were preincubated with SB202190. Finally, promoter analysis confirmed a direct impact of p38 MAPK on the IFN-enhanceosome and ISG-promoter activity. In vivo inhibition of MAP kinase p38 greatly diminishes virus induced cytokine expression concomitant with reduced viral titers, thereby protecting mice from lethal infection. These observations show, that MAPK p38 acts on two levels of the antiviral IFN response: Initially the kinase regulates IFN induction and at a later stage MAPK p38 controls IFN signaling and thereby expression of IFN-stimulated genes. Thus, inhibition of MAP kinase p38 may be an antiviral strategy that significantly protects mice from lethal influenza via suppression of overshooting cytokine expression. HUVEC were infected with FPV in the presence or absence of a p38 MAP kinase inhibitor
Project description:Mitogen-activated protein kinases are inactivated by dual specificity phosphatases (DUSPs), whose activities are tightly regulated during cell differentiation. Using knockdown screening and single-cell transcriptional analysis, we determined that DUSP4 is the phosphatase that specifically inactivates p38 kinase for the promotion of megakaryocyte (Mk) differentiation. Mechanistically, PRMT1-mediated methylation of DUSP4 triggers its ubiquitinylation by an E3 ligase HUWE1. Interestingly, the mechanistic axis of the DUSP4 degradation and p38 activation is also associated with a transcriptional signature of immune activation in Mk cells. In the context of thrombocytopenia observed in myelodysplastic syndromes (MDS), we demonstrated that high levels of p38 MAPK and PRMT1 are associated with low platelet counts and adverse prognosis, while pharmacological inhibition of p38 MAPK or PRMT1 stimulates megakaryopoiesis. These findings provide mechanistic insights into the role of the PRMT1-DUSP4-p38 axis on Mk differentiation and present a targeting strategy for treatment of thrombocytopenia associated with MDS.
Project description:Gene expression affected by TNFa was investigated, then, p38 inhibitor SB203580 was used to investigate p38 signal pathway. Keywords: p38 signal response
Project description:Mitogen-activated protein kinases (MAPKs) regulate cardiomyocyte growth and apoptosis in response to extracellular stimulation, but the downstream effectors that mediate their pathophysiological effects remain poorly understood. We determined the targets and role of p38 MAPK in the heart in vivo by using local adenovirus-mediated gene transfer of constitutively active upstream kinase mitogen-activated protein kinase kinase 3b (MKK3bE) and wild-type p38α in rats. DNA microarray analysis of animals with cardiac-specific overexpression of p38 MAPK revealed that 264 genes were upregulated more than 2-fold including multiple genes controlling cell division, cell signaling, inflammation, adhesion and transcription. Several previously unknown p38 target genes were found. Using gel mobility shift assays we identified several cardiac transcription factors that were directly activated by p38 MAPK. Finally, we determined the functional significance of the altered cardiac gene expression profile by histological analysis and echocardiographic measurements, which indicated that p38 MAPK overexpression induced gene expression results in cell proliferation, myocardial inflammation and fibrosis. In conclusion, we defined the novel target genes and transcription factors as well as the functional effects of p38 MAPK in the heart. Expression profiling of p38 MAPK overexpression identified cell cycle regulatory and inflammatory genes critical for pathological processes in the adult heart. Experiment Overall Design: Left ventricular gene expression profiles three days after MKK3bE + WT p38α gene transfer were compared with those of Lac Z âtreated animals by screening Affymetrix Rat Expression Set 230_2.0 Arrays (there are 5 samples in both group).