MTOR modulation induces selective perturbations in histone methylation which influence the anti-proliferative effects of mTOR inhibitors [ChIP-Seq]
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ABSTRACT: Emerging data suggest a significant cross-talk between metabolic and epigenetic programs. However, the relationship between the mechanistic target of rapamycin (mTOR) which is a pivotal regulator of cellular metabolism, and epigenetic modifications remains poorly understood. We thus explored the impact of modulating mTOR signaling on histone methylation, a well-known epigenetic modification. Our results show that constitutive mTORC1 activation caused by abrogation of TSC2 increases H3K27me3 but not H3K4me3 or H3K9me3, via 4E-BPs-mediated induction of EZH2 protein levels. Surprisingly, mTOR inhibition also induced H3K27me3 independently of TSC2. This coincided with reduced EZH2 and increased EZH1 protein levels. Notably, the ability of mTOR inhibitors to induce H3K27me3 levels was positively correlated with their anti-proliferative effects. Collectively, our findings demonstrate that both activation and inhibition of mTOR selectively increase H3K27me3 by distinct mechanisms, whereby the ability of mTOR inhibitors to induce H3K27me3 influences their anti-proliferative effects.
Project description:Emerging data suggest a significant cross-talk between metabolic and epigenetic programs. However, the relationship between the mechanistic target of rapamycin (mTOR) which is a pivotal regulator of cellular metabolism, and epigenetic modifications remains poorly understood. We thus explored the impact of modulating mTOR signaling on histone methylation, a well-known epigenetic modification. Our results show that constitutive mTORC1 activation caused by abrogation of TSC2 increases H3K27me3 but not H3K4me3 or H3K9me3, via 4E-BPs-mediated induction of EZH2 protein levels. Surprisingly, mTOR inhibition also induced H3K27me3 independently of TSC2. This coincided with reduced EZH2 and increased EZH1 protein levels. Notably, the ability of mTOR inhibitors to induce H3K27me3 levels was positively correlated with their anti-proliferative effects. Collectively, our findings demonstrate that both activation and inhibition of mTOR selectively increase H3K27me3 by distinct mechanisms, whereby the ability of mTOR inhibitors to induce H3K27me3 influences their anti-proliferative effects.
Project description:Tuberous sclerosis complex (TSC) is a rare genetic disease caused by abnormal of TSC1 or TSC2 gene. Our previous data deduced that IQGAP2 can be one of the genes potentially responsible for non-TSC1 or TSC2 mutation TSC patients. To investigate the pathogenesis of IQGAP2 in TSC, we performed global transcriptome, proteome, and phosphoproteome analyses and found the alter of genes related to mTOR signaling pathway in IQGAP2 knockdown cells. In addition, we found that knockdown of IQGAP2 resulted in increased cell proliferation and enhanced the phosphorylation level of AKT and S6K by functional analysis, meanwhile, the AKT and mTOR inhibitors can partially rescue cell abnormal proliferation by decreasing hyperphosphorylation. Our data revealed a potential connection between mTOR signaling pathway and aberrant cell proliferation in IQGAP2 knockdown cells, and provide a new latent therapeutic strategy for non-TSC1 or TSC2 mutation patients.
Project description:The TSC/mTOR (tuberous sclerosis complex/mammalian target of rapamycin) pathway has a central role in cell growth and is involved in human tumorigenesis. Here, we demonstrate an unexpected role of TSC2 and mTOR in regulating key inflammatory cytokines in monocytes, macrophages, and dendritic cells after bacterial stimulation. mTOR deficiency promoted IL-12/IL-23 and blocked IL-10 production via the transcription factor NF-kB. Conversely, loss of TSC2, a key negative regulator of mTOR, led to reduced NF-kB activity, limited IL-12 but enhanced IL-10 production. Transcriptional profiling demonstrated that mTOR additionally regulated many mediators important for inflammation and immunoregulation including PD-L1, CCR5, CCL22, and MCP-1. mTOR inhibition in vivo rescued susceptible mice from a lethal Listeria monocytogenes infection by modulating IL-12/IL-10 production. These data identify the TSC2/mTOR pathway as a novel pathway in innate immune responses by controlling NF-kB with profound clinical implications for infectious diseases, cancer, or transplantation. Keywords: inflammatory response of monocytes to LPS and rapamycin 107 CD14+ monocytes from four different donors were stimulated with 100 ng/ml LPS with or without 100 nM rapamycin for 4 hours. Cells were harvested, washed and pelleted and frozen at â80° C. Sample preparation and hybridization to a PIQORTM Immunology Microarray Human Antisense (quadrupled cDNA fragments for 1070 genes) was performed at the Miltenyi Microarray Service Unit. In brief, RNA was extracted with the TRIzol method (Sigma-Aldrich) and 1mg of total RNA was linear amplified by T7 polymerase. Total RNA from the LPS treated cells were Cy3 labeled, LPS and rapamycin treated cells were Cy5 labeled; both samples of a donor were hybridized on a single microarray. Only genes with signal intensities >2-fold above average background in one of the two channels were regarded as expressed.
Project description:The TSC/mTOR (tuberous sclerosis complex/mammalian target of rapamycin) pathway has a central role in cell growth and is involved in human tumorigenesis. Here, we demonstrate an unexpected role of TSC2 and mTOR in regulating key inflammatory cytokines in monocytes, macrophages, and dendritic cells after bacterial stimulation. mTOR deficiency promoted IL-12/IL-23 and blocked IL-10 production via the transcription factor NF-kB. Conversely, loss of TSC2, a key negative regulator of mTOR, led to reduced NF-kB activity, limited IL-12 but enhanced IL-10 production. Transcriptional profiling demonstrated that mTOR additionally regulated many mediators important for inflammation and immunoregulation including PD-L1, CCR5, CCL22, and MCP-1. mTOR inhibition in vivo rescued susceptible mice from a lethal Listeria monocytogenes infection by modulating IL-12/IL-10 production. These data identify the TSC2/mTOR pathway as a novel pathway in innate immune responses by controlling NF-kB with profound clinical implications for infectious diseases, cancer, or transplantation. Keywords: inflammatory response of monocytes to LPS and rapamycin
Project description:Resistance to immunotherapy continues to impair common clinical benefit. Here, we uncover an important role for Tuberous Sclerosis 2 (TSC2) in tumor susceptibility to killing by cytotoxic T lymphocytes, both in in vitro and in vivo. TSC2-depleted tumor cells show disruption of mTOR regulation upon CTL attack, which was associated by enhanced cell death responses. Mechanistically, we observed induced TRAIL receptor expression in TSC2-depleted cells, causing enhanced TRAIL sensitivity of tumor cells. Corroborating these data clinically, a negative correlation between TSC2 expression and TRAIL signaling was found in TCGA patient cohorts. Moreover, a lower TSC2 immune response signature was observed in melanoma patients responding to immune checkpoint blockade. Our study reveals a critical role for TSC2 in cancer immune response by crosstalk between TSC2-mTOR and TRAIL signaling, and merits therapeutic exploration of this pathway for immuno-oncology.
Project description:MTOR modulation induces selective perturbations in histone methylation which influence the anti-proliferative effects of mTOR inhibitors
Project description:Sandhoff disease, a lysosomal storage disorder, is caused by pathogenic variants in the HEXB gene, resulting in the loss of β-hexosaminidase activity and accumulation of GM2 ganglioside and GA2 glycolipid. This accumulation occurs primarily in neurons, and leads to progressive neurodegeneration through a largely unknown process. Lysosomal storage diseases often exhibit dysfunctional mTOR signaling, a pathway crucial for proper neuronal development and function. In this study, Sandhoff disease model mice exhibited reduced mTOR signaling in the brain. To test if restoring mTOR signaling could improve the disease phenotype, we genetically reduced expression of the mTOR inhibitor Tsc2 in these mice. Sandhoff disease mice with reactivated mTOR signaling displayed increased survival rates and motor function, especially in females, increased dendritic-spine density, and reduced neurodegeneration. Tsc2 reduction also partially rescued aberrant synaptic function–related gene expression. These findings imply that enhancing mTOR signaling could be a potential therapeutic strategy for lysosomal-based neurodegenerative diseases
Project description:The ground state of pluripotency is defined as a basal proliferative state free of epigenetic restriction, represented by mouse embryonic stem cells (ESCs) cultured with two kinase inhibitors (so-called “2i”). Through comparison with serum-grown ESCs, we identify epigenetic features characterizing 2i ESCs by proteome profiling of chromatin including post-translational histone modifications. The most prominent difference is H3K27me3 and its enzymatic writer complex PRC2 that are highly abundant on eu- and heterochromatin in 2i ESCs, with H3K27me3 redistributing outside canonical PRC2 targets in a CpG-dependent fashion. Using PRC2-deficient 2i ESCs, we identify epigenetic crosstalk with H3K27me3, including significant increases in H4 acetylation and DNA methylation. This suggests that the unique H3K27me3 configuration protects 2i ESCs from preparation to lineage priming. Interestingly, removal of DNA methylation in PRC2-deficient 2i ESCs lacking H3K27me3 using 5-azacytidine hardly affected ESC viability and transcriptome, showing that ESCs are independent of both major repressive epigenetic marks.
Project description:Overexpression of EZH2 in estrogen receptor negative (ER-) breast cancer promotes metastasis. EZH2 has been mainly studied as the catalytic component of the Polycomb Repressive Complex 2 (PRC2) that mediates gene repression by trimethylating histone H3 at lysine 27 (H3K27me3). However, how EZH2 drives metastasis despite the low H3K27me3 levels observed in ER- breast cancer is unknown. We have shown that in human invasive carcinomas and distant metastases, cytoplasmic EZH2 phosphorylated at T367 is significantly associated with ER- disease and low H3K27me3 levels. Here, we explore the interactome of EZH2 and of a phosphodeficient mutant EZH2_T367A. We identified novel interactors of EZH2, and identified interactions that are dependent on the phosphorylation and cellular localization of EZH2 that may play a role in EZH2 dependent metastatic progression.
Project description:MTOR modulation induces selective perturbations in histone methylation which influence the anti-proliferative effects of mTOR inhibitors [ChIP-Seq]