Activation of the AKT and ERK signaling pathway is a major contributor to cell proliferation. However, the integrated regulation of this multistep process, involving signal processing, cell growth and cell-cycle progression, is poorly understood. Here we study three cell types of hematopoietic origin, in which AKT and ERK signaling is triggered by erythropoietin (Epo). We find that the different cell types exhibit distinct proliferative responses, despite sharing the molecular network for pro-proliferative signaling. Iterating quantitative experiments and mathematical modeling, we show that the cell-type-specific regulation of proliferation emerges from two sources: (1) the protein abundance patterns of signaling components that cause differential flow of signals along the AKT and ERK pathways, and (2) the differential impact of the downstream regulators for protein synthesis and for cell-cycle progression on proliferation. Our integrated mathematical model of Epo-driven proliferation explains cell-type-specific effects of targeted AKT and ERK inhibitors and correctly predicts whether their combined application results in synergy.
Protein abundance of AKT and ERK pathway components governs cell type-specific regulation of proliferation.
Sex, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
BCAT1 restricts αKG levels in AML stem cells leading to IDHmut-like DNA hypermethylation.
Cell line, Treatment
View SamplesThe branched chain amino acid (BCAA) pathway and high levels of BCAA transaminase 1 (BCAT1) have recently been associated with aggressiveness in several cancer entities. However, the mechanistic role of BCAT1 in this process remains largely uncertain. By performing high-resolution proteomic analysis of human acute myeloid leukaemia (AML) stem cell (LSC) and non-LSC populations, we found the BCAA pathway enriched and BCAT1 overexpressed in LSCs. We show that BCAT1, which transfers -amino groups from BCAAs to -ketoglutarate (KG), is a critical regulator of intracellular KG homeostasis. Next to its role in the tricarboxylic acid (TCA) cycle KG is an essential co-factor for KG-dependent dioxygenases such as EGLN1 and the TET family of DNA demethylases. Knockdown of BCAT1 in leukaemia cells caused accumulation of KG leading to HIF1a protein degradation mediated by EGLN1. This resulted in a growth and survival defect and abrogated leukaemia-initiating potential. In contrast, overexpression (OE) of BCAT1 in leukaemia cells decreased intracellular KG levels and caused DNA hypermethylation via altered TET activity. BCAT1high AMLs displayed a DNA hypermethylation phenotype similar to cases carrying mutant isocitrate dehydrogenase (IDHmut), in which TET2 is inhibited by the oncometabolite 2-hydroxyglutarate. High levels of BCAT1 strongly correlate with shorter overall survival in IDHwtTET2wt, but not IDHmut or TET2mut AMLs. Gene sets characteristic for IDHmut AMLs were enriched in IDHwtTETwtBCAT1high patient samples. BCAT1high AMLs showed robust enrichment for LSC signatures and paired sample analysis revealed a significant increase of BCAT1 levels upon disease relapse. In summary, by limiting intracellular KG, BCAT1 links BCAA catabolism to HIF1a stability and regulation of the epigenomic landscape. Our results suggest the BCAA-BCAT1-KG pathway as a therapeutic target to compromise LSC function in IDHwtTET2wt AML patients.
BCAT1 restricts αKG levels in AML stem cells leading to IDHmut-like DNA hypermethylation.
Treatment
View SamplesGene-expression microarray datasets generated as part of the Immunological Genome Project (ImmGen) for samples that use a different set of amplification reagents (Ambion WT Expression Kit, not the Affymetrix GeneChip WT cDNA Synthesis and Amplification Kits).
The tumor microenvironment shapes lineage, transcriptional, and functional diversity of infiltrating myeloid cells.
Sex, Age, Specimen part
View SamplesIn this study, by microarray we analyzed gene expression changes due to LMP1 signaling in B cells, in order to identify candidate co-stimulatory ligands that may account for the ability of LMP1-B cells to induce cytotoxic CD4+ T cell response. The identified candidate co-stimulatory ligands were further validated by other functional assays.
Signaling by the Epstein-Barr virus LMP1 protein induces potent cytotoxic CD4<sup>+</sup> and CD8<sup>+</sup> T cell responses.
Sex, Specimen part
View SamplesA number of autoimmunity-associated MHC class II proteins interact only weakly with the invariant chain-derived class II-associated invariant chain peptide (CLIP). CLIP dissociates rapidly from I-Ag7 even in the absence of DM, and this property is related to the type 1 diabetes-associated b57 polymorphism. We generated knock-in Non-obese Diabetic (NOD) mice with a single amino acid change in the CLIP segment of invariant chain in order to moderately slow CLIP dissociation from I-Ag7. These knock-in mice had a significantly reduced incidence of spontaneous type 1 diabetes and diminished islet infiltration by CD4 T cells, in particular T cells specific for fusion peptides generated by covalent linkage of proteolytic fragments within b cell secretory granules. Rapid CLIP dissociation enhanced presentation of such extracellular peptides, thus bypassing the conventional MHC class II antigen processing pathway. Autoimmunity-associated MHC class II polymorphisms therefore not only modify binding of self-peptides, but also alter the biochemistry of peptide acquisition. Overall design: Mouse pancreatic tissue was digested by collagenase, and islets were isolated and dissociated into single cells. Beta-cell-specific CD4 T cells were single-cell sorted by FACS based on tetramer labeling, and individual cells were profiled with a modified full length SMART-Seq2 protocol.
Rapid CLIP dissociation from MHC II promotes an unusual antigen presentation pathway in autoimmunity.
Specimen part, Subject
View SamplesPurpose: identify genes regulated by expression of miR-31 in primary mouse CD8 T-cells by exogenously expressing pre-miR-31 from the Plko.3g lentiviral vector. Cells infected with empty Plko.3g vectors were used as controls for infection.
The microRNA miR-31 inhibits CD8<sup>+</sup> T cell function in chronic viral infection.
Specimen part
View SamplesImmunoglobulin A (IgA) is the major secretory immunoglobulin isotype at mucosal surfaces where it regulates microbial commensalism and excludes luminal factors from contacting intestinal epithelial cells (IEC). IEC endoplasmic reticulum (ER) stress induces a polyreactive IgA response which protects from small intestinal inflammation. IEC ER stress causes expansion and activation of peritoneal B1b cells independent of microbiota and T cells that culminates in increased lamina propria and luminal IgA. Xbp1dIEC mice exhibit IEC ER stress by conditional deletion of X-box-binding protein 1 (XBP1). Here we examine single-cell transcriptomes of peritoneal cavity cells of germ-free Xbp1dIEC mice (KO) compared to littermate controls (WT). Overall design: Single-cell gene expression profiles of peritoneal cavity cells of 10-week-old germ-free Xbp1dIEC and WT mice were generated using a droplet-based system (10X Genomics Chromium).
Epithelial endoplasmic reticulum stress orchestrates a protective IgA response.
Cell line, Subject
View SamplesPancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with limited treatment options. Familial predisposition to PDAC occurs in ~10% of cases, but causative genes have not been identified in most families. Uncovering the genetic basis for PDAC susceptibility has immediate prognostic implications for families and can provide mechanistic clues to PDAC pathogenesis. Here, we perform whole-genome sequence analysis in a family with multiple cases of PDAC and identify a germline nonsense mutation in the member of RAS oncogene family-like 3 (RABL3) gene never before directly associated with hereditary cancer. The truncated mutant allele (RABL3_p.S36*) co-segregates with cancer occurrence. To evaluate the contribution of the RABL3 mutant allele in hereditary cancer, we generated rabl3 heterozygous mutant zebrafish and found increased susceptibility to cancer formation in two independent cancer models. Unbiased approaches implicate RABL3 in RAS pathway regulation: the transcriptome of juvenile rabl3 mutants reveals a KRAS upregulation signature, and affinity-purification mass spectrometry for proteins associated with RABL3 or RABL3_p.S36* identifies Rap1 GTPase-GDP Dissociation Stimulator 1 (RAP1GDS1, SmgGDS), a chaperone that regulates prenylation of RAS GTPases. Indeed, we find that RABL3_p.S36* accelerates KRAS prenylation and requires RAS proteins to promote cell proliferation. Furthermore, rabl3 homozygous mutant zebrafish develop severe craniofacial, skeletal, and growth defects consistent with human RASopathies, and these defects are partially rescued with the MEK inhibitor trametinib. Finally, we identify additional germline mutations in RABL3 that impact RAS activity in vivo and have a significant burden in a cohort of patients with developmental disorders, suggesting a role in undiagnosed RASopathies. Moreover, RABL3 is upregulated in multiple human PDAC cell lines and knockdown abrogates proliferation, consistent with a broader role for RABL3 in PDAC. Our studies identify the RABL3 mutation as a new target for genetic testing in cancer families and uncover a novel mechanism for dysregulated RAS activity in development and cancer. Overall design: WT (4 replicates) and homozygous rabl3-TR41 mutant (3 replicates) larval zebrafish at 21 days of age.
Mutations in RABL3 alter KRAS prenylation and are associated with hereditary pancreatic cancer.
Age, Specimen part, Cell line, Subject
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