C/EBPb is an auto-repressed protein that becomes posttranslationally activated by Ras-MEK-ERK signalling. C/EBPb is required for oncogene-induced senescence (OIS) of primary fibroblasts, but also displays pro-oncogenic functions in many tumour cells. Here, we show that C/EBPb activation by H-RasV12 is suppressed in immortalized/transformed cells, but not in primary cells, by its 30 untranslated region (30UTR). 30UTR sequences inhibited Ras-induced cytostatic activity of C/EBPb, DNA binding, transactivation, phosphorylation, and homodimerization, without significantly affecting protein expression. The 30UTR suppressed induction of senescence-associated C/EBPb target genes, while promoting expression of genes linked to cancers and TGFb signalling. An AU-rich element (ARE) and its cognate RNA-binding protein, HuR, were required for 30UTR inhibition. These components also excluded the Cebpb mRNA from a perinuclear cytoplasmic region that contains activated ERK1/2, indicating that the site of C/EBPb translation controls de-repression by Ras signalling. Notably, 30UTR inhibition and Cebpb mRNA compartmentalization were absent in primary fibroblasts, allowing Ras-induced C/EBPb activation and OIS to proceed. Our findings reveal a novel mechanism whereby non-coding mRNA sequences selectively regulate C/EBPb activity and suppress its anti-oncogenic functions.
3'UTR elements inhibit Ras-induced C/EBPβ post-translational activation and senescence in tumour cells.
Cell line
View SamplesThe integrated stress response (ISR) controls cellular adaptations to nutrient deprivation, redox imbalances and ER stress. ISR genes are upregulated in stressed cells, primarily by the bZIP transcription factor ATF4 through its recruitment to cis-regulatory C/EBP:ATF response elements (CAREs) together with a dimeric partner of uncertain identity. Here we show that C/EBP:ATF4 heterodimers, but not C/EBP:ATF4 dimers, are the predominant CARE binding species in stressed cells. C/EBP and ATF4 associate with genomic CAREs in a mutually-dependent manner and co-regulate many ISR genes. By contrast, the C/EBP family members C/EBP and CHOP were largely dispensable for induction of stress genes. Cebpg/ MEFs proliferate poorly and exhibit oxidative stress due to reduced glutathione levels and impaired expression of several glutathione biosynthesis pathway genes. Cebpg/ mice (C57BL/6 background) display reduced body size and microphthalmia, similar to ATF4-null animals. In addition, C/EBP-deficient newborns die from atelectasis and respiratory failure which can be mitigated by in utero exposure to the anti-oxidant, N-acetyl-cysteine. Cebpg/ mice on a mixed strain background show improved viability but, upon aging, develop significantly fewer malignant solid tumors compared to WT animals. Our findings identify C/EBP as a novel anti-oxidant regulator and an obligatory ATF4 partner that controls redox homeostasis in normal and cancerous cells.
C/EBPγ Is a Critical Regulator of Cellular Stress Response Networks through Heterodimerization with ATF4.
Specimen part
View SamplesC/EBP is an important regulator of oncogene-induced senescence (OIS). Here we show that C/EBP, a heterodimeric partner of C/EBP whose biological functions are not well understood, inhibits cellular senescence. Cebpg-/- MEFs proliferated poorly, entered senescence prematurely, and expressed a pro-inflammatory gene signature, including elevated levels of senescence-associated secretory phenotype (SASP) genes whose induction by oncogenic stress requires C/EBP. The senescence-suppressing activity of C/EBP required its ability to heterodimerize with C/EBP. Covalently linked C/EBP homodimers (~) inhibited the proliferation and tumorigenicity of RasV12-transformed NIH3T3 cells, activated SASP gene expression, and recruited the CBP co-activator in a Ras-dependent manner, whereas ~ heterodimers lacked these capabilities and efficiently rescued proliferation of Cebpg-/- MEFs. C/EBP depletion partially restored growth of C/EBP-deficient cells, indicating that the increased levels of C/EBP homodimers in Cebpg-/- MEFs inhibit proliferation. The proliferative functions of C/EBP are not restricted to fibroblasts, as hematopoietic progenitors from Cebpg-/- bone marrow also displayed impaired growth. Furthermore, high CEBPG expression correlated with poorer clinical prognoses in several human cancers, and C/EBP depletion decreased proliferation and induced senescence in lung tumor cells. Our findings demonstrate that C/EBP neutralizes the cytostatic activity of C/EBP through heterodimerization, which prevents senescence and suppresses basal transcription of SASP genes.
C/EBPγ suppresses senescence and inflammatory gene expression by heterodimerizing with C/EBPβ.
Specimen part
View SamplesWe studied whether the accumulation of lipids in the fasted kidney are derived from lipoproteins or (non-esterified fatty acids) NEFAs. With overnight fasting, kidneys accumulated triglyceride, but had reduced levels of ceramide and glycosphingolipid species. Fasting led to a nearly 5-fold increase in kidney uptake of plasma [14C]oleic acid. Increasing circulating NEFAs using a ß adrenergic receptor agonist caused a 15-fold greater accumulation of lipid in the kidney, while mice with reduced NEFAs due to adipose tissue deficiency of adipose triglyceride lipase had reduced triglycerides. Cluster of differentiation (Cd)36 mRNA increased 2-fold, and angiopoietin-like 4 (Angptl4), an LPL inhibitor, increased 10-fold. Fasting-induced kidney lipid accumulation was not affected by inhibition of LPL with poloxamer 407 or by use of mice with induced genetic LPL deletion. Despite the increase in CD36 expression with fasting, genetic loss of CD36 did not alter fatty acid uptake or triglyceride accumulation. Our data demonstrate that fasting-induced triglyceride accumulation in the kidney correlates with the plasma concentrations of NEFAs, but is not due to uptake of lipoprotein lipids and does not involve the fatty acid transporter, CD36. Overall design: Mice (n=4-5/group) were either fasted for 16 hours or fed ad libitum. Kidneys were removed and snap frozen. RNA was extracted for sequencing.
Kidney triglyceride accumulation in the fasted mouse is dependent upon serum free fatty acids.
Sex, Cell line, Treatment, Subject
View SamplesTumor-associated blood vessels differ from normal vessels at the morphological and molecular level. Proteins that are only present on tumor vessels may serve as biomarkers and as therapeutic targets for inhibition of angiogenesis in cancer. Comparing the transcriptional profiles of blood vascular endothelium from human invasive bladder cancer and from normal bladder tissue, we found several markers that could serve as novel biomarkers or therapeutic targets.
Endocan is upregulated on tumor vessels in invasive bladder cancer where it mediates VEGF-A-induced angiogenesis.
Sex, Disease stage
View SamplesPhytophthora root and stem rot (PRR) of soybean, caused by Phytophthora sojae, is effectively controlled by Rps genes in soybean. Rps genes are race-specific, yet the mechanism of resistance, as well as susceptibility, remains largely unclear. Taking advantage of RNA-seq technology, we sequenced the transcriptomes of 10 near isogenic lines (NIL), each with a unique Rps gene, and the recurrent susceptible parent 'Williams'. A total of 4330 differentially expressed genes (DEGs) were identified in 'Williams' while 2075 to 5499 DEGs were identified in each NIL. Comparisons between the NILs and 'Williams' allowed classification of two major groups of DEGs of interest: incompatible reaction associated genes (IRAGs) and compatible reaction associated genes (CRAGs). Hierarchical cluster analysis divided NILs into three clusters: Cluster I (Rps1-a), Cluster II (Rps1-b, 1-c and 1-k) and Cluster III (Rps3-a, 3-b, 3-c, 4, 5, and 6). Heatmap analysis, along with GO analysis suggested that the diversity of clusters for NILs were likely due to variation of the number of DEGs and the intensity of gene expression, rather than functional differentiation. Further analysis suggested that transcription factors might play pivotal role in determination of the cluster pattern, and that WRKY family were strongly associated with incompatible reactions. Analysis of IRAGs and CRAGs with putative functions suggested that the regulation of many phytohormone signaling pathways were associated with incompatible or compatible interactions with potential crosstalk between each other. As such, our study provides an in depth view of both incompatible and compatible interactions between soybean and P. sojae, which provides further insight into the mechanisms involved in host-pathogen interactions. Overall design: 22 samples were sequenced, 11 inoculated with P. sojae, the other 11 were mock-inoculated
Molecular response to the pathogen Phytophthora sojae among ten soybean near isogenic lines revealed by comparative transcriptomics.
Specimen part, Subject
View SamplesThree-dimensional (3D) culture of hepatocytes leads to improved and prolonged synthetic and metabolic functions, but the underlying molecular mechanisms were unknown. In order to investigate the molecular mechanisms underlying 3D cell-cell interactions in maintaining hepatocyte differentiated functions ex vivo, microarray analyses were performed on primary mouse hepatocytes cultured either as monolayers on tissue culture dishes (TCD) or as 3D aggregates in rotating wall vessel (RWV) bioreactors.
Molecular mechanisms underlying the enhanced functions of three-dimensional hepatocyte aggregates.
Sex
View SamplesAnalysis of the abh1 mutant Arabidopsis plants following treatment with 50 uM abscisic acid (ABA). ABH1 encodes the large (80kDa) subunit of the nuclear mRNA cap binding complex and affects early ABA signal transduction events (Hugouvieux et al., 2001, Cell 106, 477).
mRNA cap binding proteins: effects on abscisic acid signal transduction, mRNA processing, and microarray analyses.
No sample metadata fields
View SamplesEssential fatty acids (FA) are not only energy-rich molecules; they are also an important component of the membrane bilayer and recently have been implicated in induction of fatty acid synthase (FAS) and other genes. Using gene chip analysis, we have found that arachidonic acid (AA), an omega-6 fatty acid, induced 11 genes that are regulated by NFkappaB. We verified gene induction by omega-6 fatty acids including COX2, IKBA, NFKB, GMCSF, IL1B, CXCL1, TNFA, IL6, LTA, IL8, PPARG, and ICAM1 using qRTPCR. PGE2 synthesis was increased within 5min of addition of AA. Analysis of upstream signal transduction showed that within 5min of FA addition, phophatidylinositol 3-kinase (PI3K) was significantly activated followed by activation of Akt at 30min. ERK1 and 2, p38, and SAPK/JNK were not phosphorylated after omega-6 FA addition. Thirty minutes after FA addition, we found a significant 3-fold increase in translocation of NFkappaB transcription factor to the nucleus. Addition of non-steroidal anti-inflammatory drug (NSAID) caused a decrease in cox-2 protein synthesis, PGE2 synthesis as well as inhibition of PI3K activation. We have previously shown that AA induced proliferation is also blocked (P<0.001) by PI3K inhibitor LY294002. LY294002 also significantly inhibited the AA induced gene expression of COX2, IL1B, GMCSF, and ICAM1. Taken together, the data suggests that AA via conversion to PGE2 plays an important role in stimulation of growth related genes and proliferation via PI3K signaling and NFkappaB translocation to the nucleus.
Arachidonic acid activates phosphatidylinositol 3-kinase signaling and induces gene expression in prostate cancer.
No sample metadata fields
View SamplesWe report the application of RNA-seq analysis for high-throughput profiling of murine lungs infected with Aspergillus fumigatus. We compared the lung transcription of wildtype murine lungs and lungs from mice deficient in metabolic cytokine adiponectin. Overall design: Examination of 2 different mice strain and comparison of lung transcripts in response to Aspergillus fumigatus infection.
The Metabolic Cytokine Adiponectin Inhibits Inflammatory Lung Pathology in Invasive Aspergillosis.
Specimen part, Cell line, Subject
View Samples