Targeting protein kinase C (PKC) isoforms by the small molecule inhibitor enzastaurin has shown promising pre-clinical activity in a wide range of tumor cells. In this study, we further delineated its mechanism of action in multiple myeloma (MM) cells and found a novel role of b-catenin in regulating growth and survival of tumor cells. Specifically, inhibition of PKC leads to rapid accumulation of b-catenin by preventing the phosphorylation required for its proteasomal degradation. Microarray analysis and siRNA-mediated gene silencing in MM cells revealed that accumulated b-catenin activates early ER stress signaling via eIF2a, CHOP and p21, leading to immediate growth inhibition. Furthermore, accumulated b-catenin contributes to enzastaurin-induced cell death. Both sequential knock-down of b-catenin, c-Jun, and p73, as well as overexpression of b-catenin or p73 confirmed that accumulated b-catenin triggers c-Jun-dependent induction of p73, thereby conferring MM cell apoptosis. In summary, our data reveal a novel role of b-catenin in ER stress-mediated growth inhibition, and a new pro-apoptotic mechanism triggered by b-catenin upon inhibition of PKC isoforms. Moreover, we identify p73 as a potential novel therapeutic target in MM. Based on these and previous data, enzastaurin is currently under clinical investigation in a variety of hematologic malignancies including MM.
Targeting PKC: a novel role for beta-catenin in ER stress and apoptotic signaling.
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View SamplesThe mechanisms underlying natural variation in lifespan and ageing rate remain largely unknown.
Transcriptome analysis of a long-lived natural Drosophila variant: a prominent role of stress- and reproduction-genes in lifespan extension.
Sex, Specimen part
View SamplesNonsense-mediated mRNA decay (NMD) is a molecular pathway of mRNA surveillance that ensures rapid degradation of mRNAs containing premature translation termination codons (PTCs) in eukaryotes. Originally, NMD was thought of as a quality control pathway that targets non-functional mRNAs arising from mutations and splicing errors. More recently, NMD has been shown to also regulate normal gene expression and NMD thus emerged as one of the key post-transcriptional mechanisms of gene regulation. We have now systematically analyzed the molecular mechanism of variable NMD efficiency and used different HeLa cell strains as a model system. The results of this analysis show that NMD efficiency can be remarkably variable and represents a stable characteristic of these strains. Low NMD efficiency is shown to be functionally related to the reduced abundance of the exon junction component RNPS1 in one of the HeLa strain analyzed. Furthermore, restoration of functional RNPS1 expression, but not of NMD-inactive mutant proteins, also restores efficient NMD in the RNPS1 deficient cell line. We conclude that cellular concentrations of RNPS1 modify NMD efficiency and propose that the cell type specific co-factor availability represents a novel principle that controls NMD.
The abundance of RNPS1, a protein component of the exon junction complex, can determine the variability in efficiency of the Nonsense Mediated Decay pathway.
Sex, Disease, Subject
View SamplesTranscriptional profiling of the zebrafish embryonic host response to a systemic bacterial infection with Salmonella typhimurium (strain SL1027); comparison between traf6 knock-down and control morpholino treated embryos. Overall design: All infection experiments were performed using mixed egg clutches of ABxTL strain zebrafish. Embryos injected with traf6 morpholino or a 5bp mismatch control morpholino were staged at 27 hours post fertilization (hpf) by morphological criteria and approximately 250 cfu of DsRed expressing Salmonella bacteria were injected into the caudal vein close to the urogenital opening. As a control an equal volume of PBS was likewise injected. Pools of 20-40 infected and control embryos were collected 8 hours post infection (hpi). The whole procedure was preformed in triplicate on separate days. Total RNA of the biological triplicates was pooled using equal amounts of RNA prior to RNAseq library preparation.
Transcriptome analysis of Traf6 function in the innate immune response of zebrafish embryos.
No sample metadata fields
View SamplesResponse to allergen was studied in epithelial cells derived from allergic pantients and from healthy controls. Cells were cultured after isolation from a nasal biopsy. Cells were exposed to Housed dust mite or vessel (saline)
Primary nasal epithelium exposed to house dust mite extract shows activated expression in allergic individuals.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
GATA4 and LMO3 balance angiocrine signaling and autocrine inflammatory activation by BMP2 in liver sinusoidal endothelial cells.
Specimen part, Treatment
View SamplesLiver sinusoidal endothelial cells (LSEC) represent a unique, organ-specific type of discontinuous endothelial cells. LSEC instruct the hepatic vascular niche by paracrine-acting angiocrine factors. Recently, we have shown that LSEC-specific transcriptional regulator GATA4 induces expression of BMP2 in cultured endothelial cells (EC) in vitro. Furthermore, angiocrine Bmp2 signaling in the liver in vivo was demonstrated to control iron homeostasis. Here, we investigated GATA4-dependent autocrine BMP2 signaling in endothelial cells by gene expression profiling. GATA4 induced a large cluster of inflammatory endothelial response genes in cultured EC, which is similar to previously identified virus-induced and interferon-associated responses. Treating the cells with the BMP2 inhibitor Noggin counter-regulated the GATA4-dependent inflammatory phenotype of EC, indicating that BMP2 is indeed the major driver. In contrast to continuous EC, LSEC were less prone to activation by BMP2. Notably, GATA4-dependent induction of the inflammatory EC response gene cluster was attenuated by over-expression of the LSEC-specific transcriptional modifier LMO3 while hepatocyte activation was fully preserved, indicating conserved BMP2 synthesis. In summary, our data suggest that transcriptional counter-regulation by GATA4 and LMO3 in LSEC prevents autocrine induction of an inflammatory phenotype, while maintaining angiocrine BMP2-mediated cell communication in the liver vascular niche.
GATA4 and LMO3 balance angiocrine signaling and autocrine inflammatory activation by BMP2 in liver sinusoidal endothelial cells.
Specimen part, Treatment
View SamplesLiver sinusoidal endothelial cells (LSEC) represent a unique, organ-specific type of discontinuous endothelial cells. LSEC instruct the hepatic vascular niche by paracrine-acting angiocrine factors. Recently, we have shown that LSEC-specific transcriptional regulator GATA4 induces expression of BMP2 in cultured endothelial cells (EC) in vitro. Furthermore, angiocrine Bmp2 signaling in the liver in vivo was demonstrated to control iron homeostasis. Here, we investigated GATA4-dependent autocrine BMP2 signaling in endothelial cells by gene expression profiling. GATA4 induced a large cluster of inflammatory endothelial response genes in cultured EC, which is similar to previously identified virus-induced and interferon-associated responses. Treating the cells with the BMP2 inhibitor Noggin counter-regulated the GATA4-dependent inflammatory phenotype of EC, indicating that BMP2 is indeed the major driver. In contrast to continuous EC, LSEC were less prone to activation by BMP2. Notably, GATA4-dependent induction of the inflammatory EC response gene cluster was attenuated by over-expression of the LSEC-specific transcriptional modifier LMO3 while hepatocyte activation was fully preserved, indicating conserved BMP2 synthesis. In summary, our data suggest that transcriptional counter-regulation by GATA4 and LMO3 in LSEC prevents autocrine induction of an inflammatory phenotype, while maintaining angiocrine BMP2-mediated cell communication in the liver vascular niche.
GATA4 and LMO3 balance angiocrine signaling and autocrine inflammatory activation by BMP2 in liver sinusoidal endothelial cells.
Specimen part, Treatment
View SamplesIn order to identify transcriptional targets of ATF2, we used a recombinant adenovirus to express constitutively active ATF2 in murine hepatoblasts. Expression of GFP was the control condition.
JNK suppresses tumor formation via a gene-expression program mediated by ATF2.
Specimen part
View SamplesIn recent years, highly detailed characterization of adult bone marrow (BM) myeloid progenitors has been achieved and, as a result, the impact of somatic defects on different hematopoietic lineage fate decisions can be precisely determined. Fetal liver (FL) hematopoietic progenitor cells (HPCs) are poorly characterized in comparison, potentially hindering the study of the impact of genetic alterations on midgestation hematopoiesis. Numerous disorders, for example infant acute leukaemias, have in utero origins and their study would therefore benefit from the ability to isolate highly purified progenitor subsets. We previously demonstrated that a Runx1 distal promoter (P1)-GFP::proximal promoter (P2)-hCD4 dual-reporter mouse (Mus musculus) model can be used to identify adult BM progenitor subsets with distinct lineage preferences. In this study, we undertook the characterization of the expression of Runx1-P1-GFP and P2-hCD4 in FL. Expression of P2-hCD4 in the FL immunophenotypic Megakaryocyte-Erythroid Progenitor (MEP) and Common Myeloid Progenitor (CMP) compartments corresponded to increased granulocytic/monocytic/megakaryocytic and decreased erythroid specification. Moreover, Runx1-P2-hCD4 expression correlated with several endogenous cell surface markers' expression, including CD31 and CD45, providing a new strategy for prospective identification of highly purified fetal myeloid progenitors in transgenic mouse models. We utilized this methodology to compare the impact of the deletion of either total RUNX1 or RUNX1C alone and to determine the fetal HPCs lineages most substantially affected. This new prospective identification of FL progenitors therefore raises the prospect of identifying the underlying gene networks responsible with greater precision than previously possible. Overall design: mRNA profiles of single sorted Runx1 P2-hCD4+ Megakaryocyte Erythroid Progenitors (MEPs), Runx1 P2-hCD4- MEPs, Runx1 P2-hCD4+ Common Myeloid Progenitors (CMPs) and Runx1 P2-hCD4- CMPs from Mouse E14.5 Runx1 P2-GFP::P2-hCD4/+ Fetal Liver Samples
A novel prospective isolation of murine fetal liver progenitors to study in utero hematopoietic defects.
No sample metadata fields
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