Hematopoietic stem cells (HSCs), which reside in bone marrow niches, are exposed to low levels of oxygen and follow an oxygen gradient throughout their differentiation. Hypoxia-inducible factors (HIFs) are the main factors regulating the cell response to oxygen variation. Recent studies using conditional knockout mouse models have unveiled a major role of HIF-1a in the maintenance of murine HSCs, however the role of HIF-2a is still unclear. Here, we show that knockdown of HIF-2a and to a much lower extent, HIF-1a impedes the long-term repopulating ability of human CD34+ umbilical cord blood derived cells. The defects observed in hematopoietic stem and progenitor cell (HSPC) function after HIF-2a knockdown was due to an increase in the production of reactive oxygen species (ROS), which increases the endoplasmic reticulum (ER) stress in HSPCs and triggers apoptosis by the activation of the unfolded-protein-response (UPR) pathway. Importantly, HIF-2a deregulation also resulted in a significant decrease of engraftment of human acute myeloid leukemia (AML) cells. Overall, our data demonstrates a key role of HIF-2a in the maintenance of human HSPCs and in the survival of primary AML cells.
HIF-2α protects human hematopoietic stem/progenitors and acute myeloid leukemic cells from apoptosis induced by endoplasmic reticulum stress.
Specimen part
View SamplesWe used a modification of GINI analysis to identify genes containing premature translation termination codons (PTC) generated by nonsense or frameshift mutations in prostate cancer cell lines. The analysis was performed in two steps. In the first step nonsense mediated mRNA decay (NMD) was inhibited in prostate cancer cell lines using incubation with medium containing caffeine for 4 hours. Gene expression analysis of caffeine treated or untreated cells after this step detects mRNA accumulation that takes place for genes containing PTC and as well as for genes that show induction of transciption due to stress caused by NMD inhibition. In the second step either both transcription and NMD or transcription only are blocked by incubating cell in a medium containing either both actinomycin D and caffeine or actinomacin D only for 4 hours. Gene expression analysis after this second step detects mRNA degradation for genes containing PTC as well as for genes that show induction of transciption due to stress caused by NMD inhibition. The efficiency of mRNA degradation for genes containing PTC during this step depends on whether NMD is inhibited or not. The efficiency of mRNA degradation for stress response genes does not depend on whether NMD is inhibited or not.
Par-3 partitioning defective 3 homolog (C. elegans) and androgen-induced prostate proliferative shutoff associated protein genes are mutationally inactivated in prostate cancer cells.
Cell line, Treatment
View SamplesInhibition of the nonsense mediated decay (NMD) mechanism in cells results in stabilization of transcripts carrying premature translation termination codons. A strategy referred to as gene indentification by NMD inhibition (GINI) has been proposed to identify genes carrying nonsense mutations (Noensie & Dietz, 2001). Genes containing frameshift mutations in colon cancer cell line have been identifying mutatnt genes using GINI, we have now further improved the strategy. In this approach, inhibition of NMD with emetine is complemented with inhibiting NMD by blocking the phosphorylation of the hUpf1 protein with caffeine. In addition, to enhance the GINI strategy, comparing mRNA level alterations produced by inhibiting transcription alone or inhbiiting transcription together with NMD following caffeine pretreatment were used for the efficient identification of false positives produced as a result of stress response to NMD inhibition. To demonstrate the improved efficiency of this approach, we analyzed colon cancer cell lines showing microstellite instability. Bi-allelic inactivating mutations were found in the FXR1, SEC1L1, NCOR1, BAT3, PHD14, ZNF294, C190ORF5 genes as well as genes coding for proteins with yet unknown functions.
Identifying candidate colon cancer tumor suppressor genes using inhibition of nonsense-mediated mRNA decay in colon cancer cells.
No sample metadata fields
View SamplesCD24, or heat stable antigen, is a cell surface sialoglycoprotein expressed on immature cells that disappears after the cells have reached their final differentiation stage. CD24 may be important in human embryonic kidney epithelial cell differentiation. In mice, CD24 expression is up-regulated in the early metanephros and localized to developing epithelial structures but the role and expression of CD24 in the developing human kidney has not been well described. In normal human fetal kidneys from 8 to 38 weeks gestation, CD24 expression was up-regulated and restricted to the early epithelial aggregates of the metanephric blastema and to the committed proliferating tubular epithelia of the S-shape nephron; however individual CD24+ cells were identified in the interstitium of later gestation and postnatal kidneys. In freshly isolated cells, FACS analysis demonstrated distinct CD24+ and CD24+133+ cell populations, constituting up to 16% and 14% respectively of the total cells analyzed. Isolated and expanded CD24+ clones displayed features of an epithelial progenitor cell line. Early fetal urinary tract obstruction resulted in an upregulation of CD24 expression, both in developing epithelial structures of early gestation kidneys and in the cells of the injured tubular epithelium of the later gestation kidneys. These results highlight the cell specific expression of CD24 in the developing human kidney and dysregulation in fetal urinary tract obstruction.
Ontogeny of CD24 in the human kidney.
Age, Specimen part
View SamplesAffymetrix MG430 2.0 expression levels of wild-type (STHdhQ7/Q7), 3NP-treated wild-type (STHdhQ7/Q7+3-NP), and mutant (STHdhQ111/Q111) striatal cells
Unbiased gene expression analysis implicates the huntingtin polyglutamine tract in extra-mitochondrial energy metabolism.
No sample metadata fields
View SamplesSnapshot of translation in mammalian cells that are depleted of polyamines or replete with polyamines. Hek293T cells treated with DFMO or Spermidine. Overall design: DFMO vs. Spermidine treatment
Polyamine Control of Translation Elongation Regulates Start Site Selection on Antizyme Inhibitor mRNA via Ribosome Queuing.
Disease, Treatment, Subject
View SamplesGrainyhead genes are involved in wound healing and developmental neural tube closure. In light of the high degree of similarity between the epithelial-mesenchymal transitions (EMTs) occurring in wound healing processes and the cancer stem cell-like compartment of tumors, including TGF--dependence, we investigated the role of a Grainyhead gene (GRHL2) in oncogenic EMT. Grainyhead was specifically down-regulated in the claudin-low subclass of mammary tumors and in the basal-B subclass of breast cancer cell lines. Functionally, GRHL2 suppressed TGF--induced, Twist-induced or spontaneous EMT, enhanced anoikis-sensitivity, and suppressed mammosphere generation in mammary epithelial cells. These effects were mediated, in part, by its suppression of ZEB1 expression, through direct repression of the ZEB1 promoter. GRHL2 also inhibited Smad-mediated transcription, and up-regulated mir200b/c as well as the TGF- receptor antagonist, BMP2. The expression of GRHL2 in the breast cancer cell line MDA-MB-231 triggered a mesenchymal-to-epithelial transition and sensitized the cells to anoikis. These results indicate that GRHL2 is a suppressor of the oncogenic EMT.
Suppression of the epithelial-mesenchymal transition by Grainyhead-like-2.
Specimen part
View SamplesThe zinc finger factor Insm1 is known to regulate differentiation of pancreatic cells during development, Here we show that Insm1 is essential for the maintenance of functionally mature pancreatic cells in mice.
Insm1 cooperates with Neurod1 and Foxa2 to maintain mature pancreatic β-cell function.
No sample metadata fields
View Samples4 week old Arabidopsis plants, of ecotype Columbia, SALK_084897 or SAIL_303_D08 were either grown under normal conditions or grown under normal conditions for before having a moderate light and drought treatment applied. Light and drought treatment was applied by withholding water for 5 days prior to transfer to 300 uE m-2 s-1 light conditions. Samples were collected after 3 days of treatment or for the same age plants grown under normal conditions.
The absence of ALTERNATIVE OXIDASE1a in Arabidopsis results in acute sensitivity to combined light and drought stress.
No sample metadata fields
View SamplesWe report a genome-wide survey of early responses of the mouse heart transcriptome to acute myocardial infarction (AMI). For three regions of the left ventricle (LV), namely ischemic/infarcted tissue (IF), the surviving LV free wall (FW) and the interventricular septum (IVS), 36,899 transcripts were assayed at six time points from 15 min to 48 h post-AMI in both AMI and sham surgery mice. For each transcript, temporal expression patterns were systematically compared between AMI and sham groups, which identified 515 AMI-responsive genes in IF tissue, 35 in the FW, 7 in the IVS, with three genes induced in all three regions. Using the literature, we assigned functional annotations to all 519 nonredundant AMI-induced genes and present two testable models for central signaling pathways induced early post-AMI. First, the early induction of 15 genes involved in assembly and activation of the activator protein-1 (AP-1) family of transcription factors implicates AP-1 as a dominant regulator of earliest post-ischemic molecular events. Second, dramatic increases in transcripts for arginase 1 (ARG1), the enzymes of polyamine biosynthesis and protein inhibitor of nitric oxide synthase (NOS) activity indicates that NO production may be regulated, in part, by inhibition of NOS and coordinate depletion of the NOS substrate, L-arginine. ARG1 was the single most highly induced transcript in the database (121-fold in IF region) and its induction in heart has not been previously reported.
Earliest changes in the left ventricular transcriptome postmyocardial infarction.
No sample metadata fields
View Samples