Project description:IRE1a is a critical modulator of the unfolded protein response. Its RNAse activity generates the mature transcript for the XBP1 transcription factor and also degrades other ER associated mRNAs in a process termed Regulated IRE1a Dependent mRNA Decay or RIDD. To determine if IRE1a is critical in the response to oncogenic Ras we used ShRNA to knockdown Ire1a or Xbp1 in primary mouse epidermal keratinocytes transduced with a v-HRAS retrovirus.
Project description:IRE1a and XBP1 are key regulators of the unfolded protein response (UPR). XBP1 ablation causes profound hypolipidemia in mice, and triggers feedback activation of its upstream enzyme IRE1a, instigating regulated IRE1-dependent decay (RIDD), an mRNA degradation mechanism dependent on IRE1a's endoribonuclease activity. Comprehensive microarray analysis of XBP1 and/or IRE1a deficient liver identified genes involved in lipogenesis and lipoprotein metabolism as RIDD substrates, which might contribute to the suppression of plasma lipid levels by activated IRE1a. To identify RIDD substrate mRNAs and direct XBP1 targets in the liver, we performed a comprehensive comparative microarray analysis of three groups of RNA samples: WT and XBP1 deficient mice, WT and IRE1a deficient mice untreated or injected with tunicamycin, and XBP1 deficient mice injected with luciferase or IRE1a siRNA.
Project description:IRE1a and XBP1 are key regulators of the unfolded protein response (UPR). XBP1 ablation causes profound hypolipidemia in mice, and triggers feedback activation of its upstream enzyme IRE1a, instigating regulated IRE1-dependent decay (RIDD), an mRNA degradation mechanism dependent on IRE1a's endoribonuclease activity. Comprehensive microarray analysis of XBP1 and/or IRE1a deficient liver identified genes involved in lipogenesis and lipoprotein metabolism as RIDD substrates, which might contribute to the suppression of plasma lipid levels by activated IRE1a.
Project description:The discovery that activation of the Hras gene was the driver mutation for tumor development in mouse skin treated with 7,12-dimethylbenz(a)anthracene illuminated the link between environmental and molecular carcinogenesis. Subsequent studies revealed that activating mutations in the closely related Kras gene could also drive skin tumor development and progression under certain conditions. To address a head to head comparison of downstream signaling produced by each activated oncogene primary keratinocytes were isolated from the LSL-HrasG12D and LSL -KrasG12D C57BL/6J mouse models that carry conditionally expressed mutant alleles when a Lox-STOP-Lox segment is excised by Cre recombinase adenovirus treatment. Keratinocytes expressing two mutant alleles of HrasG12D (HH), only one mutant allele of HrasG12D (H), one mutant allele of KrasG12D (K) or one mutant allele of each (HK) were evaluated for differences in downstream signaling, gene expression and the ability to form squamous papillomas orthotopically in vivo.
Project description:The IRE1a-XBP1 pathway, a conserved adaptive response to the unfolded protein response, is indispensable for development of the secretory cells. It maintains endoplasmic reticulum homeostasis by enhancing protein folding and the secretory capacity of the cells. Here, we used a modified ChIP-seq protocol (ChIPmentation) to investigate the genome-wide binding events of the transcription factor XBP1 in differentiated mouse Th2 cells.
Project description:Differential gene expression profiles were observed in response to Hras in either wild-type or Ppar-beta null primary keratinocytes and differentail gene edxpression profiles by GW0742 were only found in wild-type keratinocytes. Primary keratinocytes from wild-type and Ppar-beta null mice were either mock infected or infected with an Hras encoding retrovirus and treated with or without 1 uM GW0742 for 24 hours.
Project description:The inositol-requiring enzyme-1a (IRE1a), through its key effector transcription factor X-box binding protein-1 (XBP1), regulates cell fate and malignancy in a tissue and cell-specific manner. Here, we define the transcriptional perturbations associated with IRE1a deficiency in normal murine hematopoieitic stem cell (HSC) progenitors and HSC progenitors expressing Flt3 internal tandem duplication (FLT3-ITD) allele, a myeloid leukemia oncogne. Beyond its classical role in activating genes involved in restoring cellular proteostasis during the unfolded protein response (UPR), our transcriptome analysis reveal XBP1-dependent regulation of genes involved in diverse biological processes required for HSC homeostasis and acute myeloid leukemia (AML) development.
Project description:Acute expression of E7 oncogene from HPV-16 or HPV-18 is sufficient to overcome tumor necrosis factor-alfa (TNF) cytostatic effect on primary human keratinocytes. In the present study we investigated the molecular basis of E7-induced TNF resistance through a comparative analysis of the effect of this cytokine on the proliferation and global gene expression of organotypic cultures of normal and E7(wild type or mutant)-expressing keratinocytes. In order to determine the effects of E7 expression on TNF response, we performed 3 independent experiment for each cell line. Organotypic cultures of normal and E7(wild type or mutant)-expressing keratinocytes were treated with 2 nM TNF for 72 hours, or left untreated.
Project description:The purpose of the study was to examine the role of the IRE1a-XBP1 pathway during Th2 lymphocyte activation and differentiation. In vitro Th2 cells were treated with 4μ8c, a drug that specifically inhibits IRE1a endonuclease activity, and transcriptomes were compared.
