Project description:The adult pancreas is capable of limited regeneration after injury, but has no defined stem cell population. The cell types and molecular signals that govern the production of new pancreatic tissue are not well understood. Here we show that inactivation of the SCF-type E3 ubiquitin ligase substrate recognition component Fbw7 induces pancreatic ductal cells to reprogram into β-cells. The induced β-cells resemble islet β-cells in morphology and histology, express genes essential for β-cell function, and release insulin upon glucose challenge. Thus, loss of Fbw7 appears to reawaken an endocrine developmental differentiation program in adult pancreatic ductal cells. Our study highlights the plasticity of seemingly differentiated adult cells, identifies Fbw7 as a master regulator of cell fate decisions in the pancreas, and reveals adult pancreatic duct cells as a latent multipotent cell type. We used microarray to compare adult mouse fbw7 knock out ductal cells with bonafide beta cells In order to isolate fbw7 ko, fbw7 wt ductal cells and beta cells we used adult mice with the following genotypes: MIP-GFP (beta cells are constitutively labelled with GFP), Ck19-CreERT; R26-LSL-YFP; Fbw7 +/+ (ductal cells are labelled with YFP upon tamoxifen injection) and Ck19-CreERT; R26-LSL-YFP; Fbw7 F/F mice (ductal cells are labelled with YFP upon tamoxifen injection). 30000 GFP+ cells were isolated by FACS-sorting. RNA was extracted and amplified using NuGEN kit.
Project description:During maturation of hematopoietic stem/progenitor cells (HSPCs) to fully differentiated mature B lymphocytes, developing lymphocytes may undergo malignant transformation and produce B-cell lymphomas. Emerging evidence shows that through the endothelial-hematopoietic transition, specialized endothelial cells called the hemogenic endothelium can differentiate into HSPCs. However, the contribution of genetic defects in hemogenic endothelial cells to B-cell lymphomagenesis has not yet been investigated. /
Project description:Proteomics on HCT116 cells. 3 samples wild-type, 3 samples Fbw7 KO. Subcellular fractionation to cytoplasmic and nuclear fractions. Proteins were reduced with DTT, alkylated with iodoacetamide, digested with trypsin, and labelled with TMT6-plex: 126,127,128 - wildtype; 129,130,131 - Fbw7 KO. Sample separation by high resolution isoelectric focusing at peptide level, whereafter 72 fractions were loaded onto reversed phase LC-MSMS
Project description:Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-mediated substrate degradation is antagonized by the Usp28 deubiquitinase. We now show, using knockout mice, that Usp28 preferentially deubiquitinates and stabilizes Fbw7. Monoallelic deletion of Usp28 maintains stable Fbw7 but destabilizes Fbw7 substrates. In contrast, complete knockout of Usp28 promotes Pin1-dependent autocatalytic turnover of Fbw7, accumulation of Fbw7 substrates and oncogenic transformation. Overexpression of Usp28 stabilizes both Fbw7 and its substrates and similarly enhances transformation. We propose that dual regulation of Fbw7 activity by Usp28 maintains physiological levels of Fbw7 substrates, and that both loss and overexpression of Usp28 in human cancer promote Fbw7 substrate accumulation.
Project description:Ubiquitination is a post-translational mechanism of control of diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes including Notch1, c-Myc and cyclin E. We have generated conditional Fbw7 knock-out animals and inactivated the gene in hematopoietic stem cells (HSC) and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects the HSC compartment in a cell-autonomous manner. Fbw7-/- HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7-/- HSC are unable to colonize the thymus leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E are stabilized in the bone marrow of Fbw7 deficient mice. Genome-wide transcriptome studies of Fbw7-/- HSC and hematopoietic progenitors indicate that Fbw7 controls, through the regulation of HSC cell cycle entry, the global transcriptional âsignatureâ that is associated with the quiescent, self-renewing HSC phenotype. Transcriptional consequences of inactivating Fbw7 in LKS cells. Experiment Overall Design: Four samples were analyzed: wild-type (WT) control and Fbw7-deficient (FBW7) Lin-ckit+Sca1+ (LSK) cells, as well as Lin-ckit+Sca1- myeloid progenitor (MP) cells, which served as a control for LSK-enriched/specific genes. Total bone marrow cells were pooled from three WT and three FBW7 mice before sorting LSK and MP populations.
Project description:Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-mediated substrate degradation is antagonized by the Usp28 deubiquitinase. We now show, using knockout mice, that Usp28 preferentially deubiquitinates and stabilizes Fbw7. Monoallelic deletion of Usp28 maintains stable Fbw7 but destabilizes Fbw7 substrates. In contrast, complete knockout of Usp28 promotes Pin1-dependent autocatalytic turnover of Fbw7, accumulation of Fbw7 substrates and oncogenic transformation. Overexpression of Usp28 stabilizes both Fbw7 and its substrates and similarly enhances transformation. We propose that dual regulation of Fbw7 activity by Usp28 maintains physiological levels of Fbw7 substrates, and that both loss and overexpression of Usp28 in human cancer promote Fbw7 substrate accumulation. RNAseq experiments of E13.5 murine embryonic fibroblasts (MEFs) derived from animals in which Usp28 was either deleted (-/-), wildtype (+/+) or heterozygous (+/-). In a first set of experiments immortalized MEFs of all three genotypes were analysed in biological triplicates. In a second set of experiments immortalized and Ras transformed MEFs of all three genotypes and MEFs which overexpress USP28 (+/+/+) where sequenced in duplicates.
Project description:Ubiquitination is a post-translational mechanism of control of diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes including Notch1, c-Myc and cyclin E. We have generated conditional Fbw7 knock-out animals and inactivated the gene in hematopoietic stem cells (HSC) and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects the HSC compartment in a cell-autonomous manner. Fbw7-/- HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7-/- HSC are unable to colonize the thymus leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E are stabilized in the bone marrow of Fbw7 deficient mice. Genome-wide transcriptome studies of Fbw7-/- HSC and hematopoietic progenitors indicate that Fbw7 controls, through the regulation of HSC cell cycle entry, the global transcriptional “signature” that is associated with the quiescent, self-renewing HSC phenotype. Transcriptional consequences of inactivating Fbw7 in LKS cells. Keywords: cell type comparison
Project description:Fbw7 plays a negative role in pancreatic cancer tumorigenesis and progression. To further clarify the function and mechanism that Fbw7 plays in pancreatic cancer,mRNA microarray assays were performed to identify the genes and signaling pathways that were changed upon Fbw7 overexpression.
Project description:Fbw7 is one of the most highly mutated tumor suppressor genes in human cancers. Several Fbw7 mutation types have been found in cancers (e.g. Fbw7Arg/+, other missense mutations and Fbw7-/-). Fbw7Arg/+ missense mutation is the most commonly observed mutation type, however the tumorigenic mechanisms led by Fbw7Arg/+ are as of yet poorly understood. Fbw7 targets almost thirty proteins to degradation, out of many are transcription factors. We performed an integrative study to understand global transcriptional regulation by Fbw7. We investigated the deregulation of two well-studied oncogenic Fbw7 substrates: cMyc and cJun in wild-type and Fbw7 mutant colorectal cancer cell lines and neural stem cells. Our study revealed context-specific transcriptional regulation by Fbw7.
Project description:Fbw7 plays a negative role in pancreatic cancer tumorigenesis and progression. To further clarify the function and mechanism that Fbw7 plays in pancreatic cancer,mRNA microarray assays were performed to identify the genes and signaling pathways that were changed upon Fbw7 overexpression. Fbw7 overexpressing SW1990 cells were cultured for RNA extraction and hybridization on Affymetrix mRNA microarrays. These were compared against the control,which were infected by empty control lentiviral particles.