PI3K signaling and FOXO transcription factors play opposing roles at several B cell developmental stages. We show here abundant nuclear FOXO1 expression in the proliferative compartment of the germinal center (GC), its dark zone (DZ), and PI3K activity, downregulating FOXO1, in the GC light zone (LZ), where cells are selected for further differentiation. However, here FOXO1 is expressed in c-Myc+ cells destined for DZ reentry. Upon FOXO1 ablation by genetic means or induction of PI3K activity GCs become devoid of their DZ, due at least partly to the downregulation of the chemokine receptor CXCR4. While this is known to prevent proper cyclic selection of cells expressing high-affinity antibodies, the initiation of immunoglobulin switching is essentially dependent on FOXO1 activity.
PI3 Kinase and FOXO1 Transcription Factor Activity Differentially Control B Cells in the Germinal Center Light and Dark Zones.
Specimen part
View SamplesIn Burkitt lymphoma (BL), an aggressive germinal-center (GC) derived non-Hodgkin B-cell lymphoma characterized by MYC translocations as early transforming event, the apoptotic properties of MYC must have been overcome by pro-survival signals. Whereas activation of the pro-survival factor NFkappaB is not eminent in BL, PI3K signalling, which mediates B cell receptor associated survival signals in mature B cells, might be the cooperating event. Here we prove this hypothesis by the generation of BL in mice upon concordant expression of MYC and activation of PI3K in GC B cells. Unlike existing murine BL-like models, our tumour model fully phenocopies primary human BL and reflects the complexity of the disease with regard to histological appearance, surface marker expression, and characteristic gene expression profiles. Like in human BL, tumour monoclonality indicated a multistep pathogenesis underlining MYC and PI3K as predisposing events that invariably lead to GC-derived BL formation. In accordance, copy number alteration analysis revealed genomic regions involved in BL pathogenesis.
Synergy between PI3K signaling and MYC in Burkitt lymphomagenesis.
Specimen part
View SamplesCritically short telomeres activate p53-mediated apoptosis, resulting in organ failure and causing malignant transformation. Mutations in genes responsible for telomere maintenance are linked to a number of specific human diseases. We derived induced pluripotent stem cells (iPSCs) from patients with mutations in the TERT and TERC telomerase genes. Telomerase-mutant iPSCs elongated telomeres, but at a lower rate than healthy iPSCs, and the magnitude of the elongation deficit correlated with the specific mutations impact on telomerase activity. However, elongation significantly varied among iPSC clones harboring the same mutation, and was affected by genetic and environmental factors. iPSCs cultured in hypoxia showed increased telomere length. Potential influence of residual expression of reprogramming factors on telomerase regulation and telomere length was ruled out by excising the transgenes after successful reprogramming. Evidence for telomerase-independent telomere elongation was not observed in these cells. We demonstrate that telomerase is required for telomere elongation in iPSCs and uncover heterogeneity in telomere maintenance even between clones derived from individual patients or siblings with the same mutation, indicating that telomere phenotype may be influenced by acquired and environmental agents. Our data underscore the necessity of studying multiple clones when using iPSCs to model disease. The exon array were done to validate the pluripotent phenotype of the derived normal and telomerase mutant iPSC and to potentially identify differentially expressed genes in mutant iPSC.
Defective telomere elongation and hematopoiesis from telomerase-mutant aplastic anemia iPSCs.
Specimen part, Cell line
View SamplesGlobal transcriptome analysis showed that human lymphatic endothelial cells (LECs) grown on a soft matrix exhibit increased GATA2 expression, concomitant with a GATA2-dependent upregulation of genes involved in cell migration and lymphangiogenesis, including the key lymphangiogenic growth factor receptor VEGFR3.
Matrix stiffness controls lymphatic vessel formation through regulation of a GATA2-dependent transcriptional program.
Specimen part
View SamplesThe occurrence of clonal perturbations and leukemia in patients transplanted with retrovirally-transduced autologous hematopoietic stem and progenitor cells (HSPCs) has stimulated extensive investigation, demonstrating that proviral insertions perturb adjacent proto-oncogene expression. Although enhancer-deleted lentiviruses are less likely to result in insertional oncogenesis, there is evidence that they may perturb transcript splicing, and one patient with a benign clonal expansion of lentivirally-transduced HPSC has been reported. The rhesus macaque model provides an opportunity for informative long-term analysis to ask whether transduction impacts on long-term HSPC properties. We utilized two techniques to examine whether lentivirally-transduced HSPCs from eight rhesus macaques transplanted 1-13.5 years previously are perturbed at a population level, comparing telomere length as a measure of replicative history and gene expression profile of vector positive versus vector negative cells. There were no differences in telomere lengths between sorted GFP+ and GFP- blood cells, suggesting that lentiviral transduction did not globally disrupt replicative patterns. Bone marrow GFP+ and GFP- CD34+ cells showed no differences in gene expression using unsupervised and principal component analysis. These studies did not uncover any global long-term perturbation of proliferation, differentiation, or other important functional parameters of transduced HSPCs in the rhesus macaque model.
No impact of lentiviral transduction on hematopoietic stem/progenitor cell telomere length or gene expression in the rhesus macaque model.
Specimen part
View SamplesWe studied the effects of acute activation of the melanoma oncogene RAC1 P29S using a tamoxifen-inducible ER-fusion protein system in mouse melanocytes Overall design: An ER-RAC1 P29S fusion protein was stably expressed in the spontaneously immortalized mouse melanocyte cell line melan-a. The fusion protein was activated by treatment with 500 nM 4OH-tamoxifen. RNA was isolated and sequenced at 0 h, 4 h and 40 h post-treatment. The gene expression profiles at 4 h and 40 h were compared to the 0 h time-point. To control for effects induced by 4OH-tamoxifen independent from ER-RAC1 P29S, we performed the same experiment in melan-a cells transduced with an empty vector.
RAC1<sup>P29S</sup> Induces a Mesenchymal Phenotypic Switch via Serum Response Factor to Promote Melanoma Development and Therapy Resistance.
Subject
View SamplesWe studied the effects of endogenous expression of the melanoma oncogene RAC1 P29S in BRAF V600E;PTEN hemizygous mouse melanomas. Overall design: Transgenic mice with a conditional knock-in of the P29S mutation in the endogenous Rac1 locus were generated and crossed onto C57BL/6J, Tyr-CreER;BrafCA/wt;Ptenfl/wt mice. Melanomas were induced by topical 4OH-tamoxifen. We compared the gene expression profile in whole tumour lysates from Tyr-CreER+/-;Ptenfl/wt;BrafCA/wt;Rac1LSL-P29S/wt mice versus Tyr-CreER+/-;Ptenfl/wt;BrafCA/wt;Rac1wt/wt mice (n = 6 tumours from 5-6 animals per group).
RAC1<sup>P29S</sup> Induces a Mesenchymal Phenotypic Switch via Serum Response Factor to Promote Melanoma Development and Therapy Resistance.
Cell line, Subject
View Samplesp63 mutations have been associated with several human hereditary disorders characterized by ectodermal dysplasia such as EEC syndrome, ADULT syndrome and AEC syndrome . The location and functional effects of the mutations that underlie these syndromes reveal a striking genotype-phenotype correlation. Unlike EEC and ADULT that result from missense mutations in the DNA-binding domain of p63, AEC is solely caused by missense mutations in the SAM domain of p63. We report a study on the TAp63a isoform, the first to be expressed during development of the embryonic epithelia, and on its naturally occurring Q540L mutant derived from an AEC patient. To assess the effects of the Q540L mutation, we generated stable cell lines expressing TAp63a wt, DeltaNp63 alpha or the TAp63 alpha-Q540L mutant protein and used them to systematically compare the cell growth regulatory activity of the mutant and wt p63 proteins and to generate, by microarray analysis, a comprehensive profile of differential gene expression. We found that the Q540L substitution impairs the transcriptional activity of TAp63a and causes misregulation of genes involved in the control of cell growth and epidermal differentiation.
The Hay Wells syndrome-derived TAp63alphaQ540L mutant has impaired transcriptional and cell growth regulatory activity.
No sample metadata fields
View SamplesHepatocellular carcinoma (HCC) is ranked second in cancer-associated deaths worldwide. Most cases of HCC are secondary to either a viral hepatitis infection (hepatitis B or C) or cirrhosis (alcoholism being the most common cause of hepatic cirrhosis). It is a complex and heterogeneous tumor due to activation of multiple cellular pathways and molecular alterations.
Exome sequencing of hepatocellular carcinomas identifies new mutational signatures and potential therapeutic targets.
Sex, Age, Specimen part, Disease, Disease stage
View SamplesTranscriptome study of 2 Saccharomyces cerevisiae W303 derivatives, one carrying GFP (control) and one carrying aSyn-GFP
Different 8-hydroxyquinolines protect models of TDP-43 protein, α-synuclein, and polyglutamine proteotoxicity through distinct mechanisms.
Specimen part, Disease, Cell line
View Samples