The specific deletion of Rb gene in epidermis leads to altered proliferation and differentiation, but not to the development of spontaneous tumors. Our previous data have demonstrated the existence of a functional compensation of Rb loss by Rbl1 (p107) in as the phenotypic differences with respect to controls are intensified. However, the possible evolution of this aggravated phenotype, in particular in relationship with tumorigenesis, has not been evaluated due to the premature death of the double deficient mice. We have now investigated whether p107 can also act as a tumor suppressor in pRb-deficient epidermis using different experimental approaches. We found spontaneous tumor development in doubly-deficient skin grafts. Moreover, Rb-deficient keratinocytes are susceptible to Ha-ras-induced transformation, and this susceptibility is enhanced by p107 loss. Further functional analyses, including microarray gene expression profiling, indicated that the loss of p107, in the absence of pRb, produces the reduction of p53-dependent pro-apoptotic signals. Overall, our data demonstrate that p107 behaves as a tumor suppressor in epidermis in the absence of pRb and suggest novel tumor-suppressive roles for p107 in the context of functional p53 and activated Ras
p107 acts as a tumor suppressor in pRb-deficient epidermis.
Specimen part
View SamplesLymphatic endothelial cells were grown under normoxia, hypoxia (1% 0xygen) and conditioned medio from NSLCN growth under normoxia or hypoxia. Gene expression was measured and comparition between samples performed
Hypoxia alters the adhesive properties of lymphatic endothelial cells. A transcriptional and functional study.
No sample metadata fields
View SamplesAim: To determine the role of NOTCH during the response-to-injury and subsequent chronic inflammatory process of the arterial wall underlying atherosclerosis. Methods and results: We have generated an endothelial-specific RBPJK depleted mice using the Cdh5 cadherin promoter (ApoE-/-;RBPJflox/flox;Cdh5- CreERT). Endothelial-specific deletion of the Notch effector RBPJK or systemic deletion of the Notch1 receptor in athero-susceptible ApoE-/- mice fed a HC diet for 6 weeks resulted in reduced atherosclerosis in the aortic arch and sinus. Intravital microscopy revealed decreased leukocyte rolling on the endothelium of ApoE-/-;RBPJflox/flox;Cdh5- CreERT, that correlated with the lesser presence of leukocyts and macrophages in the vascular wall. Consistent with this, transcriptome analysis revealed that proinflammatory and endothelial activation pathways were downregulated in atherosclerotic tissue of RBPJk-mutant mice.. Jagged1 signaling upregulation in endothelial cells promotes the physical interaction and nuclear translocation of the intracellular domain of the Notch1 receptor (N1ICD) with NF-kB,. This N1ICD and NF-kB interaction is required for reciprocal transactivation of target genes including vascular cell adhesion molecule-1 (Vcam1). Conclusions: Notch signaling pathway inactivation decreases leukocyte rolling, thereby preventing endothelial dysfunction and vascular inflammation. Thus attenuating Notch signaling may constitute a useful therapeutic strategy for atherosclerosis. Key words: atherosclerosis, endothelium, signaling pathways, Notch, NF-kB, transcriptional regulation Overall design: RNA was isolated from the aortic arches of three ApoE-/-;RBPJflox/flox and three ApoE-/-; RBPJflox/flox;Cdh5-CreERTmice
Endothelial Jag1-RBPJ signalling promotes inflammatory leucocyte recruitment and atherosclerosis.
No sample metadata fields
View SamplesCxcr7-/- mice die a few hours after birth. All of them display semilunar valves abnormalities, including bicuspid aortic or pulmonary valves. Those defects only become obvious before birth.
Disrupted cardiac development but normal hematopoiesis in mice deficient in the second CXCL12/SDF-1 receptor, CXCR7.
No sample metadata fields
View SamplesWe have characterized a mutation affecting the Arabidopsis EARLY IN SHORT DAYS 7 (ESD7) gene encoding the catalytic subunit of the DNA polymerase epsilon (e), AtPOL2A. esd7-1 mutations causes early flowering independently of photoperiod, shortened inflorescence internodes and altered leaf and root development. esd7-1 was a hypomorphic allele whereas KO alleles displayed an embryo-lethal phenotype. The SAM and the RAM in the esd7-1 seedlings were found to exhibit an altered disposition that might correlate with the abnormal expression pattern of SAM and RAM marker genes. esd7-1 showed higher sensitivity to DNA damaging reagents than wild type plants and altered expression of genes involved in DNA repair mechanisms by homologous recombination. Moreover, esd7 early flowering phenotype requires functional FT and SOC1 proteins and might be also related to the mis-regulation of AG and AG-like gene expression found in esd7. Loci involved in the modulation of the chromatin structural dynamics, such as TFL2 and EBS, which negatively regulate FT expression, were found to interact genetically with ESD7, and the carboxy terminus of ESD7 interacted with TFL2 in vitro. Besides, fasciata2 (fas2) mutations suppressed esd7 early flowering phenotype and INCURVATA 2 (ICU2) was found to be epistatic to ESD7. Discrete regions of the chromatin of FT and AG loci were enriched in activating epigenetic marks in the esd7-1 mutant. We concluded that ESD7 might be participating in processes involved in chromatin-mediated cellular memory.
EARLY IN SHORT DAYS 7 (ESD7) encodes the catalytic subunit of DNA polymerase epsilon and is required for flowering repression through a mechanism involving epigenetic gene silencing.
Specimen part
View SamplesBladder cancer (BC) is a highly prevalent human disease in which Rb pathway inactivation and epigenetic alterations are common events. However, the connection between these two processes is still poorly understood. Here we show that the in vivo inactivation of all Rb family genes in the mouse urothelium is sufficient to initiate BC development. The characterization of the mouse tumors revealed multiple molecular features of human BC, including the activation of E2F transcription factor and subsequent Ezh2 expression, and the activation of several signaling pathways previously identified as highly relevant in urothelial tumors. Whole transcriptional characterizations of the mouse bladder tumors revealed a significant overlap with human BC samples, and a predominant role for Ezh2 in the downregulation of gene expression programs. Importantly, we determined that in human superficial BC patients, the increased tumor recurrence and progression in these recurrences is associated with increased E2F and Ezh2 expression and Ezh2-mediated gene expression repression. Collectively, our studies provide a genetically defined model for human high-grade superficial BC and demonstrate the existence of an Rb-E2F-Ezh2 axis in bladder whose disruption can promote tumor development.
In vivo disruption of an Rb-E2F-Ezh2 signaling loop causes bladder cancer.
Specimen part, Disease, Treatment
View SamplesUpon antigen recognition within peripheral lymphoid organs, B cells interact with T cells and other immune cells to transiently form morphological structures called germinal centers (GCs), which are required for B cells clonal expansion, immunoglobulin class switching, and affinity maturation. This process, known as the GC response, is an energetically demanding process that requires metabolic reprogramming of B cells. Here, we showed that the Ras-related guanosine triphosphate hydrolase (GTPase) R-Ras2 (also known as TC21) plays an essential, nonredundant, and B cellintrinsic role in the GC response. Both the conversion of B cells into GC B cells and their expansion were impaired in mice lacking R-Ras2, but not in those lacking a highly-related R-Ras subfamily member or both the classic H-Ras and N-Ras GTPases. In the absence of R-Ras2, activated B cells did not increase oxidative phosphorylation or aerobic glycolysis. We showed that R-Ras2 was an effector of both the B cell receptor (BCR) and CD40 and that, in its absence, B cells exhibited impaired activation of the PI3K-Akt-mTORC1 pathway, reduced mitochondrial DNA replication, and decreased expression of genes involved in glucose metabolism. Because most human B cell lymphomas originate from GC B cells or B cells that have undergone the GC response, our data suggests that R-Ras2 may also regulate metabolism in B cell malignancies.
R-Ras2 is required for germinal center formation to aid B cells during energetically demanding processes.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Metabolomic Identification of Subtypes of Nonalcoholic Steatohepatitis.
Age, Specimen part, Treatment
View SamplesMethionine adenosyltransferase (MAT) enzymes generate SAMe (S-adenosylmethionine), the main biological methyl donor. There are two MAT encoding genes in mammals (Mat1a and Mat2a), which show different activities and cellular distribution. Mat1a encodes the enzyme mainly expressed in normal liver. Mat1a ablation in mice results in the spontaneous development of non-alcoholic steatohepatitis (NASH). We observed that SAMe depletion in Mat1a KO mice had three main effects on hepatic lipid metabolism: 1) impaired TG (triglyceride) export via VLDL; 2) impaired mitochondrial FA (fatty acid) oxidation (as evidenced by membrane depolarization, downregulation of Phb1 (prohibitin 1, a mitochondrial chaperone protein) and Mcj/Dnajc15 (endogenous mitochondrial repressor of respiratory chain), and accumulation of long-chain acylcarnitines); and 3) increased FA uptake. The convergence of these three factors induced TG accumulation in LD (lipid droplets). LD expansion confronts hepatocytes with a high demand of PC (phosphatidylcholine) molecules to cover the LD surface since other phospholipids, such as PE (phosphatidylethanolamine), cannot stabilize LD and prevent coalescence. In Mat1a KO this situation is aggravated, since SAMe-dependent PC synthesis via PE methylation is decreased, the PC/PE ratio reduced and mitochondrial FA oxidation impaired. To put a brake to this drain of PC molecules to LD, FA are rerouted in Mat1a KO mice liver to other catabolic (endoplasmic reticulum and peroxisome oxidation) and biosynthetic (ceramides synthesis) pathways, causing oxidative stress, inflammation and fibrosis. SAMe treatment for two months in 8-9 month old Mat1a KO mice ameliorated mitochondrial dysfunction (reduces membrane depolarization, improves Phb1 and Mcj expression, and increases SAMe transport to mitochondria) improving FA oxidation efficiency (FA and acylcarnitine levels decrease), which results in a drastic reduction in TG accumulation. SAMe treatment in Mat1a KO mice resulted in more PC available for proper membrane function, improving liver lipid homeostasis, histology (H&E, Sudan red, Sirius red) and liver injury (ALT, AST).
Metabolomic Identification of Subtypes of Nonalcoholic Steatohepatitis.
Age, Specimen part
View SamplesThe rapid transit from hypoxia to normoxia in the lung that follows the first breath in newborn mice coincides with alveolar macrophage (AM) differentiation. However, whether sensing of oxygen affects AM maturation and function has not been previously explored. We have generated mice whose AMs show a deficient ability to sense oxygen after birth by deleting Vhl, a negative regulator of HIF transcription factors, in the CD11c compartment (CD11c?Vhl mice). VHL-deficient AMs show an immature-like phenotype and an impaired self-renewal capacity in vivo that persists upon culture ex vivo. VHL-deficient phenotype is intrinsic in AMs derived from monocyte precursors in mixed bone marrow chimeras. Moreover, unlike control Vhlfl/fl, AMs from CD11c?Vhl mice do not revert pulmonary alveolar proteinosis when transplanted into Csf2rb-/- mice, demonstrating that VHL contributes to AM-mediated surfactant clearance. Thus, our results suggest that optimal AM terminal differentiation, self-renewal, and homeostatic function requires their oxygen sensing capacity. Overall design: BAL AMs were pooled from 5-7 age and sex-matched mice per genotype and further purified by positive selection with anti-CD11c-microbeads (Miltenyi Biotec), following manufacturer's instructions. Cell lysis was performed with buffer RLT (Qiagen), containing 10µ/ml ß-mercaptoethanol and RNA was isolated with RNeasy Plus Mini Kit (Qiagen). RNA concentration and integrity were determined with an Agilent 2100 Bioanalyzer (Caliper Life Science). Samples with RNA integrity values > 8 were further processed. A total of 3 pools per genotype were used for RNA Seq.
Von Hippel-Lindau Protein Is Required for Optimal Alveolar Macrophage Terminal Differentiation, Self-Renewal, and Function.
Treatment, Subject
View Samples