Fetal and neonatal beta cells have poor glucose-induced insulin secretion and only gain robust glucose responsiveness several weeks after birth. This unresponsiveness may be due to a generalized immaturity of the metabolic pathways normally found in beta cells.
Rat neonatal beta cells lack the specialised metabolic phenotype of mature beta cells.
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View SamplesOur hypothesis was that at any given point in time, islets will contain differing populations of beta cells at different stages of their lifecycle, with further changes occurring with metabolic stress and aging. We examined subpopulations of beta cells isolated from MIP-GFP mice on the basis of their insulin transcriptional activity and in their expression of p16Ink4a. In addition, using aging C57Bl/6 mice as a model, markers of beta cell aging were identified and validated: Igf1r and Cd99 expression increased with age, whereas Kcnq5 was decreased with age. These markers were correlated with an age-related decline in function. The functional aging of beta cells was accelerated by S961, an antagonist to the insulin receptor, which induced insulin resistance. Particularly surprising was the finding of marked islet heterogeneity as demonstrated with the marked staining differences of the markers: Igf1r, Cd99 and Kcnq5. These novel findings about beta cell and islet heterogeneity, and how they change with age, open up an entirely new set of questions that must be addressed about the pathogenesis of type 2 diabetes. The present study has identified new markers of aging in beta cells and found that the expression of these and other markers can be increased by insulin resistance. This provides insight into how insulin resistance might accelerate the death of beta cells. In addition, striking heterogeneity among islets was found, which opens up new ways to think about islet biology and the pathogenesis of T2D.
β Cell Aging Markers Have Heterogeneous Distribution and Are Induced by Insulin Resistance.
Age, Specimen part
View SamplesThe functioning of a specific tissue depends on the expression pattern of the different genes. We used microarrays to compare gene expression across different murine tissues, to get a better understanding in the expression pattern and functioning of the different tissues. With this analysis, we were not only able to identify genes that were specifically expressed in a spicific tissue but, as important, we also identified genes that were specifically repressed in a tissue, compared to al the other analysed tissues.
Tissue-specific disallowance of housekeeping genes: the other face of cell differentiation.
Sex, Specimen part
View SamplesWe used Affymetrix Gene Arrays (1.0 ST) to compare gene expression across different murine tissues.
Tissue-specific disallowance of housekeeping genes: the other face of cell differentiation.
Specimen part
View SamplesThe unique metabolic profile of most cancers (aerobic glycolysis) might confer apoptosis-resistance and be therapeutically targeted. Compared to normal cells, several human cancers have high mitochondrial membrane potential and low expression of the K+ channel Kv1.5, both contributing to apoptosis-resistance. Dichloroacetate (DCA), an inhibitor of the mitochondrial pyruvate dehydrogenase kinase (PDK), shifts metabolism from glycolysis to glucose oxidation, decreases mitochondrial membrane potential, increases mitochondrial-H2O2 and activates Kv channels in all cancer, but not normal cells; DCA upregulates Kv1.5 by an NFAT1-dependent mechanism. DCA induces apoptosis, decreases proliferation and tumor growth in vitro and in vivo, without apparent toxicity. Molecular inhibition of PDK2 by siRNA mimics DCA. The mitochondria-NFAT-Kv axis and PDK are important therapeutic targets in cancer; the orally available DCA is a novel selective anticancer agent.
A mitochondria-K+ channel axis is suppressed in cancer and its normalization promotes apoptosis and inhibits cancer growth.
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View SamplesGene expression profiles from ALDH high cells sorted from expanded adult human pancreatic organoids are more similar to fetal pancreatic tissue and ALDH high cells sorted from expanded fetal human pancreatic organoids than to adult human islets or adult islet-depleted exocrine tissue. Overall design: RNA was isolated from ALDHhi cells sorted from organoids after 7 days expansion derived from human adult pancreatic tissue, ALDHhi cells sorted from organoids after 7 days expansion derived from human fetal pancreatic tissue, primary fetal pancreatic tissue, adult human islets from different donors and adult exocrine (islet-depleted) pancreatic tissue from different donors.
Expansion of Adult Human Pancreatic Tissue Yields Organoids Harboring Progenitor Cells with Endocrine Differentiation Potential.
Specimen part, Subject
View SamplesExposure to vanadium pentoxide (V2O5) is a cause of occupational bronchitis. We evaluated gene expression profiles in cultured human lung fibroblasts exposed to V2O5 in vitro in order to identify candidate genes that could play a role in airway remodeling associated with V2O5-induced bronchitis. Gene expression was measured at various time points over a 24 hr period using the Affymetrix Human Genome U133A 2.0 Array. Expression data were preprocessed using RMA with a log2 transformation. Statistical analysis was performed in R using the affylmGUI package using a linear model with contrasts between untreated control and V2O5-exposed fibroblasts. Genes identified as statistically significant were filtered by selecting only those genes that exhibited a > 2-fold change. Quantitative real-time RT-PCR was utilized to confirm expression of selected genes. More than 2000 genes were significantly changed in response to V2O5 over the time course of our experiment. Genes altered by V2O5 were involved in biologic processes related to cell growth and differentiation, oxidative stress responses, immune regulation, and interferon signaling and apoptosis. In particular, V2O5 induced genes that encode growth factors involved in epithelial repair (HB-EGF) or angiogenesis (VEGF), peroxide generating enzymes (SOD2), pro-inflammatory enzymes (PGHS2), while suppressing genes involved in growth arrest (GAS1, STAT-1) and cell cycle inhibition (CDKN1B). Our study also identified a variety of novel genes that could be used as biomarkers of V2O5-induced bronchitis or could serve as candidate genes for disease progression.
Genomic analysis of human lung fibroblasts exposed to vanadium pentoxide to identify candidate genes for occupational bronchitis.
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View SamplesThe present research is devoted to the identification of gene(s) severely affected by EMD mutations, leading to striated muscle laminopathies and more specifically the cardiomyopathy. For this purpose, we developped a large-scale gene expression approach on heart and skeletal tissues from Emd KO mouse model.
Activation of MAPK in hearts of EMD null mice: similarities between mouse models of X-linked and autosomal dominant Emery Dreifuss muscular dystrophy.
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View SamplesOvarian follicular granulosa cells surround and nurture oocytes, and produce sex steroid hormones. It is believed that during development the ovarian surface epithelial cells invaginate into the ovary and develop into granulosa cells when associating with oogonia to form follicles. Using bovine fetal ovaries (n = 53) we identified a novel cell type, termed GREL for Gonadal Ridge Epithelial-Like. Using 25 markers for GREL and other cells we conducted immunohistochemistry and electron microscopy and chronologically tracked all somatic cell types during development. Before 70 days of gestation the gonadal ridge/ovarian primordium is formed by proliferation of GREL cells at the surface epithelium of the mesonephros. Primordial germ cells (PGCs) migrate into the ovarian primordium. After 70 days, stroma from the underlying mesonephros begins to penetrate the primordium, partitioning the developing ovary into irregularly-shaped ovigerous cords composed of GREL cells and PGCs/oogonia. Importantly we identified that the cords are separated from the stroma by a basal lamina. Around 130 days of gestation as the stroma expands laterally below the GREL cells on the surface thus establishing a sub-epithelial basal lamina and an epithelial-stromal interface, and it is at this stage that a mature surface epithelium develops from the GREL cells. The stroma continues to partition the ovigerous cords into smaller groups of cells eventually forming follicles containing an oogonium/oocyte surrounded by GREL cells, which become granulosa cells. Thus in contrast to the prevailing theory, the ovarian surface epithelial cells do not invaginate into the ovary to form the granulosa cells of follicles.
A new model of development of the mammalian ovary and follicles.
Specimen part
View SamplesDisruption of peripheral circadian rhyme pathways dominantly leads to metabolic disorders. Studies on circadian rhythm proteins in the heart indicated a role for Clock or Per2 in cardiac metabolism. In fact, Per2-/- mice have larger infarct sizes with a deficient lactate production during myocardial ischemia. To test the hypothesis that cardiac Per2 represents an important regulator of cardiac metabolism during myocardial ischemia, we performed lactate measurements during reperfusion in Per1-/-, Per2-/- or wildtype mice followed by gene array studies using various ischemia-reperfusion protocols comparing wildtype and Per2-/- mice. Lactate measurements in whole blood confirmed a dominant role of Per2 for lactate production during myocardial ischemia. Surprisingly, high-throughput gene array analysis of eight different conditions on one 24-microarray plate revealed dominantly lipid metabolism as differentially regulated pathway in wildtype mice when compared to Per2-/-. In all treatment groups, the enzyme enoyl-CoA hydratase, which is essential in fatty acid beta-oxidation, was regulated in wildtype animals only. Studies using nuclear magnet resonance imaging (NMRI) confirmed altered fatty acid populations with higher mono-unsaturated fatty acid levels in hearts from Per2-/- mice. Unexpectedly, studies on gene regulation during reperfusion revealed solely pro inflammatory genes as differentially regulated 'Per2-genes'. Subsequent studies on inflammatory markers showed increasing IL6 or TNFa levels during reperfusion in Per2-/- mice. In summary, these studies reveal a novel role of cardiac Per2 for fatty acid metabolism or inflammation during myocardial ischemia and reperfusion.
Cardiac Per2 functions as novel link between fatty acid metabolism and myocardial inflammation during ischemia and reperfusion injury of the heart.
Sex, Specimen part
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