Stress induces undifferentiated stem cells to differentiate in a way that looks like normal differentiation
Hyperosmolar stress induces global mRNA responses in placental trophoblast stem cells that emulate early post-implantation differentiation.
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View SamplesDespite advances in investigating functional aspects of osteoblast (OB) differentiation, especially studies on how bone proteins are deposited and mineralized, there has been little research on the intracellular trafficking of bone proteins during OB differentiation. Collagen synthesis and secretion is markedly upregulated upon Ascorbic Acid (AA) stimulation. Understanding the mechanism by which collagen is mobilized in specialized OB cells is important for both basic cell biology and diseases involving defects in bone secretion and deposition. RabGTPases are major regulators on protein trafficking throughout the cell. In this study, we identified the Rab GTPases that are upregulated during 5-day AA differentiation of OBs using microarray analysis, namely Rab1, Rab3d and Rab27b.
Rab GTPase mediated procollagen trafficking in ascorbic acid stimulated osteoblasts.
Specimen part, Cell line
View SamplesNormal erythropoiesis requires a critical balance between proapoptotic and antipaoptotic pathways. Bcl-xl, an antiapoptotic protein is induced at end-stages of differentiation of erythroid precursors in response to erythropoietin. The details of the proapoptotic pathway and the critical proapoptotic proteins inhibited by Bcl-xl in erythropoiesis are not well understood. We employed gene targeting to ablate Nix, a proapoptotic BH3-domain only Bcl2 family protein, which is known to be transcriptionally induced during erythropoiesis. Nix null mice exhibited reticulocytosis and thrombocytosis in the peripheral blood; and profound splenomegaly with erythroblastosis in the spleen and bone marrow despite normal erythropoietin levels and blood oxygen tension. In vivo apoptosis was diminished in erythroblast precursors from Nix null spleens. To define the molecular consequences of Nix ablation on apoptosis and erythropoiesis, we conducted a detailed comparative analysis of gene expression in spleens from 8 week old Nix null mice and wild type controls. Of 45,101 genes analyzed, 514 were significantly upregulated and 386 down-regulated in Nix-/- splenocytes. Functional cluster analysis delineated the ten most highly regulated gene sets, revealing increased levels of cell cycle and erythroid genes, with decreased levels of cell death and B-cell genes.
Unrestrained erythroblast development in Nix-/- mice reveals a mechanism for apoptotic modulation of erythropoiesis.
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View SamplesThe MAQC-II Project: A comprehensive study of common practices for the development and validation of microarray-based predictive models
Effect of training-sample size and classification difficulty on the accuracy of genomic predictors.
Sex, Age, Specimen part, Race, Compound
View SamplesThe Hamner data set (endpoint A) was provided by The Hamner Institutes for Health Sciences (Research Triangle Park, NC, USA). The study objective was to apply microarray gene expression data from the lung of female B6C3F1 mice exposed to a 13-week treatment of chemicals to predict increased lung tumor incidence in the 2-year rodent cancer bioassays of the National Toxicology Program. If successful, the results may form the basis of a more efficient and economical approach for evaluating the carcinogenic activity of chemicals. Microarray analysis was performed using Affymetrix Mouse Genome 430 2.0 arrays on three to four mice per treatment group, and a total of 70 mice were analyzed and used as the MAQC-II's training set (GEO Series GSE6116). Additional data from another set of 88 mice were collected later and provided as the MAQC-II's external validation set (this Series). The training dataset had already been deposited in GEO by its provider and its accession number is GSE6116.
Effect of training-sample size and classification difficulty on the accuracy of genomic predictors.
Specimen part, Compound
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