Bone marrow hematopoietic stem cells (HSCs) are crucial to maintain lifelong production of all blood cells. Although HSCs divide infrequently, it is thought that the entire HSC pool turns over every few weeks, suggesting that HSCs regularly enter and exit cell cycle. Here, we combine flow cytometry with label-retaining assays (BrdU and histone H2B-GFP) to identify a population of dormant mouse HSCs (d-HSCs) within the lin(-)Sca1+cKit+CD150+CD48(-)CD34(-) population. Computational modeling suggests that d-HSCs divide about every 145 days, or five times per lifetime. d-HSCs harbor the vast majority of multilineage long-term self-renewal activity. While they form a silent reservoir of the most potent HSCs during homeostasis, they are efficiently activated to self-renew in response to bone marrow injury or G-CSF stimulation. After re-establishment of homeostasis, activated HSCs return to dormancy, suggesting that HSCs are not stochastically entering the cell cycle but reversibly switch from dormancy to self-renewal under conditions of hematopoietic stress
Hematopoietic stem cells reversibly switch from dormancy to self-renewal during homeostasis and repair.
Specimen part, Time
View Samplesexpression analysis from a genetically engineered mouse model of osteosarcoma
Conditional mouse osteosarcoma, dependent on p53 loss and potentiated by loss of Rb, mimics the human disease.
No sample metadata fields
View SamplesPreimplantation Genetic Testing (PGT), which encompasses both Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS), is a form of prenatal screening done on embryos conceived through assisted reproduction techniques (ART) prior to the initiation of pregnancy to ensure that only select embryos are used for transfer. PGT is typically performed on 8-cell embryos derived from either in vitro fertilization or intracytoplasmic sperm injection (ICSI) followed by extended culture. PGT requires a highly invasive embryo biopsy procedure that involves 1) incubating embryos in divalent-cation-deficient medium to disrupt cell adhesion, 2) breaching the protective zona pellucida with acid Tyrodes, laser drilling, or mechanical force and 3) aspirating one or two blastomeres. In this study we developed a mouse model of the embryo biopsy procedure inherent to PGT to determine the effect of various aspects of the procedure (incubation in Ca2+/Mg2+-free medium (CMF), acid Tyrodes treatment, blastomere aspiration), performed individually or in combination, on global patterns of gene expression in the resulting blastocysts.
The effect of blastomere biopsy on preimplantation mouse embryo development and global gene expression.
Sex
View SamplesSerum response factor (SRF) is a transcription factor that binds to the serum response element (SRE) of genes that are expressed in response to mitogens. SRF plays essential roles in muscle and nervous system development; however, little is known about the role of SRF during liver growth and function. To examine the function of SRF in the liver, we generated mice in which the Srf gene was specifically disrupted in hepatocytes. The survival of mice lacking hepatic SRF activity was lower than that of control mice; moreover, surviving mutant mice were smaller and had lower blood glucose and triglyceride levels compared with control mice. Srf-deficient livers were also smaller than control livers, hepatocyte morphology was abnormal, and liver-cell proliferation and viability was compromised. Gene array and quantitative RT-PCR analysis of SRF depleted livers revealed a reduction in mRNAs encoding components of the growth hormone/IGF1 pathway, cyclins, several metabolic regulators, and cytochrome p450 enzymes. Conclusion: SRF is essential for hepatocyte proliferation and survival, liver function, and control of postnatal body growth by regulating hepatocyte gene expression.
Hepatocyte expression of serum response factor is essential for liver function, hepatocyte proliferation and survival, and postnatal body growth in mice.
No sample metadata fields
View SamplesBackground and Aims: Although the zinc finger transcription factor GATA4 has been implicated in regulating jejunal gene expression, the contribution of GATA4 in controlling jejunal physiology has not been addressed. Methods: We generated mice in which the Gata4 gene was specifically deleted in the small intestinal epithelium. Measurements of plasma cholesterol and phospholipids, intestinal absorption of dietary fat and cholesterol, and gene expression were performed on these animals. Results: Mice lacking GATA4 in the intestine displayed a dramatic block in their ability to absorb cholesterol and dietary fat. Comparison of the global gene expression profiles of control jejunum, control ileum, and GATA4 null jejunum by gene array analysis demonstrated that GATA4 null jejunum lost expression of 53% of the jejunal-specific gene set and gained expression of 47% of the set of genes unique to the ileum. These alterations in gene expression included a decrease in mRNAs encoding lipid and cholesterol transporters as well as an increase in mRNAs encoding proteins involved in bile acid absorption. Conclusion: Our data demonstrate that GATA4 is essential for jejunal function including fat and cholesterol absorption and confirm that GATA4 plays a pivotal role in determining jejunal versus ileal identity.
GATA4 is essential for jejunal function in mice.
No sample metadata fields
View SamplesTo study the role of hepatic nuclear factor alpha (HNF4a in hepatogenesis, we used loxP-Cre technology to eliminate it from developing mouse livers.
Hepatocyte nuclear factor 4alpha orchestrates expression of cell adhesion proteins during the epithelial transformation of the developing liver.
Specimen part
View SamplesTo model the potential diabetogenic effects of higher level of HSD11B1 in b-cells of the pancreas in vivo, we created a transgenic model overexpressing HSD11B1 under the mouse insulin I promoter (MIP-HSD1) in diabetes-prone C57Bl/KsJ mice. KsJ wild type and MIP-HSD1 heterozygous mice have been high fat fed for 12 weeks. Pancreata have been perfused with collagenase and islets isolated by hand picking. Isolated islets (around 500) coming from at least 3 mice (around 200/mice) have been directly lysed in Trizol. Total RNA have been extracted by Trizol plus RNA Purification Kit (invitrogen).
Optimal elevation of β-cell 11β-hydroxysteroid dehydrogenase type 1 is a compensatory mechanism that prevents high-fat diet-induced β-cell failure.
Specimen part
View Samples5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a tumor vascular disrupting agent, is shown here to have substantial activity as a single agent against human A375 melanoma xenografts in nude mice (94 % hemorrhagic necrosis after 24 h, and 26 days growth delay following single dose at 25 mg/kg). CD45+ cells in tumor tissue increased 5-fold over the first 3 days after treatment, which was due largely to an influx of CD11b+ Ly6G+ neutrophils. Using murine and human multiplex cytokine assays to dissect the cytokines produced by host stromal cells or by the melanoma cells, it was shown that both the stromal cells and the A375 melanoma cells produced cytokines capable of attracting neutrophils into the tumor. The same xenografts were also analyzed using human and mouse Affymetrix microarrays to separately identify tumor cell-specific (human) and stromal cell-specific (mouse) gene expression changes. DMXAA induced numerous stromal cytokine mRNAs, including IP-10, IL-6, MIP-1/, MIP-2, KC, RANTES, MIG, MCP-1 and IL-1, many of which were also elevated at the protein level. Numerous human cytokine mRNAs were also induced including MCP-1, IL-8, GRO, VEGF, GM-CSF and IL-6, which again was in line with our protein data. Pathway analysis indicated that significant numbers of the stromal mRNAs induced by DMXAA are regulated downstream of TNF-, interferon- and NFB. Our results suggest that DMXAA may have utility in combination therapy for human melanoma through the activation of pro-inflammatory signalling pathways and cytokine expression from both stromal and tumor cells, leading to haemorrhagic necrosis, neutrophil influx and growth inhibition.
Dissection of stromal and cancer cell-derived signals in melanoma xenografts before and after treatment with DMXAA.
Specimen part, Cell line
View SamplesGene expression profile of joint tissue from C3H and interval specific congenic mouse lines (ISCL) following infection with Borrelia burgdorferi
Interval-specific congenic lines reveal quantitative trait Loci with penetrant lyme arthritis phenotypes on chromosomes 5, 11, and 12.
Specimen part
View SamplesDuring mammalian gastrulation, pluripotent epiblast stem cells migrate through the primitive streak to form the multipotent progenitors of the mesoderm and endoderm germ layers. Msgn1 is a bHLH transcription factor and is a direct target gene of the Wnt/bcatenin signaling pathway. Msgn1 is expressed in the mesodermal compartment of the primitive streak and is necessary for the proper development of the mesoderm. Msgn1 mutants show defects in somitogenesis leading to a lack of trunk skeletal muscles, vertebra and ribs.
The Wnt3a/β-catenin target gene Mesogenin1 controls the segmentation clock by activating a Notch signalling program.
Specimen part, Treatment
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