X-chromosome aneuploidies have long been associated with human cancers, but causality has not been established. In mammals, X-chromosome inactivation (XCI) is triggered by Xist RNA to equalize gene expression between the sexes. Here we delete Xist in the blood compartment of mice and demonstrate that mutant females develop a highly aggressive myeloproliferative neoplasm and myelodysplastic syndrome (mixed MPN/MDS) with 100% penetrance. Significant disease components include primary myelofibrosis, leukemia, histiocytic sarcoma, and vasculitis. Xist-deficient hematopoietic stem cells (HSC) show aberrant maturation and age-dependent loss. Reconstitution experiments indicate that MPN/MDS and myelofibrosis are of hematopoietic rather than stromal origin. We propose that Xist loss results in X-reactivation and consequent genome-wide changes that lead to cancer, thereby causally linking the X-chromosome to cancer in mice. Thus, Xist RNA is not only required to maintain XCI but also suppresses cancer in vivo.
Xist RNA is a potent suppressor of hematologic cancer in mice.
Sex, Age, Specimen part
View SamplesWe compared human female hiPSC lines (all derived from IMR-90 fibroblasts) that were XIST RNA-positive and XIST RNA-negative. We also examined the gene expression patterns for 2 female hIPSCs (derived from different disease model fibroblasts) that were also negative for XIST RNA. hiPS 12D-1 is derived from Huntington's Disease patient and 6C-1 is derived from a Type I Diabetes Mellitus patient (Park et al Nature 2008).
Molecular signatures of human induced pluripotent stem cells highlight sex differences and cancer genes.
Specimen part
View SamplesThe formation of neuronal connections requires the precise guidance of developing axons towards their targets. In the Drosophila visual system, photoreceptor neurons (R cells) project from the eye into the brain. These cells are grouped into some 750 clusters comprised of eight photoreceptors or R-cells each. R cells fall into three classes, R1-R6, R7 and R8. Posterior R8 cells are the first to project axons into the brain. How these axons select a specific pathway is not known.
Robo-3--mediated repulsive interactions guide R8 axons during Drosophila visual system development.
Specimen part
View SamplesMost cell culture experiments utilize media containing fetal calf serum. Results are often interpreted regarding importance to human pathways. We studied gene expression in mouse macrophages grown in the absence of serum, and in fetal calf serum, mouse serum, and human serum using genome wide expression systems in resting conditions and after stimulation with lipopolysaccharide.
No associated publication
Specimen part, Treatment
View SamplesAffymetrix MG430 2.0 expression levels of wild-type (STHdhQ7/Q7), 3NP-treated wild-type (STHdhQ7/Q7+3-NP), and mutant (STHdhQ111/Q111) striatal cells
Unbiased gene expression analysis implicates the huntingtin polyglutamine tract in extra-mitochondrial energy metabolism.
No sample metadata fields
View SamplesProductive rearrangement of the immunoglobulin heavy chain locus triggers a major developmental checkpoint that promotes limited clonal expansion of pre-B cells, culminating in cell cycle arrest and rearrangement of the kappa () or lambda () light-chain loci. B lineage cells lacking the related transcription factors IRF-4 and IRF-8 undergo a developmental arrest at the cycling pre-B cell stage and are blocked for light-chain recombination. Using Irf-4,8-/- pre-B cells we demonstrate that two pathways converge to synergistically drive light-chain rearrangement, a process that is not simply activated by cell cycle exit. One pathway is directly dependent on IRF-4, whose expression is elevated by pre-BCR signaling. IRF-4 targets the 3 and enhancers to increase locus accessibility and positions a kappa allele away from pericentromeric heterochromatin. The other pathway is triggered by attenuation of IL-7 signaling and results in activation of the intronic enhancer via binding of the transcription factor, E2A. Intriguingly, IRF-4 regulates the expression of CXCR4 and promotes the migration of pre-B cells in response to the chemokine CXCL12. We propose that IRF-4 coordinates the two pathways regulating light-chain recombination by positioning pre-B cells away from IL-7 expressing stromal cells.
Regulation of immunoglobulin light-chain recombination by the transcription factor IRF-4 and the attenuation of interleukin-7 signaling.
No sample metadata fields
View SamplesNuclear compartmentalization appears to play an important role in regulating metazoan genes. While studies on immunoglobulin (Ig) and other loci have correlated positioning at the nuclear lamina with gene repression, the functional consequences of this compartmentalization remain untested. We devised an approach for inducible tethering of genes to the inner nuclear membrane (INM) and demonstrate with 3D DNA-ImmunoFISH, repositioning of chromosomal regions to the nuclear lamina. Relocalization requires mitotic nuclear envelope breakdown and reformation. Tethering leads to the accumulation of lamin and INM proteins but not to association with pericentromeric heterochromatin or nuclear pore complexes. Recruitment of genes to the INM can result in their transcriptional repression. Using DamID we show that as is the case for our model system, inactive Ig loci at the nuclear periphery are contacted by INM and lamina components. We propose that such molecular interactions are used to compartmentalize and limit the accessibility of Ig loci.
No associated publication
No sample metadata fields
View SamplesWe used microarrays to assess transcriptional changes in regulatory T cells upon deletion of PTEN.
No associated publication
Sex, Age
View SamplesThe goal of this experiment was to explore the extent of KIN10 (At3g01090) transcriptional regulation and identify its early target genes in Arabidopsis mesophyll protoplasts. Results suggest that KIN10 targets a remarkably broad array of genes that orchestrate transcription networks, promote catabolism and autophagy, and suppress anabolism and ribosome biogenesis. The transient expression condition ruled out secondary or long-term effects of metabolism and growth, and circumvented experimental limitations caused by redundancy and embryonic lethality observed in mammals and plants.
A central integrator of transcription networks in plant stress and energy signalling.
No sample metadata fields
View SamplesThe goal of this experiment was to investigate the early transcript changes (6h) induced by hypoxia treatment in mesophyll protoplasts. A single pair (control & hypoxia) of GeneChips was used to confirm that hypoxia treatment altered the expression of an overlapping set of genes controlled by KIN10 (At3g01090) in Arabidopsis mesophyll protoplasts.
A central integrator of transcription networks in plant stress and energy signalling.
No sample metadata fields
View Samples