To guarantee blood supply throughout adult life hematopoietic stem cells (HSCs) need to carefully balance between self-renewing cell divisions and quiescence. Identification of genes controlling HSC self-renewal is of utmost importance given that HSCs are the only stem cells with broad clinical applications. Transcription factor PU.1 is one of the major regulators of myeloid and lymphoid development. Recent reports suggest that PU.1 mediates its functions via gradual expression level changes rather than binary on/off states. So far, this has not been considered in any study of HSCs and thus, PU.1s role in HSC function has remained largely unclear. Here we demonstrate using hypomorphic mice with an engineered disruption of an autoregulatory feedback loop that decreased PU.1 levels resulted in loss of key HSC functions, all of which could be fully rescued by restoration of proper PU.1 levels via a human PU.1 transgene. Mechanistically, we found excessive HSC cell divisions and altered expression of cell cycle regulators whose promoter regions were bound by PU.1 in normal HSCs. Adequate PU.1 levels were maintained by a mechanism of direct autoregulation restricted to HSCs through a physical interaction of a -14kb enhancer with the proximal promoter. Our findings identify PU.1 as novel regulator controling the switch between cell division and quiescence in order to prevent exhaustion of HSCs. Given that even moderate level changes greatly impact stem cell function, our data suggest important therapeutic implications for leukemic patients with reduced PU.1 levels. Moreover, we provide first proof, that autoregulation of a transcription factor, PU.1, has a crucial function in vivo. We anticipate that our concept of how autoregulation forms an active chromosomal conformation will impact future research on transcription factor networks regulating stem cell fate.
Sustained PU.1 levels balance cell-cycle regulators to prevent exhaustion of adult hematopoietic stem cells.
Specimen part
View SamplesMore than 2,000 genes appear to be upregulated or downregulated in skeletal muscle of mice with constitutive knockout of myostatin (Steelman et al., FASEB J 20:580-2, 2006). This study was done to determine whether inhibition of myostatin activity in mature mice has similar effects on the pattern of gene expression.
Stimulation of skeletal muscle myofibrillar protein synthesis, p70 S6 kinase phosphorylation, and ribosomal protein S6 phosphorylation by inhibition of myostatin in mature mice.
No sample metadata fields
View SamplesAcetaminophen (APAP) is the most widely used analgesic in the United States. Its acute overdose causes liver damage by inducing localized centrilobular cell death. Because of widespread use, APAP toxicity has become the most frequent cause of acute liver failure. Many factors have been associated with the susceptibility of APAP-induced liver injuries, however, few of them have been confirmed and used in the clinical setting.
An integrative genomic analysis identifies Bhmt2 as a diet-dependent genetic factor protecting against acetaminophen-induced liver toxicity.
Specimen part, Time
View SamplesRNA from 5 mice with postdevelopmental knockout of myostatin and 5 mice with normal myostatin expression was analyzed with comprehensive oligonucleotide microarrays. Myostatin depletion affected the expression of several hundred genes at nominal P < 0.01, but fewer than a hundred effects were statistically significant according to a more stringent criterion (false discovery rate < 5%). Most of the effects were less than 1.5-fold in magnitude. In contrast to previously-reported effects of constitutive myostatin knockout, postdevelopmental knockout did not downregulate expression of genes encoding slow isoforms of contractile proteins or genes encoding proteins involved in energy metabolism. Several collagen genes were expressed at lower levels in the myostatin-deficient muscles, and this led to reduced tissue collagen levels as reflected by hydroxyproline content. Myostatin knockout tended to down-regulate the expression of sets of genes with promoter motifs for Smad3, Smad4, myogenin, NF-B, serum response factor, and numerous other transcription factors. Main conclusions: in mature muscle, myostatin is a key transcriptional regulator of collagen genes, but not genes encoding contractile proteins or genes encoding proteins involved in energy metabolism.
Skeletal muscle gene expression after myostatin knockout in mature mice.
Sex, Age, Specimen part
View SamplesThe E-protein transcription factors E2A and HEB play important roles at several stages of hematopoiesis. However, the exact mechanism for theire action and the main targets in the LY6D negative common lymphoid progentior (CLP) compartment remains unknown. By adressing this question, we will gain important infromation regarding the early events leading to B-cell specification.
The transcription factors E2A and HEB act in concert to induce the expression of FOXO1 in the common lymphoid progenitor.
Specimen part
View SamplesIn order to investigate molecular events involved in the regulation of lymphoid lineage commitment, we crossed lamda5 reporter transgenic mice to mice where the GFP gene is inserted into the Rag1 locus. This allowed us to sub-fractionate common lymphoid progenitors (CLPs) and pre-pro-B cells into lamda5-Rag1low, lamda5-Rag1high and lamda5+Rag1high cells. Clonal in vitro differentiation analysis demonstrated that Rag1low cells gave rise to B/T and NK cells. Rag1high cells displayed reduced NK-cell potential with preserved capacity to generate B- and T-lineage cells while the lamda5+ cells were B-lineage restricted. Ebf1 and Pax5 expression was largely confined to the Rag1high populations. These cells also expressed a higher level of the surface protein LY6D providing an additional tool for the analysis of early lymphoid development. These data suggest that the classical CLP compartment composes a mixture of cells with more or less restricted lineage potentials opening new possibilities to investigate early hematopoiesis.
Single-cell analysis of the common lymphoid progenitor compartment reveals functional and molecular heterogeneity.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Adult rat bones maintain distinct regionalized expression of markers associated with their development.
Sex, Specimen part, Treatment
View SamplesPilot study
Adult rat bones maintain distinct regionalized expression of markers associated with their development.
Sex, Specimen part
View SamplesWe sequenced liver mRNA isolated from biliatresone-treated zebrafish larvae and DMSO-treated controls in order to elucidate the molecular pathways induced by biliatresone, a biliary toxin that is responsible for outbreaks of biliary atresia in Australian liverstock. Overall design: Liver mRNA profiles of biliatresone-treated zebrafish larvae and DMSO-treated controls were generated by deep sequencing, in duplicates.
Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish.
No sample metadata fields
View SamplesThe cancer-risk associated rs6983267 single nucleotide polymorphism (SNP) and the accompanying long non-coding RNA CCAT2 in the highly amplified 8q24.21 region has been implicated in cancer predisposition, though causality has not been established. Here, using allele-specific CCAT2 transgenic mice, we demonstrate that CCAT2 overexpression leads to spontaneous myeloid malignancies. CCAT2 is overexpressed in bone marrow and peripheral blood of myelodysplastic/myeloproliferative neoplasms (MDS/MPN) patients. CCAT2 induces global deregulation of gene expression by downregulating EZH2 in vitro and in vivo in an allele-specific manner. We also identified a novel disease-specific RNA mutation (named DNA-to-RNA allelic imbalance, DRAI) at the SNP locus in MDS/MPN patients and CCAT2-transgenic mice. The RNA transcribed from the SNP locus in malignant hematopoietic cells have different allelic composition from the corresponding genomic DNA, a phenomenon rarely observed in normal cells. Our findings provide fundamental insights into the functional role of rs6983267 SNP and CCAT2 in myeloid malignancies.
Cancer-associated rs6983267 SNP and its accompanying long noncoding RNA <i>CCAT2</i> induce myeloid malignancies via unique SNP-specific RNA mutations.
Specimen part
View Samples