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 SamplesThe vertebrate retina uses diverse neuronal cell types arrayed into complex neural circuits to extract, process and relay information from the visual scene to the higher order processing centers of the brain. Amacrine cells, a diverse class of inhibitory interneurons, are thought to mediate the majority of the processing of the visual signal that occurs within the retina. Despite morphological characterization, the number of known molecular markers of amacrine cell types is still much smaller than the 26 morphological types that have been identified. Furthermore, it is not known how this diversity arises during development. Here, we have combined in vivo genetic labeling and single cell genome-wide expression profiling to: 1) Identify specific molecular types of amacrine cells; 2) Demonstrate the molecular diversity of the amacrine cell class.
Development and diversification of retinal amacrine interneurons at single cell resolution.
No sample metadata fields
View SamplesThe goal of the project was to isolate single miRNA-expressing cells labelled by GFP reporter genes under the control of endogenous miRNA promoters and analyze expression levels of miRNA target genes in these cells. GFP-positive miRNA-expressing cells and GFP-negative cells from the rest of the embryos were purified at the same developmental stage to the cellular resolution using fluorescent activated cell sorting (FACS). Focus was on regulation by miR-206 and miR-133 in the developing somites and miR-124 in the developing central nervous system. Comparison of wild-type embryos and those lacking miRNAs revealed predicted
Coherent but overlapping expression of microRNAs and their targets during vertebrate development.
No sample metadata fields
View SamplesScaffold proteins regulate intracellular MAP kinase signaling by providing critical spatial and temporal specificity. We have shown previously that the scaffold protein MEK1 partner (MP1) is localized to late endosomes by the adaptor protein p14. Using conditional gene disruption of p14 in livers of mice we analysed protein and transcript signatures in tissue samples. Further biological network analysis predicted that the differentially expressed transcripts and proteins are involved in cell cycle progression and regulation of cellular proliferation. Although some of the here identified signatures were previously linked to phospho-ERK activity, most of them were novel targets of late endosomal p14/MP1/MEK/ERK signaling module. Finally, the proliferation defect was confirmed in a chemically induced liver regeneration model in p14 liver knock-out mice.
Comprehensive proteomic and transcriptomic characterization of hepatic expression signatures affected in p14 liver conditional knockout mice.
Specimen part
View SamplesContinuous regeneration of digestive enzyme (zymogen) secreting chief cells is a normal aspect of stomach function that is disrupted in pre-cancerous lesions. Regulation of zymogenic cell (ZC) differentiation is poorly understood. Here we profile Parietal, Pit, and Zymogenic cells for comparison and study.
The maturation of mucus-secreting gastric epithelial progenitors into digestive-enzyme secreting zymogenic cells requires Mist1.
Specimen part
View SamplesThe pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin- Sca1+ c-kit+) stem cells while committed granulocyte-monocyte progenitors (GMPs) were transformation-resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll- AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 up-regulated expression of 196 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors.
Malignant transformation initiated by Mll-AF9: gene dosage and critical target cells.
No sample metadata fields
View SamplesGene expression profiling of newborn lung tissue revealed few changes in compound FGFR3/FGFR4 deficient mice, consistent with their normal lung morphology at birth, suggesting the sequence of events leading to the phenotype initiates after birth in this model.
Fibroblast growth factor receptors control epithelial-mesenchymal interactions necessary for alveolar elastogenesis.
Age, Specimen part
View SamplesVariant late-infantile (vLINCL) and juvenile neuronal ceroid lipofuscinosis (JNCL) share clinical and pathological features, including lysosomal accumulation of mitochondrial ATP synthase subunit c, but the unrelated CLN6 and CLN3 genes may initiate disease via similar or distinct cellular processes. To gain insight into the NCL pathways, we established murine wild-type and vLINCL CbCln6nclf cerebellar cells and compared them to wild-type and JNCL CbCln3ex7/8 cerebellar cells. CbCln6nclf/nclf cells and CbCln3ex7/8/ex7/8 cells both displayed abnormally elongated mitochondria and reduced cellular ATP levels and, as cells aged to confluence, exhibited accumulation of subunit c protein in Lamp 1-positive organelles. However, at sub-confluence, endoplasmic reticulum PDI immunostain was decreased only in CbCln6nclf/nclf cells, while fluid-phase endocytosis and LysoTracker labeled vesicles were decreased in both CbCln6nclf/nclf and CbCln3ex7/8/ex7/8 cells, though only the latter cells exhibited abnormal vesicle subcellular distribution. Furthermore, unbiased gene expression analyses revealed only partial overlap in the cerebellar cell genes and pathways that were altered by the Cln3ex7/8 and Cln6nclf mutations. Thus, these data support the hypothesis that vLINCL and JNCL mutations trigger distinct processes that converge on a shared pathway, which is responsible for proper subunit c protein turnover and neuronal cell survival.
Distinct early molecular responses to mutations causing vLINCL and JNCL presage ATP synthase subunit C accumulation in cerebellar cells.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Type I and type III interferons drive redundant amplification loops to induce a transcriptional signature in influenza-infected airway epithelia.
Specimen part
View SamplesWe used microarrays to detail the global programme of gene expression in response to Influenza A (PR8) infection
Type I and type III interferons drive redundant amplification loops to induce a transcriptional signature in influenza-infected airway epithelia.
Specimen part
View Samples