Institute of Stem Cell Research

Germany

Institute of Stem Cell Research

Germany
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News Article | May 5, 2017
Site: www.eurekalert.org

Many specialized cells, such as in the skin, gut or blood, have a lifespan of only a few days. Therefore, steady replenishment of these cells is indispensable. They arise from so-called "adult" stem cells that divide continuously. In addition, there is a group of very special stem cells in the bone marrow that were first discovered in 2008 by a research team led by Andreas Trumpp, who is a division head at the DKFZ and director of HI-STEM. These cells remain in a kind of dormancy most of the time and only become active in an emergency such as bacterial or viral infections, heavy blood loss, or in the wake of chemotherapy. Once their work is done, the body sends its most potent stem cells back to sleep. The scientists assume that this protects them from dangerous mutations that may lead to leukemia. The mechanisms that activate these special stem cells or make them go back to sleep after their work is done have remained elusive until now. The scientists have now identified retinoic acid, a vitamin A metabolite, as a crucial factor in this process. If this substance is absent, active stem cells are unable to return to a dormant state and mature into specialized blood cells instead. This means that they are lost as a reservoir. This was shown in studies with specially bred mice whose dormant stem cells are green fluorescent. "If we feed these mice on a vitamin A deficient diet for some time, this leads to a loss of the stem cells," said Nina Cabezas-Wallscheid, who is the first author of the publication. "Thus, we can prove for the first time that vitamin A has a direct impact on blood stem cells." This finding not only enhances our understanding of the development of blood cells, it also sheds new light on prior studies that demonstrate that vitamin A deficiency impairs the immune system. "This shows how vitally important it is to have a sufficient intake of vitamin A from a balanced diet," Cabezas-Wallscheid emphasized. The body cannot produce its own vitamin A. The scientists also have hopes for new prospects in cancer treatment. There is evidence that cancer cells, like healthy stem cells, also rest in a state of dormancy. When dormant, their metabolism is almost completely shut down -- and this makes them resistant to chemotherapy. "Once we understand in detail how vitamin A or retinoic acid, respectively, sends normal and malignant stem cells into dormancy, we can try to turn the tables," explained Trumpp. "If we could make cancer cells temporarily enter an active state, we could thus make them vulnerable to modern therapies." In addition, in collaboration with colleagues from the European Bioinformatics Institute in Cambridge, the team performed genome-wide analyses of single cells and discovered that the transition from dormant to active stem cells and then on to progenitor cells is a continuous one and follows a different path for each individual cell. So far, scientists had assumed that specific cell types develop step by step in a defined pattern. This finding revolutionizes the previous concept of how cell differentiation in the body takes place. The Heidelberg Institute of Stem Cell Research and Experimental Medicine (HI-STEM) is a partnership of the DKFZ and the Dietmar Hopp Foundation. An image for this press release is available at: http://www. Caption: Vitamin A, which is contained in foods like carrots, broccoli and fish, regulates hematopoietic stem cells. Note on use of images related to press releases Use is free of charge. The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) permits one-time use in the context of reporting about the topic covered in the press release. Images have to be cited as follows: "Source: Iris Joval/DKFZ". Distribution of images to third parties is not permitted unless prior consent has been obtained from DKFZ's Press Office (phone: ++49-(0)6221 42 2854, E-mail: presse@dkfz.de). Any commercial use is prohibited. The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) with its more than 3,000 employees is the largest biomedical research institute in Germany. At DKFZ, more than 1,000 scientists investigate how cancer develops, identify cancer risk factors and endeavor to find new strategies to prevent people from getting cancer. They develop novel approaches to make tumor diagnosis more precise and treatment of cancer patients more successful. The staff of the Cancer Information Service (KID) offers information about the widespread disease of cancer for patients, their families, and the general public. Jointly with Heidelberg University Hospital, DKFZ has established the National Center for Tumor Diseases (NCT) Heidelberg, where promising approaches from cancer research are translated into the clinic. In the German Consortium for Translational Cancer Research (DKTK), one of six German Centers for Health Research, DKFZ maintains translational centers at seven university partnering sites. Combining excellent university hospitals with high-profile research at a Helmholtz Center is an important contribution to improving the chances of cancer patients. DKFZ is a member of the Helmholtz Association of National Research Centers, with ninety percent of its funding coming from the German Federal Ministry of Education and Research and the remaining ten percent from the State of Baden-Württemberg.


Britschgi A.,Friedrich Miescher Institute for Biomedical Research | Duss S.,Friedrich Miescher Institute for Biomedical Research | Kim S.,Genomics Institute of the Novartis Research Foundation | Couto J.P.,Friedrich Miescher Institute for Biomedical Research | And 23 more authors.
Nature | Year: 2017

Cell fate perturbations underlie many human diseases, including breast cancer. Unfortunately, the mechanisms by which breast cell fate are regulated are largely unknown. The mammary gland epithelium consists of differentiated luminal epithelial and basal myoepithelial cells, as well as undifferentiated stem cells and more restricted progenitors. Breast cancer originates from this epithelium, but the molecular mechanisms that underlie breast epithelial hierarchy remain ill-defined. Here, we use a high-content confocal image-based short hairpin RNA screen to identify tumour suppressors that regulate breast cell fate in primary human breast epithelial cells. We show that ablation of the large tumour suppressor kinases (LATS) 1 and 2 (refs 5, 6), which are part of the Hippo pathway, promotes the luminal phenotype and increases the number of bipotent and luminal progenitors, the proposed cells-of-origin of most human breast cancers. Mechanistically, we have identified a direct interaction between Hippo and oestrogen receptor-α (ERα) signalling. In the presence of LATS, ERα was targeted for ubiquitination and Ddb1-cullin4-associated-factor 1 (DCAF1)-dependent proteasomal degradation. Absence of LATS stabilized ERα and the Hippo effectors YAP and TAZ (hereafter YAP/TAZ), which together control breast cell fate through intrinsic and paracrine mechanisms. Our findings reveal a non-canonical (that is, YAP/TAZ-independent) effect of LATS in the regulation of human breast cell fate. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.


Saragusty J.,The Leibniz Institute for Zoo and Wildlife ResearchBerlinGermany | Diecke S.,Max Delbrück Center for Molecular Medicine | Drukker M.,Institute of Stem Cell Research | Durrant B.,San Diego Zoo Institute for Conservation ResearchEscondido | And 11 more authors.
Zoo Biology | Year: 2016

With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road map that, if successfully implemented, would ultimately lead to a self-sustaining population of an extremely endangered species are outlined here. The ideas discussed here, while centered on the northern white rhinoceros, are equally applicable, after proper adjustments, to other mammals on the brink of extinction. Through implementation of these ideas we hope to establish the foundation for reversal of some of the effects of what has been termed the sixth mass extinction event in the history of Earth, and the first anthropogenic one. Zoo Biol. XX:XX-XX, 2016. © 2016 Wiley Periodicals, Inc.


PubMed | Friedrich Miescher Institute for Biomedical Research, Cantonal Hospital Baselland, University of Zürich, Novartis and 2 more.
Type: | Journal: Nature | Year: 2017

Cell fate perturbations underlie many human diseases, including breast cancer. Unfortunately, the mechanisms by which breast cell fate are regulated are largely unknown. The mammary gland epithelium consists of differentiated luminal epithelial and basal myoepithelial cells, as well as undifferentiated stem cells and more restricted progenitors. Breast cancer originates from this epithelium, but the molecular mechanisms that underlie breast epithelial hierarchy remain ill-defined. Here, we use a high-content confocal image-based short hairpin RNA screen to identify tumour suppressors that regulate breast cell fate in primary human breast epithelial cells. We show that ablation of the large tumour suppressor kinases (LATS) 1 and 2 (refs 5, 6), which are part of the Hippo pathway, promotes the luminal phenotype and increases the number of bipotent and luminal progenitors, the proposed cells-of-origin of most human breast cancers. Mechanistically, we have identified a direct interaction between Hippo and oestrogen receptor- (ER) signalling. In the presence of LATS, ER was targeted for ubiquitination and Ddb1-cullin4-associated-factor 1 (DCAF1)-dependent proteasomal degradation. Absence of LATS stabilized ER and the Hippo effectors YAP and TAZ (hereafter YAP/TAZ), which together control breast cell fate through intrinsic and paracrine mechanisms. Our findings reveal a non-canonical (that is, YAP/TAZ-independent) effect of LATS in the regulation of human breast cell fate.


Petrezselyova S.,Academy of Sciences of the Czech Republic | Kinsky S.,Academy of Sciences of the Czech Republic | Truban D.,Academy of Sciences of the Czech Republic | Sedlacek R.,Academy of Sciences of the Czech Republic | And 2 more authors.
Cellular and Molecular Biology Letters | Year: 2015

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) technology has brought rapid progress in mammalian genome editing (adding, disrupting or changing the sequence of specific sites) by increasing the frequency of targeted events. However, gene knock-in of DNA cassettes by homologous recombination still remains difficult due to the construction of targeting vectors possessing large homology arms (from 2 up to 5 kb). Here, we demonstrate that in mouse embryonic stem cells the combination of CRISPR/Cas9 technology and targeting vectors with short homology arms (~ 0.3 kb) provides sufficient specificity for insertion of fluorescent reporter cassettes into endogenous genes with similar efficiency as those with large conventional vectors. Importantly, we emphasize the necessity of thorough quality control of recombinant clones by combination of the PCR method, Southern hybridization assay and sequencing to exclude undesired mutations. In conclusion, our approach facilitates programmed integration of exogenous DNA sequences at a target locus and thus could serve as a basis for more sophisticated genome engineering approaches, such as generation of reporters and conditional knock-out alleles. © 2016 University of Wroclaw, Poland.


Chau Y.-Y.,Western Research Institute | Brownstein D.,Queens Medical Research Institute | Mjoseng H.,University of Edinburgh | Lee W.-C.,Chang Gung University | And 13 more authors.
PLoS Genetics | Year: 2011

There is much interest in the mechanisms that regulate adult tissue homeostasis and their relationship to processes governing foetal development. Mice deleted for the Wilms' tumour gene, Wt1, lack kidneys, gonads, and spleen and die at mid-gestation due to defective coronary vasculature. Wt1 is vital for maintaining the mesenchymal-epithelial balance in these tissues and is required for the epithelial-to-mesenchyme transition (EMT) that generates coronary vascular progenitors. Although Wt1 is only expressed in rare cell populations in adults including glomerular podocytes, 1% of bone marrow cells, and mesothelium, we hypothesised that this might be important for homeostasis of adult tissues; hence, we deleted the gene ubiquitously in young and adult mice. Within just a few days, the mice suffered glomerulosclerosis, atrophy of the exocrine pancreas and spleen, severe reduction in bone and fat, and failure of erythropoiesis. FACS and culture experiments showed that Wt1 has an intrinsic role in both haematopoietic and mesenchymal stem cell lineages and suggest that defects within these contribute to the phenotypes we observe. We propose that glomerulosclerosis arises in part through down regulation of nephrin, a known Wt1 target gene. Protein profiling in mutant serum showed that there was no systemic inflammatory or nutritional response in the mutant mice. However, there was a dramatic reduction in circulating IGF-1 levels, which is likely to contribute to the bone and fat phenotypes. The reduction of IGF-1 did not result from a decrease in circulating GH, and there is no apparent pathology of the pituitary and adrenal glands. These findings 1) suggest that Wt1 is a major regulator of the homeostasis of some adult tissues, through both local and systemic actions; 2) highlight the differences between foetal and adult tissue regulation; 3) point to the importance of adult mesenchyme in tissue turnover. © 2011 Chau et al.


Hesse M.,University of Bonn | Raulf A.,University of Bonn | Pilz G.-A.,Institute of Stem Cell Research | Haberlandt C.,University of Bonn | And 14 more authors.
Nature Communications | Year: 2012

Current approaches to monitor and quantify cell division in live cells, and reliably distinguish between acytokinesis and endoreduplication, are limited and complicate determination of stem cell pool identities. Here we overcome these limitations by generating an in vivo reporter system using the scaffolding protein anillin fused to enhanced green fluorescent protein, to provide high spatiotemporal resolution of mitotic phase. This approach visualizes cytokinesis and midbody formation as hallmarks of expansion of stem and somatic cells, and enables distinction from cell cycle variations. High-resolution microscopy in embryonic heart and brain tissues of enhanced green fluorescent protein-anillin transgenic mice allows live monitoring of cell division and quantitation of cell cycle kinetics. Analysis of cell division in hearts post injury shows that border zone cardiomyocytes in the infarct respond with increasing ploidy, but not cell division. Thus, the enhanced green fluorescent protein-anillin system enables monitoring and measurement of cell division in vivo and markedly simplifies in vitro analysis in fixed cells. © 2012 Macmillan Publishers Limited. All rights reserved.


Burtscher I.,Helmholtz Center Munich | Burtscher I.,Institute of Stem Cell Research | Barkey W.,Helmholtz Center Munich | Barkey W.,Institute of Stem Cell Research | And 2 more authors.
Genesis | Year: 2013

The Foxa2-winged helix/forkhead box transcription factor (TF) is absolutely required for endoderm formation and organogenesis. Foxa2 plays essential roles during lung, liver, pancreas, and gastrointestinal tract development and regulates cell-type specific programs in the adult organism. To specifically address Foxa2 function during organ development and homeostasis, we generated a Foxa2-Venus fusion (FVF) reporter protein by gene targeting in embryonic stem (ES) cells. The FVF knock-in reporter is expressed under endogenous Foxa2 control and the fluorescent protein fusion does not interfere with TF function, as homozygous mice are viable and fertile. Moreover, the FVF protein localizes to the nucleus, associates with chromatin during mitosis, and reflects the endogenous Foxa2 protein distribution pattern in several tissues in heterozygous animals. Importantly, live-cell imaging on single-cell level of the FVF and Sox17-Cherry fusion double knock-in reporter ES cell line reveals the dynamics of endoderm TF accumulation during ES cell differentiation. The FVF reporter also allowed us to identify the endoderm progenitors during gastrulation and to visualize the different branching morphogenesis modes of the lung and pancreas epithelium in ex vivo embryo and organ cultures. In summary, the generation of the FVF reporter line adds an important new tool to visualize and analyse endoderm-derived organ development and homeostasis on the cellular and molecular level. © 2013 Wiley Periodicals, Inc.


PubMed | University College London and Institute of Stem Cell Research
Type: Journal Article | Journal: Nature reviews. Genetics | Year: 2016

Myriads of epigenomic features have been comprehensively profiled in health and disease across cell types, tissues and individuals. Although current epigenomic approaches can infer function for chromatin marks through correlation, it remains challenging to establish which marks actually have causative roles in gene regulation and other processes. After revisiting how classical approaches have addressed this question in the past, we discuss the current state of epigenomic profiling and how functional information can be indirectly inferred. We also present new approaches that promise definitive functional answers, which are collectively referred to as epigenome editing. In particular, we explore CRISPR-based technologies for single-locus and multi-locus manipulation. Finally, we discuss which level of function can be achieved with each approach and introduce emerging strategies for high-throughput progression from profiles to function.

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