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ABSTRACT: This protocol describes a method for nucleocytoplasmic protein tracking during normal cell cycle progression using unmanipulated, asynchronous cells. In contrast with prevalent traditional methods, our approach does not require time-consuming, perturbing cell synchronization or separation. To this end, we chose a single-cell approach and developed a flow cytometry assay that is applied to whole cells and isolated nuclei. Our protocol involves a stepwise biochemical fractionation procedure to purify nuclei from whole cells, conventional DNA and indirect immunostaining techniques for the dual labeling of cells and nuclei for DNA and protein, and a refined concept of flow cytometric data processing and calculation: through the specific combination of DNA and cell size analyses, G1, S and G2/M phases of the cell cycle are further dissected to establish a high-resolution map of cell cycle progression, to which protein expression in cells or nuclei is correlated. In a final data analysis step, cell cycle-related, cytoplasmic protein expression is calculated on the basis of results obtained for whole cells and isolated nuclei. A minimum of 8 h is required to complete the procedure. As the approach does not require cell type-restricting pretreatments, numerous cell types of different origin can be readily studied. Human amniotic fluid stem cells, primary human fibroblasts, immortalized mouse fibroblasts and transformed tumor cells are analyzed at comparable efficiencies, demonstrating low intercell assay variability.
Nature Protocol 02/2013; 8(3):602-26. · 8.36 Impact Factor
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ABSTRACT: Fetal cells (and cell-free, fetal DNA used for non-invasive prenatal diagnosis) are known to exist in the circulation of pregnant women. These cells exhibit stem cell properties when they differentiate at the site of injured maternal tissue, but the origin of these fetal, natural, and probably reparative cells is unknown. During pregnancy, mobilized pluripotent fetal stem cells of yet unidentified in vivo significance float in the amniotic fluid, and we argue that circulating fetal cells and the pluripotent amniotic fluid cells might share a common origin.
Trends in Molecular Medicine 01/2013; · 10.35 Impact Factor
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Karl Katholnig,
Christopher C Kaltenecker,
Hiroko Hayakawa,
Margit Rosner,
Caroline Lassnig,
Gerhard J Zlabinger,
Matthias Gaestel,
Mathias Müller, Markus Hengstschläger,
Walter H Hörl,
Jin Mo Park,
Marcus D Säemann,
Thomas Weichhart
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ABSTRACT: The MAPK p38α senses environmental stressors and orchestrates inflammatory and immunomodulatory reactions. However, the molecular mechanism how p38α controls immunomodulatory responses in myeloid cells remains elusive. We found that in monocytes and macrophages, p38α activated the mechanistic target of rapamycin (mTOR) pathway in vitro and in vivo. p38α signaling in myeloid immune cells promoted IL-10 but inhibited IL-12 expression via mTOR and blocked the differentiation of proinflammatory CD4(+) Th1 cells. Cellular stress induced p38α-mediated mTOR activation that was independent of PI3K but dependent on the MAPK-activated protein kinase 2 and on the inhibition of tuberous sclerosis 1 and 2, a negative regulatory complex of mTOR signaling. Remarkably, p38α and PI3K concurrently modulated mTOR to balance IL-12 and IL-10 expression. Our data link p38α to mTOR signaling in myeloid immune cells that is decisive for tuning the immune response in dependence on the environmental milieu.
The Journal of Immunology 01/2013; · 5.79 Impact Factor
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ABSTRACT: Of all known ribosomal proteins, the 40S ribosomal protein S6 is by far the most extensively studied. Still, little is known about some basic aspects of S6 regulation including its cell cycle-related expression and localization. Using a flow cytometric single cell approach applied to whole cells and isolated nuclei, we monitored nucleocytoplasmic expression of total and S240/4 phosphorylated S6 during unperturbed cell cycle progression, providing first evidence for a S6-specific spatiotemporal pattern and its deregulation under conditions of hyperactivated mTOR.
Amino Acids 12/2012; · 3.25 Impact Factor
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New England Journal of Medicine 11/2012; 367(18):1764-5. · 53.30 Impact Factor
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ABSTRACT: Determining the migratory and invasive capacity of tumor and stromal cells and clarifying the underlying mechanisms is most relevant for novel strategies in cancer diagnosis, prognosis, drug development and treatment. Here we shortly summarize the different modes of cell travelling and review in vitro methods, which can be used to evaluate migration and invasion. We provide a concise summary of established migration/invasion assays described in the literature, list advantages, limitations and drawbacks, give a tabular overview for convenience and depict the basic principles of the assays graphically. In many cases particular research problems and specific cell types do not leave a choice for a broad variety of usable assays. However, for most standard applications using adherent cells, based on our experience we suggest to use exclusion zone assays to evaluate migration/invasion. We substantiate our choice by demonstrating that the advantages outbalance the drawbacks e.g. the simple setup, the easy readout, the kinetic analysis, the evaluation of cell morphology and the feasibility to perform the assay with standard laboratory equipment. Finally, innovative 3D migration and invasion models including heterotypic cell interactions are discussed. These methods recapitulate the in vivo situation most closely. Results obtained with these assays have already shed new light on cancer cell spreading and potentially will uncover unknown mechanisms.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 08/2012; · 2.85 Impact Factor
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ABSTRACT: Chronic articular cartilage defects are the most common disabling conditions of humans in the western world. The incidence for cartilage defects is increasing with age and the most prominent risk factors are overweight and sports associated overloading. Damage of articular cartilage frequently leads to osteoarthritis due to the aneural and avascular nature of articular cartilage, which impairs regeneration and repair. Hence, patients affected by cartilage defects will benefit from a cell-based transplantation strategy. Autologous chondrocytes, mesenchymal stem cells and embryonic stem cells are suitable donor cells for regeneration approaches and most recently the discovery of amniotic fluid stem cells has opened a plethora of new therapeutic options. It is the aim of this review to summarize recent advances in the use of amniotic fluid stem cells as novel cell sources for the treatment of articular cartilage defects. Molecular aspects of articular cartilage formation as well as degeneration are summarized and the role of growth factor triggered signaling pathways, scaffolds, hypoxia and autophagy during the process of chondrogenic differentiation are discussed.
Stem cell reviews 08/2012; · 5.08 Impact Factor
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Benedikt Giessrigl,
Sigurd Krieger,
Margit Rosner,
Nicole Huttary,
Philipp Saiko,
Mouad Alami,
Samir Messaoudi,
Jean-François Peyrat,
Alexandre Maciuk,
Michaela Gollinger,
Sabine Kopf,
Egidijus Kazlauskas,
Peter Mazal,
Thomas Szekeres, Markus Hengstschläger,
Daumantas Matulis,
Walter Jäger,
Georg Krupitza
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ABSTRACT: Pancreas cancer cells escape most treatment options. Heat shock protein (Hsp)90 is frequently over-expressed in pancreas carcinomas and protects a number of cell-cycle regulators such as the proto-oncogene Cdc25A. We show that inhibition of Hsp90 with geldanamycin (GD) destabilizes Cdc25A independent of Chk1/2, whereas the standard drug for pancreas carcinoma treatment, gemcitabine (GEM), causes Cdc25A degradation through the activation of Chk2. Both agents applied together additively inhibit the expression of Cdc25A and the proliferation of pancreas carcinoma cells thereby demonstrating that both Cdc25A-destabilizing/degrading pathways are separated. The role of Hsp90 as stabilizer of Cdc25A in pancreas carcinoma cells is further supported by two novel synthetic inhibitors 4-tosylcyclonovobiocic acid and 7-tosylcyclonovobiocic acid and specific Hsp90AB1 (Hsp90β) shRNA. Our data show that targeting Hsp90 reduced the resistance of pancreas carcinoma cells to treatment with GEM.
Human Molecular Genetics 07/2012; 21(21):4615-27. · 7.64 Impact Factor
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ABSTRACT: The protein kinase mTOR is the central player within a pathway, which is known to be involved in the regulation of e.g., cell size, cell cycle, apoptosis, autophagy, aging and differentiation. mTOR activity responds to many signals, including cellular stress, oxygen, nutrient availability, energy status and growth factors. Deregulation of this enzyme is causatively involved in the molecular development of monogenic human diseases, cancer, obesity, type 2 diabetes or neurodegeneration. Recently, mTOR has also been demonstrated to control stem cell homeostasis. A more detailed investigation of this new mTOR function will be of highest relevance to provide more explicit insights into stem cell regulation in the near future. Different cellular tools, including adult stem cells, embryonic stem cells or induced pluripotent stem cells could be used to investigate the role of mTOR in mammalian stem cell biology. Here we discuss the potential of amniotic fluid stem cells to become a promising cellular model to study the role of signaling cascades in stem cells homeostasis.
Organogenesis 07/2012; 8(3). · 2.17 Impact Factor
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ABSTRACT: The heavy metals mercury, lead, and cadmium are toxicants, which are well-known to cross the placenta and to accumulate in fetal tissues. Prenatal exposure to mercury and lead poses a health threat particularly to the developing brain. Fetal exposures to lead and cadmium correlate with reduced birth weight and birth size. The placental passage of cadmium is limited suggesting a partial barrier for this metal. It is very likely that metallothionein is responsible for placental storage of the metals especially of cadmium. It is unclear, however, which proteins are involved in placental uptake and efflux of the metals and where the transporters are located at the placental barrier. Hence, only certain aspects of placental metal toxicokinetics are known so far. The metals have also been shown to adversely affect placental functions. Both metal-specific placental transfer and impairment of placental function can explain the relationships between prenatal metal exposures and adverse effects on intrauterine growth and (neuro)development.
Wiener Medizinische Wochenschrift 05/2012; 162(9-10):201-6.
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ABSTRACT: Tuberous sclerosis complex (TSC) is a common genetic disorder in which affected individuals develop mental retardation, developmental
brain defects and seizures. The TSC gene products, hamartin and tuberin, form a complex, of which tuberin is assumed to be
the functional component being involved in a wide variety of different cellular processes. Here we report that tuberin protein
levels are decreased in the frontal cortex of patients with Alzheimer’s disease. In addition, tuberin levels are also decreased
in Down syndrome brain samples positive for β-amyloid plaques and neurofibrillary tangles. Analysis of NeuN revealed that
this regulation is not a consequence of differences in the amount of postmitotic neurons. This first connection of tuberin
to another common disease beside TSC stimulates new approaches to investigate the molecular development and to establish new
therapeutic strategies.
Neurochemical Research 04/2012; 30(11):1413-1419. · 2.24 Impact Factor
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ABSTRACT: Although the involvement of the mTOR (mammalian target of rapamycin) system in memory processes has been reported, information on the effect of rapamycin on spatial learning and memory is limited. It was therefore the aim of the study to show the effect of parenteral rapamycin administration to C57BL/6J mice on performance in the multiple T-maze (MTM) and to determine hippocampal mTOR activity. Rapamycin-treated and -untreated/trained/probed mice are the main part of the experiment considering retrieval and acquisition or consolidation of spatial memory. Six hours following euthanasia hippocampi were extirpated and used for evaluation of mTOR activity as represented by hippocampal levels of S6 protein and its phosphorylated active form (phospho S6 protein, S240,244), a read out of mTOR complex 1 activity. Mice given i.p. rapamycin learned the task of the MTM but failed at the probe trial, showing absence of the phosphorylated active form of S6 protein, indicating inhibition of mTOR activity. Herein, impairing effects of rapamycin on retrieval but not on acquisition or consolidation of spatial memory are shown. Deficient memory retrieval was paralleled by inhibition of mTOR complex 1 activity. The current study extends knowledge on rapamycin in memory mechanisms and challenges work on deeper insights into the role of mTOR in different phases of memory formation and retrieval.
Behavioural brain research 04/2012; 229(2):320-4. · 3.22 Impact Factor
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ABSTRACT: Male infertility is a major public health issue predominantly caused by defects in germ cell development. In the past, studies on the genetic regulation of spermatogenesis as well as on negative environmental impacts have been hampered by the fact that human germ cell development is intractable to direct analysis in vivo. Compared with model organisms including mice, there are fundamental differences in the molecular processes of human germ cell development. Therefore, an in vitro model mimicking human sperm formation would be an extremely valuable research tool. In the recent past, both human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells have been reported to harbour the potential to differentiate into primordial germ cells and gametes. We here discuss the possibility to use human amniotic fluid stem (AFS) cells as a biological model. Since their discovery in 2003, AFS cells have been characterized to differentiate into cells of all three germ layers, to be genomically stable, to have a high proliferative potential and to be non-tumourigenic. In addition, AFS cells are not subject of ethical concerns. In contrast to iPS cells, AFSs cells do not need ectopic induction of pluripotency, which is often associated with only imperfectly cleared epigenetic memory of the source cells. Since AFS cells can be derived from amniocentesis with disease-causing mutations and can be transfected with high efficiency, they could be used in probing gene functions for spermatogenesis and in screening for male reproductive toxicity.
Asian Journal of Andrology 03/2012; 14(2):247-50. · 1.52 Impact Factor
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Cell cycle (Georgetown, Tex.) 02/2012; 11(3):420-1. · 5.36 Impact Factor
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ABSTRACT: Information on very high pressure (VHP) effects on proteins is limited and therefore effects of VHP on chemistry, structure and function of two model proteins in medical use were studied. VHP (8 GPa) application to l-asparaginase (L-ASNase) resulted in faster mobility on clear native gels. VHP induced generation of lower-MW forms of L-ASNase but VHP treatment did not deteriorate asparaginase activity. Electrophoretic patterns in native and denaturing gels were comparable for untreated and pressurized recombinant human growth hormone (rhGH). rhGH function, however, was deteriorated as shown by a bioassay. In L-ASNase and rhGH a series of protein modifications and amino acid exchanges (indicating cleavage of covalent bonds) were revealed that may probably lead to functional and conformational changes. The findings have implications in protein chemistry, structure, and function and are useful for designing biotechnological applications of protein products.
The Journal of Physical Chemistry B 01/2012; 116(3):1100-10. · 3.70 Impact Factor
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ABSTRACT: The existence of stem cells in human amniotic fluid was reported for the first time almost ten years ago. Since this discovery, the knowledge about these cells has increased dramatically. Today, amniotic fluid stem (AFS) cells are widely accepted as a new powerful tool for basic research as well as for the establishment of new stem-cell-based therapy concepts. It is possible to generate monoclonal genomically stable AFS cell lines harboring high proliferative potential without raising ethical issues. Many different groups have demonstrated that AFS cells can be differentiated into all three germ layer lineages, what is of relevance for both, the scientific and therapeutical usage of these cells. Of special importance for the latter is the fact that AFS cells are less tumorigenic than other pluripotent stem cell types. In this paper, we have summarized the current knowledge about this relatively young scientific field. Furthermore, we discuss the relevant future perspectives of this promising area of stem cell research focusing on the next important questions, which need to be answered.
Stem cells international. 01/2012; 2012:741810.
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ABSTRACT: Subcellular localization constitutes the environment in which proteins act. It tightly controls access to and availability of different types of molecular interacting partners and is therefore a major determinant of protein function and regulation. Originally thought to be a mere cytoplasmic kinase the mammalian target of rapamycin (mTOR) has recently been localized to various intracellular compartments including the nucleus and specific components of the endomembrane system such as lysosomes. The identification of essential binding partners and the structural and functional partitioning of mTOR into two distinct multiprotein complexes warrant the detailed investigation of the subcellular localization of mTOR as part of mTORC1 and mTORC2. Upon establishment of experimental conditions allowing cytoplasmic/nuclear fractionation at high purity and maximum mTOR complex recovery we have previously shown that the mTOR/raptor complex (mTORC1) is predominantly cytoplasmic whereas the mTOR/rictor complex (mTORC2) is abundant in both compartments. Moreover, the mTORC2 complex components rictor and sin1 are dephosphorylated and dynamically distributed between the cytoplasm and the nucleus upon long-term treatment with the mTOR-inhibitor rapamycin. These findings further demonstrate that the here presented and detailly described fractionation procedure is a valuable tool to study protein localization and cytoplasmic/nuclear protein shuttling in the context of expanding mTOR signalling.
Methods in molecular biology (Clifton, N.J.) 01/2012; 821:105-24.
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ABSTRACT: Embryoid bodies (EBs) are three-dimensional multicellular aggregates allowing the in vitro investigation of stem-cell differentiation processes mimicking early embryogenesis. Human amniotic fluid stem (AFS) cells harbor high proliferation potential, do not raise the ethical issues of embryonic stem cells, have a lower risk for tumor development, do not need exogenic induction of pluripotency and are chromosomal stable. Starting from a single human AFS cell, EBs can be formed accompanied by the differentiation into cells of all three embryonic germ layers. Here, we report that siRNA-mediated knockdown of the endogenous tuberous sclerosis complex-2 (TSC2) gene product tuberin or of proline-rich Akt substrate of 40 kDa (PRAS40), the two major negative regulators of mammalian target of rapamycin (mTOR), leads to massive apoptotic cell death during EB development of human AFS cells without affecting the endodermal, mesodermal and ectodermal cell differentiation spectrum. Co-knockdown of endogenous mTOR demonstrated these effects to be mTOR-dependent. Our findings prove this enzyme cascade to be an essential anti-apoptotic gatekeeper of stem-cell differentiation during EB formation. These data allow new insights into the regulation of early stem-cell maintenance and differentiation and identify a new role of the tumor suppressor tuberin and the oncogenic protein PRAS40 with the relevance for a more detailed understanding of the pathogenesis of diseases associated with altered activities of these gene products.
Human Molecular Genetics 11/2011; 21(5):1049-61. · 7.64 Impact Factor
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ABSTRACT: Owing to growing rates of diabetes, hypertension and the ageing population, the prevalence of end-stage renal disease, developed from earlier stages of chronic kidney disease, and of acute renal failure is dramatically increasing. Dialysis and preferable renal transplantation are widely applied therapies for this incurable condition. However these options are limited because of morbidity, shortage of compatible organs and costs. Therefore, stem cell-based approaches are becoming increasingly accepted as an alternative therapeutic strategy.
This review summarizes the current findings on the nephrogenic potential of amniotic fluid stem (AFS) cells and their putative implications for clinical applications and for studies on specific human genetic diseases.
Since their discovery in 2003, AFS cells have been shown to be pluripotent with the potential to form embryoid bodies. Compared to adult stem cells, induced pluripotent stem cells or embryonic stem cells, AFS cells harbour a variety of advantages, such as their high differentiation and proliferative potential, no need for ectopic induction of pluripotency and no somatic mutations and epigenetic memory of source cells, and no tumourigenic potential and associated ethical controversies, respectively.
Recently, the results of different independent studies provided evidence that AFS cells could indeed be a powerful tool for renal regenerative medicine.
European Journal of Clinical Investigation 10/2011; 42(6):677-84. · 3.02 Impact Factor
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Cell cycle (Georgetown, Tex.) 10/2011; 10(20):3608-10. · 5.36 Impact Factor
