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Sample records for affecting cell fate

  1. Single-cell mass spectrometry reveals small molecules that affect cell fates in the 16-cell embryo

    PubMed Central

    Onjiko, Rosemary M.; Moody, Sally A.; Nemes, Peter

    2015-01-01

    Spatial and temporal changes in molecular expression are essential to embryonic development, and their characterization is critical to understand mechanisms by which cells acquire different phenotypes. Although technological advances have made it possible to quantify expression of large molecules during embryogenesis, little information is available on metabolites, the ultimate indicator of physiological activity of the cell. Here, we demonstrate that single-cell capillary electrophoresis-electrospray ionization mass spectrometry is able to test whether differential expression of the genome translates to the domain of metabolites between single embryonic cells. Dissection of three different cell types with distinct tissue fates from 16-cell embryos of the South African clawed frog (Xenopus laevis) and microextraction of their metabolomes enabled the identification of 40 metabolites that anchored interconnected central metabolic networks. Relative quantitation revealed that several metabolites were differentially active between the cell types in the wild-type, unperturbed embryos. Altering postfertilization cytoplasmic movements that perturb dorsal development confirmed that these three cells have characteristic small-molecular activity already at cleavage stages as a result of cell type and not differences in pigmentation, yolk content, cell size, or position in the embryo. Changing the metabolite concentration caused changes in cell movements at gastrulation that also altered the tissue fates of these cells, demonstrating that the metabolome affects cell phenotypes in the embryo. PMID:25941375

  2. Hyaluronic acid hydrogel stiffness and oxygen tension affect cancer cell fate and endothelial sprouting

    PubMed Central

    Shen, Yu-I; Abaci, Hasan E.; Krupsi, Yoni; Weng, Lien-Chun; Burdick, Jason A.; Gerecht, Sharon

    2014-01-01

    Three-dimensional (3D) tissue culture models may recapitulate aspects of the tumorigenic microenvironment in vivo, enabling the study of cancer progression in vitro. Both hypoxia and matrix stiffness are known to regulate tumor growth. Using a modular culture system employing an acrylated hyaluronic acid (AHA) hydrogel, three hydrogel matrices with distinctive degrees of viscoelasticity — soft (78±16 Pa), medium (309± 57 Pa), and stiff (596± 73 Pa) — were generated using the same concentration of adhesion ligands. Oxygen levels within the hydrogel in atmospheric (21 %), hypoxic (5 %), and severely hypoxic (1 %) conditions were assessed with a mathematical model. HT1080 fibrosarcoma cells, encapsulated within the AHA hydrogels in high densities, generated nonuniform oxygen distributions, while lower cell densities resulted in more uniform oxygen distributions in the atmospheric and hypoxic environments. When we examined how varying viscoelasticity in atmospheric and hypoxic environments affects cell cycles and the expression of BNIP3 and BNIP3L (autophagy and apoptosis genes), and GLUT-1 (a glucose transport gene), we observed that HT1080 cells in 3D hydrogel adapted better to hypoxic conditions than those in a Petri dish, with no obvious correlation to matrix viscoelasticity, by recovering rapidly from possible autophagy/apoptotic events and alternating metabolism mechanisms. Further, we examined how HT1080 cells cultured in varying viscoelasticity and oxygen tension conditions affected endothelial sprouting and invasion. We observed that increased matrix stiffness reduced endothelial sprouting and invasion in atmospheric conditions; however, we observed increased endothelial sprouting and invasion under hypoxia at all levels of matrix stiffness with the upregulation of vascular endothelial growth factor (VEGF) and angiopoeitin-1 (ANG-1). Overall, HT1080 cells encapsulated in the AHA hydrogels under hypoxic stress recovered better from apoptosis and

  3. Osteoprogenitor cells from bone marrow and cortical bone: understanding how the environment affects their fate.

    PubMed

    Corradetti, Bruna; Taraballi, Francesca; Powell, Sebastian; Sung, David; Minardi, Silvia; Ferrari, Mauro; Weiner, Bradley K; Tasciotti, Ennio

    2015-05-01

    Bone is a dynamic organ where skeletal progenitors and hematopoietic cells share and compete for space. Presumptive mesenchymal stem cells (MSC) have been identified and harvested from the bone marrow (BM-MSC) and cortical bone fragments (CBF-MSC). In this study, we demonstrate that despite the cells sharing a common ancestor, the differences in the structural properties of the resident tissues affect cell behavior and prime them to react differently to stimuli. Similarly to the bone marrow, the cortical portion of the bone contains a unique subset of cells that stains positively for the common MSC-associated markers. These cells display different multipotent differentiation capability, clonogenic expansion, and immunosuppressive potential. In particular, when compared with BM-MSC, CBF-MSC are bigger in size, show a lower proliferation rate at early passages, have a greater commitment toward the osteogenic lineage, constitutively produce nitric oxide as a mediator for bone remodeling, and more readily respond to proinflammatory cytokines. Our data suggest that the effect of the tissue's microenvironment makes the CBF-MSC a superior candidate in the development of new strategies for bone repair.

  4. Tuning cell fate

    PubMed Central

    Kami, Daisuke; Gojo, Satoshi

    2014-01-01

    Epigenetic interventions are required to induce reprogramming from one cell type to another. At present, various cellular reprogramming methods such as somatic cell nuclear transfer, cell fusion, and direct reprogramming using transcription factors have been reported. In particular, direct reprogramming from somatic cells to induced pluripotent stem cells (iPSCs) has been achieved using defined factors that play important epigenetic roles. Although the mechanisms underlying cellular reprogramming and vertebrate regeneration, including appendage regeneration, remain unknown, dedifferentiation occurs at an early phase in both the events, and both events are contrasting with regard to cell death. We compared the current status of changes in cell fate of iPSCs with that of vertebrate regeneration and suggested that substantial insights into vertebrate regeneration should be helpful for safe applications of iPSCs to medicine. PMID:24736602

  5. Heparin affects human bone marrow stromal cell fate: Promoting osteogenic and reducing adipogenic differentiation and conversion.

    PubMed

    Simann, Meike; Schneider, Verena; Le Blanc, Solange; Dotterweich, Julia; Zehe, Viola; Krug, Melanie; Jakob, Franz; Schilling, Tatjana; Schütze, Norbert

    2015-09-01

    Heparins are broadly used for the prevention and treatment of thrombosis and embolism. Yet, osteoporosis is considered to be a severe side effect in up to one third of all patients on long-term treatment. However, the mechanisms underlying this clinical problem are only partially understood. To investigate if heparin affects differentiation of skeletal precursors, we examined the effects of heparin on the osteogenic and adipogenic lineage commitment and differentiation of primary human bone marrow stromal cells (hBMSCs). Due to the known inverse relationship between adipogenesis and osteogenesis and the capacity of pre-differentiated cells to convert into the respective other lineage, we also determined heparin effects on osteogenic conversion and adipogenic differentiation/conversion. Interestingly, heparin did not only significantly increase mRNA expression and enzyme activity of the osteogenic marker alkaline phosphatase (ALP), but it also promoted mineralization during osteogenic differentiation and conversion. Furthermore, the mRNA expression of the osteogenic marker bone morphogenic protein 4 (BMP4) was enhanced. In addition, heparin administration partly prevented adipogenic differentiation and conversion demonstrated by reduced lipid droplet formation along with a decreased expression of adipogenic markers. Moreover, luciferase reporter assays, inhibitor experiments and gene expression analyses revealed that heparin had putative permissive effects on osteogenic signaling via the BMP pathway and reduced the mRNA expression of the Wnt pathway inhibitors dickkopf 1 (DKK1) and sclerostin (SOST). Taken together, our data show a rather supportive than inhibitory effect of heparin on osteogenic hBMSC differentiation and conversion in vitro. Further studies will have to investigate the net effects of heparin administration on bone formation versus bone resorption in vivo to unravel the molecular mechanisms of heparin-associated osteoporosis and reconcile

  6. Caenorhabditis elegans vulval cell fate patterning

    NASA Astrophysics Data System (ADS)

    Félix, Marie-Anne

    2012-08-01

    The spatial patterning of three cell fates in a row of competent cells is exemplified by vulva development in the nematode Caenorhabditis elegans. The intercellular signaling network that underlies fate specification is well understood, yet quantitative aspects remain to be elucidated. Quantitative models of the network allow us to test the effect of parameter variation on the cell fate pattern output. Among the parameter sets that allow us to reach the wild-type pattern, two general developmental patterning mechanisms of the three fates can be found: sequential inductions and morphogen-based induction, the former being more robust to parameter variation. Experimentally, the vulval cell fate pattern is robust to stochastic and environmental challenges, and minor variants can be detected. The exception is the fate of the anterior cell, P3.p, which is sensitive to stochastic variation and spontaneous mutation, and is also evolving the fastest. Other vulval precursor cell fates can be affected by mutation, yet little natural variation can be found, suggesting stabilizing selection. Despite this fate pattern conservation, different Caenorhabditis species respond differently to perturbations of the system. In the quantitative models, different parameter sets can reconstitute their response to perturbation, suggesting that network variation among Caenorhabditis species may be quantitative. Network rewiring likely occurred at longer evolutionary scales.

  7. SOIL ORGANIC AMENDMENT AS AFFECTING HERBICIDE FATE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The addition of organic amendments or organic wastes to soils have been shown to affect the fate of soil applied herbicides, although it is an issue very seldom considered when making the decision of fertilizing soil or disposing organic wastes. The addition of organic wastes to soils is viewed as v...

  8. Collagen Substrate Stiffness Anisotropy Affects Cellular Elongation, Nuclear Shape, and Stem Cell Fate toward Anisotropic Tissue Lineage.

    PubMed

    Islam, Anowarul; Younesi, Mousa; Mbimba, Thomas; Akkus, Ozan

    2016-09-01

    Rigidity of substrates plays an important role in stem cell fate. Studies are commonly carried out on isotropically stiff substrate or substrates with unidirectional stiffness gradients. However, many native tissues are anisotropically stiff and it is unknown whether controlled presentation of stiff and compliant material axes on the same substrate governs cytoskeletal and nuclear morphology, as well as stem cell differentiation. In this study, electrocompacted collagen sheets are stretched to varying degrees to tune the stiffness anisotropy (SA) in the range of 1 to 8, resulting in stiff and compliant material axes orthogonal to each other. The cytoskeletal aspect ratio increased with increasing SA by about fourfold. Such elongation was absent on cellulose acetate replicas of aligned collagen surfaces indicating that the elongation was not driven by surface topography. Mesenchymal stem cells (MSCs) seeded on varying anisotropy sheets displayed a dose-dependent upregulation of tendon-related markers such as Mohawk and Scleraxis. After 21 d of culture, highly anisotropic sheets induced greater levels of production of type-I, type-III collagen, and thrombospondin-4. Therefore, SA has direct effects on MSC differentiation. These findings may also have ramifications of stem cell fate on other anisotropically stiff tissues, such as skeletal/cardiac muscles, ligaments, and bone.

  9. Collagen Substrate Stiffness Anisotropy Affects Cellular Elongation, Nuclear Shape, and Stem Cell Fate toward Anisotropic Tissue Lineage.

    PubMed

    Islam, Anowarul; Younesi, Mousa; Mbimba, Thomas; Akkus, Ozan

    2016-09-01

    Rigidity of substrates plays an important role in stem cell fate. Studies are commonly carried out on isotropically stiff substrate or substrates with unidirectional stiffness gradients. However, many native tissues are anisotropically stiff and it is unknown whether controlled presentation of stiff and compliant material axes on the same substrate governs cytoskeletal and nuclear morphology, as well as stem cell differentiation. In this study, electrocompacted collagen sheets are stretched to varying degrees to tune the stiffness anisotropy (SA) in the range of 1 to 8, resulting in stiff and compliant material axes orthogonal to each other. The cytoskeletal aspect ratio increased with increasing SA by about fourfold. Such elongation was absent on cellulose acetate replicas of aligned collagen surfaces indicating that the elongation was not driven by surface topography. Mesenchymal stem cells (MSCs) seeded on varying anisotropy sheets displayed a dose-dependent upregulation of tendon-related markers such as Mohawk and Scleraxis. After 21 d of culture, highly anisotropic sheets induced greater levels of production of type-I, type-III collagen, and thrombospondin-4. Therefore, SA has direct effects on MSC differentiation. These findings may also have ramifications of stem cell fate on other anisotropically stiff tissues, such as skeletal/cardiac muscles, ligaments, and bone. PMID:27377355

  10. High t-PA release by neonate brain microvascular endothelial cells under glutamate exposure affects neuronal fate.

    PubMed

    Henry, Vincent Jean; Lecointre, Maryline; Laudenbach, Vincent; Ali, Carine; Macrez, Richard; Jullienne, Amandine; Berezowski, Vincent; Carmeliet, Peter; Vivien, Denis; Marret, Stéphane; Gonzalez, Bruno José; Leroux, Philippe

    2013-02-01

    impact vascular integrity but may also influence neuronal fate, via regulation of apoptosis in immature cells and, as in adult by potentiating glutamate toxicity in mature neurons. The data point out putative implication of microvessels in glutamate neurotoxicity in the development, and justify research towards vessel oriented neuroprotection strategies in neonates.

  11. Mechanotransduction: Tuning Stem Cells Fate

    PubMed Central

    D'Angelo, Francesco; Tiribuzi, Roberto; Armentano, Ilaria; Kenny, Josè Maria; Martino, Sabata; Orlacchio, Aldo

    2011-01-01

    It is a general concern that the success of regenerative medicine-based applications is based on the ability to recapitulate the molecular events that allow stem cells to repair the damaged tissue/organ. To this end biomaterials are designed to display properties that, in a precise and physiological-like fashion, could drive stem cell fate both in vitro and in vivo. The rationale is that stem cells are highly sensitive to forces and that they may convert mechanical stimuli into a chemical response. In this review, we describe novelties on stem cells and biomaterials interactions with more focus on the implication of the mechanical stimulation named mechanotransduction. PMID:24956164

  12. Loss of Ptf1a Leads to a Widespread Cell-Fate Misspecification in the Brainstem, Affecting the Development of Somatosensory and Viscerosensory Nuclei

    PubMed Central

    Iskusnykh, Igor Y.; Steshina, Ekaterina Y.

    2016-01-01

    The brainstem contains diverse neuronal populations that regulate a wide range of processes vital to the organism. Proper cell-fate specification decisions are critical to achieve neuronal diversity in the CNS, but the mechanisms regulating cell-fate specification in the developing brainstem are poorly understood. Previously, it has been shown that basic helix-loop-helix transcription factor Ptf1a is required for the differentiation and survival of neurons of the inferior olivary and cochlear brainstem nuclei, which contribute to motor coordination and sound processing, respectively. In this study, we show that the loss of Ptf1a compromises the development of the nucleus of the solitary tract, which processes viscerosensory information, and the spinal and principal trigeminal nuclei, which integrate somatosensory information of the face. Combining genetic fate-mapping, birth-dating, and gene expression studies, we found that at least a subset of brainstem abnormalities in Ptf1a−/− mice are mediated by a dramatic cell-fate misspecification in rhombomeres 2–7, which results in the production of supernumerary viscerosensory and somatosensory neurons of the Lmx1b lineage at the expense of Pax2+ GABAergic viscerosensory and somatosensory neurons, and inferior olivary neurons. Our data identify Ptf1a as a major regulator of cell-fate specification decisions in the developing brainstem, and as a previously unrecognized developmental regulator of both viscerosensory and somatosensory brainstem nuclei. SIGNIFICANCE STATEMENT Cell-fate specification decisions are critical for normal CNS development. Although extensively studied in the cerebellum and spinal cord, the mechanisms mediating cell-fate decisions in the brainstem, which regulates a wide range of processes vital to the organism, remain largely unknown. Here we identified mouse Ptf1a as a novel regulator of cell-fate decisions during both early and late brainstem neurogenesis, which are critical for proper

  13. Stem Cell Fate Is a Touchy Subject.

    PubMed

    Smith, Quinton; Gerecht, Sharon

    2016-09-01

    Uncoupling synergistic interactions between physio-chemical cues that guide stem cell fate may improve efforts to direct their differentiation in culture. Using supramolecular hydrogels, Alakpa et al. (2016) demonstrate that mesenchymal stem cell differentiation is paired to depletion of bioactive metabolites, which can be utilized to chemically induce osteoblast and chondrocyte fate. PMID:27588745

  14. Cell Fate Decision Making through Oriented Cell Division

    PubMed Central

    Johnston, Christopher A.

    2016-01-01

    The ability to dictate cell fate decisions is critical during animal development. Moreover, faithful execution of this process ensures proper tissue homeostasis throughout adulthood, whereas defects in the molecular machinery involved may contribute to disease. Evolutionarily conserved protein complexes control cell fate decisions across diverse tissues. Maintaining proper daughter cell inheritance patterns of these determinants during mitosis is therefore a fundamental step of the cell fate decision-making process. In this review, we will discuss two key aspects of this fate determinant segregation activity, cortical cell polarity and mitotic spindle orientation, and how they operate together to produce oriented cell divisions that ultimately influence daughter cell fate. Our focus will be directed at the principal underlying molecular mechanisms and the specific cell fate decisions they have been shown to control. PMID:26844213

  15. Asymmetric cell division during T cell development controls downstream fate

    PubMed Central

    Pham, Kim; Shimoni, Raz; Charnley, Mirren; Ludford-Menting, Mandy J.; Hawkins, Edwin D.; Ramsbottom, Kelly; Oliaro, Jane; Izon, David; Ting, Stephen B.; Reynolds, Joseph; Lythe, Grant; Molina-Paris, Carmen; Melichar, Heather; Robey, Ellen; Humbert, Patrick O.; Gu, Min

    2015-01-01

    During mammalian T cell development, the requirement for expansion of many individual T cell clones, rather than merely expansion of the entire T cell population, suggests a possible role for asymmetric cell division (ACD). We show that ACD of developing T cells controls cell fate through differential inheritance of cell fate determinants Numb and α-Adaptin. ACD occurs specifically during the β-selection stage of T cell development, and subsequent divisions are predominantly symmetric. ACD is controlled by interaction with stromal cells and chemokine receptor signaling and uses a conserved network of polarity regulators. The disruption of polarity by deletion of the polarity regulator, Scribble, or the altered inheritance of fate determinants impacts subsequent fate decisions to influence the numbers of DN4 cells arising after the β-selection checkpoint. These findings indicate that ACD enables the thymic microenvironment to orchestrate fate decisions related to differentiation and self-renewal. PMID:26370500

  16. Cell fate determination in the vertebrate retina.

    PubMed Central

    Cepko, C L; Austin, C P; Yang, X; Alexiades, M; Ezzeddine, D

    1996-01-01

    In the vertebrate central nervous system, the retina has been a useful model for studies of cell fate determination. Recent results from studies conducted in vitro and in vivo suggest a model of retinal development in which both the progenitor cells and the environment change over time. The model is based upon the notion that the mitotic cells within the retina change in their response properties, or "competence", during development. These changes presage the ordered appearance of distinct cell types during development and appear to be necessary for the production of the distinct cell types. As the response properties of the cells change, so too do the environmental signals that the cells encounter. Together, intrinsic properties and extrinsic cues direct the choice of cell fate. Images Fig. 2 Fig. 5 PMID:8570600

  17. Specification of germ cell fate in mice.

    PubMed Central

    Saitou, Mitinori; Payer, Bernhard; Lange, Ulrike C; Erhardt, Sylvia; Barton, Sheila C; Surani, M Azim

    2003-01-01

    An early fundamental event during development is the segregation of germ cells from somatic cells. In many organisms, this is accomplished by the inheritance of preformed germ plasm, which apparently imposes transcriptional repression to prevent somatic cell fate. However, in mammals, pluripotent epiblast cells acquire germ cell fate in response to signalling molecules. We have used single cell analysis to study how epiblast cells acquire germ cell competence and undergo specification. Germ cell competent cells express Fragilis and initially progress towards a somatic mesodermal fate. However, a subset of these cells, the future primordial germ cells (PGCs), then shows rapid upregulation of Fragilis with concomitant transcriptional repression of a number of genes, including Hox and Smad genes. This repression may be a key event associated with germ cell specification. Furthermore, PGCs express Stella and other genes, such as Oct-4 that are associated with pluripotency. While these molecules are also detected in mature oocytes as maternally inherited factors, their early role is to regulate development and maintain pluripotency, and they do not serve the role of classical germline determinants. PMID:14511483

  18. Lhx6 and Lhx8: cell fate regulators and beyond

    PubMed Central

    Zhou, Chen; Yang, Guodong; Chen, Mo; He, Ling; Xiang, Lusai; Ricupero, Christopher; Mao, Jeremy J.; Ling, Junqi

    2015-01-01

    As transcription factors of the lines (LIN)-11/Islet (Isl)-1/mitosis entry checkpoint (MEC)-3 (LIM)-homeobox subfamily, LIM homeobox (Lhx)6 and -8 are remarkably conserved and involved in the morphogenesis of multiple organ systems. Lhx6 and -8 play overlapping and distinctive roles, but in general act as cell fate mediators and in turn are regulated by several transcriptional factors, such as sonic hedgehog, fibroblast growth factors, and wingless-int (Wnt)/β-catenin. In this review, we first summarize Lhx6 and -8 distributions in development and then explore how Lhx6 and -8 act as transcription factors and coregulators of cell lineage specification. Known Lhx6 and -8 functions and targets are outlined in neurogenesis, craniofacial development, and germ cell differentiation. The underlying mechanisms of Lhx6 and -8 in regulating cell fate remain elusive. Whether Lhx6 and -8 affect functions in tissues and organs other than neural, craniofacial, oocytes, and germ cells is largely unexplored. Taken together, Lhx6 and -8 are important regulators of cell lineage specification and may act as one of the pivotal mediators of stem cell fate. Undoubtedly, future investigations of Lhx6 and -8 biology will continue to yield fascinating insights into tissue development and homeostasis, in addition to their putative roles in tissue regeneration and ageing.—Zhou, C., Yang, G., Chen, M., He, L., Xiang, L., Ricupero, C., Mao, J. J., Ling, J. Lhx6 and Lhx8: cell fate regulators and beyond. PMID:26148970

  19. Hippo Pathway Activity Influences Liver Cell Fate

    PubMed Central

    Yimlamai, Dean; Christodoulou, Constantina; Galli, Giorgio G.; Yanger, Kilangsungla; Pepe-Mooney, Brian; Gurung, Basanta; Shrestha, Kriti; Cahan, Patrick; Stanger, Ben Z.; Camargo, Fernando D.

    2014-01-01

    The Hippo signaling pathway is an important regulator of cellular proliferation and organ size. However, little is known about the role of this cascade in the control of cell fate. Employing a combination of lineage tracing, clonal analysis, and organoid culture approaches, we demonstrate that Hippo-pathway activity is essential for the maintenance of the differentiated hepatocyte state. Remarkably, acute inactivation of Hippo-pathway signaling in vivo is sufficient to de-differentiate, at very high efficiencies, adult hepatocytes into cells bearing progenitor characteristics. These hepatocyte-derived progenitor cells demonstrate self-renewal and engraftment capacity at the single cell level. We also identify the NOTCH signaling pathway as a functional important effector downstream of the Hippo transducer YAP. Our findings uncover a potent role for Hippo/YAP signaling in controlling liver cell fate, and reveal an unprecedented level of phenotypic plasticity in mature hepatocytes, which has implications for the understanding and manipulation of liver regeneration. PMID:24906150

  20. Specifying and protecting germ cell fate

    PubMed Central

    Strome, Susan; Updike, Dustin

    2015-01-01

    Germ cells are the special cells in the body that undergo meiosis to generate gametes and subsequently entire new organisms after fertilization, a process that continues generation after generation. Recent studies have expanded our understanding of the factors and mechanisms that specify germ cell fate, including the partitioning of maternally supplied ‘germ plasm’, inheritance of epigenetic memory and expression of transcription factors crucial for primordial germ cell (PGC) development. Even after PGCs are specified, germline fate is labile and thus requires protective mechanisms, such as global transcriptional repression, chromatin state alteration and translation of only germline-appropriate transcripts. Findings from diverse species continue to provide insights into the shared and divergent needs of these special reproductive cells. PMID:26122616

  1. Photoreceptor cell fate specification in vertebrates

    PubMed Central

    Brzezinski, Joseph A.; Reh, Thomas A.

    2015-01-01

    Photoreceptors – the light-sensitive cells in the vertebrate retina – have been extremely well-characterized with regards to their biochemistry, cell biology and physiology. They therefore provide an excellent model for exploring the factors and mechanisms that drive neural progenitors into a differentiated cell fate in the nervous system. As a result, great progress in understanding the transcriptional network that controls photoreceptor specification and differentiation has been made over the last 20 years. This progress has also enabled the production of photoreceptors from pluripotent stem cells, thereby aiding the development of regenerative medical approaches to eye disease. In this Review, we outline the signaling and transcription factors that drive vertebrate photoreceptor development and discuss how these function together in gene regulatory networks to control photoreceptor cell fate specification. PMID:26443631

  2. Gene expression dynamics during cell differentiation: Cell fates as attractors and cell fate decisions as bifurcations

    NASA Astrophysics Data System (ADS)

    Huang, Sui

    2006-03-01

    During development of multicellular organisms, multipotent stem and progenitor cells undergo a series of hierarchically organized ``somatic speciation'' processes consisting of binary branching events to achieve the diversity of discretely distinct differentiated cell types in the body. Current paradigms of genetic regulation of development do not explain this discreteness, nor the time-irreversibility of differentiation. Each cell contains the same genome with the same N (˜ 25,000) genes and each cell type k is characterized by a distinct stable gene activation pattern, expressed as the cell state vector Sk(t) = xk1(t) ,.. xki(t),.. xkN(t), where xki is the activation state of gene i in cell type k. Because genes are engaged in a network of mutual regulatory interactions, the movement of Sk(t) in the N-dimensional state space is highly constrained and the organism can only realize a tiny fraction of all possible configurations Sk. Then, the trajectories of Sk reflect the diversifying developmental paths and the mature cell types are high-dimensional attractor states. Experimental results based on gene expression profile measurements during blood cell differentiation using DNA microarrays are presented that support the old idea that cell types are attractors. This basic notion is extended to treat binary fate decisions as bifurcations in the dynamics of networks circuits. Specifically, during cell fate decision, the metastable progenitor attractor is destabilized, poising the cell on a `watershed state' so that it can stochastically or in response to deterministic perturbations enter either one of two alternative fates. Overall, the model and supporting experimental data provide an overarching conceptual framework that helps explain how the specifics of gene network architecture produces discreteness and robustness of cell types, allows for both stochastic and deterministic cell fate decision and ensures directionality of organismal development.

  3. Connecting Mitochondria, Metabolism, and Stem Cell Fate

    PubMed Central

    Wanet, Anaïs; Arnould, Thierry; Najimi, Mustapha

    2015-01-01

    As sites of cellular respiration and energy production, mitochondria play a central role in cell metabolism. Cell differentiation is associated with an increase in mitochondrial content and activity and with a metabolic shift toward increased oxidative phosphorylation activity. The opposite occurs during reprogramming of somatic cells into induced pluripotent stem cells. Studies have provided evidence of mitochondrial and metabolic changes during the differentiation of both embryonic and somatic (or adult) stem cells (SSCs), such as hematopoietic stem cells, mesenchymal stem cells, and tissue-specific progenitor cells. We thus propose to consider those mitochondrial and metabolic changes as hallmarks of differentiation processes. We review how mitochondrial biogenesis, dynamics, and function are directly involved in embryonic and SSC differentiation and how metabolic and sensing pathways connect mitochondria and metabolism with cell fate and pluripotency. Understanding the basis of the crosstalk between mitochondria and cell fate is of critical importance, given the promising application of stem cells in regenerative medicine. In addition to the development of novel strategies to improve the in vitro lineage-directed differentiation of stem cells, understanding the molecular basis of this interplay could lead to the identification of novel targets to improve the treatment of degenerative diseases. PMID:26134242

  4. Connecting Mitochondria, Metabolism, and Stem Cell Fate.

    PubMed

    Wanet, Anaïs; Arnould, Thierry; Najimi, Mustapha; Renard, Patricia

    2015-09-01

    As sites of cellular respiration and energy production, mitochondria play a central role in cell metabolism. Cell differentiation is associated with an increase in mitochondrial content and activity and with a metabolic shift toward increased oxidative phosphorylation activity. The opposite occurs during reprogramming of somatic cells into induced pluripotent stem cells. Studies have provided evidence of mitochondrial and metabolic changes during the differentiation of both embryonic and somatic (or adult) stem cells (SSCs), such as hematopoietic stem cells, mesenchymal stem cells, and tissue-specific progenitor cells. We thus propose to consider those mitochondrial and metabolic changes as hallmarks of differentiation processes. We review how mitochondrial biogenesis, dynamics, and function are directly involved in embryonic and SSC differentiation and how metabolic and sensing pathways connect mitochondria and metabolism with cell fate and pluripotency. Understanding the basis of the crosstalk between mitochondria and cell fate is of critical importance, given the promising application of stem cells in regenerative medicine. In addition to the development of novel strategies to improve the in vitro lineage-directed differentiation of stem cells, understanding the molecular basis of this interplay could lead to the identification of novel targets to improve the treatment of degenerative diseases.

  5. Transgenerational cell fate profiling: a method for the graphical presentation of complex cell cycle alterations.

    PubMed

    Jemaà, Mohamed; Galluzzi, Lorenzo; Kepp, Oliver; Castedo, Maria; Rello-Varona, Santiago; Vitale, Ilio; Kroemer, Guido

    2013-01-01

    The illicit generation of tetraploid cells constitutes a prominent driver of oncogenesis, as it often precedes the development of aneuploidy and genomic instability. In addition, tetraploid (pre-)malignant cells display an elevated resistance against radio- and chemotherapy. Here, we report a strategy to preferentially kill tetraploid tumor cells based on the broad-spectrum kinase inhibitor SP600125. Live videomicroscopy revealed that SP600125 affects the execution of mitosis, impedes proper cell division and/or activates apoptosis in near-to-tetraploid, though less so in parental, cancer cells. We propose a novel graphical model to quantify the differential response of diploid and tetraploid cells to mitotic perturbators, including SP600125, which we baptized "transgenerational cell fate profiling." We speculate that this representation constitutes a valid alternative to classical "single-cell fate" and "genealogical" profiling and, hence, may facilitate the analysis of cell fate within a heterogeneous population as well as the visual examination of cell cycle alterations.

  6. Geometric control of myogenic cell fate

    PubMed Central

    de Juan-Pardo, Elena M; Hoang, Mike Bao-Trong; Conboy, Irina M

    2006-01-01

    This work combines expertise in stem cell biology and bioengineering to define the system for geometric control of proliferation and differentiation of myogenic progenitor cells. We have created an artificial niche of myogenic progenitor cells, namely, modified extracellular matrix (ECM) substrates with spatially embedded growth or differentiation factors (GF, DF) that predictably direct muscle cell fate in a geometric pattern. Embedded GF and DF signal progenitor cells from specifically defined areas on the ECM successfully competed against culture media for myogenic cell fate determination at a clearly defined boundary. Differentiation of myoblasts into myotubes is induced in growth-promoting medium, myotube formation is delayed in differentiation-promoting medium, and myogenic cells, at different stages of proliferation and differentiation, can be induced to coexist adjacently in identical culture media. This method can be used to identify molecular interactions between cells in different stages of myogenic differentiation, which are likely to be important determinants of tissue repair. The designed ECM niches can be further developed into a vehicle for transplantation of myogenic progenitor cells maintaining their regenerative potential. Additionally, this work may also serve as a general model to engineer synthetic cellular niches to harness the regenerative potential of organ stem cells. PMID:17722537

  7. Patterning and cell fate in ear development.

    PubMed

    Alsina, Berta; Giraldez, Fernando; Pujades, Cristina

    2009-01-01

    The inner ear is a complex structure responsible for the senses of audition and balance in vertebrates. The ear is organised into different sense organs that are specialised to detect specific stimuli such as sound and linear or angular accelerations. The elementary sensory unit of the ear consists of hair cells, supporting cells, neurons and Schwann cells. Hair cells are the mechano-electrical transducing elements, and otic neurons convey information coded in electrical impulses to the brain. With the exception of the Schwann cells, all cellular elements of the inner ear derive from the otic placode. This is an ectodermal thickening that is specified in the head ectoderm adjacent to the caudal hindbrain. The complex organisation of the ear requires precise coupling of regional specification and cell fate decisions during development, i.e. specificity in defining particular spatial domains containing particular cell types. Those decisions are taken early in development and are the subject of this article. We review here recent work on: i) early patterning of the otic placode, ii) the role of neural tube signals in the patterning of the otic vesicle, and iii) the genes underlying cell fate determination of neurons and sensory hair cells.

  8. Fibronectin mediates mesendodermal cell fate decisions

    PubMed Central

    Cheng, Paul; Andersen, Peter; Hassel, David; Kaynak, Bogac L.; Limphong, Pattraranee; Juergensen, Lonny; Kwon, Chulan; Srivastava, Deepak

    2013-01-01

    Non-cell-autonomous signals often play crucial roles in cell fate decisions during animal development. Reciprocal signaling between endoderm and mesoderm is vital for embryonic development, yet the key signals and mechanisms remain unclear. Here, we show that endodermal cells efficiently promote the emergence of mesodermal cells in the neighboring population through signals containing an essential short-range component. The endoderm-mesoderm interaction promoted precardiac mesoderm formation in mouse embryonic stem cells and involved endodermal production of fibronectin. In vivo, fibronectin deficiency resulted in a dramatic reduction of mesoderm accompanied by endodermal expansion in zebrafish embryos. This event was mediated by regulation of Wnt signaling in mesodermal cells through activation of integrin-β1. Our findings highlight the importance of the extracellular matrix in mediating short-range signals and reveal a novel function of endoderm, involving fibronectin and its downstream signaling cascades, in promoting the emergence of mesoderm. PMID:23715551

  9. Autophagy: controlling cell fate in rheumatic diseases.

    PubMed

    Rockel, Jason S; Kapoor, Mohit

    2016-09-01

    Autophagy, an endogenous process necessary for the turnover of organelles, maintains cellular homeostasis and directs cell fate. Alterations to the regulation of autophagy contribute to the progression of various rheumatic diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), osteoarthritis (OA) and systemic sclerosis (SSc). Implicit in the progression of these diseases are cell-type-specific responses to surrounding factors that alter autophagy: chondrocytes within articular cartilage show decreased autophagy in OA, leading to rapid cell death and cartilage degeneration; fibroblasts from patients with SSc have restricted autophagy, similar to that seen in aged dermal fibroblasts; fibroblast-like synoviocytes from RA joints show altered autophagy, which contributes to synovial hyperplasia; and dysregulation of autophagy in haematopoietic lineage cells alters their function and maturation in SLE. Various upstream mechanisms also contribute to these diseases by regulating autophagy as part of their signalling cascades. In this Review, we discuss the links between autophagy, immune responses, fibrosis and cellular fates as they relate to pathologies associated with rheumatic diseases. Therapies in clinical use, and in preclinical or clinical development, are also discussed in relation to their effects on autophagy in rheumatic diseases. PMID:27334205

  10. Riboflavin in development and cell fate.

    PubMed

    Powers, Hilary J; Corfe, B M; Nakano, E

    2012-01-01

    Riboflavin (7,8-dimethyl-10-ribitylisoalloxazine; vitamin B2) is a water-soluble vitamin, cofactor derivatives of which (FAD, FMN) act as electron acceptors in the oxidative metabolism of carbohydrate, amino acids and fatty acids and which in the reduced state can donate electrons to complex II of the electron transport chain. This means that riboflavin is essential for energy generation in the aerobic cell, through oxidative phosphorylation. The classic effects of riboflavin deficiency on growth and development have generally been explained in terms of these functions. However, research also suggests that riboflavin may have specific functions associated with cell fate determination, which would have implications for growth and development. In particular, riboflavin depletion interferes with the normal progression of the cell cycle, probably through effects on the expression of regulatory genes, exerted at both the transcriptional and proteomic level.

  11. Bifurcation dynamics and determination of alternate cell fates in bipotent progenitor cells.

    PubMed

    Li, Shanshan; Liu, Yanwei; Liu, Zengrong; Wang, Ruiqi

    2015-04-01

    The gene regulatory networks in which two lineage-affiliated transcription factors, such as GATA1 and PU.1, inhibit each other but activate themselves so as to regulate the choice between alternative cell fates have been extensively studied. These simple networks can generate bistability and explain the transitions between the alternative cell fates. The commitment of a progenitor cell to a new fate corresponds to the occurrence of different types of bifurcations, depending on if a system is symmetrical and how perturbations affect the system. Here we take a general modeling and analyzing approach and show that the lateral inhibition with symmetry and asymmetry can lead to different bifurcation dynamics. Especially, if cell fate decision-making is initiated with asymmetry or symmetry-breaking perturbations, a progenitor cell pre-patterns itself into a polarized cell, depending on the asymmetry or symmetry-breaking perturbations. This study may help us understand the fundamental features of binary cell fate decisions more clearly and further apply to a wider range of decision-making processes.

  12. Engineering the human pluripotent stem cell microenvironment to direct cell fate

    PubMed Central

    Hazeltine, Laurie B.; Selekman, Joshua A.; Palecek, Sean P.

    2013-01-01

    Human pluripotent stem cells (hPSCs), including both embryonic stem cells and induced pluripotent stem cells, offer a potential cell source for research, drug screening, and regenerative medicine applications due to their unique ability to self-renew or differentiate to any somatic cell type. Before the full potential of hPSCs can be realized, robust protocols must be developed to direct their fate. Cell fate decisions are based on components of the surrounding microenvironment, including soluble factors, substrate or extracellular matrix, cell-cell interactions, mechanical forces, and 2D or 3D architecture. Depending on their spatio-temporal context, these components can signal hPSCs to either self-renew or differentiate to cell types of the ectoderm, mesoderm, or endoderm. Researchers working at the interface of engineering and biology have identified various factors which can affect hPSC fate, often based on lessons from embryonic development, and they have utilized this information to design in vitro niches which can reproducibly direct hPSC fate. This review highlights culture systems that have been engineered to promote self-renewal or differentiation of hPSCs, with a focus on studies that have elucidated the contributions of specific microenvironmental cues in the context of those culture systems. We propose the use of microsystems technologies for high-throughput screening of spatial-temporal presentation of cues, as this has been demonstrated to be a powerful approach for differentiating hPSCs to desired cell types. PMID:23510904

  13. Combining insoluble and soluble factors to steer stem cell fate

    NASA Astrophysics Data System (ADS)

    Dingal, P. C. Dave P.; Discher, Dennis E.

    2014-06-01

    Materials-based control of stem cell fate is beginning to be rigorously combined with traditional soluble-factor approaches to better understand the cells' behaviour and maximize their potential for therapy.

  14. Proliferating cell nuclear antigen in neutrophil fate.

    PubMed

    Witko-Sarsat, Véronique; Ohayon, Delphine

    2016-09-01

    The life span of a neutrophil is a tightly regulated process as extended survival is beneficial for pathogen elimination and cell death necessary to prevent cytotoxic content release from activated neutrophils at the inflammatory site. Therefore, the control between survival and death must be a dynamic process. We have previously described that proliferating cell nuclear antigen (PCNA) which is known as a nuclear protein pivotal in DNA synthesis, is a key element in controlling neutrophil survival through its association with procaspases. Contrary to the dogma which asserted that PCNA has a strictly nuclear function, in mature neutrophils, PCNA is present exclusively within the cytosol due to its nuclear export at the end of the granulocytic differentiation. More recent studies are consistent with the notion that the cytosolic scaffold of PCNA is aimed at modulating neutrophil fate rather than simply preventing death. Ultimately, targeting neutrophil survival might have important applications not just in the field of immunology and inflammation, but also in hematology and transfusion. The neutrophil emerges as a unique and powerful cellular model to unravel the basic mechanisms governing the cell cycle-independent functions of PCNA and should be considered as a leader of the pack. PMID:27558345

  15. Linking the Cell Cycle to Cell Fate Decisions.

    PubMed

    Dalton, Stephen

    2015-10-01

    Pluripotent stem cells (PSCs) retain the ability to differentiate into a wide range of cell types while undergoing self-renewal. They also exhibit an unusual mode of cell cycle regulation, reflected by a cell cycle structure where G1 and G2 phases are truncated. When individual PSCs are exposed to specification cues, they activate developmental programs and remodel the cell cycle so that the length of G1 and overall cell division times increase. The response of individual stem cells to pro-differentiation signals is strikingly heterogeneous, resulting in asynchronous differentiation. Recent evidence indicates that this phenomenon is due to cell cycle-dependent mechanisms that restrict the initial activation of developmental genes to the G1 phase. This suggests a broad biological mechanism where multipotent cells are 'primed' to initiate cell fate decisions during their transition through G1. Here, I discuss mechanisms underpinning the commitment towards the differentiated state and its relation to the cell cycle.

  16. Cell fate control in the developing central nervous system

    SciTech Connect

    Guérout, Nicolas; Li, Xiaofei; Barnabé-Heider, Fanie

    2014-02-01

    The principal neural cell types forming the mature central nervous system (CNS) are now understood to be diverse. This cellular subtype diversity originates to a large extent from the specification of the earlier proliferating progenitor populations during development. Here, we review the processes governing the differentiation of a common neuroepithelial cell progenitor pool into mature neurons, astrocytes, oligodendrocytes, ependymal cells and adult stem cells. We focus on studies performed in mice and involving two distinct CNS structures: the spinal cord and the cerebral cortex. Understanding the origin, specification and developmental regulators of neural cells will ultimately impact comprehension and treatments of neurological disorders and diseases. - Highlights: • Similar mechanisms regulate cell fate in different CNS cell types and structures. • Cell fate regulators operate in a spatial–temporal manner. • Different neural cell types rely on the generation of a diversity of progenitor cells. • Cell fate decision is dictated by the integration of intrinsic and extrinsic signals.

  17. Spatial control of adult stem cell fate using nanotopographic cues

    PubMed Central

    An, Steven S.; Afzal, Junaid; Lee, Suengwon; Kwak, Moonkyu; Suh, Kahp-Yang; Levchenko, Andre

    2015-01-01

    Adult stem cells hold great promise as a source of diverse terminally differentiated cell types for tissue engineering applications. However, due to the complexity of chemical and mechanical cues specifying differentiation outcomes, development of arbitrarily complex geometric and structural arrangements of cells, adopting multiple fates from the same initial stem cell population, has been difficult. Here, we show that the topography of the cell adhesion substratum can be an instructive cue to adult stem cells and topographical variations can strongly bias the differentiation outcome of the cells towards adipocyte or osteocyte fates. Switches in cell fate decision from adipogenic to osteogenic lineages were accompanied by changes in cytoskeletal stiffness, spanning a considerable range in the cell softness/rigidity spectrum. Our findings suggest that human mesenchymal stem cells (hMSC) can respond to the varying density of nanotopographical cues by regulating their internal cytoskeletal network and use these mechanical changes to guide them toward making cell fate decisions. We used this finding to design a complex two-dimensional pattern of co-localized cells preferentially adopting two alternative fates, thus paving the road for designing and building more complex tissue constructs with diverse biomedical applications. PMID:24388388

  18. Identifying gene expression modules that define human cell fates.

    PubMed

    Germanguz, I; Listgarten, J; Cinkornpumin, J; Solomon, A; Gaeta, X; Lowry, W E

    2016-05-01

    Using a compendium of cell-state-specific gene expression data, we identified genes that uniquely define cell states, including those thought to represent various developmental stages. Our analysis sheds light on human cell fate through the identification of core genes that are altered over several developmental milestones, and across regional specification. Here we present cell-type specific gene expression data for 17 distinct cell states and demonstrate that these modules of genes can in fact define cell fate. Lastly, we introduce a web-based database to disseminate the results.

  19. Exploration of physical and chemical cues on retinal cell fate.

    PubMed

    Zalis, Marina Castro; Johansson, Sebastian; Johansson, Fredrik; Johansson, Ulrica Englund

    2016-09-01

    Identification of the key components in the physical and chemical milieu directing donor cells into a desired phenotype is a requirement in the investigation of bioscaffolds for the advancement of cell-based therapies for retinal neurodegeneration. We explore the effect of electrospun poly-ε-caprolactone (PCL) fiber scaffold topography and functionalization and culture medium, on the behavior of mouse retinal cells. Dissociated mouse retinal post-natal cells were seeded on random or aligned oriented fibers, with or without laminin coating and cultured with either basic or neurotrophins enriched medium for 7days. Addition of laminin in combination with neurotrophins clearly promoted cell- morphology, fate, and neurite extension. Nanotopography per se significantly affected cell morphology, with mainly bipolar profiles on aligned fibers and more multipolar profiles on random fibers. Laminin induced a remarkable 90° switch of neurite orientation. Herewith, we demonstrate that the chemical cue is stronger than the physical cue for the orientation of retinal neurites and describe the requirement of both neurotrophins and extracellular matrix proteins for extended neurite outgrowth and formation of complex retinal neuronal networks. Therefore, tailor-made PCL fiber mats, which can be physically and chemically modified, indeed influence cell behavior and hence motivate further retinal restorative studies using this system. PMID:27497842

  20. Switching cell fates in the developing Drosophila eye.

    PubMed

    Mavromatakis, Yannis Emmanuel; Tomlinson, Andrew

    2013-11-01

    The developing Drosophila ommatidium is characterized by two distinct waves of pattern formation. In the first wave, a precluster of five cells is formed by a complex cellular interaction mechanism. In the second wave, cells are systematically recruited to the cluster and directed to their fates by developmental cues presented by differentiating precluster cells. These developmental cues are mediated through the receptor tyrosine kinase (RTK) and Notch (N) signaling pathways and their combined activities are crucial in specifying cell type. The transcription factor Lozenge (Lz) is expressed exclusively in second wave cells. Here, we ectopically supply Lz to precluster cells and concomitantly supply the various RTK/N codes that specify each of three second wave cell fates. We thereby reproduce molecular markers of each of the second wave cell types in precluster cells and draw three inferences. First, we confirm that Lz provides key intrinsic information to second wave cells. We can now combine this with the RTK/N signaling to provide a cell fate specification code that entails both extrinsic and intrinsic information. Second, the reproduction of each second wave cell type in the precluster confirms the accuracy of the RTK/N signaling code. Third, RTK/N signaling and Lz need only be presented to the cells for a short period of time in order to specify their fate. PMID:24067351

  1. The Genetic Regulation of Cell Fate During Preimplantation Mouse Development.

    PubMed

    Lokken, A A; Ralston, A

    2016-01-01

    The adult body is estimated to contain several hundred distinct cell types, each with a specialized physiological function. Failure to maintain cell fate can lead to devastating diseases and cancer, but understanding how cell fates are assigned and maintained during animal development provides new opportunities for human health intervention. The mouse is a premier model for evaluating the genetic regulation of cell fate during development because of the wide variety of tools for measuring and manipulating gene expression levels, the ability to access embryos at desired developmental stages, and the similarities between mouse and human development, particularly during the early stages of development. During the first 3 days of mouse development, the preimplantation embryo sets aside cells that will contribute to the extraembryonic tissues. The extraembryonic tissues are essential for establishing pregnancy and ensuring normal fetal development in both mice and humans. Genetic analyses of mouse preimplantation development have permitted identification of genes that are essential for specification of the extraembryonic lineages. In this chapter, we review the tools and concepts of mouse preimplantation development. We describe genes that are essential for cell fate specification during preimplantation stages, and we describe diverse models proposed to account for the mechanisms of cell fate specification during early development. PMID:27475852

  2. Specification of epidermal cell fate in plant shoots.

    PubMed

    Takada, Shinobu; Iida, Hiroyuki

    2014-01-01

    Land plants have evolved a single layer of epidermal cells, which are characterized by mostly anticlinal cell division patterns, formation of a waterproof coat called cuticle, and unique cell types such as stomatal guard cells and trichomes. The shoot epidermis plays important roles not only to protect plants from dehydration and pathogens but also to ensure their proper organogenesis and growth control. Extensive molecular genetic studies in Arabidopsis and maize have identified a number of genes that are required for epidermal cell differentiation. However, the mechanism that specifies shoot epidermal cell fate during plant organogenesis remains largely unknown. Particularly, little is known regarding positional information that should restrict epidermal cell fate to the outermost cell layer of the developing organs. Recent studies suggested that certain members of the HD-ZIP class IV homeobox genes are possible master regulators of shoot epidermal cell fate. Here, we summarize the roles of the regulatory genes that are involved in epidermal cell fate specification and discuss the possible mechanisms that limit the expression and/or activity of the master transcriptional regulators to the outermost cell layer in plant shoots. PMID:24616724

  3. Cell fate determination by ubiquitin-dependent regulation of translation

    PubMed Central

    Werner, Achim; Iwasaki, Shintaro; McGourty, Colleen; Medina-Ruiz, Sofia; Teerikorpi, Nia; Fedrigo, Indro; Ingolia, Nicholas T.; Rape, Michael

    2015-01-01

    Metazoan development depends on accurate execution of differentiation programs that allow pluripotent stem cells to adopt specific fates 1. Differentiation requires changes to chromatin architecture and transcriptional networks, yet whether other regulatory events support cell fate determination is less well understood. Here, we have identified the vertebrate-specific ubiquitin ligase CUL3KBTBD8 as an essential regulator of neural crest specification. CUL3KBTBD8 monoubiquitylates NOLC1 and its paralog TCOF1, whose mutation underlies the neurocristopathy Treacher Collins Syndrome 2,3. Ubiquitylation drives formation of a TCOF1-NOLC1 platform that connects RNA polymerase I with ribosome modification enzymes and remodels the translational program of differentiating cells in favor of neural crest specification. We conclude that ubiquitin-dependent regulation of translation is an important feature of cell fate determination. PMID:26399832

  4. FY08 LDRD Final Report Stem Cell Fate Decisions

    SciTech Connect

    Hiddessen, A

    2009-03-02

    A detailed understanding of the biological control of fate decisions of stem and progenitor cells is needed to harness their full power for tissue repair and/or regeneration. Currently, internal and external factors that regulate stem cell fate are not fully understood. We aim to engineer biocompatible tools to facilitate the measurement and comparison of the roles and significance of immobilized factors such as extracellular matrix and signaling peptides, synergistic and opposing soluble factors and signals, and cell-to-cell communication, in stem cell fate decisions. Our approach is based on the development of cell microarrays to capture viable stem/progenitor cells individually or in small clusters onto substrate-bound signals (e.g. proteins), combined with conventional antibody and customized subcellular markers made in-house, to facilitate tracking of cell behavior during exposure to relevant signals. Below we describe our efforts, including methods to manipulate a model epithelial stem cell system using a custom subcellular reporter to track and measure cell signaling, arrays with surface chemistry that support viable cells and enable controlled presentation of immobilized signals to cells on the array and fluorescence-based measurement of cell response, and successful on-array tests via conventional immunofluorescence assays that indicate correct cell polarity, localization of junctional proteins, and phenotype, properties which are essential to measuring true cell responses.

  5. Metabolism and the Control of Cell Fate Decisions and Stem Cell Renewal

    PubMed Central

    Ito, Kyoko; Ito, Keisuke

    2016-01-01

    Although the stem cells of various tissues remain in the quiescent state to maintain their undifferentiated state, they also undergo cell divisions as required, and if necessary, even a single stem cell is able to provide for lifelong tissue homeostasis. Stem cell populations are precisely controlled by the balance between their symmetric and asymmetric divisions, with their division patterns determined by whether the daughter cells involved retain their self-renewal capacities. Recent studies have reported that metabolic pathways and the distribution of mitochondria are regulators of the division balance of stem cells and that metabolic defects can shift division balance toward symmetric commitment, which leads to stem cell exhaustion. It has also been observed that in asymmetric division, old mitochondria, which are central metabolic organelles, are segregated to the daughter cell fated to cell differentiation, whereas in symmetric division, young and old mitochondria are equally distributed between both daughter cells. Thus, metabolism and mitochondrial biology play important roles in stem cell fate decisions. As these decisions directly affect tissue homeostasis, understanding their regulatory mechanisms in the context of cellular metabolism is critical. PMID:27482603

  6. Regulating functional cell fates in CD8 T cells

    PubMed Central

    Rao, Rajesh; Li, Qingsheng; Kesterson, Joshua; Eppolito, Cheryl; Mischo, Axel; Singhal, Pankaj

    2016-01-01

    The attributes of specificity and memory enable CD8+ T cells to provide long-lasting protection against a variety of challenges. Although, the importance of CD8+ T cells for protection against intracellular infections and transformation is well-established, the functional type; effector phenotypes (Tc1, Tc2, Tc17 and/or Tcreg) and/or memory (effector or central), of CD8+ T cells most desirable for tumor immunity is not established. To determine the tumor efficacy of various effector types and/or memory CD8 T cells, it is imperative to better understand intrinsic and extrinsic factors that regulate CD8+ T cell differentiation and use this information to generate and test distinct functional cell types in tumor models. The focus of our laboratory investigations is to identify the extrinsic factors such as antigen strength, co-stimulatory molecules, cytokines, and small molecule modifiers that regulate intrinsic programs for various effector and/or memory cell fate in antigen specific CD8 T cells. The use of this information to generate immunity in murine tumor models has facilitated development of new adoptive cell transfer (ACT) as well as immunization strategies for cancer treatment. PMID:19859830

  7. Fate and degradation of petroleum hydrocarbons in stormwater bioretention cells

    NASA Astrophysics Data System (ADS)

    LeFevre, Gregory Hallett

    This dissertation describes the investigation of the fate of hydrocarbons in stormwater bioretention areas and those mechanisms that affect hydrocarbon fate in such systems. Seventy-five samples from 58 bioretention areas were collected and analyzed to measure total petroleum hydrocarbon (TPH) residual and biodegradation functional genes. TPH residual in bioretention areas was greater than background sites but low overall (<3 µg/kg), and well below either the TPH concentration of concern or the expected concentration, assuming no losses. Bioretention areas with deep-root vegetation contained significantly greater quantites of bacterial 16S rRNA genes and two functional genes involved in hydrocarbon biodegradation. Field soils were capable of mineralizing naphthalene, a polycyclic aromatic hydrocarbon (PAH) when incubated in the laboratory. In an additional laboratory investigation, a column study was initiated to comprehensively determine naphthalene fate in a simulated bioretention cell using a 14C-labeled tracer. Sorption to soil was the greatest sink of naphthalene in the columns, although biodegradation and vegetative uptake were also important loss mechanisms. Little leaching occurred following the first flush, and volatilization was insignificant. Significant enrichment of naphthalene degrading bacteria occurred over the course of the experiment as a result of naphthalene exposure. This was evident from enhanced naphthalene biodegradation kinetics (measured via batch tests), significant increases in naphthalene dioxygenase gene quantities, and a significant correlation observed between naphthalene residual and biodegradation functional genes. Vegetated columns outperformed the unplanted control column in terms of total naphthalene removal and biodegradation kinetics. As a result of these experiments, a final study focused on why planted systems outperform unplanted systems was conducted. Plant root exudates were harvested from hydroponic setups for three

  8. Cell fate determination in cisplatin resistance and chemosensitization.

    PubMed

    Luong, Khanh V; Wang, Ling; Roberts, Brett J; Wahl, James K; Peng, Aimin

    2016-04-26

    Understanding the determination of cell fate choices after cancer treatment will shed new light on cancer resistance. In this study, we quantitatively analyzed the individual cell fate choice in resistant UM-SCC-38 head and neck cancer cells exposed to cisplatin. Our study revealed a highly heterogeneous pattern of cell fate choices in UM-SCC-38 cells, in comparison to that of the control, non-tumorigenic keratinocyte HaCaT cells. In both UM-SCC-38 and HaCaT cell lines, the majority of cell death occurred during the immediate interphase without mitotic entry, whereas significant portions of UM-SCC-38 cells survived the treatment via either checkpoint arrest or checkpoint slippage. Interestingly, checkpoint slippage occurred predominantly in cells treated in late S and G2 phases, and cells in M-phase were hypersensitive to cisplatin. Moreover, although the cisplatin-resistant progression of mitosis exhibited no delay in general, prolonged mitosis was correlated with the induction of cell death in mitosis. The finding thus suggested a combinatorial treatment using cisplatin and an agent that blocks mitotic exit. Consistently, we showed a strong synergy between cisplatin and the proteasome inhibitor Mg132. Finally, targeting the DNA damage checkpoint using inhibitors of ATR, but not ATM, effectively sensitized UM-SCC-38 to cisplatin treatment. Surprisingly, checkpoint targeting eliminated both checkpoint arrest and checkpoint slippage, and augmented the induction of cell death in interphase without mitotic entry. Taken together, our study, by profiling cell fate determination after cisplatin treatment, reveals new insights into chemoresistance and suggests combinatorial strategies that potentially overcome cancer resistance. PMID:26993599

  9. Cell fate determination in cisplatin resistance and chemosensitization

    PubMed Central

    Luong, Khanh V.; Wang, Ling; Roberts, Brett J.; Wahl, James K.; Peng, Aimin

    2016-01-01

    Understanding the determination of cell fate choices after cancer treatment will shed new light on cancer resistance. In this study, we quantitatively analyzed the individual cell fate choice in resistant UM-SCC-38 head and neck cancer cells exposed to cisplatin. Our study revealed a highly heterogeneous pattern of cell fate choices in UM-SCC-38 cells, in comparison to that of the control, non-tumorigenic keratinocyte HaCaT cells. In both UM-SCC-38 and HaCaT cell lines, the majority of cell death occurred during the immediate interphase without mitotic entry, whereas significant portions of UM-SCC-38 cells survived the treatment via either checkpoint arrest or checkpoint slippage. Interestingly, checkpoint slippage occurred predominantly in cells treated in late S and G2 phases, and cells in M-phase were hypersensitive to cisplatin. Moreover, although the cisplatin-resistant progression of mitosis exhibited no delay in general, prolonged mitosis was correlated with the induction of cell death in mitosis. The finding thus suggested a combinatorial treatment using cisplatin and an agent that blocks mitotic exit. Consistently, we showed a strong synergy between cisplatin and the proteasome inhibitor Mg132. Finally, targeting the DNA damage checkpoint using inhibitors of ATR, but not ATM, effectively sensitized UM-SCC-38 to cisplatin treatment. Surprisingly, checkpoint targeting eliminated both checkpoint arrest and checkpoint slippage, and augmented the induction of cell death in interphase without mitotic entry. Taken together, our study, by profiling cell fate determination after cisplatin treatment, reveals new insights into chemoresistance and suggests combinatorial strategies that potentially overcome cancer resistance. PMID:26993599

  10. Pax6 is a human neuroectoderm cell fate determinant

    PubMed Central

    Zhang, Xiaoqing; Huang, Cindy T.; Chen, Jing; Pankratz, Matthew T.; Xi, Jiajie; Li, Jin; Yang, Ying; LaVaute, Timothy M.; Li, Xue-Jun; Ayala, Melvin; Bondarenko, Gennadiy I.; Du, Zhong-Wei; Jin, Ying; Golos, Thaddeus G.; Zhang, Su-Chun

    2010-01-01

    SUMMARY The transcriptional regulation of neuroectoderm (NE) specification is unknown. Here we show that Pax6 is uniformly expressed in early NE cells of human fetuses and those differentiated from human embryonic stem cells (hESCs). This contrasts the later expression of Pax6 in restricted mouse brain regions. Knockdown of Pax6 blocks NE specification from hESCs. Overexpression of either Pax6a or Pax6b, but not Pax6 PD, triggers hESC differentiation. However, only Pax6a converts hESCs to NE. In contrast, neither loss nor gain of function of Pax6 affects mouse NE specification. Both Pax6a and Pax6b bind to pluripotent gene promoters but only Pax6a binds to NE genes during human NE specification. These findings indicate that Pax6 is a transcriptional determinant of the human NE and suggest that Pax6a and Pax6b coordinate with each other in determining the transition from pluripotency to the NE fate in human by differentially targeting pluripotent and NE genes. PMID:20621053

  11. Chemicals as the Sole Transformers of Cell Fate

    PubMed Central

    Ebrahimi, Behnam

    2016-01-01

    Forced expression of lineage-specific transcription factors in somatic cells can result in the generation of different cell types in a process named direct reprogramming, bypassing the pluripotent state. However, the introduction of transgenes limits the therapeutic applications of the produced cells. Numerous small-molecules have been introduced in the field of stem cell biology capable of governing self-renewal, reprogramming, transdifferentiation and regeneration. These chemical compounds are versatile tools for cell fate conversion toward desired outcomes. Cell fate conversion using small-molecules alone (chemical reprogramming) has superiority over arduous traditional genetic techniques in several aspects. For instance, rapid, transient, and reversible effects in activation and inhibition of functions of specific proteins are of the profits of small-molecules. They are cost-effective, have a long half-life, diversity on structure and function, and allow for temporal and flexible regulation of signaling pathways. Additionally, their effects could be adjusted by fine-tuning concentrations and combinations of different small-molecules. Therefore, chemicals are powerful tools in cell fate conversion and study of stem cell and chemical biology in vitro and in vivo. Moreover, transgene-free and chemical-only transdifferentiation approaches provide alternative strategies for the generation of various cell types, disease modeling, drug screening, and regenerative medicine. The current review gives an overview of the recent findings concerning transdifferentiation by only small-molecules without the use of transgenes. PMID:27426081

  12. Reporter gene technologies for imaging cell fates in hematopoiesis.

    PubMed

    Kusy, Sophie; Contag, Christopher H

    2014-01-01

    Advances in noninvasive imaging technologies that allow for in vivo dynamic monitoring of cells and cellular function in living research subjects have revealed new insights into cell biology in the context of intact organs and their native environment. In the field of hematopoiesis and stem cell research, studies of cell trafficking involved in injury repair and hematopoietic engraftment have made great progress using these new tools. Stem cells present unique challenges for imaging since after transplantation, they proliferate dramatically and differentiate. Therefore, the imaging modality used needs to have a large dynamic range, and the genetic regulatory elements used need to be stably expressed during differentiation. Multiple imaging technologies using different modalities are available, and each varies in sensitivity, ease of data acquisition, signal to noise ratios (SNR), substrate availability, and other parameters that affect utility for monitoring cell fates and function. For a given application, there may be several different approaches that can be used. For mouse models, clinically validated technologies such as magnetic resonance imaging (MRI) and positron emission tomography (PET) have been joined by optical imaging techniques such as in vivo bioluminescence imaging (BLI) and fluorescence imaging (FLI), and all have been used to monitor bone marrow and stem cells after transplantation into mice. Photoacoustic imaging that utilizes the sound created by the thermal expansion of absorbed light to generate an image best represents hybrid technologies. Each modality requires that the cells of interest be marked with a genetic reporter that acts as a label making them uniquely visible using that technology. For each modality, there are several labels to choose from. Multiple methods for applying these different labels are available. This chapter provides an overview of the imaging technologies and commonly used labels for each, as well as detailed

  13. Cell fate decision mediated by p53 pulses

    PubMed Central

    Zhang, Xiao-Peng; Liu, Feng; Cheng, Zhang; Wang, Wei

    2009-01-01

    The tumor suppressor p53 plays a crucial role in cellular response to various stresses. Recent experiments have shown that p53 level exhibits a series of pulses after DNA damage caused by ionizing radiation (IR). However, how the p53 pulses govern cell survival and death remains unclear. Here, we develop an integrated model with four modules for the p53 network and explore the mechanism for cell fate decision based on the dynamics of the network. By numerical simulations, the following processes are characterized. First, DNA repair proteins bind to IR-induced double-strand breaks, forming complexes, which are then detected by ataxia telangiectasia mutated (ATM). Activated ATM initiates the p53 oscillator to produce pulses. Consequently, the target genes of p53 are selectively induced to control cell fate. We propose that p53 promotes the repair of minor DNA damage but suppresses the repair of severe damage. We demonstrate that cell fate is determined by the number of p53 pulses relying on the extent of DNA damage. At low damage levels, few p53 pulses evoke cell cycle arrest by inducing p21 and promote cell survival, whereas at high damage levels, sustained p53 pulses trigger apoptosis by inducing p53AIP1. We find that p53 can effectively maintain genomic integrity by regulating the efficiency and fidelity of DNA repair. We also show that stochasticity in the generation and repair of DNA damage leads to variability in cell fate. These findings are consistent with experimental observations and advance our understanding of the dynamics and functions of the p53 network. PMID:19617533

  14. Mechanics Regulates Fate Decisions of Human Embryonic Stem Cells

    PubMed Central

    Sun, Yubing; Villa-Diaz, Luis G.; Lam, Raymond H. W.; Chen, Weiqiang; Krebsbach, Paul H.; Fu, Jianping

    2012-01-01

    Research on human embryonic stem cells (hESCs) has attracted much attention given their great potential for tissue regenerative therapy and fundamental developmental biology studies. Yet, there is still limited understanding of how mechanical signals in the local cellular microenvironment of hESCs regulate their fate decisions. Here, we applied a microfabricated micromechanical platform to investigate the mechanoresponsive behaviors of hESCs. We demonstrated that hESCs are mechanosensitive, and they could increase their cytoskeleton contractility with matrix rigidity. Furthermore, rigid substrates supported maintenance of pluripotency of hESCs. Matrix mechanics-mediated cytoskeleton contractility might be functionally correlated with E-cadherin expressions in cell-cell contacts and thus involved in fate decisions of hESCs. Our results highlighted the important functional link between matrix rigidity, cellular mechanics, and pluripotency of hESCs and provided a novel approach to characterize and understand mechanotransduction and its involvement in hESC function. PMID:22615930

  15. Notch signaling differentially regulates the cell fate of early endocrine precursor cells and their maturing descendants in the mouse pancreas and intestine.

    PubMed

    Li, Hui Joyce; Kapoor, Archana; Giel-Moloney, Maryann; Rindi, Guido; Leiter, Andrew B

    2012-11-15

    Notch signaling inhibits differentiation of endocrine cells in the pancreas and intestine. In a number of cases, the observed inhibition occurred with Notch activation in multipotential cells, prior to the initiation of endocrine differentiation. It has not been established how direct activation of Notch in endocrine precursor cells affects their subsequent cell fate. Using conditional activation of Notch in cells expressing Neurogenin3 or NeuroD1, we examined the effects of Notch in both organs, on cell fate of early endocrine precursors and maturing endocrine-restricted cells, respectively. Notch did not preclude the differentiation of a limited number of endocrine cells in either organ when activated in Ngn3(+) precursor cells. In addition, in the pancreas most Ngn3(+) cells adopted a duct but not acinar cell fate; whereas in intestinal Ngn3(+) cells, Notch favored enterocyte and goblet cell fates, while selecting against endocrine and Paneth cell differentiation. A small fraction of NeuroD1(+) cells in the pancreas retain plasticity to respond to Notch, giving rise to intraislet ductules as well as cells with no detectable pancreatic lineage markers that appear to have limited ultrastructural features of both endocrine and duct cells. These results suggest that Notch directly regulates cell fate decisions in multipotential early endocrine precursor cells. Some maturing endocrine-restricted NeuroD1(+) cells in the pancreas switch to the duct lineage in response to Notch, indicating previously unappreciated plasticity at such a late stage of endocrine differentiation.

  16. Hedgehog and Resident Vascular Stem Cell Fate

    PubMed Central

    Mooney, Ciaran J.; Hakimjavadi, Roya; Fitzpatrick, Emma; Kennedy, Eimear; Walls, Dermot; Morrow, David; Redmond, Eileen M.; Cahill, Paul A.

    2015-01-01

    The Hedgehog pathway is a pivotal morphogenic driver during embryonic development and a key regulator of adult stem cell self-renewal. The discovery of resident multipotent vascular stem cells and adventitial progenitors within the vessel wall has transformed our understanding of the origin of medial and neointimal vascular smooth muscle cells (SMCs) during vessel repair in response to injury, lesion formation, and overall disease progression. This review highlights the importance of components of the Hh and Notch signalling pathways within the medial and adventitial regions of adult vessels, their recapitulation following vascular injury and disease progression, and their putative role in the maintenance and differentiation of resident vascular stem cells to vascular lineages from discrete niches within the vessel wall. PMID:26064136

  17. Actin - a biosensor that determines cell fate in yeasts.

    PubMed

    Smethurst, Daniel G J; Dawes, Ian W; Gourlay, Campbell W

    2014-02-01

    The decision to proliferate, to activate stress response mechanisms or to initiate cell death lies at the heart of the maintenance of a healthy cell population. Within multicellular and colony-forming single-celled organisms, such as yeasts, the functionality of cellular compartments that connect signalling to cell fate must be maintained to maximise adaptability and survival. The actin cytoskeleton is involved in processes such as the regulation of membrane microcompartments, receptor internalisation and the control of master regulatory GTPases, which govern cell decision-making. This affords the actin cytoskeleton a central position within cell response networks. In this sense, a functional actin cytoskeleton is essential to efficiently connect information input to response at the level of the cell. Recent research from fungal, plant and mammalian cells systems has highlighted that actin can trigger apoptotic death in cells that become incompetent to respond to environmental cues. It may also be the case that this property has been appropriated by microorganisms competing for niche environments within a human host. Here, we discuss the research that has been carried out in yeast that links actin to signalling processes and cell fate that supports its role as a biosensor.

  18. Reliable binary cell-fate decisions based on oscillations

    NASA Astrophysics Data System (ADS)

    Pfeuty, B.; Kaneko, K.

    2014-02-01

    Biological systems have often to perform binary decisions under highly dynamic and noisy environments, such as during cell-fate determination. These decisions can be implemented by two main bifurcation mechanisms based on the transitions from either monostability or oscillation to bistability. We compare these two mechanisms by using stochastic models with time-varying fields and by establishing asymptotic formulas for the choice probabilities. Different scaling laws for decision sensitivity with respect to noise strength and signal timescale are obtained, supporting a role for oscillatory dynamics in performing noise-robust and temporally tunable binary decision-making. This result provides a rationale for recent experimental evidences showing that oscillatory expression of proteins often precedes binary cell-fate decisions.

  19. Different cell fates after mitotic slippage: From aneuploidy to polyploidy.

    PubMed

    Ohashi, Akihiro

    2016-03-01

    The molecular mechanism responsible for cell fate after mitotic slippage remains unclear. We investigated the different postmitotic effects of aneuploidy versus polyploidy using chemical inhibitors of centromere-associated protein-E (CENP-E) and kinesin family member 11 (KIF11, also known as Eg5). Aneuploidy caused substantial proteotoxic stress and DNA damage accompanied by p53-mediated postmitotic apoptosis, whereas polyploidy did not induce these antiproliferative effects. PMID:27308610

  20. Magnetic resonance imaging of transplanted stem cell fate in stroke.

    PubMed

    Aghayan, Hamid Reza; Soleimani, Masoud; Goodarzi, Parisa; Norouzi-Javidan, Abbas; Emami-Razavi, Seyed Hasan; Larijani, Bagher; Arjmand, Babak

    2014-05-01

    Nowadays, scientific findings in the field of regeneration of nervous system have revealed the possibility of stem cell based therapies for damaged brain tissue related disorders like stroke. Furthermore, to achieve desirable outcomes from cellular therapies, one needs to monitor the migration, engraftment, viability, and also functional fate of transplanted stem cells. Magnetic resonance imaging is an extremely versatile technique for this purpose, which has been broadly used to study stroke and assessment of therapeutic role of stem cells. In this review we searched in PubMed search engine by using following keywords; "Stem Cells", "Cell Tracking", "Stroke", "Stem Cell Transplantation", "Nanoparticles", and "Magnetic Resonance Imaging" as entry terms and based on the mentioned key words, the search period was set from 1976 to 2012. The main purpose of this article is describing various advantages of molecular and magnetic resonance imaging of stem cells, with focus on translation of stem cell research to clinical research.

  1. Intestinal Neurogenin 3 Directs Differentiation of a Bipotential Secretory Progenitor to Endocrine Cell Rather than Goblet Cell Fate

    PubMed Central

    López-Díaz, Lymari; Jain, Renu N.; Keeley, Theresa M.; VanDussen, Kelli L.; Brunkan, Cynthia S.; Gumucio, Deborah L.; Samuelson, Linda C.

    2009-01-01

    Neurogenin 3 is essential for enteroendocrine cell development; however, it is unknown whether this transcription factor is sufficient to induce an endocrine program in the intestine or how it affects the development of other epithelial cells originating from common progenitors. In this study, the mouse villin promoter was used to drive Neurogenin 3 expression throughout the developing epithelium to measure the affect on cell fate. Although the general morphology of the intestine was unchanged, transgenic founder embryos displayed increased numbers of cells expressing the pan-endocrine marker chromogranin A. Accordingly, expression of several hormones and pro-endocrine transcription factors were increased in the transgenics suggesting that Neurogenin 3 stimulated a program of terminal enteroendocrine cell development. To test whether increased endocrine cell differentiation affected the development of other secretory cell lineages, we quantified goblet cells, the only other secretory cell formed in embryonic intestine. The Neurogenin 3-expressing transgenics had decreased numbers of goblet cells in correspondence to the increase in endocrine cells, with no change in the total secretory cell numbers. Thus, our data suggest that Neurogenin 3 can redirect the differentiation of bipotential secretory progenitors to endocrine rather than goblet cell fate. PMID:17706959

  2. Phage DNA dynamics in cells with different fates.

    PubMed

    Shao, Qiuyan; Hawkins, Alexander; Zeng, Lanying

    2015-04-21

    Bacteriophage λ begins its infection cycle by ejecting its DNA into its host Escherichia coli cell, after which either a lytic or a lysogenic pathway is followed, resulting in different cell fates. In this study, using a new technique to monitor the spatiotemporal dynamics of the phage DNA in vivo, we found that the phage DNA moves via two distinct modes, localized motion and motion spanning the whole cell. One or the other motion is preferred, depending on where the phage DNA is ejected into the cell. By examining the phage DNA trajectories, we found the motion to be subdiffusive. Moreover, phage DNA motion is the same in the early phase of the infection cycle, irrespective of whether the lytic or lysogenic pathway is followed; hence, cell-fate decision-making appears not to be correlated with the phage DNA motion. However, after the cell commits to one pathway or the other, phage DNA movement slows during the late phase of the lytic cycle, whereas it remains the same during the entire lysogenic cycle. Throughout the infection cycle, phage DNA prefers the regions around the quarter positions of the cell. PMID:25902444

  3. Extracellular-matrix tethering regulates stem-cell fate

    NASA Astrophysics Data System (ADS)

    Trappmann, Britta; Gautrot, Julien E.; Connelly, John T.; Strange, Daniel G. T.; Li, Yuan; Oyen, Michelle L.; Cohen Stuart, Martien A.; Boehm, Heike; Li, Bojun; Vogel, Viola; Spatz, Joachim P.; Watt, Fiona M.; Huck, Wilhelm T. S.

    2012-07-01

    To investigate how substrate properties influence stem-cell fate, we cultured single human epidermal stem cells on polydimethylsiloxane (PDMS) and polyacrylamide (PAAm) hydrogel surfaces, 0.1 kPa-2.3 MPa in stiffness, with a covalently attached collagen coating. Cell spreading and differentiation were unaffected by polydimethylsiloxane stiffness. However, cells on polyacrylamide of low elastic modulus (0.5 kPa) could not form stable focal adhesions and differentiated as a result of decreased activation of the extracellular-signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling pathway. The differentiation of human mesenchymal stem cells was also unaffected by PDMS stiffness but regulated by the elastic modulus of PAAm. Dextran penetration measurements indicated that polyacrylamide substrates of low elastic modulus were more porous than stiff substrates, suggesting that the collagen anchoring points would be further apart. We then changed collagen crosslink concentration and used hydrogel-nanoparticle substrates to vary anchoring distance at constant substrate stiffness. Lower collagen anchoring density resulted in increased differentiation. We conclude that stem cells exert a mechanical force on collagen fibres and gauge the feedback to make cell-fate decisions.

  4. Competition in Notch Signaling with Cis Enriches Cell Fate Decisions

    PubMed Central

    Formosa-Jordan, Pau; Ibañes, Marta

    2014-01-01

    Notch signaling is involved in cell fate choices during the embryonic development of Metazoa. Commonly, Notch signaling arises from the binding of the Notch receptor to its ligands in adjacent cells driving cell-to-cell communication. Yet, cell-autonomous control of Notch signaling through both ligand-dependent and ligand-independent mechanisms is known to occur as well. Examples include Notch signaling arising in the absence of ligand binding, and cis-inhibition of Notch signaling by titration of the Notch receptor upon binding to its ligands within a single cell. Increasing experimental evidences support that the binding of the Notch receptor with its ligands within a cell (cis-interactions) can also trigger a cell-autonomous Notch signal (cis-signaling), whose potential effects on cell fate decisions and patterning remain poorly understood. To address this question, herein we mathematically and computationally investigate the cell states arising from the combination of cis-signaling with additional Notch signaling sources, which are either cell-autonomous or involve cell-to-cell communication. Our study shows that cis-signaling can switch from driving cis-activation to effectively perform cis-inhibition and identifies under which conditions this switch occurs. This switch relies on the competition between Notch signaling sources, which share the same receptor but differ in their signaling efficiency. We propose that the role of cis-interactions and their signaling on fine-grained patterning and cell fate decisions is dependent on whether they drive cis-inhibition or cis-activation, which could be controlled during development. Specifically, cis-inhibition and not cis-activation facilitates patterning and enriches it by modulating the ratio of cells in the high-ligand expression state, by enabling additional periodic patterns like stripes and by allowing localized patterning highly sensitive to the precursor state and cell-autonomous bistability. Our study

  5. Cell Signaling and Transcription Factors Regulating Cell Fate During Formation of the Mouse Blastocyst

    PubMed Central

    Frum, Tristan; Ralston, Amy

    2015-01-01

    The first cell fate decisions during mammalian development establish tissues essential for healthy pregnancy. The mouse has served as a valuable model for discovering pathways regulating the first cell fate decisions, because of the ease with which early embryos can be recovered and an arsenal of classical and emerging methods for manipulating gene expression. Here we summarize the major pathways that govern the first cell fate decisions in mouse development. This knowledge serves as a paradigm for exploring how emergent properties of a self-organizing system can dynamically regulate gene expression and cell fate plasticity. Moreover, it brings to light the processes that establish healthy pregnancy and embryonic stem (ES) cells. We also describe unsolved mysteries and new technologies that could help overcome experimental challenges in the field. PMID:25999217

  6. Yap and Taz regulate retinal pigment epithelial cell fate

    PubMed Central

    Miesfeld, Joel B.; Gestri, Gaia; Clark, Brian S.; Flinn, Michael A.; Poole, Richard J.; Bader, Jason R.; Besharse, Joseph C.; Wilson, Stephen W.; Link, Brian A.

    2015-01-01

    The optic vesicle comprises a pool of bi-potential progenitor cells from which the retinal pigment epithelium (RPE) and neural retina fates segregate during ocular morphogenesis. Several transcription factors and signaling pathways have been shown to be important for RPE maintenance and differentiation, but an understanding of the initial fate specification and determination of this ocular cell type is lacking. We show that Yap/Taz-Tead activity is necessary and sufficient for optic vesicle progenitors to adopt RPE identity in zebrafish. A Tead-responsive transgene is expressed within the domain of the optic cup from which RPE arises, and Yap immunoreactivity localizes to the nuclei of prospective RPE cells. yap (yap1) mutants lack a subset of RPE cells and/or exhibit coloboma. Loss of RPE in yap mutants is exacerbated in combination with taz (wwtr1) mutant alleles such that, when Yap and Taz are both absent, optic vesicle progenitor cells completely lose their ability to form RPE. The mechanism of Yap-dependent RPE cell type determination is reliant on both nuclear localization of Yap and interaction with a Tead co-factor. In contrast to loss of Yap and Taz, overexpression of either protein within optic vesicle progenitors leads to ectopic pigmentation in a dosage-dependent manner. Overall, this study identifies Yap and Taz as key early regulators of RPE genesis and provides a mechanistic framework for understanding the congenital ocular defects of Sveinsson's chorioretinal atrophy and congenital retinal coloboma. PMID:26209646

  7. From priming to plasticity: the changing fate of rhizodermic cells.

    PubMed

    Savage, Natasha Saint; Schmidt, Wolfgang

    2008-01-01

    The fate of root epidermal cells is controlled by a complex interplay of transcriptional regulators, generating a genetically determined, position-biased arrangement of root hair cells. This pattern is altered during postembryonic development and in response to environmental signals to confer developmental plasticity that acclimates the plant to the prevailing conditions. Based on the hypothesis that events downstream of this initial mechanism can modulate the pattern installed during embryogenesis, we have developed a reaction diffusion model that reproduces the root hair patterning previously observed experimentally. Under all growth conditions, an almost equal spacing between root hair forming cells was observed both in vitro and in silico, indicating that long-range intercellular communication is crucial for the trichoblasts' decision to form a root hair. We assume that a hair growth promoter (HGP) is upregulated in root-hair-forming cells by a trichoblast-specific component. Once established, HGP production is self-enhancing. The autocatalytic regulation of HGP is antagonized by an HGP-produced hair growth inhibitor (HGI). HGI is exported from trichoblasts and diffuses to neighboring cells, where it inhibits further HGP production and promotes the non-hair cell fate. Under conditions of phosphate deficiency, we hypothesise that HGP production is increased and HGI diffusion rate is reduced, leading to a position-independent formation of extra root hairs.

  8. Engineering Cell Instructive Materials To Control Cell Fate and Functions through Material Cues and Surface Patterning.

    PubMed

    Ventre, Maurizio; Netti, Paolo A

    2016-06-22

    Mastering the interaction between cells and extracellular environment is a fundamental prerequisite in order to engineer functional biomaterial interfaces able to instruct cells with specific commands. Such advanced biomaterials might find relevant application in prosthesis design, tissue engineering, diagnostics and stem cell biology. Because of the highly complex, dynamic, and multifaceted context, a thorough understanding of the cell-material crosstalk has not been achieved yet; however, a variety of material features including biological cues, topography, and mechanical properties have been proved to impact the strength and the nature of the cell-material interaction, eventually affecting cell fate and functions. Although the nature of these three signals may appear very different, they are equated by their participation in the same material-cytoskeleton crosstalk pathway as they regulate cell adhesion events. In this work we present recent and relevant findings on the material-induced cell responses, with a particular emphasis on how the presentation of biochemical/biophysical signals modulates cell behavior. Finally, we summarize and discuss the literature data to draw out unifying elements concerning cell recognition of and reaction to signals displayed by material surfaces.

  9. Intracellular GTP level determines cell's fate toward differentiation and apoptosis

    SciTech Connect

    Meshkini, Azadeh; Yazdanparast, Razieh Nouri, Kazem

    2011-06-15

    Since the adequate supply of guanine nucleotides is vital for cellular activities, limitation of their syntheses would certainly result in modulation of cellular fate toward differentiation and apoptosis. The aim of this study was to set a correlation between the intracellular level of GTP and the induction of relevant signaling pathways involved in the cell's fate toward life or death. In that regard, we measured the GTP level among human leukemia K562 cells exposed to mycophenolic acid (MPA) or 3-hydrogenkwadaphnin (3-HK) as two potent inosine monophosphate dehydrogenase inhibitors. Our results supported the maturation of the cells when the intracellular GTP level was reduced by almost 30-40%. Under these conditions, 3-HK and/or MPA caused up-regulation of PKC{alpha} and PI3K/AKT pathways. Furthermore, co-treatment of cells with hypoxanthine plus 3-HK or MPA, which caused a reduction of about 60% in the intracellular GTP levels, led to apoptosis and activation of mitochondrial pathways through inverse regulation of Bcl-2/Bax expression and activation of caspase-3. Moreover, our results demonstrated that attenuation of GTP by almost 60% augmented the intracellular ROS and nuclear localization of p21 and subsequently led to cell death. These results suggest that two different threshold levels of GTP are needed for induction of differentiation and/or ROS-associated apoptosis. - Graphical abstract: Display Omitted

  10. Nuclear envelope and genome interactions in cell fate

    PubMed Central

    Talamas, Jessica A.; Capelson, Maya

    2015-01-01

    The eukaryotic cell nucleus houses an organism’s genome and is the location within the cell where all signaling induced and development-driven gene expression programs are ultimately specified. The genome is enclosed and separated from the cytoplasm by the nuclear envelope (NE), a double-lipid membrane bilayer, which contains a large variety of trans-membrane and associated protein complexes. In recent years, research regarding multiple aspects of the cell nucleus points to a highly dynamic and coordinated concert of efforts between chromatin and the NE in regulation of gene expression. Details of how this concert is orchestrated and how it directs cell differentiation and disease are coming to light at a rapid pace. Here we review existing and emerging concepts of how interactions between the genome and the NE may contribute to tissue specific gene expression programs to determine cell fate. PMID:25852741

  11. Matrix mechanics and fluid shear stress control stem cells fate in three dimensional microenvironment.

    PubMed

    Chen, Guobao; Lv, Yonggang; Guo, Pan; Lin, Chongwen; Zhang, Xiaomei; Yang, Li; Xu, Zhiling

    2013-07-01

    Stem cells have the ability to self-renew and to differentiate into multiple mature cell types during early life and growth. Stem cells adhesion, proliferation, migration and differentiation are affected by biochemical, mechanical and physical surface properties of the surrounding matrix in which stem cells reside and stem cells can sensitively feel and respond to the microenvironment of this matrix. More and more researches have proven that three dimensional (3D) culture can reduce the gap between cell culture and physiological environment where cells always live in vivo. This review summarized recent findings on the studies of matrix mechanics that control stem cells (primarily mesenchymal stem cells (MSCs)) fate in 3D environment, including matrix stiffness and extracellular matrix (ECM) stiffness. Considering the exchange of oxygen and nutrients in 3D culture, the effect of fluid shear stress (FSS) on fate decision of stem cells was also discussed in detail. Further, the difference of MSCs response to matrix stiffness between two dimensional (2D) and 3D conditions was compared. Finally, the mechanism of mechanotransduction of stem cells activated by matrix mechanics and FSS in 3D culture was briefly pointed out.

  12. Optogenetic Control of Nodal Signaling Reveals a Temporal Pattern of Nodal Signaling Regulating Cell Fate Specification during Gastrulation.

    PubMed

    Sako, Keisuke; Pradhan, Saurabh J; Barone, Vanessa; Inglés-Prieto, Álvaro; Müller, Patrick; Ruprecht, Verena; Čapek, Daniel; Galande, Sanjeev; Janovjak, Harald; Heisenberg, Carl-Philipp

    2016-07-19

    During metazoan development, the temporal pattern of morphogen signaling is critical for organizing cell fates in space and time. Yet, tools for temporally controlling morphogen signaling within the embryo are still scarce. Here, we developed a photoactivatable Nodal receptor to determine how the temporal pattern of Nodal signaling affects cell fate specification during zebrafish gastrulation. By using this receptor to manipulate the duration of Nodal signaling in vivo by light, we show that extended Nodal signaling within the organizer promotes prechordal plate specification and suppresses endoderm differentiation. Endoderm differentiation is suppressed by extended Nodal signaling inducing expression of the transcriptional repressor goosecoid (gsc) in prechordal plate progenitors, which in turn restrains Nodal signaling from upregulating the endoderm differentiation gene sox17 within these cells. Thus, optogenetic manipulation of Nodal signaling identifies a critical role of Nodal signaling duration for organizer cell fate specification during gastrulation. PMID:27396324

  13. Matrix Stiffness and Nanoscale Spatial Organization of Cell-Adhesive Ligands Direct Stem Cell Fate.

    PubMed

    Ye, Kai; Wang, Xuan; Cao, Luping; Li, Shiyu; Li, Zhenhua; Yu, Lin; Ding, Jiandong

    2015-07-01

    One of the breakthroughs in biomaterials and regenerative medicine in the latest decade is the finding that matrix stiffness affords a crucial physical cue of stem cell differentiation. This statement was recently challenged by another understanding that protein tethering on material surfaces instead of matrix stiffness was the essential cue to regulate stem cells. Herein, we employed nonfouling poly(ethylene glycol) (PEG) hydrogels as the matrix to prevent nonspecific protein adsorption, and meanwhile covalently bound cell-adhesive arginine-glycine-aspartate (RGD) peptides onto the hydrogel surfaces in the form of well-defined nanoarrays to control specific cell adhesion. This approach enables the decoupling of the effects of matrix stiffness and surface chemistry. Mesenchymal stem cells (MSCs) were cultured on four substrates (two compressive moduli of the PEG hydrogels multiplied by two RGD nanospacings) and incubated in the mixed osteogenic and adipogenic medium. The results illustrate unambiguously that matrix stiffness is a potent regulator of stem cell differentiation. Moreover, we reveal that RGD nanospacing affects spreading area and differentiation of rat MSCs, regardless of the hydrogel stiffness. Therefore, both matrix stiffness and nanoscale spatial organization of cell-adhesive ligands direct stem cell fate.

  14. Matrix Stiffness and Nanoscale Spatial Organization of Cell-Adhesive Ligands Direct Stem Cell Fate.

    PubMed

    Ye, Kai; Wang, Xuan; Cao, Luping; Li, Shiyu; Li, Zhenhua; Yu, Lin; Ding, Jiandong

    2015-07-01

    One of the breakthroughs in biomaterials and regenerative medicine in the latest decade is the finding that matrix stiffness affords a crucial physical cue of stem cell differentiation. This statement was recently challenged by another understanding that protein tethering on material surfaces instead of matrix stiffness was the essential cue to regulate stem cells. Herein, we employed nonfouling poly(ethylene glycol) (PEG) hydrogels as the matrix to prevent nonspecific protein adsorption, and meanwhile covalently bound cell-adhesive arginine-glycine-aspartate (RGD) peptides onto the hydrogel surfaces in the form of well-defined nanoarrays to control specific cell adhesion. This approach enables the decoupling of the effects of matrix stiffness and surface chemistry. Mesenchymal stem cells (MSCs) were cultured on four substrates (two compressive moduli of the PEG hydrogels multiplied by two RGD nanospacings) and incubated in the mixed osteogenic and adipogenic medium. The results illustrate unambiguously that matrix stiffness is a potent regulator of stem cell differentiation. Moreover, we reveal that RGD nanospacing affects spreading area and differentiation of rat MSCs, regardless of the hydrogel stiffness. Therefore, both matrix stiffness and nanoscale spatial organization of cell-adhesive ligands direct stem cell fate. PMID:26027605

  15. Cell fate regulation governed by a repurposed bacterial histidine kinase

    DOE PAGES

    Childers, W. Seth; Xu, Qingping; Mann, Thomas H.; Mathews, Irimpan I.; Blair, Jimmy A.; Deacon, Ashley M.; Shapiro, Lucy; Stock, Ann M.

    2014-10-28

    One of the simplest organisms to divide asymmetrically is the bacterium Caulobacter crescentus. The DivL pseudo-histidine kinase, positioned at one cell pole, regulates cell-fate by controlling the activation of the global transcription factor CtrA via an interaction with the response regulator (RR) DivK. DivL uniquely contains a tyrosine at the histidine phosphorylation site, and can achieve these regulatory functions in vivo without kinase activity. Determination of the DivL crystal structure and biochemical analysis of wild-type and site-specific DivL mutants revealed that the DivL PAS domains regulate binding specificity for DivK~P over DivK, which is modulated by an allosteric intramolecular interactionmore » between adjacent domains. We discovered that DivL's catalytic domains have been repurposed as a phosphospecific RR input sensor, thereby reversing the flow of information observed in conventional histidine kinase (HK)-RR systems and coupling a complex network of signaling proteins for cell-fate regulation.« less

  16. Cell fate regulation governed by a repurposed bacterial histidine kinase

    SciTech Connect

    Childers, W. Seth; Xu, Qingping; Mann, Thomas H.; Mathews, Irimpan I.; Blair, Jimmy A.; Deacon, Ashley M.; Shapiro, Lucy; Stock, Ann M.

    2014-10-28

    One of the simplest organisms to divide asymmetrically is the bacterium Caulobacter crescentus. The DivL pseudo-histidine kinase, positioned at one cell pole, regulates cell-fate by controlling the activation of the global transcription factor CtrA via an interaction with the response regulator (RR) DivK. DivL uniquely contains a tyrosine at the histidine phosphorylation site, and can achieve these regulatory functions in vivo without kinase activity. Determination of the DivL crystal structure and biochemical analysis of wild-type and site-specific DivL mutants revealed that the DivL PAS domains regulate binding specificity for DivK~P over DivK, which is modulated by an allosteric intramolecular interaction between adjacent domains. We discovered that DivL's catalytic domains have been repurposed as a phosphospecific RR input sensor, thereby reversing the flow of information observed in conventional histidine kinase (HK)-RR systems and coupling a complex network of signaling proteins for cell-fate regulation.

  17. Spatially patterned matrix elasticity directs stem cell fate

    NASA Astrophysics Data System (ADS)

    Yang, Chun; DelRio, Frank W.; Ma, Hao; Killaars, Anouk R.; Basta, Lena P.; Kyburz, Kyle A.; Anseth, Kristi S.

    2016-08-01

    There is a growing appreciation for the functional role of matrix mechanics in regulating stem cell self-renewal and differentiation processes. However, it is largely unknown how subcellular, spatial mechanical variations in the local extracellular environment mediate intracellular signal transduction and direct cell fate. Here, the effect of spatial distribution, magnitude, and organization of subcellular matrix mechanical properties on human mesenchymal stem cell (hMSCs) function was investigated. Exploiting a photodegradation reaction, a hydrogel cell culture substrate was fabricated with regions of spatially varied and distinct mechanical properties, which were subsequently mapped and quantified by atomic force microscopy (AFM). The variations in the underlying matrix mechanics were found to regulate cellular adhesion and transcriptional events. Highly spread, elongated morphologies and higher Yes-associated protein (YAP) activation were observed in hMSCs seeded on hydrogels with higher concentrations of stiff regions in a dose-dependent manner. However, when the spatial organization of the mechanically stiff regions was altered from a regular to randomized pattern, lower levels of YAP activation with smaller and more rounded cell morphologies were induced in hMSCs. We infer from these results that irregular, disorganized variations in matrix mechanics, compared with regular patterns, appear to disrupt actin organization, and lead to different cell fates; this was verified by observations of lower alkaline phosphatase (ALP) activity and higher expression of CD105, a stem cell marker, in hMSCs in random versus regular patterns of mechanical properties. Collectively, this material platform has allowed innovative experiments to elucidate a novel spatial mechanical dosing mechanism that correlates to both the magnitude and organization of spatial stiffness.

  18. Spatially patterned matrix elasticity directs stem cell fate

    PubMed Central

    Yang, Chun; DelRio, Frank W.; Ma, Hao; Killaars, Anouk R.; Basta, Lena P.; Kyburz, Kyle A.; Anseth, Kristi S.

    2016-01-01

    There is a growing appreciation for the functional role of matrix mechanics in regulating stem cell self-renewal and differentiation processes. However, it is largely unknown how subcellular, spatial mechanical variations in the local extracellular environment mediate intracellular signal transduction and direct cell fate. Here, the effect of spatial distribution, magnitude, and organization of subcellular matrix mechanical properties on human mesenchymal stem cell (hMSCs) function was investigated. Exploiting a photodegradation reaction, a hydrogel cell culture substrate was fabricated with regions of spatially varied and distinct mechanical properties, which were subsequently mapped and quantified by atomic force microscopy (AFM). The variations in the underlying matrix mechanics were found to regulate cellular adhesion and transcriptional events. Highly spread, elongated morphologies and higher Yes-associated protein (YAP) activation were observed in hMSCs seeded on hydrogels with higher concentrations of stiff regions in a dose-dependent manner. However, when the spatial organization of the mechanically stiff regions was altered from a regular to randomized pattern, lower levels of YAP activation with smaller and more rounded cell morphologies were induced in hMSCs. We infer from these results that irregular, disorganized variations in matrix mechanics, compared with regular patterns, appear to disrupt actin organization, and lead to different cell fates; this was verified by observations of lower alkaline phosphatase (ALP) activity and higher expression of CD105, a stem cell marker, in hMSCs in random versus regular patterns of mechanical properties. Collectively, this material platform has allowed innovative experiments to elucidate a novel spatial mechanical dosing mechanism that correlates to both the magnitude and organization of spatial stiffness. PMID:27436901

  19. Reprogramming of avian neural crest axial identity and cell fate.

    PubMed

    Simoes-Costa, Marcos; Bronner, Marianne E

    2016-06-24

    Neural crest populations along the embryonic body axis of vertebrates differ in developmental potential and fate, so that only the cranial neural crest can contribute to the craniofacial skeleton in vivo. We explored the regulatory program that imbues the cranial crest with its specialized features. Using axial-level specific enhancers to isolate and perform genome-wide profiling of the cranial versus trunk neural crest in chick embryos, we identified and characterized regulatory relationships between a set of cranial-specific transcription factors. Introducing components of this circuit into neural crest cells of the trunk alters their identity and endows these cells with the ability to give rise to chondroblasts in vivo. Our results demonstrate that gene regulatory circuits that support the formation of particular neural crest derivatives may be used to reprogram specific neural crest-derived cell types. PMID:27339986

  20. Nanoengineered Platforms to Guide Pluripotent Stem Cell Fate

    PubMed Central

    Rutledge, Katy; Jabbarzadeh, Ehsan

    2016-01-01

    Tissue engineering utilizes cells, signaling molecules, and scaffolds towards creating functional tissue to repair damaged organs. Pluripotent stem cells (PSCs) are a promising cell source due to their ability to self-renewal indefinitely and their potential to differentiate into almost any cell type. Great strides have been taken to parse the physiological mechanisms by which PSCs respond to their microenvironment and commit to a specific lineage. The combination of physical cues and chemical factors is thought to have the most profound influence on stem cell behavior, therefore a major focus of tissue engineering strategies is scaffold design to incorporate these signals. One overlooked component of the in vivo microenvironment researchers attempt to recapitulate with three dimensional (3D) substrates is the nanoarchitecture formed by the fibrillar network of extracellular matrix (ECM) proteins. These nanoscale features have the ability to impact cell adhesion, migration, proliferation, and lineage commitment. Significant advances have been made in deciphering how these nanoscale cues interact with stem cells to determine phenotype, but much is still unknown as to how the interplay between physical and chemical signals regulate in vitro and in vivo cellular fate. This review dives deeper to investigate nanoscale platforms for engineering tissue, as well use the use of these nanotechnologies to drive pluripotent stem cell lineage determination. PMID:26918198

  1. Three's company: regulation of cell fate by statins.

    PubMed

    Vamvakopoulos, Joannis E

    2005-04-01

    Inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase (statins), the rate-limiting enzyme of the mevalonate biosynthetic pathway, are currently the leading prescription drugs worldwide. Programmed cell death (apoptosis) is a powerful physiological regulator of cellular development, function and dynamics. Statins are known to induce cellular apoptosis in vitro; however, the clinical relevance of this action remains controversial. This paper draws from 15 years' worth of research to explore the impact of statin treatment on cell fate, as represented by the interlinked processes of cellular growth, differentiation and apoptosis. In particular, I outline our current understanding of the pertinent molecular mechanisms; and discuss the evidence for clinical relevance of statin-induced apoptosis.

  2. Advances in Understanding Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface

    NASA Astrophysics Data System (ADS)

    Karapanagioti, H. K.; Werner, D.; Werth, C.

    2012-04-01

    The results of a call for a special issue that is now in press by the Journal of Contaminant Hydrology will be presented. This special issue is edited by the authors and is entitled "Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface". A short abstract of each paper will be presented along with the most interesting results. Nine papers were accepted. Pollutants studied include: biocolloids, metals (arsenic, chromium, nickel), organic compounds such as hydrocarbons, chlorinated hydrocarbons, micropollutants (PAHs, PCBs), pesticides (glyphosate, 2,4-D). Findings presented in the papers include a modified batch reactor system to study equilibrium-reactive transport problems of metals. Column studies along with theoretical approximations evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three biocolloids. A polluted sediment remediation method is evaluated considering site-specific conditions through monitoring results and modelling. A field study points to glogging and also sorption as mechanisms affecting the effectiveness of sub-surface flow constructed wetlands. A new isotherm model combining modified traditionally used isotherms is proposed that can be used to simulate pH-dependent metal adsorption. Linear free energy relationships (LFERs) demonstrate ability to predict slight isotope shifts into the groundwater due to sorption. Possible modifications that improve the reliability of kinetic models and parameter values during the evaluation of experiments that assess the sorption of pesticides on soils are tested. Challenges in selecting groundwater pollutant fate and transport models that account for the effect of grain-scale sorption rate limitations are evaluated based on experimental results and are discussed based on the Damköhler number. Finally, a thorough review paper presents the impact of mineral micropores on the transport and fate of

  3. SCARECROW, SCR-LIKE 23 and SHORT-ROOT control bundle sheath cell fate and function in Arabidopsis thaliana.

    PubMed

    Cui, Hongchang; Kong, Danyu; Liu, Xiuwen; Hao, Yueling

    2014-04-01

    Bundle sheath (BS) cells form a single cell layer surrounding the vascular tissue in leaves. In C3 plants, photosynthesis occurs in both the BS and mesophyll cells, but the BS cells are the major sites of photosynthesis in C4 plants, whereas the mesophyll cells are only involved in CO2 fixation. Because C4 plants are more efficient photosynthetically, introduction of the C4 mechanism into C3 plants is considered a key strategy to improve crop yield. One prerequisite for such C3-to-C4 engineering is the ability to manipulate the number and physiology of the BS cells, but the molecular basis of BS cell-fate specification remains unclear. Here we report that mutations in three GRAS family transcription factors, SHORT-ROOT (SHR), SCARECROW (SCR) and SCARECROW-LIKE 23 (SCL23), affect BS cell fate in Arabidopsis thaliana. SCR and SCL23 are expressed specifically in the BS cells and act redundantly in BS cell-fate specification, but their expression pattern and function diverge at later stages of leaf development. Using ChIP-chip experiments and sugar assays, we show that SCR is primarily involved in sugar transport whereas SCL23 functions in mineral transport. SHR is also essential for BS cell-fate specification, but it is expressed in the central vascular tissue. However, the SHR protein moves into the BS cells, where it directly regulates SCR and SCL23 expression. SHR, SCR and SCL23 homologs are present in many plant species, suggesting that this developmental pathway for BS cell-fate specification is likely to be evolutionarily conserved.

  4. Magnetic resonance imaging of transplanted stem cell fate in stroke

    PubMed Central

    Aghayan, Hamid Reza; Soleimani, Masoud; Goodarzi, Parisa; Norouzi-Javidan, Abbas; Emami-Razavi, Seyed Hasan; Larijani, Bagher; Arjmand, Babak

    2014-01-01

    Nowadays, scientific findings in the field of regeneration of nervous system have revealed the possibility of stem cell based therapies for damaged brain tissue related disorders like stroke. Furthermore, to achieve desirable outcomes from cellular therapies, one needs to monitor the migration, engraftment, viability, and also functional fate of transplanted stem cells. Magnetic resonance imaging is an extremely versatile technique for this purpose, which has been broadly used to study stroke and assessment of therapeutic role of stem cells. In this review we searched in PubMed search engine by using following keywords; “Stem Cells”, “Cell Tracking”, “Stroke”, “Stem Cell Transplantation”, “Nanoparticles”, and “Magnetic Resonance Imaging” as entry terms and based on the mentioned key words, the search period was set from 1976 to 2012. The main purpose of this article is describing various advantages of molecular and magnetic resonance imaging of stem cells, with focus on translation of stem cell research to clinical research. PMID:25097631

  5. An exquisite cross-control mechanism among endothelial cell fate regulators directs the plasticity and heterogeneity of lymphatic endothelial cells

    PubMed Central

    Kang, Jinjoo; Yoo, Jaehyuk; Lee, Sunju; Tang, Wanli; Aguilar, Berenice; Ramu, Swapnika; Choi, Inho; Otu, Hasan H.; Shin, Jay W.; Dotto, G. Paolo; Koh, Chester J.; Detmar, Michael

    2010-01-01

    Arteriovenous-lymphatic endothelial cell fates are specified by the master regulators, namely, Notch, COUP-TFII, and Prox1. Whereas Notch is expressed in the arteries and COUP-TFII in the veins, the lymphatics express all 3 cell fate regulators. Previous studies show that lymphatic endothelial cell (LEC) fate is highly plastic and reversible, raising a new concept that all 3 endothelial cell fates may coreside in LECs and a subtle alteration can result in a reprogramming of LEC fate. We provide a molecular basis verifying this concept by identifying a cross-control mechanism among these cell fate regulators. We found that Notch signal down-regulates Prox1 and COUP-TFII through Hey1 and Hey2 and that activated Notch receptor suppresses the lymphatic phenotypes and induces the arterial cell fate. On the contrary, Prox1 and COUP-TFII attenuate vascular endothelial growth factor signaling, known to induce Notch, by repressing vascular endothelial growth factor receptor-2 and neuropilin-1. We show that previously reported podoplanin-based LEC heterogeneity is associated with differential expression of Notch1 in human cutaneous lymphatics. We propose that the expression of the 3 cell fate regulators is controlled by an exquisite feedback mechanism working in LECs and that LEC fate is a consequence of the Prox1-directed lymphatic equilibrium among the cell fate regulators. PMID:20351309

  6. Power-Law Modeling of Cancer Cell Fates Driven by Signaling Data to Reveal Drug Effects

    PubMed Central

    Zhang, Fan; Wu, Min; Kwoh, Chee Keong; Zheng, Jie

    2016-01-01

    Extracellular signals are captured and transmitted by signaling proteins inside a cell. An important type of cellular responses to the signals is the cell fate decision, e.g., apoptosis. However, the underlying mechanisms of cell fate regulation are still unclear, thus comprehensive and detailed kinetic models are not yet available. Alternatively, data-driven models are promising to bridge signaling data with the phenotypic measurements of cell fates. The traditional linear model for data-driven modeling of signaling pathways has its limitations because it assumes that the a cell fate is proportional to the activities of signaling proteins, which is unlikely in the complex biological systems. Therefore, we propose a power-law model to relate the activities of all the measured signaling proteins to the probabilities of cell fates. In our experiments, we compared our nonlinear power-law model with the linear model on three cancer datasets with phosphoproteomics and cell fate measurements, which demonstrated that the nonlinear model has superior performance on cell fates prediction. By in silico simulation of virtual protein knock-down, the proposed model is able to reveal drug effects which can complement traditional approaches such as binding affinity analysis. Moreover, our model is able to capture cell line specific information to distinguish one cell line from another in cell fate prediction. Our results show that the power-law data-driven model is able to perform better in cell fate prediction and provide more insights into the signaling pathways for cancer cell fates than the linear model. PMID:27764199

  7. Time-variant clustering model for understanding cell fate decisions.

    PubMed

    Huang, Wei; Cao, Xiaoyi; Biase, Fernando H; Yu, Pengfei; Zhong, Sheng

    2014-11-01

    Both spatial characteristics and temporal features are often the subjects of concern in physical, social, and biological studies. This work tackles the clustering problems for time course data in which the cluster number and clustering structure change with respect to time, dubbed time-variant clustering. We developed a hierarchical model that simultaneously clusters the objects at every time point and describes the relationships of the clusters between time points. The hidden layer of this model is a generalized form of branching processes. A reversible-jump Markov Chain Monte Carlo method was implemented for model inference, and a feature selection procedure was developed. We applied this method to explore an open question in preimplantation embryonic development. Our analyses using single-cell gene expression data suggested that the earliest cell fate decision could start at the 4-cell stage in mice, earlier than the commonly thought 8- to 16-cell stage. These results together with independent experimental data from single-cell RNA-seq provided support against a prevailing hypothesis in mammalian development. PMID:25339442

  8. Time-variant clustering model for understanding cell fate decisions

    PubMed Central

    Huang, Wei; Cao, Xiaoyi; Biase, Fernando H.; Yu, Pengfei; Zhong, Sheng

    2014-01-01

    Both spatial characteristics and temporal features are often the subjects of concern in physical, social, and biological studies. This work tackles the clustering problems for time course data in which the cluster number and clustering structure change with respect to time, dubbed time-variant clustering. We developed a hierarchical model that simultaneously clusters the objects at every time point and describes the relationships of the clusters between time points. The hidden layer of this model is a generalized form of branching processes. A reversible-jump Markov Chain Monte Carlo method was implemented for model inference, and a feature selection procedure was developed. We applied this method to explore an open question in preimplantation embryonic development. Our analyses using single-cell gene expression data suggested that the earliest cell fate decision could start at the 4-cell stage in mice, earlier than the commonly thought 8- to 16-cell stage. These results together with independent experimental data from single-cell RNA-seq provided support against a prevailing hypothesis in mammalian development. PMID:25339442

  9. Nanomaterials for regulating cancer and stem cell fate

    NASA Astrophysics Data System (ADS)

    Shah, Birju P.

    The realm of nanomedicine has grown exponentially over the past few decades. However, there are several obstacles that need to be overcome, prior to the wide-spread clinical applications of these nanoparticles, such as (i) developing well-defined nanoparticles of varying size, morphology and composition to enable various clinical applications; (ii) overcome various physiological barriers encountered in order to deliver the therapeutics to the target location; and (iii) real-time monitoring of the nano-therapeutics within the human body for tracking their uptake, localization and effect. Hence, this dissertation focuses on developing multimodal nanotechnology-based approaches to overcome the above-mentioned challenges and thus enable regulation of cancer and stem cell fate. The initial part of this dissertation describes the development of multimodal magnetic core-shell nanoparticles (MCNPs), comprised of a highly magnetic core surrounded by a thin gold shell, thus combining magnetic and plasmonic properties. These nanoparticles were utilized for mainly two applications: (i) Magnetically-facilitated delivery of siRNA and plasmid DNA for effective stem cell differentiation and imaging and (ii) Combined hyperthermia and targeted delivery of a mitochondria-targeting peptide for enhancing apoptosis in cancer cells. The following part of this dissertation presents the generation of a multi-functional cyclodextrin-conjugated polymeric delivery platform (known as DexAMs), for co-delivery of anticancer drugs and siRNAs in a target-specific manner to brain tumor cells. This combined delivery of chemotherapeutics and siRNA resulted in a synergistic effect on the apoptosis of brain tumor cells, as compared to the individual treatments. The final part of this thesis presents development of stimuli-responsive uorescence resonance energy transfer (FRET)-based mesoporous silica nanoparticles for real-time monitoring of drug release in cells. The stimuli-responsive behavior of

  10. Modeling Cell–Cell Interactions in Regulating Multiple Myeloma Initiating Cell Fate

    PubMed Central

    Peng, Tao; Peng, Huiming; Choi, Dong Soon; Su, Jing; (Jeff) Chang, Chung-Che

    2014-01-01

    Cancer initiating cells have been documented in multiple myeloma and believed to be a key factor that initiates and drives tumor growth, differentiation, metastasis, and recurrence of the diseases. Although myeloma initiating cells (MICs) are likely to share many properties of normal stem cells, the underlying mechanisms regulating the fate of MICs are largely unknown. Studies designed to explore such communication are urgently needed to enhance our ability to predict the fate decisions of MICs (self-renewal, differentiation, and proliferation). In this study, we developed a novel system to understand the intercellular communication between MICs and their niche by seamlessly integrating experimental data and mathematical model. We first designed dynamic cell culture experiments and collected three types of cells (side population cells, progenitor cells, and mature myeloma cells) under various cultural conditions with flow cytometry. Then we developed a lineage model with ordinary differential equations by considering secreted factors, self-renewal, differentiation, and other biological functions of those cells, to model the cell–cell interactions among the three cell types. Particle swarm optimization was employed to estimate the model parameters by fitting the experimental data to the lineage model. The theoretical results show that the correlation coefficient analysis can reflect the feedback loops among the three cell types, the intercellular feedback signaling can regulate cell population dynamics, and the culture strategies can decide cell growth. This study provides a basic framework of studying cell–cell interactions in regulating MICs fate. PMID:24058033

  11. SOX17 is a critical specifier of human primordial germ cell fate.

    PubMed

    Irie, Naoko; Weinberger, Leehee; Tang, Walfred W C; Kobayashi, Toshihiro; Viukov, Sergey; Manor, Yair S; Dietmann, Sabine; Hanna, Jacob H; Surani, M Azim

    2015-01-15

    Specification of primordial germ cells (PGCs) marks the beginning of the totipotent state. However, without a tractable experimental model, the mechanism of human PGC (hPGC) specification remains unclear. Here, we demonstrate specification of hPGC-like cells (hPGCLCs) from germline competent pluripotent stem cells. The characteristics of hPGCLCs are consistent with the embryonic hPGCs and a germline seminoma that share a CD38 cell-surface marker, which collectively defines likely progression of the early human germline. Remarkably, SOX17 is the key regulator of hPGC-like fate, whereas BLIMP1 represses endodermal and other somatic genes during specification of hPGCLCs. Notable mechanistic differences between mouse and human PGC specification could be attributed to their divergent embryonic development and pluripotent states, which might affect other early cell-fate decisions. We have established a foundation for future studies on resetting of the epigenome in hPGCLCs and hPGCs for totipotency and the transmission of genetic and epigenetic information. PMID:25543152

  12. Genetic Regulation of Fate Decisions in Therapeutic T Cells to Enhance Tumor Protection and Memory Formation.

    PubMed

    Veliça, Pedro; Zech, Mathias; Henson, Sian; Holler, Angelika; Manzo, Teresa; Pike, Rebecca; Santos E Sousa, Pedro; Zhang, Lei; Heinz, Niels; Schiedlmeier, Bernhard; Pule, Martin; Stauss, Hans; Chakraverty, Ronjon

    2015-07-01

    A key challenge in the field of T-cell immunotherapy for cancer is creating a suitable platform for promoting differentiation of effector cells while at the same time enabling self-renewal needed for long-term memory. Although transfer of less differentiated memory T cells increases efficacy through greater expansion and persistence in vivo, the capacity of such cells to sustain effector functions within immunosuppressive tumor microenvironments may still be limiting. We have therefore directly compared the impact of effector versus memory differentiation of therapeutic T cells in tumor-bearing mice by introducing molecular switches that regulate cell fate decisions via mTOR. Ectopic expression of RAS homolog enriched in brain (RHEB) increased mTORC1 signaling, promoted a switch to aerobic glycolysis, and increased expansion of effector T cells. By rapidly infiltrating tumors, RHEB-transduced T cells significantly reduced the emergence of immunoedited escape variants. In contrast, expression of proline-rich Akt substrate of 40 kDa (PRAS40) inhibited mTORC1, promoted quiescence, and blocked tumor infiltration. Fate mapping studies following transient expression of PRAS40 demonstrated that mTORC1(low) T cells made no contribution to initial tumor control but instead survived to become memory cells proficient in generating recall immunity. Our data support the design of translational strategies for generating heterogeneous T-cell immunity against cancer, with the appropriate balance between promoting effector differentiation and self-renewal. Unlike pharmacologic inhibitors, the genetic approach described here allows for upregulation as well as inhibition of the mTORC1 pathway and is highly selective for the therapeutic T cells without affecting systemic mTORC1 functions.

  13. Cell fate reprogramming by control of intracellular network dynamics

    NASA Astrophysics Data System (ADS)

    Zanudo, Jorge G. T.; Albert, Reka

    Identifying control strategies for biological networks is paramount for practical applications that involve reprogramming a cell's fate, such as disease therapeutics and stem cell reprogramming. Although the topic of controlling the dynamics of a system has a long history in control theory, most of this work is not directly applicable to intracellular networks. Here we present a network control method that integrates the structural and functional information available for intracellular networks to predict control targets. Formulated in a logical dynamic scheme, our control method takes advantage of certain function-dependent network components and their relation to steady states in order to identify control targets, which are guaranteed to drive any initial state to the target state with 100% effectiveness and need to be applied only transiently for the system to reach and stay in the desired state. We illustrate our method's potential to find intervention targets for cancer treatment and cell differentiation by applying it to a leukemia signaling network and to the network controlling the differentiation of T cells. We find that the predicted control targets are effective in a broad dynamic framework. Moreover, several of the predicted interventions are supported by experiments. This work was supported by NSF Grant PHY 1205840.

  14. Mechanical memory and dosing influence stem cell fate

    NASA Astrophysics Data System (ADS)

    Yang, Chun; Tibbitt, Mark W.; Basta, Lena; Anseth, Kristi S.

    2014-06-01

    We investigated whether stem cells remember past physical signals and whether these can be exploited to dose cells mechanically. We found that the activation of the Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding domain (TAZ) as well as the pre-osteogenic transcription factor RUNX2 in human mesenchymal stem cells (hMSCs) cultured on soft poly(ethylene glycol) (PEG) hydrogels (Young’s modulus E ~ 2 kPa) depended on previous culture time on stiff tissue culture polystyrene (TCPS; E ~ 3 GPa). In addition, mechanical dosing of hMSCs cultured on initially stiff (E ~ 10 kPa) and then soft (E ~ 2 kPa) phototunable PEG hydrogels resulted in either reversible or—above a threshold mechanical dose—irreversible activation of YAP/TAZ and RUNX2. We also found that increased mechanical dosing on supraphysiologically stiff TCPS biases hMSCs towards osteogenic differentiation. We conclude that stem cells possess mechanical memory—with YAP/TAZ acting as an intracellular mechanical rheostat—that stores information from past physical environments and influences the cells’ fate.

  15. Mitophagy-driven mitochondrial rejuvenation regulates stem cell fate

    PubMed Central

    Vazquez-Martin, Alejandro; Van den Haute, Chris; Cufí, Sílvia; Corominas-Faja, Bruna; Cuyàs, Elisabet; Lopez-Bonet, Eugeni; Rodriguez-Gallego, Esther; Fernández-Arroyo, Salvador; Joven, Jorge; Baekelandt, Veerle; Menendez, Javier A.

    2016-01-01

    Our understanding on how selective mitochondrial autophagy, or mitophagy, can sustain the archetypal properties of stem cells is incomplete. PTEN-induced putative kinase 1 (PINK1) plays a key role in the maintenance of mitochondrial morphology and function and in the selective degradation of damaged mitochondria by mitophagy. Here, using embryonic fibroblasts from PINK1 gene-knockout (KO) mice, we evaluated whether mitophagy is a causal mechanism for the control of cell-fate plasticity and maintenance of pluripotency. Loss of PINK1-dependent mitophagy was sufficient to dramatically decrease the speed and efficiency of induced pluripotent stem cell (iPSC) reprogramming. Mitophagy-deficient iPSC colonies, which were characterized by a mixture of mature and immature mitochondria, seemed unstable, with a strong tendency to spontaneously differentiate and form heterogeneous populations of cells. Although mitophagy-deficient iPSC colonies normally expressed pluripotent markers, functional monitoring of cellular bioenergetics revealed an attenuated glycolysis in mitophagy-deficient iPSC cells. Targeted metabolomics showed a notable alteration in numerous glycolysis- and TCA-related metabolites in mitophagy-deficient iPSC cells, including a significant decrease in the intracellular levels of α-ketoglutarate -a key suppressor of the differentiation path in stem cells. Mitophagy-deficient iPSC colonies exhibited a notably reduced teratoma-initiating capacity, but fully retained their pluripotency and multi-germ layer differentiation capacity in vivo. PINK1-dependent mitophagy pathway is an important mitochondrial switch that determines the efficiency and quality of somatic reprogramming. Mitophagy-driven mitochondrial rejuvenation might contribute to the ability of iPSCs to suppress differentiation by directing bioenergetic transition and metabolome remodeling traits. These findings provide new insights into how mitophagy might influence the stem cell decisions to retain

  16. Mitophagy-driven mitochondrial rejuvenation regulates stem cell fate.

    PubMed

    Vazquez-Martin, Alejandro; Van den Haute, Chris; Cufí, Sílvia; Corominas-Faja, Bruna; Cuyàs, Elisabet; Lopez-Bonet, Eugeni; Rodriguez-Gallego, Esther; Fernández-Arroyo, Salvador; Joven, Jorge; Baekelandt, Veerle; Menendez, Javier A

    2016-07-01

    Our understanding on how selective mitochondrial autophagy, or mitophagy, can sustain the archetypal properties of stem cells is incomplete. PTEN-induced putative kinase 1 (PINK1) plays a key role in the maintenance of mitochondrial morphology and function and in the selective degradation of damaged mitochondria by mitophagy. Here, using embryonic fibroblasts fromPINK1 gene-knockout (KO) mice, we evaluated whether mitophagy is a causal mechanism for the control of cell-fate plasticity and maintenance of pluripotency. Loss of PINK1-dependent mitophagy was sufficient to dramatically decrease the speed and efficiency of induced pluripotent stem cell (iPSC) reprogramming. Mitophagy-deficient iPSC colonies, which were characterized by a mixture of mature and immature mitochondria, seemed unstable, with a strong tendency to spontaneously differentiate and form heterogeneous populations of cells. Although mitophagy-deficient iPSC colonies normally expressed pluripotent markers, functional monitoring of cellular bioenergetics revealed an attenuated glycolysis in mitophagy-deficient iPSC cells. Targeted metabolomics showed a notable alteration in numerous glycolysis- and TCA-related metabolites in mitophagy-deficient iPSC cells, including a significant decrease in the intracellular levels of α-ketoglutarate -a key suppressor of the differentiation path in stem cells. Mitophagy-deficient iPSC colonies exhibited a notably reduced teratoma-initiating capacity, but fully retained their pluripotency and multi-germ layer differentiation capacity in vivo. PINK1-dependent mitophagy pathway is an important mitochondrial switch that determines the efficiency and quality of somatic reprogramming. Mitophagy-driven mitochondrial rejuvenation might contribute to the ability of iPSCs to suppress differentiation by directing bioenergetic transition and metabolome remodeling traits. These findings provide new insights into how mitophagy might influence the stem cell decisions to retain

  17. EBI2 augments Tfh cell fate by promoting interaction with IL-2-quenching dendritic cells.

    PubMed

    Li, Jianhua; Lu, Erick; Yi, Tangsheng; Cyster, Jason G

    2016-05-01

    T follicular helper (Tfh) cells are a subset of T cells carrying the CD4 antigen; they are important in supporting plasma cell and germinal centre responses. The initial induction of Tfh cell properties occurs within the first few days after activation by antigen recognition on dendritic cells, although how dendritic cells promote this cell-fate decision is not fully understood. Moreover, although Tfh cells are uniquely defined by expression of the follicle-homing receptor CXCR5 (refs 1, 2), the guidance receptor promoting the earlier localization of activated T cells at the interface of the B-cell follicle and T zone has been unclear. Here we show that the G-protein-coupled receptor EBI2 (GPR183) and its ligand 7α,25-dihydroxycholesterol mediate positioning of activated CD4 T cells at the interface of the follicle and T zone. In this location they interact with activated dendritic cells and are exposed to Tfh-cell-promoting inducible co-stimulator (ICOS) ligand. Interleukin-2 (IL-2) is a cytokine that has multiple influences on T-cell fate, including negative regulation of Tfh cell differentiation. We demonstrate that activated dendritic cells in the outer T zone further augment Tfh cell differentiation by producing membrane and soluble forms of CD25, the IL-2 receptor α-chain, and quenching T-cell-derived IL-2. Mice lacking EBI2 in T cells or CD25 in dendritic cells have reduced Tfh cells and mount defective T-cell-dependent plasma cell and germinal centre responses. These findings demonstrate that distinct niches within the lymphoid organ T zone support distinct cell fate decisions, and they establish a function for dendritic-cell-derived CD25 in controlling IL-2 availability and T-cell differentiation.

  18. How the cell cycle impacts chromatin architecture and influences cell fate

    PubMed Central

    Ma, Yiqin; Kanakousaki, Kiriaki; Buttitta, Laura

    2015-01-01

    Since the earliest observations of cells undergoing mitosis, it has been clear that there is an intimate relationship between the cell cycle and nuclear chromatin architecture. The nuclear envelope and chromatin undergo robust assembly and disassembly during the cell cycle, and transcriptional and post-transcriptional regulation of histone biogenesis and chromatin modification is controlled in a cell cycle-dependent manner. Chromatin binding proteins and chromatin modifications in turn influence the expression of critical cell cycle regulators, the accessibility of origins for DNA replication, DNA repair, and cell fate. In this review we aim to provide an integrated discussion of how the cell cycle machinery impacts nuclear architecture and vice-versa. We highlight recent advances in understanding cell cycle-dependent histone biogenesis and histone modification deposition, how cell cycle regulators control histone modifier activities, the contribution of chromatin modifications to origin firing for DNA replication, and newly identified roles for nucleoporins in regulating cell cycle gene expression, gene expression memory and differentiation. We close with a discussion of how cell cycle status may impact chromatin to influence cell fate decisions, under normal contexts of differentiation as well as in instances of cell fate reprogramming. PMID:25691891

  19. Microbe-associated immunomodulatory metabolites: Influence on T cell fate and function.

    PubMed

    Castro, C N; Freitag, J; Berod, L; Lochner, M; Sparwasser, T

    2015-12-01

    During the past two decades, a growing interest surrounding the interaction between microbe-associated molecular patterns (MAMPs) and pattern recognition receptors has occurred. This attention is now driven alongside bacterial-derived metabolites, which impact immune cell differentiation and function. Hence, this review introduces the term meta-MAMP as a means to classify the microbial derived-metabolites, which influence the immune response by affecting specific cellular processes. We discuss two prominent examples of meta-MAMPs: the first, rapamycin (isolated from Streptomyces), was discovered in the 1970s and since then has been thoroughly studied. The second, soraphen A (isolated from Myxobacteria), was discovered in the early 1990s but only recently identified as a promising immunomodulator. Both meta-MAMPs are similar in their remarkable capacity to modulate T cell fate by targeting key metabolic pathways triggered upon T cell activation. In this context, we highlight the progress made in the field of immunometabolism and the possibility of modulating metabolic pathways such as cellular fatty acid metabolism as a strategy for immunomodulation. We focus on the use of microbial metabolites as auspicious agents for T cell fate modulation.

  20. Putting things in place for fertilization: discovering roles for importin proteins in cell fate and spermatogenesis

    PubMed Central

    Loveland, Kate L; Major, Andrew T; Butler, Romaly; Young, Julia C; Jans, David A; Miyamoto, Yoichi

    2015-01-01

    Importin proteins were originally characterized for their central role in protein transport through the nuclear pores, the only intracellular entry to the nucleus. This vital function must be tightly regulated to control access by transcription factors and other nuclear proteins to genomic DNA, to achieve appropriate modulation of cellular behaviors affecting cell fate. Importin-mediated nucleocytoplasmic transport relies on their specific recognition of cargoes, with each importin binding to distinct and overlapping protein subsets. Knowledge of importin function has expanded substantially in regard to three key developmental systems: embryonic stem cells, muscle cells and the germ line. In the decade since the potential for regulated nucleocytoplasmic transport to contribute to spermatogenesis was proposed, we and others have shown that the importins that ferry transcription factors into the nucleus perform additional roles, which control cell fate. This review presents key findings from studies of mammalian spermatogenesis that reveal potential new pathways by which male fertility and infertility arise. These studies of germline genesis illuminate new ways in which importin proteins govern cellular differentiation, including via directing proteins to distinct intracellular compartments and by determining cellular stress responses. PMID:25994647

  1. Microbe-associated immunomodulatory metabolites: Influence on T cell fate and function.

    PubMed

    Castro, C N; Freitag, J; Berod, L; Lochner, M; Sparwasser, T

    2015-12-01

    During the past two decades, a growing interest surrounding the interaction between microbe-associated molecular patterns (MAMPs) and pattern recognition receptors has occurred. This attention is now driven alongside bacterial-derived metabolites, which impact immune cell differentiation and function. Hence, this review introduces the term meta-MAMP as a means to classify the microbial derived-metabolites, which influence the immune response by affecting specific cellular processes. We discuss two prominent examples of meta-MAMPs: the first, rapamycin (isolated from Streptomyces), was discovered in the 1970s and since then has been thoroughly studied. The second, soraphen A (isolated from Myxobacteria), was discovered in the early 1990s but only recently identified as a promising immunomodulator. Both meta-MAMPs are similar in their remarkable capacity to modulate T cell fate by targeting key metabolic pathways triggered upon T cell activation. In this context, we highlight the progress made in the field of immunometabolism and the possibility of modulating metabolic pathways such as cellular fatty acid metabolism as a strategy for immunomodulation. We focus on the use of microbial metabolites as auspicious agents for T cell fate modulation. PMID:26320629

  2. Coupling transcriptional and post-transcriptional miRNA regulation in the control of cell fate

    PubMed Central

    Shalgi, Reut; Brosh, Ran; Oren, Moshe; Pilpel, Yitzhak; Rotter, Varda

    2009-01-01

    miRNAs function as a critical regulatory layer in development, differentiation, and the maintenance of cell fate. Depletion of miRNAs from embryonic stem cells impairs their differentiation capacity. Total elimination of miRNAs leads to premature senescence in normal cells and tissues through activation of the DNA-damage checkpoint, whereas ablation of miRNAs in cancer cell lines results in an opposite effect, enhancing their tumorigenic potential. Here we compile evidence from the literature that point at miRNAs as key players in the maintenance of genomic integrity and proper cell fate. There is an apparent gap between our understanding of the subtle way by which miRNAs modulate protein levels, and their profound impact on cell fate. We propose that examining miRNAs in the context of the regulatory transcriptional and post-transcriptional networks they are embedded in may provide a broader view of their role in controlling cell fate. PMID:20157565

  3. β-catenin-driven binary cell fate decisions in animal development.

    PubMed

    Bertrand, Vincent

    2016-01-01

    The Wnt/β-catenin pathway plays key roles during animal development. In several species, β-catenin is used in a reiterative manner to regulate cell fate diversification between daughter cells following division. This binary cell fate specification mechanism has been observed in animals that belong to very diverse phyla: the nematode Caenorhabditis elegans, the annelid Platynereis, and the ascidian Ciona. It may also play a role in the regulation of several stem cell lineages in vertebrates. While the molecular mechanism behind this binary cell fate switch is not fully understood, it appears that both secreted Wnt ligands and asymmetric cortical factors contribute to the generation of the difference in nuclear β-catenin levels between daughter cells. β-Catenin then cooperates with lineage specific transcription factors to induce the expression of novel sets of transcription factors at each round of divisions, thereby diversifying cell fate. For further resources related to this article, please visit the WIREs website. PMID:26952169

  4. Ablation of Coactivator Med1 Switches the Cell Fate of Dental Epithelia to That Generating Hair

    PubMed Central

    Nguyen, Thai; Sakai, Kiyoshi; He, Bing; Fong, Chak; Oda, Yuko

    2014-01-01

    Cell fates are determined by specific transcriptional programs. Here we provide evidence that the transcriptional coactivator, Mediator 1 (Med1), is essential for the cell fate determination of ectodermal epithelia. Conditional deletion of Med1 in vivo converted dental epithelia into epidermal epithelia, causing defects in enamel organ development while promoting hair formation in the incisors. We identified multiple processes by which hairs are generated in Med1 deficient incisors: 1) dental epithelial stem cells lacking Med 1 fail to commit to the dental lineage, 2) Sox2-expressing stem cells extend into the differentiation zone and remain multi-potent due to reduced Notch1 signaling, and 3) epidermal fate is induced by calcium as demonstrated in dental epithelial cell cultures. These results demonstrate that Med1 is a master regulator in adult stem cells to govern epithelial cell fate. PMID:24949995

  5. Notch regulation of myogenic versus endothelial fates of cells that migrate from the somite to the limb

    PubMed Central

    Mayeuf-Louchart, Alicia; Lagha, Mounia; Danckaert, Anne; Rocancourt, Didier; Relaix, Frederic; Vincent, Stéphane D.; Buckingham, Margaret

    2014-01-01

    Multipotent Pax3-positive (Pax3+) cells in the somites give rise to skeletal muscle and to cells of the vasculature. We had previously proposed that this cell-fate choice depends on the equilibrium between Pax3 and Foxc2 expression. In this study, we report that the Notch pathway promotes vascular versus skeletal muscle cell fates. Overactivating the Notch pathway specifically in Pax3+ progenitors, via a conditional Pax3NICD allele, results in an increase of the number of smooth muscle and endothelial cells contributing to the aorta. At limb level, Pax3+ cells in the somite give rise to skeletal muscles and to a subpopulation of endothelial cells in blood vessels of the limb. We now demonstrate that in addition to the inhibitory role of Notch signaling on skeletal muscle cell differentiation, the Notch pathway affects the Pax3:Foxc2 balance and promotes the endothelial versus myogenic cell fate, before migration to the limb, in multipotent Pax3+ cells in the somite of the mouse embryo. PMID:24927569

  6. Slit/Robo signaling regulates cell fate decisions in the intestinal stem cell lineage of Drosophila

    PubMed Central

    Biteau, Benoît; Jasper, Heinrich

    2014-01-01

    To maintain tissue homeostasis, cell fate decisions within stem cell lineages have to respond to the needs of the tissue. This coordination of lineage choices with regenerative demand remains poorly characterized. Here we identify a signal from enteroendocrine cells (EEs) that controls lineage specification in the Drosophila intestine. We find that EEs secrete Slit, a ligand for the Robo2 receptor in stem cells (ISCs) that limits ISC commitment to the endocrine lineage, establishing negative feedback control of EE regeneration. We further show that this lineage decision is made within ISCs and requires induction of the transcription factor Prospero in ISCs. Our work identifies a new function for the conserved Slit/Robo pathway in the regulation of adult stem cells, establishing negative feedback control of ISC lineage specification as a critical strategy to preserve tissue homeostasis. Our results further amend the current understanding of cell fate commitment within the Drosophila ISC lineage. PMID:24931602

  7. Slit/Robo signaling regulates cell fate decisions in the intestinal stem cell lineage of Drosophila.

    PubMed

    Biteau, Benoît; Jasper, Heinrich

    2014-06-26

    In order to maintain tissue homeostasis, cell fate decisions within stem cell lineages have to respond to the needs of the tissue. This coordination of lineage choices with regenerative demand remains poorly characterized. Here, we identify a signal from enteroendocrine cells (EEs) that controls lineage specification in the Drosophila intestine. We find that EEs secrete Slit, a ligand for the Robo2 receptor in intestinal stem cells (ISCs) that limits ISC commitment to the endocrine lineage, establishing negative feedback control of EE regeneration. Furthermore, we show that this lineage decision is made within ISCs and requires induction of the transcription factor Prospero in ISCs. Our work identifies a function for the conserved Slit/Robo pathway in the regulation of adult stem cells, establishing negative feedback control of ISC lineage specification as a critical strategy to preserve tissue homeostasis. Our results further amend the current understanding of cell fate commitment within the Drosophila ISC lineage. PMID:24931602

  8. Slit/Robo signaling regulates cell fate decisions in the intestinal stem cell lineage of Drosophila.

    PubMed

    Biteau, Benoît; Jasper, Heinrich

    2014-06-26

    In order to maintain tissue homeostasis, cell fate decisions within stem cell lineages have to respond to the needs of the tissue. This coordination of lineage choices with regenerative demand remains poorly characterized. Here, we identify a signal from enteroendocrine cells (EEs) that controls lineage specification in the Drosophila intestine. We find that EEs secrete Slit, a ligand for the Robo2 receptor in intestinal stem cells (ISCs) that limits ISC commitment to the endocrine lineage, establishing negative feedback control of EE regeneration. Furthermore, we show that this lineage decision is made within ISCs and requires induction of the transcription factor Prospero in ISCs. Our work identifies a function for the conserved Slit/Robo pathway in the regulation of adult stem cells, establishing negative feedback control of ISC lineage specification as a critical strategy to preserve tissue homeostasis. Our results further amend the current understanding of cell fate commitment within the Drosophila ISC lineage.

  9. Basic helix-loop-helix transcription factors and epidermal cell fate determination in Arabidopsis

    PubMed Central

    Zhao, Hongtao; Li, Xia; Ma, Ligeng

    2012-01-01

    Cell fate determination is an important process in multicellular organisms. Plant epidermis is a readily-accessible, well-used model for the study of cell fate determination. Our knowledge of cell fate determination is growing steadily due to genetic and molecular analyses of root hairs, trichomes, and stomata, which are derived from the epidermal cells of roots and aerial tissues. Studies have shown that a large number of factors are involved in the establishment of these cell types, especially members of the basic helix-loop-helix (bHLH) superfamily, which is an important family of transcription factors. In this mini-review, we focus on the role of bHLH transcription factors in cell fate determination in Arabidopsis. PMID:23073001

  10. Activation-induced B cell fates are selected by intracellular stochastic competition.

    PubMed

    Duffy, Ken R; Wellard, Cameron J; Markham, John F; Zhou, Jie H S; Holmberg, Ross; Hawkins, Edwin D; Hasbold, Jhagvaral; Dowling, Mark R; Hodgkin, Philip D

    2012-01-20

    In response to stimulation, B lymphocytes pursue a large number of distinct fates important for immune regulation. Whether each cell's fate is determined by external direction, internal stochastic processes, or directed asymmetric division is unknown. Measurement of times to isotype switch, to develop into a plasmablast, and to divide or to die for thousands of cells indicated that each fate is pursued autonomously and stochastically. As a consequence of competition between these processes, censorship of alternative outcomes predicts intricate correlations that are observed in the data. Stochastic competition can explain how the allocation of a proportion of B cells to each cell fate is achieved. The B cell may exemplify how other complex cell differentiation systems are controlled. PMID:22223740

  11. M-CSF instructs myeloid lineage fate in single haematopoietic stem cells

    PubMed Central

    Mossadegh-Keller, Noushine; Sarrazin, Sandrine; Kandalla, Prashanth K.; Espinosa, Leon; Stanley, E. Richard; Nutt, Stephen L.; Moore, Jordan; Sieweke, Michael H.

    2013-01-01

    Under stress conditions such as infection or inflammation the body rapidly needs to generate new blood cells that are adapted to the challenge. Haematopoietic cytokines are known to increase output of specific mature cells by affecting survival, expansion and differentiation of lineage-committed progenitors1,2, but it has been debated whether long-term haematopoietic stem cells (HSCs) are susceptible to direct lineage-specifying effects of cytokines. Although genetic changes in transcription factor balance can sensitize HSCs to cytokine instruction3, the initiation of HSC commitment is generally thought to be triggered by stochastic fluctuation in cell-intrinsic regulators such as lineage-specific transcription factors4–7, leaving cytokines to ensure survival and proliferation of the progeny cells8,9. Here we show that macrophage colony-stimulating factor (M-CSF, also called CSF1), a myeloid cytokine released during infection and inflammation, can directly induce the myeloid master regulator PU.1 and instruct myeloid cell-fate change in mouse HSCs, independently of selective survival or proliferation. Video imaging and single-cell gene expression analysis revealed that stimulation of highly purified HSCs with M-CSF in culture resulted in activation of the PU.1 promoter and an increased number of PU.1+ cells with myeloid gene signature and differentiation potential. In vivo, high systemic levels of M-CSF directly stimulated M-CSF-receptor-dependent activation of endogenous PU.1 protein in single HSCs and induced a PU.1-dependent myeloid differentiation preference. Our data demonstrate that lineage-specific cytokines can act directly on HSCs in vitro and in vivo to instruct a change of cell identity. This fundamentally changes the current view of how HSCs respond to environmental challenge and implicates stress-induced cytokines as direct instructors of HSC fate. PMID:23575636

  12. The WTX Tumor Suppressor Regulates Mesenchymal Progenitor Cell Fate Specification

    PubMed Central

    Lotinun, Sutada; Akhavanfard, Sara; Coffman, Erik J.; Cook, Edward B.; Stoykova, Svetlana; Mukherjee, Siddhartha; Schoonmaker, Jesse A.; Burger, Alexa; Kim, Woo Jae; Kronenberg, Henry M.; Baron, Roland; Haber, Daniel A.; Bardeesy, Nabeel

    2014-01-01

    SUMMARY WTX is an X-linked tumor suppressor targeted by somatic mutations in Wilms tumor, a pediatric kidney cancer, and by germline inactivation in osteopathia striata with cranial sclerosis, a bone overgrowth syndrome. Here, we show that Wtx deletion in mice causes neonatal lethality, somatic overgrowth, and malformation of multiple mesenchyme-derived tissues, including bone, fat, kidney, heart, and spleen. Inactivation of Wtx at different developmental stages and in primary mesenchymal progenitor cells (MPCs) reveals that bone mass increase and adipose tissue deficiency are due to altered lineage fate decisions coupled with delayed terminal differentiation. Specification defects in MPCs result from aberrant β-catenin activation, whereas alternative pathways contribute to the subsequently delayed differentiation of lineage-restricted cells. Thus, Wtx is a regulator of MPC commitment and differentiation with stage-specific functions in inhibiting canonical Wnt signaling. Furthermore, the constellation of anomalies in Wtx null mice suggests that this tumor suppressor broadly regulates MPCs in multiple tissues. PMID:21571217

  13. MSX2 in ameloblast cell fate and activity

    PubMed Central

    Babajko, Sylvie; de La Dure-Molla, Muriel; Jedeon, Katia; Berdal, Ariane

    2015-01-01

    While many effectors have been identified in enamel matrix and cells via genetic studies, physiological networks underlying their expression levels and thus the natural spectrum of enamel thickness and degree of mineralization are now just emerging. Several transcription factors are candidates for enamel gene expression regulation and thus the control of enamel quality. Some of these factors, such as MSX2, are mainly confined to the dental epithelium. MSX2 homeoprotein controls several stages of the ameloblast life cycle. This chapter introduces MSX2 and its target genes in the ameloblast and provides an overview of knowledge regarding its effects in vivo in transgenic mouse models. Currently available in vitro data on the role of MSX2 as a transcription factor and its links to other players in ameloblast gene regulation are considered. MSX2 modulations are relevant to the interplay between developmental, hormonal and environmental pathways and in vivo investigations, notably in the rodent incisor, have provided insight into dental physiology. Indeed, in vivo models are particularly promising for investigating enamel formation and MSX2 function in ameloblast cell fate. MSX2 may be central to the temporal-spatial restriction of enamel protein production by the dental epithelium and thus regulation of enamel quality (thickness and mineralization level) under physiological and pathological conditions. Studies on MSX2 show that amelogenesis is not an isolated process but is part of the more general physiology of coordinated dental-bone complex growth. PMID:25601840

  14. Neurogenin 3 Expressing Cells in the Human Exocrine Pancreas Have the Capacity for Endocrine Cell Fate

    PubMed Central

    Gomez, Danielle L.; O’Driscoll, Marci; Sheets, Timothy P.; Hruban, Ralph H.; Oberholzer, Jose; McGarrigle, James J.; Shamblott, Michael J.

    2015-01-01

    Neurogenin 3 (NGN3) is necessary and sufficient for endocrine differentiation during pancreatic development and is expressed by a population of progenitor cells that give rise exclusively to hormone-secreting cells within islets. NGN3 protein can be detected in the adult rodent pancreas only following certain types of injury, when it is transiently expressed by exocrine cells undergoing reprogramming to an endocrine cell fate. Here, NGN3 protein can be detected in 2% of acinar and duct cells in living biopsies of histologically normal adult human pancreata and 10% in cadaveric biopsies of organ donor pancreata. The percentage and total number of NGN3+ cells increase during culture without evidence of proliferation or selective cell death. Isolation of highly purified and viable NGN3+ cell populations can be achieved based on coexpression of the cell surface glycoprotein CD133. Transcriptome and targeted expression analyses of isolated CD133+ / NGN3+ cells indicate that they are distinct from surrounding exocrine tissue with respect to expression phenotype and Notch signaling activity, but retain high level mRNA expression of genes indicative of acinar and duct cell function. NGN3+ cells have an mRNA expression profile that resembles that of mouse early endocrine progenitor cells. During in vitro differentiation, NGN3+ cells express genes in a pattern characteristic of endocrine development and result in cells that resemble beta cells on the basis of coexpression of insulin C-peptide, chromogranin A and pancreatic and duodenal homeobox 1. NGN3 expression in the adult human exocrine pancreas marks a dedifferentiating cell population with the capacity to take on an endocrine cell fate. These cells represent a potential source for the treatment of diabetes either through ex vivo manipulation, or in vivo by targeting mechanisms controlling their population size and endocrine cell fate commitment. PMID:26288179

  15. The Arabidopsis Receptor Kinase ZAR1 Is Required for Zygote Asymmetric Division and Its Daughter Cell Fate.

    PubMed

    Yu, Tian-Ying; Shi, Dong-Qiao; Jia, Peng-Fei; Tang, Jun; Li, Hong-Ju; Liu, Jie; Yang, Wei-Cai

    2016-03-01

    Asymmetric division of zygote is critical for pattern formation during early embryogenesis in plants and animals. It requires integration of the intrinsic and extrinsic cues prior to and/or after fertilization. How these cues are translated into developmental signals is poorly understood. Here through genetic screen for mutations affecting early embryogenesis, we identified an Arabidopsis mutant, zygotic arrest 1 (zar1), in which zygote asymmetric division and the cell fate of its daughter cells were impaired. ZAR1 encodes a member of the RLK/Pelle kinase family. We demonstrated that ZAR1 physically interacts with Calmodulin and the heterotrimeric G protein Gβ, and ZAR1 kinase is activated by their binding as well. ZAR1 is specifically expressed micropylarly in the embryo sac at eight-nucleate stage and then in central cell, egg cell and synergids in the mature embryo sac. After fertilization, ZAR1 is accumulated in zygote and endosperm. The disruption of ZAR1 and AGB1 results in short basal cell and an apical cell with basal cell fate. These data suggest that ZAR1 functions as a membrane integrator for extrinsic cues, Ca2+ signal and G protein signaling to regulate the division of zygote and the cell fate of its daughter cells in Arabidopsis. PMID:27014878

  16. The Arabidopsis Receptor Kinase ZAR1 Is Required for Zygote Asymmetric Division and Its Daughter Cell Fate

    PubMed Central

    Jia, Peng-Fei; Tang, Jun; Li, Hong-Ju; Liu, Jie; Yang, Wei-Cai

    2016-01-01

    Asymmetric division of zygote is critical for pattern formation during early embryogenesis in plants and animals. It requires integration of the intrinsic and extrinsic cues prior to and/or after fertilization. How these cues are translated into developmental signals is poorly understood. Here through genetic screen for mutations affecting early embryogenesis, we identified an Arabidopsis mutant, zygotic arrest 1 (zar1), in which zygote asymmetric division and the cell fate of its daughter cells were impaired. ZAR1 encodes a member of the RLK/Pelle kinase family. We demonstrated that ZAR1 physically interacts with Calmodulin and the heterotrimeric G protein Gβ, and ZAR1 kinase is activated by their binding as well. ZAR1 is specifically expressed micropylarly in the embryo sac at eight-nucleate stage and then in central cell, egg cell and synergids in the mature embryo sac. After fertilization, ZAR1 is accumulated in zygote and endosperm. The disruption of ZAR1 and AGB1 results in short basal cell and an apical cell with basal cell fate. These data suggest that ZAR1 functions as a membrane integrator for extrinsic cues, Ca2+ signal and G protein signaling to regulate the division of zygote and the cell fate of its daughter cells in Arabidopsis. PMID:27014878

  17. T Cell Fate at the Single-Cell Level.

    PubMed

    Buchholz, Veit R; Schumacher, Ton N M; Busch, Dirk H

    2016-05-20

    T cell responses display two key characteristics. First, a small population of epitope-specific naive T cells expands by several orders of magnitude. Second, the T cells within this proliferating population take on diverse functional and phenotypic properties that determine their ability to exert effector functions and contribute to T cell memory. Recent technological advances in lineage tracing allow us for the first time to study these processes in vivo at single-cell resolution. Here, we summarize resulting data demonstrating that although epitope-specific T cell responses are reproducibly similar at the population level, expansion potential and diversification patterns of the offspring derived from individual T cells are highly variable during both primary and recall immune responses. In spite of this stochastic response variation, individual memory T cells can serve as adult stem cells that provide robust regeneration of an epitope-specific tissue through population averaging. We discuss the relevance of these findings for T cell memory formation and clinical immunotherapy.

  18. O-GlcNAcylation Negatively Regulates Cardiomyogenic Fate in Adult Mouse Cardiac Mesenchymal Stromal Cells

    PubMed Central

    Zafir, Ayesha; Bradley, James A.; Long, Bethany W.; Muthusamy, Senthilkumar; Li, Qianhong; Hill, Bradford G.; Wysoczynski, Marcin; Prabhu, Sumanth D.; Bhatnagar, Aruni; Bolli, Roberto; Jones, Steven P.

    2015-01-01

    In both preclinical and clinical studies, cell transplantation of several cell types is used to promote repair of damaged organs and tissues. Nevertheless, despite the widespread use of such strategies, there remains little understanding of how the efficacy of cell therapy is regulated. We showed previously that augmentation of a unique, metabolically derived stress signal (i.e., O-GlcNAc) improves survival of cardiac mesenchymal stromal cells; however, it is not known whether enhancing O-GlcNAcylation affects lineage commitment or other aspects of cell competency. In this study, we assessed the role of O-GlcNAc in differentiation of cardiac mesenchymal stromal cells. Exposure of these cells to routine differentiation protocols in culture increased markers of the cardiomyogenic lineage such as Nkx2.5 and connexin 40, and augmented the abundance of transcripts associated with endothelial and fibroblast cell fates. Differentiation significantly decreased the abundance of O-GlcNAcylated proteins. To determine if O-GlcNAc is involved in stromal cell differentiation, O-GlcNAcylation was increased pharmacologically during the differentiation protocol. Although elevated O-GlcNAc levels did not significantly affect fibroblast and endothelial marker expression, acquisition of cardiomyocyte markers was limited. In addition, increasing O-GlcNAcylation further elevated smooth muscle actin expression. In addition to lineage commitment, we also evaluated proliferation and migration, and found that increasing O-GlcNAcylation did not significantly affect either; however, we found that O-GlcNAc transferase—the protein responsible for adding O-GlcNAc to proteins—is at least partially required for maintaining cellular proliferative and migratory capacities. We conclude that O-GlcNAcylation contributes significantly to cardiac mesenchymal stromal cell lineage and function. O-GlcNAcylation and pathological conditions that may affect O-GlcNAc levels (such as diabetes) should be

  19. Control of stem cell fate by engineering their micro and nanoenvironment

    PubMed Central

    Griffin, Michelle F; Butler, Peter E; Seifalian, Alexander M; Kalaskar, Deepak M

    2015-01-01

    Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix (ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine. PMID:25621104

  20. G2 phase arrest prevents bristle progenitor self-renewal and synchronizes cell division with cell fate differentiation.

    PubMed

    Ayeni, Joseph O; Audibert, Agnès; Fichelson, Pierre; Srayko, Martin; Gho, Michel; Campbell, Shelagh D

    2016-04-01

    Developmentally regulated cell cycle arrest is a fundamental feature of neurogenesis, whose significance is poorly understood. During Drosophila sensory organ (SO) development, primary progenitor (pI) cells arrest in G2 phase for precisely defined periods. Upon re-entering the cell cycle in response to developmental signals, these G2-arrested precursor cells divide and generate specialized neuronal and non-neuronal cells. To study how G2 phase arrest affects SO lineage specification, we forced pI cells to divide prematurely. This produced SOs with normal neuronal lineages but supernumerary non-neuronal cell types because prematurely dividing pI cells generate a secondary pI cell that produces a complete SO and an external precursor cell that undergoes amplification divisions. pI cells are therefore able to undergo self-renewal before transit to a terminal mode of division. Regulation of G2 phase arrest thus serves a dual role in SO development: preventing progenitor self-renewal and synchronizing cell division with developmental signals. Cell cycle arrest in G2 phase temporally coordinates the precursor cell proliferation potential with terminal cell fate determination to ensure formation of organs with a normal set of sensory cells.

  1. Mesenchymal stem cells instruct oligodendrogenic fate decision on adult neural stem cells.

    PubMed

    Rivera, Francisco J; Couillard-Despres, Sebastien; Pedre, Xiomara; Ploetz, Sonja; Caioni, Massimiliano; Lois, Carlos; Bogdahn, Ulrich; Aigner, Ludwig

    2006-10-01

    Adult stem cells reside in different tissues and organs of the adult organism. Among these cells are MSCs that are located in the adult bone marrow and NSCs that exist in the adult central nervous system (CNS). In transplantation experiments, MSCs demonstrated neuroprotective and neuroregenerative effects that were associated with functional improvements. The underlying mechanisms are largely unidentified. Here, we reveal that the interactions between adult MSCs and NSCs, mediated by soluble factors, induce oligodendrogenic fate decision in NSCs at the expense of astrogenesis. This was demonstrated (a) by an increase in the percentage of cells expressing the oligodendrocyte markers GalC and myelin basic protein, (b) by a reduction in the percentage of glial fibrillary acidic protein (GFAP)-expressing cells, and (c) by the expression pattern of cell fate determinants specific for oligodendrogenic differentiation. Thus, it involved enhanced expression of the oligodendrogenic transcription factors Olig1, Olig2, and Nkx2.2 and diminished expression of Id2, an inhibitor of oligodendrogenic differentiation. Results of (a) 5-bromo-2'-deoxyuridine pulse-labeling of cells, (b) cell fate analysis, and (c) cell death/survival analysis suggested an inductive mechanism and excluded a selection process. A candidate factor screen excluded a number of growth factors, cytokines, and neurotrophins that have previously been shown to influence neurogenesis and neural differentiation from the oligodendrogenic activity derived from the MSCs. This work might have major implications for the development of future transplantation strategies for the treatment of degenerative diseases in the CNS. PMID:16763198

  2. Asymmetric localization and function of cell-fate determinants: a fly's view.

    PubMed

    Bardin, Allison J; Le Borgne, Roland; Schweisguth, François

    2004-02-01

    One mechanism to generate daughter cells with distinct fates is the asymmetric inheritance of regulatory proteins, leading to differential gene regulation in the daughter cells. This mode of cell division is termed 'asymmetric cell division.' The nervous system of the fly employs asymmetric cell division, both in the central nervous system, to generate neural precursors, neurons and glial cells; and in the peripheral nervous system, to create sensory organs that are composed of multiple cell types. These cell lineages are excellent models to examine the gene expression program that leads to fate acquisition, the cell-fate determinants that control these programs and how these determinants, in turn, are distributed through cell polarity machinery.

  3. Regulated cell-to-cell variation in a cell-fate decision system.

    PubMed

    Colman-Lerner, Alejandro; Gordon, Andrew; Serra, Eduard; Chin, Tina; Resnekov, Orna; Endy, Drew; Pesce, C Gustavo; Brent, Roger

    2005-09-29

    Here we studied the quantitative behaviour and cell-to-cell variability of a prototypical eukaryotic cell-fate decision system, the mating pheromone response pathway in yeast. We dissected and measured sources of variation in system output, analysing thousands of individual, genetically identical cells. Only a small proportion of total cell-to-cell variation is caused by random fluctuations in gene transcription and translation during the response ('expression noise'). Instead, variation is dominated by differences in the capacity of individual cells to transmit signals through the pathway ('pathway capacity') and to express proteins from genes ('expression capacity'). Cells with high expression capacity express proteins at a higher rate and increase in volume more rapidly. Our results identify two mechanisms that regulate cell-to-cell variation in pathway capacity. First, the MAP kinase Fus3 suppresses variation at high pheromone levels, while the MAP kinase Kss1 enhances variation at low pheromone levels. Second, pathway capacity and expression capacity are negatively correlated, suggesting a compensatory mechanism that allows cells to respond more precisely to pheromone in the presence of a large variation in expression capacity. PMID:16170311

  4. Potency and fate specification in CNS stem cell populations in vitro.

    PubMed

    Ravin, Rea; Hoeppner, Daniel J; Munno, David M; Carmel, Liran; Sullivan, Jim; Levitt, David L; Miller, Jennifer L; Athaide, Christopher; Panchision, David M; McKay, Ronald D G

    2008-12-01

    To realize the promise of stem cell biology, it is important to identify the precise time in the history of the cell when developmental potential is restricted. To achieve this goal, we developed a real-time imaging system that captures the transitions in fate, generating neurons, astrocytes, and oligodendrocytes from single CNS stem cells in vitro. In the presence of bFGF, tripotent cells normally produce specified progenitors through a bipotent intermediate cell type. Surprisingly, the tripotent state is reset at each passage. The cytokine CNTF is thought to instruct multipotent cells to an astrocytic fate. We demonstrate that CNTF both directs astrogliogenesis from tripotent cells, bypassing two of the three normal bipotent intermediates, and later promotes the expansion of specified astrocytic progenitors. These results show how discrete cell types emerge from a multipotent cell and provide a strong basis for future studies to determine the molecular basis of fate specification.

  5. Mineral-Water Interface Processes Affecting Uranium Fate in Contaminated Sediments

    NASA Astrophysics Data System (ADS)

    Catalano, J. G.

    2011-12-01

    Widespread uranium contamination of soil, sediments, and groundwater systems has resulted from mining activities, nuclear weapon production, and energy generation. The fate and transport of uranium in such systems is strongly affected by geochemical processes occurring at mineral-water interfaces. I will present a summary of the mineral-water interface processes found to affect uranium fate in example contaminated sediments at the U.S. Department of Energy's Hanford sites and in related model systems. Processes occurring under oxic conditions will be the primary focus of this talk as under these conditions uranium is most mobile and thus presents the greatest hazard. Three dominant solid-phase uranium species are observed in contaminated soil and sediments at the Hanford site: uranyl silicates, uranyl phosphates, and uranyl adsorbed to clays and iron oxides. In deep sediments, uranyl silicates are found in microfractures in feldspar grains, likely because slow diffusion in such fractures maintains a high silicate activity. Such silicates are also found in waste-impacted shallow sediments and soil; waste fluids or evaporative processes may have generated the silicate activity needed to produce such phases. Uranyl phosphates are less abundant, occurring primarily in shallow sediments exposed to P-bearing waste fluids. However, remediation approaches under consideration may produce substantial quantities of uranyl phosphates in the future. Adsorbed uranyl is dispersed throughout contaminated soils and shallow sediments and likely has the greatest potential for remobilization. Analogue studies show that precipitation of uranyl phosphates is rapid when such phases are supersaturated and that both homogeneous and heterogeneous nucleation may occur. Specific adsorption of uranyl to minerals is strongly affected by the presence of complexation anions. Carbonate suppresses uranyl adsorption but also forms uranyl-carbonate ternary surface complexes. At conditions below

  6. Autophagy variation within a cell population determines cell fate through selective degradation of Fap-1.

    PubMed

    Gump, Jacob M; Staskiewicz, Leah; Morgan, Michael J; Bamberg, Alison; Riches, David W H; Thorburn, Andrew

    2014-01-01

    Autophagy regulates cell death both positively and negatively, but the molecular basis for this paradox remains inadequately characterized. We demonstrate here that transient cell-to-cell variations in autophagy can promote either cell death or survival depending on the stimulus and cell type. By separating cells with high and low basal autophagy using flow cytometry, we demonstrate that autophagy determines which cells live or die in response to death receptor activation. We have determined that selective autophagic degradation of the phosphatase Fap-1 promotes Fas apoptosis in Type I cells, which do not require mitochondrial permeabilization for efficient apoptosis. Conversely, autophagy inhibits apoptosis in Type II cells (which require mitochondrial involvement) or on treatment with TRAIL in either Type I or II cells. These data illustrate that differences in autophagy in a cell population determine cell fate in a stimulus- and cell-type-specific manner. This example of selective autophagy of an apoptosis regulator may represent a general mechanism for context-specific regulation of cell fate by autophagy. PMID:24316673

  7. Bone marrow-derived Schwann cells achieve fate commitment--a prerequisite for remyelination therapy.

    PubMed

    Shea, Graham K H; Tsui, Alex Y P; Chan, Ying Shing; Shum, Daisy K Y

    2010-08-01

    Schwann cell transplantation improves post-traumatic nerve regeneration in both PNS and CNS but sufficient numbers of immunocompatible cells are required for clinical application. Currently, Schwann cell-like cells derived from the bone marrow lack fate commitment and revert to a fibroblast-like phenotype upon withdrawal of differentiation-inducing factors. In recapitulation of embryonic events leading to Schwann cell maturation, we hypothesize that the Schwann cell-like cells acquire the switch to fate commitment through contact-dependent cues from incipient neurons of the developing dorsal root ganglia. To address this, Schwann cell-like cells derived from adult rat bone marrow were cocultured with neurons purified from embryonic dorsal root ganglia. A cell-intrinsic switch to the Schwann cell fate was achieved consistently and the cell progeny maintained expression of the markers S100 beta, p75(NTR) , GFAP, P0 and Sox 10 even without exogenous differentiation-inducing factors or neurons. In vitro formation of MBP-positive segments under myelinating conditions by the cell progeny was comparable to that by sciatic nerve-derived Schwann cells. Controls in which Schwann cell-like cells were barred from direct contact with neurons in coculture reverted to SMA/CD90-expressing myofibroblasts. We demonstrate therefore for the first time fate commitment among bone marrow-derived Schwann cells. The therapeutic potential of these cells may be tested in future transplantation studies. (206 words).

  8. Abeta40 promotes neuronal cell fate in neural progenitor cells.

    PubMed

    Chen, Y; Dong, C

    2009-03-01

    Sequential cleavage of the amyloid precursor protein (APP) by beta- and then gamma- secretase gives rise to Abeta(1-40) (Abeta40), a major species of Abeta (beta-amyloid) produced by neurons under physiological conditions. Abeta(1-42) (Abeta42), a minor species of Abeta, is also produced by a similar but less understood mechanism of the gamma-secretase. The physiological functions of these Abeta species remain to be defined. In this report, we demonstrate that freshly prepared soluble Abeta40 significantly promotes neurogenesis in primary neural progenitor cells (NPCs). First, Abeta40 increases neuronal markers as determined by NeuN expression and Tuj1 promoter activity, differing from Abeta42, which induces astrocyte markers in NPCs. Second, Abeta40 induces neuronal differentiation at the end of S-phase in the cell cycle. Third, Abeta40 promotes NPC entry into S-phase, playing a role in NPC self-renewal. Interestingly, Abeta40 does not significantly increase apoptotic indexes such as DNA condensation and DNA fragmentation. In addition, Abeta40 does not augment caspase-3 activation in NeuN(+) or nestin(+) cells. Collectively, this report provides strong evidence that Abeta40 is a neurogenic factor and suggests that the debilitated function of Abeta40 in neurogenesis may account for the shortage of neurons in Alzheimer's disease.

  9. Blastomeres show differential fate changes in 8-cell Xenopus laevis embryos that are rotated 90 degrees before first cleavage

    NASA Technical Reports Server (NTRS)

    Huang, S.; Johnson, K. E.; Wang, H. Z.

    1998-01-01

    To study the mechanisms of dorsal axis specification, the alteration in dorsal cell fate of cleavage stage blastomeres in axis-respecified Xenopus laevis embryos was investigated. Fertilized eggs were rotated 90 degrees with the sperm entry point up or down with respect to the gravitational field. At the 8-cell stage, blastomeres were injected with the lineage tracers, Texas Red- or FITC-Dextran Amines. The distribution of the labeled progeny was mapped at the tail-bud stages (stages 35-38) and compared with the fate map of an 8-cell embryo raised in a normal orientation. As in the normal embryos, each blastomere in the rotated embryos has a characteristic and predictable cell fate. After 90 degrees rotation the blastomeres in the 8-cell stage embryo roughly switched their position by 90 degrees, but the fate of the blastomeres did not simply show a 90 degrees switch appropriate for their new location. Four types of fate change were observed: (i) the normal fate of the blastomere is conserved with little change; (ii) the normal fate is completely changed and a new fate is adopted according to the blastomere's new position: (iii) the normal fate is completely changed, but the new fate is not appropriate for its new position; and (4) the blastomere partially changed its fate and the new fate is a combination of its original fate and a fate appropriate to its new location. According to the changed fates, the blastomeres that adopt dorsal fates were identified in rotated embryos. This identification of dorsal blastomeres provides basic important information for further study of dorsal signaling in Xenopus embryos.

  10. Role of stress-activated OCT4A in the cell fate decisions of embryonal carcinoma cells treated with etoposide.

    PubMed

    Huna, Anda; Salmina, Kristine; Erenpreisa, Jekaterina; Vazquez-Martin, Alejandro; Krigerts, Jekabs; Inashkina, Inna; Gerashchenko, Bogdan I; Townsend, Paul A; Cragg, Mark S; Jackson, Thomas R

    2015-01-01

    Tumor cellular senescence induced by genotoxic treatments has recently been found to be paradoxically linked to the induction of "stemness." This observation is critical as it directly impinges upon the response of tumors to current chemo-radio-therapy treatment regimens. Previously, we showed that following etoposide (ETO) treatment embryonal carcinoma PA-1 cells undergo a p53-dependent upregulation of OCT4A and p21Cip1 (governing self-renewal and regulating cell cycle inhibition and senescence, respectively). Here we report further detail on the relationship between these and other critical cell-fate regulators. PA-1 cells treated with ETO display highly heterogeneous increases in OCT4A and p21Cip1 indicative of dis-adaptation catastrophe. Silencing OCT4A suppresses p21Cip1, changes cell cycle regulation and subsequently suppresses terminal senescence; p21Cip1-silencing did not affect OCT4A expression or cellular phenotype. SOX2 and NANOG expression did not change following ETO treatment suggesting a dissociation of OCT4A from its pluripotency function. Instead, ETO-induced OCT4A was concomitant with activation of AMPK, a key component of metabolic stress and autophagy regulation. p16ink4a, the inducer of terminal senescence, underwent autophagic sequestration in the cytoplasm of ETO-treated cells, allowing alternative cell fates. Accordingly, failure of autophagy was accompanied by an accumulation of p16ink4a, nuclear disintegration, and loss of cell recovery. Together, these findings imply that OCT4A induction following DNA damage in PA-1 cells, performs a cell stress, rather than self-renewal, function by moderating the expression of p21Cip1, which alongside AMPK helps to then regulate autophagy. Moreover, this data indicates that exhaustion of autophagy, through persistent DNA damage, is the cause of terminal cellular senescence. PMID:26102294

  11. Trace contaminant concentration affects mineral transformation and pollutant fate in hydroxide-weathered Hanford sediments.

    PubMed

    Perdrial, Nicolas; Rivera, Nelson; Thompson, Aaron; O'Day, Peggy A; Chorover, Jon

    2011-12-15

    Prior work has shown that when silicaceous sediments are infused with caustic radioactive waste, contaminant fate is tightly coupled to ensuing mineral weathering reactions. However, the effects of local aqueous geochemical conditions on these reactions are poorly studied. Thus, we varied contaminant concentration and pCO(2) during the weathering of previously uncontaminated Hanford sediments over 6 months and 1 year in a solution of caustic waste (pH 13, high ionic strength). Co-contaminants Sr, Cs and I were added at "low" (Cs/Sr: 10(-5)m; I: 10(-7)m) and "high" (Cs/Sr: 10(-3)m; I: 10(-5)m) concentrations, and headspace was held at atmospheric or undetectable (<10ppmv) CO(2) partial pressure. Solid phase characterization revealed the formation of the zeolite chabazite in "high" samples, whereas feldspathoids, sodalite and cancrinite, were formed preferentially in "low" samples. Sr, Cs and I were sequestered in all reacted sediments. Native calcite dissolution in the CO(2)-free treatment drove the formation of strätlingite (Ca(2)Al(2)SiO(7)·8H(2)O) and diminished availability of Si and Al for feldspathoid formation. Results indicate that pCO(2) and contaminant concentrations strongly affect contaminant speciation in waste-weathered sediments, and are therefore likely to impact reaction product stability under any remediation scenario.

  12. Memory of cell shape biases stochastic fate decision-making despite mitotic rounding.

    PubMed

    Akanuma, Takashi; Chen, Cong; Sato, Tetsuo; Merks, Roeland M H; Sato, Thomas N

    2016-01-01

    Cell shape influences function, and the current model suggests that such shape effect is transient. However, cells dynamically change their shapes, thus, the critical question is whether shape information remains influential on future cell function even after the original shape is lost. We address this question by integrating experimental and computational approaches. Quantitative live imaging of asymmetric cell-fate decision-making and their live shape manipulation demonstrates that cellular eccentricity of progenitor cell indeed biases stochastic fate decisions of daughter cells despite mitotic rounding. Modelling and simulation indicates that polarized localization of Delta protein instructs by the progenitor eccentricity is an origin of the bias. Simulation with varying parameters predicts that diffusion rate and abundance of Delta molecules quantitatively influence the bias. These predictions are experimentally validated by physical and genetic methods, showing that cells exploit a mechanism reported herein to influence their future fates based on their past shape despite dynamic shape changes. PMID:27349214

  13. Memory of cell shape biases stochastic fate decision-making despite mitotic rounding

    PubMed Central

    Akanuma, Takashi; Chen, Cong; Sato, Tetsuo; Merks, Roeland M. H.; Sato, Thomas N.

    2016-01-01

    Cell shape influences function, and the current model suggests that such shape effect is transient. However, cells dynamically change their shapes, thus, the critical question is whether shape information remains influential on future cell function even after the original shape is lost. We address this question by integrating experimental and computational approaches. Quantitative live imaging of asymmetric cell-fate decision-making and their live shape manipulation demonstrates that cellular eccentricity of progenitor cell indeed biases stochastic fate decisions of daughter cells despite mitotic rounding. Modelling and simulation indicates that polarized localization of Delta protein instructs by the progenitor eccentricity is an origin of the bias. Simulation with varying parameters predicts that diffusion rate and abundance of Delta molecules quantitatively influence the bias. These predictions are experimentally validated by physical and genetic methods, showing that cells exploit a mechanism reported herein to influence their future fates based on their past shape despite dynamic shape changes. PMID:27349214

  14. Memory of cell shape biases stochastic fate decision-making despite mitotic rounding.

    PubMed

    Akanuma, Takashi; Chen, Cong; Sato, Tetsuo; Merks, Roeland M H; Sato, Thomas N

    2016-01-01

    Cell shape influences function, and the current model suggests that such shape effect is transient. However, cells dynamically change their shapes, thus, the critical question is whether shape information remains influential on future cell function even after the original shape is lost. We address this question by integrating experimental and computational approaches. Quantitative live imaging of asymmetric cell-fate decision-making and their live shape manipulation demonstrates that cellular eccentricity of progenitor cell indeed biases stochastic fate decisions of daughter cells despite mitotic rounding. Modelling and simulation indicates that polarized localization of Delta protein instructs by the progenitor eccentricity is an origin of the bias. Simulation with varying parameters predicts that diffusion rate and abundance of Delta molecules quantitatively influence the bias. These predictions are experimentally validated by physical and genetic methods, showing that cells exploit a mechanism reported herein to influence their future fates based on their past shape despite dynamic shape changes.

  15. Choose your destiny: Make a cell fate decision with COUP-TFII.

    PubMed

    Wu, San-Pin; Yu, Cheng-Tai; Tsai, Sophia Y; Tsai, Ming-Jer

    2016-03-01

    Cell fate specification is a critical process to generate cells with a wide range of characteristics from stem and progenitor cells. Emerging evidence demonstrates that the orphan nuclear receptor COUP-TFII serves as a key regulator in determining the cell identity during embryonic development. The present review summarizes our current knowledge on molecular mechanisms by which COUP-TFII employs to define the cell fates, with special emphasis on cardiovascular and renal systems. These novel insights pave the road for future studies of regenerative medicine.

  16. Cell Fate and Differentiation of Bone Marrow Mesenchymal Stem Cells

    PubMed Central

    Jimi, Eijiro

    2016-01-01

    Osteoblasts and bone marrow adipocytes originate from bone marrow mesenchymal stem cells (BMMSCs) and there appears to be a reciprocal relationship between adipogenesis and osteoblastogenesis. Alterations in the balance between adipogenesis and osteoblastogenesis in BMMSCs wherein adipogenesis is increased relative to osteoblastogenesis are associated with decreased bone quality and quantity. Several proteins have been reported to regulate this reciprocal relationship but the exact nature of the signals regulating the balance between osteoblast and adipocyte formation within the bone marrow space remains to be determined. In this review, we focus on the role of Transducin-Like Enhancer of Split 3 (TLE3), which was recently reported to regulate the balance between osteoblast and adipocyte formation from BMMSCs. We also discuss evidence implicating canonical Wnt signalling, which plays important roles in both adipogenesis and osteoblastogenesis, in regulating TLE3 expression. Currently, there is demand for new effective therapies that target the stimulation of osteoblast differentiation to enhance bone formation. We speculate that reducing TLE3 expression or activity in BMMSCs could be a useful approach towards increasing osteoblast numbers and reducing adipogenesis in the bone marrow environment. PMID:27298623

  17. Harnessing nanotopography and integrin-matrix interactions to influence stem cell fate

    NASA Astrophysics Data System (ADS)

    Dalby, Matthew J.; Gadegaard, Nikolaj; Oreffo, Richard O. C.

    2014-06-01

    Stem cells respond to nanoscale surface features, with changes in cell growth and differentiation mediated by alterations in cell adhesion. The interaction of nanotopographical features with integrin receptors in the cells' focal adhesions alters how the cells adhere to materials surfaces, and defines cell fate through changes in both cell biochemistry and cell morphology. In this Review, we discuss how cell adhesions interact with nanotopography, and we provide insight as to how materials scientists can exploit these interactions to direct stem cell fate and to understand how the behaviour of stem cells in their niche can be controlled. We expect knowledge gained from the study of cell-nanotopography interactions to accelerate the development of next-generation stem cell culture materials and implant interfaces, and to fuel discovery of stem cell therapeutics to support regenerative therapies.

  18. Positional cues specify and maintain aleurone cell fate in maize endosperm development.

    PubMed

    Becraft, P W; Asuncion-Crabb, Y

    2000-09-01

    A genetic analysis of maize aleurone development was conducted. Cell lineage was examined by simultaneously marking cells with C1 for anthocyanin pigmentation in the aleurone and wx1 for amylose synthesis in the starchy endosperm. The aleurone and starchy endosperm share a common lineage throughout development indicating that positional cues specify aleurone fate. Mutants in dek1 block aleurone formation at an early stage and cause peripheral endosperm cells to develop as starchy endosperm. Revertant sectors of a transposon-induced dek1 allele showed that peripheral endosperm cells remain competent to differentiate as aleurone cells until late in development. Ds-induced chromosome breakage was used to generate Dek1 loss-of-function sectors. Events occurring until late development caused aleurone cells to switch fate to starchy endosperm indicating that cell fate is not fixed. Thus, positional cues are required to specify and maintain aleurone fate and Dek1 function is required to respond to these cues. An analysis of additional mutants that disrupt aleurone differentiation suggests a hierarchy of gene functions to specify aleurone cell fate and then control aleurone differentiation. These mutants disrupt aleurone differentiation in reproducible patterns suggesting a relationship to endosperm pattern formation.

  19. Role of Geminin in cell fate determination of hematopoietic stem cells (HSCs).

    PubMed

    Yasunaga, Shin'ichiro; Ohno, Yoshinori; Shirasu, Naoto; Zhang, Bo; Suzuki-Takedachi, Kyoko; Ohtsubo, Motoaki; Takihara, Yoshihiro

    2016-09-01

    Geminin exerts two distinct molecular roles. Geminin negatively regulates DNA replication licensing through the direct interaction with Cdt1 to prevent re-replication in proliferating cells. Geminin also regulates chromatin remodeling through the direct interaction with Brahma/Brg1 to maintain undifferentiated states of stem cells. We previously uncovered that Polycomb-group complex 1 and Hoxb4/Hoxa9, well-known intrinsic factors that are essential for maintaining the hematopoietic stem cell (HSC) activity, alternatively act as ubiquitin-proteasome systems for Geminin protein to reduce the protein expression level, and sustain the HSC activity. Thus, Geminin is presumed to play an important role in determining cell fate, i.e., turning on and off cellular quiescence and proliferation/differentiation, in HSCs. We recently generated recombinant cell-penetrating Geminin (CP-Geminin), enabling rapid incorporation and withdraw of Geminin protein in cells. CP-Geminin may be useful in regulating the cell cycle and chromatin configuration. In this article, we summarize current information on the molecular functions of Geminin and the regulatory system for Geminin protein expression, and argue for the molecular role of Geminin in cell fate determination of HSCs, and future perspective of a new technology for manipulating the activities of HSCs and cancer stem cells (CSCs). PMID:27422432

  20. Mesenchymal Stem Cell Fate: Applying Biomaterials for Control of Stem Cell Behavior

    PubMed Central

    Anderson, Hilary J.; Sahoo, Jugal Kishore; Ulijn, Rein V.; Dalby, Matthew J.

    2016-01-01

    The materials pipeline for biomaterials and tissue engineering applications is under continuous development. Specifically, there is great interest in the use of designed materials in the stem cell arena as materials can be used to manipulate the cells providing control of behavior. This is important as the ability to “engineer” complexity and subsequent in vitro growth of tissues and organs is a key objective for tissue engineers. This review will describe the nature of the materials strategies, both static and dynamic, and their influence specifically on mesenchymal stem cell fate. PMID:27242999

  1. Epigenetic setting and reprogramming for neural cell fate determination and differentiation.

    PubMed

    Imamura, Takuya; Uesaka, Masahiro; Nakashima, Kinichi

    2014-09-26

    In the mammalian brain, epigenetic mechanisms are clearly involved in the regulation of self-renewal of neural stem cells and the derivation of their descendants, i.e. neurons, astrocytes and oligodendrocytes, according to the developmental timing and the microenvironment, the 'niche'. Interestingly, local epigenetic changes occur, concomitantly with genome-wide level changes, at a set of gene promoter regions for either down- or upregulation of the gene. In addition, intergenic regions also sensitize the availability of epigenetic modifiers, which affects gene expression through a relatively long-range chromatinic interaction with the transcription regulatory machineries including non-coding RNA (ncRNA) such as promoter-associated ncRNA and enhancer ncRNA. We show that such an epigenetic landscape in a neural cell is statically but flexibly formed together with a variable combination of generally and locally acting nuclear molecules including master transcription factors and cell-cycle regulators. We also discuss the possibility that revealing the epigenetic regulation by the local DNA-RNA-protein assemblies would promote methodological innovations, e.g. neural cell reprogramming, engineering and transplantation, to manipulate neuronal and glial cell fates for the purpose of medical use of these cells.

  2. Various fates of neuronal progenitor cells observed on several different chemical functional groups

    NASA Astrophysics Data System (ADS)

    Liu, Xi; Wang, Ying; He, Jin; Wang, Xiu-Mei; Cui, Fu-Zhai; Xu, Quan-Yuan

    2011-12-01

    Neuronal progenitor cells cultured on gold-coated glass surfaces modified by different chemical functional groups, including hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), bromo (-Br), mercapto (-SH), - Phenyl and methyl (-CH3), were studied here to investigate the influence of surface chemistry on the cells' adhesion, morphology, proliferation and functional gene expression. Focal adhesion staining indicated in the initial culture stage cells exhibited morphological changes in response to different chemical functional groups. Cells cultured on -NH2 grafted surface displayed focal adhesion plaque and flattened morphology and had the largest contact area. However, their counter parts on -CH3 grafted surface displayed no focal adhesion and rounded morphology and had the smallest contact area. After 6 days culture, the proliferation trend was as follows: -NH2 > -SH> -COOH> - Phenyl > - Br > -OH> -CH3. To determine the neural functional properties of the cells affected by surface chemistry, the expression of glutamate decarboxylase (GAD67), nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) were characterized. An increase of GAD67 expression was observed on -NH2, -COOH and -SH grafted surfaces, while no increase in NGF and BDNF expression was observed on any chemical surfaces. These results highlight the importance of surface chemistry in the fate determination of neuronal progenitor cells, and suggest that surface chemistry must be considered in the design of biomaterials for neural tissue engineering.

  3. The planar cell-polarity gene stbm regulates cell behaviour and cell fate in vertebrate embryos.

    PubMed

    Park, Maiyon; Moon, Randall T

    2002-01-01

    The gene strabismus (stbm)/Van Gogh (Vang) functions in the planar cell-polarity pathway in Drosophila. As the existence of such a pathway in vertebrates has not been firmly established, we investigated the functions and signalling activities encoded by stbm in vertebrate embryos. In regard to cell fate, inhibition of Stbm function in zebrafish embryos leads to reduction of anterior neural markers, whereas gain of function leads to a rise in the levels of these markers. In regard to cell behaviour, both gain-of-function and loss-of-function assays reveal a role for Stbm in mediating cell movements during gastrulation. Mechanistically, Stbm inhibits Wnt-mediated activation of beta-catenin-dependent transcription while promoting phosphorylation of c-Jun- and AP-1-dependent transcription. This complex effect on intracellular signalling pathways probably involves dishevelled (dsh), as Stbm was found to interact with the Dsh protein, and as Dsh is known to function in both planar cell-polarity and beta-catenin pathways in Drosophila.

  4. Stealth filaments: Polymer chain length and conformation affect the in vivo fate of PEGylated potato virus X.

    PubMed

    Lee, Karin L; Shukla, Sourabh; Wu, Mengzhi; Ayat, Nadia R; El Sanadi, Caroline E; Wen, Amy M; Edelbrock, John F; Pokorski, Jonathan K; Commandeur, Ulrich; Dubyak, George R; Steinmetz, Nicole F

    2015-06-01

    Nanoparticles hold great promise for delivering medical cargos to cancerous tissues to enhance contrast and sensitivity of imaging agents or to increase specificity and efficacy of therapeutics. A growing body of data suggests that nanoparticle shape, in combination with surface chemistry, affects their in vivo fates, with elongated filaments showing enhanced tumor targeting and tissue penetration, while promoting immune evasion. The synthesis of high aspect ratio filamentous materials at the nanoscale remains challenging using synthetic routes; therefore we turned toward nature's materials, developing and studying the filamentous structures formed by the plant virus potato virus X (PVX). We recently demonstrated that PVX shows enhanced tumor homing in various preclinical models. Like other nanoparticle systems, the proteinaceous platform is cleared from circulation and tissues by the mononuclear phagocyte system (MPS). To increase bioavailability we set out to develop PEGylated stealth filaments and evaluate the effects of PEG chain length and conformation on pharmacokinetics, biodistribution, as well as potential immune and inflammatory responses. We demonstrate that PEGylation effectively reduces immune recognition while increasing pharmacokinetic profiles. Stealth filaments show reduced interaction with cells of the MPS; the protein:polymer hybrids are cleared from the body tissues within hours to days indicating biodegradability and biocompatibility. Tissue compatibility is indicated with no apparent inflammatory signaling in vivo. Tailoring PEG chain length and conformation (brush vs. mushroom) allows tuning of the pharmacokinetics, yielding long-circulating stealth filaments for applications in nanomedicine.

  5. Dependence of stem cell fate in Arabidopsis on a feedback loop regulated by CLV3 activity.

    PubMed

    Brand, U; Fletcher, J C; Hobe, M; Meyerowitz, E M; Simon, R

    2000-07-28

    The fate of stem cells in plant meristems is governed by directional signaling systems that are regulated by negative feedback. In Arabidopsis thaliana, the CLAVATA (CLV) genes encode the essential components of a negative, stem cell-restricting pathway. We used transgenic plants overexpressing CLV3 to show that meristem cell accumulation and fate depends directly on the level of CLV3 activity and that CLV3 signaling occurs exclusively through a CLV1/CLV2 receptor kinase complex. We also demonstrate that the CLV pathway acts by repressing the activity of the transcription factor WUSCHEL, an element of the positive, stem cell-promoting pathway. PMID:10915624

  6. Regulation of monocyte cell fate by blood vessels mediated by Notch signalling.

    PubMed

    Gamrekelashvili, Jaba; Giagnorio, Roberto; Jussofie, Jasmin; Soehnlein, Oliver; Duchene, Johan; Briseño, Carlos G; Ramasamy, Saravana K; Krishnasamy, Kashyap; Limbourg, Anne; Kapanadze, Tamar; Ishifune, Chieko; Hinkel, Rabea; Radtke, Freddy; Strobl, Lothar J; Zimber-Strobl, Ursula; Napp, L Christian; Bauersachs, Johann; Haller, Hermann; Yasutomo, Koji; Kupatt, Christian; Murphy, Kenneth M; Adams, Ralf H; Weber, Christian; Limbourg, Florian P

    2016-08-31

    A population of monocytes, known as Ly6C(lo) monocytes, patrol blood vessels by crawling along the vascular endothelium. Here we show that endothelial cells control their origin through Notch signalling. Using combinations of conditional genetic deletion strategies and cell-fate tracking experiments we show that Notch2 regulates conversion of Ly6C(hi) monocytes into Ly6C(lo) monocytes in vivo and in vitro, thereby regulating monocyte cell fate under steady-state conditions. This process is controlled by Notch ligand delta-like 1 (Dll1) expressed by a population of endothelial cells that constitute distinct vascular niches in the bone marrow and spleen in vivo, while culture on recombinant DLL1 induces monocyte conversion in vitro. Thus, blood vessels regulate monocyte conversion, a form of committed myeloid cell fate regulation.

  7. Regulation of monocyte cell fate by blood vessels mediated by Notch signalling

    PubMed Central

    Gamrekelashvili, Jaba; Giagnorio, Roberto; Jussofie, Jasmin; Soehnlein, Oliver; Duchene, Johan; Briseño, Carlos G.; Ramasamy, Saravana K.; Krishnasamy, Kashyap; Limbourg, Anne; Kapanadze, Tamar; Ishifune, Chieko; Hinkel, Rabea; Radtke, Freddy; Strobl, Lothar J.; Zimber-Strobl, Ursula; Napp, L. Christian; Bauersachs, Johann; Haller, Hermann; Yasutomo, Koji; Kupatt, Christian; Murphy, Kenneth M.; Adams, Ralf H.; Weber, Christian; Limbourg, Florian P.

    2016-01-01

    A population of monocytes, known as Ly6Clo monocytes, patrol blood vessels by crawling along the vascular endothelium. Here we show that endothelial cells control their origin through Notch signalling. Using combinations of conditional genetic deletion strategies and cell-fate tracking experiments we show that Notch2 regulates conversion of Ly6Chi monocytes into Ly6Clo monocytes in vivo and in vitro, thereby regulating monocyte cell fate under steady-state conditions. This process is controlled by Notch ligand delta-like 1 (Dll1) expressed by a population of endothelial cells that constitute distinct vascular niches in the bone marrow and spleen in vivo, while culture on recombinant DLL1 induces monocyte conversion in vitro. Thus, blood vessels regulate monocyte conversion, a form of committed myeloid cell fate regulation. PMID:27576369

  8. Regulation of monocyte cell fate by blood vessels mediated by Notch signalling.

    PubMed

    Gamrekelashvili, Jaba; Giagnorio, Roberto; Jussofie, Jasmin; Soehnlein, Oliver; Duchene, Johan; Briseño, Carlos G; Ramasamy, Saravana K; Krishnasamy, Kashyap; Limbourg, Anne; Kapanadze, Tamar; Ishifune, Chieko; Hinkel, Rabea; Radtke, Freddy; Strobl, Lothar J; Zimber-Strobl, Ursula; Napp, L Christian; Bauersachs, Johann; Haller, Hermann; Yasutomo, Koji; Kupatt, Christian; Murphy, Kenneth M; Adams, Ralf H; Weber, Christian; Limbourg, Florian P

    2016-01-01

    A population of monocytes, known as Ly6C(lo) monocytes, patrol blood vessels by crawling along the vascular endothelium. Here we show that endothelial cells control their origin through Notch signalling. Using combinations of conditional genetic deletion strategies and cell-fate tracking experiments we show that Notch2 regulates conversion of Ly6C(hi) monocytes into Ly6C(lo) monocytes in vivo and in vitro, thereby regulating monocyte cell fate under steady-state conditions. This process is controlled by Notch ligand delta-like 1 (Dll1) expressed by a population of endothelial cells that constitute distinct vascular niches in the bone marrow and spleen in vivo, while culture on recombinant DLL1 induces monocyte conversion in vitro. Thus, blood vessels regulate monocyte conversion, a form of committed myeloid cell fate regulation. PMID:27576369

  9. Manure Injection Affects the Fate of Pirlimycin in Surface Runoff and Soil.

    PubMed

    Kulesza, Stephanie B; Maguire, Rory O; Xia, Kang; Cushman, Julia; Knowlton, Katharine; Ray, Partha

    2016-03-01

    Antibiotics used in animal agriculture are of increasing environmental concern due to the potential for increased antibiotic resistance after land application of manure. Manure application technology may affect the environmental behavior of these antibiotics. Therefore, rainfall simulations were conducted on plots receiving three manure treatments (surface application, subsurface injection, and no manure control) to determine the fate and transport of pirlimycin, an antibiotic commonly used in dairy production. Rainfall simulations were conducted immediately and 7 d after application of dairy manure spiked with 128 ng g (wet weight) pirlimycin. Soil samples were collected from all plots at two depths (0-5 and 5-20 cm). For injection plots, soil was collected from injection slits and between slits. Pirlimycin concentrations were higher in soil within the injection slits compared with surface application plots at 0 and 7 d. Pirlimycin concentrations in the 0- to 5-cm depth decreased by 30, 55, and 87% in the injection slit, between injection slits, and surface application plots 7 d after application. Pirlimycin concentrations were 106 ng g in sediment and 4.67 ng mL in water from the surface application plots, which were 21 and 32 times that of the injection plots, respectively. After 7 d, pirlimycin levels in runoff sediment and water decreased 80 to 98%. Surface application resulted in six and three times higher pirlimycin concentrations in water and sediment than injection. These results indicate that pirlimycin is most susceptible to loss immediately after manure application. Thus, injection could be considered a best management practice to prevent loss of antibiotics in surface runoff. PMID:27065398

  10. Fate of arsenic, phosphate and ammonium plumes in a coastal aquifer affected by saltwater intrusion.

    PubMed

    Colombani, N; Mastrocicco, M; Prommer, H; Sbarbati, C; Petitta, M

    2015-08-01

    A severe groundwater contamination with extensive plumes of arsenic, phosphate and ammonium was found in a coastal aquifer beneath a former fertilizer production plant. The implementation of an active groundwater remediation strategy, based on a comprehensive pump and treat scheme, now prevents the migration of the dissolved contaminants into the marine environment. However, due to the site's proximity to the coastline, a seawater wedge was induced by the pumping scheme. Additionally the groundwater flow and salinity patterns were also strongly affected by leakage from the site's sewer system and from a seawater-fed cooling canal. The objective of this study was to elucidate the fate of arsenic and its co-contaminants over the site's history under the complex, coupled hydrodynamic and geochemical conditions that prevail at the site. A detailed geochemical characterisation of samples from sediment cores and hydrochemical data provided valuable high-resolution information. The obtained data were used to develop various conceptual models and to constrain the development and calibration of a reactive transport model. The reactive transport simulations were performed for a sub-domain (two-dimensional transect) of an earlier developed three-dimensional flow and variable density solute transport model. The results suggest that in the upper sub-oxic zone the influx of oxygenated water promoted As attenuation via co-precipitation with Al and Fe oxides and copper hydroxides. In contrast, in the deeper aquifer zone, iron reduction, associated with the release of adsorbed As and the dissolution of As bearing phases, provided and still provides to date a persistent source for groundwater pollution. The presented monitoring and modelling approach could be broadly applied to coastal polluted sites by complex contaminant mixture containing As. PMID:26093106

  11. Fate of arsenic, phosphate and ammonium plumes in a coastal aquifer affected by saltwater intrusion.

    PubMed

    Colombani, N; Mastrocicco, M; Prommer, H; Sbarbati, C; Petitta, M

    2015-08-01

    A severe groundwater contamination with extensive plumes of arsenic, phosphate and ammonium was found in a coastal aquifer beneath a former fertilizer production plant. The implementation of an active groundwater remediation strategy, based on a comprehensive pump and treat scheme, now prevents the migration of the dissolved contaminants into the marine environment. However, due to the site's proximity to the coastline, a seawater wedge was induced by the pumping scheme. Additionally the groundwater flow and salinity patterns were also strongly affected by leakage from the site's sewer system and from a seawater-fed cooling canal. The objective of this study was to elucidate the fate of arsenic and its co-contaminants over the site's history under the complex, coupled hydrodynamic and geochemical conditions that prevail at the site. A detailed geochemical characterisation of samples from sediment cores and hydrochemical data provided valuable high-resolution information. The obtained data were used to develop various conceptual models and to constrain the development and calibration of a reactive transport model. The reactive transport simulations were performed for a sub-domain (two-dimensional transect) of an earlier developed three-dimensional flow and variable density solute transport model. The results suggest that in the upper sub-oxic zone the influx of oxygenated water promoted As attenuation via co-precipitation with Al and Fe oxides and copper hydroxides. In contrast, in the deeper aquifer zone, iron reduction, associated with the release of adsorbed As and the dissolution of As bearing phases, provided and still provides to date a persistent source for groundwater pollution. The presented monitoring and modelling approach could be broadly applied to coastal polluted sites by complex contaminant mixture containing As.

  12. To Be or Not to Be?: How Selective Autophagy and Cell Death Govern Cell Fate

    PubMed Central

    Green, Douglas R.; Levine, Beth

    2014-01-01

    The health of metazoan organisms requires an effective response to organellar and cellular damage – either by repair of such damage and/or by elimination of the damaged parts of the cells or the damaged cell in its entirety. Here we consider the progress that has been made in the last two decades in determining the fates of damaged organelles and damaged cells, through discrete, but genetically overlapping, pathways involving the selective autophagy and cell death machinery. We further discuss the ways in which the autophagy machinery may impact the clearance and consequences of dying cells for host physiology. Failure in the proper removal of damaged organelles and/or damaged cells by selective autophagy and cell death processes is likely to contribute to developmental abnormalities, cancer, aging, inflammation, and other diseases. PMID:24679527

  13. Heterogeneity in Oct4 and Sox2 Targets Biases Cell Fate in 4-Cell Mouse Embryos.

    PubMed

    Goolam, Mubeen; Scialdone, Antonio; Graham, Sarah J L; Macaulay, Iain C; Jedrusik, Agnieszka; Hupalowska, Anna; Voet, Thierry; Marioni, John C; Zernicka-Goetz, Magdalena

    2016-03-24

    The major and essential objective of pre-implantation development is to establish embryonic and extra-embryonic cell fates. To address when and how this fundamental process is initiated in mammals, we characterize transcriptomes of all individual cells throughout mouse pre-implantation development. This identifies targets of master pluripotency regulators Oct4 and Sox2 as being highly heterogeneously expressed between blastomeres of the 4-cell embryo, with Sox21 showing one of the most heterogeneous expression profiles. Live-cell tracking demonstrates that cells with decreased Sox21 yield more extra-embryonic than pluripotent progeny. Consistently, decreasing Sox21 results in premature upregulation of the differentiation regulator Cdx2, suggesting that Sox21 helps safeguard pluripotency. Furthermore, Sox21 is elevated following increased expression of the histone H3R26-methylase CARM1 and is lowered following CARM1 inhibition, indicating the importance of epigenetic regulation. Therefore, our results indicate that heterogeneous gene expression, as early as the 4-cell stage, initiates cell-fate decisions by modulating the balance of pluripotency and differentiation.

  14. Heterogeneity in Oct4 and Sox2 Targets Biases Cell Fate in 4-Cell Mouse Embryos.

    PubMed

    Goolam, Mubeen; Scialdone, Antonio; Graham, Sarah J L; Macaulay, Iain C; Jedrusik, Agnieszka; Hupalowska, Anna; Voet, Thierry; Marioni, John C; Zernicka-Goetz, Magdalena

    2016-03-24

    The major and essential objective of pre-implantation development is to establish embryonic and extra-embryonic cell fates. To address when and how this fundamental process is initiated in mammals, we characterize transcriptomes of all individual cells throughout mouse pre-implantation development. This identifies targets of master pluripotency regulators Oct4 and Sox2 as being highly heterogeneously expressed between blastomeres of the 4-cell embryo, with Sox21 showing one of the most heterogeneous expression profiles. Live-cell tracking demonstrates that cells with decreased Sox21 yield more extra-embryonic than pluripotent progeny. Consistently, decreasing Sox21 results in premature upregulation of the differentiation regulator Cdx2, suggesting that Sox21 helps safeguard pluripotency. Furthermore, Sox21 is elevated following increased expression of the histone H3R26-methylase CARM1 and is lowered following CARM1 inhibition, indicating the importance of epigenetic regulation. Therefore, our results indicate that heterogeneous gene expression, as early as the 4-cell stage, initiates cell-fate decisions by modulating the balance of pluripotency and differentiation. PMID:27015307

  15. The microRNA-dependent cell fate of multipotent stromal cells differentiating to endothelial cells.

    PubMed

    Cha, Min-Ji; Choi, Eunhyun; Lee, Seahyoung; Song, Byeong-Wook; Yoon, Cheesoon; Hwang, Ki-Chul

    2016-02-15

    In the endothelial recovery process, bone marrow-derived MSCs are a potential source of cells for both research and therapy, and their capacities to self-renew and to differentiate into all the cell types in the human body make them a promising therapeutic agent for remodeling cellular differentiation and a valuable resource for the treatment of many diseases. Based on the results provided in a miRNA database, we selected miRNAs with unique targets in cell fate-related signaling pathways. The tested miRNAs targeting GSK-3β (miR-26a), platelet-derived growth factor receptor, and CD133 (miR-26a and miR-29b) induced MSC differentiation into functional ECs, whereas miRNAs targeting VEGF receptor (miR-15, miR-144, miR-145, and miR-329) inhibited MSC differentiation into ECs through VEGF stimulation. In addition, the expression levels of these miRNAs were correlated with in vivo physiological endothelial recovery processes. These findings indicate that the miRNA expression profile is distinct for cells in different stages of differentiation from MSCs to ECs and that specific miRNAs can function as regulators of endothelialization.

  16. Stem cell decisions: a twist of fate or a niche market?

    PubMed

    Januschke, Jens; Näthke, Inke

    2014-10-01

    Establishing and maintaining cell fate in the right place at the right time is a key requirement for normal tissue maintenance. Stem cells are at the core of this process. Understanding how stem cells balance self-renewal and production of differentiating cells is key for understanding the defects that underpin many diseases. Both, external cues from the environment and cell intrinsic mechanisms can control the outcome of stem cell division. The role of the orientation of stem cell division has emerged as an important mechanism for specifying cell fate decisions. Although, the alignment of cell divisions can dependent on spatial cues from the environment, maintaining stemness is not always linked to positioning of stem cells in a particular microenvironment or `niche'. Alternate mechanisms that could contribute to cellular memory include differential segregation of centrosomes in asymmetrically dividing cells. PMID:24613913

  17. Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain.

    PubMed

    Pilaz, Louis-Jan; McMahon, John J; Miller, Emily E; Lennox, Ashley L; Suzuki, Aussie; Salmon, Edward; Silver, Debra L

    2016-01-01

    Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly. PMID:26748089

  18. Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain.

    PubMed

    Pilaz, Louis-Jan; McMahon, John J; Miller, Emily E; Lennox, Ashley L; Suzuki, Aussie; Salmon, Edward; Silver, Debra L

    2016-01-01

    Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly.

  19. Vacuolar H+-translocating inorganic pyrophosphatase (Vpp1) marks partial aleurone cell fate in cereal endosperm development.

    PubMed

    Wisniewski, Jean-Pierre; Rogowsky, Peter M

    2004-10-01

    Cereal endosperm is a model system for cell fate determination in plants. In wild-type plants the outermost endosperm cells adopt aleurone cell fate, while all underlying cells display starchy endosperm cell fate. Mutant analysis showed that cell fate is determined by position rather than lineage. To further characterise the precise cell fate of the outermost cells, we performed a differential screen and isolated the novel marker gene Vpp1 . It encodes a vacuolar H+-translocating inorganic pyrophosphatase (V-PPase) and is mainly expressed in kernels, leaves and tassels. In kernels, its expression is restricted to the aleurone layer with the maximum of expression shifting from the adaxial to the abaxial side during early stages. Together with three other marker genes Vpp1 was then used to analyse the cell fate of the outermost cells in Dap3 , Dap7 , cr4 and dek1 mutants, all of which have aberrant aleurone layers. In the Dap3 and Dap7 mutants the Vpp1 and Ltp2 markers but not the A1 and Zein markers were expressed in patches without aleurone indicating that the outermost cells had some but not all features of aleurone cells and did not simply adopt starchy endosperm cell fate. A similar result was obtained in the cr4 mutant, although Ltp2 expression was less generalised. In other Dap7 patches characterised by multiple aleurone-like cell layers the expression of Vpp1 and Ltp2 confirmed the aleurone cell fate of the cells in the additional cell layers. The analysis of dek1 mutants confirmed the starchy endosperm cell fate of the majority but not all outermost cells. Based on these data we propose a model suggesting a stepwise commitment to aleurone cell fate. Sequential steps are marked by the expression of Vpp1 , the expression of Ltp2 , the acquisition of a regular shape and thick walls and finally pigmentation coupled with A1 expression.

  20. Mammalian aPKC/Par polarity complex mediated regulation of epithelial division orientation and cell fate

    SciTech Connect

    Vorhagen, Susanne; Niessen, Carien M.

    2014-11-01

    Oriented cell division is a key regulator of tissue architecture and crucial for morphogenesis and homeostasis. Balanced regulation of proliferation and differentiation is an essential property of tissues not only to drive morphogenesis but also to maintain and restore homeostasis. In many tissues orientation of cell division is coupled to the regulation of differentiation producing daughters with similar (symmetric cell division, SCD) or differential fate (asymmetric cell division, ACD). This allows the organism to generate cell lineage diversity from a small pool of stem and progenitor cells. Division orientation and/or the ratio of ACD/SCD need to be tightly controlled. Loss of orientation or an altered ratio can promote overgrowth, alter tissue architecture and induce aberrant differentiation, and have been linked to morphogenetic diseases, cancer and aging. A key requirement for oriented division is the presence of a polarity axis, which can be established through cell intrinsic and/or extrinsic signals. Polarity proteins translate such internal and external cues to drive polarization. In this review we will focus on the role of the polarity complex aPKC/Par3/Par6 in the regulation of division orientation and cell fate in different mammalian epithelia. We will compare the conserved function of this complex in mitotic spindle orientation and distribution of cell fate determinants and highlight common and differential mechanisms in which this complex is used by tissues to adapt division orientation and cell fate to the specific properties of the epithelium.

  1. Mammalian aPKC/Par polarity complex mediated regulation of epithelial division orientation and cell fate.

    PubMed

    Vorhagen, Susanne; Niessen, Carien M

    2014-11-01

    Oriented cell division is a key regulator of tissue architecture and crucial for morphogenesis and homeostasis. Balanced regulation of proliferation and differentiation is an essential property of tissues not only to drive morphogenesis but also to maintain and restore homeostasis. In many tissues orientation of cell division is coupled to the regulation of differentiation producing daughters with similar (symmetric cell division, SCD) or differential fate (asymmetric cell division, ACD). This allows the organism to generate cell lineage diversity from a small pool of stem and progenitor cells. Division orientation and/or the ratio of ACD/SCD need to be tightly controlled. Loss of orientation or an altered ratio can promote overgrowth, alter tissue architecture and induce aberrant differentiation, and have been linked to morphogenetic diseases, cancer and aging. A key requirement for oriented division is the presence of a polarity axis, which can be established through cell intrinsic and/or extrinsic signals. Polarity proteins translate such internal and external cues to drive polarization. In this review we will focus on the role of the polarity complex aPKC/Par3/Par6 in the regulation of division orientation and cell fate in different mammalian epithelia. We will compare the conserved function of this complex in mitotic spindle orientation and distribution of cell fate determinants and highlight common and differential mechanisms in which this complex is used by tissues to adapt division orientation and cell fate to the specific properties of the epithelium.

  2. Thidiazuron Triggers Morphogenesis in Rosa canina L. Protocorm-Like Bodies by Changing Incipient Cell Fate

    PubMed Central

    Kou, Yaping; Yuan, Cunquan; Zhao, Qingcui; Liu, Guoqin; Nie, Jing; Ma, Zhimin; Cheng, Chenxia; Teixeira da Silva, Jaime A.; Zhao, Liangjun

    2016-01-01

    Thidiazuron (N-phenyl-N′-1,2,3-thiadiazol-5-ylurea; TDZ) is an artificial plant growth regulator that is widely used in plant tissue culture. Protocorm-like bodies (PLBs) induced by TDZ serve as an efficient and rapid in vitro regeneration system in Rosa species. Despite this, the mechanism of PLB induction remains relatively unclear. TDZ, which can affect the level of endogenous auxins and cytokinins, converts the cell fate of rhizoid tips and triggers PLB formation and plantlet regeneration in Rosa canina L. In callus-rhizoids, which are rhizoids that co-develop from callus, auxin and a Z-type cytokinin accumulated after applying TDZ, and transcription of the auxin transporter gene RcPIN1 was repressed. The expression of RcARF4, RcRR1, RcCKX2, RcCKX3, and RcLOG1 increased in callus-rhizoids and rhizoid tips while the transcription of an auxin response factor (RcARF1) and auxin transport proteins (RcPIN2, RcPIN3) decreased in callus-rhizoids but increased in rhizoid tips. In situ hybridization of rhizoids showed that RcWUS and RcSERK1 were highly expressed in columella cells and root stem cells resulting in the conversion of cell fate into shoot apical meristems or embryogenic callus. In addition, transgenic XVE::RcWUS lines showed repressed RcWUS overexpression while RcWUS had no effect on PLB morphogenesis. Furthermore, higher expression of the root stem cell marker RcWOX5 and root stem cell maintenance regulator genes RcPLT1 and RcPLT2 indicated the presence of a dedifferentiation developmental pathway in the stem cell niche of rhizoids. Viewed together, our results indicate that different cells in rhizoid tips acquired regeneration competence after induction by TDZ. A novel developmental pathway containing different cell types during PLB formation was identified by analyzing the endogenous auxin and cytokinin content. This study also provides a deeper understanding of the mechanisms underlying in vitro regeneration in Rosa. PMID:27200031

  3. Thidiazuron Triggers Morphogenesis in Rosa canina L. Protocorm-Like Bodies by Changing Incipient Cell Fate.

    PubMed

    Kou, Yaping; Yuan, Cunquan; Zhao, Qingcui; Liu, Guoqin; Nie, Jing; Ma, Zhimin; Cheng, Chenxia; Teixeira da Silva, Jaime A; Zhao, Liangjun

    2016-01-01

    Thidiazuron (N-phenyl-N'-1,2,3-thiadiazol-5-ylurea; TDZ) is an artificial plant growth regulator that is widely used in plant tissue culture. Protocorm-like bodies (PLBs) induced by TDZ serve as an efficient and rapid in vitro regeneration system in Rosa species. Despite this, the mechanism of PLB induction remains relatively unclear. TDZ, which can affect the level of endogenous auxins and cytokinins, converts the cell fate of rhizoid tips and triggers PLB formation and plantlet regeneration in Rosa canina L. In callus-rhizoids, which are rhizoids that co-develop from callus, auxin and a Z-type cytokinin accumulated after applying TDZ, and transcription of the auxin transporter gene RcPIN1 was repressed. The expression of RcARF4, RcRR1, RcCKX2, RcCKX3, and RcLOG1 increased in callus-rhizoids and rhizoid tips while the transcription of an auxin response factor (RcARF1) and auxin transport proteins (RcPIN2, RcPIN3) decreased in callus-rhizoids but increased in rhizoid tips. In situ hybridization of rhizoids showed that RcWUS and RcSERK1 were highly expressed in columella cells and root stem cells resulting in the conversion of cell fate into shoot apical meristems or embryogenic callus. In addition, transgenic XVE::RcWUS lines showed repressed RcWUS overexpression while RcWUS had no effect on PLB morphogenesis. Furthermore, higher expression of the root stem cell marker RcWOX5 and root stem cell maintenance regulator genes RcPLT1 and RcPLT2 indicated the presence of a dedifferentiation developmental pathway in the stem cell niche of rhizoids. Viewed together, our results indicate that different cells in rhizoid tips acquired regeneration competence after induction by TDZ. A novel developmental pathway containing different cell types during PLB formation was identified by analyzing the endogenous auxin and cytokinin content. This study also provides a deeper understanding of the mechanisms underlying in vitro regeneration in Rosa. PMID:27200031

  4. Cell-fate specification in the epidermis: a common patterning mechanism in the root and shoot.

    PubMed

    Schiefelbein, John

    2003-02-01

    The specification of epidermal hairs in Arabidopsis provides a useful model for the study of pattern formation in plants. Although the distributions of hair cells in the root and shoot appear quite different, recent studies show that pattern formation in each relies on a common cassette of transcriptional regulators. During development in each organ, neighboring cells compete to express regulators that specify the primary cell fate (including WEREWOLF [WER]/GLABRA1 [GL1], GL3/bHLH, TRANSPARENT TESTA GLABRA [TTG], and GL2), as well as those that prevent their neighbors from adopting this fate (including CAPRICE [CPC] and TRIPTYCHON [TRY]). The basic mechanism of lateral inhibition with feedback that has been uncovered by recent studies provides a conceptual framework for understanding how patterns of cell fate in general may be specified during plant development.

  5. Surface position, not signaling from surrounding maternal tissues, specifies aleurone epidermal cell fate in maize.

    PubMed

    Gruis, Darren Fred; Guo, Hena; Selinger, David; Tian, Qing; Olsen, Odd-Arne

    2006-07-01

    Maize (Zea mays) endosperm consists of an epidermal-like surface layer of aleurone cells, an underlying body of starchy endosperm cells, and a basal layer of transfer cells. To determine whether surrounding maternal tissues perform a role in specifying endosperm cell fates, a maize endosperm organ culture technique was established whereby the developing endosperm is completely removed from surrounding maternal tissues. Using cell type-specific fluorescence markers, we show that aleurone cell fate specification occurs exclusively in response to surface position and does not require specific, continued maternal signal input. The starchy endosperm and aleurone cell fates are freely interchangeable throughout the lifespan of the endosperm, with internalized aleurone cells converting to starchy endosperm cells and with starchy endosperm cells that become positioned at the surface converting to aleurone cells. In contrast to aleurone and starchy endosperm cells, transfer cells fail to develop in in vitro-grown endosperm, supporting earlier indications that maternal tissue interaction is required to fully differentiate this cell type. Several parameters confirm that the maize endosperm organ cultures described herein retain the main developmental features of in planta endosperm, including fidelity of aleurone mutant phenotypes, temporal and spatial control of cell type-specific fluorescent markers, specificity of cell type transcripts, and control of mitotic cell divisions.

  6. Deep sequencing as a probe of normal stem cell fate and preneoplasia in human epidermis

    PubMed Central

    Simons, Benjamin D.

    2016-01-01

    Using deep sequencing technology, methods based on the sporadic acquisition of somatic DNA mutations in human tissues have been used to trace the clonal evolution of progenitor cells in diseased states. However, the potential of these approaches to explore cell fate behavior of normal tissues and the initiation of preneoplasia remain underexploited. Focusing on the results of a recent deep sequencing study of eyelid epidermis, we show that the quantitative analysis of mutant clone size provides a general method to resolve the pattern of normal stem cell fate and to detect and characterize the mutational signature of rare field transformations in human tissues, with implications for the early detection of preneoplasia. PMID:26699486

  7. Identification of the Molecular Mechanisms for Cell-Fate Selection in Budding Yeast through Mathematical Modeling

    PubMed Central

    Li, Yongkai; Yi, Ming; Zou, Xiufen

    2013-01-01

    The specification and maintenance of cell fates is essential to the development of multicellular organisms. However, the precise molecular mechanisms in cell fate selection are, to our knowledge, poorly understood due to the complexity of multiple interconnected pathways. In this study, model-based quantitative analysis is used to explore how to maintain distinguished cell fates between cell-cycle commitment and mating arrest in budding yeast. We develop a full mathematical model of an interlinked regulatory network based on the available experimental data. By theoretically defining the Start transition point, the model is able to reproduce many experimental observations of the dynamical behaviors in wild-type cells as well as in Ste5-8A and Far1-S87A mutants. Furthermore, we demonstrate that a moderate ratio between Cln1/2→Far1 inhibition and Cln1/2→Ste5 inhibition is required to ensure a successful switch between different cell fates. We also show that the different ratios of the mutual Cln1/2 and Far1 inhibition determine the different cell fates. In addition, based on a new, definition of network entropy, we find that the Start point in wild-type cells coincides with the system’s point of maximum entropy. This result indicates that Start is a transition point in the network entropy. Therefore, we theoretically explain the Start point from a network dynamics standpoint. Moreover, we analyze the biological bistablity of our model through bifurcation analysis. We find that the Cln1/2 and Cln3 production rates and the nonlinearity of SBF regulation on Cln1/2 production are potential determinants for irreversible entry into a new cell fate. Finally, the quantitative computations further reveal that high specificity and fidelity of the cell-cycle and mating pathways can guarantee specific cell-fate selection. These findings show that quantitative analysis and simulations with a mathematical model are useful tools for understanding the molecular mechanisms in

  8. A blueprint for engineering cell fate: current technologies to reprogram cell identity

    PubMed Central

    Morris, Samantha A; Daley, George Q

    2013-01-01

    Human diseases such as heart failure, diabetes, neurodegenerative disorders, and many others result from the deficiency or dysfunction of critical cell types. Strategies for therapeutic tissue repair or regeneration require the in vitro manufacture of clinically relevant quantities of defined cell types. In addition to transplantation therapy, the generation of otherwise inaccessible cells also permits disease modeling, toxicology testing and drug discovery in vitro. In this review, we discuss current strategies to manipulate the identity of abundant and accessible cells by differentiation from an induced pluripotent state or direct conversion between differentiated states. We contrast these approaches with recent advances employing partial reprogramming to facilitate lineage switching, and discuss the mechanisms underlying the engineering of cell fate. Finally, we address the current limitations of the field and how the resulting cell types can be assessed to ensure the production of medically relevant populations. PMID:23277278

  9. Ngn3+ endocrine progenitor cells control the fate and morphogenesis of pancreatic ductal epithelium

    PubMed Central

    Magenheim, Judith; Klein, Allon M.; Stanger, Ben Z.; Ashery-Padan, Ruth; Sosa-Pineda, Beatriz; Gu, Guoqiang; Dor, Yuval

    2013-01-01

    Summary During pancreas development, endocrine and exocrine cells arise from a common multipotent progenitor pool. How these cell fate decisions are coordinated with tissue morphogenesis is poorly understood. Here we have examined ductal morphology, endocrine progenitor cell fate and Notch signaling in Ngn3−/− mice, which do not produce islet cells. Ngn3 deficiency results in reduced branching and enlarged pancreatic duct-like structures, concomitant with Ngn3 promoter activation throughout the ductal epithelium and reduced Notch signaling. Conversely, forced generation of surplus endocrine progenitor cells causes reduced duct caliber and an excessive number of tip cells. Thus, endocrine progenitor cells normally provide a feedback signal to adjacent multipotent ductal progenitor cells that activates Notch signaling, inhibits further endocrine differentiation and promotes proper morphogenesis. These results uncover a novel layer of regulation coordinating pancreas morphogenesis and endocrine/exocrine differentiation, and suggest ways to enhance the yield of beta-cells from stem cells. PMID:21888903

  10. Tissue-specific targeting of cell fate regulatory genes by E2f factors.

    PubMed

    Julian, L M; Liu, Y; Pakenham, C A; Dugal-Tessier, D; Ruzhynsky, V; Bae, S; Tsai, S-Y; Leone, G; Slack, R S; Blais, A

    2016-04-01

    Cell cycle proteins are important regulators of diverse cell fate decisions, and in this capacity have pivotal roles in neurogenesis and brain development. The mechanisms by which cell cycle regulation is integrated with cell fate control in the brain and other tissues are poorly understood, and an outstanding question is whether the cell cycle machinery regulates fate decisions directly or instead as a secondary consequence of proliferative control. Identification of the genes targeted by E2 promoter binding factor (E2f) transcription factors, effectors of the pRb/E2f cell cycle pathway, will provide essential insights into these mechanisms. We identified the promoter regions bound by three neurogenic E2f factors in neural precursor cells in a genome-wide manner. Through bioinformatic analyses and integration of published genomic data sets we uncovered hundreds of transcriptionally active E2f-bound promoters corresponding to genes that control cell fate processes, including key transcriptional regulators and members of the Notch, fibroblast growth factor, Wnt and Tgf-β signaling pathways. We also demonstrate a striking enrichment of the CCCTC binding factor transcription factor (Ctcf) at E2f3-bound nervous system-related genes, suggesting a potential regulatory co-factor for E2f3 in controlling differentiation. Finally, we provide the first demonstration of extensive tissue specificity among E2f target genes in mammalian cells, whereby E2f3 promoter binding is well conserved between neural and muscle precursors at genes associated with cell cycle processes, but is tissue-specific at differentiation-associated genes. Our findings implicate the cell cycle pathway as a widespread regulator of cell fate genes, and suggest that E2f3 proteins control cell type-specific differentiation programs by regulating unique sets of target genes. This work significantly enhances our understanding of how the cell cycle machinery impacts cell fate and differentiation, and will

  11. NOTCH activation interferes with cell fate specification in the gastrulating mouse embryo.

    PubMed

    Souilhol, Céline; Perea-Gomez, Aitana; Camus, Anne; Beck-Cormier, Sarah; Vandormael-Pournin, Sandrine; Escande, Marie; Collignon, Jérôme; Cohen-Tannoudji, Michel

    2015-11-01

    NOTCH signalling is an evolutionarily conserved pathway involved in intercellular communication essential for cell fate choices during development. Although dispensable for early aspects of mouse development, canonical RBPJ-dependent NOTCH signalling has been shown to influence lineage commitment during embryonic stem cell (ESC) differentiation. NOTCH activation in ESCs promotes the acquisition of a neural fate, whereas its suppression favours their differentiation into cardiomyocytes. This suggests that NOTCH signalling is implicated in the acquisition of distinct embryonic fates at early stages of mammalian development. In order to investigate in vivo such a role for NOTCH signalling in shaping cell fate specification, we use genetic approaches to constitutively activate the NOTCH pathway in the mouse embryo. Early embryonic development, including the establishment of anterior-posterior polarity, is not perturbed by forced NOTCH activation. By contrast, widespread NOTCH activity in the epiblast triggers dramatic gastrulation defects. These are fully rescued in a RBPJ-deficient background. Epiblast-specific NOTCH activation induces acquisition of neurectoderm identity and disrupts the formation of specific mesodermal precursors including the derivatives of the anterior primitive streak, the mouse organiser. In addition, we show that forced NOTCH activation results in misregulation of NODAL signalling, a major determinant of early embryonic patterning. Our study reveals a previously unidentified role for canonical NOTCH signalling during mammalian gastrulation. It also exemplifies how in vivo studies can shed light on the mechanisms underlying cell fate specification during in vitro directed differentiation.

  12. New roles for Nanos in neural cell fate determination revealed by studies in a cnidarian.

    PubMed

    Kanska, Justyna; Frank, Uri

    2013-07-15

    Nanos is a pan-metazoan germline marker, important for germ cell development and maintenance. In flies, Nanos also acts in posterior and neural development, but these functions have not been demonstrated experimentally in other animals. Using the cnidarian Hydractinia we have uncovered novel roles for Nanos in neural cell fate determination. Ectopic expression of Nanos2 increased the numbers of embryonic stinging cell progenitors, but decreased the numbers of neurons. Downregulation of Nanos2 had the opposite effect. Furthermore, Nanos2 blocked maturation of committed, post-mitotic nematoblasts. Hence, Nanos2 acts as a switch between two differentiation pathways, increasing the numbers of nematoblasts at the expense of neuroblasts, but preventing nematocyte maturation. Nanos2 ectopic expression also caused patterning defects, but these were not associated with deregulation of Wnt signaling, showing that the basic anterior-posterior polarity remained intact, and suggesting that numerical imbalance between nematocytes and neurons might have caused these defects, affecting axial patterning only indirectly. We propose that the functions of Nanos in germ cells and in neural development are evolutionarily conserved, but its role in posterior patterning is an insect or arthropod innovation. PMID:23659997

  13. Eafs Control Erythroid Cell Fate by Regulating c-myb Expression through Wnt Signaling

    PubMed Central

    Ma, Xufa; Liu, Jing-Xia

    2013-01-01

    ELL associated factor 1 and ELL associated factor 2 (EAF1/2 factors) are reported to play important roles in tumor suppression and embryogenesis. Our previous studies showed that eaf factors mediated effective convergence and extension (C&E) movements and modulated mesoderm and neural patterning by regulating both non-canonical and canonical Wnt signaling in the early embryonic process. In this study, through knockdown of both eaf1 and eaf2 in embryos, we found that differentiation of primary erythroid cells was blocked, but hematopoietic precursor cells maintained in eafs morphants. Co-injection of c-myb-MO rescued the erythroid differentiation in eafs morphants, as indicated by the restored expression of the erythroid-specific gene, βe3 globin. In addition, low dosage of c-myb effectively blocked the βe3 globin expression in embryos, and did not affect the expression of markers of hematopoietic progenitor cells and other mesoderm, which was similar to the phenotypes we observed in eafs morphants. We also revealed that knockdown Wnt signaling by transiently inducing dn-Tcf in embryos at the bud stage down-regulated the increased c-myb to normal level and also restored βe3 globin expression in eafs morphants. Our evidence points to a novel role for eaf factors in controlling erythroid cell fate by regulating c-Myb expression through canonic Wnt signaling. PMID:23717633

  14. New roles for Nanos in neural cell fate determination revealed by studies in a cnidarian.

    PubMed

    Kanska, Justyna; Frank, Uri

    2013-07-15

    Nanos is a pan-metazoan germline marker, important for germ cell development and maintenance. In flies, Nanos also acts in posterior and neural development, but these functions have not been demonstrated experimentally in other animals. Using the cnidarian Hydractinia we have uncovered novel roles for Nanos in neural cell fate determination. Ectopic expression of Nanos2 increased the numbers of embryonic stinging cell progenitors, but decreased the numbers of neurons. Downregulation of Nanos2 had the opposite effect. Furthermore, Nanos2 blocked maturation of committed, post-mitotic nematoblasts. Hence, Nanos2 acts as a switch between two differentiation pathways, increasing the numbers of nematoblasts at the expense of neuroblasts, but preventing nematocyte maturation. Nanos2 ectopic expression also caused patterning defects, but these were not associated with deregulation of Wnt signaling, showing that the basic anterior-posterior polarity remained intact, and suggesting that numerical imbalance between nematocytes and neurons might have caused these defects, affecting axial patterning only indirectly. We propose that the functions of Nanos in germ cells and in neural development are evolutionarily conserved, but its role in posterior patterning is an insect or arthropod innovation.

  15. Curcumin regulates cell fate and metabolism by inhibiting hedgehog signaling in hepatic stellate cells.

    PubMed

    Lian, Naqi; Jiang, Yuanyuan; Zhang, Feng; Jin, Huanhuan; Lu, Chunfeng; Wu, Xiafei; Lu, Yin; Zheng, Shizhong

    2015-07-01

    Accumulating evidence indicates that Hedgehog (Hh) signaling becomes activated in chronic liver injury and plays a role in the pathogenesis of hepatic fibrosis. Hepatic stellate cells (HSCs) are Hh-responsive cells and activation of the Hh pathway promotes transdifferentiation of HSCs into myofibroblasts. Targeting Hh signaling may be a novel therapeutic strategy for treatment of liver fibrosis. We previously reported that curcumin has potent antifibrotic effects in vivo and in vitro, but the underlying mechanisms are not fully elucidated. This study shows that curcumin downregulated Patched and Smoothened, two key elements in Hh signaling, but restored Hhip expression in rat liver with carbon tetrachloride-induced fibrosis and in cultured HSCs. Curcumin also halted the nuclear translocation, DNA binding, and transcription activity of Gli1. Moreover, the Hh signaling inhibitor cyclopamine, like curcumin, arrested the cell cycle, induced mitochondrial apoptosis, reduced fibrotic gene expression, restored lipid accumulation, and inhibited invasion and migration in HSCs. However, curcumin's effects on cell fate and fibrogenic properties of HSCs were abolished by the Hh pathway agonist SAG. Furthermore, curcumin and cyclopamine decreased intracellular levels of adenosine triphosphate and lactate, and inhibited the expression and/or function of several key molecules controlling glycolysis. However, SAG abrogated the curcumin effects on these parameters of glycolysis. Animal data also showed that curcumin downregulated glycolysis-regulatory proteins in rat fibrotic liver. These aggregated data therefore indicate that curcumin modulated cell fate and metabolism by disrupting the Hh pathway in HSCs, providing novel molecular insights into curcumin reduction of HSC activation.

  16. Revealing the fate of cell surface human P-glycoprotein (ABCB1): The lysosomal degradation pathway.

    PubMed

    Katayama, Kazuhiro; Kapoor, Khyati; Ohnuma, Shinobu; Patel, Atish; Swaim, William; Ambudkar, Indu S; Ambudkar, Suresh V

    2015-10-01

    P-glycoprotein (P-gp) transports a variety of chemically dissimilar amphipathic compounds including anticancer drugs. Although mechanisms of P-gp drug transport are widely studied, the pathways involving its internalization are poorly understood. The present study is aimed at elucidating the pathways involved in degradation of cell surface P-gp. The fate of P-gp at the cell surface was determined by biotinylating cell surface proteins followed by flow cytometry and Western blotting. Our data shows that the half-life of endogenously expressed P-gp is 26.7±1.1 h in human colorectal cancer HCT-15 cells. Treatment of cells with Bafilomycin A1 (BafA1) a vacuolar H+ ATPase inhibitor increased the half-life of P-gp at the cell surface to 36.1±0.5 h. Interestingly, treatment with the proteasomal inhibitors MG132, MG115 or lactacystin alone did not alter the half-life of the protein. When cells were treated with both lysosomal and proteasomal inhibitors (BafA1 and MG132), the half-life was further prolonged to 39-50 h. Functional assays done with rhodamine 123 or calcein-AM, fluorescent substrates of P-gp, indicated that the transport function of P-gp was not affected by either biotinylation or treatment with BafA1 or proteasomal inhibitors. Immunofluorescence studies done with the antibody against lysosomal marker LAMP1 and the P-gp-specific antibody UIC2 in permeabilized cells indicated that intracellular P-gp is primarily localized in the lysosomal compartment. Our results suggest that the lysosomal degradation system could be targeted to increase the sensitivity of P-gp- expressing cancer cells towards chemotherapeutic drugs.

  17. Microenvironmental control of stem cell fate in intestinal homeostasis and disease.

    PubMed

    Biswas, Sujata; Davis, Hayley; Irshad, Shazia; Sandberg, Tessa; Worthley, Daniel; Leedham, Simon

    2015-10-01

    The conventional model of intestinal epithelial architecture describes a unidirectional tissue organizational hierarchy with stem cells situated at the crypt base and daughter cells proliferating and terminally differentiating as they progress along the vertical (crypt-luminal) axis. In this model, the fate of a cell that has left the niche is determined and its lifespan limited. Evidence is accumulating to suggest that stem cell control and daughter cell fate determination is not solely an intrinsic, cell autonomous property but is heavily influenced by the microenvironment including paracrine, mesenchymal, and endogenous epithelial morphogen gradients. Recent research suggests that in intestinal homeostasis, stem cells transit reversibly between states of variable competence in the niche. Furthermore, selective pressures that disrupt the homeostatic balance, such as intestinal inflammation or morphogen dysregulation, can cause committed progenitor cells and even some differentiated cells to regain stem cell properties. Importantly, it has been recently shown that this disruption of cell fate determination can lead to somatic mutation and neoplastic transformation of cells situated outside the crypt base stem cell niche. This paper reviews the exciting developments in the study of stem cell dynamics in homeostasis, intestinal regeneration, and carcinogenesis, and explores the implications for human disease and cancer therapies.

  18. Steroids are required for epidermal cell fate establishment in Arabidopsis roots.

    PubMed

    Kuppusamy, Kavitha T; Chen, Andrew Y; Nemhauser, Jennifer L

    2009-05-12

    The simple structure of Arabidopsis roots provides an excellent model system to study epidermal cell fate specification. Epidermal cells in contact with 2 underlying cortical cells differentiate into hair cells (H cells; trichoblasts), whereas cells that contact only a single cortical cell differentiate into mature hairless cells (N cells; atrichoblasts). This position-dependent patterning, in combination with the constrained orientation of cell divisions, results in hair and nonhair cell files running longitudinally along the root epidermis. Here, we present strong evidence that steroid hormones called brassinosteroids (BRs) are required to maintain position-dependent fate specification in roots. We show that BRs are required for normal expression levels and patterns of WEREWOLF (WER) and GLABRA2 (GL2), master regulators of epidermal patterning. Loss of BR signaling results in loss of hair cells in H positions, likely as a consequence of reduced expression of CAPRICE (CPC), a direct downstream target of WER. Our observations demonstrate that in addition to their well-known role in cell expansion, BRs play an essential role in directing cell fate.

  19. β‐catenin‐driven binary cell fate decisions in animal development

    PubMed Central

    2016-01-01

    The Wnt/β‐catenin pathway plays key roles during animal development. In several species, β‐catenin is used in a reiterative manner to regulate cell fate diversification between daughter cells following division. This binary cell fate specification mechanism has been observed in animals that belong to very diverse phyla: the nematode Caenorhabditis elegans, the annelid Platynereis, and the ascidian Ciona. It may also play a role in the regulation of several stem cell lineages in vertebrates. While the molecular mechanism behind this binary cell fate switch is not fully understood, it appears that both secreted Wnt ligands and asymmetric cortical factors contribute to the generation of the difference in nuclear β‐catenin levels between daughter cells. β‐Catenin then cooperates with lineage specific transcription factors to induce the expression of novel sets of transcription factors at each round of divisions, thereby diversifying cell fate. WIREs Dev Biol 2016, 5:377–388. doi: 10.1002/wdev.228 For further resources related to this article, please visit the WIREs website. PMID:26952169

  20. Toying with fate: Redirecting the differentiation of adrenocortical progenitor cells into gonadal-like tissue

    PubMed Central

    Röhrig, Theresa; Pihlajoki, Marjut; Ziegler, Ricarda; Cochran, Rebecca S.; Schrade, Anja; Schillebeeckx, Maximiliaan; Mitra, Robi D.; Heikinheimo, Markku; Wilson, David B.

    2014-01-01

    Cell fate decisions are integral to zonation and remodeling of the adrenal cortex. Animal models exhibiting ectopic differentiation of gonadal-like cells in the adrenal cortex can shed light on the molecular mechanisms regulating steroidogenic cell fate. In one such model, prepubertal gonadectomy (GDX) of mice triggers the formation of adrenocortical neoplasms that resemble luteinized ovarian stroma. Transcriptomic analysis and genome-wide DNA methylation mapping have identified genetic and epi-genetic markers of GDX-induced adrenocortical neoplasia. Members of the GATA transcription factor family have emerged as key regulators of cell fate in this model. Expression of Gata4 is pivotal for the accumulation of gonadal-like cells in the adrenal glands of gonadectomized mice, whereas expression of Gata6 limits the spontaneous and GDX-induced differentiation of gonadal-like cells in the adrenal cortex. Additionally, Gata6 is essential for proper development of the adrenal X-zone, a layer analogous to the fetal zone of the human adrenal cortex. The relevance of these observations to developmental signaling pathways in the adrenal cortex, to other animal models of altered adrenocortical cell fate, and to human diseases is discussed. PMID:25498963

  1. Cell fate in the Arabidopsis root epidermis is determined by competition between WEREWOLF and CAPRICE.

    PubMed

    Song, Sang-Kee; Ryu, Kook Hui; Kang, Yeon Hee; Song, Jae Hyo; Cho, Young-Hee; Yoo, Sang-Dong; Schiefelbein, John; Lee, Myeong Min

    2011-11-01

    The root hair and nonhair cells in the Arabidopsis (Arabidopsis thaliana) root epidermis are specified by a suite of transcriptional regulators. Two of these are WEREWOLF (WER) and CAPRICE (CPC), which encode MYB transcription factors that are required for promoting the nonhair cell fate and the hair cell fate, respectively. However, the precise function and relationship between these transcriptional regulators have not been fully defined experimentally. Here, we examine these issues by misexpressing the WER gene using the GAL4-upstream activation sequence transactivation system. We find that WER overexpression in the Arabidopsis root tip is sufficient to cause epidermal cells to adopt the nonhair cell fate through direct induction of GLABRA2 (GL2) gene expression. We also show that GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), two closely related bHLH proteins, are required for the action of the overexpressed WER and that WER interacts with these bHLHs in plant cells. Furthermore, we find that CPC suppresses the WER overexpression phenotype quantitatively. These results show that WER acts together with GL3/EGL3 to induce GL2 expression and that WER and CPC compete with one another to define cell fates in the Arabidopsis root epidermis.

  2. The fog-3 gene and regulation of cell fate in the germ line of Caenorhabditis elegans

    SciTech Connect

    Ellis, R.; Kimble, J.

    1995-02-01

    In the nematode Caenorhabditis elegans, germ cells normally adopt one of three fates: mitosis, spermatogenesis or oogenesis. We have identified and characterized the gene fog-3, which is required for germ cells to differentiate as sperm rather than as oocytes. Analysis of double mutants suggests that fog-3 is absolutely required for spermatogenesis and acts at the end of the regulatory hierarchy controlling sex determination for the germ line. By contrast, mutations in fog-3 do not alter the sexual identity of other tissues. We also have characterized the null phenotype of fog-1, another gene required for spermatogenesis; we demonstrate that it too controls the sexual identity of germ cells but not of other tissues. Finally, we have studied the same interaction of these two fog genes with gld-1, a gene required for germ cells to undergo oogenesis rather than mitosis. On the basis of these results, we propose that germ-cell fate might be controlled by a set of inhibitory interactions among genes that specify one of three fates: mitosis, spermatogenesis or oogenesis. Such a regulatory network would link the adoption of one germ-cell fate to the suppression of the other two. 68 refs., 7 figs., 6 tabs.

  3. Logic programming to predict cell fate patterns and retrodict genotypes in organogenesis.

    PubMed

    Hall, Benjamin A; Jackson, Ethan; Hajnal, Alex; Fisher, Jasmin

    2014-09-01

    Caenorhabditis elegans vulval development is a paradigm system for understanding cell differentiation in the process of organogenesis. Through temporal and spatial controls, the fate pattern of six cells is determined by the competition of the LET-23 and the Notch signalling pathways. Modelling cell fate determination in vulval development using state-based models, coupled with formal analysis techniques, has been established as a powerful approach in predicting the outcome of combinations of mutations. However, computing the outcomes of complex and highly concurrent models can become prohibitive. Here, we show how logic programs derived from state machines describing the differentiation of C. elegans vulval precursor cells can increase the speed of prediction by four orders of magnitude relative to previous approaches. Moreover, this increase in speed allows us to infer, or 'retrodict', compatible genomes from cell fate patterns. We exploit this technique to predict highly variable cell fate patterns resulting from dig-1 reduced-function mutations and let-23 mosaics. In addition to the new insights offered, we propose our technique as a platform for aiding the design and analysis of experimental data.

  4. Fate and metabolism of the brominated flame retardant tetrabromobisphenol A (TBBPA) in rice cell suspension culture.

    PubMed

    Wang, Songfeng; Cao, Siqi; Wang, Yongfeng; Jiang, Bingqi; Wang, Lianhong; Sun, Feifei; Ji, Rong

    2016-07-01

    Tetrabromobisphenol A (TBBPA) is the brominated flame retardant with the highest production volume and its bioaccumulation in environment has caused both human health and environmental concerns, however the fate and metabolism of TBBPA in plants is unknown. We studied the fate, metabolites, and transformation of (14)C-labeled TBBPA in rice cell suspension culture. During the incubation for 14 days, TBBPA degradation occurred continuously in the culture, accompanied by formation of one anisolic metabolite [2,6-dibromo-4-(2-(2-hydroxy)-propyl)-anisole] (DBHPA) (50% of the degraded TBBPA) and cellular debris-bound residues (46.4%) as well as mineralization (3.6%). The cells continuously accumulated TBBPA in the cytoplasm, while a small amount of DBHPA (2.1% of the initially applied TBBPA) was detectable inside the cells only at the end of incubation. The majority of the accumulated residues in the cells was attributed to the cellular debris-bound residues, accounting for 70-79% of the accumulation after the first incubation day. About 5.4% of the accumulation was associated with cell organelles, which contributed 7.5% to the cellular debris-bound residues. Based on the fate and metabolism of TBBPA in the rice cell suspension culture, a type II ipso-substitution pathway was proposed to describe the initial step for TBBPA degradation in the culture and balance the fate of TBBPA in the cells. To the best of our knowledge, our study provides for the first time the insights into the fate and metabolism of TBBPA in plants and points out the potential role of type II ipso-hydroxylation substitution in degradation of alkylphenols in plants. Further studies are required to reveal the mechanisms for the bound-residue formation (e.g., binding of residues to specific cell wall components), nature of the binding, and toxicological effects of the bound residues and DBHPA.

  5. Nanotopographical Surfaces for Stem Cell Fate Control: Engineering Mechanobiology from the Bottom

    PubMed Central

    Chen, Weiqiang; Shao, Yue; Li, Xiang; Zhao, Gang; Fu, Jianping

    2015-01-01

    Summary During embryogenesis and tissue maintenance and repair in an adult organism, a myriad of stem cells are regulated by their surrounding extracellular matrix (ECM) enriched with tissue/organ-specific nanoscale topographical cues to adopt different fates and functions. Attributed to their capability of self-renewal and differentiation into most types of somatic cells, stem cells also hold tremendous promise for regenerative medicine and drug screening. However, a major challenge remains as to achieve fate control of stem cells in vitro with high specificity and yield. Recent exciting advances in nanotechnology and materials science have enabled versatile, robust, and large-scale stem cell engineering in vitro through developments of synthetic nanotopographical surfaces mimicking topological features of stem cell niches. In addition to generating new insights for stem cell biology and embryonic development, this effort opens up unlimited opportunities for innovations in stem cell-based applications. This review is therefore to provide a summary of recent progress along this research direction, with perspectives focusing on emerging methods for generating nanotopographical surfaces and their applications in stem cell research. Furthermore, we provide a review of classical as well as emerging cellular mechano-sensing and -transduction mechanisms underlying stem cell nanotopography sensitivity and also give some hypotheses in regard to how a multitude of signaling events in cellular mechanotransduction may converge and be integrated into core pathways controlling stem cell fate in response to extracellular nanotopography. PMID:25883674

  6. Early postnatal respiratory viral infection alters hippocampal neurogenesis, cell fate, and neuron morphology in the neonatal piglet.

    PubMed

    Conrad, Matthew S; Harasim, Samantha; Rhodes, Justin S; Van Alstine, William G; Johnson, Rodney W

    2015-02-01

    Respiratory viral infections are common during the neonatal period in humans, but little is known about how early-life infection impacts brain development. The current study used a neonatal piglet model as piglets have a gyrencephalic brain with growth and development similar to human infants. Piglets were inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) to evaluate how chronic neuroinflammation affects hippocampal neurogenesis and neuron morphology. Piglets in the neurogenesis study received one bromodeoxyuridine injection on postnatal day (PD) 7 and then were inoculated with PRRSV. Piglets were sacrificed at PD 28 and the number of BrdU+ cells and cell fate were quantified in the dentate gyrus. PRRSV piglets showed a 24% reduction in the number of newly divided cells forming neurons. Approximately 15% of newly divided cells formed microglia, but this was not affected by sex or PRRSV. Additionally, there was a sexual dimorphism of new cell survival in the dentate gyrus where males had more cells than females, and PRRSV infection caused a decreased survival in males only. Golgi impregnation was used to characterize dentate granule cell morphology. Sholl analysis revealed that PRRSV caused a change in inner granule cell morphology where the first branch point was extended further from the cell body. Males had more complex dendritic arbors than females in the outer granule cell layer, but this was not affected by PRRSV. There were no changes to dendritic spine density or morphology distribution. These findings suggest that early-life viral infection can impact brain development.

  7. Concise Review: Control of Cell Fate Through Cell Cycle and Pluripotency Networks.

    PubMed

    Boward, Ben; Wu, Tianming; Dalton, Stephen

    2016-06-01

    Pluripotent stem cells (PSCs) proliferate rapidly with a characteristic cell cycle structure consisting of short G1- and G2-gap phases. This applies broadly to PSCs of peri-implantation stage embryos, cultures of embryonic stem cells, induced pluripotent stem cells, and embryonal carcinoma cells. During the early stages of PSC differentiation however, cell division times increase as a consequence of cell cycle remodeling. Most notably, this is indicated by elongation of the G1-phase. Observations linking changes in the cell cycle with exit from pluripotency have raised questions about the role of cell cycle control in maintenance of the pluripotent state. Until recently however, this has been a difficult question to address because of limitations associated with experimental tools. Recent studies now show that pluripotency and cell cycle regulatory networks are intertwined and that cell cycle control mechanisms are an integral, mechanistic part of the PSC state. Studies in embryonal carcinoma, some 30 years ago, first suggested that pluripotent cells initiate differentiation when in the G1-phase. More recently, a molecular "priming" mechanism has been proposed to explain these observations in human embryonic stem cells. Complexity in this area has been increased by the realization that pluripotent cells exist in multiple developmental states and that in addition to each having their own characteristic gene expression and epigenetic signatures, they potentially have alternate modes of cell cycle regulation. This review will summarize current knowledge in these areas and will highlight important aspects of interconnections between the cell cycle, self-renewal, pluripotency, and cell fate decisions. Stem Cells 2016;34:1427-1436.

  8. Antigen availability determines CD8+ T cell-dendritic cell interaction kinetics and memory fate decisions

    PubMed Central

    Henrickson, Sarah E.; Stutte, Susanne; Quigley, Michael; Alexe, Gabriela; Iannacone, Matteo; Flynn, Michael P.; Omid, Shaida; Jesneck, Jonathan L.; Imam, Sabrina; Mempel, Thorsten R.; Mazo, Irina B.; Haining, William N.; von Andrian, Ulrich H.

    2014-01-01

    Summary T cells are activated by antigen (Ag) bearing dendritic cells (DCs) in lymph nodes in 3 phases. The duration of the initial phase of transient, serial DC-T cell interactions is inversely correlated with Ag dose. The second phase, characterized by stable DC-T cell contacts, is believed to be necessary for full-fledged T cell activation. Here we have shown that this is not the case. CD8+ T cells interacting with DCs presenting low-dose, short-lived Ag did not transition to phase 2, while higher Ag dose yielded phase 2 transition. Both antigenic constellations promoted T cell proliferation and effector differentiation, but yielded different transcriptome signatures at 12h and 24h. T cells that experienced phase 2 developed long-lived memory, whereas conditions without stable contacts yielded immunological amnesia. Thus, T cells make fate decisions within hours after Ag exposure resulting in long-term memory or abortive effector responses, correlating with T cell-DCs interaction kinetics. PMID:24054328

  9. Drosophila Condensin II subunit Chromosome-associated protein D3 regulates cell fate determination through non-cell-autonomous signaling

    PubMed Central

    Klebanow, Lindsey R.; Peshel, Emanuela C.; Schuster, Andrew T.; De, Kuntal; Sarvepalli, Kavitha; Lemieux, Madeleine E.; Lenoir, Jessica J.; Moore, Adrian W.; McDonald, Jocelyn A.

    2016-01-01

    The pattern of the Drosophila melanogaster adult wing is heavily influenced by the expression of proteins that dictate cell fate decisions between intervein and vein during development. dSRF (Blistered) expression in specific regions of the larval wing disc promotes intervein cell fate, whereas EGFR activity promotes vein cell fate. Here, we report that the chromatin-organizing protein CAP-D3 acts to dampen dSRF levels at the anterior/posterior boundary in the larval wing disc, promoting differentiation of cells into the anterior crossvein. CAP-D3 represses KNOT expression in cells immediately adjacent to the anterior/posterior boundary, thus blocking KNOT-mediated repression of EGFR activity and preventing cell death. Maintenance of EGFR activity in these cells depresses dSRF levels in the neighboring anterior crossvein progenitor cells, allowing them to differentiate into vein cells. These findings uncover a novel transcriptional regulatory network influencing Drosophila wing vein development, and are the first to identify a Condensin II subunit as an important regulator of EGFR activity and cell fate determination in vivo. PMID:27317808

  10. A germline GFP transgenic axolotl and its use to track cell fate: dual origin of the fin mesenchyme during development and the fate of blood cells during regeneration.

    PubMed

    Sobkow, Lidia; Epperlein, Hans-Henning; Herklotz, Stephan; Straube, Werner L; Tanaka, Elly M

    2006-02-15

    The development of transgenesis in axolotls is crucial for studying development and regeneration as it would allow for long-term cell fate tracing as well as gene expression analysis. We demonstrate here that plasmid injection into the one-cell stage axolotl embryo generates mosaic transgenic animals that display germline transmission of the transgene. The inclusion of SceI meganuclease in the injections (Thermes, V., Grabher, C., Ristoratore, F., Bourrat, F., Choulika, A., Wittbrodt, J., Joly, J.S., 2002. I-SceI meganuclease mediates highly efficient transgenesis in fish. Mech. Dev. 118, 91-98) resulted in a higher percentage of F0 animals displaying strong expression throughout the body. This represents the first demonstration in the axolotl of germline transmission of a transgene. Using this technique we have generated a germline transgenic animal expressing GFP ubiquitously in all tissues examined. We have used this animal to study cell fate in the dorsal fin during development. We have uncovered a contribution of somite cells to dorsal fin mesenchyme in the axolotl, which was previously assumed to derive solely from neural crest. We have also studied the role of blood during tail regeneration by transplanting the ventral blood-forming region from GFP+ embryos into unlabeled hosts. During tail regeneration, we do not observe GFP+ cells contributing to muscle or nerve, suggesting that during tail regeneration blood stem cells do not undergo significant plasticity. PMID:16387293

  11. Reprogramming of cell fate: epigenetic memory and the erasure of memories past

    PubMed Central

    Nashun, Buhe; Hill, Peter WS; Hajkova, Petra

    2015-01-01

    Cell identity is a reflection of a cell type-specific gene expression profile, and consequently, cell type-specific transcription factor networks are considered to be at the heart of a given cellular phenotype. Although generally stable, cell identity can be reprogrammed in vitro by forced changes to the transcriptional network, the most dramatic example of which was shown by the induction of pluripotency in somatic cells by the ectopic expression of defined transcription factors alone. Although changes to cell fate can be achieved in this way, the efficiency of such conversion remains very low, in large part due to specific chromatin signatures constituting an epigenetic barrier to the transcription factor-mediated reprogramming processes. Here we discuss the two-way relationship between transcription factor binding and chromatin structure during cell fate reprogramming. We additionally explore the potential roles and mechanisms by which histone variants, chromatin remodelling enzymes, and histone and DNA modifications contribute to the stability of cell identity and/or provide a permissive environment for cell fate change during cellular reprogramming. PMID:25820261

  12. Human mammary progenitor cell fate decisions are products of interactions with combinatorial microenvironments

    SciTech Connect

    LaBarge, Mark A; Nelson, Celeste M; Villadsen, Rene; Fridriksdottir, Agla; Ruth, Jason R; Stampfer, Martha R; Petersen, Ole W; Bissell, Mina J

    2008-09-19

    In adult tissues, multi-potent progenitor cells are some of the most primitive members of the developmental hierarchies that maintain homeostasis. That progenitors and their more mature progeny share identical genomes, suggests that fate decisions are directed by interactions with extrinsic soluble factors, ECM, and other cells, as well as physical properties of the ECM. To understand regulation of fate decisions, therefore, would require a means of understanding carefully choreographed combinatorial interactions. Here we used microenvironment protein microarrays to functionally identify combinations of cell-extrinsic mammary gland proteins and ECM molecules that imposed specific cell fates on bipotent human mammary progenitor cells. Micropatterned cell culture surfaces were fabricated to distinguish between the instructive effects of cell-cell versus cell-ECM interactions, as well as constellations of signaling molecules; and these were used in conjunction with physiologically relevant 3 dimensional human breast cultures. Both immortalized and primary human breast progenitors were analyzed. We report on the functional ability of those proteins of the mammary gland that maintain quiescence, maintain the progenitor state, and guide progenitor differentiation towards myoepithelial and luminal lineages.

  13. mTOR Links Environmental Signals to T Cell Fate Decisions

    PubMed Central

    Chapman, Nicole M.; Chi, Hongbo

    2015-01-01

    T cell fate decisions play an integral role in maintaining the health of organisms under homeostatic and inflammatory conditions. The localized microenvironment in which developing and mature T cells reside provides signals that serve essential functions in shaping these fate decisions. These signals are derived from the immune compartment, including antigens, co-stimulation, and cytokines, and other factors, including growth factors and nutrients. The mechanistic target of rapamycin (mTOR), a vital sensor of signals within the immune microenvironment, is a central regulator of T cell biology. In this review, we discuss how various environmental cues tune mTOR activity in T cells, and summarize how mTOR integrates these signals to influence multiple aspects of T cell biology. PMID:25653651

  14. Quantifying intrinsic and extrinsic control of single-cell fates in cancer and stem/progenitor cell pedigrees with competing risks analysis

    PubMed Central

    Cornwell, J. A.; Hallett, R. M.; der Mauer, S. Auf; Motazedian, A.; Schroeder, T.; Draper, J. S.; Harvey, R. P.; Nordon, R. E.

    2016-01-01

    The molecular control of cell fate and behaviour is a central theme in biology. Inherent heterogeneity within cell populations requires that control of cell fate is studied at the single-cell level. Time-lapse imaging and single-cell tracking are powerful technologies for acquiring cell lifetime data, allowing quantification of how cell-intrinsic and extrinsic factors control single-cell fates over time. However, cell lifetime data contain complex features. Competing cell fates, censoring, and the possible inter-dependence of competing fates, currently present challenges to modelling cell lifetime data. Thus far such features are largely ignored, resulting in loss of data and introducing a source of bias. Here we show that competing risks and concordance statistics, previously applied to clinical data and the study of genetic influences on life events in twins, respectively, can be used to quantify intrinsic and extrinsic control of single-cell fates. Using these statistics we demonstrate that 1) breast cancer cell fate after chemotherapy is dependent on p53 genotype; 2) granulocyte macrophage progenitors and their differentiated progeny have concordant fates; and 3) cytokines promote self-renewal of cardiac mesenchymal stem cells by symmetric divisions. Therefore, competing risks and concordance statistics provide a robust and unbiased approach for evaluating hypotheses at the single-cell level. PMID:27250534

  15. Identification and Quantification of Processes Affecting the Fate of Ethanol-Blended Fuel in the Subsurface

    NASA Astrophysics Data System (ADS)

    Devries, J. M.; Mayer, K. U.

    2015-12-01

    At present, the oil and gas industry distributes gasoline with an ethanol content of up to 10% (E10) to the consumer. However, ethanol advocates are promoting gasoline blends with higher ethanol content to be introduced into the market (e.g., E20, corresponding to an ethanol content of 20%). The likelihood of unintended fuel releases with elevated ethanol concentrations through surficial spills or from underground storage systems will therefore increase. A particular concern is the increased rate of CH4 and CO2 production as the spill biodegrades, which is believed to be associated with the increased ethanol content in the fuel. Consequently, high gas generation rates associated with ethanol-blended fuels may amplify the risk of vapor intrusion of CH4 and BTEX into basements or other subsurface structures that may be nearby. A comprehensive and comparative study on the fate of higher concentration ethanol-blended fuels in the subsurface has not been conducted to date. The present study focuses on determining the fate of ethanol blended fuels in the subsurface through a series of controlled and instrumented laboratory column experiments. The experiments compare the behavior of pure gasoline with that of ethanol-blended fuels for different soil types (sand and silt) in columns 2 meters tall and 30cm in diameter. The column experiments focus on the quantification of gas generation by volatilization and biodegradation and 1-D vertical fate and transport of CO2, CH4, benzene and toluene through the vadose zone. The fuel blends have been injected into the lower third of the columns and gas composition and fluxes within the column are being monitored over time. The goal of this study is to contribute to the scientific foundation that will allow gauging the level of risk and the need for remediation at fuel spill sites with higher ethanol blends.

  16. The C. elegans TPR Containing Protein, TRD-1, Regulates Cell Fate Choice in the Developing Germ Line and Epidermis

    PubMed Central

    Hughes, Samantha; Wilkinson, Henry; Gilbert, Sophie P. R.; Kishida, Marcia; Ding, Siyu Serena; Woollard, Alison

    2014-01-01

    Correct cell fate choice is crucial in development. In post-embryonic development of the hermaphroditic Caenorhabitis elegans, distinct cell fates must be adopted in two diverse tissues. In the germline, stem cells adopt one of three possible fates: mitotic cell cycle, or gamete formation via meiosis, producing either sperm or oocytes. In the epidermis, the stem cell-like seam cells divide asymmetrically, with the daughters taking on either a proliferative (seam) or differentiated (hypodermal or neuronal) fate. We have isolated a novel conserved C. elegans tetratricopeptide repeat containing protein, TRD-1, which is essential for cell fate determination in both the germline and the developing epidermis and has homologs in other species, including humans (TTC27). We show that trd-1(RNAi) and mutant animals have fewer seam cells as a result of inappropriate differentiation towards the hypodermal fate. In the germline, trd-1 RNAi results in a strong masculinization phenotype, as well as defects in the mitosis to meiosis switch. Our data suggests that trd-1 acts downstream of tra-2 but upstream of fem-3 in the germline sex determination pathway, and exhibits a constellation of phenotypes in common with other Mog (masculinization of germline) mutants. Thus, trd-1 is a new player in both the somatic and germline cell fate determination machinery, suggestive of a novel molecular connection between the development of these two diverse tissues. PMID:25493563

  17. Transcriptional control of stem cell fate by E2Fs and pocket proteins

    PubMed Central

    Julian, Lisa M.; Blais, Alexandre

    2015-01-01

    E2F transcription factors and their regulatory partners, the pocket proteins (PPs), have emerged as essential regulators of stem cell fate control in a number of lineages. In mammals, this role extends from both pluripotent stem cells to those encompassing all embryonic germ layers, as well as extra-embryonic lineages. E2F/PP-mediated regulation of stem cell decisions is highly evolutionarily conserved, and is likely a pivotal biological mechanism underlying stem cell homeostasis. This has immense implications for organismal development, tissue maintenance, and regeneration. In this article, we discuss the roles of E2F factors and PPs in stem cell populations, focusing on mammalian systems. We discuss emerging findings that position the E2F and PP families as widespread and dynamic epigenetic regulators of cell fate decisions. Additionally, we focus on the ever expanding landscape of E2F/PP target genes, and explore the possibility that E2Fs are not simply regulators of general ‘multi-purpose’ cell fate genes but can execute tissue- and cell type-specific gene regulatory programs. PMID:25972892

  18. Mitochondrial Dynamics Controls T Cell Fate through Metabolic Programming.

    PubMed

    Buck, Michael D; O'Sullivan, David; Klein Geltink, Ramon I; Curtis, Jonathan D; Chang, Chih-Hao; Sanin, David E; Qiu, Jing; Kretz, Oliver; Braas, Daniel; van der Windt, Gerritje J W; Chen, Qiongyu; Huang, Stanley Ching-Cheng; O'Neill, Christina M; Edelson, Brian T; Pearce, Edward J; Sesaki, Hiromi; Huber, Tobias B; Rambold, Angelika S; Pearce, Erika L

    2016-06-30

    Activated effector T (TE) cells augment anabolic pathways of metabolism, such as aerobic glycolysis, while memory T (TM) cells engage catabolic pathways, like fatty acid oxidation (FAO). However, signals that drive these differences remain unclear. Mitochondria are metabolic organelles that actively transform their ultrastructure. Therefore, we questioned whether mitochondrial dynamics controls T cell metabolism. We show that TE cells have punctate mitochondria, while TM cells maintain fused networks. The fusion protein Opa1 is required for TM, but not TE cells after infection, and enforcing fusion in TE cells imposes TM cell characteristics and enhances antitumor function. Our data suggest that, by altering cristae morphology, fusion in TM cells configures electron transport chain (ETC) complex associations favoring oxidative phosphorylation (OXPHOS) and FAO, while fission in TE cells leads to cristae expansion, reducing ETC efficiency and promoting aerobic glycolysis. Thus, mitochondrial remodeling is a signaling mechanism that instructs T cell metabolic programming.

  19. Mitochondrial Dynamics Controls T Cell Fate through Metabolic Programming.

    PubMed

    Buck, Michael D; O'Sullivan, David; Klein Geltink, Ramon I; Curtis, Jonathan D; Chang, Chih-Hao; Sanin, David E; Qiu, Jing; Kretz, Oliver; Braas, Daniel; van der Windt, Gerritje J W; Chen, Qiongyu; Huang, Stanley Ching-Cheng; O'Neill, Christina M; Edelson, Brian T; Pearce, Edward J; Sesaki, Hiromi; Huber, Tobias B; Rambold, Angelika S; Pearce, Erika L

    2016-06-30

    Activated effector T (TE) cells augment anabolic pathways of metabolism, such as aerobic glycolysis, while memory T (TM) cells engage catabolic pathways, like fatty acid oxidation (FAO). However, signals that drive these differences remain unclear. Mitochondria are metabolic organelles that actively transform their ultrastructure. Therefore, we questioned whether mitochondrial dynamics controls T cell metabolism. We show that TE cells have punctate mitochondria, while TM cells maintain fused networks. The fusion protein Opa1 is required for TM, but not TE cells after infection, and enforcing fusion in TE cells imposes TM cell characteristics and enhances antitumor function. Our data suggest that, by altering cristae morphology, fusion in TM cells configures electron transport chain (ETC) complex associations favoring oxidative phosphorylation (OXPHOS) and FAO, while fission in TE cells leads to cristae expansion, reducing ETC efficiency and promoting aerobic glycolysis. Thus, mitochondrial remodeling is a signaling mechanism that instructs T cell metabolic programming. PMID:27293185

  20. Transcriptional regulation of effector and memory CD8+ T cell fates

    PubMed Central

    Thaventhiran, James E. D.; Fearon, Douglas T.; Gattinoni, Luca

    2013-01-01

    Immunity to intracellular pathogens and cancer relies on the generation of robust CD8+ T cell effector responses as well as the establishment of immunological memory. During a primary immune response CD8+ T cells experience diverse extracellular environmental cues and cell-cell interactions that trigger downstream transcriptional programs ultimately guiding a CD8+ T cell to undertake either an effector or a memory cell fate. Here, we discuss our current understanding of the signaling pathways and transcriptional networks that regulate effector and memory commitment in CD8+ T lymphocytes. PMID:23747000

  1. Cell contractility arising from topography and shear flow determines human mesenchymal stem cell fate

    PubMed Central

    Sonam, Surabhi; Sathe, Sharvari R.; Yim, Evelyn K.F.; Sheetz, Michael P.; Lim, Chwee Teck

    2016-01-01

    Extracellular matrix (ECM) of the human Mesenchymal Stem Cells (MSCs) influences intracellular tension and is known to regulate stem cell fate. However, little is known about the physiological conditions in the bone marrow, where external forces such as fluid shear stress, apart from the physical characteristics of the ECM, influence stem cell response. Here, we hypothesize that substrate topography and fluid shear stress alter the cellular contractile forces, influence the genetic expression of the stem cells and hence alter their lineage. When fluid shear stress was applied, human MSCs with higher contractility (seeded on 1 μm wells) underwent osteogenesis, whereas those with lower contractility (seeded on 2 μm gratings) remained multipotent. Compared to human MSCs seeded on gratings, those seeded on wells exhibited altered alignment and an increase in the area and number of focal adhesions. When actomyosin contractility was inhibited, human MSCs did not exhibit differentiation, regardless of the topographical feature they were being cultured on. We conclude that the stresses generated by the applied fluid flow impinge on cell contractility to drive the stem cell differentiation via the contractility of the stem cells. PMID:26879739

  2. TOO MANY MOUTHS promotes cell fate progression in stomatal development of Arabidopsis stems.

    PubMed

    Bhave, Neela S; Veley, Kira M; Nadeau, Jeanette A; Lucas, Jessica R; Bhave, Sanjay L; Sack, Fred D

    2009-01-01

    Mutations in TOO MANY MOUTHS (TMM), which encodes a receptor-like protein, cause stomatal patterning defects in Arabidopsis leaves but eliminate stomatal formation in stems. Stomatal development in wild-type and tmm stems was analyzed to define TMM function. Epidermal cells in young tmm stems underwent many asymmetric divisions characteristic of entry into the stomatal pathway. The resulting precursor cells, meristemoids, appropriately expressed cell fate markers such as pTMM:GFP. However, instead of progressing developmentally by forming a guard mother cell, the meristemoids arrested, dedifferentiated, and enlarged. Thus asymmetric divisions are necessary but not sufficient for stomatal formation in stems, and TMM promotes the fate and developmental progression of early precursor cells. Comparable developmental and mature stomatal phenotypes were also found in tmm hypocotyls and in the proximal flower stalk. TMM is also a positive regulator of meristemoid division in leaves suggesting that TMM generally promotes meristemoid activity. Our results are consistent with a model in which TMM interacts with other proteins to modulate precursor cell fate and progression in an organ and domain-specific manner. Finally, the consistent presence of a small number of dedifferentiated meristemoids in mature wild-type stems suggests that precursor cell arrest is a normal feature of Arabidopsis stem development.

  3. Stem-cell dynamics and lineage topology from in vivo fate mapping in the hematopoietic system.

    PubMed

    Höfer, Thomas; Barile, Melania; Flossdorf, Michael

    2016-06-01

    In recent years, sophisticated fate-mapping tools have been developed to study the behavior of stem cells in the intact organism. These experimental approaches are beginning to yield a quantitative picture of how cell numbers are regulated during steady state and in response to challenges. Focusing on hematopoiesis and immune responses, we discuss how novel mathematical approaches driven by these fate-mapping data have provided insights into the dynamics and topology of cellular differentiation pathways in vivo. The combination of experiment and theory has allowed to quantify the degree of self-renewal in stem and progenitor cells, shown how native hematopoiesis differs fundamentally from post-transplantation hematopoiesis, and uncovered that the diversification of T lymphocytes during immune responses resembles tissue renewal driven by stem cells. PMID:27107166

  4. Multidimensional nanomaterials for the control of stem cell fate

    NASA Astrophysics Data System (ADS)

    Chueng, Sy-Tsong Dean; Yang, Letao; Zhang, Yixiao; Lee, Ki-Bum

    2016-09-01

    Current stem cell therapy suffers low efficiency in giving rise to differentiated cell lineages, which can replace the original damaged cells. Nanomaterials, on the other hand, provide unique physical size, surface chemistry, conductivity, and topographical microenvironment to regulate stem cell differentiation through multidimensional approaches to facilitate gene delivery, cell-cell, and cell-ECM interactions. In this review, nanomaterials are demonstrated to work both alone and synergistically to guide selective stem cell differentiation. From three different nanotechnology families, three approaches are shown: (1) soluble microenvironmental factors; (2) insoluble physical microenvironment; and (3) nano-topographical features. As regenerative medicine is heavily invested in effective stem cell therapy, this review is inspired to generate discussions in the potential clinical applications of multi-dimensional nanomaterials.

  5. Developmental biology: cell fate in the mammary gland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most breast cancers have their origin in the luminal epithelial cells of the mammary gland. Defining how a master regulator controls the development of this cell lineage could provide important hints about why this should be. ...

  6. Bioengineering tools to elucidate and control the fate of transplanted stem cells.

    PubMed

    Sridharan, Rukmani; Karp, Jeffrey M; Zhao, Weian

    2014-06-01

    For the last decade, stem cell therapies have demonstrated enormous potential for solving some of the most tragic illnesses, diseases and tissue defects worldwide. Currently, more than 1300 clinical trials use stem cell therapy to solve a spectrum of cardiovascular, neurodegenerative and autoimmune diseases (http://www.clinicaltrials.gov, Jan 2014, search term: stem cell therapy; only currently recruiting and completed studies are included in the search). However, the efficacy of stem cell transplantation in patients has not been well established, and recent clinical trials have produced mixed results. We attribute this lack of efficacy in part to an incomplete understanding of the fate of stem cells following transplantation and the lack of control over cell fate, especially cell-homing and therapeutic functions. In the present review, we present two of our recently developed technologies that aim to address the above-mentioned bottlenecks in stem cell therapy specifically in the areas of MSCs (mesenchymal stem cells): (i) aptamer-based cell-surface sensors to study cellular microenvironments, and (ii) mRNA engineering technology to enhance the homing and immunomodulatory efficacy of transplanted stem cells. The first engineering strategy aims to elucidate the basic cellular signalling that occurs in the microenvironment of transplanted stem cells in real time. The second technique involves a simple mRNA transfection that improves the homing and anti-inflammatory capability of MSCs. Although we have specifically applied these engineering techniques to MSCs, these strategies can be incorporated for almost any cell type to determine and control the fate of transplanted stem cells.

  7. Repression of somatic cell fate in the germline.

    PubMed

    Robert, Valérie J; Garvis, Steve; Palladino, Francesca

    2015-10-01

    Germ cells must transmit genetic information across generations, and produce gametes while also maintaining the potential to form all cell types after fertilization. Preventing the activation of somatic programs is, therefore, crucial to the maintenance of germ cell identity. Studies in Caenorhabditis elegans, Drosophila melanogaster, and mouse have revealed both similarities and differences in how somatic gene expression is repressed in germ cells, thereby preventing their conversion into somatic tissues. This review will focus on recent developments in our understanding of how global or gene-specific transcriptional repression, chromatin regulation, and translational repression operate in the germline to maintain germ cell identity and repress somatic differentiation programs. PMID:26043973

  8. Planar cell polarity effector gene Intu regulates cell fate-specific differentiation of keratinocytes through the primary cilia.

    PubMed

    Dai, D; Li, L; Huebner, A; Zeng, H; Guevara, E; Claypool, D J; Liu, A; Chen, J

    2013-01-01

    Genes involved in the planar cell polarity (PCP) signaling pathway are essential for a number of developmental processes in mammals, such as convergent extension and ciliogenesis. Tissue-specific PCP effector genes of the PCP signaling pathway are believed to mediate PCP signals in a tissue- and cell type-specific manner. However, how PCP signaling controls the morphogenesis of mammalian tissues remains unclear. In this study, we investigated the role of inturned (Intu), a tissue-specific PCP effector gene, during hair follicle formation in mice. Tissue-specific disruption of Intu in embryonic epidermis resulted in hair follicle morphogenesis arrest because of the failure of follicular keratinocyte to differentiate. Targeting Intu in the epidermis resulted in almost complete loss of primary cilia in epidermal and follicular keratinocytes, and a suppressed hedgehog signaling pathway. Surprisingly, the epidermal stratification and differentiation programs and barrier function were not affected. These results demonstrate that tissue-specific PCP effector genes of the PCP signaling pathway control the differentiation of keratinocytes through the primary cilia in a cell fate- and context-dependent manner, which may be critical in orchestrating the propagation and interpretation of polarity signals established by the core PCP components. PMID:22935613

  9. Planar cell polarity effector gene Intu regulates cell fate-specific differentiation of keratinocytes through the primary cilia.

    PubMed

    Dai, D; Li, L; Huebner, A; Zeng, H; Guevara, E; Claypool, D J; Liu, A; Chen, J

    2013-01-01

    Genes involved in the planar cell polarity (PCP) signaling pathway are essential for a number of developmental processes in mammals, such as convergent extension and ciliogenesis. Tissue-specific PCP effector genes of the PCP signaling pathway are believed to mediate PCP signals in a tissue- and cell type-specific manner. However, how PCP signaling controls the morphogenesis of mammalian tissues remains unclear. In this study, we investigated the role of inturned (Intu), a tissue-specific PCP effector gene, during hair follicle formation in mice. Tissue-specific disruption of Intu in embryonic epidermis resulted in hair follicle morphogenesis arrest because of the failure of follicular keratinocyte to differentiate. Targeting Intu in the epidermis resulted in almost complete loss of primary cilia in epidermal and follicular keratinocytes, and a suppressed hedgehog signaling pathway. Surprisingly, the epidermal stratification and differentiation programs and barrier function were not affected. These results demonstrate that tissue-specific PCP effector genes of the PCP signaling pathway control the differentiation of keratinocytes through the primary cilia in a cell fate- and context-dependent manner, which may be critical in orchestrating the propagation and interpretation of polarity signals established by the core PCP components.

  10. The Paired-box protein PAX-3 regulates the choice between lateral and ventral epidermal cell fates in C. elegans.

    PubMed

    Thompson, Kenneth W; Joshi, Pradeep; Dymond, Jessica S; Gorrepati, Lakshmi; Smith, Harold E; Krause, Michael W; Eisenmann, David M

    2016-04-15

    The development of the single cell layer skin or hypodermis of Caenorhabditis elegans is an excellent model for understanding cell fate specification and differentiation. Early in C. elegans embryogenesis, six rows of hypodermal cells adopt dorsal, lateral or ventral fates that go on to display distinct behaviors during larval life. Several transcription factors are known that function in specifying these major hypodermal cell fates, but our knowledge of the specification of these cell types is sparse, particularly in the case of the ventral hypodermal cells, which become Vulval Precursor Cells and form the vulval opening in response to extracellular signals. Previously, the gene pvl-4 was identified in a screen for mutants with defects in vulval development. We found by whole genome sequencing that pvl-4 is the Paired-box gene pax-3, which encodes the sole PAX-3 transcription factor homolog in C. elegans. pax-3 mutants show embryonic and larval lethality, and body morphology abnormalities indicative of hypodermal cell defects. We report that pax-3 is expressed in ventral P cells and their descendants during embryogenesis and early larval stages, and that in pax-3 reduction-of-function animals the ventral P cells undergo a cell fate transformation and express several markers of the lateral seam cell fate. Furthermore, forced expression of pax-3 in the lateral hypodermal cells causes them to lose expression of seam cell markers. We propose that pax-3 functions in the ventral hypodermal cells to prevent these cells from adopting the lateral seam cell fate. pax-3 represents the first gene required for specification solely of the ventral hypodermal fate in C. elegans providing insights into cell type diversification. PMID:26953187

  11. FGF/MAPK signaling sets the switching threshold of a bistable circuit controlling cell fate decisions in embryonic stem cells.

    PubMed

    Schröter, Christian; Rué, Pau; Mackenzie, Jonathan Peter; Martinez Arias, Alfonso

    2015-12-15

    Intracellular transcriptional regulators and extracellular signaling pathways together regulate the allocation of cell fates during development, but how their molecular activities are integrated to establish the correct proportions of cells with particular fates is not known. Here we study this question in the context of the decision between the epiblast (Epi) and the primitive endoderm (PrE) fate that occurs in the mammalian preimplantation embryo. Using an embryonic stem cell (ESC) model, we discover two successive functions of FGF/MAPK signaling in this decision. First, the pathway needs to be inhibited to make the PrE-like gene expression program accessible for activation by GATA transcription factors in ESCs. In a second step, MAPK signaling levels determine the threshold concentration of GATA factors required for PrE-like differentiation, and thereby control the proportion of cells differentiating along this lineage. Our findings can be explained by a simple mutual repression circuit modulated by FGF/MAPK signaling. This might be a general network architecture to integrate the activity of signal transduction pathways and transcriptional regulators, and serve to balance proportions of cell fates in several contexts.

  12. Memory and modularity in cell-fate decision making

    NASA Astrophysics Data System (ADS)

    Norman, Thomas M.; Lord, Nathan D.; Paulsson, Johan; Losick, Richard

    2013-11-01

    Genetically identical cells sharing an environment can display markedly different phenotypes. It is often unclear how much of this variation derives from chance, external signals, or attempts by individual cells to exert autonomous phenotypic programs. By observing thousands of cells for hundreds of consecutive generations under constant conditions, we dissect the stochastic decision between a solitary, motile state and a chained, sessile state in Bacillus subtilis. We show that the motile state is `memoryless', exhibiting no autonomous control over the time spent in the state. In contrast, the time spent as connected chains of cells is tightly controlled, enforcing coordination among related cells in the multicellular state. We show that the three-protein regulatory circuit governing the decision is modular, as initiation and maintenance of chaining are genetically separable functions. As stimulation of the same initiating pathway triggers biofilm formation, we argue that autonomous timing allows a trial commitment to multicellularity that external signals could extend.

  13. The Sox Family of Transcription Factors: Versatile Regulators of Stem and Progenitor Cell Fate

    PubMed Central

    Sarkar, Abby; Hochedlinger, Konrad

    2013-01-01

    The Sox family of transcription factors are well-established regulators of cell fate decisions during development. Accumulating evidence documents that they play additional roles in adult tissue homeostasis and regeneration. Remarkably, forced expression of Sox factors, in combination with other synergistic factors, reprograms differentiated cells into somatic or pluripotent stem cells. Dysregulation of Sox factors has been further implicated in diseases including cancer. Here, we review molecular and functional evidence linking Sox proteins with stem cell biology, cellular reprogramming, and disease with an emphasis on Sox2. PMID:23290134

  14. Regulation of epidermal cell fate in Arabidopsis roots: the importance of multiple feedback loops

    PubMed Central

    Schiefelbein, John; Huang, Ling; Zheng, Xiaohua

    2014-01-01

    The specification of distinct cell types in multicellular organisms is accomplished via establishment of differential gene expression. A major question is the nature of the mechanisms that establish this differential expression in time and space. In plants, the formation of the hair and non-hair cell types in the root epidermis has been used as a model to understand regulation of cell specification. Recent findings show surprising complexity in the number and the types of regulatory interactions between the multiple transcription factor genes/proteins influencing root epidermis cell fate. Here, we describe this regulatory network and the importance of the multiple feedback loops for its establishment and maintenance. PMID:24596575

  15. Cap-independent translation by DAP5 controls cell fate decisions in human embryonic stem cells.

    PubMed

    Yoffe, Yael; David, Maya; Kalaora, Rinat; Povodovski, Lital; Friedlander, Gilgi; Feldmesser, Ester; Ainbinder, Elena; Saada, Ann; Bialik, Shani; Kimchi, Adi

    2016-09-01

    Multiple transcriptional and epigenetic changes drive differentiation of embryonic stem cells (ESCs). This study unveils an additional level of gene expression regulation involving noncanonical, cap-independent translation of a select group of mRNAs. This is driven by death-associated protein 5 (DAP5/eIF4G2/NAT1), a translation initiation factor mediating IRES-dependent translation. We found that the DAP5 knockdown from human ESCs (hESCs) resulted in persistence of pluripotent gene expression, delayed induction of differentiation-associated genes in different cell lineages, and defective embryoid body formation. The latter involved improper cellular organization, lack of cavitation, and enhanced mislocalized apoptosis. RNA sequencing of polysome-associated mRNAs identified candidates with reduced translation efficiency in DAP5-depleted hESCs. These were enriched in mitochondrial proteins involved in oxidative respiration, a pathway essential for differentiation, the significance of which was confirmed by the aberrant mitochondrial morphology and decreased oxidative respiratory activity in DAP5 knockdown cells. Further analysis identified the chromatin modifier HMGN3 as a cap-independent DAP5 translation target whose knockdown resulted in defective differentiation. Thus, DAP5-mediated translation of a specific set of proteins is critical for the transition from pluripotency to differentiation, highlighting the importance of cap-independent translation in stem cell fate decisions.

  16. Cap-independent translation by DAP5 controls cell fate decisions in human embryonic stem cells.

    PubMed

    Yoffe, Yael; David, Maya; Kalaora, Rinat; Povodovski, Lital; Friedlander, Gilgi; Feldmesser, Ester; Ainbinder, Elena; Saada, Ann; Bialik, Shani; Kimchi, Adi

    2016-09-01

    Multiple transcriptional and epigenetic changes drive differentiation of embryonic stem cells (ESCs). This study unveils an additional level of gene expression regulation involving noncanonical, cap-independent translation of a select group of mRNAs. This is driven by death-associated protein 5 (DAP5/eIF4G2/NAT1), a translation initiation factor mediating IRES-dependent translation. We found that the DAP5 knockdown from human ESCs (hESCs) resulted in persistence of pluripotent gene expression, delayed induction of differentiation-associated genes in different cell lineages, and defective embryoid body formation. The latter involved improper cellular organization, lack of cavitation, and enhanced mislocalized apoptosis. RNA sequencing of polysome-associated mRNAs identified candidates with reduced translation efficiency in DAP5-depleted hESCs. These were enriched in mitochondrial proteins involved in oxidative respiration, a pathway essential for differentiation, the significance of which was confirmed by the aberrant mitochondrial morphology and decreased oxidative respiratory activity in DAP5 knockdown cells. Further analysis identified the chromatin modifier HMGN3 as a cap-independent DAP5 translation target whose knockdown resulted in defective differentiation. Thus, DAP5-mediated translation of a specific set of proteins is critical for the transition from pluripotency to differentiation, highlighting the importance of cap-independent translation in stem cell fate decisions. PMID:27664238

  17. Ductular reaction-on-a-chip: Microfluidic co-cultures to study stem cell fate selection during liver injury

    PubMed Central

    Haque, Amranul; Gheibi, Pantea; Stybayeva, Gulnaz; Gao, Yandong; Torok, Natalie; Revzin, Alexander

    2016-01-01

    Liver injury modulates local microenvironment, triggering production of signals that instruct stem cell fate choices. In this study, we employed a microfluidic co-culture system to recreate important interactions in the liver stem cell niche, those between adult hepatocytes and liver progenitor cells (LPCs). We demonstrate that pluripotent stem cell-derived LPCs choose hepatic fate when cultured next to healthy hepatocytes but begin biliary differentiation program when co-cultured with injured hepatocytes. We connect this fate selection to skewing in production of hepatocyte growth factor (HGF) and transforming growth factor (TGF)-β1 caused by injury. Significantly, biliary fate selection of LPCs was not observed in the absence of hepatocytes nor did it happen in the presence of TGF-β inhibitors. Our study demonstrates that microfluidic culture systems may offer an interesting new tool for dissecting cellular interactions leading to aberrant stem cell differentiation during injury. PMID:27796316

  18. Long noncoding RNAs in cell-fate programming and reprogramming.

    PubMed

    Flynn, Ryan A; Chang, Howard Y

    2014-06-01

    In recent years, long noncoding RNAs (lncRNAs) have emerged as an important class of regulators of gene expression. lncRNAs exhibit several distinctive features that confer unique regulatory functions, including exquisite cell- and tissue-specific expression and the capacity to transduce higher-order spatial information. Here we review evidence showing that lncRNAs exert critical functions in adult tissue stem cells, including skin, brain, and muscle, as well as in developmental patterning and pluripotency. We highlight new approaches for ascribing lncRNA functions and discuss mammalian dosage compensation as a classic example of an lncRNA network coupled to stem cell differentiation.

  19. Concentration Sensing by the Moving Nucleus in Cell Fate Determination: A Computational Analysis.

    PubMed

    Aggarwal, Varun; Dickinson, Richard B; Lele, Tanmay P

    2016-01-01

    During development of the vertebrate neuroepithelium, the nucleus in neural progenitor cells (NPCs) moves from the apex toward the base and returns to the apex (called interkinetic nuclear migration) at which point the cell divides. The fate of the resulting daughter cells is thought to depend on the sampling by the moving nucleus of a spatial concentration profile of the cytoplasmic Notch intracellular domain (NICD). However, the nucleus executes complex stochastic motions including random waiting and back and forth motions, which can expose the nucleus to randomly varying levels of cytoplasmic NICD. How nuclear position can determine daughter cell fate despite the stochastic nature of nuclear migration is not clear. Here we derived a mathematical model for reaction, diffusion, and nuclear accumulation of NICD in NPCs during interkinetic nuclear migration (INM). Using experimentally measured trajectory-dependent probabilities of nuclear turning, nuclear waiting times and average nuclear speeds in NPCs in the developing zebrafish retina, we performed stochastic simulations to compute the nuclear trajectory-dependent probabilities of NPC differentiation. Comparison with experimentally measured nuclear NICD concentrations and trajectory-dependent probabilities of differentiation allowed estimation of the NICD cytoplasmic gradient. Spatially polarized production of NICD, rapid NICD cytoplasmic consumption and the time-averaging effect of nuclear import/export kinetics are sufficient to explain the experimentally observed differentiation probabilities. Our computational studies lend quantitative support to the feasibility of the nuclear concentration-sensing mechanism for NPC fate determination in zebrafish retina.

  20. Neural crest and somitic mesoderm as paradigms to investigate cell fate decisions during development.

    PubMed

    Nitzan, Erez; Kalcheim, Chaya

    2013-01-01

    The dorsal domains of the neural tube and somites are transient embryonic epithelia; they constitute the source of neural crest progenitors that generate the peripheral nervous system, pigment cells and ectomesenchyme, and of the dermomyotome that develops into myocytes, dermis and vascular cells, respectively. Based on the variety of derivatives produced by each type of epithelium, a classical yet still highly relevant question is whether these embryonic epithelia are composed of homogeneous multipotent progenitors or, alternatively, of subsets of fate-restricted cells. Growing evidence substantiates the notion that both the dorsal tube and the dermomyotome are heterogeneous epithelia composed of multipotent as well as fate-restricted precursors that emerge as such in a spatio-temporally regulated manner. Elucidation of the state of commitment of the precedent progenitors is of utmost significance for deciphering the mechanisms that regulate fate segregation during embryogenesis. In addition, it will contribute to understanding the nature of well documented neural crest-somite interactions shown to modulate the timing of neural crest cell emigration, their segmental migration, and myogenesis.

  1. Concentration Sensing by the Moving Nucleus in Cell Fate Determination: A Computational Analysis.

    PubMed

    Aggarwal, Varun; Dickinson, Richard B; Lele, Tanmay P

    2016-01-01

    During development of the vertebrate neuroepithelium, the nucleus in neural progenitor cells (NPCs) moves from the apex toward the base and returns to the apex (called interkinetic nuclear migration) at which point the cell divides. The fate of the resulting daughter cells is thought to depend on the sampling by the moving nucleus of a spatial concentration profile of the cytoplasmic Notch intracellular domain (NICD). However, the nucleus executes complex stochastic motions including random waiting and back and forth motions, which can expose the nucleus to randomly varying levels of cytoplasmic NICD. How nuclear position can determine daughter cell fate despite the stochastic nature of nuclear migration is not clear. Here we derived a mathematical model for reaction, diffusion, and nuclear accumulation of NICD in NPCs during interkinetic nuclear migration (INM). Using experimentally measured trajectory-dependent probabilities of nuclear turning, nuclear waiting times and average nuclear speeds in NPCs in the developing zebrafish retina, we performed stochastic simulations to compute the nuclear trajectory-dependent probabilities of NPC differentiation. Comparison with experimentally measured nuclear NICD concentrations and trajectory-dependent probabilities of differentiation allowed estimation of the NICD cytoplasmic gradient. Spatially polarized production of NICD, rapid NICD cytoplasmic consumption and the time-averaging effect of nuclear import/export kinetics are sufficient to explain the experimentally observed differentiation probabilities. Our computational studies lend quantitative support to the feasibility of the nuclear concentration-sensing mechanism for NPC fate determination in zebrafish retina. PMID:26872214

  2. Programming cell fate on bio-functionalized silicon.

    PubMed

    Premnath, Priyatha; Tan, Bo; Venkatakrishnan, Krishnan

    2015-04-01

    Controlling the growth of cells on the surface of silicon without an additive layer or topographical modification is unexplored. This research article delineates the discovery of unique properties of a bio-functionalized silicon substrate, programmed to repel or control cells, generated by ultrafast femtosecond pulse interaction with silicon. Remarkably, bio-functionalization in any shape or size without change in topology or morphology is observed indicating only sub-surface phase transformations. Material characterization reveals the presence of a unique mixture of phases of SiO2 and Si. Consequently, these variations in phase alter the physicochemical characteristics on the surface of silicon resulting in its bio-functionalization. The culture of mouse embryonic fibroblasts shows unique adhesion characteristics on these bio-functionalized silicon surfaces that include cell controlling, cell trapping, and cell shaping. Furthermore, the directionality of fibroblasts is restrained parallel to bio-functionalized zones as evidenced by changes in cytoskeleton. The controlling of proliferation, migration and adhesion of cells is attributed to unique phase bio-functionalization. This method presents considerable promise in a myriad of applications such as tissue engineering, MEMS, and lab-on-a-chip devices.

  3. ERK2 mediates metabolic stress response to regulate cell fate

    PubMed Central

    Shin, Sejeong; Buel, Gwen R.; Wolgamott, Laura; Plas, David R.; Asara, John M.; Blenis, John; Yoon, Sang-Oh

    2015-01-01

    Insufficient nutrients disrupt physiological homeostasis resulting in diseases and even death. Considering the physiological and pathological consequences of this metabolic stress, the adaptive responses that cells utilize under this condition are of great interest. We show that under low glucose conditions, cells initiate adaptation followed by apoptosis responses using PERK/Akt and MEK1/ERK2 signaling, respectively. For adaptation, cells engage the endoplasmic reticulum stress-induced unfolded protein response, which results in PERK/Akt activation and cell survival. Sustained and extreme energetic stress promotes a switch to isoform-specific MEK1/ERK2 signaling, induction of GCN2/eIF2α phosphorylation and ATF4 expression, which overrides PERK/Akt-mediated adaptation and induces apoptosis through ATF4-dependent expression of pro-apoptotic factors including Bid and Trb3. ERK2 activation during metabolic stress contributes to changes in TCA cycle and amino acid metabolism, and cell death, which is suppressed by glutamate and α-ketoglutarate supplementation. Taken together, our results reveal promising targets to protect cells or tissues from metabolic stress. PMID:26190261

  4. Programming cell fate on bio-functionalized silicon.

    PubMed

    Premnath, Priyatha; Tan, Bo; Venkatakrishnan, Krishnan

    2015-04-01

    Controlling the growth of cells on the surface of silicon without an additive layer or topographical modification is unexplored. This research article delineates the discovery of unique properties of a bio-functionalized silicon substrate, programmed to repel or control cells, generated by ultrafast femtosecond pulse interaction with silicon. Remarkably, bio-functionalization in any shape or size without change in topology or morphology is observed indicating only sub-surface phase transformations. Material characterization reveals the presence of a unique mixture of phases of SiO2 and Si. Consequently, these variations in phase alter the physicochemical characteristics on the surface of silicon resulting in its bio-functionalization. The culture of mouse embryonic fibroblasts shows unique adhesion characteristics on these bio-functionalized silicon surfaces that include cell controlling, cell trapping, and cell shaping. Furthermore, the directionality of fibroblasts is restrained parallel to bio-functionalized zones as evidenced by changes in cytoskeleton. The controlling of proliferation, migration and adhesion of cells is attributed to unique phase bio-functionalization. This method presents considerable promise in a myriad of applications such as tissue engineering, MEMS, and lab-on-a-chip devices. PMID:25731099

  5. Mitochondrial function provides instructive signals for activation-induced B-cell fates.

    PubMed

    Jang, Kyoung-Jin; Mano, Hiroto; Aoki, Koji; Hayashi, Tatsunari; Muto, Akihiko; Nambu, Yukiko; Takahashi, Katsu; Itoh, Katsuhiko; Taketani, Shigeru; Nutt, Stephen L; Igarashi, Kazuhiko; Shimizu, Akira; Sugai, Manabu

    2015-04-10

    During immune reactions, functionally distinct B-cell subsets are generated by stochastic processes, including class-switch recombination (CSR) and plasma cell differentiation (PCD). In this study, we show a strong association between individual B-cell fates and mitochondrial functions. CSR occurs specifically in activated B cells with increased mitochondrial mass and membrane potential, which augment mitochondrial reactive oxygen species (mROS), whereas PCD occurs in cells with decreased mitochondrial mass and potential. These events are consequences of initial slight changes in mROS in mitochondria(high) B-cell populations. In CSR-committed cells, mROS attenuates haeme synthesis by inhibiting ferrous ion addition to protoporphyrin IX, thereby maintaining Bach2 function. Reduced mROS then promotes PCD by increasing haeme synthesis. In PCD-committed cells, Blimp1 reduces mitochondrial mass, thereby reducing mROS levels. Identifying mROS as a haeme synthesis regulator increases the understanding of mechanisms regulating haeme homeostasis and cell fate determination after B-cell activation.

  6. Ultradian oscillations and pulses: coordinating cellular responses and cell fate decisions

    PubMed Central

    Isomura, Akihiro; Kageyama, Ryoichiro

    2014-01-01

    Biological clocks play key roles in organismal development, homeostasis and function. In recent years, much work has focused on circadian clocks, but emerging studies have highlighted the existence of ultradian oscillators – those with a much shorter periodicity than 24 h. Accumulating evidence, together with recently developed optogenetic approaches, suggests that such ultradian oscillators play important roles during cell fate decisions, and analyzing the functional links between ultradian oscillation and cell fate determination will contribute to a deeper understanding of the design principle of developing embryos. In this Review, we discuss the mechanisms of ultradian oscillatory dynamics and introduce examples of ultradian oscillators in various biological contexts. We also discuss how optogenetic technology has been used to elucidate the biological significance of ultradian oscillations. PMID:25249457

  7. Role of bioinspired polymers in determination of pluripotent stem cell fate

    PubMed Central

    Abraham, Sheena; Eroshenko, Nikolai; Rao, Raj R

    2009-01-01

    Human pluripotent stem cells, including embryonic and induced pluripotent stem cells, hold enormous potential for the treatment of many diseases, owing to their ability to generate cell types useful for therapeutic applications. Currently, many stem cell culture propagation and differentiation systems incorporate animal-derived components for promoting self-renewal and differentiation. However, use of these components is labor intensive, carries the risk of xenogeneic contamination and yields compromised experimental results that are difficult to duplicate. From a biomaterials perspective, the generation of an animal- and cell-free biomimetic microenvironment that provides the appropriate physical and chemical cues for stem cell self-renewal or differentiation into specialized cell types would be ideal. This review presents the use of natural and synthetic polymers that support propagation and differentiation of stem cells, in an attempt to obtain a clear understanding of the factors responsible for the determination of stem cell fate. PMID:19580405

  8. microRNAs: key triggers of neuronal cell fate

    PubMed Central

    Meza-Sosa, Karla F.; Pedraza-Alva, Gustavo; Pérez-Martínez, Leonor

    2014-01-01

    Development of the central nervous system (CNS) requires a precisely coordinated series of events. During embryonic development, different intra- and extracellular signals stimulate neural stem cells to become neural progenitors, which eventually irreversibly exit from the cell cycle to begin the first stage of neurogenesis. However, before this event occurs, the self-renewal and proliferative capacities of neural stem cells and neural progenitors must be tightly regulated. Accordingly, the participation of various evolutionary conserved microRNAs is key in distinct central nervous system (CNS) developmental processes of many organisms including human, mouse, chicken, frog, and zebrafish. microRNAs specifically recognize and regulate the expression of target mRNAs by sequence complementarity within the mRNAs 3′ untranslated region and importantly, a single microRNA can have several target mRNAs to regulate a process; likewise, a unique mRNA can be targeted by more than one microRNA. Thus, by regulating different target genes, microRNAs let-7, microRNA-124, and microRNA-9 have been shown to promote the differentiation of neural stem cells and neural progenitors into specific neural cell types while microRNA-134, microRNA-25 and microRNA-137 have been characterized as microRNAs that induce the proliferation of neural stem cells and neural progenitors. Here we review the mechanisms of action of these two sets of microRNAs and their functional implications during the transition from neural stem cells and neural progenitors to fully differentiated neurons. The genetic and epigenetic mechanisms that regulate the expression of these microRNAs as well as the role of the recently described natural RNA circles which act as natural microRNA sponges regulating post-transcriptional microRNA expression and function during the early stages of neurogenesis is also discussed. PMID:25009466

  9. Transcriptome analysis of mammary epithelial subpopulations identifies novel determinants of lineage commitment and cell fate

    PubMed Central

    Kendrick, Howard; Regan, Joseph L; Magnay, Fiona-Ann; Grigoriadis, Anita; Mitsopoulos, Costas; Zvelebil, Marketa; Smalley, Matthew J

    2008-01-01

    Background Understanding the molecular control of cell lineages and fate determination in complex tissues is key to not only understanding the developmental biology and cellular homeostasis of such tissues but also for our understanding and interpretation of the molecular pathology of diseases such as cancer. The prerequisite for such an understanding is detailed knowledge of the cell types that make up such tissues, including their comprehensive molecular characterisation. In the mammary epithelium, the bulk of the tissue is composed of three cell lineages, namely the basal/myoepithelial, luminal epithelial estrogen receptor positive and luminal epithelial estrogen receptor negative cells. However, a detailed molecular characterisation of the transcriptomic differences between these three populations has not been carried out. Results A whole transcriptome analysis of basal/myoepithelial cells, luminal estrogen receptor negative cells and luminal estrogen receptor positive cells isolated from the virgin mouse mammary epithelium identified 861, 326 and 488 genes as highly differentially expressed in the three cell types, respectively. Network analysis of the transcriptomic data identified a subpopulation of luminal estrogen receptor negative cells with a novel potential role as non-professional immune cells. Analysis of the data for potential paracrine interacting factors showed that the basal/myoepithelial cells, remarkably, expressed over twice as many ligands and cell surface receptors as the other two populations combined. A number of transcriptional regulators were also identified that were differentially expressed between the cell lineages. One of these, Sox6, was specifically expressed in luminal estrogen receptor negative cells and functional assays confirmed that it maintained mammary epithelial cells in a differentiated luminal cell lineage. Conclusion The mouse mammary epithelium is composed of three main cell types with distinct gene expression patterns

  10. Fate of retinoic acid-activated embryonic cell lineages.

    PubMed

    Dollé, Pascal; Fraulob, Valérie; Gallego-Llamas, Jabier; Vermot, Julien; Niederreither, Karen

    2010-12-01

    Retinoic acid (RA), a vitamin A derivative, is synthesized by specific cell populations and acts as a diffusible embryonic signal activating ligand-inducible transcription factors, the RA receptors (RARs). RA-activatable transgenic systems have revealed many discrete, transient sites of RA action during development. However, there has been no attempt to permanently label the RA-activated cell lineages during mouse ontogenesis. We describe the characterization of a RA-activatable Cre transgene, which through crosses with a conditional reporter strain (the ROSA26R lacZ reporter), leads to a stable labeling of the cell populations experiencing RA signaling during embryogenesis. RA response-element (RARE)-driven Cre activity mimics at early stages the known activity of the corresponding RARE-lacZ transgene (Rossant et al.,1991). Stable labeling of the Cre-excised cell populations allows to trace the distribution of the RA-activated cell lineages at later stages. These are described in relationship with current models of RA activity in various developmental systems, including the embryonic caudal region, limb buds, hindbrain, sensory organs, and heart. PMID:21046629

  11. Fate decision of mesenchymal stem cells: adipocytes or osteoblasts?

    PubMed Central

    Chen, Q; Shou, P; Zheng, C; Jiang, M; Cao, G; Yang, Q; Cao, J; Xie, N; Velletri, T; Zhang, X; Xu, C; Zhang, L; Yang, H; Hou, J; Wang, Y; Shi, Y

    2016-01-01

    Mesenchymal stem cells (MSCs), a non-hematopoietic stem cell population first discovered in bone marrow, are multipotent cells capable of differentiating into mature cells of several mesenchymal tissues, such as fat and bone. As common progenitor cells of adipocytes and osteoblasts, MSCs are delicately balanced for their differentiation commitment. Numerous in vitro investigations have demonstrated that fat-induction factors inhibit osteogenesis, and, conversely, bone-induction factors hinder adipogenesis. In fact, a variety of external cues contribute to the delicate balance of adipo-osteogenic differentiation of MSCs, including chemical, physical, and biological factors. These factors trigger different signaling pathways and activate various transcription factors that guide MSCs to commit to either lineage. The dysregulation of the adipo-osteogenic balance has been linked to several pathophysiologic processes, such as aging, obesity, osteopenia, osteopetrosis, and osteoporosis. Thus, the regulation of MSC differentiation has increasingly attracted great attention in recent years. Here, we review external factors and their signaling processes dictating the reciprocal regulation between adipocytes and osteoblasts during MSC differentiation and the ultimate control of the adipo-osteogenic balance. PMID:26868907

  12. Neurosensory development and cell fate determination in the human cochlea

    PubMed Central

    2013-01-01

    Background Hearing depends on correct functioning of the cochlear hair cells, and their innervation by spiral ganglion neurons. Most of the insight into the embryological and molecular development of this sensory system has been derived from animal studies. In contrast, little is known about the molecular expression patterns and dynamics of signaling molecules during normal fetal development of the human cochlea. In this study, we investigated the onset of hair cell differentiation and innervation in the human fetal cochlea at various stages of development. Results At 10 weeks of gestation, we observed a prosensory domain expressing SOX2 and SOX9/SOX10 within the cochlear duct epithelium. In this domain, hair cell differentiation was consistently present from 12 weeks, coinciding with downregulation of SOX9/SOX10, to be followed several weeks later by downregulation of SOX2. Outgrowing neurites from spiral ganglion neurons were found penetrating into the cochlear duct epithelium prior to hair cell differentiation, and directly targeted the hair cells as they developed. Ubiquitous Peripherin expression by spiral ganglion neurons gradually diminished and became restricted to the type II spiral ganglion neurons by 18 weeks. At 20 weeks, when the onset of human hearing is thought to take place, the expression profiles in hair cells and spiral ganglion neurons matched the expression patterns of the adult mammalian cochleae. Conclusions Our study provides new insights into the fetal development of the human cochlea, contributing to our understanding of deafness and to the development of new therapeutic strategies to restore hearing. PMID:24131517

  13. Nucleolar release of Hand1 acts as a molecular switch to determine cell fate.

    PubMed

    Martindill, David M J; Risebro, Catherine A; Smart, Nicola; Franco-Viseras, Maria Del Mar; Rosario, Carla O; Swallow, Carol J; Dennis, James W; Riley, Paul R

    2007-10-01

    The bHLH transcription factor Hand1 is essential for placentation and cardiac morphogenesis in the developing embryo. Here we implicate Hand1 as a molecular switch that determines whether a trophoblast stem cell continues to proliferate or commits to differentiation. We identify a novel interaction of Hand1 with a protein that contains an I-mfa (inhibitor of myogenic factor) domain that anchors Hand1 in the nucleolus where it negatively regulates Hand1 activity. In the trophoblast stem-cell line Rcho-1, nucleolar sequestration of Hand1 accompanies sustained cell proliferation and renewal, whereas release of Hand1 into the nucleus leads to its activation, thus committing cells to a differentiated giant-cell fate. Site-specific phosphorylation is required for nucleolar release of Hand1, for its dimerization and biological function, and this is mediated by the non-canonical polo-like kinase Plk4 (Sak). Sak is co-expressed in Rcho-1 cells, localizes to the nucleolus during G2 and phosphorylates Hand1 as a requirement for trophoblast stem-cell commitment to a giant-cell fate. This study defines a novel cellular mechanism for regulating Hand1 that is a crucial step in the stem-cell differentiation pathway.

  14. Cell fate conversion-from the viewpoint of small molecules and lineage specifiers.

    PubMed

    Zhao, T; Li, Y; Deng, H

    2016-09-01

    Mammalian development was generally considered a naturally unidirectional and irreversible process. However, pioneering work of recent decades has highlighted the plasticity of mammalian cells and implied the possibilities of manipulating cell fate in vitro. Pluripotent stem cells, which hold great potential for regenerative medicine, have been shown to be reprogrammed from differentiated cells either by somatic cell nuclear transfer or by ectopic expression of pluripotency factors. Nevertheless, it remained unknown whether the reprogramming could be accomplished without pluripotency genes. Recent studies show that lineage specifiers play an important role in orchestrating the process of restoring pluripotency by replacing pluripotency-associated transcription factors. Moreover, a combination of small molecules enables the acquisition of pluripotency from somatic cells without any transgenes, offering a tractable platform to precisely dissect the induction and maintenance of cell identity. Here, we will discuss recent scientific advances regarding the cell fate conversion mediated by small molecules or lineage specifiers, especially in the chemically induced somatic cell reprogramming process, and will provide new insights into the intermediate plastic state and "seesaw model" established by chemical approaches during reprogramming. PMID:27615126

  15. Expression dynamics of WOX genes mark cell fate decisions during early embryonic patterning in Arabidopsis thaliana.

    PubMed

    Haecker, Achim; Gross-Hardt, Rita; Geiges, Bernd; Sarkar, Ananda; Breuninger, Holger; Herrmann, Marita; Laux, Thomas

    2004-02-01

    During embryonic pattern formation, the main body axes are established and cells of different developmental fates are specified from a single-cell zygote. Despite the fundamental importance of this process, in plants, the underlying mechanisms are largely unknown. We show that expression dynamics of novel WOX (WUSCHEL related homeobox) gene family members reveal early embryonic patterning events in Arabidopsis. WOX2 and WOX8 are co-expressed in the egg cell and zygote and become confined to the apical and basal daughter cells of the zygote, respectively, by its asymmetric division. WOX2 not only marks apical descendants of the zygote, but is also functionally required for their correct development, suggesting that the asymmetric division of the plant zygote separates determinants of apical and basal cell fates. WOX9 expression is initiated in the basal daughter cell of the zygote and subsequently shifts into the descendants of the apical daughter apparently in response to signaling from the embryo proper. Expression of WOX5 shows that identity of the quiescent center is initiated very early in the hypophyseal cell, and highlights molecular and developmental similarities between the stem cell niches of root and shoot meristems. Together, our data suggest that during plant embryogenesis region-specific transcription programs are initiated very early in single precursor cells and that WOX genes play an important role in this process.

  16. Fate of naphthalene in laboratory-scale bioretention cells: implications for sustainable stormwater management.

    PubMed

    Lefevre, Gregory H; Novak, Paige J; Hozalski, Raymond M

    2012-01-17

    Bioretention cells are increasingly popular in low-impact development as a means to sustainably mitigate the environmental problems associated with stormwater runoff. Yet, much remains to be known regarding the removal and ultimate fate of pollutants such as petroleum hydrocarbons in bioretention cells. In this work, laboratory-scale bioretention cells were constructed inside sealed glass columns. The columns were periodically spiked with (14)C-naphthalene over a 5-month period and the fate of this representative hydrocarbon and the influence of vegetation on naphthalene fate was studied. Three column setups were used: one planted with a legume (Purple Prairie Clover, Dalea purpureum), one planted with grass (Blue-Joint Grass, Calamagrostis canadensis), and one unplanted (i.e., control). Overall naphthalene removal efficiency was 93% for the planted columns and 78% for the control column. Adsorption to soil was the dominant naphthalene removal mechanism (56-73% of added naphthalene), although mineralization (12-18%) and plant uptake (2-23%) were also important. Volatilization was negligible (<0.04%). Significant enrichment of naphthalene-degrading bacteria occurred due to contaminant exposure and plant growth as evidenced by increased biodegradation activity and increased naphthalene dioxygenase gene concentrations in the bioretention media. This research suggests that bioretention is a viable solution for sustainable petroleum hydrocarbon removal from stormwater, and that vegetation can enhance overall performance and stimulate biodegradation.

  17. Have We Achieved a Unified Model of Photoreceptor Cell Fate Specification in Vertebrates?

    PubMed Central

    Raymond, Pamela A.

    2008-01-01

    How does a retinal progenitor choose to differentiate as a rod or a cone and, if it becomes a cone, which one of their different subtypes? The mechanisms of photoreceptor cell fate specification and differentiation have been extensively investigated in a variety of animal model systems, including human and non-human primates, rodents (mice and rats), chickens, frogs (Xenopus) and fish. It appears timely to discuss whether it is possible to synthesize the resulting information into a unified model applicable to all vertebrates. In this review we focus on several widely used experimental animal model systems to highlight differences in photoreceptor properties among species, the diversity of developmental strategies and solutions that vertebrates use to create retinas with photoreceptors that are adapted to the visual needs of their species, and the limitations of the methods currently available for the investigation of photoreceptor cell fate specification. Based on these considerations, we conclude that we are not yet ready to construct a unified model of photoreceptor cell fate specification in the developing vertebrate retina. PMID:17466954

  18. Oriented growth and transdifferentiation of mesenchymal stem cells towards a Schwann cell fate on micropatterned substrates.

    PubMed

    Sharma, Anup D; Zbarska, Svitlana; Petersen, Emma M; Marti, Mustafa E; Mallapragada, Surya K; Sakaguchi, Donald S

    2016-03-01

    While Schwann cells (SCs) have a significant role in peripheral nerve regeneration, their use in treatments has been limited because of lack of a readily available source. To address this issue, this study focused on the effect of guidance cues by employing micropatterned polymeric films to influence the alignment, morphology and transdifferentiation of bone marrow-derived rat mesenchymal stem cells (MSCs) towards a Schwann cell-like fate. Two different types of polymers, biocompatible polystyrene (PS) and biodegradable poly(lactic acid) (PLA) were used to fabricate patterned films. Percentages of transdifferentiated MSCs (tMSCs) immunolabeled with SC markers (α-S100β and α-p75(NTR)) were found to be similar on patterned versus smooth PS and PLA substrates. However, patterning had a significant effect on the alignment and elongation of the tMSCs. More than 80% of the tMSCs were oriented in the direction of microgrooves (0°-20°), while cells on the smooth substrates were randomly oriented. The aspect ratio [AR, ratio of length (in direction of microgrooves) and breadth (in direction perpendicular to microgrooves)] of the tMSCs on patterned substrates had a value of approximately five, as compared to cells on smooth substrates where the AR was one. Understanding responses to these cues in vitro helps us in understanding the behavior and interaction of the cells with the 3D environment of the scaffolds, facilitating the application of these concepts to designing effective nerve guidance conduits for peripheral nerve regeneration.

  19. Somatic embryogenesis - Stress-induced remodeling of plant cell fate.

    PubMed

    Fehér, Attila

    2015-04-01

    Plants as sessile organisms have remarkable developmental plasticity ensuring heir continuous adaptation to the environment. An extreme example is somatic embryogenesis, the initiation of autonomous embryo development in somatic cells in response to exogenous and/or endogenous signals. In this review I briefly overview the various pathways that can lead to embryo development in plants in addition to the fertilization of the egg cell and highlight the importance of the interaction of stress- and hormone-regulated pathways during the induction of somatic embryogenesis. Somatic embryogenesis can be initiated in planta or in vitro, directly or indirectly, and the requirement for dedifferentiation as well as the way to achieve developmental totipotency in the various systems is discussed in light of our present knowledge. The initiation of all forms of the stress/hormone-induced in vitro as well as the genetically provoked in planta somatic embryogenesis requires extensive and coordinated genetic reprogramming that has to take place at the chromatin level, as the embryogenic program is under strong epigenetic repression in vegetative plant cells. Our present knowledge on chromatin-based mechanisms potentially involved in the somatic-to-embryogenic developmental transition is summarized emphasizing the potential role of the chromatin to integrate stress, hormonal, and developmental pathways leading to the activation of the embryogenic program. The role of stress-related chromatin reorganization in the genetic instability of in vitro cultures is also discussed. This article is part of a Special Issue entitled: Stress as a fundamental theme in cell plasticity.

  20. Capturing Identity and Fate Ex Vivo: Stem Cells from the Mouse Blastocyst.

    PubMed

    Garg, V; Morgani, S; Hadjantonakis, A-K

    2016-01-01

    During mouse preimplantation development, three molecularly, morphologically, and spatially distinct lineages are formed, the embryonic epiblast, the extraembryonic primitive endoderm, and the trophectoderm. Stem cell lines representing each of these lineages have now been derived and can be indefinitely maintained and expanded in culture, providing an unlimited source of material to study the interplay of tissue-specific transcription factors and signaling pathways involved in these fundamental cell fate decisions. Here we outline our current understanding of the derivation, maintenance, and properties of these in vitro stem cell models representing the preimplantation embryonic lineages. PMID:27475857

  1. Ubiquitin Ligases and Deubiquitinating Enzymes in CD4+ T Cell Effector Fate Choice and Function.

    PubMed

    Layman, Awo A K; Oliver, Paula M

    2016-05-15

    The human body is exposed to potentially pathogenic microorganisms at barrier sites such as the skin, lungs, and gastrointestinal tract. To mount an effective response against these pathogens, the immune system must recruit the right cells with effector responses that are appropriate for the task at hand. Several types of CD4(+) T cells can be recruited, including Th cells (Th1, Th2, and Th17), T follicular helper cells, and regulatory T cells. These cells help to maintain normal immune homeostasis in the face of constantly changing microbes in the environment. Because these cells differentiate from a common progenitor, the composition of their intracellular milieu of proteins changes to appropriately guide their effector function. One underappreciated process that impacts the levels and functions of effector fate-determining factors is ubiquitylation. This review details our current understanding of how ubiquitylation regulates CD4(+) T cell effector identity and function.

  2. The fate of arsenic in sediments formed at a river confluence affected by acid mine drainage

    NASA Astrophysics Data System (ADS)

    Guerra, P. A.; Pasten, P. A.; Pizarro, G.; Simonson, K.; Escauriaza, C. R.; Gonzalez, C.; Bonilla, C.

    2012-12-01

    Fluvial confluences receiving acid mine drainage may play a critical role in a watershed as a suite of interactions between chemistry and hydrodynamics occur, determining the fate of toxic contaminants like arsenic. Solid reactive phases of iron and/or aluminum oxi-hydroxides may form or transform, ranging from iron oxide nanoparticles that aggregate and form floccules that are transported in the suspended load up to gravel and arsenic-rich rock coatings. In order to further understand the role of reactive fluvial confluences, we have studied the mixing between the Caracarani River (flow=170-640 L/s, pH 8, conductivity 1.5 mS/cm, total As<0.1 mg/L and total Fe< 5 mg/L) and the Azufre River (flow=45-245 L/s, pH<2, conductivity > 10 mS/cm, total As>2 mg/L, total Fe=35-125 mg/L), located in the Lluta watershed in northern Chile. This site is an excellent natural laboratory located in a water-scarce area, where the future construction of a dam has prompted the attention of decision makers and scientists interested in weighing the risks derived by the accumulation of arsenic-rich sediments. Suspended sediments (> 0.45 μm), riverbed sediments, and coated rocks were collected upstream and downstream from the confluence. Suspended sediments >0.45 μm and riverbed sediments were analyzed by total reflection x-ray fluorescence for metals, while coated river bed rocks were analyzed by chemical extractions and a semi-quantitative approach through portable x-ray fluorescence. Water from the Caracarani and Azufre rivers were mixed in the laboratory at different ratios and mixing velocities aiming to characterize the effect of the chemical-hydrodynamic environment where arsenic solids were formed at different locations in the confluence. Despite a wide range of iron and arsenic concentrations in the suspended sediments from the field (As=1037 ± 1372 mg/kg, Fe=21.0 ± 24.5 g/kg), we found a rather narrow As/Fe ratio, increasing from 36.5 to 55.2 mgAs/kgFe when the bulk water p

  3. Physical factors affecting the transport and fate of colloids in saturated porous media

    NASA Astrophysics Data System (ADS)

    Bradford, Scott A.; Yates, Scott R.; Bettahar, Mehdi; Simunek, Jirka

    2002-12-01

    Saturated soil column experiments were conducted to explore the influence of colloid size and soil grain size distribution characteristics on the transport and fate of colloid particles in saturated porous media. Stable monodispersed colloids and porous media that are negatively charged were employed in these studies. Effluent colloid concentration curves and the final spatial distribution of retained colloids by the porous media were found to be highly dependent on the colloid size and soil grain size distribution. Relative peak effluent concentrations decreased and surface mass removal by the soil increased when the colloid size increased and the soil median grain size decreased. These observations were attributed to increased straining of the colloids; i.e., blocked pores act as dead ends for the colloids. When the colloid size is small relative to the soil pore sizes, straining becomes a less significant mechanism of colloid removal and attachment becomes more important. Mathematical modeling of the colloid transport experiments using traditional colloid attachment theory was conducted to highlight differences in colloid attachment and straining behavior and to identify parameter ranges that are applicable for attachment models. Simulated colloid effluent curves using fitted first-order attachment and detachment parameters were able to describe much of the effluent concentration data. The model was, however, less adequate at describing systems which exhibited a gradual approach to the peak effluent concentration and the spatial distribution of colloids when significant mass was retained in the soil. Current colloid filtration theory did not adequately predict the fitted first-order attachment coefficients, presumably due to straining in these systems.

  4. Factors affecting atrazine fate in north central U.S. soils.

    PubMed

    Koskinen, W C; Clay, S A

    1997-01-01

    Atrazine persistence and fate are influenced by many factors, the interactions of which are difficult to predict. Several models, such as LEACHP (Wagenet and Hutson 1989), have been used as tools to estimate losses and identify variables that will impact the magnitude of loss. The LEACHP model was evaluated for predicting atrazine movement in sandy loam, silt loam, and clay loam soils during three consecutive years (two dry and one wet) in Minnesota (Khakural et al. 1995). Considering the broad range in soil properties and climatic conditions used in testing, the model performed well. However, these are only estimates, and additional field studies need to be conducted to verify model results. In a report by Fausey et al. (1995), the amount of atrazine found in groundwater throughout the Midwestern region was reported to be much below the MCL. However, specific sites in the Midwest may struggle with atrazine problems from both point and nonpoint sources of contamination. Some states, such as South Dakota, have created groundwater protection areas that alert growers and the public to sensitive areas where contamination may occur because of soil type, depth to groundwater, and distance to public wellheads. Wisconsin has developed a tiered managerial strategy, or zoning approach, in which restrictions are matched to pollution detections (Wolf and Nowak 1996). The USEPA has mandates for states to implement generic management plans to prevent pesticide contamination of groundwater. Chemical-specific plans by states will be required for at least five pesticides, one of which will be atrazine. Best management practices have been and are continuing to be developed to aid the grower in lessening the adverse impacts of atrazine. With continuing research into understanding the problem and developing solutions, and with adaptation of these recommendations by growers, the use of effective, inexpensive herbicides may continue with minimal off-site environmental effects.

  5. Processes affecting the fate of monoaromatic hydrocarbons in an aquifer contaminated by crude oil

    USGS Publications Warehouse

    Eganhouse, R.P.; Dorsey, T.F.; Phinney, C.S.; Westcott, A.M.

    1996-01-01

    Crude oil spilled from a subsurface pipeline in north-central Minnesota has dissolved in the groundwater, resulting in the formation of a plume of aliphatic, aromatic, and alicyclic hydrocarbons. Comparison of paired oil and groundwater samples collected along the central axis of the residual oil body shows that the trailing edge of the oil is depleted in the more soluble aromatic hydrocarbons (e.g., benzene, toluene, etc.) when compared with the leading edge. At the same time, concentrations of monoaromatic hydrocarbons in groundwater beneath the oil increase as the water moves toward the leading edge of the oil. Immediately downgradient from the leading edge of the oil body, certain aromatic hydrocarbons (e.g., benzene) are found at concentrations near those expected of a system at equilibrium, and the concentrations exhibit little variation over time (???8-20%). Other compounds (e.g., toluene) appear to be undersaturated, and their concentrations show considerably more temporal variation (???20-130%). The former are persistent within the anoxic zone downgradient from the oil, whereas concentrations of the latter decrease rapidly. Together, these observations suggest that the volatile hydrocarbon composition of the anoxic groundwater near the oil body is controlled by a balance between dissolution and removal rates with only the most persistent compounds reaching saturation. Examination of the distributions of homologous series and isomeric assemblages of alkylbenzenes reveals that microbial degradation is the dominant process controlling the fate of these compounds once groundwater moves away from the oil. For all but the most persistent compounds, the distal boundary of the plume at the water table extends no more than 10-15 m down-gradient from the oxic/anoxic transition zone. Thus, transport of the monoaromatic hydrocarbons is limited by redox conditions that are tightly coupled to biological degradation processes.

  6. Skeletal cell fate decisions within periosteum and bone marrow during bone regeneration.

    PubMed

    Colnot, Céline

    2009-02-01

    Bone repair requires the mobilization of adult skeletal stem cells/progenitors to allow deposition of cartilage and bone at the injury site. These stem cells/progenitors are believed to come from multiple sources including the bone marrow and the periosteum. The goal of this study was to establish the cellular contributions of bone marrow and periosteum to bone healing in vivo and to assess the effect of the tissue environment on cell differentiation within bone marrow and periosteum. Results show that periosteal injuries heal by endochondral ossification, whereas bone marrow injuries heal by intramembranous ossification, indicating that distinct cellular responses occur within these tissues during repair. [corrected] Next, lineage analyses were used to track the fate of cells derived from periosteum, bone marrow, and endosteum, a subcompartment of the bone marrow. Skeletal progenitor cells were found to be recruited locally and concurrently from periosteum and/or bone marrow/endosteum during bone repair. Periosteum and bone marrow/endosteum both gave rise to osteoblasts, whereas the periosteum was the major source of chondrocytes. Finally, results show that intrinsic and environmental signals modulate cell fate decisions within these tissues. In conclusion, this study sheds light into the origins of skeletal stem cells/progenitors during bone regeneration and indicates that periosteum, endosteum, and bone marrow contain pools of stem cells/progenitors with distinct osteogenic and chondrogenic potentials that vary with the tissue environment.

  7. Fate of deposited cells in an aerobic binary bacterial biofilm

    SciTech Connect

    Banks, M.K.

    1989-01-01

    A biofilm is a matrix of microbial cells and their extracellular products that is associated with a solid surface. Previous studies on biofilm development have employed only dissolved compounds as growth limiting substrates, without the influence of microbial species invading from the bulk liquid. The goal of this research project was to quantify the kinetics of processes governing suspended biomass turnover in biofilm systems, and the accompanying effects of suspended cell deposition on biofilm population dynamics. Experiments were conducted with two species of bacteria, Pseudomonas putida ATCC 11172 grown on glucose, and Hyphomicrobium ZV620 grown on methanol. Cryptic growth and particulate hydrolysis studies were evaluated, using combinations of these two bacteria, by measuring the uptake of radiolabelled cell lysis products, under batch conditions. Biofilms studies were performed to investigate bacterial deposition, continual biofilm removal by shear induced erosion, and biofilm ecology. Biofilms were developed in a flow cell reactor, under laminar flow conditions. Bacterial species were differentiated by radioactively labelling each species with their carbon substrate. A mathematical model was developed to predict the biofilm ecology of mixed cultures. The equations developed predict biofilm accumulation, as well as substrate and oxygen consumption. Results indicate that cryptic growth will occur for bacteria growing on their own species soluble lysis products and in some cases, bacteria growing on the soluble lysis products of other species. Particulate hydrolysis only occurred for Pseudomonas putida growing on Pseudomonas putida lysis products, but the lack of particulate hydrolysis occurring in the other studies may have been due to the short experimental period.

  8. Cell-Type-Specific Alternative Splicing Governs Cell Fate in the Developing Cerebral Cortex.

    PubMed

    Zhang, Xiaochang; Chen, Ming Hui; Wu, Xuebing; Kodani, Andrew; Fan, Jean; Doan, Ryan; Ozawa, Manabu; Ma, Jacqueline; Yoshida, Nobuaki; Reiter, Jeremy F; Black, Douglas L; Kharchenko, Peter V; Sharp, Phillip A; Walsh, Christopher A

    2016-08-25

    Alternative splicing is prevalent in the mammalian brain. To interrogate the functional role of alternative splicing in neural development, we analyzed purified neural progenitor cells (NPCs) and neurons from developing cerebral cortices, revealing hundreds of differentially spliced exons that preferentially alter key protein domains-especially in cytoskeletal proteins-and can harbor disease-causing mutations. We show that Ptbp1 and Rbfox proteins antagonistically govern the NPC-to-neuron transition by regulating neuron-specific exons. Whereas Ptbp1 maintains apical progenitors partly through suppressing a poison exon of Flna in NPCs, Rbfox proteins promote neuronal differentiation by switching Ninein from a centrosomal splice form in NPCs to a non-centrosomal isoform in neurons. We further uncover an intronic human mutation within a PTBP1-binding site that disrupts normal skipping of the FLNA poison exon in NPCs and causes a brain-specific malformation. Our study indicates that dynamic control of alternative splicing governs cell fate in cerebral cortical development.

  9. Rare amplicons implicate frequent deregulation of cell fate specification pathways in oral squamous cell carcinoma.

    PubMed

    Snijders, Antoine M; Schmidt, Brian L; Fridlyand, Jane; Dekker, Nusi; Pinkel, Daniel; Jordan, Richard C K; Albertson, Donna G

    2005-06-16

    Genomes of solid tumors are characterized by gains and losses of regions, which may contribute to tumorigenesis by altering gene expression. Often the aberrations are extensive, encompassing whole chromosome arms, which makes identification of candidate genes in these regions difficult. Here, we focused on narrow regions of gene amplification to facilitate identification of genetic pathways important in oral squamous cell carcinoma (SCC) development. We used array comparative genomic hybridization (array CGH) to define minimum common amplified regions and then used expression analysis to identify candidate driver genes in amplicons that spanned <3 Mb. We found genes involved in integrin signaling (TLN1), survival (YAP1, BIRC2), and adhesion and migration (TLN1, LAMA3, MMP7), as well as members of the hedgehog (GLI2) and notch (JAG1, RBPSUH, FJX1) pathways to be amplified and overexpressed. Deregulation of these and other members of the hedgehog and notch pathways (HHIP, SMO, DLL1, NOTCH4) implicates deregulation of developmental and differentiation pathways, cell fate misspecification, in oral SCC development. PMID:15824737

  10. Cell-Type-Specific Alternative Splicing Governs Cell Fate in the Developing Cerebral Cortex.

    PubMed

    Zhang, Xiaochang; Chen, Ming Hui; Wu, Xuebing; Kodani, Andrew; Fan, Jean; Doan, Ryan; Ozawa, Manabu; Ma, Jacqueline; Yoshida, Nobuaki; Reiter, Jeremy F; Black, Douglas L; Kharchenko, Peter V; Sharp, Phillip A; Walsh, Christopher A

    2016-08-25

    Alternative splicing is prevalent in the mammalian brain. To interrogate the functional role of alternative splicing in neural development, we analyzed purified neural progenitor cells (NPCs) and neurons from developing cerebral cortices, revealing hundreds of differentially spliced exons that preferentially alter key protein domains-especially in cytoskeletal proteins-and can harbor disease-causing mutations. We show that Ptbp1 and Rbfox proteins antagonistically govern the NPC-to-neuron transition by regulating neuron-specific exons. Whereas Ptbp1 maintains apical progenitors partly through suppressing a poison exon of Flna in NPCs, Rbfox proteins promote neuronal differentiation by switching Ninein from a centrosomal splice form in NPCs to a non-centrosomal isoform in neurons. We further uncover an intronic human mutation within a PTBP1-binding site that disrupts normal skipping of the FLNA poison exon in NPCs and causes a brain-specific malformation. Our study indicates that dynamic control of alternative splicing governs cell fate in cerebral cortical development. PMID:27565344

  11. Asymmetric cell division in the Drosophila bristle lineage: from the polarization of sensory organ precursor cells to Notch-mediated binary fate decision.

    PubMed

    Schweisguth, François

    2015-01-01

    Asymmetric cell division (ACD) is a simple and evolutionary conserved process whereby a mother divides to generate two daughter cells with distinct developmental potentials. This process can generate cell fate diversity during development. Fate asymmetry may result from the unequal segregation of molecules and/or organelles between the two daughter cells. Here, I will review how fate asymmetry is regulated in the sensory bristle lineage in Drosophila and focus on the molecular mechanisms underlying ACD of the sensory organ precursor cells (SOPs). For further resources related to this article, please visit the WIREs website.

  12. Nkx2.2 and Nkx2.9 Are the Key Regulators to Determine Cell Fate of Branchial and Visceral Motor Neurons in Caudal Hindbrain

    PubMed Central

    Jarrar, Wassan; Dias, Jose M.; Ericson, Johan; Arnold, Hans-Henning; Holz, Andreas

    2015-01-01

    Cranial motor nerves in vertebrates are comprised of the three principal subtypes of branchial, visceral, and somatic motor neurons, which develop in typical patterns along the anteroposterior and dorsoventral axes of hindbrain. Here we demonstrate that the formation of branchial and visceral motor neurons critically depends on the transcription factors Nkx2.2 and Nkx2.9, which together determine the cell fate of neuronal progenitor cells. Disruption of both genes in mouse embryos results in complete loss of the vagal and spinal accessory motor nerves, and partial loss of the facial and glossopharyngeal motor nerves, while the purely somatic hypoglossal and abducens motor nerves are not diminished. Cell lineage analysis in a genetically marked mouse line reveals that alterations of cranial nerves in Nkx2.2; Nkx2.9 double-deficient mouse embryos result from changes of cell fate in neuronal progenitor cells. As a consequence progenitors of branchiovisceral motor neurons in the ventral p3 domain of hindbrain are transformed to somatic motor neurons, which use ventral exit points to send axon trajectories to their targets. Cell fate transformation is limited to the caudal hindbrain, as the trigeminal nerve is not affected in double-mutant embryos suggesting that Nkx2.2 and Nkx2.9 proteins play no role in the development of branchiovisceral motor neurons in hindbrain rostral to rhombomere 4. PMID:25919494

  13. Polarity and cell fate specification in the control of C. elegans gastrulation

    PubMed Central

    Rohrschneider, Monica R.; Nance, Jeremy

    2010-01-01

    Gastrulation is a time during development when cells destined to produce internal tissues and organs move from the surface of the embryo into the interior. It is critical that the cell movements of gastrulation be precisely controlled, and coordinated with cell specification, in order for the embryo to develop normally. C. elegans gastrulation is relatively simple, can be observed easily in the transparent embryo, and can be manipulated genetically to uncover important regulatory mechanisms. Many of these cellular and molecular mechanisms – including cell shape, cytoskeletal, and cell cycle changes – appear to be conserved from flies to vertebrates. Here we review gastrulation in C. elegans, with an emphasis on recent data linking contact-induced cell polarity, PAR proteins, and cell fate specification to gastrulation control. PMID:19253398

  14. Laminopathies disrupt epigenomic developmental programs and cell fate

    PubMed Central

    Perovanovic, Jelena; Dell’Orso, Stefania; Gnochi, Viola F.; Jaiswal, Jyoti K.; Sartorelli, Vittorio; Vigouroux, Corinne; Mamchaoui, Kamel; Mouly, Vincent; Bonne, Gisèle; Hoffman, Eric P.

    2016-01-01

    The nuclear envelope protein lamin A is encoded by the lamin A/C (LMNA) gene, which can contain missense mutations that cause Emery-Dreifuss muscular dystrophy (EDMD) (p.R453W). We fused mutated forms of the lamin A protein to bacterial DNA adenine methyltransferase (Dam) to define euchromatic-heterochromatin (epigenomic) transitions at the nuclear envelope during myogenesis (using DamID-seq). Lamin A missense mutations disrupted appropriate formation of lamin A–associated heterochromatin domains in an allele-specific manner—findings that were confirmed by chromatin immunoprecipitation–DNA sequencing (ChIP-seq) in murine H2K cells and DNA methylation studies in fibroblasts from muscular dystrophy patient who carried a distinct LMNA mutation (p.H222P). Observed perturbations of the epigenomic transitions included exit from pluripotency and cell cycle programs [euchromatin (open, transcribed) to heterochromatin (closed, silent)], as well as induction of myogenic loci (heterochromatin to euchromatin). In muscle biopsies from patients with either a gain- or change-of-function LMNA gene mutation or a loss-of-function mutation in the emerin gene, both of which cause EDMD, we observed inappropriate loss of heterochromatin formation at the Sox2 pluripotency locus, which was associated with persistent mRNA expression of Sox2. Overexpression of Sox2 inhibited myogenic differentiation in human immortalized myoblasts. Our findings suggest that nuclear envelopathies are disorders of developmental epigenetic programming that result from altered formation of lamina-associated domains. PMID:27099177

  15. Fate study of water-borne gram positive vegetative bacterial cells with Raman microscopy

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Tripathi, Ashish; Minter, Jennifer; Wilcox, Phillip; Christesen, Steven

    2010-04-01

    We present an initial bacterial fate study of Gram positive vegetative cells suspended in water and stored at ambient room temperature via Raman spectroscopy monitoring. Two types of cells were considered for this study: vegetative cells of Bacillus cereus, Bacillus thuringiensis which contain the polyhydroxybutyric acid (PHBA) as an energy storage compound and Bacillus subtlilis cells which do not. The cells were cultured specifically for this project. Immediately following the culturing phase, the bacteria were extracted, cleaned and at the onset of the study were suspended in de-ionized water and stored at room temperature. Aliquots of suspensions were deposited onto aluminum slides at different times and allowed to dry for Raman analysis. Spectra from multiple regions of each dried spot and each deposit time were acquired along with the bright-field and fluorescence images. Results were examined to investigate the effect of suspension time on the spectral signatures as well as the fate behavior of the three types of cells investigated. The cells were monitored daily for over a 14 period during which time the onset of starvation induced sporulation was observed.

  16. Effector, Memory, and Dysfunctional CD8+ T Cell Fates in the Antitumor Immune Response

    PubMed Central

    2016-01-01

    The adaptive immune system plays a pivotal role in the host's ability to mount an effective, antigen-specific immune response against tumors. CD8+ tumor-infiltrating lymphocytes (TILs) mediate tumor rejection through recognition of tumor antigens and direct killing of transformed cells. In growing tumors, TILs are often functionally impaired as a result of interaction with, or signals from, transformed cells and the tumor microenvironment. These interactions and signals can lead to transcriptional, functional, and phenotypic changes in TILs that diminish the host's ability to eradicate the tumor. In addition to effector and memory CD8+ T cells, populations described as exhausted, anergic, senescent, and regulatory CD8+ T cells have been observed in clinical and basic studies of antitumor immune responses. In the context of antitumor immunity, these CD8+ T cell subsets remain poorly characterized in terms of fate-specific biomarkers and transcription factor profiles. Here we discuss the current characterization of CD8+ T cell fates in antitumor immune responses and discuss recent insights into how signals in the tumor microenvironment influence TIL transcriptional networks to promote CD8+ T cell dysfunction. PMID:27314056

  17. Lineage Tracing Reveals Distinctive Fates for Mesothelial Cells and Submesothelial Fibroblasts during Peritoneal Injury

    PubMed Central

    Chen, Yi-Ting; Chang, Yu-Ting; Pan, Szu-Yu; Chou, Yu-Hsiang; Chang, Fan-Chi; Yeh, Pei-Ying; Liu, Yuan-Hung; Chiang, Wen-Chih; Chen, Yung-Ming; Wu, Kwan-Dun; Tsai, Tun-Jun; Duffield, Jeremy S.

    2014-01-01

    Fibrosis of the peritoneal cavity remains a serious, life-threatening problem in the treatment of kidney failure with peritoneal dialysis. The mechanism of fibrosis remains unclear partly because the fibrogenic cells have not been identified with certainty. Recent studies have proposed mesothelial cells to be an important source of myofibroblasts through the epithelial–mesenchymal transition; however, confirmatory studies in vivo are lacking. Here, we show by inducible genetic fate mapping that type I collagen–producing submesothelial fibroblasts are specific progenitors of α-smooth muscle actin–positive myofibroblasts that accumulate progressively in models of peritoneal fibrosis induced by sodium hypochlorite, hyperglycemic dialysis solutions, or TGF-β1. Similar genetic mapping of Wilms’ tumor-1–positive mesothelial cells indicated that peritoneal membrane disruption is repaired and replaced by surviving mesothelial cells in peritoneal injury, and not by submesothelial fibroblasts. Although primary cultures of mesothelial cells or submesothelial fibroblasts each expressed α-smooth muscle actin under the influence of TGF-β1, only submesothelial fibroblasts expressed α-smooth muscle actin after induction of peritoneal fibrosis in mice. Furthermore, pharmacologic inhibition of the PDGF receptor, which is expressed by submesothelial fibroblasts but not mesothelial cells, attenuated the peritoneal fibrosis but not the remesothelialization induced by hypochlorite. Thus, our data identify distinctive fates for injured mesothelial cells and submesothelial fibroblasts during peritoneal injury and fibrosis. PMID:24854266

  18. Runx2 is a novel regulator of mammary epithelial cell fate in development and breast cancer

    PubMed Central

    Best, Sarah; Ledger, Anita; Mooney, Anne-Marie; Ferguson, Alison; Shore, Paul; Swarbrick, Alexander; Ormandy, Christopher J; Simpson, Peter T; Carroll, Jason S; Visvader, Jane; Naylor, Matthew J

    2014-01-01

    Regulators of differentiated cell fate can offer targets for managing cancer development and progression. Here we identify Runx2 as a new regulator of epithelial cell fate in mammary gland development and breast cancer. Runx2 is expressed in the epithelium of pregnant mice in a strict temporally and hormonally-regulated manner. During pregnancy, Runx2 genetic deletion impaired alveolar differentiation in a manner that disrupted alveolar progenitor cell populations. Conversely, exogenous transgenic expression of Runx2 in mammary epithelial cells blocked milk production, suggesting that the decrease in endogenous Runx2 observed late in pregnancy is necessary for full differentiation. In addition, overexpression of Runx2 drove EMT-like changes in normal mammary epithelial cells, while Runx2 deletion in basal breast cancer cells inhibited cellular phenotypes associated with tumorigenesis. Notably, loss of Runx2 expression increased tumor latency and enhanced overall survival in a mouse model of breast cancer, with Runx2-deficient tumors exhibiting reduced cell proliferation. Together, our results establish a novel function for Runx2 in breast cancer that may offer a novel generalized route for therapeutic interventions. PMID:25056120

  19. Specification of haematopoietic stem cell fate via modulation of mitochondrial activity

    PubMed Central

    Vannini, Nicola; Girotra, Mukul; Naveiras, Olaia; Nikitin, Gennady; Campos, Vasco; Giger, Sonja; Roch, Aline; Auwerx, Johan; Lutolf, Matthias P.

    2016-01-01

    Haematopoietic stem cells (HSCs) differ from their committed progeny by relying primarily on anaerobic glycolysis rather than mitochondrial oxidative phosphorylation for energy production. However, whether this change in the metabolic program is the cause or the consequence of the unique function of HSCs remains unknown. Here we show that enforced modulation of energy metabolism impacts HSC self-renewal. Lowering the mitochondrial activity of HSCs by chemically uncoupling the electron transport chain drives self-renewal under culture conditions that normally induce rapid differentiation. We demonstrate that this metabolic specification of HSC fate occurs through the reversible decrease of mitochondrial mass by autophagy. Our data thus reveal a causal relationship between mitochondrial metabolism and fate choice of HSCs and also provide a valuable tool to expand HSCs outside of their native bone marrow niches. PMID:27731316

  20. ABSENCE OF SCLEROSTIN ADVERSELY AFFECTS B CELL SURVIVAL

    PubMed Central

    Cain, Corey J.; Rueda, Randell; McLelland, Bryce; Collette, Nicole M.; Loots, Gabriela G.; Manilay, Jennifer O.

    2012-01-01

    Increased osteoblast activity in sclerostin-knockout (Sost−/−) mice results in generalized hyperostosis and bones with small bone marrow cavities due to hyperactive mineralizing osteoblast populations. Hematopoietic cell fate decisions are dependent on their local microenvironment, which contains osteoblast and stromal cell populations that support both hematopoietic stem cell quiescence and facilitate B cell development. In this study, we investigated whether high bone mass environments affect B cell development via the utilization of Sost−/− mice, a model of sclerosteosis. We found the bone marrow of Sost−/− mice to be specifically depleted of B cells, due to elevated apoptosis at all B cell developmental stages. In contrast, B cell function in the spleen was normal. Sost expression analysis confirmed that Sost is primarily expressed in osteocytes and is not expressed in any hematopoietic lineage, which indicated that the B cell defects in Sost−/− mice are non-cell autonomous and this was confirmed by transplantation of wildtype (WT) bone marrow into lethally irradiated Sost−/− recipients. WT→Sost−/− chimeras displayed a reduction in B cells, whereas reciprocal Sost−/−→WT chimeras did not, supporting the idea that the Sost−/− bone environment cannot fully support normal B cell development. Expression of the pre-B cell growth stimulating factor, Cxcl12, was significantly lower in bone marrow stromal cells of Sost−/− mice while the Wnt target genes Lef-1 and Ccnd1 remained unchanged in B cells. Taken together, these results demonstrate a novel role for Sost in the regulation of bone marrow environments that support B cells. PMID:22434688

  1. Synthetic Substrata to Instruct Human Pluripotent Stem Cell Fate: From Novel Ligands to Functional Biomaterials

    NASA Astrophysics Data System (ADS)

    Musah, Samira

    Human pluripotent stem (hPS) cells have the remarkable capacity to self-renew indefinitely and differentiate into desired cell types. They can serve as a virtually unlimited supply of cells for applications ranging from drug screening to cell therapies to understanding human development. Reaping the promise of hPS cells hinges on effective defined culture and differentiation conditions. Efforts to generate chemically-defined environments for hPS cell propagation and directed differentiation have been hindered by access to only a handful of ligands to target hPS cells. Additionally, progress has been limited also by lack of knowledge regarding the relevant functional properties of the cell culture substratum. To address these problems, I first employed forward-chemical-genetics coupled with self-assembled monolayer technology to identify novel peptides that bind to hPS cell-surface receptors. I then developed a controlled synthesis of hydrogels with tailored peptide display and mechanical properties. This approach yielded synthetic hydrogels with specific mechanical properties that function in a defined medium to robustly support hPS cell self-renewal. Finally, by starting from molecular level understanding that matrix elasticity regulates developmental pathways, I generated a highly efficient hydrogel platform that restricts hPS cell differentiation to neurons, even without soluble inductive factors. These results indicate that insoluble cues can be important information conduits to guide hPS cell fate decisions. I envision that the blueprint provided by this work can be utilized to devise new materials to guide hPS cell fate.

  2. Antibodies from combinatorial libraries use functional receptor pleiotropism to regulate cell fates.

    PubMed

    Lerner, Richard A; Grover, Rajesh K; Zhang, Hongkai; Xie, Jia; Han, Kyung Ho; Peng, Yingjie; Yea, Kyungmoo

    2015-11-01

    To date, most antibodies from combinatorial libraries have been selected purely on the basis of binding. However, new methods now allow selection on the basis of function in animal cells. These selected agonist antibodies have given new insights into the important problem of signal transduction. Remarkably, when some antibodies bind to a given receptor they induce a cell fate that is different than that induced by the natural agonist to the same receptor. The fact that receptors can be functionally pleiotropic may yield new insights into the important problem of signal transduction.

  3. Using cell fate attractors to uncover transcriptional regulation of HL60 neutrophil differentiation

    PubMed Central

    Huang, Albert C; Hu, Limei; Kauffman, Stuart A; Zhang, Wei; Shmulevich, Ilya

    2009-01-01

    Background The process of cellular differentiation is governed by complex dynamical biomolecular networks consisting of a multitude of genes and their products acting in concert to determine a particular cell fate. Thus, a systems level view is necessary for understanding how a cell coordinates this process and for developing effective therapeutic strategies to treat diseases, such as cancer, in which differentiation plays a significant role. Theoretical considerations and recent experimental evidence support the view that cell fates are high dimensional attractor states of the underlying molecular networks. The temporal behavior of the network states progressing toward different cell fate attractors has the potential to elucidate the underlying molecular mechanisms governing differentiation. Results Using the HL60 multipotent promyelocytic leukemia cell line, we performed experiments that ultimately led to two different cell fate attractors by two treatments of varying dosage and duration of the differentiation agent all-trans-retinoic acid (ATRA). The dosage and duration combinations of the two treatments were chosen by means of flow cytometric measurements of CD11b, a well-known early differentiation marker, such that they generated two intermediate populations that were poised at the apparently same stage of differentiation. However, the population of one treatment proceeded toward the terminally differentiated neutrophil attractor while that of the other treatment reverted back toward the undifferentiated promyelocytic attractor. We monitored the gene expression changes in the two populations after their respective treatments over a period of five days and identified a set of genes that diverged in their expression, a subset of which promotes neutrophil differentiation while the other represses cell cycle progression. By employing promoter based transcription factor binding site analysis, we found enrichment in the set of divergent genes, of transcription

  4. Stencil Micropatterning for Spatial Control of Human Pluripotent Stem Cell Fate Heterogeneity.

    PubMed

    Yuan, Jun; Sahni, Geetika; Toh, Yi-Chin

    2016-01-01

    Human pluripotent stem cells (hPSCs) have the intrinsic ability to differentiate and self-organize into distinct tissue patterns, although this requires the presentation of spatial environmental cues, i.e., biochemical and mechanical gradients. Cell micropatterning technologies potentially offer the means to spatially control stem cell microenvironments and organize the resultant differentiation fates. Here, we describe stencil micropatterning as a simple and robust method to generate hPSC micropatterns for controlling hPSC differentiation patterns. hPSC micropatterns are specified by the geometries of the cell stencil through-holes, which physically confine the locations where the underlying extracellular matrix and hPSCs can access and attach to the substrate. This confers the unique capability of stencil micropatterning to work with a variety of culture substrates and extracellular matrices for optimal hPSC culture. We present the detailed steps of stencil micropatterning to successfully generate hPSC micropatterns, which can be used to investigate how spatial polarization of cell adhesion results in cell fate heterogeneity. PMID:27032943

  5. The binding, transport and fate of aluminium in biological cells.

    PubMed

    Exley, Christopher; Mold, Matthew J

    2015-04-01

    Aluminium is the most abundant metal in the Earth's crust and yet, paradoxically, it has no known biological function. Aluminium is biochemically reactive, it is simply that it is not required for any essential process in extant biota. There is evidence neither of element-specific nor evolutionarily conserved aluminium biochemistry. This means that there are no ligands or chaperones which are specific to its transport, there are no transporters or channels to selectively facilitate its passage across membranes, there are no intracellular storage proteins to aid its cellular homeostasis and there are no pathways which evolved to enable the metabolism and excretion of aluminium. Of course, aluminium is found in every compartment of every cell of every organism, from virus through to Man. Herein we have investigated each of the 'silent' pathways and metabolic events which together constitute a form of aluminium homeostasis in biota, identifying and evaluating as far as is possible what is known and, equally importantly, what is unknown about its uptake, transport, storage and excretion.

  6. Engineering Fat Cell Fate to Fight Obesity and Metabolic Diseases.

    PubMed

    Kajimura, Shingo

    2015-01-01

    All mammals harbor two types of adipose tissues that serve distinct physiological functions: white adipose tissue (WAT) and brown adipose tissue (BAT). WAT functions mainly in the storage of excess energy, while BAT specializes in dissipating energy in the form of heat and functions as a defense against hypothermia and obesity. Since adult humans possess significant amounts of active BAT depots and it's mass inversely correlates with adiposity, BAT plays an important role in human obesity and energy homeostasis.New evidence suggests two types of thermogenic adipocytes with distinct developmental and anatomical features: classical brown adipocytes and beige adipocytes. Classical brown adipocytes are located mainly in dedicated BAT depots of rodents and infants. Beige adipocytes, on the other hand, reside mainly in subcutaneous WAT where they arise postnatally in response to certain external cues, such as chronic cold exposure and long-term treatment with PPAR- agonists, a process often referred to as the "browning" of WAT. Importantly, adult human BAT appears to be mainly composed of beige-like adipocytes, making this cell type an attractive therapeutic target for obesity and obesity-related diseases, such as insulin resistance and type2 diabetes. I will review recent progress in the molecular control of brown and beige adipocyte development and discuss emerging questions.(Presented at the 1912th Meeting, December 21, 2015). PMID:26727580

  7. Engineering Fat Cell Fate to Fight Obesity and Metabolic Diseases.

    PubMed

    Kajimura, Shingo

    2015-01-01

    All mammals harbor two types of adipose tissues that serve distinct physiological functions: white adipose tissue (WAT) and brown adipose tissue (BAT). WAT functions mainly in the storage of excess energy, while BAT specializes in dissipating energy in the form of heat and functions as a defense against hypothermia and obesity. Since adult humans possess significant amounts of active BAT depots and it's mass inversely correlates with adiposity, BAT plays an important role in human obesity and energy homeostasis.New evidence suggests two types of thermogenic adipocytes with distinct developmental and anatomical features: classical brown adipocytes and beige adipocytes. Classical brown adipocytes are located mainly in dedicated BAT depots of rodents and infants. Beige adipocytes, on the other hand, reside mainly in subcutaneous WAT where they arise postnatally in response to certain external cues, such as chronic cold exposure and long-term treatment with PPAR- agonists, a process often referred to as the "browning" of WAT. Importantly, adult human BAT appears to be mainly composed of beige-like adipocytes, making this cell type an attractive therapeutic target for obesity and obesity-related diseases, such as insulin resistance and type2 diabetes. I will review recent progress in the molecular control of brown and beige adipocyte development and discuss emerging questions.(Presented at the 1912th Meeting, December 21, 2015).

  8. Ventricular cell fate can be specified until the onset of myocardial differentiation

    PubMed Central

    Caporilli, Simona; Latinkic, Branko V.

    2016-01-01

    The mechanisms that govern specification of various cell types that constitute vertebrate heart are not fully understood. Whilst most studies of heart development have utilised the mouse embryo, we have used an alternative model, embryos of the frog Xenopus laevis, which permits direct experimental manipulation of a non-essential heart. We show that in this model pluripotent animal cap explants injected with cardiogenic factor GATA4 mRNA express pan-myocardial as well as ventricular and proepicardial markers. We found that cardiac cell fate diversification, as assessed by ventricular and proepicardial markers, critically depends on tissue integrity, as it is disrupted by dissociation but can be fully restored by inhibition of the BMP pathway and partially by Dkk-1. Ventricular and proepicardial cell fates can also be restored in reaggregated GATA4-expressing cells upon transplantation into a host embryo. The competence of the host embryo to induce ventricular and proepicardial markers gradually decreases with the age of the transplant and is lost by the onset of myocardial differentiation at the late tailbud stage (st. 28). The influence of the host on the transplant was not limited to diversification of cardiac cell fates, but also included induction of growth and rhythmic beating, resulting in generation of a secondary heart-like structure. Our results additionally show that efficient generation of secondary heart requires normal axial patterning of the host embryo. Furthermore, secondary hearts can be induced in a wide range of locations within the host, arguing that the host embryo provides a permissive environment for development of cardiac patterning, growth and physiological maturation. Our results have implications for a major goal of cardiac regenerative medicine, differentiation of ventricular myocardium. PMID:26776863

  9. In Vivo Fate Imaging of Intracerebral Stem Cell Grafts in Mouse Brain

    PubMed Central

    Nelles, Melanie; Beyrau, Andreas; Hoehn, Mathias

    2015-01-01

    We generated transgenic human neural stem cells (hNSCs) stably expressing the reporter genes Luciferase for bioluminescence imaging (BLI) and GFP for fluorescence imaging, for multimodal imaging investigations. These transgenic hNSCs were further labeled with a clinically approved perfluoropolyether to perform parallel 19F MRI studies. In vitro validation demonstrated normal cell proliferation and differentiation of the transgenic and additionally labeled hNSCs, closely the same as the wild type cell line, making them suitable for in vivo application. Labeled and unlabeled transgenic hNSCs were implanted into the striatum of mouse brain. The time profile of their cell fate after intracerebral grafting was monitored during nine days following implantation with our multimodal imaging approach, assessing both functional and anatomical condition. The 19F MRI demarcated the graft location and permitted to estimate the cell number in the graft. BLI showed a pronounce cell loss during this monitoring period, indicated by the decrease of the viability signal. The in vivo obtained cell fate results were further validated and confirmed by immunohistochemistry. We could show that the surviving cells of the graft continued to differentiate into early neurons, while the severe cell loss could be explained by an inflammatory reaction to the graft, showing the graft being surrounded by activated microglia and macrophages. These results are different from earlier cell survival studies of our group where we had implanted the identical cells into the same mouse strain but in the cortex and not in the striatum. The cortical transplanted cells did not show any loss in viability but only pronounced and continuous neuronal differentiation. PMID:26641453

  10. Antagonistic control of cell fates by JNK and p38-MAPK signaling.

    PubMed

    Wada, T; Stepniak, E; Hui, L; Leibbrandt, A; Katada, T; Nishina, H; Wagner, E F; Penninger, J M

    2008-01-01

    During the development and organogenesis of all multicellular organisms, cell fate decisions determine whether cells undergo proliferation, differentiation, or aging. Two independent stress kinase signaling pathways, p38-MAPK, and JNKs, have evolved that relay developmental and environmental cues to determine cell responses. Although multiple stimuli can activate these two stress kinase pathways, the functional interactions and molecular cross-talks between these common second signaling cascades are poorly elucidated. Here we report that JNK and p38-MAPK pathways antagonistically control cellular senescence, oncogenic transformation, and proliferation in primary mouse embryonic fibroblasts (MEFs). Similarly, genetic inactivation of the JNK pathway results in impaired proliferation of fetal hepatoblasts in vitro and defective adult liver regeneration in vivo, which is rescued by inhibition of the p38-MAPK pathway. Thus, the balance between the two stress-signaling pathways, MKK7-JNK and MKK3/6-p38-MAPK, determines cell fate and links environmental and developmental stress to cell cycle arrest, senescence, oncogenic transformation, and adult tissue regeneration. PMID:17762881

  11. Ontogeny of embryogenic callus in Medicago truncatula: the fate of the pluripotent and totipotent stem cells

    PubMed Central

    Wang, Xin-Ding; Nolan, Kim E.; Irwanto, Rina R.; Sheahan, Michael B.; Rose, Ray J.

    2011-01-01

    Background and Aims Understanding the fate and dynamics of cells during callus formation is essential to understanding totipotency and the mechanisms of somatic embryogenesis. Here, the fate of leaf explant cells during the development of embryogenic callus was investigated in the model legume Medicago truncatula. Methods Callus development was examined from cultured leaf explants of the highly regenerable genotype Jemalong 2HA (2HA) and from mesophyll protoplasts of 2HA and wild-type Jemalong. Callus development was studied by histology, manipulation of the culture system, detection of early production of reactive oxygen species and visualization of SERK1 (SOMATIC EMBRYO RECEPTOR KINASE1) gene expression. Key Results Callus formation in leaf explants initiates at the cut surface and within veins of the explant. The ontogeny of callus development is dominated by the division and differentiation of cells derived from pluripotent procambial cells and from dedifferentiated mesophyll cells. Procambium-derived cells differentiated into vascular tissue and rarely formed somatic embryos, whereas dedifferentiated mesophyll cells were competent to form somatic embryos. Interestingly, explants incubated adaxial-side down had substantially less cell proliferation associated with veins yet produced similar numbers of somatic embryos to explants incubated abaxial-side down. Somatic embryos mostly formed on the explant surface originally in contact with the medium, while in protoplast microcalli, somatic embryos only fully developed once at the surface of the callus. Mesophyll protoplasts of 2HA formed embryogenic callus while Jemalong mesophyll protoplasts produced callus rich in vasculature. Conclusions The ontogeny of embryogenic callus in M. truncatula relates to explant orientation and is driven by the dynamics of pluripotent procambial cells, which proliferate and differentiate into vasculature. The ontogeny is also related to de-differentiated mesophyll cells that acquire

  12. Fate of ingested fluids: factors affecting gastric emptying and intestinal absorption of beverages in humans.

    PubMed

    Leiper, John B

    2015-09-01

    The volume of fluid ingested for rehydration is essential in determining the restoration of euhydration because it must be in excess of the water lost since the individual was last euhydrated. The formulation of any ingested beverage is also important as this affects the rate at which the fluid is emptied from the stomach, absorbed in the small intestine, and hence assimilated into the body water pool. This review highlights the essential role of the gastrointestinal tract in the maintenance of hydration status.

  13. Duel of the fates: the role of transcriptional circuits and noise in CD4+ cells.

    PubMed

    Hebenstreit, Daniel; Deonarine, Andrew; Babu, M Madan; Teichmann, Sarah A

    2012-06-01

    CD4+ T cells play key roles in orchestrating adaptive immune responses, and are a popular model for mammalian cell differentiation. While immune regulation would seem to require exactly adjusted mRNA and protein expression levels of key factors, there is little evidence that this is strictly the case. Stochastic gene expression and plasticity of cell types contrast the apparent need for precision. Recent work has provided insight into the magnitude of molecular noise, as well as the relationship between noise, transcriptional circuits and epigenetic modifications in a variety of cell types. These processes and their interplay will also govern gene expression patterns in the different CD4+ cell types, and the determination of their cellular fates. PMID:22498241

  14. The Hippo pathway member YAP enhances human neural crest cell fate and migration

    PubMed Central

    Hindley, Christopher J.; Condurat, Alexandra Larisa; Menon, Vishal; Thomas, Ria; Azmitia, Luis M.; Davis, Jason A.; Pruszak, Jan

    2016-01-01

    The Hippo/YAP pathway serves as a major integrator of cell surface-mediated signals and regulates key processes during development and tumorigenesis. The neural crest is an embryonic tissue known to respond to multiple environmental cues in order to acquire appropriate cell fate and migration properties. Using multiple in vitro models of human neural development (pluripotent stem cell-derived neural stem cells; LUHMES, NTERA2 and SH-SY5Y cell lines), we investigated the role of Hippo/YAP signaling in neural differentiation and neural crest development. We report that the activity of YAP promotes an early neural crest phenotype and migration, and provide the first evidence for an interaction between Hippo/YAP and retinoic acid signaling in this system. PMID:26980066

  15. Early perturbation in mitochondria redox homeostasis in response to environmental stress predicts cell fate in diatoms

    PubMed Central

    van Creveld, Shiri Graff; Rosenwasser, Shilo; Schatz, Daniella; Koren, Ilan; Vardi, Assaf

    2015-01-01

    Diatoms are ubiquitous marine photosynthetic eukaryotes that are responsible for about 20% of global photosynthesis. Nevertheless, little is known about the redox-based mechanisms that mediate diatom sensing and acclimation to environmental stress. Here we used a redox-sensitive green fluorescent protein sensor targeted to various subcellular organelles in the marine diatom Phaeodactylum tricornutum, to map the spatial and temporal oxidation patterns in response to environmental stresses. Specific organelle oxidation patterns were found in response to various stress conditions such as oxidative stress, nutrient limitation and exposure to diatom-derived infochemicals. We found a strong correlation between the mitochondrial glutathione (GSH) redox potential (EGSH) and subsequent induction of cell death in response to the diatom-derived unsaturated aldehyde 2E,4E/Z-decadienal (DD), and a volatile halocarbon (BrCN) that mediate trophic-level interactions in marine diatoms. Induction of cell death in response to DD was mediated by oxidation of mitochondrial EGSH and was reversible by application of GSH only within a narrow time frame. We found that cell fate can be accurately predicted by a distinct life-death threshold of mitochondrial EGSH (−335 mV). We propose that compartmentalized redox-based signaling can integrate the input of diverse environmental cues and will determine cell fate decisions as part of algal acclimation to stress conditions. PMID:25083933

  16. Neuronal cell fate diversification controlled by sub-temporal action of Kruppel

    PubMed Central

    Stratmann, Johannes; Gabilondo, Hugo; Benito-Sipos, Jonathan; Thor, Stefan

    2016-01-01

    During Drosophila embryonic nervous system development, neuroblasts express a programmed cascade of five temporal transcription factors that govern the identity of cells generated at different time-points. However, these five temporal genes fall short of accounting for the many distinct cell types generated in large lineages. Here, we find that the late temporal gene castor sub-divides its large window in neuroblast 5–6 by simultaneously activating two cell fate determination cascades and a sub-temporal regulatory program. The sub-temporal program acts both upon itself and upon the determination cascades to diversify the castor window. Surprisingly, the early temporal gene Kruppel acts as one of the sub-temporal genes within the late castor window. Intriguingly, while the temporal gene castor activates the two determination cascades and the sub-temporal program, spatial cues controlling cell fate in the latter part of the 5–6 lineage exclusively act upon the determination cascades. DOI: http://dx.doi.org/10.7554/eLife.19311.001 PMID:27740908

  17. Dissection of a Krox20 positive feedback loop driving cell fate choices in hindbrain patterning

    PubMed Central

    Bouchoucha, Yassine X; Reingruber, Jürgen; Labalette, Charlotte; Wassef, Michel A; Thierion, Elodie; Desmarquet-Trin Dinh, Carole; Holcman, David; Gilardi-Hebenstreit, Pascale; Charnay, Patrick

    2013-01-01

    Although feedback loops are essential in development, their molecular implementation and precise functions remain elusive. Using enhancer knockout in mice, we demonstrate that a direct, positive autoregulatory loop amplifies and maintains the expression of Krox20, a transcription factor governing vertebrate hindbrain segmentation. By combining quantitative data collected in the zebrafish with biophysical modelling that accounts for the intrinsic stochastic molecular dynamics, we dissect the loop at the molecular level. We find that it underpins a bistable switch that turns a transient input signal into cell fate commitment, as we observe in single cell analyses. The stochasticity of the activation process leads to a graded input–output response until saturation is reached. Consequently, the duration and strength of the input signal controls the size of the hindbrain segments by modulating the distribution between the two cell fates. Moreover, segment formation is buffered from severe variations in input level. Finally, the progressive extinction of Krox20 expression involves a destabilization of the loop by repressor molecules. These mechanisms are of general significance for cell type specification and tissue patterning. PMID:24061538

  18. Ectopic expression of Cvh (Chicken Vasa homologue) mediates the reprogramming of chicken embryonic stem cells to a germ cell fate.

    PubMed

    Lavial, Fabrice; Acloque, Hervé; Bachelard, Elodie; Nieto, M Angela; Samarut, Jacques; Pain, Bertrand

    2009-06-01

    When they are derived from blastodermal cells of the pre-primitive streak in vitro, the pluripotency of Chicken Embryonic Stem Cells (cESC) can be controlled by the cPouV and Nanog genes. These cESC can differentiate into derivatives of the three germ layers both in vitro and in vivo, but they only weakly colonize the gonads of host embryos. By contrast, non-cultured blastodermal cells and long-term cultured chicken primordial germ cells maintain full germline competence. This restriction in the germline potential of the cESC may result from either early germline determination in the donor embryos or it may occur as a result of in vitro culture. We are interested in understanding the genetic determinants of germline programming. The RNA binding protein Cvh (Chicken Vasa Homologue) is considered as one such determinant, although its role in germ cell physiology is still unclear. Here we show that the exogenous expression of Cvh, combined with appropriate culture conditions, induces cESC reprogramming towards a germ cell fate. Indeed, these cells express the Dazl, Tudor and Sycp3 germline markers, and they display improved germline colonization and adopt a germ cell fate when injected into recipient embryos. Thus, our results demonstrate that Vasa can drive ES cell differentiation towards the germ cell lineage, both in vitro and in vivo.

  19. Cell fate after mitotic arrest in different tumor cells is determined by the balance between slippage and apoptotic threshold

    SciTech Connect

    Galán-Malo, Patricia; Vela, Laura; Gonzalo, Oscar; Calvo-Sanjuán, Rubén; Gracia-Fleta, Lucía; Naval, Javier; Marzo, Isabel

    2012-02-01

    Microtubule poisons and other anti-mitotic drugs induce tumor death but the molecular events linking mitotic arrest to cell death are still not fully understood. We have analyzed cell fate after mitotic arrest produced by the microtubule-destabilizing drug vincristine in a panel of human tumor cell lines showing different response to vincristine. In Jurkat, RPMI 8226 and HeLa cells, apoptosis was triggered shortly after vincristine-induced mitotic arrest. However, A549 cells, which express a great amount of Bcl-x{sub L} and undetectable amounts of Bak, underwent mitotic slippage prior to cell death. However, when Bcl-x{sub L} gene was silenced in A549 cells, vincristine induced apoptosis during mitotic arrest. Another different behavior was found in MiaPaca2 cells, where vincristine caused death by mitotic catastrophe that switched to apoptosis when cyclin B1 degradation was prevented by proteasome inhibition. Overexpression of Bcl-x{sub L} or silencing Bax and Bak expression delayed the onset of apoptosis in Jurkat and RPMI 8226 cells, enabling mitotic slippage and endoreduplication. In HeLa cells, overexpression of Bcl-x{sub L} switched cell death from apoptosis to mitotic catastrophe. Mcl-1 offered limited protection to vincristine-induced cell death and Mcl-1 degradation was not essential for vincristine-induced death. All these results, taken together, indicate that the Bcl-x{sub L}/Bak ratio and the ability to degrade cyclin B1 determine cell fate after mitotic arrest in the different tumor cell types. Highlights: ► Vincristine induces cell death by apoptosis or mitotic catastrophe. ► Apoptosis-proficient cells die by apoptosis during mitosis upon vincristine treatment. ► p53wt apoptosis-deficient cells undergo apoptosis from a G1-like tetraploid state. ► p53mt apoptosis-deficient cells can survive and divide giving rise to 8N cells.

  20. p53 Requires the Stress Sensor USF1 to Direct Appropriate Cell Fate Decision

    PubMed Central

    Bouafia, Amine; Corre, Sébastien; Gilot, David; Mouchet, Nicolas; Prince, Sharon; Galibert, Marie-Dominique

    2014-01-01

    Genomic instability is a major hallmark of cancer. To maintain genomic integrity, cells are equipped with dedicated sensors to monitor DNA repair or to force damaged cells into death programs. The tumor suppressor p53 is central in this process. Here, we report that the ubiquitous transcription factor Upstream Stimulatory factor 1 (USF1) coordinates p53 function in making proper cell fate decisions. USF1 stabilizes the p53 protein and promotes a transient cell cycle arrest, in the presence of DNA damage. Thus, cell proliferation is maintained inappropriately in Usf1 KO mice and in USF1-deficient melanoma cells challenged by genotoxic stress. We further demonstrate that the loss of USF1 compromises p53 stability by enhancing p53-MDM2 complex formation and MDM2-mediated degradation of p53. In USF1-deficient cells, the level of p53 can be restored by the re-expression of full-length USF1 protein similarly to what is observed using Nutlin-3, a specific inhibitor that prevents p53-MDM2 interaction. Consistent with a new function for USF1, a USF1 truncated protein lacking its DNA-binding and transactivation domains can also restore the induction and activity of p53. These findings establish that p53 function requires the ubiquitous stress sensor USF1 for appropriate cell fate decisions in response to DNA-damage. They underscore the new role of USF1 and give new clues of how p53 loss of function can occur in any cell type. Finally, these findings are of clinical relevance because they provide new therapeutic prospects in stabilizing and reactivating the p53 pathway. PMID:24831529

  1. Multifunctionality of PIWI proteins in control of germline stem cell fate.

    PubMed

    Yakushev, E Y; Sokolova, O A; Gvozdev, V A; Klenov, M S

    2013-06-01

    PIWI proteins interacting with specific type of small RNAs (piRNAs) repress transposable elements in animals. Besides, they have been shown to participate in various cellular processes: in the regulation of heterochromatin formation including telomere structures, in the control of translation and the cell cycle, and in DNA rearrangements. PIWI proteins were first identified by their roles in the self-renewal of germline stem cells. PIWI protein functions are not limited to gonadogenesis, but the role in determining the fate of stem cells is their specific feature conserved throughout the evolution of animals. Molecular mechanisms underlying these processes are far from being understood. This review focuses on the role of PIWI proteins in the control of maintenance and proliferation of germinal stem cells and its relation to the known function of PIWI in transposon repression. PMID:23980885

  2. A twist of fate: How a meiotic protein is providing new perspectives on germ cell development.

    PubMed

    Mainpal, Rana; Yanowitz, Judith L

    2016-01-01

    The molecular pathways that govern how germ line fate is acquired is an area of intense investigation that has major implications for the development of assisted reproductive technologies, infertility interventions, and treatment of germ cell cancers. Transcriptional repression has emerged as a primary mechanism to ensure suppression of somatic growth programs in primordial germ cells. In this commentary, we address how xnd-1 illuminates our understanding of transcriptional repression and how it is coordinated with the germ cell differentiation program. We recently identified xnd-1 as a novel, early determinant of germ cell fates in Caenorhabditis elegans. Our study revealed that XND-1 is maternally deposited into early embryos where it is selectively enriched in the germ lineage and then exclusively found on chromatin in the germ lineage throughout development and into adulthood when it dissociates from chromosomes in late pachytene. This localization is consistent with a range of interesting germ cell defects that suggest xnd-1 is a pivotal determinant of germ cell characteristics. Loss of xnd-1 results in a unique "one PGC (primordial germ cell)" phenotype due to G2 cell cycle arrest of the germline precursor blastomere, P4, which predisposes the animal and its progeny for reduced fecundity. The sterility in xnd-1 mutants is correlated with an increase in the transcriptional activation-associated histone modification, dimethylation of histone H3 lysine 4 (H3K4me2), and aberrant expression of somatic transgenes but overlapping roles with nos-2 and nos-1 suggest that transcriptional repression is achieved by multiple redundant mechanisms. PMID:27383565

  3. p53-regulated autophagy is controlled by glycolysis and determines cell fate

    PubMed Central

    Duan, Lei; Perez, Ricardo E.; Davaadelger, Batzaya; Dedkova, Elena N.; Blatter, Lothar A.; Maki, Carl G.

    2015-01-01

    The tumor suppressor p53 regulates downstream targets that determine cell fate. Canonical p53 functions include inducing apoptosis, growth arrest, and senescence. Non-canonical p53 functions include its ability to promote or inhibit autophagy and its ability to regulate metabolism. The extent to which autophagy and/or metabolic regulation determines cell fate by p53 is unclear. To address this, we compared cells resistant or sensitive to apoptosis by the p53 activator Nutlin-3a. In resistant cells, glycolysis was maintained upon Nutlin-3a treatment, and activated p53 promoted prosurvival autophagy. In contrast, in apoptosis sensitive cells activated p53 increased superoxide levels and inhibited glycolysis through repression of glycolytic pathway genes. Glycolysis inhibition and increased superoxide inhibited autophagy by repressing ATG genes essential for autophagic vesicle maturation. Inhibiting glycolysis increased superoxide and blocked autophagy in apoptosis-resistant cells, causing p62-dependent caspase-8 activation. Finally, treatment with 2-DG or the autophagy inhibitors chloroquine or bafilomycin A1 sensitized resistant cells to Nutlin-3a-induced apoptosis. Together, these findings reveal novel links between glycolysis and autophagy that determine apoptosis-sensitivity in response to p53. Specifically, the findings indicate 1) that glycolysis plays an essential role in autophagy by limiting superoxide levels and maintaining expression of ATG genes required for autophagic vesicle maturation, 2) that p53 can promote or inhibit autophagy depending on the status of glycolysis, and 3) that inhibiting protective autophagy can expand the breadth of cells susceptible to Nutlin-3a induced apoptosis. PMID:26337205

  4. Bone morphogenetic protein 2 stimulates endochondral ossification by regulating periosteal cell fate during bone repair

    PubMed Central

    Yu, Yan Yiu; Lieu, Shirley; Lu, Chuanyong; Colnot, Céline

    2010-01-01

    Bone repair depends on the coordinated action of numerous growth factors and cytokines to stimulate new skeletal tissue formation. Among all the growth factors involved in bone repair, Bone Morphogenetic Proteins (BMPs) are the only molecules now used therapeutically to enhance healing. Although BMPs are known as strong bone inducers, their role in initiating skeletal repair is not entirely elucidated. The aim of this study was to define the role of BMP2 during the early stages of bone regeneration and more specifically in regulating the fate of skeletal progenitors. During healing of non-stabilized fractures via endochondral ossification, exogenous BMP2 increased the deposition and resorption of cartilage and bone, which was correlated with a stimulation of osteoclastogenesis but not angiogenesis in the early phase of repair. During healing of stabilized fractures, which normally occurs via intramembranous ossification, exogenous BMP2 induced cartilage formation suggesting a role in regulating cell fate decisions. Specifically, the periosteum was found to be a target of exogenous BMP2 as shown by activation of the BMP pathway in this tissue. Using cell lineage analyses, we further show that BMP2 can direct cell differentiation towards the chondrogenic lineage within the periosteum but not the endosteum, indicating that skeletal progenitors within periosteum and endosteum respond differently to BMP signals. In conclusion, BMP2 plays an important role in the early stages of repair by recruiting local sources of skeletal progenitors within periosteum and endosteum and by determining their differentiation towards the chondrogenic and osteogenic lineages. PMID:20348041

  5. Ectodysplasin/NF-κB Promotes Mammary Cell Fate via Wnt/β-catenin Pathway

    PubMed Central

    Voutilainen, Maria; Lönnblad, Darielle; Shirokova, Vera; Elo, Teresa; Rysti, Elisa; Schmidt-Ullrich, Ruth; Schneider, Pascal; Mikkola, Marja L.

    2015-01-01

    Mammary gland development commences during embryogenesis with the establishment of a species typical number of mammary primordia on each flank of the embryo. It is thought that mammary cell fate can only be induced along the mammary line, a narrow region of the ventro-lateral skin running from the axilla to the groin. Ectodysplasin (Eda) is a tumor necrosis factor family ligand that regulates morphogenesis of several ectodermal appendages. We have previously shown that transgenic overexpression of Eda (K14-Eda mice) induces formation of supernumerary mammary placodes along the mammary line. Here, we investigate in more detail the role of Eda and its downstream mediator transcription factor NF-κB in mammary cell fate specification. We report that K14-Eda mice harbor accessory mammary glands also in the neck region indicating wider epidermal cell plasticity that previously appreciated. We show that even though NF-κB is not required for formation of endogenous mammary placodes, it is indispensable for the ability of Eda to induce supernumerary placodes. A genome-wide profiling of Eda-induced genes in mammary buds identified several Wnt pathway components as potential transcriptional targets of Eda. Using an ex vivo culture system, we show that suppression of canonical Wnt signalling leads to a dose-dependent inhibition of supernumerary placodes in K14-Eda tissue explants. PMID:26581094

  6. Ectodysplasin/NF-κB Promotes Mammary Cell Fate via Wnt/β-catenin Pathway.

    PubMed

    Voutilainen, Maria; Lindfors, Päivi H; Trela, Ewelina; Lönnblad, Darielle; Shirokova, Vera; Elo, Teresa; Rysti, Elisa; Schmidt-Ullrich, Ruth; Schneider, Pascal; Mikkola, Marja L

    2015-11-01

    Mammary gland development commences during embryogenesis with the establishment of a species typical number of mammary primordia on each flank of the embryo. It is thought that mammary cell fate can only be induced along the mammary line, a narrow region of the ventro-lateral skin running from the axilla to the groin. Ectodysplasin (Eda) is a tumor necrosis factor family ligand that regulates morphogenesis of several ectodermal appendages. We have previously shown that transgenic overexpression of Eda (K14-Eda mice) induces formation of supernumerary mammary placodes along the mammary line. Here, we investigate in more detail the role of Eda and its downstream mediator transcription factor NF-κB in mammary cell fate specification. We report that K14-Eda mice harbor accessory mammary glands also in the neck region indicating wider epidermal cell plasticity that previously appreciated. We show that even though NF-κB is not required for formation of endogenous mammary placodes, it is indispensable for the ability of Eda to induce supernumerary placodes. A genome-wide profiling of Eda-induced genes in mammary buds identified several Wnt pathway components as potential transcriptional targets of Eda. Using an ex vivo culture system, we show that suppression of canonical Wnt signalling leads to a dose-dependent inhibition of supernumerary placodes in K14-Eda tissue explants. PMID:26581094

  7. Ectodysplasin/NF-κB Promotes Mammary Cell Fate via Wnt/β-catenin Pathway.

    PubMed

    Voutilainen, Maria; Lindfors, Päivi H; Trela, Ewelina; Lönnblad, Darielle; Shirokova, Vera; Elo, Teresa; Rysti, Elisa; Schmidt-Ullrich, Ruth; Schneider, Pascal; Mikkola, Marja L

    2015-11-01

    Mammary gland development commences during embryogenesis with the establishment of a species typical number of mammary primordia on each flank of the embryo. It is thought that mammary cell fate can only be induced along the mammary line, a narrow region of the ventro-lateral skin running from the axilla to the groin. Ectodysplasin (Eda) is a tumor necrosis factor family ligand that regulates morphogenesis of several ectodermal appendages. We have previously shown that transgenic overexpression of Eda (K14-Eda mice) induces formation of supernumerary mammary placodes along the mammary line. Here, we investigate in more detail the role of Eda and its downstream mediator transcription factor NF-κB in mammary cell fate specification. We report that K14-Eda mice harbor accessory mammary glands also in the neck region indicating wider epidermal cell plasticity that previously appreciated. We show that even though NF-κB is not required for formation of endogenous mammary placodes, it is indispensable for the ability of Eda to induce supernumerary placodes. A genome-wide profiling of Eda-induced genes in mammary buds identified several Wnt pathway components as potential transcriptional targets of Eda. Using an ex vivo culture system, we show that suppression of canonical Wnt signalling leads to a dose-dependent inhibition of supernumerary placodes in K14-Eda tissue explants.

  8. SCARECROW-LIKE23 and SCARECROW jointly specify endodermal cell fate but distinctly control SHORT-ROOT movement.

    PubMed

    Long, Yuchen; Goedhart, Joachim; Schneijderberg, Martinus; Terpstra, Inez; Shimotohno, Akie; Bouchet, Benjamin P; Akhmanova, Anna; Gadella, Theodorus W J; Heidstra, Renze; Scheres, Ben; Blilou, Ikram

    2015-11-01

    Intercellular signaling through trafficking of regulatory proteins is a widespread phenomenon in plants and can deliver positional information for the determination of cell fate. In the Arabidopsis root meristem, the cell fate determinant SHORT-ROOT (SHR), a GRAS domain transcription factor, acts as a signaling molecule from the stele to the adjacent layer to specify endodermal cell fate. Upon exiting the stele, SHR activates another GRAS domain transcription factor, SCARCROW (SCR), which, together with several BIRD/INDETERMINATE DOMAIN proteins, restricts movement of SHR to define a single cell layer of endodermis. Here we report that endodermal cell fate also requires the joint activity of both SCR and its closest homologue SCARECROW-LIKE23 (SCL23). We show that SCL23 protein moves with zonation-dependent directionality. Within the meristem, SCL23 exhibits short-ranged movement from ground tissue to vasculature. Away from the meristem, SCL23 displays long-range rootward movement into meristematic vasculature and a bidirectional radial spread, respectively. As a known target of SHR and SCR, SCL23 also interacts with SCR and SHR and can restrict intercellular outspread of SHR without relying on nuclear retention as SCR does. Collectively, our data show that SCL23 is a mobile protein that controls movement of SHR and acts redundantly with SCR to specify endodermal fate in the root meristem.

  9. Stencil Micropatterning of Human Pluripotent Stem Cells for Probing Spatial Organization of Differentiation Fates.

    PubMed

    Sahni, Geetika; Yuan, Jun; Toh, Yi-Chin

    2016-01-01

    Human pluripotent stem cells (hPSCs), including embryonic stem cells and induced pluripotent stem cells, have the intrinsic ability to differentiate into all three germ layers. This makes them an attractive cell source for regenerative medicine and experimental modeling of normal and diseased organogenesis. However, the differentiation of hPSCs in vitro is heterogeneous and spatially disordered. Cell micropatterning technologies potentially offer the means to spatially control stem cell microenvironments and organize the resultant differentiation fates. Micropatterning hPSCs needs to take into account the stringent requirements for hPSC survival and maintenance. Here, we describe stencil micropatterning as a method that is highly compatible with hPSCs. hPSC micropatterns are specified by the geometries of the cell stencil through-holes, which physically confine the locations where hPSCs can access and attach to the underlying extracellular matrix-coated substrate. Due to this mode of operation, there is greater flexibility to use substrates that can adequately support hPSCs as compared to other cell micropatterning methods. We also highlight critical steps for the successful generation of hPSC micropatterns. As an example, we demonstrate that stencil micropatterning of hPSCs can be used to modulate spatial polarization of cell-cell and cell-matrix adhesions, which in turn determines mesoendoderm differentiation patterns. This simple and robust method to micropattern hPSCs widens the prospects of establishing experimental models to investigate tissue organization and patterning during early embryonic development. PMID:27340925

  10. BMP-SHH signaling network controls epithelial stem cell fate via regulation of its niche in the developing tooth.

    PubMed

    Li, Jingyuan; Feng, Jifan; Liu, Yang; Ho, Thach-Vu; Grimes, Weston; Ho, Hoang Anh; Park, Shery; Wang, Songlin; Chai, Yang

    2015-04-20

    During embryogenesis, ectodermal stem cells adopt different fates and form diverse ectodermal organs, such as teeth, hair follicles, mammary glands, and salivary glands. Interestingly, these ectodermal organs differ in their tissue homeostasis, which leads to differential abilities for continuous growth postnatally. Mouse molars lose the ability to grow continuously, whereas incisors retain this ability. In this study, we found that a BMP-Smad4-SHH-Gli1 signaling network may provide a niche supporting transient Sox2+ dental epithelial stem cells in mouse molars. This mechanism also plays a role in continuously growing mouse incisors. The differential fate of epithelial stem cells in mouse molars and incisors is controlled by this BMP/SHH signaling network, which partially accounts for the different postnatal growth potential of molars and incisors. Collectively, our study highlights the importance of crosstalk between two signaling pathways, BMP and SHH, in regulating the fate of epithelial stem cells during organogenesis.

  11. Stealth filaments: polymer chain length and conformation affect the in vivo fate of PEGylated potato virus X

    PubMed Central

    Lee, Karin L.; Shukla, Sourabh; Wu, Mengzhi; Ayat, Nadia R.; El Sanadi, Caroline E.; Wen, Amy M.; Edelbrock, John F.; Pokorski, Jonathan K.; Commandeur, Ulrich; Dubyak, George R.

    2015-01-01

    Nanoparticles hold great promise for delivering medical cargos to cancerous tissues to enhance contrast and sensitivity of imaging agents or to increase specificity and efficacy of therapeutics. A growing body of data suggests that nanoparticle shape, in combination with surface chemistry, affects their in vivo fates, with elongated filaments showing enhanced tumor targeting and tissue penetration, while promoting immune evasion. The synthesis of high aspect ratio filamentous materials at the nanoscale remains challenging using synthetic routes; therefore we turned toward nature’s materials, developing and studying the filamentous structures formed by the plant virus potato virus X (PVX). We recently demonstrated that PVX shows enhanced tumor homing in various preclinical models. Like other nanoparticle systems, the proteinaceous platform is cleared from circulation and tissues by the mononuclear phagocyte system (MPS). To increase bioavailability we set out to develop PEGylated stealth filaments and evaluate the effects of PEG chain length and conformation on pharmacokinetics, biodistribution, as well as potential immune and inflammatory responses. We demonstrate that PEGylation effectively reduces immune recognition while increasing pharmacokinetic profiles. Stealth filaments show biodistribution consistent with MPS clearance mechanisms; the protein:polymer hybrids are cleared from the body indicating biodegradability and biocompatibility. Tissue compatibility is indicated with no apparent inflammatory signaling in vivo. Tailoring PEG chain length and conformation (brush vs. mushroom) allows tuning of the pharmacokinetics, yielding long-circulating stealth filaments for applications in nanomedicine. PMID:25769228

  12. Cell Fate Determination and the Switch from Diffuse Growth to Planar Polarity in Arabidopsis Root Epidermal Cells

    PubMed Central

    Balcerowicz, Daria; Schoenaers, Sébastjen; Vissenberg, Kris

    2015-01-01

    Plant roots fulfill important functions as they serve in water and nutrient uptake, provide anchorage of the plant body in the soil and in some species form the site of symbiotic interactions with soil-living biota. Root hairs, tubular-shaped outgrowths of specific epidermal cells, significantly increase the root’s surface area and aid in these processes. In this review we focus on the molecular mechanisms that determine the hair and non-hair cell fate of epidermal cells and that define the site on the epidermal cell where the root hair will be initiated (=planar polarity determination). In the model plant Arabidopsis, trichoblast and atrichoblast cell fate results from intra- and intercellular position-dependent signaling and from complex feedback loops that ultimately regulate GL2 expressing and non-expressing cells. When epidermal cells reach the end of the root expansion zone, root hair promoting transcription factors dictate the establishment of polarity within epidermal cells followed by the selection of the root hair initiation site at the more basal part of the trichoblast. Molecular players in the abovementioned processes as well as the role of phytohormones are discussed, and open areas for future experiments are identified. PMID:26779192

  13. Twist1 Controls a Cell-Specification Switch Governing Cell Fate Decisions within the Cardiac Neural Crest

    PubMed Central

    Vincentz, Joshua W.; Firulli, Beth A.; Lin, Andrea; Spicer, Douglas B.; Howard, Marthe J.; Firulli, Anthony B.

    2013-01-01

    Neural crest cells are multipotent progenitor cells that can generate both ectodermal cell types, such as neurons, and mesodermal cell types, such as smooth muscle. The mechanisms controlling this cell fate choice are not known. The basic Helix-loop-Helix (bHLH) transcription factor Twist1 is expressed throughout the migratory and post-migratory cardiac neural crest. Twist1 ablation or mutation of the Twist-box causes differentiation of ectopic neuronal cells, which molecularly resemble sympathetic ganglia, in the cardiac outflow tract. Twist1 interacts with the pro-neural factor Sox10 via its Twist-box domain and binds to the Phox2b promoter to repress transcriptional activity. Mesodermal cardiac neural crest trans-differentiation into ectodermal sympathetic ganglia-like neurons is dependent upon Phox2b function. Ectopic Twist1 expression in neural crest precursors disrupts sympathetic neurogenesis. These data demonstrate that Twist1 functions in post-migratory neural crest cells to repress pro-neural factors and thereby regulate cell fate determination between ectodermal and mesodermal lineages. PMID:23555309

  14. Dissecting engineered cell types and enhancing cell fate conversion via CellNet

    PubMed Central

    Morris, Samantha A.; Cahan, Patrick; Li, Hu; Zhao, Anna M.; San Roman, Adrianna K.; Shivdasani, Ramesh A.; Collins, James J.; Daley, George Q.

    2014-01-01

    SUMMARY Engineering clinically relevant cells in vitro holds promise for regenerative medicine, but most protocols fail to faithfully recapitulate target cell properties. To address this, we developed CellNet, a network biology platform that determines whether engineered cells are equivalent to their target tissues, diagnoses aberrant gene regulatory networks, and prioritizes candidate transcriptional regulators to enhance engineered conversions. Using CellNet, we improved B cell to macrophage conversion, transcriptionally and functionally, by knocking down predicted B cell regulators. Analyzing conversion of fibroblasts to induced hepatocytes (iHeps), CellNet revealed an unexpected intestinal program regulated by the master regulator Cdx2. We observed long-term functional engraftment of mouse colon by iHeps, thereby establishing their broader potential as endoderm progenitors and demonstrating direct conversion of fibroblasts into intestinal epithelium. Our studies illustrate how CellNet can be employed to improve direct conversion and to uncover unappreciated properties of engineered cells. PMID:25126792

  15. Surface Position, Not Signaling from Surrounding Maternal Tissues, Specifies Aleurone Epidermal Cell Fate in Maize[OA

    PubMed Central

    Gruis, Darren (Fred); Guo, Hena; Selinger, David; Tian, Qing; Olsen, Odd-Arne

    2006-01-01

    Maize (Zea mays) endosperm consists of an epidermal-like surface layer of aleurone cells, an underlying body of starchy endosperm cells, and a basal layer of transfer cells. To determine whether surrounding maternal tissues perform a role in specifying endosperm cell fates, a maize endosperm organ culture technique was established whereby the developing endosperm is completely removed from surrounding maternal tissues. Using cell type-specific fluorescence markers, we show that aleurone cell fate specification occurs exclusively in response to surface position and does not require specific, continued maternal signal input. The starchy endosperm and aleurone cell fates are freely interchangeable throughout the lifespan of the endosperm, with internalized aleurone cells converting to starchy endosperm cells and with starchy endosperm cells that become positioned at the surface converting to aleurone cells. In contrast to aleurone and starchy endosperm cells, transfer cells fail to develop in in vitro-grown endosperm, supporting earlier indications that maternal tissue interaction is required to fully differentiate this cell type. Several parameters confirm that the maize endosperm organ cultures described herein retain the main developmental features of in planta endosperm, including fidelity of aleurone mutant phenotypes, temporal and spatial control of cell type-specific fluorescent markers, specificity of cell type transcripts, and control of mitotic cell divisions. PMID:16698897

  16. A Multistate Toggle Switch Defines Fungal Cell Fates and Is Regulated by Synergistic Genetic Cues

    PubMed Central

    Anderson, Matthew Z.; Porman, Allison M.; Wang, Na; Mancera, Eugenio; Bennett, Richard J.

    2016-01-01

    Heritable epigenetic changes underlie the ability of cells to differentiate into distinct cell types. Here, we demonstrate that the fungal pathogen Candida tropicalis exhibits multipotency, undergoing stochastic and reversible switching between three cellular states. The three cell states exhibit unique cellular morphologies, growth rates, and global gene expression profiles. Genetic analysis identified six transcription factors that play key roles in regulating cell differentiation. In particular, we show that forced expression of Wor1 or Efg1 transcription factors can be used to manipulate transitions between all three cell states. A model for tristability is proposed in which Wor1 and Efg1 are self-activating but mutually antagonistic transcription factors, thereby forming a symmetrical self-activating toggle switch. We explicitly test this model and show that ectopic expression of WOR1 can induce white-to-hybrid-to-opaque switching, whereas ectopic expression of EFG1 drives switching in the opposite direction, from opaque-to-hybrid-to-white cell states. We also address the stability of induced cell states and demonstrate that stable differentiation events require ectopic gene expression in combination with chromatin-based cues. These studies therefore experimentally test a model of multistate stability and demonstrate that transcriptional circuits act synergistically with chromatin-based changes to drive cell state transitions. We also establish close mechanistic parallels between phenotypic switching in unicellular fungi and cell fate decisions during stem cell reprogramming. PMID:27711197

  17. Human regulatory B cells combine phenotypic and genetic hallmarks with a distinct differentiation fate.

    PubMed

    Lin, Wenyu; Cerny, Daniela; Chua, Edmond; Duan, Kaibo; Yi, June Tai Jing; Shadan, Nurhidaya Binte; Lum, Josephine; Maho-Vaillant, Maud; Zolezzi, Francesca; Wong, Siew Cheng; Larbi, Anis; Fink, Katja; Musette, Philippe; Poidinger, Michael; Calbo, Sébastien

    2014-09-01

    Regulatory B cells (B-reg) produce IL-10 and suppress inflammation in both mice and humans, but limited data on the phenotype and function of these cells have precluded detailed assessment of their contribution to host immunity. In this article, we report that human B-reg cannot be defined based on a phenotype composed of conventional B cell markers, and that IL-10 production can be elicited in both the CD27(+) memory population and naive B cell subset after only a brief stimulation in vitro. We therefore sought to obtain a better definition of IL-10-producing human B-regs using a multiparameter analysis of B cell phenotype, function, and gene expression profile. Exposure to CpG and anti-Ig are the most potent stimuli for IL-10 secretion in human B cells, but microarray analysis revealed that human B cells cotreated with these reagents resulted in only ∼0.7% of genes being differentially expressed between IL-10(+) and IL-10(-) cells. Instead, connectivity map analysis revealed that IL-10-secreting B cells are those undergoing specific differentiation toward a germinal center fate, and we identified a CD11c(+) B cell subset that was not capable of producing IL-10 even under optimal conditions. Our findings will assist in the identification of a broader range of human pro-B-reg populations that may represent novel targets for immunotherapy. PMID:25080484

  18. Removal of damaged proteins during ES cell fate specification requires the proteasome activator PA28

    PubMed Central

    Hernebring, Malin; Fredriksson, Åsa; Liljevald, Maria; Cvijovic, Marija; Norrman, Karin; Wiseman, John; Semb, Henrik; Nyström, Thomas

    2013-01-01

    In embryonic stem cells, removal of oxidatively damaged proteins is triggered upon the first signs of cell fate specification but the underlying mechanism is not known. Here, we report that this phase of differentiation encompasses an unexpected induction of genes encoding the proteasome activator PA28αβ (11S), subunits of the immunoproteasome (20Si), and the 20Si regulator TNFα. This induction is accompanied by assembly of mature PA28-20S(i) proteasomes and elevated proteasome activity. Inhibiting accumulation of PA28α using miRNA counteracted the removal of damaged proteins demonstrating that PA28αβ has a hitherto unidentified role required for resetting the levels of protein damage at the transition from self-renewal to cell differentiation. PMID:23459332

  19. AID-induced remodeling of immunoglobulin genes and B cell fate.

    PubMed

    Laffleur, Brice; Denis-Lagache, Nicolas; Péron, Sophie; Sirac, Christophe; Moreau, Jeanne; Cogné, Michel

    2014-03-15

    Survival and phenotype of normal and malignant B lymphocytes are critically dependent on constitutive signals by the B cell receptor (BCR) for antigen. In addition, either antigen ligation of the BCR or various mitogenic stimuli result in B cell activation and induction of activation-induced deaminase (AID). AID activity can in turn mediate somatic hypermutation (SHM) of immunoglobulin (Ig) V regions and also deeply remodel the Ig heavy chain locus through class switch recombination (CSR) or locus suicide recombination (LSR). In addition to changes linked to affinity for antigen, modifying the class/isotype (i.e. the structure and function) of the BCR or suddenly deleting BCR expression also modulates the fate of antigen-experienced B cells.

  20. Fate and transport of oil sand process-affected water into the underlying clay till: a field study.

    PubMed

    Abolfazlzadehdoshanbehbazari, Mostafa; Birks, S Jean; Moncur, Michael C; Ulrich, Ania C

    2013-08-01

    The South Tailings Pond (STP) is a ~2300-ha tailing pond operated by Suncor Energy Inc. that has received oil sand process-affected (PA) water and mature fine tailings since 2006. The STP is underlain by a clay till, which is in turn underlain by the Wood Creek Sand Channel (WCSC). The sandy deposits of the WCSC provide greater geotechnical stability but could act as a potential flow pathway for PA water to migrate off site and into the Athabasca River. Preliminary modeling of the STP suggests that PA water from the pond will infiltrate into the underlying sand channel, but the extent and development of this impact is still poorly understood. Suncor Energy Inc. built interception wells and a cut-off-wall to control any potential seepage. Here we present the results of an investigation of the fate and transport of PA water in clay till underlying a 10 m × 10 m infiltration pond that was constructed on the southeastern portion of the STP. The geochemistry of pore water in the till underlying the infiltration pond was determined prior to filling with process-affected water (2008) and two years after the infiltration pond was filled with PA waters (2010). Pore water was analyzed for metals, cations, anions, and isotopes ((2)H and (18)O). The distribution of conservative tracers ((18)O and chloride) indicated migration of the PA waters to approximately 0.9 m, but the migrations of major ions and metals were significantly delayed relative to this depth. Uptake of Na and Mo and release of Ca, Mg, Mn, Ba, and Sr suggest that adsorption and ion exchange reactions are the foremost attenuation processes controlling inorganic solutes transport.

  1. Fate and transport of oil sand process-affected water into the underlying clay till: A field study

    NASA Astrophysics Data System (ADS)

    Abolfazlzadehdoshanbehbazari, Mostafa; Birks, S. Jean; Moncur, Michael C.; Ulrich, Ania C.

    2013-08-01

    The South Tailings Pond (STP) is a ~ 2300-ha tailing pond operated by Suncor Energy Inc. that has received oil sand process-affected (PA) water and mature fine tailings since 2006. The STP is underlain by a clay till, which is in turn underlain by the Wood Creek Sand Channel (WCSC). The sandy deposits of the WCSC provide greater geotechnical stability but could act as a potential flow pathway for PA water to migrate off site and into the Athabasca River. Preliminary modeling of the STP suggests that PA water from the pond will infiltrate into the underlying sand channel, but the extent and development of this impact is still poorly understood. Suncor Energy Inc. built interception wells and a cut-off-wall to control any potential seepage. Here we present the results of an investigation of the fate and transport of PA water in clay till underlying a 10 m × 10 m infiltration pond that was constructed on the southeastern portion of the STP. The geochemistry of pore water in the till underlying the infiltration pond was determined prior to filling with process-affected water (2008) and two years after the infiltration pond was filled with PA waters (2010). Pore water was analyzed for metals, cations, anions, and isotopes (2H and 18O). The distribution of conservative tracers (18O and chloride) indicated migration of the PA waters to approximately 0.9 m, but the migrations of major ions and metals were significantly delayed relative to this depth. Uptake of Na and Mo and release of Ca, Mg, Mn, Ba, and Sr suggest that adsorption and ion exchange reactions are the foremost attenuation processes controlling inorganic solutes transport.

  2. Fate and transport of oil sand process-affected water into the underlying clay till: a field study.

    PubMed

    Abolfazlzadehdoshanbehbazari, Mostafa; Birks, S Jean; Moncur, Michael C; Ulrich, Ania C

    2013-08-01

    The South Tailings Pond (STP) is a ~2300-ha tailing pond operated by Suncor Energy Inc. that has received oil sand process-affected (PA) water and mature fine tailings since 2006. The STP is underlain by a clay till, which is in turn underlain by the Wood Creek Sand Channel (WCSC). The sandy deposits of the WCSC provide greater geotechnical stability but could act as a potential flow pathway for PA water to migrate off site and into the Athabasca River. Preliminary modeling of the STP suggests that PA water from the pond will infiltrate into the underlying sand channel, but the extent and development of this impact is still poorly understood. Suncor Energy Inc. built interception wells and a cut-off-wall to control any potential seepage. Here we present the results of an investigation of the fate and transport of PA water in clay till underlying a 10 m × 10 m infiltration pond that was constructed on the southeastern portion of the STP. The geochemistry of pore water in the till underlying the infiltration pond was determined prior to filling with process-affected water (2008) and two years after the infiltration pond was filled with PA waters (2010). Pore water was analyzed for metals, cations, anions, and isotopes ((2)H and (18)O). The distribution of conservative tracers ((18)O and chloride) indicated migration of the PA waters to approximately 0.9 m, but the migrations of major ions and metals were significantly delayed relative to this depth. Uptake of Na and Mo and release of Ca, Mg, Mn, Ba, and Sr suggest that adsorption and ion exchange reactions are the foremost attenuation processes controlling inorganic solutes transport. PMID:23752067

  3. Oriented cell division affects the global stress and cell packing geometry of a monolayer under stretch.

    PubMed

    Xu, Guang-Kui; Liu, Yang; Zheng, Zhaoliang

    2016-02-01

    Cell division plays a vital role in tissue morphogenesis and homeostasis, and the division plane is crucial for cell fate. For isolated cells, extensive studies show that the orientation of divisions is sensitive to cell shape and the direction of extrinsic mechanical forces. However, it is poorly understood that how the cell divides within a cell monolayer and how the local stress change, due to the division, affects the global stress of epithelial monolayers. Here, we use the vertex dynamics models to investigate the effects of division orientation on the configurations and mechanics of a cell monolayer under stretch. We examine three scenarios of the divisions: dividing along the stretch axis, dividing along the geometric long axis of cells, and dividing at a random angle. It is found that the division along the long cell axis can induce the minimal energy difference, and the global stress of the monolayer after stretch releases more rapidly in this case. Moreover, the long-axis division can result in more random cell orientations and more isotropic cell shapes within the monolayer, comparing with other two cases. This study helps understand the division orientation of cells within a monolayer under mechanical stimuli, and may shed light on linking individual cell's behaviors to the global mechanics and patterns of tissues. PMID:26774292

  4. Oriented cell division affects the global stress and cell packing geometry of a monolayer under stretch.

    PubMed

    Xu, Guang-Kui; Liu, Yang; Zheng, Zhaoliang

    2016-02-01

    Cell division plays a vital role in tissue morphogenesis and homeostasis, and the division plane is crucial for cell fate. For isolated cells, extensive studies show that the orientation of divisions is sensitive to cell shape and the direction of extrinsic mechanical forces. However, it is poorly understood that how the cell divides within a cell monolayer and how the local stress change, due to the division, affects the global stress of epithelial monolayers. Here, we use the vertex dynamics models to investigate the effects of division orientation on the configurations and mechanics of a cell monolayer under stretch. We examine three scenarios of the divisions: dividing along the stretch axis, dividing along the geometric long axis of cells, and dividing at a random angle. It is found that the division along the long cell axis can induce the minimal energy difference, and the global stress of the monolayer after stretch releases more rapidly in this case. Moreover, the long-axis division can result in more random cell orientations and more isotropic cell shapes within the monolayer, comparing with other two cases. This study helps understand the division orientation of cells within a monolayer under mechanical stimuli, and may shed light on linking individual cell's behaviors to the global mechanics and patterns of tissues.

  5. Thickness sensing of hMSCs on collagen gel directs stem cell fate

    SciTech Connect

    Leong, Wen Shing; Tay, Chor Yong; Yu, Haiyang; Li, Ang; Wu, Shu Cheng; Duc, Duong-Hong; Lim, Chwee Teck; Tan, Lay Poh

    2010-10-15

    Research highlights: {yields} hMSCs appeared to sense thin collagen gel (130 {mu}m) with higher effective modulus as compared to thick gel (1440 {mu}m). {yields} Control of collagen gel thickness can modulate cellular behavior, even stem cell fate (neuronal vs. Quiescent). {yields} Distinct cellular behavior of hMSCs on thin and thick collagen gel suggests long range interaction of hMSCs with collagen gel. -- Abstract: Mechanically compliant substrate provides crucial biomechanical cues for multipotent stem cells to regulate cellular fates such as differentiation, proliferation and maintenance of their phenotype. Effective modulus of which cells sense is not only determined by intrinsic mechanical properties of the substrate, but also the thickness of substrate. From our study, it was found that interference from underlying rigid support at hundreds of microns away could induce significant cellular response. Human mesenchymal stem cells (hMSCs) were cultured on compliant biological gel, collagen type I, of different thickness but identical ECM composition and local stiffness. The cells sensed the thin gel (130 {mu}m) as having a higher effective modulus than the thick gel (1440 {mu}m) and this was reflected in their changes in morphology, actin fibers structure, proliferation and tissue specific gene expression. Commitment into neuronal lineage was observed on the thin gel only. Conversely, the thick gel (1440 {mu}m) was found to act like a substrate with lower effective modulus that inhibited actin fiber polymerization. Stem cells on the thick substrate did not express tissue specific genes and remained at their quiescent state. This study highlighted the need to consider not only the local modulus but also the thickness of biopolymer gel coating during modulation of cellular responses.

  6. EHMT1 controls brown adipose cell fate and thermogenesis through the PRDM16 complex.

    PubMed

    Ohno, Haruya; Shinoda, Kosaku; Ohyama, Kana; Sharp, Louis Z; Kajimura, Shingo

    2013-12-01

    Brown adipose tissue (BAT) dissipates chemical energy in the form of heat as a defence against hypothermia and obesity. Current evidence indicates that brown adipocytes arise from Myf5(+) dermotomal precursors through the action of PR domain containing protein 16 (PRDM16) transcriptional complex. However, the enzymatic component of the molecular switch that determines lineage specification of brown adipocytes remains unknown. Here we show that euchromatic histone-lysine N-methyltransferase 1 (EHMT1) is an essential BAT-enriched lysine methyltransferase in the PRDM16 transcriptional complex and controls brown adipose cell fate. Loss of EHMT1 in brown adipocytes causes a severe loss of brown fat characteristics and induces muscle differentiation in vivo through demethylation of histone 3 lysine 9 (H3K9me2 and 3) of the muscle-selective gene promoters. Conversely, EHMT1 expression positively regulates the BAT-selective thermogenic program by stabilizing the PRDM16 protein. Notably, adipose-specific deletion of EHMT1 leads to a marked reduction of BAT-mediated adaptive thermogenesis, obesity and systemic insulin resistance. These data indicate that EHMT1 is an essential enzymatic switch that controls brown adipose cell fate and energy homeostasis.

  7. A BMP regulatory network controls ectodermal cell fate decisions at the neural plate border.

    PubMed

    Reichert, Sabine; Randall, Rebecca A; Hill, Caroline S

    2013-11-01

    During ectodermal patterning the neural crest and preplacodal ectoderm are specified in adjacent domains at the neural plate border. BMP signalling is required for specification of both tissues, but how it is spatially and temporally regulated to achieve this is not understood. Here, using a transgenic zebrafish BMP reporter line in conjunction with double-fluorescent in situ hybridisation, we show that, at the beginning of neurulation, the ventral-to-dorsal gradient of BMP activity evolves into two distinct domains at the neural plate border: one coinciding with the neural crest and the other abutting the epidermis. In between is a region devoid of BMP activity, which is specified as the preplacodal ectoderm. We identify the ligands required for these domains of BMP activity. We show that the BMP-interacting protein Crossveinless 2 is expressed in the BMP activity domains and is under the control of BMP signalling. We establish that Crossveinless 2 functions at this time in a positive-feedback loop to locally enhance BMP activity, and show that it is required for neural crest fate. We further demonstrate that the Distal-less transcription factors Dlx3b and Dlx4b, which are expressed in the preplacodal ectoderm, are required for the expression of a cell-autonomous BMP inhibitor, Bambi-b, which can explain the specific absence of BMP activity in the preplacodal ectoderm. Taken together, our data define a BMP regulatory network that controls cell fate decisions at the neural plate border.

  8. A gene expression atlas of a bicoid-depleted Drosophila embryo reveals early canalization of cell fate

    PubMed Central

    Staller, Max V.; Fowlkes, Charless C.; Bragdon, Meghan D. J.; Wunderlich, Zeba; Estrada, Javier; DePace, Angela H.

    2015-01-01

    In developing embryos, gene regulatory networks drive cells towards discrete terminal fates, a process called canalization. We studied the behavior of the anterior-posterior segmentation network in Drosophila melanogaster embryos by depleting a key maternal input, bicoid (bcd), and measuring gene expression patterns of the network at cellular resolution. This method results in a gene expression atlas containing the levels of mRNA or protein expression of 13 core patterning genes over six time points for every cell of the blastoderm embryo. This is the first cellular resolution dataset of a genetically perturbed Drosophila embryo that captures all cells in 3D. We describe the technical developments required to build this atlas and how the method can be employed and extended by others. We also analyze this novel dataset to characterize the degree and timing of cell fate canalization in the segmentation network. We find that in two layers of this gene regulatory network, following depletion of bcd, individual cells rapidly canalize towards normal cell fates. This result supports the hypothesis that the segmentation network directly canalizes cell fate, rather than an alternative hypothesis whereby cells are initially mis-specified and later eliminated by apoptosis. Our gene expression atlas provides a high resolution picture of a classic perturbation and will enable further computational modeling of canalization and gene regulation in this transcriptional network. PMID:25605785

  9. The WEREWOLF MYB protein directly regulates CAPRICE transcription during cell fate specification in the Arabidopsis root epidermis.

    PubMed

    Ryu, Kook Hui; Kang, Yeon Hee; Park, Young-hwan; Hwang, Ildoo; Schiefelbein, John; Lee, Myeong Min

    2005-11-01

    The Arabidopsis root epidermis is composed of two types of cells, hair cells and non-hair cells, and their fate is determined in a position-dependent manner. WEREWOLF (WER), a R2R3 MYB protein, has been shown genetically to function as a master regulator to control both of the epidermal cell fates. To directly test the proposed role of WER in this system, we examined its subcellular localization and defined its transcriptional activation properties. We show that a WER-GFP fusion protein is functional and accumulates in the nucleus of the N-position cells in the Arabidopsis root epidermis, as expected for a transcriptional regulator. We also find that a modified WER protein with a strong activation domain (WER-VP16) promotes the formation of both epidermal cell types, supporting the view that WER specifies both cell fates. In addition, we used the glucocorticoid receptor (GR) inducible system to show that CPC transcription is regulated directly by WER. Using EMSA, we found two WER-binding sites (WBSs; WBSI and WBSII) in the CPC promoter. WER-WBSI binding was confirmed in vivo using the yeast one-hybrid assay. Binding between the WER protein and both WBSs (WBSI and WBSII), and the importance of the two WBSs in CPC promoter activity were confirmed in Arabidopsis. These results provide experimental support for the proposed role of WER as an activator of gene transcription during the specification of both epidermal cell fates.

  10. Viscoelastic Properties of Differentiating Blood Cells Are Fate- and Function-Dependent

    PubMed Central

    Ekpenyong, Andrew E.; Whyte, Graeme; Chalut, Kevin; Pagliara, Stefano; Lautenschläger, Franziska; Fiddler, Christine; Paschke, Stephan; Keyser, Ulrich F.; Chilvers, Edwin R.; Guck, Jochen

    2012-01-01

    Although cellular mechanical properties are known to alter during stem cell differentiation, understanding of the functional relevance of such alterations is incomplete. Here, we show that during the course of differentiation of human myeloid precursor cells into three different lineages, the cells alter their viscoelastic properties, measured using an optical stretcher, to suit their ultimate fate and function. Myeloid cells circulating in blood have to be advected through constrictions in blood vessels, engendering the need for compliance at short time-scales (cell types have increased short time scale compliance and flow better through microfluidic constrictions. Moreover, all three differentiated cell types reduce their steady-state viscosity by more than 50% and show over 140% relative increase in their ability to migrate through tissue-like pores at long time-scales (>minutes), compared to undifferentiated cells. These findings suggest that reduction in steady-state viscosity is a physiological adaptation for enhanced migration through tissues. Our results indicate that the material properties of cells define their function, can be used as a cell differentiation marker and could serve as target for novel therapies. PMID:23028868

  11. Engineering stem cell fate with biochemical and biomechanical properties of microcarriers.

    PubMed

    Sart, Sébastien; Agathos, Spiros N; Li, Yan

    2013-01-01

    Microcarriers have been widely used for various biotechnology applications because of their high scale-up potential, high reproducibility in regulating cellular behavior, and well-documented compliance with current Good Manufacturing Practices (cGMP). Recently, microcarriers have been emerging as a novel approach for stem cell expansion and differentiation, enabling potential scale-up of stem cell-derived products in large bioreactors. This review summarizes recent advances of using microcarriers in mesenchymal stem cell (MSC) and pluripotent stem cell (PSC) cultures. From the reported data, efficient expansion and differentiation of stem cells on microcarriers rely on their ability to modulate cell shape (i.e. round or spreading) and cell organization (i.e. aggregate size). Nonetheless, current screening of microcarriers remains empirical, and accurate understanding of how stem cells interact with microcarriers still remains unknown. This review suggests that accurate characterization of biochemical and biomechanical properties of microcarriers is required to fully exploit their potential in regulating stem cell fate decision. Due to the variety of microcarriers, such detailed analyses should lead to the rational design of application-specific microcarriers, enabling the exploitation of reproducible effects for large scale biomedical applications. PMID:24124017

  12. Fate of Mammalian Cochlear Hair Cells and Stereocilia after Loss of the Stereocilia

    PubMed Central

    Jia, Shuping; Yang, Shiming; Guo, Weiwei; He, David Z.Z.

    2009-01-01

    Cochlear hair cells transduce mechanical stimuli into electrical activity. The site of hair cell transduction is the hair bundle, an array of stereocilia with different height arranged in a staircase. Tip links connect the apex of each stereocilium to the side of its taller neighbor. The hair bundle and tip links of hair cells are susceptible to acoustic trauma and ototoxic drugs. It has been shown that hair cells in lower vertebrates and in the mammalian vestibular system may survive bundle loss and undergo self-repair of the stereocilia. Our goals were to determine whether cochlear hair cells could survive the trauma and whether the tip link and/or the hair bundle could be regenerated. We simulated the acoustic trauma-induced tip link damage or stereociliary loss by disrupting tip links or ablating the hair bundles in the cultured organ of Corti from neonatal gerbils. Hair-cell fate and stereociliary morphology and function were examined using confocal and scanning electron microscopies and electrophysiology. Most bundleless hair cells survived and developed for about 2 weeks. However, no spontaneous hair-bundle regeneration was observed. When tip links were ruptured, repair of tip links and restoration of mechanotransduction were observed in less than 24 hours. Our study suggests that the dynamic nature of the hair cell's transduction apparatus is retained despite the fact that regeneration of the hair bundle is lost in mammalian cochlear hair cells. PMID:19955380

  13. Numb is not a critical regulator of Notch-mediated cell fate decisions in the developing chick inner ear

    PubMed Central

    Eddison, Mark; Weber, Sara J.; Ariza-McNaughton, Linda; Lewis, Julian; Daudet, Nicolas

    2015-01-01

    The Notch signaling pathway controls differentiation of hair cells and supporting cells in the vertebrate inner ear. Here, we have investigated whether Numb, a known regulator of Notch activity in Drosophila, is involved in this process in the embryonic chick. The chicken homolog of Numb is expressed throughout the otocyst at early stages of development and is concentrated at the basal pole of the cells. It is asymmetrically allocated at some cell divisions, as in Drosophila, suggesting that it could act as a determinant inherited by one of the two daughter cells and favoring adoption of a hair-cell fate. To test the implication of Numb in hair cell fate decisions and the regulation of Notch signaling, we used different methods to overexpress Numb at different stages of inner ear development. We found that sustained or late Numb overexpression does not promote hair cell differentiation, and Numb does not prevent the reception of Notch signaling. Surprisingly, none of the Numb-overexpressing cells differentiated into hair cells, suggesting that high levels of Numb protein could interfere with intracellular processes essential for hair cell survival. However, when Numb was overexpressed early and more transiently during ear development, no effect on hair cell formation was seen. These results suggest that in the inner ear at least, Numb does not significantly repress Notch activity and that its asymmetric distribution in dividing precursor cells does not govern the choice between hair cell and supporting cell fates. PMID:25814931

  14. β-Catenin Signaling Biases Multipotent Lingual Epithelial Progenitors to Differentiate and Acquire Specific Taste Cell Fates.

    PubMed

    Gaillard, Dany; Xu, Mingang; Liu, Fei; Millar, Sarah E; Barlow, Linda A

    2015-05-01

    Continuous taste bud cell renewal is essential to maintain taste function in adults; however, the molecular mechanisms that regulate taste cell turnover are unknown. Using inducible Cre-lox technology, we show that activation of β-catenin signaling in multipotent lingual epithelial progenitors outside of taste buds diverts daughter cells from a general epithelial to a taste bud fate. Moreover, while taste buds comprise 3 morphological types, β-catenin activation drives overproduction of primarily glial-like Type I taste cells in both anterior fungiform (FF) and posterior circumvallate (CV) taste buds, with a small increase in Type II receptor cells for sweet, bitter and umami, but does not alter Type III sour detector cells. Beta-catenin activation in post-mitotic taste bud precursors likewise regulates cell differentiation; forced activation of β-catenin in these Shh+ cells promotes Type I cell fate in both FF and CV taste buds, but likely does so non-cell autonomously. Our data are consistent with a model where β-catenin signaling levels within lingual epithelial progenitors dictate cell fate prior to or during entry of new cells into taste buds; high signaling induces Type I cells, intermediate levels drive Type II cell differentiation, while low levels may drive differentiation of Type III cells.

  15. Unique expression patterns of cell fate molecules delineate sequential stages of dentate gyrus development.

    PubMed

    Pleasure, S J; Collins, A E; Lowenstein, D H

    2000-08-15

    The dentate gyrus of the hippocampus is uniquely organized with a displaced proliferative zone that continues to generate dentate granule cells throughout life. We have analyzed the expression of Notch receptors, Notch ligands, and basic helix-loop-helix (bHLH) genes during dentate gyrus development to determine whether the need to maintain a pool of undifferentiated precursors is reflected in the patterns of expression of these genes. Many of these genes are expressed diffusely throughout the cortical neuroepithelium at embryonic days 16 and 17 in the rat, just preceding the migration of newly born granule cells and dentate precursor cells into the dentate anlage. However, at this time, Mash1, Math3, and Id3 expression are all concentrated in the area that specifically gives rise to granule cells and dentate precursor cells. Two days later, at the time of migration of the first granule cells and dentate precursor cells, cells expressing Mash1 are seen in the migratory route from the subventricular zone to the developing dentate gyrus. Newly born granule cells expressing NeuroD are also present in this migratory pathway. In the first postnatal week, precursor cells expressing Mash1 reside in the dentate hilus, and by the third postnatal week they have largely taken up their final position in the subgranular zone along the hilar side of the dentate granule cell layer. After terminal differentiation, granule cells born in the hilus or the subgranular zone begin to express NeuroD followed by NeuroD2. This study establishes that the expression patterns of bHLH mRNAs evolve during the formation of the dentate gyrus, and the precursor cells resident in the mature dentate gyrus share features with precursor cells found in development. Thus, many of the same mechanisms that are known to regulate cell fate and precursor pool size in other brain regions are likely to be operative in the dentate gyrus at all stages of development.

  16. The neural stem cell fate determinant TRIM32 regulates complex behavioral traits.

    PubMed

    Hillje, Anna-Lena; Beckmann, Elisabeth; Pavlou, Maria A S; Jaeger, Christian; Pacheco, Maria P; Sauter, Thomas; Schwamborn, Jens C; Lewejohann, Lars

    2015-01-01

    In mammals, new neurons are generated throughout the entire lifespan in two restricted areas of the brain, the dentate gyrus (DG) of the hippocampus and the subventricular zone (SVZ)-olfactory bulb (OB) system. In both regions newborn neurons display unique properties that clearly distinguish them from mature neurons. Enhanced excitability and increased synaptic plasticity enables them to add specific properties to information processing by modulating the existing local circuitry of already established mature neurons. Hippocampal neurogenesis has been suggested to play a role in spatial-navigation learning, spatial memory, and spatial pattern separation. Cumulative evidences implicate that adult-born OB neurons contribute to learning processes and odor memory. We recently demonstrated that the cell fate determinant TRIM32 is upregulated in differentiating neuroblasts of the SVZ-OB system in the adult mouse brain. The absence of TRIM32 leads to increased progenitor cell proliferation and less cell death. Both effects accumulate in an overproduction of adult-generated OB neurons. Here, we present novel data from behavioral studies showing that such an enhancement of OB neurogenesis not necessarily leads to increased olfactory performance but in contrast even results in impaired olfactory capabilities. In addition, we show at the cellular level that TRIM32 protein levels increase during differentiation of neural stem cells (NSCs). At the molecular level, several metabolic intermediates that are connected to glycolysis, glycine, or cysteine metabolism are deregulated in TRIM32 knockout mice brain tissue. These metabolomics pathways are directly or indirectly linked to anxiety or depression like behavior. In summary, our study provides comprehensive data on how the impairment of neurogenesis caused by the loss of the cell fate determinant TRIM32 causes a decrease of olfactory performance as well as a deregulation of metabolomic pathways that are linked to mood disorders

  17. Minireview: beta-cell replacement therapy for diabetes in the 21st century: manipulation of cell fate by directed differentiation.

    PubMed

    Yechoor, Vijay; Chan, Lawrence

    2010-08-01

    Pancreatic beta-cell failure underlies type 1 diabetes; it also contributes in an essential way to type 2 diabetes. beta-Cell replacement is an important component of any cure for diabetes. The current options of islet and pancreas transplantation are not satisfactory as definitive forms of therapy. Here, we review strategies for induced de novo pancreatic beta-cell formation, which depend on the targeted differentiation of cells into pancreatic beta-cells. With this objective in mind, one can manipulate the fate of three different types of cells: 1) from terminally differentiated cells, e.g. exocrine pancreatic cells, into beta-cells; 2) from multipotent adult stem cells, e.g. hepatic oval cells, into pancreatic islets; and 3) from pluripotent stem cells, e.g. embryonic stem cells and induced pluripotent stem cells, into beta-cells. We will examine the pros and cons of each strategy as well as the hurdles that must be overcome before these approaches to generate new beta-cells will be ready for clinical application. PMID:20219891

  18. Minireview: beta-cell replacement therapy for diabetes in the 21st century: manipulation of cell fate by directed differentiation.

    PubMed

    Yechoor, Vijay; Chan, Lawrence

    2010-08-01

    Pancreatic beta-cell failure underlies type 1 diabetes; it also contributes in an essential way to type 2 diabetes. beta-Cell replacement is an important component of any cure for diabetes. The current options of islet and pancreas transplantation are not satisfactory as definitive forms of therapy. Here, we review strategies for induced de novo pancreatic beta-cell formation, which depend on the targeted differentiation of cells into pancreatic beta-cells. With this objective in mind, one can manipulate the fate of three different types of cells: 1) from terminally differentiated cells, e.g. exocrine pancreatic cells, into beta-cells; 2) from multipotent adult stem cells, e.g. hepatic oval cells, into pancreatic islets; and 3) from pluripotent stem cells, e.g. embryonic stem cells and induced pluripotent stem cells, into beta-cells. We will examine the pros and cons of each strategy as well as the hurdles that must be overcome before these approaches to generate new beta-cells will be ready for clinical application.

  19. Dynamics and heterogeneity of a fate determinant during transition towards cell differentiation

    DOE PAGES

    Peláez, Nicolás; Gavalda-Miralles, Arnau; Wang, Bao; Navarro, Heliodoro Tejedor; Gudjonson, Herman; Rebay, Ilaria; Dinner, Aaron R.; Katsaggelos, Aggelos K.; Amaral, Luís AN; Carthew, Richard W.

    2015-11-19

    Yan is an ETS-domain transcription factor responsible for maintaining Drosophila eye cells in a multipotent state. Yan is at the core of a regulatory network that determines the time and place in which cells transit from multipotency to one of several differentiated lineages. Using a fluorescent reporter for Yan expression, we observed a biphasic distribution of Yan in multipotent cells, with a rapid inductive phase and slow decay phase. Transitions to various differentiated states occurred over the course of this dynamic process, suggesting that Yan expression level does not strongly determine cell potential. Consistent with this conclusion, perturbing Yan expressionmore » by varying gene dosage had no effect on cell fate transitions. However, we observed that as cells transited to differentiation, Yan expression became highly heterogeneous and this heterogeneity was transient. Signals received via the EGF Receptor were necessary for the transience in Yan noise since genetic loss caused sustained noise. Since these signals are essential for eye cells to differentiate, we suggest that dynamic heterogeneity of Yan is a necessary element of the transition process, and cell states are stabilized through noise reduction.« less

  20. Dynamics and heterogeneity of a fate determinant during transition towards cell differentiation

    PubMed Central

    Peláez, Nicolás; Gavalda-Miralles, Arnau; Wang, Bao; Navarro, Heliodoro Tejedor; Gudjonson, Herman; Rebay, Ilaria; Dinner, Aaron R; Katsaggelos, Aggelos K; Amaral, Luís AN; Carthew, Richard W

    2015-01-01

    Yan is an ETS-domain transcription factor responsible for maintaining Drosophila eye cells in a multipotent state. Yan is at the core of a regulatory network that determines the time and place in which cells transit from multipotency to one of several differentiated lineages. Using a fluorescent reporter for Yan expression, we observed a biphasic distribution of Yan in multipotent cells, with a rapid inductive phase and slow decay phase. Transitions to various differentiated states occurred over the course of this dynamic process, suggesting that Yan expression level does not strongly determine cell potential. Consistent with this conclusion, perturbing Yan expression by varying gene dosage had no effect on cell fate transitions. However, we observed that as cells transited to differentiation, Yan expression became highly heterogeneous and this heterogeneity was transient. Signals received via the EGF Receptor were necessary for the transience in Yan noise since genetic loss caused sustained noise. Since these signals are essential for eye cells to differentiate, we suggest that dynamic heterogeneity of Yan is a necessary element of the transition process, and cell states are stabilized through noise reduction. DOI: http://dx.doi.org/10.7554/eLife.08924.001 PMID:26583752

  1. Cbk1 regulation of the RNA binding protein Ssd1 integrates cell fate with translational control

    PubMed Central

    Jansen, Jaclyn M.; Wanless, Antony G.; Seidel, Christopher W.; Weiss, Eric L.

    2009-01-01

    Summary Spatial control of gene expression, at the level of both transcription and translation, is critical for cellular differentiation [1-4]. In budding yeast, the conserved Ndr/warts kinase Cbk1 localizes to the new daughter cell where it acts as a cell fate determinant. Cbk1 both induces a daughter-specific transcriptional program and promotes morphogenesis in a less well-defined role [5-8]. Cbk1 is essential in cells expressing functional Ssd1, an RNA binding protein of unknown function [9-11]. We show that Cbk1 inhibits Ssd1 in vivo. Loss of this regulation dramatically slows bud expansion, leading to highly aberrant cell wall organization at the site of cell growth. Ssd1 associates with specific mRNAs, a significant number of which encode cell wall remodeling proteins. Translation of these messages is rapidly and specifically suppressed when Cbk1 is inhibited; this suppression requires Ssd1. Transcription of several of these Ssd1-associated mRNAs is also regulated by Cbk1, indicating that the kinase controls both the transcription and translation of daughter-specific mRNAs. This work suggests a novel system by which cells coordinate localized expression of genes involved in processes critical for cell growth and division. PMID:19962308

  2. Expression Levels of Histone Deacetylases Determine the Cell Fate of Hematopoietic Progenitors*

    PubMed Central

    Wada, Taeko; Kikuchi, Jiro; Nishimura, Noriko; Shimizu, Rumi; Kitamura, Toshio; Furukawa, Yusuke

    2009-01-01

    Histone deacetylases (HDACs) are globally implicated in the growth and differentiation of mammalian cells; however, relatively little is known about their specific roles in hematopoiesis. In this study, we investigated the expression of HDACs in human hematopoietic cells and their functions during hematopoiesis. The expression of HDACs was very low in hematopoietic progenitor cells, which was accompanied by histone hyperacetylation. HDACs were detectable in more differentiated progenitors and erythroid precursors but down-regulated in mature myeloid cells especially granulocytes. In contrast, acute myeloid leukemias showed HDAC overexpression and histone hypoacetylation. Transcription of the HDAC1 gene was repressed by CCAAT/enhancer binding proteins during myeloid differentiation, and activated by GATA-1 during erythro-megakaryocytic differentiation. Small interfering RNA-mediated knockdown of HDAC1 enhanced myeloid differentiation in immature hematopoietic cell lines and perturbed erythroid differentiation in progenitor cells. Myeloid but not erythro-megakaryocytic differentiation was blocked in mice transplanted with HDAC1-overexpressing hematopoietic progenitor cells. These findings suggest that HDAC is not merely an auxiliary factor of genetic elements but plays a direct role in the cell fate decision of hematopoietic progenitors. PMID:19736310

  3. Morphogenesis of Drosophila melanogaster macrochaetes: cell fate determination for bristle organ.

    PubMed

    Furman, D P; Bukharina, T A

    2012-01-01

    Formation of specialized spatial structures comprising various cell types is most important in the ontogenesis of multicellular organisms. An example is the D. melanogaster bristle organs. Bristles (micro- and macrochaetes) are external sensory organs, elements of the peripheral nervous system, playing the role of mechanoreceptors. Their comparatively simple organization comprising only four specialized cells and a common origin of these cells make macrochaetes a convenient model for studying cell differentiation. The four cells forming bristle organ result from two successive divisions of a single cell, sensory organ precursor (SOP) cell. The number of macrochaetes on drosophila body corresponds to the number of SOP cells. The morphogenesis of macrochaetes comprises three stages, the first two determining a neural fate of the cells. The third stage is cell specialization into components of the bristle organ-neuron, thecogen, tormogen, and trichogen. Development of each bristle commences from segregation of proneural clusters, of 20-30 cells, from the massif of undifferentiated cells of the wing imaginal disc. At this stage, each cluster cell can potentially become a SOP cell. At the second stage, the only SOP cell and its position are determined within each cluster. Finally, two asymmetric divisions of the SOP cell with subsequent differentiation of the daughter cells gives the bristle organ. Several dozens genes are involved in the control of macrochaete morphogenesis. The main component of this system is the proneural genes of achaete-scute complex (AS-C). An increased content of proneural proteins fundamentally distinguished the cells that will follow the neural developmental pathway from the disc epidermal cells. A local AS-C expression, initiated at specified disc sites by specific transcription factors, determines the number and topology of proneural clusters. The expression of AS-C genes, continuing in the cells of the cluster, increases the difference in

  4. The Methylated DNA Immunoprecipitation [MeDIP] to Investigate the Epigenetic Remodeling in Cell Fate Determination and Cancer Development.

    PubMed

    Masciarelli, Silvia; Bellissimo, Teresa; Iosue, Ilaria; Fazi, Francesco

    2016-01-01

    Epigenetic mechanisms such as DNA methylation, posttranslational modifications of histone proteins, remodeling of nucleosomes, and the expression of noncoding RNAs contribute to the regulation of gene expression for the cell fate determination and tissue development. The disruption of these epigenetic mechanisms, in conjunction with genetic alterations, is a decisive element for cancer development and progression. The cancer phenotype is characterized by global DNA hypomethylation and gene-specific hypermethylation. The methylated DNA immunoprecipitation [MeDIP] is a useful approach currently used to clarify the functional consequences of DNA methylation on cell fate determination and cancer development.

  5. Developmental plasticity, cell fate specification and morphogenesis in the early mouse embryo

    PubMed Central

    Bedzhov, Ivan; Graham, Sarah J. L.; Leung, Chuen Yan; Zernicka-Goetz, Magdalena

    2014-01-01

    A critical point in mammalian development is when the early embryo implants into its mother's uterus. This event has historically been difficult to study due to the fact that it occurs within the maternal tissue and therefore is hidden from view. In this review, we discuss how the mouse embryo is prepared for implantation and the molecular mechanisms involved in directing and coordinating this crucial event. Prior to implantation, the cells of the embryo are specified as precursors of future embryonic and extra-embryonic lineages. These preimplantation cell fate decisions rely on a combination of factors including cell polarity, position and cell–cell signalling and are influenced by the heterogeneity between early embryo cells. At the point of implantation, signalling events between the embryo and mother, and between the embryonic and extraembryonic compartments of the embryo itself, orchestrate a total reorganization of the embryo, coupled with a burst of cell proliferation. New developments in embryo culture and imaging techniques have recently revealed the growth and morphogenesis of the embryo at the time of implantation, leading to a new model for the blastocyst to egg cylinder transition. In this model, pluripotent cells that will give rise to the fetus self-organize into a polarized three-dimensional rosette-like structure that initiates egg cylinder formation. PMID:25349447

  6. OVO-like 1 regulates progenitor cell fate in human trophoblast development

    PubMed Central

    Renaud, Stephen J.; Chakraborty, Damayanti; Mason, Clifford W.; Rumi, M. A. Karim; Vivian, Jay L.; Soares, Michael J.

    2015-01-01

    Epithelial barrier integrity is dependent on progenitor cells that either divide to replenish themselves or differentiate into a specialized epithelium. This paradigm exists in human placenta, where cytotrophoblast cells either propagate or undergo a unique differentiation program: fusion into an overlying syncytiotrophoblast. Syncytiotrophoblast is the primary barrier regulating the exchange of nutrients and gases between maternal and fetal blood and is the principal site for synthesizing hormones vital for human pregnancy. How trophoblast cells regulate their differentiation into a syncytium is not well understood. In this study, we show that the transcription factor OVO-like 1 (OVOL1), a homolog of Drosophila ovo, regulates the transition from progenitor to differentiated trophoblast cells. OVOL1 is expressed in human placenta and was robustly induced following stimulation of trophoblast differentiation. Disruption of OVOL1 abrogated cytotrophoblast fusion and inhibited the expression of a broad set of genes required for trophoblast cell fusion and hormonogenesis. OVOL1 was required to suppress genes that maintain cytotrophoblast cells in a progenitor state, including MYC, ID1, TP63, and ASCL2, and bound specifically to regions upstream of each of these genes. Our results reveal an important function of OVOL1 as a regulator of trophoblast progenitor cell fate during human trophoblast development. PMID:26504231

  7. Pigmentation and sporulation are alternative cell fates in Bacillus pumilus SF214.

    PubMed

    Manzo, Nicola; Di Luccia, Blanda; Isticato, Rachele; D'Apuzzo, Enrica; De Felice, Maurilio; Ricca, Ezio

    2013-01-01

    Bacillus pumilus SF214 is a spore forming bacterium, isolated from a marine sample, able to produce a matrix and a orange-red, water soluble pigment. Pigmentation is strictly regulated and high pigment production was observed during the late stationary growth phase in a minimal medium and at growth temperatures lower than the optimum. Only a subpopulation of stationary phase cells produced the pigment, indicating that the stationary culture contains a heterogeneous cell population and that pigment synthesis is a bimodal phenomenon. The fraction of cells producing the pigment varied in the different growth conditions and occurred only in cells not devoted to sporulation. Only some of the pigmented cells were also able to produce a matrix. Pigment and matrix production in SF214 appear then as two developmental fates both alternative to sporulation. Since the pigment had an essential role in the cell resistance to oxidative stress conditions, we propose that within the heterogeneous population different survival strategies can be followed by the different cells.

  8. TLP-1 is an asymmetric cell fate determinant that responds to Wnt signals and controls male tail tip morphogenesis in C. elegans.

    PubMed

    Zhao, Xiaojun; Yang, Ying; Fitch, David H A; Herman, Michael A

    2002-03-01

    We have isolated mutations defining a new gene, tlp-1, that affect asymmetric cell fates and morphogenesis during the development of the C. elegans tail. tlp-1 mutations cause defects in the specification of asymmetric cell fates in the descendants of the T blast cell, whose polarity is controlled by Wnt signaling and cause abnormal male tail development leading to the formation of a posterior protrusion reminiscent of 'leptoderan', or pointy tailed, nematode species. In wild-type C. elegans males, which have a 'peloderan' or rounded tail, retraction of the tail tip hypodermis involves a temporally ordered set of cell fusions and changes in cell shape that appear to be heterochronically delayed in tlp-1 males, suggesting that subtle changes in these events can bring about evolutionary changes in morphology. tlp-1 encodes a C2H2 zinc-finger protein that is a member of the Sp family of transcription factors. A TLP-1::GFP fusion protein is expressed in the nuclei of many cells during early embryogenesis and then becomes restricted primarily to posterior cells. At hatching, it is expressed in several head neurons, the posterior intestine cells, tail hypodermal cells, the T cells and specific T-cell descendents in a pattern that suggests TLP-1 may be asymmetrically expressed during the divisions of the T cell lineage. Furthermore, the asymmetry of TLP-1 expression and function appears to be controlled by Wnt signals that control T cell polarity. These results suggest that tlp-1 encodes a transcription factor required for cellular asymmetry that functions downstream of Wnt signals that control cell polarity, as well as in cell fusion and patterning in the C. elegans tail.

  9. Forced expression of Hnf1b/Foxa3 promotes hepatic fate of embryonic stem cells.

    PubMed

    Yahoo, Neda; Pournasr, Behshad; Rostamzadeh, Jalal; Hakhamaneshi, Mohammad Saeed; Ebadifar, Asghar; Fathi, Fardin; Baharvand, Hossein

    2016-05-20

    Embryonic stem (ES) cell-derived hepatocytes have the potential to be used for basic research, regenerative medicine, and drug discovery. Recent reports demonstrated that in addition to conventional differentiation inducers such as chemical compounds and cytokines, overexpression of lineage-specific transcription factors could induce ES cells to differentiate to a hepatic fate. Here, we hypothesized that lentivirus-mediated inducible expression of hepatic lineage transcription factors could enhance mouse ES cells to hepatocyte-like cells. We screened the effects of candidate transcription factors Hnf1b, Hnf1a, Hnf4a, Foxa1, Foxa3 and Hex, and determined that the combination of Hnf1b/Foxa3 promoted expression of several hepatic lineage-specific markers and proteins, in addition to glycogen storage, ICG uptake, and secretion of albumin and urea. The differentiated cells were engraftable and expressed albumin when transplanted into a carbon tetrachloride-injured mouse model. These results demonstrated the crucial role of Hnf1b and Foxa3 in hepatogenesis in vitro and provided a valuable tool for the efficient differentiation of HLCs from ES cells. PMID:27107701

  10. Turning the fate of reprogramming cells from retinal disorder to regeneration by Pax6 in newts.

    PubMed

    Casco-Robles, Martin Miguel; Islam, Md Rafiqul; Inami, Wataru; Tanaka, Hibiki Vincent; Kunahong, Ailidana; Yasumuro, Hirofumi; Hanzawa, Shiori; Casco-Robles, Roman Martin; Toyama, Fubito; Maruo, Fumiaki; Chiba, Chikafumi

    2016-01-01

    The newt, a urodele amphibian, has an outstanding ability- even as an adult -to regenerate a functional retina through reprogramming and proliferation of the retinal pigment epithelium (RPE) cells, even though the neural retina is completely removed from the eye by surgery. It remains unknown how the newt invented such a superior mechanism. Here we show that disability of RPE cells to regenerate the retina brings about a symptom of proliferative vitreoretinopathy (PVR), even in the newt. When Pax6, a transcription factor that is re-expressed in reprogramming RPE cells, is knocked down in transgenic juvenile newts, these cells proliferate but eventually give rise to cell aggregates that uniformly express alpha smooth muscle actin, Vimentin and N-cadherin, the markers of myofibroblasts which are a major component of the sub-/epi-retinal membranes in PVR. Our current study demonstrates that Pax6 is an essential factor that directs the fate of reprogramming RPE cells toward the retinal regeneration. The newt may have evolved the ability of retinal regeneration by modifying a mechanism that underlies the RPE-mediated retinal disorders. PMID:27640672

  11. The Fate of a Normal Human Cell Traversed by a Single Charged Particle

    NASA Astrophysics Data System (ADS)

    Fournier, C.; Zahnreich, S.; Kraft, D.; Friedrich, T.; Voss, K.-O.; Durante, M.; Ritter, S.

    2012-09-01

    The long-term ``fate'' of normal human cells after single hits of charged particles is one of the oldest unsolved issues in radiation protection and cellular radiobiology. Using a high-precision heavy-ion microbeam we could target normal human fibroblasts with exactly one or five carbon ions and measured the early cytogenetic damage and the late behaviour using single-cell cloning. Around 70% of the first cycle cells presented visible aberrations in mFISH after a single ion traversal, and about 5% of the cells were still able to form colonies. In one third of selected high-proliferative colonies we observed clonal (radiation-induced) aberrations. Terminal differentiation and markers of senescence (PCNA, p16) in the descendants of cells traversed by one carbon ion occurred earlier than in controls, but no evidence of radiation-induced chromosomal instability was found. We conclude that cells surviving single-ion traversal, often carrying clonal chromosome aberrations, undergo accelerated senescence but maintain chromosomal stability.

  12. The influence of immunosuppressive drugs on neural stem/progenitor cell fate in vitro

    SciTech Connect

    Skardelly, Marco; Glien, Anja; Groba, Claudia; Schlichting, Nadine; Kamprad, Manja; Meixensberger, Juergen; Milosevic, Javorina

    2013-12-10

    In allogenic and xenogenic transplantation, adequate immunosuppression plays a major role in graft survival, especially over the long term. The effect of immunosuppressive drugs on neural stem/progenitor cell fate has not been sufficiently explored. The focus of this study is to systematically investigate the effects of the following four different immunotherapeutic strategies on human neural progenitor cell survival/death, proliferation, metabolic activity, differentiation and migration in vitro: (1) cyclosporine A (CsA), a calcineurin inhibitor; (2) everolimus (RAD001), an mTOR-inhibitor; (3) mycophenolic acid (MPA, mycophenolate), an inhibitor of inosine monophosphate dehydrogenase and (4) prednisolone, a steroid. At the minimum effective concentration (MEC), we found a prominent decrease in hNPCs' proliferative capacity (BrdU incorporation), especially for CsA and MPA, and an alteration of the NAD(P)H-dependent metabolic activity. Cell death rate, neurogenesis, gliogenesis and cell migration remained mostly unaffected under these conditions for all four immunosuppressants, except for apoptotic cell death, which was significantly increased by MPA treatment. - Highlights: • Four immunosuppresants (ISs) were tested in human neural progenitor cells in vitro. • Cyclosporine A and mycophenolic acid showed a prominent anti-proliferative activity • Mycophenolic acid exhibited a significant pro-apoptotic effect. • NAD(P)H-dependent metabolic activity was occasionally induced by ISs. • Neuronal differentiation and migration potential remained unaffected by ISs treatment.

  13. Turning the fate of reprogramming cells from retinal disorder to regeneration by Pax6 in newts

    PubMed Central

    Casco-Robles, Martin Miguel; Islam, Md Rafiqul; Inami, Wataru; Tanaka, Hibiki Vincent; Kunahong, Ailidana; Yasumuro, Hirofumi; Hanzawa, Shiori; Casco-Robles, Roman Martin; Toyama, Fubito; Maruo, Fumiaki; Chiba, Chikafumi

    2016-01-01

    The newt, a urodele amphibian, has an outstanding ability– even as an adult –to regenerate a functional retina through reprogramming and proliferation of the retinal pigment epithelium (RPE) cells, even though the neural retina is completely removed from the eye by surgery. It remains unknown how the newt invented such a superior mechanism. Here we show that disability of RPE cells to regenerate the retina brings about a symptom of proliferative vitreoretinopathy (PVR), even in the newt. When Pax6, a transcription factor that is re-expressed in reprogramming RPE cells, is knocked down in transgenic juvenile newts, these cells proliferate but eventually give rise to cell aggregates that uniformly express alpha smooth muscle actin, Vimentin and N-cadherin, the markers of myofibroblasts which are a major component of the sub-/epi-retinal membranes in PVR. Our current study demonstrates that Pax6 is an essential factor that directs the fate of reprogramming RPE cells toward the retinal regeneration. The newt may have evolved the ability of retinal regeneration by modifying a mechanism that underlies the RPE-mediated retinal disorders. PMID:27640672

  14. Matrix stiffness determines the fate of nucleus pulposus-derived stem cells.

    PubMed

    Navaro, Yosi; Bleich-Kimelman, Nadav; Hazanov, Lena; Mironi-Harpaz, Iris; Shachaf, Yonatan; Garty, Shai; Smith, Yoav; Pelled, Gadi; Gazit, Dan; Seliktar, Dror; Gazit, Zulma

    2015-05-01

    Intervertebral disc (IVD) degeneration and consequent low-back pain present a major medical challenge. Nucleus pulposus-derived stem cells (NP-SCs) may lead to a novel therapy for this severe disease. It was recently shown that survival and function of mature NP cells are regulated in part by tissue stiffness. We hypothesized that modification of matrix stiffness will influence the ability of cultured NP-SCs to proliferate, survive, and differentiate into mature NP cells. NP-SCs were subcultured in three-dimensional matrices of varying degrees of stiffness as measured by the material's shear storage modulus. Cell survival, activity, and rate of differentiation toward the chondrogenic or osteogenic lineage were analyzed. NP-SCs were found to proliferate and differentiate in all matrices, irrespective of matrix stiffness. However, matrices with a low shear storage modulus (G' = 1 kPa) promoted significantly more proliferation and chondrogenic differentiation, whereas matrices with a high modulus (G' = 2 kPa) promoted osteogenic differentiation. Imaging performed via confocal and scanning electron microscopes validated cell survival and highlighted stiffness-dependent cell-matrix interactions. These results underscore the effect of the matrix modulus on the fate of NP-SCs. This research may facilitate elucidation of the complex cross-talk between NP-SCs and their surrounding matrix in healthy as well as pathological conditions.

  15. The fate of a normal human cell traversed by a single charged particle.

    PubMed

    Fournier, C; Zahnreich, S; Kraft, D; Friedrich, T; Voss, K O; Durante, M; Ritter, S

    2012-01-01

    The long-term "fate" of normal human cells after single hits of charged particles is one of the oldest unsolved issues in radiation protection and cellular radiobiology. Using a high-precision heavy-ion microbeam we could target normal human fibroblasts with exactly one or five carbon ions and measured the early cytogenetic damage and the late behaviour using single-cell cloning. Around 70% of the first cycle cells presented visible aberrations in mFISH after a single ion traversal, and about 5% of the cells were still able to form colonies. In one third of selected high-proliferative colonies we observed clonal (radiation-induced) aberrations. Terminal differentiation and markers of senescence (PCNA, p16) in the descendants of cells traversed by one carbon ion occurred earlier than in controls, but no evidence of radiation-induced chromosomal instability was found. We conclude that cells surviving single-ion traversal, often carrying clonal chromosome aberrations, undergo accelerated senescence but maintain chromosomal stability. PMID:22966418

  16. TrkB/BDNF Signaling Regulates Photoreceptor Progenitor Cell Fate Decisions

    PubMed Central

    Turner, Brian A.; Sparrow, Janet; Cai, Bolin; Monroe, Julie; Mikawa, Takashi; Hempstead, Barbara L.

    2008-01-01

    Neurotrophins, via activation of Trk receptor tyrosine kinases, serve as mitogens, survival factors and regulators of arborization during retinal development. Brain-derived neurotrophic factor (BDNF) and TrkB regulate neuronal arborization and survival in late retinal development. However, TrkB is expressed during early retinal developmet where its functions are unclear. To assess TrkB/BDNF actions in the early chick retina, replication-incompetent retroviruses were utilized to over-express a dominant negative truncated form of TrkB (trunc TrkB), or BDNF and effects were assessed at E15. Clones expressing trunc TrkB were smaller than controls, and proliferation and apoptosis assays suggest that decreased clone size correlated with increased cell death when BDNF/TrkB signaling was impaired. Analysis of clonal composition revealed that trunc TrkB over-expression decreased photoreceptor numbers (41%) and increased cell numbers in the middle third of the inner nuclear layer (INL) (23%). Conversely, BDNF over-expression increased photoreceptor numbers (25%) and decreased INL numbers (17%). Photoreceptors over-expressing trunc TrkB demonstrated no increase in apoptosis nor abnormalities in lamination suggesting that TrkB activation is not required for photoreceptor cell survival or migration. These studies suggest that TrkB signaling regulates commitment to and/or differentiation of photoreceptor cells from retinal progenitor cells, identifying a novel role for TrkB/BDNF in regulating cell fate decisions. PMID:17005175

  17. Regional signals in the planarian body guide stem cell fate in the presence of genomic instability.

    PubMed

    Peiris, T Harshani; Ramirez, Daniel; Barghouth, Paul G; Ofoha, Udokanma; Davidian, Devon; Weckerle, Frank; Oviedo, Néstor J

    2016-05-15

    Cellular fate decisions are influenced by their topographical location in the adult body. For instance, tissue repair and neoplastic growth are greater in anterior than in posterior regions of adult animals. However, the molecular underpinnings of these regional differences are unknown. We identified a regional switch in the adult planarian body upon systemic disruption of homologous recombination with RNA-interference of Rad51 Rad51 knockdown increases DNA double-strand breaks (DSBs) throughout the body, but stem cells react differently depending on their location along the anteroposterior axis. In the presence of extensive DSBs, cells in the anterior part of the body resist death, whereas cells in the posterior region undergo apoptosis. Furthermore, we found that proliferation of cells with DNA damage is induced in the presence of brain tissue and that the retinoblastoma pathway enables overproliferation of cells with DSBs while attending to the demands of tissue growth and repair. Our results implicate both autonomous and non-autonomous mechanisms as key mediators of regional cell behavior and cellular transformation in the adult body. PMID:27013241

  18. The Role of Scleraxis in Fate Determination of Mesenchymal Stem Cells for Tenocyte Differentiation

    PubMed Central

    Li, Yonghui; Ramcharan, Melissa; Zhou, Zuping; Leong, Daniel J.; Akinbiyi, Takintope; Majeska, Robert J.; Sun, Hui B.

    2015-01-01

    Mesenchymal stem cells (MSCs) are pluripotent cells that primarily differentiate into osteocytes, chondrocytes, and adipocytes. Recent studies indicate that MSCs can also be induced to generate tenocyte-like cells; moreover, MSCs have been suggested to have great therapeutic potential for tendon pathologies. Yet the precise molecular cascades governing tenogenic differentiation of MSCs remain unclear. We demonstrate scleraxis, a transcription factor critically involved in embryonic tendon development and formation, plays a pivotal role in the fate determination of MSC towards tenocyte differentiation. Using murine C3H10T1/2 pluripotent stem cells as a model system, we show scleraxis is extensively expressed in the early phase of bone morphogenetic protein (BMP)-12-triggered tenocytic differentiation. Once induced, scleraxis directly transactivates tendon lineage-related genes such as tenomodulin and suppresses osteogenic, chondrogenic, and adipogenic capabilities, thus committing C3H10T1/2 cells to differentiate into the specific tenocyte-like lineage, while eliminating plasticity for other lineages. We also reveal that mechanical loading-mediated tenocytic differentiation follows a similar pathway and that BMP-12 and cyclic uniaxial strain act in an additive fashion to augment the maximal response by activating signal transducer Smad8. These results provide critical insights into the determination of multipotent stem cells to the tenocyte lineage induced by both chemical and physical signals. PMID:26289033

  19. Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification

    PubMed Central

    Zdravkovic, Tamara; Nazor, Kristopher L.; Larocque, Nicholas; Gormley, Matthew; Donne, Matthew; Hunkapillar, Nathan; Giritharan, Gnanaratnam; Bernstein, Harold S.; Wei, Grace; Hebrok, Matthias; Zeng, Xianmin; Genbacev, Olga; Mattis, Aras; McMaster, Michael T.; Krtolica, Ana; Valbuena, Diana; Simón, Carlos; Laurent, Louise C.; Loring, Jeanne F.; Fisher, Susan J.

    2015-01-01

    Mechanisms of initial cell fate decisions differ among species. To gain insights into lineage allocation in humans, we derived ten human embryonic stem cell lines (designated UCSFB1-10) from single blastomeres of four 8-cell embryos and one 12-cell embryo from a single couple. Compared with numerous conventional lines from blastocysts, they had unique gene expression and DNA methylation patterns that were, in part, indicative of trophoblast competence. At a transcriptional level, UCSFB lines from different embryos were often more closely related than those from the same embryo. As predicted by the transcriptomic data, immunolocalization of EOMES, T brachyury, GDF15 and active β-catenin revealed differential expression among blastomeres of 8- to 10-cell human embryos. The UCSFB lines formed derivatives of the three germ layers and CDX2-positive progeny, from which we derived the first human trophoblast stem cell line. Our data suggest heterogeneity among early-stage blastomeres and that the UCSFB lines have unique properties, indicative of a more immature state than conventional lines. PMID:26483210

  20. Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification.

    PubMed

    Zdravkovic, Tamara; Nazor, Kristopher L; Larocque, Nicholas; Gormley, Matthew; Donne, Matthew; Hunkapillar, Nathan; Giritharan, Gnanaratnam; Bernstein, Harold S; Wei, Grace; Hebrok, Matthias; Zeng, Xianmin; Genbacev, Olga; Mattis, Aras; McMaster, Michael T; Krtolica, Ana; Valbuena, Diana; Simón, Carlos; Laurent, Louise C; Loring, Jeanne F; Fisher, Susan J

    2015-12-01

    Mechanisms of initial cell fate decisions differ among species. To gain insights into lineage allocation in humans, we derived ten human embryonic stem cell lines (designated UCSFB1-10) from single blastomeres of four 8-cell embryos and one 12-cell embryo from a single couple. Compared with numerous conventional lines from blastocysts, they had unique gene expression and DNA methylation patterns that were, in part, indicative of trophoblast competence. At a transcriptional level, UCSFB lines from different embryos were often more closely related than those from the same embryo. As predicted by the transcriptomic data, immunolocalization of EOMES, T brachyury, GDF15 and active β-catenin revealed differential expression among blastomeres of 8- to 10-cell human embryos. The UCSFB lines formed derivatives of the three germ layers and CDX2-positive progeny, from which we derived the first human trophoblast stem cell line. Our data suggest heterogeneity among early-stage blastomeres and that the UCSFB lines have unique properties, indicative of a more immature state than conventional lines.

  1. Turning the fate of reprogramming cells from retinal disorder to regeneration by Pax6 in newts.

    PubMed

    Casco-Robles, Martin Miguel; Islam, Md Rafiqul; Inami, Wataru; Tanaka, Hibiki Vincent; Kunahong, Ailidana; Yasumuro, Hirofumi; Hanzawa, Shiori; Casco-Robles, Roman Martin; Toyama, Fubito; Maruo, Fumiaki; Chiba, Chikafumi

    2016-09-19

    The newt, a urodele amphibian, has an outstanding ability- even as an adult -to regenerate a functional retina through reprogramming and proliferation of the retinal pigment epithelium (RPE) cells, even though the neural retina is completely removed from the eye by surgery. It remains unknown how the newt invented such a superior mechanism. Here we show that disability of RPE cells to regenerate the retina brings about a symptom of proliferative vitreoretinopathy (PVR), even in the newt. When Pax6, a transcription factor that is re-expressed in reprogramming RPE cells, is knocked down in transgenic juvenile newts, these cells proliferate but eventually give rise to cell aggregates that uniformly express alpha smooth muscle actin, Vimentin and N-cadherin, the markers of myofibroblasts which are a major component of the sub-/epi-retinal membranes in PVR. Our current study demonstrates that Pax6 is an essential factor that directs the fate of reprogramming RPE cells toward the retinal regeneration. The newt may have evolved the ability of retinal regeneration by modifying a mechanism that underlies the RPE-mediated retinal disorders.

  2. Canonical Wnt Signaling is Required for Ophthalmic Trigeminal Placode Cell Fate Determination and Maintenance

    PubMed Central

    Lassiter, Rhonda N.T.; Dude, Carolynn; Reynolds, Stephanie B.; Winters, Nichelle I.; Baker, Clare V.H.; Stark, Michael R.

    2014-01-01

    Cranial placodes are ectodermal regions that contribute extensively to the vertebrate peripheral sensory nervous system. The development of the ophthalmic trigeminal (opV) placode, which gives rise only to sensory neurons of the ophthalmic lobe of the trigeminal ganglion, is a useful model of sensory neuron development. While key differentiation processes have been characterized at the tissue and cellular levels, the signaling pathways governing opV placode development have not. Here, we tested in chick whether the canonical Wnt signaling pathway regulates opV placode development. By introducing a Wnt reporter into embryonic chick head ectoderm, we show that the canonical pathway is active in Pax3+ opV placode cells as, or shortly after, they are induced to express Pax3. Blocking the canonical Wnt pathway resulted in the failure of targeted cells to adopt or maintain an opV fate, as assayed by the expression of various markers including Pax3, FGFR4, Eya2, and the neuronal differentiation markers Islet1, neurofilament and NeuN, although, surprisingly, it led to upregulation of Neurogenin2, both in the opV placode and elsewhere in the ectoderm. Activating the canonical Wnt signaling pathway, however, was not sufficient to induce Pax3, the earliest specific marker of the opV placode. We conclude that canonical Wnt signaling is necessary for normal opV placode development, and propose that other molecular cues are required in addition to Wnt signaling to promote cells toward an opV placode fate. PMID:17604017

  3. Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams

    USGS Publications Warehouse

    Choi, J.; Harvey, J.W.; Conklin, M.H.

    2000-01-01

    The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones. However, most investigators use transport models with just a single storage zone in their modeling studies, which assumes that the effects of multiple storage zones can be lumped together. Our study addressed the following question: Can a single-storage zone model reliably characterize the effects of physical retention and biogeochemical reactions in multiple storage zones? We extended an existing stream transport model with a single storage zone to include a second storage zone. With the extended model we generated 500 data sets representing transport of nonreactive and reactive solutes in stream systems that have two different types of storage zones with variable hydrologic conditions. The one storage zone model was tested by optimizing the lumped storage parameters to achieve a best fit for each of the generated data sets. Multiple storage processes were categorized as possessing I, additive; II, competitive; or III, dominant storage zone characteristics. The classification was based on the goodness of fit of generated data sets, the degree of similarity in mean retention time of the two storage zones, and the relative distributions of exchange flux and storage capacity between the two storage zones. For most cases (> 90%) the one storage zone model described either the effect of the sum of multiple storage processes (category I) or the dominant storage process (category III). Failure of the one storage zone model occurred mainly for category II, that is, when one of the storage zones had a much longer mean retention time (t(s) ratio > 5.0) and when the dominance of

  4. Differential cell fates induced by all-trans retinoic acid-treated HL-60 human leukemia cells.

    PubMed

    Ozeki, Munetaka; Shively, John E

    2008-09-01

    HL-60 human leukemia cells, differentiated into a neutrophil lineage by all-trans retinoic acid (ATRA) treatment, express three members of the carcinoembryonic antigen (CEA) gene family, CEA-related cell adhesion molecule 1 (CEACAM1; CD66a), CEACAM3 (CD66d), and CEACAM6 (CD66c). CD66d is a neutrophil lineage-specific marker, and CD66a and CD66c are found on epithelial and other cells. HL-60 cells continuously treated with ATRA underwent apoptosis, and cells transiently treated for 1 day underwent cell-cycle arrest, entered into senescence, and exhibited reduced apoptosis with CD66-positive cells accounting for the majority of live cells. CD66 antigens were also induced in NB4 leukemic cells upon continuous treatment with ATRA. NB4 cells underwent apoptosis with a higher frequency in transient versus continuous-treated cells (38% vs. 19% at Day 5), in contrast to HL-60 cells that underwent cell-cycle arrest and senescence when transiently treated with ATRA. CD66 antigens were not induced in transient, ATRA-treated NB4 cells compared with HL-60 cells. Cell-cycle arrest in HL-60 cells involved reduction in expression levels of p21, cyclins D and E, while Rb1 exhibited reduction in protein levels without changes in mRNA levels over the time course of ATRA treatment. Analysis of several proapoptotic proteins implicated the activation of calpain and cleavage of Bax in the intrinsic apoptotic pathway, similar to published studies about the apoptosis of neutrophils. CD1d expression was also induced by ATRA in HL-60 cells and ligation with anti-CD1d antibody-induced apoptosis. In contrast, CD1d-positive primary monocytes were protected from spontaneous apoptosis by CD1d ligation. These studies demonstrate distinct cell fates for ATRA-treated HL-60 cells that provide new insights into ATRA-induced cell differentiation.

  5. Prox1 postmitotically defines dentate gyrus cells by specifying granule cell identity over CA3 pyramidal cell fate in the hippocampus.

    PubMed

    Iwano, Tomohiko; Masuda, Aki; Kiyonari, Hiroshi; Enomoto, Hideki; Matsuzaki, Fumio

    2012-08-01

    The brain is composed of diverse types of neurons that fulfill distinct roles in neuronal circuits, as manifested by the hippocampus, where pyramidal neurons and granule cells constitute functionally distinct domains: cornu ammonis (CA) and dentate gyrus (DG), respectively. Little is known about how these two types of neuron differentiate during hippocampal development, although a set of transcription factors that is expressed in progenitor cells is known to be required for the survival of granule cells. Here, we demonstrate in mice that Prox1, a transcription factor constitutively expressed in the granule cell lineage, postmitotically functions to specify DG granule cell identity. Postmitotic elimination of Prox1 caused immature DG neurons to lose the granule cell identity and in turn terminally differentiate into the pyramidal cell type manifesting CA3 neuronal identity. By contrast, Prox1 overexpression caused opposing effects on presumptive hippocampal pyramidal cells. These results indicate that the immature DG cell has the potential to become a granule cell or a pyramidal cell, and Prox1 defines the granule cell identity. This bi-potency is lost in mature DG cells, although Prox1 is still required for correct gene expression in DG granule cells. Thus, our data indicate that Prox1 acts as a postmitotic cell fate determinant for DG granule cells over the CA3 pyramidal cell fate and is crucial for maintenance of the granule cell identity throughout the life.

  6. Hydrogel formulation determines cell fate of fetal and adult neural progenitor cells.

    PubMed

    Aurand, Emily R; Wagner, Jennifer L; Shandas, Robin; Bjugstad, Kimberly B

    2014-01-01

    Hydrogels provide a unique tool for neural tissue engineering. These materials can be customized for certain functions, i.e. to provide cell/drug delivery or act as a physical scaffold. Unfortunately, hydrogel complexities can negatively impact their biocompatibility, resulting in unintended consequences. These adverse effects may be combated with a better understanding of hydrogel chemical, physical, and mechanical properties, and how these properties affect encapsulated neural cells. We defined the polymerization and degradation rates and compressive moduli of 25 hydrogels formulated from different concentrations of hyaluronic acid (HA) and poly(ethylene glycol) (PEG). Changes in compressive modulus were driven primarily by the HA concentration. The in vitro biocompatibility of fetal-derived (fNPC) and adult-derived (aNPC) neural progenitor cells was dependent on hydrogel formulation. Acute survival of fNPC benefited from hydrogel encapsulation. NPC differentiation was divergent: fNPC differentiated into mostly glial cells, compared with neuronal differentiation of aNPC. Differentiation was influenced in part by the hydrogel mechanical properties. This study indicates that there can be a wide range of HA and PEG hydrogels compatible with NPC. Additionally, this is the first study comparing hydrogel encapsulation of NPC derived from different aged sources, with data suggesting that fNPC and aNPC respond dissimilarly within the same hydrogel formulation.

  7. Duration of culture and sonic hedgehog signaling differentially specify PV versus SST cortical interneuron fates from embryonic stem cells.

    PubMed

    Tyson, Jennifer A; Goldberg, Ethan M; Maroof, Asif M; Xu, Qing; Petros, Timothy J; Anderson, Stewart A

    2015-04-01

    Medial ganglionic eminence (MGE)-derived GABAergic cortical interneurons (cINs) consist of multiple subtypes that are involved in many cortical functions. They also have a remarkable capacity to migrate, survive and integrate into cortical circuitry after transplantation into postnatal cortex. These features have engendered considerable interest in generating distinct subgroups of interneurons from pluripotent stem cells (PSCs) for the study of interneuron fate and function, and for the development of cell-based therapies. Although advances have been made, the capacity to generate highly enriched pools of subgroup fate-committed interneuron progenitors from PSCs has remained elusive. Previous studies have suggested that the two main MGE-derived interneuron subgroups--those expressing somatostatin (SST) and those expressing parvalbumin (PV)--are specified in the MGE from Nkx2.1-expressing progenitors at higher or lower levels of sonic hedgehog (Shh) signaling, respectively. To further explore the role of Shh and other factors in cIN fate determination, we generated a reporter line such that Nkx2.1-expressing progenitors express mCherry and postmitotic Lhx6-expressing MGE-derived interneurons express GFP. Manipulations of Shh exposure and time in culture influenced the subgroup fates of ESC-derived interneurons. Exposure to higher Shh levels, and collecting GFP-expressing precursors at 12 days in culture, resulted in the strongest enrichment for SST interneurons over those expressing PV, whereas the strongest enrichment for PV interneurons was produced by lower Shh and by collecting mCherry-expressing cells after 17 days in culture. These findings confirm that fate determination of cIN subgroups is crucially influenced by Shh signaling, and provide a system for the further study of interneuron fate and function. PMID:25804737

  8. Dentin sialophosphoprotein: a regulatory protein for dental pulp stem cell identity and fate.

    PubMed

    Guo, Shiliang; Lim, Dandrich; Dong, Zhihong; Saunders, Thomas L; Ma, Peter X; Marcelo, Cynthia L; Ritchie, Helena H

    2014-12-01

    The dentin sialophosphoprotein (dspp) transcript is expressed during tooth development as a DSPP precursor protein, which then undergoes cleavage to form mature dentin sialoprotein (DSP) and phosphophoryn (PP) proteins. Previous studies using DSPP-knockout (KO) mice have reported that these animals have hypomineralized teeth, thin dentin, and a large dental pulp chamber, similar to those from patients with dentinogenesis imperfecta III. However, there is no information about factors that regulate dental pulp stem cell lineage fate, a critical early event in the odontoblast-dentin mineralization scheme. To reveal the role of DSPP in odontoblast lineage differentiation during tooth development, we systematically examined teeth from wild-type (wt) and DSPP-KO C57BL/6 mice between the ages of postnatal day 1 and 3 months. We found developmental abnormalities not previously reported, such as circular dentin formation within dental pulp cells and altered odontoblast differentiation in DSPP-KO mice, even as early as 1 day after birth. Surprisingly, we also identified chondrocyte-like cells in the dental pulp from KO-mice teeth. Thus, these studies that compare wt and DSPP-KO mice suggest that the expression of DSPP precursor protein is required for normal odontoblast lineage differentiation and that the absence of DSPP allows dental pulp cells to differentiate into chondrocyte-like cells, which could negatively impact pulpal wound healing and tissue regeneration.

  9. The aged brain: genesis and fate of residual progenitor cells in the subventricular zone

    PubMed Central

    Capilla-Gonzalez, Vivian; Herranz-Pérez, Vicente; García-Verdugo, Jose Manuel

    2015-01-01

    Neural stem cells (NSCs) persist in the adult mammalian brain through life. The subventricular zone (SVZ) is the largest source of stem cells in the nervous system, and continuously generates new neuronal and glial cells involved in brain regeneration. During aging, the germinal potential of the SVZ suffers a widespread decline, but the causes of this turn down are not fully understood. This review provides a compilation of the current knowledge about the age-related changes in the NSC population, as well as the fate of the newly generated cells in the aged brain. It is known that the neurogenic capacity is clearly disrupted during aging, while the production of oligodendroglial cells is not compromised. Interestingly, the human brain seems to primarily preserve the ability to produce new oligodendrocytes instead of neurons, which could be related to the development of neurological disorders. Further studies in this matter are required to improve our understanding and the current strategies for fighting neurological diseases associated with senescence. PMID:26441536

  10. Transcriptional and epigenetic control of brown and beige adipose cell fate and function

    PubMed Central

    Inagaki, Takeshi; Sakai, Juro; Kajimura, Shingo

    2016-01-01

    White adipocytes store excess energy in the form of triglycerides, whereas brown and beige adipocytes dissipate energy in the form of heat. This thermogenic function relies on the activation of brown and beige adipocyte-specific gene programmes that are coordinately regulated by adipose-selective chromatin architectures and by a set of unique transcriptional and epigenetic regulators. A number of transcriptional and epigenetic regulators are also required for promoting beige adipocyte biogenesis in response to various environmental stimuli. A better understanding of the molecular mechanisms governing the generation and function of brown and beige adipocytes is necessary to allow us to control adipose cell fate and stimulate thermogenesis. This may provide a therapeutic approach for the treatment of obesity and obesity-associated diseases, such as type 2 diabetes. PMID:27251423

  11. Transcriptional and epigenetic control of brown and beige adipose cell fate and function.

    PubMed

    Inagaki, Takeshi; Sakai, Juro; Kajimura, Shingo

    2016-08-01

    White adipocytes store excess energy in the form of triglycerides, whereas brown and beige adipocytes dissipate energy in the form of heat. This thermogenic function relies on the activation of brown and beige adipocyte-specific gene programmes that are coordinately regulated by adipose-selective chromatin architectures and by a set of unique transcriptional and epigenetic regulators. A number of transcriptional and epigenetic regulators are also required for promoting beige adipocyte biogenesis in response to various environmental stimuli. A better understanding of the molecular mechanisms governing the generation and function of brown and beige adipocytes is necessary to allow us to control adipose cell fate and stimulate thermogenesis. This may provide a therapeutic approach for the treatment of obesity and obesity-associated diseases, such as type 2 diabetes.

  12. Competing to coordinate cell fate decisions: the MST2-Raf-1 signaling device

    PubMed Central

    Nguyen, Lan K; Matallanas, David G; Romano, David; Kholodenko, Boris N; Kolch, Walter

    2015-01-01

    How do biochemical signaling pathways generate biological specificity? This question is fundamental to modern biology, and its enigma has been accentuated by the discovery that most proteins in signaling networks serve multifunctional roles. An answer to this question may lie in analyzing network properties rather than individual traits of proteins in order to elucidate design principles of biochemical networks that enable biological decision-making. We discuss how this is achieved in the MST2/Hippo-Raf-1 signaling network with the help of mathematical modeling and model-based analysis, which showed that competing protein interactions with affinities controlled by dynamic protein modifications can function as Boolean computing devices that determine cell fate decisions. In addition, we discuss areas of interest for future research and highlight how systems approaches would be of benefit. PMID:25607644

  13. Detection and fate of Bacillus anthracis (Sterne) vegetative cells and spores added to bulk tank milk.

    PubMed

    Perdue, Michael L; Karns, Jeff; Higgins, Jim; Van Kessel, Jo Ann

    2003-12-01

    A preparation of Bacillus anthracis (Sterne strain) spores was used to evaluate commercially available reagents and portable equipment for detecting anthrax contamination by using real-time PCR and was used to assess the fate of spores added directly to bulk tank milk. The Ruggedized Advanced Pathogen Identification Device (RAPID) was employed to detect spores in raw milk down to a concentration of 2,500 spores per ml. Commercially available primers and probes developed to detect either the protective antigen gene or the lethal factor gene both provided easily read positive signals with the RAPID following extraction from milk with a commercially available DNA extraction kit. Nucleotide sequence analysis of the vrrA gene with the use of DNA extracted from spiked milk provided molecular data that readily identified the spores as B. anthracis with a 100% BLAST match to the Sterne and Ames strains and easily distinguished them from B. cereus. Physical-fate and thermal-stability studies demonstrated that spores and vegetative cells have a strong affinity for the cream fraction of whole milk. A single treatment at standard pasteurization temperatures, while 100% lethal to vegetative cells, had no effect on spore viability even 14 days after the treatment. Twenty-four hours after the first treatment, a second treatment at 72 degrees C for 15 s reduced the viability of the population by ca. 99% but still did not kill all of the spores. From these studies, we conclude that standard pasteurization techniques for milk would have little effect on the viability of B. anthracis spores and that raw or pasteurized milk poses no obstacles to the rapid detection of the spores by molecular techniques.

  14. Asymmetric cell division in the Drosophila bristle lineage: from the polarization of sensory organ precursor cells to Notch-mediated binary fate decision

    PubMed Central

    Schweisguth, François

    2015-01-01

    Asymmetric cell division (ACD) is a simple and evolutionary conserved process whereby a mother divides to generate two daughter cells with distinct developmental potentials. This process can generate cell fate diversity during development. Fate asymmetry may result from the unequal segregation of molecules and/or organelles between the two daughter cells. Here, I will review how fate asymmetry is regulated in the sensory bristle lineage in Drosophila and focus on the molecular mechanisms underlying ACD of the sensory organ precursor cells (SOPs). WIREs Dev Biol 2015, 4:299–309. doi: 10.1002/wdev.175 For further resources related to this article, please visit theWIREs website. Conflict of interest: The author has declared no conflicts of interest for this article. PMID:25619594

  15. CAM and cell fate targeting: molecular and energetic insights into cell growth and differentiation.

    PubMed

    Ventura, Carlo

    2005-09-01

    Evidence-based medicine is switching from the analysis of single diseases at a time toward an integrated assessment of a diseased person. Complementary and alternative medicine (CAM) offers multiple holistic approaches, including osteopathy, homeopathy, chiropractic, acupuncture, herbal and energy medicine and meditation, all potentially impacting on major human diseases. It is now becoming evident that acupuncture can modify the expression of different endorphin genes and the expression of genes encoding for crucial transcription factors in cellular homeostasis. Extremely low frequency magnetic fields have been found to prime the commitment to a myocardial lineage in mouse embryonic stem cells, suggesting that magnetic energy may direct stem cell differentiation into specific cellular phenotypes without the aid of gene transfer technologies. This finding may pave the way to novel approaches in tissue engineering and regeneration. Different ginseng extracts have been shown to modulate growth and differentiation in pluripotent cells and to exert wound-healing and antitumor effects through opposing activities on the vascular system, prompting the hypothesis that ancient compounds may be the target for new logics in cell therapy. These observations and the subtle entanglement among different CAM systems suggest that CAM modalities may deeply affect both the signaling and transcriptional level of cellular homeostasis. Such a perception holds promises for a new era in CAM, prompting reproducible documentation of biological responses to CAM-related strategies and compounds. To this end, functional genomics and proteomics and the comprehension of the cell signaling networks may substantially contribute to the development of a molecular evidence-based CAM.

  16. Asymmetric division of contractile domains couples cell positioning and fate specification.

    PubMed

    Maître, Jean-Léon; Turlier, Hervé; Illukkumbura, Rukshala; Eismann, Björn; Niwayama, Ritsuya; Nédélec, François; Hiiragi, Takashi

    2016-08-18

    During pre-implantation development, the mammalian embryo self-organizes into the blastocyst, which consists of an epithelial layer encapsulating the inner-cell mass (ICM) giving rise to all embryonic tissues. In mice, oriented cell division, apicobasal polarity and actomyosin contractility are thought to contribute to the formation of the ICM. However, how these processes work together remains unclear. Here we show that asymmetric segregation of the apical domain generates blastomeres with different contractilities, which triggers their sorting into inner and outer positions. Three-dimensional physical modelling of embryo morphogenesis reveals that cells internalize only when differences in surface contractility exceed a predictable threshold. We validate this prediction using biophysical measurements, and successfully redirect cell sorting within the developing blastocyst using maternal myosin (Myh9)-knockout chimaeric embryos. Finally, we find that loss of contractility causes blastomeres to show ICM-like markers, regardless of their position. In particular, contractility controls Yap subcellular localization, raising the possibility that mechanosensing occurs during blastocyst lineage specification. We conclude that contractility couples the positioning and fate specification of blastomeres. We propose that this ensures the robust self-organization of blastomeres into the blastocyst, which confers remarkable regulative capacities to mammalian embryos. PMID:27487217

  17. Nanotopography drives stem cell fate toward osteoblast differentiation through α1β1 integrin signaling pathway.

    PubMed

    Rosa, A L; Kato, R B; Castro Raucci, L M S; Teixeira, L N; de Oliveira, F S; Bellesini, L S; de Oliveira, P T; Hassan, M Q; Beloti, M M

    2014-03-01

    The aim of our study was to investigate the osteoinductive potential of a titanium (Ti) surface with nanotopography, using mesenchymal stem cells (MSCs) and the mechanism involved in this phenomenon. Polished Ti discs were chemically treated with H2 SO4 /H2 O2 to yield nanotopography and rat MSCs were cultured under osteogenic and non-osteogenic conditions on both nanotopography and untreated polished (control) Ti surfaces. The nanotopography increased cell proliferation and alkaline phosphatase (Alp) activity and upregulated the gene expression of key bone markers of cells grown under both osteogenic and non-osteogenic conditions. Additionally, the gene expression of α1 and β1 integrins was higher in cells grown on Ti with nanotopography under non-osteogeneic condition compared with control Ti surface. The higher gene expression of bone markers and Alp activity induced by Ti with nanotopography was reduced by obtustatin, an α1β1 integrin inhibitor. These results indicate that α1β1 integrin signaling pathway determines the osteoinductive effect of nanotopography on MSCs. This finding highlights a novel mechanism involved in nanosurface-mediated MSCs fate and may contribute to the development of new surface modifications aiming to accelerate and/or enhance the process of osseointegration.

  18. Unique pharmacological actions of atypical neuroleptic quetiapine: possible role in cell cycle/fate control

    PubMed Central

    Kondo, M A; Tajinda, K; Colantuoni, C; Hiyama, H; Seshadri, S; Huang, B; Pou, S; Furukori, K; Hookway, C; Jaaro-Peled, H; Kano, S-i; Matsuoka, N; Harada, K; Ni, K; Pevsner, J; Sawa, A

    2013-01-01

    Quetiapine is an atypical neuroleptic with a pharmacological profile distinct from classic neuroleptics that function primarily via blockade of dopamine D2 receptors. In the United States, quetiapine is currently approved for treating patients with schizophrenia, major depression and bipolar I disorder. Despite its widespread use, its cellular effects remain elusive. To address possible mechanisms, we chronically treated mice with quetiapine, haloperidol or vehicle and examined quetiapine-specific gene expression change in the frontal cortex. Through microarray analysis, we observed that several groups of genes were differentially expressed upon exposure to quetiapine compared with haloperidol or vehicle; among them, Cdkn1a, the gene encoding p21, exhibited the greatest fold change relative to haloperidol. The quetiapine-induced downregulation of p21/Cdkn1a was confirmed by real-time polymerase chain reaction and in situ hybridization. Consistent with single gene-level analyses, functional group analyses also indicated that gene sets associated with cell cycle/fate were differentially regulated in the quetiapine-treated group. In cortical cell cultures treated with quetiapine, p21/Cdkn1a was significantly downregulated in oligodendrocyte precursor cells and neurons, but not in astrocytes. We propose that cell cycle-associated intervention by quetiapine in the frontal cortex may underlie a unique efficacy of quetiapine compared with typical neuroleptics. PMID:23549417

  19. Phosphatidylcholine biosynthesis during neuronal differentiation and its role in cell fate determination.

    PubMed

    Marcucci, Hebe; Paoletti, Luciana; Jackowski, Suzanne; Banchio, Claudia

    2010-08-13

    Neuronal differentiation is characterized by neuritogenesis and neurite outgrowth, processes that are dependent on membrane biosynthesis. Thus, the production of phosphatidylcholine (PtdCho), the major membrane phospholipid, should be stimulated during neuronal differentiation. We demonstrate that during retinoic acid (RA)-induced differentiation of Neuro-2a cells, PtdCho synthesis was promoted by an ordered and sequential activation of choline kinase alpha (CK(alpha)) and choline cytidylyltransferase alpha (CCT(alpha)). Early after RA stimulation, the increase in PtdCho synthesis is mainly governed by the biochemical activation of CCT(alpha). Later, the transcription of CK(alpha)- and CCT(alpha)-encoding genes was induced. Both PtdCho biosynthesis and neuronal differentiation are dependent on ERK activation. A novel mechanism is proposed by which PtdCho biosynthesis is coordinated during neuronal differentiation. Enforced expression of either CK(alpha) or CCTalpha increased the rate of synthesis and the amount of PtdCho, and these cells initiated differentiation without RA stimulation, as evidenced by cell morphology and the expression of genes associated with neuritogenesis. The differentiation resulting from enforced expression of CCT(alpha) or CK(alpha) was dependent on persistent ERK activation. These results indicate that elevated PtdCho synthesis could mimic the RA signals and thus determine neuronal cell fate. Moreover, they could explain the key role that PtdCho plays during neuronal regeneration. PMID:20525991

  20. Antigen availability determines CD8⁺ T cell-dendritic cell interaction kinetics and memory fate decisions.

    PubMed

    Henrickson, Sarah E; Perro, Mario; Loughhead, Scott M; Senman, Balimkiz; Stutte, Susanne; Quigley, Michael; Alexe, Gabriela; Iannacone, Matteo; Flynn, Michael P; Omid, Shaida; Jesneck, Jonathan L; Imam, Sabrina; Mempel, Thorsten R; Mazo, Irina B; Haining, W Nicholas; von Andrian, Ulrich H

    2013-09-19

    T cells are activated by antigen (Ag)-bearing dendritic cells (DCs) in lymph nodes in three phases. The duration of the initial phase of transient, serial DC-T cell interactions is inversely correlated with Ag dose. The second phase, characterized by stable DC-T cell contacts, is believed to be necessary for full-fledged T cell activation. Here we have shown that this is not the case. CD8⁺ T cells interacting with DCs presenting low-dose, short-lived Ag did not transition to phase 2, whereas higher Ag dose yielded phase 2 transition. Both antigenic constellations promoted T cell proliferation and effector differentiation but yielded different transcriptome signatures at 12 hr and 24 hr. T cells that experienced phase 2 developed long-lived memory, whereas conditions without stable contacts yielded immunological amnesia. Thus, T cells make fate decisions within hours after Ag exposure, resulting in long-term memory or abortive effector responses, correlating with T cell-DCs interaction kinetics.

  1. Antigen availability determines CD8⁺ T cell-dendritic cell interaction kinetics and memory fate decisions.

    PubMed

    Henrickson, Sarah E; Perro, Mario; Loughhead, Scott M; Senman, Balimkiz; Stutte, Susanne; Quigley, Michael; Alexe, Gabriela; Iannacone, Matteo; Flynn, Michael P; Omid, Shaida; Jesneck, Jonathan L; Imam, Sabrina; Mempel, Thorsten R; Mazo, Irina B; Haining, W Nicholas; von Andrian, Ulrich H

    2013-09-19

    T cells are activated by antigen (Ag)-bearing dendritic cells (DCs) in lymph nodes in three phases. The duration of the initial phase of transient, serial DC-T cell interactions is inversely correlated with Ag dose. The second phase, characterized by stable DC-T cell contacts, is believed to be necessary for full-fledged T cell activation. Here we have shown that this is not the case. CD8⁺ T cells interacting with DCs presenting low-dose, short-lived Ag did not transition to phase 2, whereas higher Ag dose yielded phase 2 transition. Both antigenic constellations promoted T cell proliferation and effector differentiation but yielded different transcriptome signatures at 12 hr and 24 hr. T cells that experienced phase 2 developed long-lived memory, whereas conditions without stable contacts yielded immunological amnesia. Thus, T cells make fate decisions within hours after Ag exposure, resulting in long-term memory or abortive effector responses, correlating with T cell-DCs interaction kinetics. PMID:24054328

  2. FGFR2IIIb-MAPK Activity Is Required for Epithelial Cell Fate Decision in the Lower Müllerian Duct.

    PubMed

    Terakawa, Jumpei; Rocchi, Altea; Serna, Vanida A; Bottinger, Erwin P; Graff, Jonathan M; Kurita, Takeshi

    2016-07-01

    Cell fate of lower Müllerian duct epithelium (MDE), to become uterine or vaginal epithelium, is determined by the absence or presence of ΔNp63 expression, respectively. Previously, we showed that SMAD4 and runt-related transcription factor 1 (RUNX1) were independently required for MDE to express ΔNp63. Here, we report that vaginal mesenchyme directs vaginal epithelial cell fate in MDE through paracrine activation of fibroblast growth factor (FGF) receptor-MAPK pathway. In the developing reproductive tract, FGF7 and FGF10 were enriched in vaginal mesenchyme, whereas FGF receptor 2IIIb was expressed in epithelia of both the uterus and vagina. When Fgfr2 was inactivated, vaginal MDE underwent uterine cell fate, and this differentiation defect was corrected by activation of MEK-ERK pathway. In vitro, FGF10 in combination with bone morphogenetic protein 4 and activin A (ActA) was sufficient to induce ΔNp63 in MDE, and ActA was essential for induction of RUNX1 through SMAD-independent pathways. Accordingly, inhibition of type 1 receptors for activin in neonatal mice induced uterine differentiation in vaginal epithelium by down-regulating RUNX1, whereas conditional deletion of Smad2 and Smad3 had no effect on vaginal epithelial differentiation. In conclusion, vaginal epithelial cell fate in MDE is induced by FGF7/10-MAPK, bone morphogenetic protein 4-SMAD, and ActA-RUNX1 pathway activities, and the disruption in any one of these pathways results in conversion from vaginal to uterine epithelial cell fate. PMID:27164167

  3. The MYB23 gene provides a positive feedback loop for cell fate specification in the Arabidopsis root epidermis.

    PubMed

    Kang, Yeon Hee; Kirik, Victor; Hulskamp, Martin; Nam, Kyoung Hee; Hagely, Katherine; Lee, Myeong Min; Schiefelbein, John

    2009-04-01

    The specification of cell fates during development requires precise regulatory mechanisms to ensure robust cell type patterns. Theoretical models of pattern formation suggest that a combination of negative and positive feedback mechanisms are necessary for efficient specification of distinct fates in a field of differentiating cells. Here, we examine the role of the R2R3-MYB transcription factor gene, AtMYB23 (MYB23), in the establishment of the root epidermal cell type pattern in Arabidopsis thaliana. MYB23 is closely related to, and is positively regulated by, the WEREWOLF (WER) MYB gene during root epidermis development. Furthermore, MYB23 is able to substitute for the function of WER and to induce its own expression when controlled by WER regulatory sequences. We also show that the MYB23 protein binds to its own promoter, suggesting a MYB23 positive feedback loop. The localization of MYB23 transcripts and MYB23-green fluorescent protein (GFP) fusion protein, as well as the effect of a chimeric MYB23-SRDX repressor construct, links MYB23 function to the developing non-hair cell type. Using mutational analyses, we find that MYB23 is necessary for precise establishment of the root epidermal pattern, particularly under conditions that compromise the cell specification process. These results suggest that MYB23 participates in a positive feedback loop to reinforce cell fate decisions and ensure robust establishment of the cell type pattern in the Arabidopsis root epidermis.

  4. Fate of graft cells: what should be clarified for development of mesenchymal stem cell therapy for ischemic stroke?

    PubMed Central

    Ikegame, Yuka; Yamashita, Kentaro; Nakashima, Shigeru; Nomura, Yuichi; Yonezawa, Shingo; Asano, Yoshitaka; Shinoda, Jun; Hara, Hideaki; Iwama, Toru

    2014-01-01

    Mesenchymal stem cells (MSCs) are believed to be promising for cell administration therapy after ischemic stroke. Because of their advantageous characteristics, such as ability of differentiation into neurovascular lineages, avoidance of immunological problems, and abundance of graft cells in mesodermal tissues, studies regarding MSC therapy have increased recently. However, several controversies are yet to be resolved before a worldwide consensus regarding a standard protocol is obtained. In particular, the neuroprotective effects, the rate of cell migration to the lesion, and differentiation direction differ depending on preclinical observations. Analyses of these differences and application of recent developments in stem cell biology or engineering in imaging modality may contribute to identification of criteria for optimal stem cell therapy in which reliable protocols, which control cell quality and include safe administration procedures, are defined for each recovery phase after cerebral ischemia. In this mini review, we examine controversies regarding the fate of grafts and the prospects for advanced therapy that could be obtained through recent developments in stem cell research as direct conversion to neural cells. PMID:25374506

  5. Data integration for identification of important transcription factors of STAT6-mediated cell fate decisions.

    PubMed

    Jargosch, M; Kröger, S; Gralinska, E; Klotz, U; Fang, Z; Chen, W; Leser, U; Selbig, J; Groth, D; Baumgrass, R

    2016-06-24

    Data integration has become a useful strategy for uncovering new insights into complex biological networks. We studied whether this approach can help to delineate the signal transducer and activator of transcription 6 (STAT6)-mediated transcriptional network driving T helper (Th) 2 cell fate decisions. To this end, we performed an integrative analysis of publicly available RNA-seq data of Stat6-knockout mouse studies together with STAT6 ChIP-seq data and our own gene expression time series data during Th2 cell differentiation. We focused on transcription factors (TFs), cytokines, and cytokine receptors and delineated 59 positively and 41 negatively STAT6-regulated genes, which were used to construct a transcriptional network around STAT6. The network illustrates that important and well-known TFs for Th2 cell differentiation are positively regulated by STAT6 and act either as activators for Th2 cells (e.g., Gata3, Atf3, Satb1, Nfil3, Maf, and Pparg) or as suppressors for other Th cell subpopulations such as Th1 (e.g., Ar), Th17 (e.g., Etv6), or iTreg (e.g., Stat3 and Hif1a) cells. Moreover, our approach reveals 11 TFs (e.g., Atf5, Creb3l2, and Asb2) with unknown functions in Th cell differentiation. This fact together with the observed enrichment of asthma risk genes among those regulated by STAT6 underlines the potential value of the data integration strategy used here. Thus, our results clearly support the opinion that data integration is a useful tool to delineate complex physiological processes.

  6. Data integration for identification of important transcription factors of STAT6-mediated cell fate decisions.

    PubMed

    Jargosch, M; Kröger, S; Gralinska, E; Klotz, U; Fang, Z; Chen, W; Leser, U; Selbig, J; Groth, D; Baumgrass, R

    2016-01-01

    Data integration has become a useful strategy for uncovering new insights into complex biological networks. We studied whether this approach can help to delineate the signal transducer and activator of transcription 6 (STAT6)-mediated transcriptional network driving T helper (Th) 2 cell fate decisions. To this end, we performed an integrative analysis of publicly available RNA-seq data of Stat6-knockout mouse studies together with STAT6 ChIP-seq data and our own gene expression time series data during Th2 cell differentiation. We focused on transcription factors (TFs), cytokines, and cytokine receptors and delineated 59 positively and 41 negatively STAT6-regulated genes, which were used to construct a transcriptional network around STAT6. The network illustrates that important and well-known TFs for Th2 cell differentiation are positively regulated by STAT6 and act either as activators for Th2 cells (e.g., Gata3, Atf3, Satb1, Nfil3, Maf, and Pparg) or as suppressors for other Th cell subpopulations such as Th1 (e.g., Ar), Th17 (e.g., Etv6), or iTreg (e.g., Stat3 and Hif1a) cells. Moreover, our approach reveals 11 TFs (e.g., Atf5, Creb3l2, and Asb2) with unknown functions in Th cell differentiation. This fact together with the observed enrichment of asthma risk genes among those regulated by STAT6 underlines the potential value of the data integration strategy used here. Thus, our results clearly support the opinion that data integration is a useful tool to delineate complex physiological processes. PMID:27420972

  7. Feedbacks, Bifurcations, and Cell Fate Decision-Making in the p53 System

    PubMed Central

    Bogdał, Marta N.; Lipniacki, Tomasz

    2016-01-01

    The p53 transcription factor is a regulator of key cellular processes including DNA repair, cell cycle arrest, and apoptosis. In this theoretical study, we investigate how the complex circuitry of the p53 network allows for stochastic yet unambiguous cell fate decision-making. The proposed Markov chain model consists of the regulatory core and two subordinated bistable modules responsible for cell cycle arrest and apoptosis. The regulatory core is controlled by two negative feedback loops (regulated by Mdm2 and Wip1) responsible for oscillations, and two antagonistic positive feedback loops (regulated by phosphatases Wip1 and PTEN) responsible for bistability. By means of bifurcation analysis of the deterministic approximation we capture the recurrent solutions (i.e., steady states and limit cycles) that delineate temporal responses of the stochastic system. Direct switching from the limit-cycle oscillations to the “apoptotic” steady state is enabled by the existence of a subcritical Neimark—Sacker bifurcation in which the limit cycle loses its stability by merging with an unstable invariant torus. Our analysis provides an explanation why cancer cell lines known to have vastly diverse expression levels of Wip1 and PTEN exhibit a broad spectrum of responses to DNA damage: from a fast transition to a high level of p53 killer (a p53 phosphoform which promotes commitment to apoptosis) in cells characterized by high PTEN and low Wip1 levels to long-lasting p53 level oscillations in cells having PTEN promoter methylated (as in, e.g., MCF-7 cell line). PMID:26928575

  8. Quantifying Waddington landscapes and paths of non-adiabatic cell fate decisions for differentiation, reprogramming and transdifferentiation

    PubMed Central

    Li, Chunhe; Wang, Jin

    2013-01-01

    Cellular differentiation, reprogramming and transdifferentiation are determined by underlying gene regulatory networks. Non-adiabatic regulation via slow binding/unbinding to the gene can be important in these cell fate decision-making processes. Based on a stem cell core gene network, we uncovered the stem cell developmental landscape. As the binding/unbinding speed decreases, the landscape topography changes from bistable attractors of stem and differentiated states to more attractors of stem and other different cell states as well as substates. Non-adiabaticity leads to more differentiated cell types and provides a natural explanation for the heterogeneity observed in the experiments. We quantified Waddington landscapes with two possible cell fate decision mechanisms by changing the regulation strength or regulation timescale (non-adiabaticity). Transition rates correlate with landscape topography through barrier heights between different states and quantitatively determine global stability. We found the optimal speeds of these cell fate decision-making processes. We quantified biological paths and predict that differentiation and reprogramming go through an intermediate state (IM1), whereas transdifferentiation goes through another intermediate state (IM2). Some predictions are confirmed by recent experimental studies. PMID:24132204

  9. TGFβ signaling regulates the choice between pluripotent and neural fates during reprogramming of human urine derived cells

    PubMed Central

    Wang, Lihui; Li, Xirui; Huang, Wenhao; Zhou, Tiancheng; Wang, Haitao; Lin, Aiping; Hutchins, Andrew Paul; Su, Zhenghui; Chen, Qianyu; Pei, Duanqing; Pan, Guangjin

    2016-01-01

    Human urine cells (HUCs) can be reprogrammed into neural progenitor cells (NPCs) or induced pluripotent stem cells (iPSCs) with defined factors and a small molecule cocktail, but the underlying fate choice remains unresolved. Here, through sequential removal of individual compound from small molecule cocktail, we showed that A8301, a TGFβ signaling inhibitor, is sufficient to switch the cell fate from iPSCs into NPCs in OSKM-mediated HUCs reprogramming. However, TGFβ exposure at early stage inhibits HUCs reprogramming by promoting EMT. Base on these data, we developed an optimized approach for generation of NPCs or iPSCs from HUCs with significantly improved efficiency by regulating TGFβ activity at different reprogramming stages. This approach provides a simplified and improved way for HUCs reprogramming, thus would be valuable for banking human iPSCs or NPCs from people with different genetic background. PMID:26935433

  10. Three-dimensional nano-biointerface as a new platform for guiding cell fate.

    PubMed

    Liu, Xueli; Wang, Shutao

    2014-04-21

    Three-dimensional nano-biointerface has been emerging as an important topic for chemistry, nanotechnology, and life sciences in recent years. Understanding the exchanges of materials, signals, and energy at biological interfaces has inspired and helped the serial design of three-dimensional nano-biointerfaces. The intimate interactions between cells and nanostructures bring many novel properties, making three-dimensional nano-biointerfaces a powerful platform to guide cell fate in a controllable and accurate way. These advantages and capabilities endow three-dimensional nano-biointerfaces with an indispensable role in developing advanced biological science and technology. This tutorial review is mainly focused on the recent progress of three-dimensional nano-biointerfaces and highlights the new explorations and unique phenomena of three-dimensional nano-biointerfaces for cell-related fundamental studies and biomedical applications. Some basic bio-inspired principles for the design and creation of three-dimensional nano-biointerfaces are also delivered in this review. Current and further challenges of three-dimensional nano-biointerfaces are finally addressed and proposed.

  11. Quantifying Cell Fate Decisions for Differentiation and Reprogramming of a Human Stem Cell Network: Landscape and Biological Paths

    PubMed Central

    Li, Chunhe; Wang, Jin

    2013-01-01

    Cellular reprogramming has been recently intensively studied experimentally. We developed a global potential landscape and kinetic path framework to explore a human stem cell developmental network composed of 52 genes. We uncovered the underlying landscape for the stem cell network with two basins of attractions representing stem and differentiated cell states, quantified and exhibited the high dimensional biological paths for the differentiation and reprogramming process, connecting the stem cell state and differentiated cell state. Both the landscape and non-equilibrium curl flux determine the dynamics of cell differentiation jointly. Flux leads the kinetic paths to be deviated from the steepest descent gradient path, and the corresponding differentiation and reprogramming paths are irreversible. Quantification of paths allows us to find out how the differentiation and reprogramming occur and which important states they go through. We show the developmental process proceeds as moving from the stem cell basin of attraction to the differentiation basin of attraction. The landscape topography characterized by the barrier heights and transition rates quantitatively determine the global stability and kinetic speed of cell fate decision process for development. Through the global sensitivity analysis, we provided some specific predictions for the effects of key genes and regulation connections on the cellular differentiation or reprogramming process. Key links from sensitivity analysis and biological paths can be used to guide the differentiation designs or reprogramming tactics. PMID:23935477

  12. Protein dependent fate of hepatic cells under nicotine induced stress and curcumin ameliorated condition.

    PubMed

    Banerjee, Satyam; Chattopadhyay, Krishna; Chhabra, Jasmeet Kaur; Chattopadhyay, Brajadulal

    2012-06-01

    Nicotine is mainly metabolized in liver. Its abuse elicits acute phase response by activating macrophages to produce pro-inflammatory cytokines, which play critical role in apoptosis or cell proliferation. The protective pharmacological mechanism of curcumin against nicotine-induced toxicity on protein malnourished liver is still remaining unclear. This study investigated the ameliorative mechanism of curcumin against nicotine-induced toxicity and also fate of liver particularly under protein restricted condition. Female Albino-rats maintained under normal/protein-restricted diets, were subcutaneously injected with nicotine tartrate (2.5 mg/kg body weight/day) and orally supplemented with curcumin (80 mg/kg body weight/day) for 21 days. The animals were then sacrificed to dissect out liver and proceed with further experiments. Interactions of nicotine with DNA both in vivo and in vitro were observed by thermal denaturation and DNA laddering assays. Effects of nicotine on hepatic cells were monitored by differential staining, comet assay, cytokine profiling, mRNA and protein expression. Nicotine caused more intense DNA damage, promoted hepatic cell death through up-regulating pro-apoptotic proteins and signaling molecules in protein malnourished individuals. Through up-regulation of anti-apoptotic proteins and proliferation promoting molecules, nicotine dysregulated homeostasis in normal protein condition. Curcumin significantly ameliorated the nicotine-induced toxicity in both conditions and regulated the imbalance between cell survival and death induced by nicotine. The protein content present in the nicotine induced hepatic cell decides either cell-survival pathway or cytotoxic pathway. PMID:22381069

  13. Differential seed handling by two African primates affects seed fate and establishment of large-seeded trees

    NASA Astrophysics Data System (ADS)

    Gross-Camp, Nicole D.; Kaplin, Beth A.

    2011-11-01

    We examined the influence of seed handling by two semi-terrestrial African forest primates, chimpanzees ( Pan troglodytes) and l'Hoest's monkeys ( Cercopithecus lhoesti), on the fate of large-seeded tree species in an afromontane forest. Chimpanzees and l'Hoest's monkeys dispersed eleven seed species over one year, with quantity and quality of dispersal varying through time. Primates differed in their seed handling behaviors with chimpanzees defecating large seeds (>0.5 cm) significantly more than l'Hoest's. Furthermore, they exhibited different oral-processing techniques with chimpanzees discarding wadges containing many seeds and l'Hoest's monkeys spitting single seeds. A PCA examined the relationship between microhabitat characteristics and the site where primates deposited seeds. The first two components explained almost half of the observed variation. Microhabitat characteristics associated with sites where seeds were defecated had little overlap with those characteristics describing where spit seeds arrived, suggesting that seed handling in part determines the location where seeds are deposited. We monitored a total of 552 seed depositions through time, recording seed persistence, germination, and establishment. Defecations were deposited significantly farther from an adult conspecific than orally-discarded seeds where they experienced the greatest persistence but poorest establishment. In contrast, spit seeds were deposited closest to an adult conspecific but experienced the highest seed establishment rates. We used experimental plots to examine the relationship between seed handling, deposition site, and seed fate. We found a significant difference in seed handling and fate, with undispersed seeds in whole fruits experiencing the lowest establishment rates. Seed germination differed by habitat type with open forest experiencing the highest rates of germination. Our results highlight the relationship between primate seed handling and deposition site and seed

  14. Repression of Hedgehog signalling is required for the acquisition of dorsolateral cell fates in the zebrafish otic vesicle

    PubMed Central

    Hammond, Katherine L.; van Eeden, Fredericus J. M.; Whitfield, Tanya T.

    2010-01-01

    In zebrafish, Hedgehog (Hh) signalling from ventral midline structures is necessary and sufficient to specify posterior otic identity. Loss of Hh signalling gives rise to mirror symmetric ears with double anterior character, whereas severe upregulation of Hh signalling leads to double posterior ears. By contrast, in mouse and chick, Hh is predominantly required for dorsoventral otic patterning. Whereas a loss of Hh function in zebrafish does not affect dorsoventral and mediolateral otic patterning, we now show that a gain of Hh signalling activity causes ventromedial otic territories to expand at the expense of dorsolateral domains. In a panel of lines carrying mutations in Hh inhibitor genes, Hh pathway activity is increased throughout the embryo, and dorsolateral otic structures are lost or reduced. Even a modest increase in Hh signalling has consequences for patterning the ear. In ptc1–/– and ptc2–/– mutant embryos, in which Hh signalling is maximal throughout the embryo, the inner ear is severely ventralised and medialised, in addition to displaying the previously reported double posterior character. Transplantation experiments suggest that the effects of the loss of Hh pathway inhibition on the ear are mediated directly. These new data suggest that Hh signalling must be kept tightly repressed for the correct acquisition of dorsolateral cell fates in the zebrafish otic vesicle, revealing distinct similarities between the roles of Hh signalling in zebrafish and amniote inner ear patterning. PMID:20223756

  15. Yes-associated protein in the liver: Regulation of hepatic development, repair, cell fate determination and tumorigenesis.

    PubMed

    Nguyen, Quy; Anders, Robert A; Alpini, Gianfranco; Bai, Haibo

    2015-10-01

    The liver is a vital organ that plays a major role in many bodily functions from protein production and blood clotting to cholesterol, glucose and iron metabolism and nutrition storage. Maintenance of liver homeostasis is critical for these essential bodily functions and disruption of liver homeostasis causes various kinds of liver diseases, some of which have high mortality rate. Recent research advances of the Hippo signalling pathway have revealed its nuclear effector, Yes-associated protein, as an important regulator of liver development, repair, cell fate determination and tumorigenesis. Therefore, a precise control of Yes-associated protein activity is critical for the maintenance of liver homeostasis. This review is going to summarize the discoveries on how the manipulation of Yes-associated protein activity affects liver homeostasis and induces liver diseases and the regulatory mechanisms that determine the Yes-associated protein activity in the liver. Finally, we will discuss the potential of targeting Yes-associated protein as therapeutic strategies in liver diseases.

  16. Leptin changes differentiation fate and induces senescence in chondrogenic progenitor cells

    PubMed Central

    Zhao, X; Dong, Y; Zhang, J; Li, D; Hu, G; Yao, J; Li, Y; Huang, P; Zhang, M; Zhang, J; Huang, Z; Zhang, Y; Miao, Y; Xu, Q; Li, H

    2016-01-01

    Body weight is a component of the mechanical theory of OA (osteoarthritis) pathogenesis. Obesity was also found to be a risk factor for digital OA involving non-weight-bearing joints, which suggested that metabolism influences the occurrence and progression of OA. The metabolic origin of OA has been partially attributed to the involvement of adipokines, such as leptin, the levels of which are significantly and positively correlated with cartilage degeneration in OA patients. However, the mechanisms by which leptin-induced cartilage degeneration occurs are poorly understood. The discovery of chondrogenic progenitor cells (CPCs) opened up new opportunities for investigation. Investigating the effects of leptin on differentiation and proliferation in CPCs would increase our understanding of the roles played by leptin in the aetiology and development of OA. Here, CPCs were harvested using single-cell sorting from rat cartilage tissues to obtain mesenchymal stem-like cells, which possess clonogenicity, proliferation and stemness. High doses of leptin decreased the ability of the CPCs to migrate, inhibited their chondrogenic potential and increased their osteogenic potential, suggesting that leptin changes differentiation fates in CPCs. High doses of leptin induced cell cycle arrest and senescence in CPCs by activating the p53/p21 pathway and inhibiting the Sirt1 pathway. Inhibiting the Sirt1 pathway accelerated cartilage senescence in knockout (KO) mice. Activating the leptin pathway induced higher Ob-Rb expression and was significantly correlated with cartilage degeneration (lower levels of Coll-2) and tissue senescence (higher levels of p53/p21 and lower levels of Sirt1) in OA patients, suggesting that leptin-induced CPCs senescence contributes to the development of OA. Taken together, our results reveal new links between obesity and cartilage damage that are induced by leptin-mediated effects on cell behaviour and senescence. PMID:27077804

  17. Effects of magnesium degradation products on mesenchymal stem cell fate and osteoblastogenesis.

    PubMed

    Luthringer, Bérengère J C; Willumeit-Römer, Regine

    2016-01-01

    The unique properties of magnesium (Mg) and its alloys that combine favourable mechanical properties, biocompatibility, and biodegradability, which until now have been restricted primarily to polymers, justify its study in the field of implantology. Previous in vivo studies have underlined the possible osteoconductive effects of Mg-based metals, and several in vitro studies have highlighted positive effects of Mg-enriched biomaterials. However, although the observed biological activity of magnesium is intriguing, it remains largely unexplored. Furthermore, due to increased regulations, the introduction of new implants on the market must be accompanied by thorough mechanistic understanding. Therefore, to mimic the in vivo effects of the degradation of Mg-based implants on mesenchymal stem cell differentiation during bone remodelling, non-haematopoietic multipotent foetal progenitor cells, i.e., human umbilical cord perivascular cells (HUCPV), were cultured for up to three weeks with or without osteoblastic differentiating media and with or without magnesium extract (approximately 5mM). To partially unveil the mechanism or to select paths for further investigation, a very broad selection of genes was chosen (e.g., those involved in osmolality sensing). Several classical bone markers were also studied at the gene and protein levels. The data suggest that Mg extract alone potentiates cell proliferation or delays the natural fate of maturation/differentiation. However, when the cells are driven toward osteoblastic differentiation, the effect of the Mg extract becomes much more complex, positively or negatively influencing differentiation via various pathways. These preliminary results confirm the choice of the various parameters utilised here and highzlight the importance of further studies.

  18. Surface Chemistry of Nanoscale Mineralized Collagen Regulates Periodontal Ligament Stem Cell Fate.

    PubMed

    Fu, Yu; Liu, Shuai; Cui, Sheng-Jie; Kou, Xiao-Xing; Wang, Xue-Dong; Liu, Xiao-Mo; Sun, Yue; Wang, Gao-Nan; Liu, Yan; Zhou, Yan-Heng

    2016-06-29

    The interplay between stem cells and their extracellular microenvironment is of critical importance to the stem cell-based therapeutics in regenerative medicine. Mineralized collagen is the main component of bone extracellular matrix, but the effect of interfacial properties of mineralized collagen on subsequent cellular behaviors is unclear. This study examined the role of surface chemistry of nanoscale mineralized collagen on human periodontal ligament stem cell (hPDLSC) fate decisions. The intrafibrillarly mineralized collagen (IMC), fabricated by a biomimetic bottom-up approach, showed a bonelike hierarchy with nanohydroxyapatites (HAs) periodically embedded within fibrils. The infrared spectrum of the IMC showed the presence of phosphate, carbonate, amide I and II bands; and infrared mapping displayed uniform and higher spatial distribution of mineralization in the IMC. However, the distribution of the phosphate group differed far from that of the amide I group in the extrafibrillarly mineralized collagen (EMC), in which flowerlike HA clusters randomly depositing around the surface of the fibrils. Moreover, a large quantity of extrafibrillar HAs covered up the C═O stretch and N-H in-plane bend, resulting in substantial reduction of amide I and II bands. Cell experiments demonstrated that the hPDLSCs seeded on the IMC exhibited a highly branched, osteoblast-like polygonal shape with extended pseudopodia and thick stress fiber formation; while cells on the EMC displayed a spindle shape with less branch points and thin actin fibril formation. Furthermore, the biocompatibility of EMC was much lower than that of IMC. Interestingly, even without osteogenic induction, mRNA levels of major osteogenic differentiation genes were highly expressed in the IMC during cultivation time. These data suggest that the IMC with a similar nanotopography and surface chemistry to natural mineralized collagen directs hPDLSCs toward osteoblast differentiation, providing a promising

  19. Surface Chemistry of Nanoscale Mineralized Collagen Regulates Periodontal Ligament Stem Cell Fate.

    PubMed

    Fu, Yu; Liu, Shuai; Cui, Sheng-Jie; Kou, Xiao-Xing; Wang, Xue-Dong; Liu, Xiao-Mo; Sun, Yue; Wang, Gao-Nan; Liu, Yan; Zhou, Yan-Heng

    2016-06-29

    The interplay between stem cells and their extracellular microenvironment is of critical importance to the stem cell-based therapeutics in regenerative medicine. Mineralized collagen is the main component of bone extracellular matrix, but the effect of interfacial properties of mineralized collagen on subsequent cellular behaviors is unclear. This study examined the role of surface chemistry of nanoscale mineralized collagen on human periodontal ligament stem cell (hPDLSC) fate decisions. The intrafibrillarly mineralized collagen (IMC), fabricated by a biomimetic bottom-up approach, showed a bonelike hierarchy with nanohydroxyapatites (HAs) periodically embedded within fibrils. The infrared spectrum of the IMC showed the presence of phosphate, carbonate, amide I and II bands; and infrared mapping displayed uniform and higher spatial distribution of mineralization in the IMC. However, the distribution of the phosphate group differed far from that of the amide I group in the extrafibrillarly mineralized collagen (EMC), in which flowerlike HA clusters randomly depositing around the surface of the fibrils. Moreover, a large quantity of extrafibrillar HAs covered up the C═O stretch and N-H in-plane bend, resulting in substantial reduction of amide I and II bands. Cell experiments demonstrated that the hPDLSCs seeded on the IMC exhibited a highly branched, osteoblast-like polygonal shape with extended pseudopodia and thick stress fiber formation; while cells on the EMC displayed a spindle shape with less branch points and thin actin fibril formation. Furthermore, the biocompatibility of EMC was much lower than that of IMC. Interestingly, even without osteogenic induction, mRNA levels of major osteogenic differentiation genes were highly expressed in the IMC during cultivation time. These data suggest that the IMC with a similar nanotopography and surface chemistry to natural mineralized collagen directs hPDLSCs toward osteoblast differentiation, providing a promising

  20. Sox2-CreER mice are useful for fate mapping of mature, but not neonatal, cochlear supporting cells in hair cell regeneration studies

    PubMed Central

    Walters, Bradley J.; Yamashita, Tetsuji; Zuo, Jian

    2015-01-01

    Studies of hair cell regeneration in the postnatal cochlea rely on fate mapping of supporting cells. Here we characterized a Sox2-CreER knock-in mouse line with two independent reporter mouse strains at neonatal and mature ages. Regardless of induction age, reporter expression was robust, with CreER activity being readily detectable in >85% of supporting cells within the organ of Corti. When induced at postnatal day (P) 28, Sox2-CreER activity was exclusive to supporting cells demonstrating its utility for fate mapping studies beyond this age. However, when induced at P1, Sox2-CreER activity was also detected in >50% of cochlear hair cells, suggesting that Sox2-CreER may not be useful to fate map a supporting cell origin of regenerated hair cells if induced at neonatal ages. Given that this model is currently in use by several investigators for fate mapping purposes, and may be adopted by others in the future, our finding that current protocols are effective for restricting CreER activity to supporting cells at mature but not neonatal ages is both significant and timely. PMID:26108463

  1. A transcription factor network controls cell migration and fate decisions in the developing zebrafish pineal complex

    PubMed Central

    Clanton, Joshua A.; Dean, Benjamin J.; Gamse, Joshua T.

    2016-01-01

    The zebrafish pineal complex consists of four cell types (rod and cone photoreceptors, projection neurons and parapineal neurons) that are derived from a single pineal complex anlage. After specification, parapineal neurons migrate unilaterally away from the rest of the pineal complex whereas rods, cones and projection neurons are non-migratory. The transcription factor Tbx2b is important for both the correct number and migration of parapineal neurons. We find that two additional transcription factors, Flh and Nr2e3, negatively regulate parapineal formation. Flh induces non-migratory neuron fates and limits the extent of parapineal specification, in part by activation of Nr2e3 expression. Tbx2b is positively regulated by Flh, but opposes Flh action during specification of parapineal neurons. Loss of parapineal neuron specification in Tbx2b-deficient embryos can be partially rescued by loss of Nr2e3 or Flh function; however, parapineal migration absolutely requires Tbx2b activity. We conclude that cell specification and migration in the pineal complex are regulated by a network of at least three transcription factors. PMID:27317804

  2. Signaling molecules and pathways regulating the fate of spermatogonial stem cells

    PubMed Central

    He, Zuping; Kokkinaki, Maria; Dym, Martin

    2009-01-01

    Spermatogenesis is the process that involves the division and differentiation of spermatogonial stem cells (SSCs) into mature spermatozoa. SSCs are a subpopulation of type A spermatogonia resting on the basement membrane in the mammalian testis. Self-renewal and differentiation of SSCs are the foundation of normal spermatogenesis, and thus a better understanding of molecular mechanisms and signaling pathways in the SSCs is of paramount importance for the regulation of spermatogenesis and may eventually lead to novel targets for male contraception as well as for gene therapy of male infertility and testicular cancer. Uncovering the molecular mechanisms is also of great interest to a better understanding of SSC aging and for developing novel therapeutic strategies for degenerative diseases in view of the recent work demonstrating the pluripotent potential of the SSC. Progress has recently been made in elucidating the signaling molecules and pathways that determine cell fate decisions of SSCs. In this review, we first address the morphological features, phenotypic characteristics, and the potential of SSCs. And then we focus on the recent advances in defining the key signaling molecules and crucial signaling pathways regulating self-renewal and differentiation of SSCs. The association of aberrant expression of signaling molecules and cascades with abnormal spermatogenesis and testicular cancer are also discussed. Finally we point out potential future directions to pursue in research on signaling pathways of SSCs. PMID:19263492

  3. BMP Receptor 1A Determines the Cell Fate of the Postnatal Growth Plate

    PubMed Central

    Jing, Junjun; Ren, Yinshi; Zong, Zhaowen; Liu, Chuanju; Kamiya, Nobuhiro; Mishina, Yuji; Liu, Ying; Zhou, Xuedong; Feng, Jian Q.

    2013-01-01

    Bone morphogenic proteins (BMPs) are critical for both chondrogenesis and osteogenesis. Previous studies reported that embryos deficient in Bmp receptor (Bmpr)1a or Bmpr1b in cartilage display subtle skeletal defects; however, double mutant embryos develop severe skeletal defects, suggesting a functional redundancy that is essential for early chondrogenesis. In this study, we examined the postnatal role of Bmpr1a in cartilage. In the Bmpr1a conditional knockout (cKO, a cross between Bmpr1a flox and aggrecan-CreERT2 induced by a one-time-tamoxifen injection at birth and harvested at ages of 2, 4, 8 and 20 weeks), there was essentially no long bone growth with little expression of cartilage markers such as SOX9, IHH and glycoproteins. Unexpectedly, the null growth plate was replaced by bone-like tissues, supporting the notions that the progenitor cells in the growth plate, which normally form cartilage, can form other tissues such as bone and fibrous; and that BMPR1A determines the cell fate. A working hypothesis is proposed to explain the vital role of BMPR1A in postnatal chondrogenesis. PMID:24163588

  4. Protein kinase R-like ER kinase and its role in endoplasmic reticulum stress-decided cell fate

    PubMed Central

    Liu, Z; Lv, Y; Zhao, N; Guan, G; Wang, J

    2015-01-01

    Over the past few decades, understandings and evidences concerning the role of endoplasmic reticulum (ER) stress in deciding the cell fate have been constantly growing. Generally, during ER stress, the signal transductions are mainly conducted by three ER stress transducers: protein kinase R-like endoplasmic reticulum kinase (PERK), inositol-requiring kinase 1 (IRE1) and activating transcription factor 6 (ATF6). Consequently, the harmful stimuli from the ER stress transducers induce apoptosis and autophagy, which share several crosstalks and eventually decide the cell fate. The dominance of apoptosis or autophagy induced by ER stress depends on the type and degree of the stimuli. When ER stress is too severe and prolonged, apoptosis is induced to eliminate the damaged cells; however, when stimuli are mild, cell survival is promoted to maintain normal physiological functions by inducing autophagy. Although all the three pathways participate in ER stress-induced apoptosis and autophagy, PERK shows several unique characteristics by interacting with some specific downstream effectors. Notably, there are some preliminary findings on PERK-dependent mechanisms switching autophagy and apoptosis. In this review, we particularly focused on the novel, intriguing and complicated role of PERK in ER stress-decided cell fate, and also discussed more roles of PERK in restoring cellular homeostasis. However, more in-depth knowledge of PERK in the future would facilitate our understanding about many human diseases and benefit in searching for new molecular therapeutic targets. PMID:26225772

  5. YUCCA-mediated auxin biogenesis is required for cell fate transition occurring during de novo root organogenesis in Arabidopsis.

    PubMed

    Chen, Lyuqin; Tong, Jianhua; Xiao, Langtao; Ruan, Ying; Liu, Jingchun; Zeng, Minhuan; Huang, Hai; Wang, Jia-Wei; Xu, Lin

    2016-07-01

    Many plant organs have the ability to regenerate a new plant after detachment or wounding via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, endogenic auxin is essential for the fate transition of regeneration-competent cells to become root founder cells via activation of WUSCHEL-RELATED HOMEOBOX 11 (WOX11). However, the molecular events from leaf explant detachment to auxin-mediated cell fate transition are poorly understood. In this study, we used an assay to determine the concentration of indole-3-acetic acid (IAA) to provide direct evidence that auxin is produced after leaf explant detachment, a process that involves YUCCA (YUC)-mediated auxin biogenesis. Inhibition of YUC prevents expression of WOX11 and fate transition of competent cells, resulting in the blocking of rooting. Further analysis showed that YUC1 and YUC4 act quickly (within 4 hours) in response to wounding after detachment in both light and dark conditions and promote auxin biogenesis in both mesophyll and competent cells, whereas YUC5, YUC8, and YUC9 primarily respond in dark conditions. In addition, YUC2 and YUC6 contribute to rooting by providing a basal auxin level in the leaf. Overall, our study indicates that YUC genes exhibit a division of labour during de novo root organogenesis from leaf explants in response to multiple signals. PMID:27255928

  6. A Pitx2-MicroRNA Pathway Modulates Cell Proliferation in Myoblasts and Skeletal-Muscle Satellite Cells and Promotes Their Commitment to a Myogenic Cell Fate.

    PubMed

    Lozano-Velasco, Estefanía; Vallejo, Daniel; Esteban, Francisco J; Doherty, Chris; Hernández-Torres, Francisco; Franco, Diego; Aránega, Amelia Eva

    2015-09-01

    The acquisition of a proliferating-cell status from a quiescent state as well as the shift between proliferation and differentiation are key developmental steps in skeletal-muscle stem cells (satellite cells) to provide proper muscle regeneration. However, how satellite cell proliferation is regulated is not fully understood. Here, we report that the c-isoform of the transcription factor Pitx2 increases cell proliferation in myoblasts by downregulating microRNA 15b (miR-15b), miR-23b, miR-106b, and miR-503. This Pitx2c-microRNA (miRNA) pathway also regulates cell proliferation in early-activated satellite cells, enhancing Myf5(+) satellite cells and thereby promoting their commitment to a myogenic cell fate. This study reveals unknown functions of several miRNAs in myoblast and satellite cell behavior and thus may have future applications in regenerative medicine. PMID:26055324

  7. T cell fate and clonality inference from single-cell transcriptomes.

    PubMed

    Stubbington, Michael J T; Lönnberg, Tapio; Proserpio, Valentina; Clare, Simon; Speak, Anneliese O; Dougan, Gordon; Teichmann, Sarah A

    2016-04-01

    We developed TraCeR, a computational method to reconstruct full-length, paired T cell receptor (TCR) sequences from T lymphocyte single-cell RNA sequence data. TraCeR links T cell specificity with functional response by revealing clonal relationships between cells alongside their transcriptional profiles. We found that T cell clonotypes in a mouse Salmonella infection model span early activated CD4(+) T cells as well as mature effector and memory cells. PMID:26950746

  8. Glial versus melanocyte cell fate choice: Schwann cell precursors as a cellular origin of melanocytes.

    PubMed

    Adameyko, Igor; Lallemend, Francois

    2010-09-01

    Melanocytes and Schwann cells are derived from the multipotent population of neural crest cells. Although both cell types were thought to be generated through completely distinct pathways and molecular processes, a recent study has revealed that these different cell types are intimately interconnected far beyond previously postulated limits in that they share a common post-neural crest progenitor, i.e. the Schwann cell precursor. This finding raises interesting questions about the lineage relationships of hitherto unrelated cell types such as melanocytes and Schwann cells, and may provide clinical insights into mechanisms of pigmentation disorders and for cancer involving Schwann cells and melanocytes.

  9. Following cell-fate in E. coli after infection by phage lambda.

    PubMed

    Zeng, Lanying; Golding, Ido

    2011-01-01

    The system comprising bacteriophage (phage) lambda and the bacterium E. coli has long served as a paradigm for cell-fate determination. Following the simultaneous infection of the cell by a number of phages, one of two pathways is chosen: lytic (virulent) or lysogenic (dormant). We recently developed a method for fluorescently labeling individual phages, and were able to examine the post-infection decision in real-time under the microscope, at the level of individual phages and cells. Here, we describe the full procedure for performing the infection experiments described in our earlier work. This includes the creation of fluorescent phages, infection of the cells, imaging under the microscope and data analysis. The fluorescent phage is a "hybrid", co-expressing wild- type and YFP-fusion versions of the capsid gpD protein. A crude phage lysate is first obtained by inducing a lysogen of the gpD-EYFP (Enhanced Yellow Fluorescent Protein) phage, harboring a plasmid expressing wild type gpD. A series of purification steps are then performed, followed by DAPI-labeling and imaging under the microscope. This is done in order to verify the uniformity, DNA packaging efficiency, fluorescence signal and structural stability of the phage stock. The initial adsorption of phages to bacteria is performed on ice, then followed by a short incubation at 35°C to trigger viral DNA injection. The phage/bacteria mixture is then moved to the surface of a thin nutrient agar slab, covered with a coverslip and imaged under an epifluorescence microscope. The post-infection process is followed for 4 hr, at 10 min interval. Multiple stage positions are tracked such that ~100 cell infections can be traced in a single experiment. At each position and time point, images are acquired in the phase-contrast and red and green fluorescent channels. The phase-contrast image is used later for automated cell recognition while the fluorescent channels are used to characterize the infection outcome

  10. Fgf20b is required for the ectomesenchymal fate establishment of cranial neural crest cells in zebrafish

    SciTech Connect

    Yamauchi, Hajime; Goto, Mami; Katayama, Mika; Miyake, Ayumi; Itoh, Nobuyuki

    2011-06-17

    Highlights: {yields} The establishment of the ectomesenchymal lineage within the cranial neural crest is of great significance. {yields} Fgf20b knockdown zebrafish embryos showed dysplasticneurocranial and pharyngeal cartilages. {yields} Fgf20b is required for ectomesenchymal fate establishment via the activation of Fgfr1 in zebrafish. -- Abstract: In cranial skeletal development, the establishment of the ectomesenchymal lineage within the cranial neural crest is of great significance. Fgfs are polypeptide growth factors with diverse functions in development and metabolism. Fgf20b knockdown zebrafish embryos showed dysplastic neurocranial and pharyngeal cartilages. Ectomesenchymal cells from cranial neural crest cells were significantly decreased in Fgf20b knockdown embryos, but cranial neural crest cells with a non-ectomesnchymal fate were increased. However, the proliferation and apoptosis of cranial neural crest cells were essentially unchanged. Fgfr1 knockdown embryos also showed dysplastic neurocranial and pharyngeal cartilages. The present findings indicate that Fgf20b is required for ectomesenchymal fate establishment via the activation of Fgfr1 in zebrafish.

  11. Neuronal Cell Fate Specification by the Convergence of Different Spatiotemporal Cues on a Common Terminal Selector Cascade

    PubMed Central

    Rubio-Ferrera, Irene; Millán-Crespo, Irene; Contero-García, Patricia; Bahrampour, Shahrzad

    2016-01-01

    Specification of the myriad of unique neuronal subtypes found in the nervous system depends upon spatiotemporal cues and terminal selector gene cascades, often acting in sequential combinatorial codes to determine final cell fate. However, a specific neuronal cell subtype can often be generated in different parts of the nervous system and at different stages, indicating that different spatiotemporal cues can converge on the same terminal selectors to thereby generate a similar cell fate. However, the regulatory mechanisms underlying such convergence are poorly understood. The Nplp1 neuropeptide neurons in the Drosophila ventral nerve cord can be subdivided into the thoracic-ventral Tv1 neurons and the dorsal-medial dAp neurons. The activation of Nplp1 in Tv1 and dAp neurons depends upon the same terminal selector cascade: col>ap/eya>dimm>Nplp1. However, Tv1 and dAp neurons are generated by different neural progenitors (neuroblasts) with different spatiotemporal appearance. Here, we find that the same terminal selector cascade is triggered by Kr/pdm>grn in dAp neurons, but by Antp/hth/exd/lbe/cas in Tv1 neurons. Hence, two different spatiotemporal combinations can funnel into a common downstream terminal selector cascade to determine a highly related cell fate. PMID:27148744

  12. Whi5 phosphorylation embedded in the G1/S network dynamically controls critical cell size and cell fate

    PubMed Central

    Palumbo, Pasquale; Vanoni, Marco; Cusimano, Valerio; Busti, Stefano; Marano, Francesca; Manes, Costanzo; Alberghina, Lilia

    2016-01-01

    In budding yeast, overcoming of a critical size to enter S phase and the mitosis/mating switch—two central cell fate events—take place in the G1 phase of the cell cycle. Here we present a mathematical model of the basic molecular mechanism controlling the G1/S transition, whose major regulatory feature is multisite phosphorylation of nuclear Whi5. Cln3–Cdk1, whose nuclear amount is proportional to cell size, and then Cln1,2–Cdk1, randomly phosphorylate both decoy and functional Whi5 sites. Full phosphorylation of functional sites releases Whi5 inhibitory activity, activating G1/S transcription. Simulation analysis shows that this mechanism ensures coherent release of Whi5 inhibitory action and accounts for many experimentally observed properties of mitotically growing or conjugating G1 cells. Cell cycle progression and transcriptional analyses of a Whi5 phosphomimetic mutant verify the model prediction that coherent transcription of the G1/S regulon and ensuing G1/S transition requires full phosphorylation of Whi5 functional sites. PMID:27094800

  13. Whi5 phosphorylation embedded in the G1/S network dynamically controls critical cell size and cell fate.

    PubMed

    Palumbo, Pasquale; Vanoni, Marco; Cusimano, Valerio; Busti, Stefano; Marano, Francesca; Manes, Costanzo; Alberghina, Lilia

    2016-01-01

    In budding yeast, overcoming of a critical size to enter S phase and the mitosis/mating switch--two central cell fate events--take place in the G1 phase of the cell cycle. Here we present a mathematical model of the basic molecular mechanism controlling the G1/S transition, whose major regulatory feature is multisite phosphorylation of nuclear Whi5. Cln3-Cdk1, whose nuclear amount is proportional to cell size, and then Cln1,2-Cdk1, randomly phosphorylate both decoy and functional Whi5 sites. Full phosphorylation of functional sites releases Whi5 inhibitory activity, activating G1/S transcription. Simulation analysis shows that this mechanism ensures coherent release of Whi5 inhibitory action and accounts for many experimentally observed properties of mitotically growing or conjugating G1 cells. Cell cycle progression and transcriptional analyses of a Whi5 phosphomimetic mutant verify the model prediction that coherent transcription of the G1/S regulon and ensuing G1/S transition requires full phosphorylation of Whi5 functional sites. PMID:27094800

  14. Lipid body formation plays a central role in cell fate determination during developmental differentiation of Myxococcus xanthus.

    PubMed

    Hoiczyk, Egbert; Ring, Michael W; McHugh, Colleen A; Schwär, Gertrud; Bode, Edna; Krug, Daniel; Altmeyer, Matthias O; Lu, Jeff Zhiqiang; Bode, Helge B

    2009-10-01

    Cell differentiation is widespread during the development of multicellular organisms, but rarely observed in prokaryotes. One example of prokaryotic differentiation is the gram-negative bacterium Myxococcus xanthus. In response to starvation, this gliding bacterium initiates a complex developmental programme that results in the formation of spore-filled fruiting bodies. How the cells metabolically support the necessary complex cellular differentiation from rod-shaped vegetative cells into spherical spores is unknown. Here, we present evidence that intracellular lipid bodies provide the necessary metabolic fuel for the development of spores. Formed at the onset of starvation, these lipid bodies gradually disappear until they are completely used up by the time the cells have become mature spores. Moreover, it appears that lipid body formation in M. xanthus is an important initial step indicating cell fate during differentiation. Upon starvation, two subpopulations of cells occur: cells that form lipid bodies invariably develop into spores, while cells that do not form lipid bodies end up becoming peripheral rods, which are cells that lack signs of morphological differentiation and stay in a vegetative-like state. These data indicate that lipid bodies not only fuel cellular differentiation but that their formation represents the first known morphological sign indicating cell fate during differentiation. PMID:19788540

  15. Lipid body formation plays a central role in cell fate determination during developmental differentiation of Myxococcus xanthus

    PubMed Central

    Ring, Michael W.; McHugh, Colleen A.; Schwär, Gertrud; Bode, Edna; Krug, Daniel; Altmeyer, Matthias O.; Lu, Jeff Zhiqiang

    2010-01-01

    Summary Cell differentiation is widespread during the development of multicellular organisms, but rarely observed in prokaryotes. One example of prokaryotic differentiation is the Gramnegative bacterium Myxococcus xanthus. In response to starvation, this gliding bacterium initiates a complex developmental program that results in the formation of spore-filled fruiting bodies. How the cells metabolically support the necessary complex cellular differentiation from rod-shaped vegetative cells into spherical spores is unknown. Here, we present evidence that intra-cellular lipid bodies provide the necessary metabolic fuel for the development of spores. Formed at the onset of starvation, these lipid bodies gradually disappear until they are completely used up by the time the cells have become mature spores. Moreover, it appears that lipid body formation in M. xanthus is an important initial step indicating cell fate during differentiation. Upon starvation, two subpopulations of cells occur: cells that form lipid bodies invariably develop into spores, while cells that do not form lipid bodies end up becoming peripheral rods, which are cells that lack signs of morphological differentiation and stay in a vegetative-like state. These data indicate that lipid bodies not only fuel cellular differentiation but that their formation represents the first known morphological sign indicating cell fate during differentiation. PMID:19788540

  16. The dynamic interplay between a cell fate determinant and a lysozyme homolog drives the asymmetric division cycle of Caulobacter crescentus

    PubMed Central

    Radhakrishnan, Sunish Kumar; Thanbichler, Martin; Viollier, Patrick H.

    2008-01-01

    Caulobacter crescentus divides asymmetrically into a swarmer cell and a stalked cell, a process that is governed by the imbalance in phosphorylated levels of the DivK cell fate determinant in the two cellular compartments. The asymmetric polar localization of the DivJ kinase results in its specific inheritance in the stalked daughter cell where it phosphorylates DivK. The mechanism for the polar positioning of DivJ is poorly understood. SpmX, an uncharacterized lysozyme homolog, is shown here to control DivJ localization and activation. In the absence of SpmX, DivJ is delocalized and dysfunctional, resulting in developmental defects caused by an insufficiency in phospho-DivK. While SpmX stimulates DivK phosphorylation in the stalked cell, unphosphorylated DivK in the swarmer cell activates an intricate transcriptional cascade that leads to the production of the spmX message. This event primes the swarmer cell for the impending transition into a stalked cell, a transition that is sparked by the abrupt accumulation and localization of SpmX to the future stalked cell pole. Localized SpmX then recruits and stimulates DivJ, and the resulting phospho-DivK implements the stalked cell fate. The dynamic interplay between SpmX and DivK is at the heart of the molecular circuitry that sustains the Caulobacter developmental cycle. PMID:18198338

  17. Muscle cell fate choice requires the T-box transcription factor midline in Drosophila.

    PubMed

    Kumar, Ram P; Dobi, Krista C; Baylies, Mary K; Abmayr, Susan M

    2015-03-01

    Drosophila Midline (Mid) is an ortholog of vertebrate Tbx20, which plays roles in the developing heart, migrating cranial motor neurons, and endothelial cells. Mid functions in cell-fate specification and differentiation of tissues that include the ectoderm, cardioblasts, neuroblasts, and egg chambers; however, a role in the somatic musculature has not been described. We identified mid in genetic and molecular screens for factors contributing to somatic muscle morphogenesis. Mid is expressed in founder cells (FCs) for several muscle fibers, and functions cooperatively with the T-box protein H15 in lateral oblique muscle 1 and the segment border muscle. Mid is particularly important for the specification and development of the lateral transverse (LT) muscles LT3 and LT4, which arise by asymmetric division of a single muscle progenitor. Mid is expressed in this progenitor and its two sibling FCs, but is maintained only in the LT4 FC. Both muscles were frequently missing in mid mutant embryos, and LT4-associated expression of the transcription factor Krüppel (Kr) was lost. When present, LT4 adopted an LT3-like morphology. Coordinately, mid misexpression caused LT3 to adopt an LT4-like morphology and was associated with ectopic Kr expression. From these data, we concluded that mid functions first in the progenitor to direct development of LT3 and LT4, and later in the FCs to influence whichever of these differentiation profiles is selected. Mid is the first T-box factor shown to influence LT3 and LT4 muscle identity and, along with the T-box protein Optomotor-blind-related-gene 1 (Org-1), is representative of a new class of transcription factors in muscle specification.

  18. Arabidopsis BIRD Zinc Finger Proteins Jointly Stabilize Tissue Boundaries by Confining the Cell Fate Regulator SHORT-ROOT and Contributing to Fate Specification

    PubMed Central

    Long, Yuchen; Smet, Wouter; Cruz-Ramírez, Alfredo; Castelijns, Bas; de Jonge, Wim; Mähönen, Ari Pekka; Bouchet, Benjamin P.; Perez, Gabino Sanchez; Akhmanova, Anna; Scheres, Ben; Blilou, Ikram

    2015-01-01

    Plant cells cannot rearrange their positions; therefore, sharp tissue boundaries must be accurately programmed. Movement of the cell fate regulator SHORT-ROOT from the stele to the ground tissue has been associated with transferring positional information across tissue boundaries. The zinc finger BIRD protein JACKDAW has been shown to constrain SHORT-ROOT movement to a single layer, and other BIRD family proteins were postulated to counteract JACKDAW’s role in restricting SHORT-ROOT action range. Here, we report that regulation of SHORT-ROOT movement requires additional BIRD proteins whose action is critical for the establishment and maintenance of the boundary between stele and ground tissue. We show that BIRD proteins act in concert and not in opposition. The exploitation of asymmetric redundancies allows the separation of two BIRD functions: constraining SHORT-ROOT spread through nuclear retention and transcriptional regulation of key downstream SHORT-ROOT targets, including SCARECROW and CYCLIND6. Our data indicate that BIRD proteins promote formative divisions and tissue specification in the Arabidopsis thaliana root meristem ground tissue by tethering and regulating transcriptional competence of SHORT-ROOT complexes. As a result, a tissue boundary is not “locked in” after initial patterning like in many animal systems, but possesses considerable developmental plasticity due to continuous reliance on mobile transcription factors. PMID:25829440

  19. p53 integrates host defense and cell fate during bacterial pneumonia

    PubMed Central

    Madenspacher, Jennifer H.; Azzam, Kathleen M.; Gowdy, Kymberly M.; Malcolm, Kenneth C.; Nick, Jerry A.; Dixon, Darlene; Aloor, Jim J.; Draper, David W.; Guardiola, John J.; Shatz, Maria; Menendez, Daniel; Lowe, Julie; Lu, Jun; Bushel, Pierre; Li, Leping; Merrick, B. Alex; Resnick, Michael A.

    2013-01-01

    Cancer and infection are predominant causes of human mortality and derive, respectively, from inadequate genomic and host defenses against environmental agents. The transcription factor p53 plays a central role in human tumor suppression. Despite its expression in immune cells and broad responsiveness to stressors, it is virtually unknown whether p53 regulates host defense against infection. We report that the lungs of naive p53−/− mice display genome-wide induction of NF-κB response element–enriched proinflammatory genes, suggestive of type 1 immune priming. p53-null and p53 inhibitor–treated mice clear Gram-negative and -positive bacteria more effectively than controls after intrapulmonary infection. This is caused, at least in part, by cytokines produced by an expanded population of apoptosis-resistant, TLR-hyperresponsive alveolar macrophages that enhance airway neutrophilia. p53−/− neutrophils, in turn, display heightened phagocytosis, Nox-dependent oxidant generation, degranulation, and bacterial killing. p53 inhibition boosts bacterial killing by mouse neutrophils and oxidant generation by human neutrophils. Despite enhanced bacterial clearance, infected p53−/− mice suffer increased mortality associated with aggravated lung injury. p53 thus modulates host defense through regulating microbicidal function and fate of phagocytes, revealing a fundamental link between defense of genome and host during environmental insult. PMID:23630228

  20. Modifications to glucocorticoid and progesterone receptors alter cell fate in breast cancer.

    PubMed

    Leehy, Katherine A; Regan Anderson, Tarah M; Daniel, Andrea R; Lange, Carol A; Ostrander, Julie H

    2016-04-01

    Steroid hormone receptors (SRs) are heavily posttranslationally modified by the reversible addition of a variety of molecular moieties, including phosphorylation, acetylation, methylation, SUMOylation, and ubiquitination. These rapid and dynamic modifications may be combinatorial and interact (i.e. may be sequential, complement, or oppose each other), creating a vast array of uniquely modified receptor subspecies that allow for diverse receptor behaviors that enable highly sensitive and context-dependent hormone action. For example, in response to hormone or growth factor membrane-initiated signaling events, posttranslational modifications (PTMs) to SRs alter protein-protein interactions that govern the complex process of promoter or gene-set selection coupled to transcriptional repression or activation. Unique phosphorylation events allow SRs to associate or disassociate with specific cofactors that may include pioneer factors and other tethering partners, which specify the resulting transcriptome and ultimately change cell fate. The impact of PTMs on SR action is particularly profound in the context of breast tumorigenesis, in which frequent alterations in growth factor-initiated signaling pathways occur early and act as drivers of breast cancer progression toward endocrine resistance. In this article, with primary focus on breast cancer relevance, we review the mechanisms by which PTMs, including reversible phosphorylation events, regulate the closely related SRs, glucocorticoid receptor and progesterone receptor, allowing for precise biological responses to ever-changing hormonal stimuli.

  1. Genome-Wide Analysis Reveals a Major Role in Cell Fate Maintenance and an Unexpected Role in Endoreduplication for the Drosophila FoxA Gene Fork Head

    PubMed Central

    Maruyama, Rika; Grevengoed, Elizabeth; Stempniewicz, Peter; Andrew, Deborah J.

    2011-01-01

    Transcription factors drive organogenesis, from the initiation of cell fate decisions to the maintenance and implementation of these decisions. The Drosophila embryonic salivary gland provides an excellent platform for unraveling the underlying transcriptional networks of organ development because Drosophila is relatively unencumbered by significant genetic redundancy. The highly conserved FoxA family transcription factors are essential for various aspects of organogenesis in all animals that have been studied. Here, we explore the role of the single Drosophila FoxA protein Fork head (Fkh) in salivary gland organogenesis using two genome-wide strategies. A large-scale in situ hybridization analysis reveals a major role for Fkh in maintaining the salivary gland fate decision and controlling salivary gland physiological activity, in addition to its previously known roles in morphogenesis and survival. The majority of salivary gland genes (59%) are affected by fkh loss, mainly at later stages of salivary gland development. We show that global expression of Fkh cannot drive ectopic salivary gland formation. Thus, unlike the worm FoxA protein PHA-4, Fkh does not function to specify cell fate. In addition, Fkh only indirectly regulates many salivary gland genes, which is also distinct from the role of PHA-4 in organogenesis. Our microarray analyses reveal unexpected roles for Fkh in blocking terminal differentiation and in endoreduplication in the salivary gland and in other Fkh-expressing embryonic tissues. Overall, this study demonstrates an important role for Fkh in determining how an organ preserves its identity throughout development and provides an alternative paradigm for how FoxA proteins function in organogenesis. PMID:21698206

  2. Essential role of Bmp signaling and its positive feedback loop in the early cell fate evolution of chordates.

    PubMed

    Kozmikova, Iryna; Candiani, Simona; Fabian, Peter; Gurska, Daniela; Kozmik, Zbynek

    2013-10-15

    In chordates, early separation of cell fate domains occurs prior to the final specification of ectoderm to neural and non-neural as well as mesoderm to dorsal and ventral during development. Maintaining such division with the establishment of an exact border between the domains is required for the formation of highly differentiated structures such as neural tube and notochord. We hypothesized that the key condition for efficient cell fate separation in a chordate embryo is the presence of a positive feedback loop for Bmp signaling within the gene regulatory network (GRN), underlying early axial patterning. Here, we therefore investigated the role of Bmp signaling in axial cell fate determination in amphioxus, the basal chordate possessing a centralized nervous system. Pharmacological inhibition of Bmp signaling induces dorsalization of amphioxus embryos and expansion of neural plate markers, which is consistent with an ancestral role of Bmp signaling in chordate axial patterning and neural plate formation. Furthermore, we provided evidence for the presence of the positive feedback loop within the Bmp signaling network of amphioxus. Using mRNA microinjections we found that, in contrast to vertebrate Vent genes, which promote the expression of Bmp4, amphioxus Vent1 is likely not responsible for activation of cephalochordate ortholog Bmp2/4. Cis-regulatory analysis of amphioxus Bmp2/4, Admp and Chordin promoters in medaka embryos revealed remarkable conservation of the gene regulatory information between vertebrates and basal chordates. Our data suggest that emergence of a positive feedback loop within the Bmp signaling network may represent a key molecular event in the evolutionary history of the chordate cell fate determination.

  3. Essential role of Bmp signaling and its positive feedback loop in the early cell fate evolution of chordates.

    PubMed

    Kozmikova, Iryna; Candiani, Simona; Fabian, Peter; Gurska, Daniela; Kozmik, Zbynek

    2013-10-15

    In chordates, early separation of cell fate domains occurs prior to the final specification of ectoderm to neural and non-neural as well as mesoderm to dorsal and ventral during development. Maintaining such division with the establishment of an exact border between the domains is required for the formation of highly differentiated structures such as neural tube and notochord. We hypothesized that the key condition for efficient cell fate separation in a chordate embryo is the presence of a positive feedback loop for Bmp signaling within the gene regulatory network (GRN), underlying early axial patterning. Here, we therefore investigated the role of Bmp signaling in axial cell fate determination in amphioxus, the basal chordate possessing a centralized nervous system. Pharmacological inhibition of Bmp signaling induces dorsalization of amphioxus embryos and expansion of neural plate markers, which is consistent with an ancestral role of Bmp signaling in chordate axial patterning and neural plate formation. Furthermore, we provided evidence for the presence of the positive feedback loop within the Bmp signaling network of amphioxus. Using mRNA microinjections we found that, in contrast to vertebrate Vent genes, which promote the expression of Bmp4, amphioxus Vent1 is likely not responsible for activation of cephalochordate ortholog Bmp2/4. Cis-regulatory analysis of amphioxus Bmp2/4, Admp and Chordin promoters in medaka embryos revealed remarkable conservation of the gene regulatory information between vertebrates and basal chordates. Our data suggest that emergence of a positive feedback loop within the Bmp signaling network may represent a key molecular event in the evolutionary history of the chordate cell fate determination. PMID:23933491

  4. A Two-Step Mechanism for Cell Fate Decision by Coordination of Nuclear and Mitochondrial p53 Activities

    PubMed Central

    Tian, Xiao-Jun; Liu, Feng; Zhang, Xiao-Peng; Li, Jun; Wang, Wei

    2012-01-01

    The tumor suppressor p53 has a crucial role in the DNA damage response. Here, we proposed an integrated model of the p53 network and explored how the nuclear and mitochondrial p53 pathways are coordinated to determine cell fates after -irradiation in radiosensitive tissues. Using numerical simulations, we found that depending on the extent of DNA damage, cells may survive, commit apoptosis after cell cycle arrest, or undergo apoptosis soon after irradiation. There exists a large cell-to-cell variability in outcome because of stochasticity in the generation and repair of DNA damage as well as cellular heterogeneity. At the cell population level, there occur two waves of apoptosis: a fast wave mediated by mitochondrial p53 within three hours postirradiation, and a slow wave mediated by nuclear p53 after eight hours postirradiation. Thus, we propose a two-step mechanism for cell fate decision. The first step is to decide whether DNA damage is severe enough to trigger apoptosis directly through the mitochondrial p53 pathway, while the second step is to determine whether the damage is fixed after cell cycle arrest. Such a mechanism may represent an efficient and reliable control mode, avoiding unnecessary death or greatly promoting the execution of apoptosis. It was also demonstrated that nuclear p53 can inhibit the pro-apoptotic activity of mitochondrial p53 by transactivating p21, and Mdm2 can facilitate apoptosis by promoting the mono-ubiquitination of p53. These results are either in good agreement with experimental observations or experimentally testable. Our work suggests that both the transcription-independent and -dependent p53 activities are indispensable for a reliable choice of cell fate and also provides clues to therapeutic manipulation of the p53 pathway in cancer treatment. PMID:22679490

  5. Notch-mediated patterning and cell fate allocation of pancreatic progenitor cells

    PubMed Central

    Afelik, Solomon; Qu, Xiaoling; Hasrouni, Edy; Bukys, Michael A.; Deering, Tye; Nieuwoudt, Stephan; Rogers, William; MacDonald, Raymond J.; Jensen, Jan

    2012-01-01

    Early pancreatic morphogenesis is characterized by the transformation of an uncommitted pool of pancreatic progenitor cells into a branched pancreatic epithelium that consists of ‘tip’ and ‘trunk’ domains. These domains have distinct molecular signatures and differentiate into distinct pancreatic cell lineages. Cells at the branched tips of the epithelium develop into acinar cells, whereas cells in the trunk subcompartment differentiate into endocrine and duct cells. Recent genetic analyses have highlighted the role of key transcriptional regulators in the specification of these subcompartments. Here, we analyzed in mice the role of Notch signaling in the patterning of multipotent pancreatic progenitor cells through mosaic overexpression of a Notch signaling antagonist, dominant-negative mastermind-like 1, resulting in a mixture of wild-type and Notch-suppressed pancreatic progenitor cells. We find that attenuation of Notch signaling has pronounced patterning effects on multipotent pancreatic progenitor cells prior to terminal differentiation. Relative to the wild-type cells, the Notch-suppressed cells lose trunk marker genes and gain expression of tip marker genes. The Notch-suppressed cells subsequently differentiate into acinar cells, whereas duct and endocrine populations are formed predominantly from the wild-type cells. Mechanistically, these observations could be explained by a requirement of Notch for the expression of the trunk determination gene Nkx6.1. This was supported by the finding of direct binding of RBP-jκ to the Nkx6.1 proximal promoter. PMID:22461559

  6. Defined spatiotemporal features of RAS-ERK signals dictate cell fate in MCF-7 mammary epithelial cells

    PubMed Central

    Herrero, Ana; Casar, Berta; Colón-Bolea, Paula; Agudo-Ibáñez, Lorena; Crespo, Piero

    2016-01-01

    Signals conveyed through the RAS-ERK pathway are essential for the determination of cell fate. It is well established that signal variability is achieved in the different microenvironments in which signals unfold. It is also known that signal duration is critical for decisions concerning cell commitment. However, it is unclear how RAS-ERK signals integrate time and space in order to elicit a given biological response. To investigate this, we used MCF-7 cells, in which EGF-induced transient ERK activation triggers proliferation, whereas sustained ERK activation in response to heregulin leads to adipocytic differentiation. We found that both proliferative and differentiating signals emanate exclusively from plasma membrane–disordered microdomains. Of interest, the EGF signal can be transformed into a differentiating stimulus by HRAS overexpression, which prolongs ERK activation, but only if HRAS localizes at disordered membrane. On the other hand, HRAS signals emanating from the Golgi complex induce apoptosis and can prevent heregulin-induced differentiation. Our results indicate that within the same cellular context, RAS can exert different, even antagonistic, effects, depending on its sublocalization. Thus cell destiny is defined by the ability of a stimulus to activate RAS at the appropriate sublocalization for an adequate period while avoiding switching on opposing RAS signals. PMID:27099370

  7. Glycobiology of cell death: when glycans and lectins govern cell fate

    PubMed Central

    Lichtenstein, R G; Rabinovich, G A

    2013-01-01

    Although one typically thinks of carbohydrates as associated with cell growth and viability, glycosylation also has an integral role in many processes leading to cell death. Glycans, either alone or complexed with glycan-binding proteins, can deliver intracellular signals or control extracellular processes that promote initiation, execution and resolution of cell death programs. Herein, we review the role of glycans and glycan-binding proteins as essential components of the cell death machinery during physiologic and pathologic settings. PMID:23703323

  8. The relationship between cell size and cell fate in Volvox carteri

    PubMed Central

    1993-01-01

    In Volvox carteri development, visibly asymmetric cleavage divisions set apart large embryonic cells that will become asexual reproductive cells (gonidia) from smaller cells that will produce terminally differentiated somatic cells. Three mechanisms have been proposed to explain how asymmetric division leads to cell specification in Volvox: (a) by a direct effect of cell size (or a property derived from it) on cell specification, (b) by segregation of a cytoplasmic factor resembling germ plasm into large cells, and (c) by a combined effect of differences in cytoplasmic quality and cytoplasmic quantity. In this study a variety of V. carteri embryos with genetically and experimentally altered patterns of development were examined in an attempt to distinguish among these hypotheses. No evidence was found for regionally specialized cytoplasm that is essential for gonidial specification. In all cases studied, cells with a diameter > approximately 8 microns at the end of cleavage--no matter where or how these cells had been produced in the embryo--developed as gonidia. Instructive observations in this regard were obtained by three different experimental interventions. (a) When heat shock was used to interrupt cleavage prematurely, so that presumptive somatic cells were left much larger than they normally would be at the end of cleavage, most cells differentiated as gonidia. This result was obtained both with wild-type embryos that had already divided asymmetrically (and should have segregated any cytoplasmic determinants involved in cell specification) and with embryos of a mutant that normally produces only somatic cells. (b) When individual wild-type blastomeres were isolated at the 16-cell stage, both the anterior blastomeres that normally produce two gonidia each and the posterior blastomeres that normally produce no gonidia underwent modified cleavage patterns and each produced an average of one large cell that developed as a gonidium. (c) When large cells were

  9. Mesenchymal condensation-dependent accumulation of collagen VI stabilizes organ-specific cell fates during embryonic tooth formation

    PubMed Central

    Mammoto, Tadanori; Mammoto, Akiko; Jiang, Amanda; Jiang, Elisabeth; Hashmi, Basma; Ingber, Donald E.

    2015-01-01

    Background Mechanical compression of cells during mesenchymal condensation triggers cells to undergo odontogenic differentiation during tooth organ formation in the embryo. However, the mechanism by which cell compaction is stabilized over time to ensure correct organ specific cell fate switching remains unknown. Results Here, we show that mesenchymal cell compaction induces accumulation of collagen VI in the extracellular matrix (ECM), which physically stabilizes compressed mesenchymal cell shapes and ensures efficient organ-specific cell fate switching during tooth organ development. Mechanical induction of collagen VI deposition is mediated by signaling through the actin-p38MAPK-SP1 pathway, and the ECM scaffold is stabilized by lysyl oxidase (LOX) in the condensing mesenchyme. Moreover, perturbation of synthesis or cross-linking of collagen VI alters the size of the condensation in vivo. Conclusions These findings suggest that the odontogenic differentiation process that is induced by cell compaction during mesenchymal condensation is stabilized and sustained through mechanically-regulated production of collagen VI within the mesenchymal ECM. PMID:25715693

  10. Arid3a is essential to execution of the first cell fate decision via direct embryonic and extraembryonic transcriptional regulation

    PubMed Central

    Rhee, Catherine; Lee, Bum-Kyu; Beck, Samuel; Anjum, Azeen; Cook, Kendra R.; Popowski, Melissa

    2014-01-01

    Despite their origin from the inner cell mass, embryonic stem (ES) cells undergo differentiation to the trophectoderm (TE) lineage by repression of the ES cell master regulator Oct4 or activation of the TE master regulator Caudal-type homeobox 2 (Cdx2). In contrast to the in-depth studies of ES cell self-renewal and pluripotency, few TE-specific regulators have been identified, thereby limiting our understanding of mechanisms underlying the first cell fate decision. Here we show that up-regulation and nuclear entry of AT-rich interactive domain 3a (Arid3a) drives TE-like transcriptional programs in ES cells, maintains trophoblast stem (TS) cell self-renewal, and promotes further trophoblastic differentiation both upstream and independent of Cdx2. Accordingly, Arid3a−/− mouse post-implantation placental development is severely impaired, resulting in early embryonic death. We provide evidence that Arid3a directly activates TE-specific and trophoblast lineage-specific genes while directly repressing pluripotency genes via differential regulation of epigenetic acetylation or deacetylation. Our results identify Arid3a as a critical regulator of TE and placental development through execution of the commitment and differentiation phases of the first cell fate decision. PMID:25319825

  11. Hippocampal cell fate regulation by chronic cocaine during periods of adolescent vulnerability: Consequences of cocaine exposure during adolescence on behavioral despair in adulthood.

    PubMed

    García-Cabrerizo, R; Keller, B; García-Fuster, M J

    2015-09-24

    Given that adolescence represents a critical moment for shaping adult behavior and may predispose to disease vulnerability later in life, the aim of this study was to find a vulnerable period during adolescence in which hippocampal cell fate regulation was altered by cocaine exposure, and to evaluate the long-term consequences of a cocaine experience during adolescence in affecting hippocampal plasticity and behavioral despair in adulthood. Study I: Male rats were treated with cocaine (15mg/kg, i.p.) or saline for 7 consecutive days during adolescence (early post-natal day (PND) 33-39, mid PND 40-46, late PND 47-53). Hippocampal plasticity (i.e., cell fate regulation, cell genesis) was evaluated 24h after the last treatment dose during the course of adolescence (PND 40, PND 47, PND 54). Study II: The consequences of cocaine exposure during adolescence (PND 33-39 or PND 33-46; 7 or 14days) were measured in adulthood at the behavioral (i.e., forced swim test, PND 62-63) and molecular (hippocampal cell markers, PND 64) levels. Chronic cocaine during early adolescence dysregulated FADD forms only in the hippocampus (HC), as compared to other brain regions, and during mid adolescence, impaired cell proliferation (Ki-67) and increased PARP-1 cleavage (a cell death maker) in the HC. Interestingly, chronic cocaine exposure during adolescence did not alter the time adult rats spent immobile in the forced swim test. These results suggest that this paradigm of chronic cocaine administration during adolescence did not contribute to the later manifestation of behavioral despair (i.e., one pro-depressive symptom) as measured by the forced swim test in adulthood.

  12. Hippocampal cell fate regulation by chronic cocaine during periods of adolescent vulnerability: Consequences of cocaine exposure during adolescence on behavioral despair in adulthood.

    PubMed

    García-Cabrerizo, R; Keller, B; García-Fuster, M J

    2015-09-24

    Given that adolescence represents a critical moment for shaping adult behavior and may predispose to disease vulnerability later in life, the aim of this study was to find a vulnerable period during adolescence in which hippocampal cell fate regulation was altered by cocaine exposure, and to evaluate the long-term consequences of a cocaine experience during adolescence in affecting hippocampal plasticity and behavioral despair in adulthood. Study I: Male rats were treated with cocaine (15mg/kg, i.p.) or saline for 7 consecutive days during adolescence (early post-natal day (PND) 33-39, mid PND 40-46, late PND 47-53). Hippocampal plasticity (i.e., cell fate regulation, cell genesis) was evaluated 24h after the last treatment dose during the course of adolescence (PND 40, PND 47, PND 54). Study II: The consequences of cocaine exposure during adolescence (PND 33-39 or PND 33-46; 7 or 14days) were measured in adulthood at the behavioral (i.e., forced swim test, PND 62-63) and molecular (hippocampal cell markers, PND 64) levels. Chronic cocaine during early adolescence dysregulated FADD forms only in the hippocampus (HC), as compared to other brain regions, and during mid adolescence, impaired cell proliferation (Ki-67) and increased PARP-1 cleavage (a cell death maker) in the HC. Interestingly, chronic cocaine exposure during adolescence did not alter the time adult rats spent immobile in the forced swim test. These results suggest that this paradigm of chronic cocaine administration during adolescence did not contribute to the later manifestation of behavioral despair (i.e., one pro-depressive symptom) as measured by the forced swim test in adulthood. PMID:26215918

  13. Epidermal stem cells: markers, patterning and the control of stem cell fate.

    PubMed Central

    Watt, F M

    1998-01-01

    Within the epidermis, proliferation takes place in the basal layer of keratinocytes that are attached to an underlying basement membrane. Cells that leave the basal layer undergo terminal differentiation as they move towards the tissue surface. The basal layer contains two types of proliferative keratinocyte: stem cells, which have unlimited self-renewal capacity, and transit amplifying cells, those daughters of stem cells that are destined to withdraw from the cell cycle and terminally differentiate after a few rounds of division. Stem cells express higher levels of the beta 1-integrin family of extracellular matrix receptors than transit amplifying cells and this can be used to isolate each subpopulation of keratinocyte and to determine its location within the epidermis. Variation in the levels of E-cadherin, beta-catenin and plakoglobin within the basal layer suggests that stem cells may also differ from transit amplifying cells in intercellular adhesiveness. Stem cells have a patterned distribution within the epidermal basal layer and patterning is subject to autoregulation. Constitutive expression of the transcription factor c-Myc promotes terminal differentiation by driving keratinocytes from the stem cell compartment into the transit amplifying compartment. PMID:9684280

  14. A new fate for old cells: brush cells and related elements

    PubMed Central

    Sbarbati, A; Osculati, F

    2005-01-01

    Over the past 50 years, hundreds of studies have described those cells that are characterized by a brush of rigid apical microvilli with long rootlets, and which are found in the digestive and respiratory apparatuses. These cells have been given names such as brush cells, tuft cells, fibrillovesicular cells, multivesicular cells and caveolated cells. More recently, it has been realized that all these elements may represent a single cell type, probably with a chemosensory role, even if other functions (e.g. secretory or absorptive) seem to be possible. Very recent developments have permitted a partial definition of the chemical code characterizing these elements, revealing the presence of molecules involved in chemoreceptorial cell signalling. A molecular cascade, similar to those characterizing the gustatory epithelium, seems to be present in these elements. These new data suggest that these elements can be considered solitary chemosensory cells with the presence of the apical ‘brush’ as an inconsistent feature. They seem to comprise a diffuse chemosensory system that covers large areas (probably the whole digestive and respiratory apparatuses) with analogies to chemosensory systems described in aquatic vertebrates. PMID:15817103

  15. Physical parameters affecting living cells in space

    NASA Astrophysics Data System (ADS)

    Langbein, Dieter

    The question is posed: Why does a living cell react to the absence of gravity? What sensors may it have? Does it note pressure, sedimentation, convection, or other parameters? If somewhere in a liquid volume sodium ions are replaced by potassium ions, the density of the liquid changes locally: the heavier regions sink, the lighter regions rise. This may contribute to species transport, to the metabolism. Under microgravity this mechanism is strongly reduced. On the other hand, other reasons for convection like thermal and solutal interface convection are left. Do they affect species transport? Another important effect of gravity is the hydrostatic pressure. On the macroscopic side, the pressure between our head and feet changes by 0.35 atmospheres. On the microscopic level the hydrostatic pressure on the upper half of a cell membrane is lower than on the lower half. This, by affecting the ion transport through the membrane, may change the surrounding electric potential. It has been suggested to be one of the reasons for graviperception. Following the discussion of these and other effects possibly important in life sciences in space, an order of magnitude analysis of the residual accelerations tolerable during experiments in materials sciences is outlined. In the field of life sciences only rough estimates are available at present.

  16. miRNA-mediated feedback inhibition of JAK/STAT morphogen signalling establishes a cell fate threshold.

    PubMed

    Yoon, Wan Hee; Meinhardt, Hans; Montell, Denise J

    2011-09-01

    Patterns of cell fates generated by morphogens are critically important for normal development; however, the mechanisms by which graded morphogen signals are converted into all-or-none cell fate responses are incompletely understood. In the Drosophila ovary, high and sustained levels of the secreted morphogen Unpaired (Upd) specify the migratory border-cell population by activating the signal transducer and activator of transcription (STAT). A lower or transient level of STAT activity specifies a non-migratory population of follicle cells. Here we identify miR-279 as a component of a feedback pathway that further dampens the response in cells with low levels of JAK/STAT activity. miR-279 directly repressed STAT, and loss of miR-279 mimicked STAT gain-of-function or loss of Apontic (Apt), a known feedback inhibitor of STAT. Apt was essential for miR-279 expression in non-migratory follicle cells, whereas another STAT target, Ken and Barbie (Ken), downregulated miR-279 in border cells. Mathematical modelling and simulations of this regulatory circuit including miR-279, Apt and Ken supported key roles for miR-279 and Apt in generating threshold responses to the Upd gradient. PMID:21857668

  17. Sequence of neuron origin and neocortical laminar fate: relation to cell cycle of origin in the developing murine cerebral wall

    NASA Technical Reports Server (NTRS)

    Takahashi, T.; Goto, T.; Miyama, S.; Nowakowski, R. S.; Caviness, V. S. Jr

    1999-01-01

    Neurons destined for each region of the neocortex are known to arise approximately in an "inside-to-outside" sequence from a pseudostratified ventricular epithelium (PVE). This sequence is initiated rostrolaterally and propagates caudomedially. Moreover, independently of location in the PVE, the neuronogenetic sequence in mouse is divisible into 11 cell cycles that occur over a 6 d period. Here we use a novel "birth hour" method that identifies small cohorts of neurons born during a single 2 hr period, i.e., 10-20% of a single cell cycle, which corresponds to approximately 1.5% of the 6 d neuronogenetic period. This method shows that neurons arising with the same cycle of the 11 cycle sequence in mouse have common laminar fates even if they arise from widely separated positions on the PVE (neurons of fields 1 and 40) and therefore arise at different embryonic times. Even at this high level of temporal resolution, simultaneously arising cells occupy more than one cortical layer, and there is substantial overlap in the distributions of cells arising with successive cycles. We demonstrate additionally that the laminar representation of cells arising with a given cycle is little if at all modified over the early postnatal interval of histogenetic cell death. We infer from these findings that cell cycle is a neuronogenetic counting mechanism and that this counting mechanism is integral to subsequent processes that determine cortical laminar fate.

  18. Dermatan Sulfate Interacts with Dead Cells and Regulates CD5+ B-Cell Fate

    PubMed Central

    Wang, Julia Y.; Lee, Jongmin; Yan, Ming; Rho, Jung-hyun; Roehrl, Michael H.A.

    2011-01-01

    CD5+ (B-1a) B cells play pivotal roles in autoimmunity through expression of autoreactive B-cell receptors and production of autoantibodies. The mechanism underlying their positive selection and expansion is currently unknown. This study demonstrates that dermatan sulfate (DS) expands the B-1a cell population and augments the specific antibody response to an antigen when it is in complex with DS. DS displays preferential affinity for apoptotic and dead cells, and DS-stimulated cell cultures produce antibodies to various known autoantigens. The companion article further illustrates that autoantigens can be identified by affinity to DS, suggesting that molecules with affinity to DS have a high propensity to become autoantigens. We thus propose that the association of antigens from dead cells with DS is a possible origin of autoantigens and that autoreactive B-1a cells are positively selected and expanded by DS∙autoantigen complexes. This mechanism may also explain the clonal expansion of B-1a cells in certain B-cell malignancies. PMID:21514431

  19. Influences of LIN-12/Notch and POP-1/TCF on the Robustness of Ventral Uterine Cell Fate Specification in Caenorhabditis elegans Gonadogenesis.

    PubMed

    Sallee, Maria D; Aydin, Taner; Greenwald, Iva

    2015-10-19

    The prospective ventral uterus of the hermaphrodite gonad primordium consists of two pairs of sister cells, with each pair consisting of a proximal "α" cell and a distal "β" cell. All four cells initially are competent to become the anchor cell (AC), a unique cell type that acts as the organizer of subsequent uterine and vulval development. However, the β cells soon lose this competence and always become ventral uterine precursor cells (VUs), whereas the α cells maintain their AC competence longer, until lin-12/Notch-mediated interactions between them specify one as the AC and the other as a VU. Here, we investigate this asymmetry in developmental potential and VU fate specification between the α and β sister cells. We find evidence that lin-12 activity contributes to the robustness of βVU fate at elevated temperature, that the Caenorhabditis elegans Notch paralog glp-1 is not functionally redundant with lin-12 in specifying βVU fate, and that the activity of POP-1, the sole C. elegans TCF ortholog, influences βVU fate. We propose a model for how Wnt and LIN-12/Notch signaling together lead to robust specification of the βVU fate.

  20. Transcriptome Analysis of Soybean Leaf Abscission Identifies Transcriptional Regulators of Organ Polarity and Cell Fate

    PubMed Central

    Kim, Joonyup; Yang, Jinyoung; Yang, Ronghui; Sicher, Richard C.; Chang, Caren; Tucker, Mark L.

    2016-01-01

    Abscission, organ separation, is a developmental process that is modulated by endogenous and environmental factors. To better understand the molecular events underlying the progression of abscission in soybean, an agriculturally important legume, we performed RNA sequencing (RNA-seq) of RNA isolated from the leaf abscission zones (LAZ) and petioles (Non-AZ, NAZ) after treating stem/petiole explants with ethylene for 0, 12, 24, 48, and 72 h. As expected, expression of several families of cell wall modifying enzymes and many pathogenesis-related (PR) genes specifically increased in the LAZ as abscission progressed. Here, we focus on the 5,206 soybean genes we identified as encoding transcription factors (TFs). Of the 5,206 TFs, 1,088 were differentially up- or down-regulated more than eight-fold in the LAZ over time, and, within this group, 188 of the TFs were differentially regulated more than eight-fold in the LAZ relative to the NAZ. These 188 abscission-specific TFs include several TFs containing domains for homeobox, MYB, Zinc finger, bHLH, AP2, NAC, WRKY, YABBY, and auxin-related motifs. To discover the connectivity among the TFs and highlight developmental processes that support organ separation, the 188 abscission-specific TFs were then clustered based on a >four-fold up- or down-regulation in two consecutive time points (i.e., 0 and 12 h, 12 and 24 h, 24 and 48 h, or 48 and 72 h). By requiring a sustained change in expression over two consecutive time intervals and not just one or several time intervals, we could better tie changes in TFs to a particular process or phase of abscission. The greatest number of TFs clustered into the 0 and 12 h group. Transcriptional network analysis for these abscission-specific TFs indicated that most of these TFs are known as key determinants in the maintenance of organ polarity, lateral organ growth, and cell fate. The abscission-specific expression of these TFs prior to the onset of abscission and their functional

  1. THE FATE OF VACCINIA VIRUS ON CULTIVATION IN VITRO WITH KUPFFER CELLS (RETICULO-ENDOTHELIAL CELLS)

    PubMed Central

    Beard, Joseph W.; Rous, Peyton

    1938-01-01

    The pathogenic activity of vaccinia virus is in large part suppressed when it is mixed with living Kupffer cells or clasmatocytes in the test-tube and injected intradermally. Vaccinia increases in quantity when introduced into cultures of Kupffer cells in vitro, and survives in immediate association with these elements. No antiviral principle is elaborated by them under such conditions. PMID:19870763

  2. Structural and biochemical characterization of the cell fate determining nucleotidyltransferase fold protein MAB21L1

    PubMed Central

    de Oliveira Mann, Carina C.; Kiefersauer, Reiner; Witte, Gregor; Hopfner, Karl-Peter

    2016-01-01

    The exceptionally conserved metazoan MAB21 proteins are implicated in cell fate decisions and share considerable sequence homology with the cyclic GMP-AMP synthase. cGAS is the major innate immune sensor for cytosolic DNA and produces the second messenger 2′-5′, 3′-5′ cyclic GMP-AMP. Little is known about the structure and biochemical function of other proteins of the cGAS-MAB21 subfamily, such as MAB21L1, MAB21L2 and MAB21L3. We have determined the crystal structure of human full-length MAB21L1. Our analysis reveals high structural conservation between MAB21L1 and cGAS but also uncovers important differences. Although monomeric in solution, MAB21L1 forms a highly symmetric double-pentameric oligomer in the crystal, raising the possibility that oligomerization could be a feature of MAB21L1. In the crystal, MAB21L1 is in an inactive conformation requiring a conformational change - similar to cGAS - to develop any nucleotidyltransferase activity. Co-crystallization with NTP identified a putative ligand binding site of MAB21 proteins that corresponds to the DNA binding site of cGAS. Finally, we offer a structure-based explanation for the effects of MAB21L2 mutations in patients with eye malformations. The underlying residues participate in fold-stabilizing interaction networks and mutations destabilize the protein. In summary, we provide a first structural framework for MAB21 proteins. PMID:27271801

  3. Epigenetic profiles signify cell fate plasticity in unipotent spermatogonial stem and progenitor cells

    PubMed Central

    Liu, Ying; Giannopoulou, Eugenia G.; Wen, Duancheng; Falciatori, Ilaria; Elemento, Olivier; Allis, C. David; Rafii, Shahin; Seandel, Marco

    2016-01-01

    Spermatogonial stem and progenitor cells (SSCs) generate adult male gametes. During in vitro expansion, these unipotent murine cells spontaneously convert to multipotent adult spermatogonial-derived stem cells (MASCs). Here we investigate this conversion process through integrative transcriptomic and epigenomic analyses. We find in SSCs that promoters essential to maintenance and differentiation of embryonic stem cells (ESCs) are enriched with histone H3-lysine4 and -lysine 27 trimethylations. These bivalent modifications are maintained at most somatic promoters after conversion, bestowing MASCs an ESC-like promoter chromatin. At enhancers, the core pluripotency circuitry is activated partially in SSCs and completely in MASCs, concomitant with loss of germ cell-specific gene expression and initiation of embryonic-like programs. Furthermore, SSCs in vitro maintain the epigenomic characteristics of germ cells in vivo. Our observations suggest that SSCs encode innate plasticity through the epigenome and that both conversion of promoter chromatin states and activation of cell type-specific enhancers are prominent features of reprogramming. PMID:27117588

  4. Cytoplasmic NOTCH and membrane-derived β-catenin link cell fate choice to epithelial-mesenchymal transition during myogenesis

    PubMed Central

    Sieiro, Daniel; Rios, Anne C; Hirst, Claire E; Marcelle, Christophe

    2016-01-01

    How cells in the embryo coordinate epithelial plasticity with cell fate decision in a fast changing cellular environment is largely unknown. In chick embryos, skeletal muscle formation is initiated by migrating Delta1-expressing neural crest cells that trigger NOTCH signaling and myogenesis in selected epithelial somite progenitor cells, which rapidly translocate into the nascent muscle to differentiate. Here, we uncovered at the heart of this response a signaling module encompassing NOTCH, GSK-3β, SNAI1 and β-catenin. Independent of its transcriptional function, NOTCH profoundly inhibits GSK-3β activity. As a result SNAI1 is stabilized, triggering an epithelial to mesenchymal transition. This allows the recruitment of β-catenin from the membrane, which acts as a transcriptional co-factor to activate myogenesis, independently of WNT ligand. Our results intimately associate the initiation of myogenesis to a change in cell adhesion and may reveal a general principle for coupling cell fate changes to EMT in many developmental and pathological processes. DOI: http://dx.doi.org/10.7554/eLife.14847.001 PMID:27218451

  5. Mammary gland development: cell fate specification, stem cells and the microenvironment.

    PubMed

    Inman, Jamie L; Robertson, Claire; Mott, Joni D; Bissell, Mina J

    2015-03-15

    The development of the mammary gland is unique: the final stages of development occur postnatally at puberty under the influence of hormonal cues. Furthermore, during the life of the female, the mammary gland can undergo many rounds of expansion and proliferation. The mammary gland thus provides an excellent model for studying the 'stem/progenitor' cells that allow this repeated expansion and renewal. In this Review, we provide an overview of the different cell types that constitute the mammary gland, and discuss how these cell types arise and differentiate. As cellular differentiation cannot occur without proper signals, we also describe how the tissue microenvironment influences mammary gland development.

  6. The opposing roles of the transcription factor E2A and its antagonist Id3 that orchestrate and enforce the naive fate of T cells.

    PubMed

    Miyazaki, Masaki; Rivera, Richard R; Miyazaki, Kazuko; Lin, Yin C; Agata, Yasutoshi; Murre, Cornelis

    2011-08-21

    It is established that the transcription factor E2A and its antagonist Id3 modulate the checkpoints consisting of the precursor to the T cell antigen receptor (pre-TCR) and the TCR. Here we demonstrate that Id3 expression was higher beyond the pre-TCR checkpoint, remained high in naive T cells and showed a bimodal pattern in the effector-memory population. We show how E2A promoted T lineage specification and how pre-TCR-mediated signaling affected E2A genome-wide occupancy. Thymi in Id3-deficient mice had aberrant development of effector-memory cells, higher expression of the chemokine receptor CXCR5 and the transcriptional repressor Bcl-6 and, unexpectedly, T cell-B cell conjugates and B cell follicles. Collectively, our data show how E2A acted globally to orchestrate development into the T lineage and that Id3 antagonized E2A activity beyond the pre-TCR checkpoint to enforce the naive fate of T cells.

  7. Dynamical modeling of the cell cycle and cell fate emergence in Caulobacter crescentus.

    PubMed

    Quiñones-Valles, César; Sánchez-Osorio, Ismael; Martínez-Antonio, Agustino

    2014-01-01

    The division of Caulobacter crescentus, a model organism for studying cell cycle and differentiation in bacteria, generates two cell types: swarmer and stalked. To complete its cycle, C. crescentus must first differentiate from the swarmer to the stalked phenotype. An important regulator involved in this process is CtrA, which operates in a gene regulatory network and coordinates many of the interactions associated to the generation of cellular asymmetry. Gaining insight into how such a differentiation phenomenon arises and how network components interact to bring about cellular behavior and function demands mathematical models and simulations. In this work, we present a dynamical model based on a generalization of the Boolean abstraction of gene expression for a minimal network controlling the cell cycle and asymmetric cell division in C. crescentus. This network was constructed from data obtained from an exhaustive search in the literature. The results of the simulations based on our model show a cyclic attractor whose configurations can be made to correspond with the current knowledge of the activity of the regulators participating in the gene network during the cell cycle. Additionally, we found two point attractors that can be interpreted in terms of the network configurations directing the two cell types. The entire network is shown to be operating close to the critical regime, which means that it is robust enough to perturbations on dynamics of the network, but adaptable to environmental changes.

  8. Dynamical Modeling of the Cell Cycle and Cell Fate Emergence in Caulobacter crescentus

    PubMed Central

    Quiñones-Valles, César; Sánchez-Osorio, Ismael; Martínez-Antonio, Agustino

    2014-01-01

    The division of Caulobacter crescentus, a model organism for studying cell cycle and differentiation in bacteria, generates two cell types: swarmer and stalked. To complete its cycle, C. crescentus must first differentiate from the swarmer to the stalked phenotype. An important regulator involved in this process is CtrA, which operates in a gene regulatory network and coordinates many of the interactions associated to the generation of cellular asymmetry. Gaining insight into how such a differentiation phenomenon arises and how network components interact to bring about cellular behavior and function demands mathematical models and simulations. In this work, we present a dynamical model based on a generalization of the Boolean abstraction of gene expression for a minimal network controlling the cell cycle and asymmetric cell division in C. crescentus. This network was constructed from data obtained from an exhaustive search in the literature. The results of the simulations based on our model show a cyclic attractor whose configurations can be made to correspond with the current knowledge of the activity of the regulators participating in the gene network during the cell cycle. Additionally, we found two point attractors that can be interpreted in terms of the network configurations directing the two cell types. The entire network is shown to be operating close to the critical regime, which means that it is robust enough to perturbations on dynamics of the network, but adaptable to environmental changes. PMID:25369202

  9. Forcing neural progenitor cells to cycle is insufficient to alter cell-fate decision and timing of neuronal differentiation in the spinal cord

    PubMed Central

    Lobjois, Valérie; Bel-Vialar, Sophie; Trousse, Françoise; Pituello, Fabienne

    2008-01-01

    Background During the development of the nervous system, neural progenitor cells can either stay in the pool of proliferating undifferentiated cells or exit the cell cycle and differentiate. Two main factors will determine the fate of a neural progenitor cell: its position within the neuroepithelium and the time at which the cell initiates differentiation. In this paper we investigated the importance of the timing of cell cycle exit on cell-fate decision by forcing neural progenitors to cycle and studying the consequences on specification and differentiation programs. Results As a model, we chose the spinal progenitors of motor neurons (pMNs), which switch cell-fate from motor neurons to oligodendrocytes with time. To keep pMNs in the cell cycle, we forced the expression of G1-phase regulators, the D-type cyclins. We observed that keeping neural progenitor cells cycling is not sufficient to retain them in the progenitor domain (ventricular zone); transgenic cells instead migrate to the differentiating field (mantle zone) regardless of cell cycle exit. Cycling cells located in the mantle zone do not retain markers of neural progenitor cells such as Sox2 or Olig2 but upregulate transcription factors involved in motor neuron specification, including MNR2 and Islet1/2. These cycling cells also progress through neuronal differentiation to axonal extension. We also observed mitotic cells displaying all the features of differentiating motor neurons, including axonal projection via the ventral root. However, the rapid decrease observed in the proliferation rate of the transgenic motor neuron population suggests that they undergo only a limited number of divisions. Finally, quantification of the incidence of the phenotype in young and more mature neuroepithelium has allowed us to propose that once the transcriptional program assigning neural progenitor cells to a subtype of neurons is set up, transgenic cells progress in their program of differentiation regardless of cell

  10. E. coli fate and transport in the Happel sphere-in-cell model

    NASA Astrophysics Data System (ADS)

    Nelson, K. E.; Massoudieh, A.; Ginn, T. R.

    2007-06-01

    Rates of mass and gene transfer reactions involving biotic phases are often expressed as proportional to local number densities of bacteria. When the reactions involve attached bacteria, reaction rates depend on local densities of bacteria attached to surfaces. Such may be the case with microbially-facilitated redox reactions involving mineral electron donors and mineral electron receivers (e.g., Sani RK, Peyton BM, Amonette JE, Dohnalkova A. Reoxidation of uranium in the presence of iron(III)-(hydr)oxides under sulfate reducing conditions. Environ Sci Technol 2005;39:2059-66), biofilm formation induced by quorum sensing (Purevdorj B, Costerton JW, Stoodley P. Influence of hydrodynamics and cell signaling on the structure and behavior of Pseudomonas aeruginosa Biofilms. Appl Environ Microbiol 2002;68(9):4457-64) and horizontal gene transfer among attached phase bacteria (Beaudoin DL, Bryers JD, Cunningham AB, Peretti SW. Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. I. Experiments. Biotech Bioeng 1998a;57(3):272-79; Beaudoin DL, Bryers JD, Cunningham AB, Peretti SW. Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. II. Modeling Biotech Bioeng 1998b;57(3):280-86). Here we use the conceptual Happel sphere-in-cell model to determine the microscopic distribution of attached bacteria on idealized spherical grains of porous media, assuming azimuthal symmetry. We extend a Lagrangian model of colloid filtration to investigate the effects of motility of Escherichia coli on attachment rate and on the attachment distribution as a function of location on grain surface. The hydrodynamics of the Happel model is implicitly 3D and represented in 2D polar coordinates under the assumption of axisymmetric flow, while the motility of the E. coli cells is explicitly 3D. The model incorporates the fate and transport processes of colloid filtration theory in

  11. Genetic background affects susceptibility to tumoral stem cell reprogramming

    PubMed Central

    García-Ramírez, Idoia; Ruiz-Roca, Lucía; Martín-Lorenzo, Alberto; Blanco, Óscar; García-Cenador, María Begoña; García-Criado, Francisco Javier; Vicente-Dueñas, Carolina; Sánchez-García, Isidro

    2013-01-01

    The latest studies of the interactions between oncogenes and its target cell have shown that certain oncogenes may act as passengers to reprogram tissue-specific stem/progenitor cell into a malignant cancer stem cell state. In this study, we show that the genetic background influences this tumoral stem cell reprogramming capacity of the oncogenes using as a model the Sca1-BCRABLp210 mice, where the type of tumor they develop, chronic myeloid leukemia (CML), is a function of tumoral stem cell reprogramming. Sca1-BCRABLp210 mice containing FVB genetic components were significantly more resistant to CML. However, pure Sca1-BCRABLp210 FVB mice developed thymomas that were not seen in the Sca1-BCRABLp210 mice into the B6 background. Collectively, our results demonstrate for the first time that tumoral stem cell reprogramming fate is subject to polymorphic genetic control. PMID:23839033

  12. A cell cycle kinase with tandem sensory PAS domains integrates cell fate cues

    PubMed Central

    Mann, Thomas H.; Seth Childers, W.; Blair, Jimmy A.; Eckart, Michael R.; Shapiro, Lucy

    2016-01-01

    All cells must integrate sensory information to coordinate developmental events in space and time. The bacterium Caulobacter crescentus uses two-component phospho-signalling to regulate spatially distinct cell cycle events through the master regulator CtrA. Here, we report that CckA, the histidine kinase upstream of CtrA, employs a tandem-PAS domain sensor to integrate two distinct spatiotemporal signals. Using CckA reconstituted on liposomes, we show that one PAS domain modulates kinase activity in a CckA density-dependent manner, mimicking the stimulation of CckA kinase activity that occurs on its transition from diffuse to densely packed at the cell poles. The second PAS domain interacts with the asymmetrically partitioned second messenger cyclic-di-GMP, inhibiting kinase activity while stimulating phosphatase activity, consistent with the selective inactivation of CtrA in the incipient stalked cell compartment. The integration of these spatially and temporally regulated signalling events within a single signalling receptor enables robust orchestration of cell-type-specific gene regulation. PMID:27117914

  13. Tetraploidization or autophagy: The ultimate fate of senescent human endometrial stem cells under ATM or p53 inhibition.

    PubMed

    Borodkina, Aleksandra V; Shatrova, Alla N; Deryabin, Pavel I; Grukova, Anastasiya A; Nikolsky, Nikolay N; Burova, Elena B

    2016-01-01

    Previously we demonstrated that endometrium-derived human mesenchymal stem cells (hMESCs) via activation of the ATM/p53/p21/Rb pathway enter the premature senescence in response to oxidative stress. Down regulation effects of the key components of this signaling pathway, particularly ATM and p53, on a fate of stressed hMESCs have not yet been investigated. In the present study by using the specific inhibitors Ku55933 and Pifithrin-α, we confirmed implication of both ATM and p53 in H(2)O(2)-induced senescence of hMESCs. ATM or p53 down regulation was shown to modulate differently the cellular fate of H(2)O(2)-treated hMESCs. ATM inhibition allowed H(2)O(2)-stimulated hMESCs to escape the permanent cell cycle arrest due to loss of the functional ATM/p53/p21/Rb pathway, and induced bypass of mitosis and re-entry into S phase, resulting in tetraploid cells. On the contrary, suppression of the p53 transcriptional activity caused a pronounced cell death of H(2)O(2)-treated hMESCs via autophagy induction. The obtained data clearly demonstrate that down regulation of ATM or p53 shifts senescence of human endometrial stem cells toward tetraploidization or autophagy.

  14. Proteomic Analysis of Sox2-associated Proteins During Early Stages of Mouse Embryonic Stem Cell Differentiation Identifies Sox21 as a Novel Regulator of Stem Cell Fate

    PubMed Central

    Mallanna, Sunil K.; Ormsbee, Briana D.; Iacovino, Michelina; Gilmore, Joshua M.; Cox, Jesse L.; Kyba, Michael; Washburn, Michael P.; Rizzino, Angie

    2012-01-01

    Small increases in the levels of master regulators, such as Sox2, in embryonic stem cells (ESC) have been shown to promote their differentiation. However, the mechanism by which Sox2 controls the fate of ESC is poorly understood. In this study, we employed Multidimensional Protein Identification Technology and identified >60 nuclear proteins that associate with Sox2 early during ESC differentiation. Gene ontology analysis of Sox2-associated proteins indicates that they participate in a wide range of processes. Equally important, a significant number of the Sox2-associated proteins identified in this study have been shown previously to interact with Oct4, Nanog, Sall4 and Essrb. Moreover, we examined the impact of manipulating the expression of a Sox2-associated protein on the fate of ESC. Using ESC engineered for inducible expression of Sox21, we show that ectopic expression of Sox21 in ESC induces their differentiation into specific cell types, including those that express markers representative of neurectoderm and heart development. Collectively, these studies provide new insights into the range of molecular processes through which Sox2 is likely to influence the fate of ESC, and provide further support for the conclusion that the expression of Sox proteins in ESC must be precisely regulated. Importantly, our studies also argue that Sox2, along with other pluripotency-associated transcription factors, is woven into highly interconnected regulatory networks that function at several levels to control the fate of ESC. PMID:20687156

  15. Fate Mapping for Activation-Induced Cytidine Deaminase (AID) Marks Non-Lymphoid Cells During Mouse Development

    PubMed Central

    Rommel, Philipp C.; Bosque, David; Gitlin, Alexander D.; Croft, Gist F.; Heintz, Nathaniel; Casellas, Rafael; Nussenzweig, Michel C.; Kriaucionis, Skirmantas; Robbiani, Davide F.

    2013-01-01

    The Aicda gene encodes Activation-Induced cytidine Deaminase (AID), an enzyme essential for remodeling antibody genes in mature B lymphocytes. AID is also responsible for DNA damage at oncogenes, leading to their mutation and cancer-associated chromosome translocation in lymphoma. We used fate mapping and AIDGFP reporter mice to determine if AID expression in the mouse extends beyond lymphocytes. We discovered that AIDcre tags a small fraction of non-lymphoid cells starting at 10.5 days post conception (dpc), and that AIDGFP+ cells are detectable at dpc 11.5 and 12.5. Embryonic cells are tagged by AIDcre in the submandibular region, where conditional deletion of the tumor suppressor PTEN causes squamous papillomas. AIDcre also tags non-lymphoid cells in the embryonic central nervous system. Finally, in the adult mouse brain, AIDcre marks a small fraction of diverse neurons and distinct neuronal populations, including pyramidal cells in cortical layer IV. PMID:23861962

  16. Mammary Stem Cell Based Somatic Mouse Models Reveal Breast Cancer Drivers Causing Cell Fate Dysregulation

    PubMed Central

    Zhang, Zheng; Christin, John R.; Wang, Chunhui; Ge, Kai; Oktay, Maja H.; Guo, Wenjun

    2016-01-01

    SUMMARY Cancer genomics have provided an unprecedented opportunity for understanding genetic causes of human cancer. However, distinguishing which mutations are functionally relevant to cancer pathogenesis remains a major challenge. We describe here a mammary stem cell (MaSC) organoid-based approach for rapid generation of somatic GEMMs (genetically engineered mouse models). By using RNAi and CRISPR-mediated genome engineering in MaSC-GEMMs, we have discovered that inactivation of Ptpn22 or Mll3, two genes mutated in human breast cancer, greatly accelerated PI3K-driven mammary tumorigenesis. Using these tumor models, we have also identified genetic alterations promoting tumor metastasis and causing resistance to PI3K-targeted therapy. Both Ptpn22 and Mll3 inactivation resulted in disruption of mammary gland differentiation and an increase in stem cell activity. Mechanistically, Mll3 deletion enhanced stem cell activity through activation of the HIF pathway. Thus, our study established a robust in vivo platform for functional cancer genomics and discovered functional breast cancer mutations. PMID:27653681

  17. Mammary-Stem-Cell-Based Somatic Mouse Models Reveal Breast Cancer Drivers Causing Cell Fate Dysregulation.

    PubMed

    Zhang, Zheng; Christin, John R; Wang, Chunhui; Ge, Kai; Oktay, Maja H; Guo, Wenjun

    2016-09-20

    Cancer genomics has provided an unprecedented opportunity for understanding genetic causes of human cancer. However, distinguishing which mutations are functionally relevant to cancer pathogenesis remains a major challenge. We describe here a mammary stem cell (MaSC) organoid-based approach for rapid generation of somatic genetically engineered mouse models (GEMMs). By using RNAi and CRISPR-mediated genome engineering in MaSC-GEMMs, we have discovered that inactivation of Ptpn22 or Mll3, two genes mutated in human breast cancer, greatly accelerated PI3K-driven mammary tumorigenesis. Using these tumor models, we have also identified genetic alterations promoting tumor metastasis and causing resistance to PI3K-targeted therapy. Both Ptpn22 and Mll3 inactivation resulted in disruption of mammary gland differentiation and an increase in stem cell activity. Mechanistically, Mll3 deletion enhanced stem cell activity through activation of the HIF pathway. Thus, our study has established a robust in vivo platform for functional cancer genomics and has discovered functional breast cancer mutations. PMID:27653681

  18. TGFβ and BMP Dependent Cell Fate Changes Due to Loss of Filamin B Produces Disc Degeneration and Progressive Vertebral Fusions

    PubMed Central

    Zieba, Jennifer; Forlenza, Kimberly Nicole; Khatra, Jagteshwar Singh; Sarukhanov, Anna; Duran, Ivan; Rigueur, Diana; Lyons, Karen M.; Cohn, Daniel H.; Merrill, Amy E.; Krakow, Deborah

    2016-01-01

    Spondylocarpotarsal synostosis (SCT) is an autosomal recessive disorder characterized by progressive vertebral fusions and caused by loss of function mutations in Filamin B (FLNB). FLNB acts as a signaling scaffold by linking the actin cytoskleteon to signal transduction systems, yet the disease mechanisms for SCT remain unclear. Employing a Flnb knockout mouse, we found morphologic and molecular evidence that the intervertebral discs (IVDs) of Flnb–/–mice undergo rapid and progressive degeneration during postnatal development as a result of abnormal cell fate changes in the IVD, particularly the annulus fibrosus (AF). In Flnb–/–mice, the AF cells lose their typical fibroblast-like characteristics and acquire the molecular and phenotypic signature of hypertrophic chondrocytes. This change is characterized by hallmarks of endochondral-like ossification including alterations in collagen matrix, expression of Collagen X, increased apoptosis, and inappropriate ossification of the disc tissue. We show that conversion of the AF cells into chondrocytes is coincident with upregulated TGFβ signaling via Smad2/3 and BMP induced p38 signaling as well as sustained activation of canonical and noncanonical target genes p21 and Ctgf. These findings indicate that FLNB is involved in attenuation of TGFβ/BMP signaling and influences AF cell fate. Furthermore, we demonstrate that the IVD disruptions in Flnb–/–mice resemble aging degenerative discs and reveal new insights into the molecular causes of vertebral fusions and disc degeneration. PMID:27019229

  19. TGFβ and BMP Dependent Cell Fate Changes Due to Loss of Filamin B Produces Disc Degeneration and Progressive Vertebral Fusions.

    PubMed

    Zieba, Jennifer; Forlenza, Kimberly Nicole; Khatra, Jagteshwar Singh; Sarukhanov, Anna; Duran, Ivan; Rigueur, Diana; Lyons, Karen M; Cohn, Daniel H; Merrill, Amy E; Krakow, Deborah

    2016-03-01

    Spondylocarpotarsal synostosis (SCT) is an autosomal recessive disorder characterized by progressive vertebral fusions and caused by loss of function mutations in Filamin B (FLNB). FLNB acts as a signaling scaffold by linking the actin cytoskleteon to signal transduction systems, yet the disease mechanisms for SCT remain unclear. Employing a Flnb knockout mouse, we found morphologic and molecular evidence that the intervertebral discs (IVDs) of Flnb-/-mice undergo rapid and progressive degeneration during postnatal development as a result of abnormal cell fate changes in the IVD, particularly the annulus fibrosus (AF). In Flnb-/-mice, the AF cells lose their typical fibroblast-like characteristics and acquire the molecular and phenotypic signature of hypertrophic chondrocytes. This change is characterized by hallmarks of endochondral-like ossification including alterations in collagen matrix, expression of Collagen X, increased apoptosis, and inappropriate ossification of the disc tissue. We show that conversion of the AF cells into chondrocytes is coincident with upregulated TGFβ signaling via Smad2/3 and BMP induced p38 signaling as well as sustained activation of canonical and noncanonical target genes p21 and Ctgf. These findings indicate that FLNB is involved in attenuation of TGFβ/BMP signaling and influences AF cell fate. Furthermore, we demonstrate that the IVD disruptions in Flnb-/-mice resemble aging degenerative discs and reveal new insights into the molecular causes of vertebral fusions and disc degeneration. PMID:27019229

  20. Epigenetic Induction of Definitive and Pancreatic Endoderm Cell Fate in Human Fibroblasts

    PubMed Central

    Faas, Marijke M.; de Vos, Paul; Verfaillie, Catherine M.

    2016-01-01

    Reprogramming can occur by the introduction of key transcription factors (TFs) as well as by epigenetic changes. We demonstrated that histone deacetylase inhibitor (HDACi) Trichostatin A (TSA) combined with a chromatin remodeling medium (CRM) induced expression of a number of definitive endoderm and early and late pancreatic marker genes. When CRM was omitted, endoderm/pancreatic marker genes were not induced. Furthermore, treatment with DNA methyltransferase inhibitor (DNMTi) 5-azacytidine (5AZA) CRM did not affect gene expression changes, and when 5AZA was combined with TSA, no further increase in gene expression of endoderm, pancreatic endoderm, and endocrine markers was seen over levels induced with TSA alone. Interestingly, TSA-CRM did not affect expression of pluripotency and hepatocyte genes but induced some mesoderm transcripts. Upon removal of TSA-CRM, the endoderm/pancreatic gene expression profile returned to baseline. Our findings underscore the role epigenetic modification in transdifferentiation of one somatic cell into another. However, full reprogramming of fibroblasts to β-cells will require combination of this approach with TF overexpression and/or culture of the partially reprogrammed cells under β-cell specific conditions. PMID:27403168

  1. hESC Differentiation toward an Autonomic Neuronal Cell Fate Depends on Distinct Cues from the Co-Patterning Vasculature

    PubMed Central

    Acevedo, Lisette M.; Lindquist, Jeffrey N.; Walsh, Breda M.; Sia, Peik; Cimadamore, Flavio; Chen, Connie; Denzel, Martin; Pernia, Cameron D.; Ranscht, Barbara; Terskikh, Alexey; Snyder, Evan Y.; Cheresh, David A.

    2015-01-01

    Summary To gain insight into the cellular and molecular cues that promote neurovascular co-patterning at the earliest stages of human embryogenesis, we developed a human embryonic stem cell model to mimic the developing epiblast. Contact of ectoderm-derived neural cells with mesoderm-derived vasculature is initiated via the neural crest (NC), not the neural tube (NT). Neurovascular co-patterning then ensues with specification of NC toward an autonomic fate requiring vascular endothelial cell (EC)-secreted nitric oxide (NO) and direct contact with vascular smooth muscle cells (VSMCs) via T-cadherin-mediated homotypic interactions. Once a neurovascular template has been established, NT-derived central neurons then align themselves with the vasculature. Our findings reveal that, in early human development, the autonomic nervous system forms in response to distinct molecular cues from VSMCs and ECs, providing a model for how other developing lineages might coordinate their co-patterning. PMID:26004631

  2. Getting the right stuff: controlling neural stem cell state and fate in vivo and in vitro with biomaterials.

    PubMed

    Teixeira, Ana I; Duckworth, Joshua K; Hermanson, Ola

    2007-01-01

    Stem cell therapy holds great promises in medical treatment by, e.g., replacing lost cells, re-constitute healthy cell populations and also in the use of stem cells as vehicles for factor and gene delivery. Embryonic stem cells have rightfully attracted a large interest due to their proven capacity of differentiating into any cell type in the embryo in vivo. Tissue-specific stem cells are however already in use in medical practice, and recently the first systematic medical trials involving human neural stem cell (NSC) therapy have been launched. There are yet many obstacles to overcome and procedures to improve. To ensure progress in the medical use of stem cells increased basic knowledge of the molecular mechanisms that govern stem cell characteristics is necessary. Here we provide a review of the literature on NSCs in various aspects of cell therapy, with the main focus on the potential of using biomaterials to control NSC characteristics, differentiation, and delivery. We summarize results from studies on the characteristics of endogenous and transplanted NSCs in rodent models of neurological and cancer diseases, and highlight recent advancements in polymer compatibility and applicability in regulating NSC state and fate. We suggest that the development of specially designed polymers, such as hydrogels, is a crucial issue to improve the outcome of stem cell therapy in the central nervous system. PMID:17211445

  3. Pak2 Controls Acquisition of NKT Cell Fate by Regulating Expression of the Transcription Factors PLZF and Egr2.

    PubMed

    O'Hagan, Kyle L; Zhao, Jie; Pryshchep, Olga; Wang, Chyung-Ru; Phee, Hyewon

    2015-12-01

    NKT cells constitute a small population of T cells developed in the thymus that produce large amounts of cytokines and chemokines in response to lipid Ags. Signaling through the Vα14-Jα18 TCR instructs commitment to the NKT cell lineage, but the precise signaling mechanisms that instruct their lineage choice are unclear. In this article, we report that the cytoskeletal remodeling protein, p21-activated kinase 2 (Pak2), was essential for NKT cell development. Loss of Pak2 in T cells reduced stage III NKT cells in the thymus and periphery. Among different NKT cell subsets, Pak2 was necessary for the generation and function of NKT1 and NKT2 cells, but not NKT17 cells. Mechanistically, expression of Egr2 and promyelocytic leukemia zinc finger (PLZF), two key transcription factors for acquiring the NKT cell fate, were markedly diminished in the absence of Pak2. Diminished expression of Egr2 and PLZF were not caused by aberrant TCR signaling, as determined using a Nur77-GFP reporter, but were likely due to impaired induction and maintenance of signaling lymphocyte activation molecule 6 expression, a TCR costimulatory receptor required for NKT cell development. These data suggest that Pak2 controls thymic NKT cell development by providing a signal that links Egr2 to induce PLZF, in part by regulating signaling lymphocyte activation molecule 6 expression. PMID:26519537

  4. Getting the right stuff: controlling neural stem cell state and fate in vivo and in vitro with biomaterials.

    PubMed

    Teixeira, Ana I; Duckworth, Joshua K; Hermanson, Ola

    2007-01-01

    Stem cell therapy holds great promises in medical treatment by, e.g., replacing lost cells, re-constitute healthy cell populations and also in the use of stem cells as vehicles for factor and gene delivery. Embryonic stem cells have rightfully attracted a large interest due to their proven capacity of differentiating into any cell type in the embryo in vivo. Tissue-specific stem cells are however already in use in medical practice, and recently the first systematic medical trials involving human neural stem cell (NSC) therapy have been launched. There are yet many obstacles to overcome and procedures to improve. To ensure progress in the medical use of stem cells increased basic knowledge of the molecular mechanisms that govern stem cell characteristics is necessary. Here we provide a review of the literature on NSCs in various aspects of cell therapy, with the main focus on the potential of using biomaterials to control NSC characteristics, differentiation, and delivery. We summarize results from studies on the characteristics of endogenous and transplanted NSCs in rodent models of neurological and cancer diseases, and highlight recent advancements in polymer compatibility and applicability in regulating NSC state and fate. We suggest that the development of specially designed polymers, such as hydrogels, is a crucial issue to improve the outcome of stem cell therapy in the central nervous system.

  5. The Effect of Topography on Differentiation Fates of Matrigel-Coated Mouse Embryonic Stem Cells Cultured on PLGA Nanofibrous Scaffolds

    PubMed Central

    Abasi, Mozhgan; Babaloo, Hamideh; Terraf, Panieh; Safi, Mojtaba; Saeed, Mahdi; Barzin, Jalal; Zandi, Mojgan; Soleimani, Masoud

    2012-01-01

    Due to pluripotency of embryonic stem (ES) cells, these cells are an invaluable in vitro model that investigates the influence of different physical and chemical cues on differentiation/development pathway of specialized cells. We sought the effect of roughness and alignment, as topomorpholocial properties of scaffolds on differentiation of green fluorescent protein-expressing ES (GFP-ES) cells into three germ layers derivates simultaneously. Furthermore, the effect of Matrigel as a natural extracellular matrix in combination with poly(lactic-co-glycolic acid) (PLGA) nanofibrous scaffolds on differentiation of mouse ES cells has been investigated. The PLGA nanofibrous scaffolds with different height and distribution of roughness and alignments were fabricated. Then, the different cell differentiation fats of GFP-ES cells plated on PLGA and PLGA/Matrigel scaffolds were analyzed by gene expression profiling. The findings demonstrated that distinct ranges of roughness, height, and distribution can support/promote a specific cell differentiation fate on scaffolds. Coating of scaffolds with Matrigel has a synergistic effect in differentiation of mesoderm-derived cells and germ cells from ES cells, whereas it inhibits the derivation of endodermal cell lineages. It was concluded that the topomorpholocial cues such as roughness and alignment should be considered in addition to other scaffolds properties to design an efficient electrospun scaffold for specific tissue engineering. PMID:21981309

  6. m(6)A RNA modification controls cell fate transition in mammalian embryonic stem cells.

    PubMed

    Batista, Pedro J; Molinie, Benoit; Wang, Jinkai; Qu, Kun; Zhang, Jiajing; Li, Lingjie; Bouley, Donna M; Lujan, Ernesto; Haddad, Bahareh; Daneshvar, Kaveh; Carter, Ava C; Flynn, Ryan A; Zhou, Chan; Lim, Kok-Seong; Dedon, Peter; Wernig, Marius; Mullen, Alan C; Xing, Yi; Giallourakis, Cosmas C; Chang, Howard Y

    2014-12-01

    N6-methyl-adenosine (m(6)A) is the most abundant modification on messenger RNAs and is linked to human diseases, but its functions in mammalian development are poorly understood. Here we reveal the evolutionary conservation and function of m(6)A by mapping the m(6)A methylome in mouse and human embryonic stem cells. Thousands of messenger and long noncoding RNAs show conserved m(6)A modification, including transcripts encoding core pluripotency transcription factors. m(6)A is enriched over 3' untranslated regions at defined sequence motifs and marks unstable transcripts, including transcripts turned over upon differentiation. Genetic inactivation or depletion of mouse and human Mettl3, one of the m(6)A methylases, led to m(6)A erasure on select target genes, prolonged Nanog expression upon differentiation, and impaired ESC exit from self-renewal toward differentiation into several lineages in vitro and in vivo. Thus, m(6)A is a mark of transcriptome flexibility required for stem cells to differentiate to specific lineages.

  7. m6A RNA modification controls cell fate transition in mammalian embryonic stem cells

    PubMed Central

    Batista, Pedro J; Molinie, Benoit; Wang, Jinkai; Qu, Kun; Zhang, Jiajing; Li, Lingjie; Bouley, Donna M; Lujan, Ernesto; Haddad, Bahareh; Daneshvar, Kaveh; Carter, Ava C; Flynn, Ryan A; Zhou, Chan; Lim, Kok-Seong; Dedon, Peter; Wernig, Marius; Mullen, Alan C; Xing, Yi; Giallourakis, Cosmas C; Chang, Howard Y

    2014-01-01

    SUMMARY N6-methyl-adenosine (m6A) is the most abundant modification on messenger RNAs and is linked to human diseases, but its functions in mammalian development are poorly understood. Here we reveal the evolutionary conservation and function of m6A by mapping the m6A methylome in mouse and human embryonic stem cells. Thousands of messenger and long noncoding RNAs show conserved m6A modification, including transcripts encoding core pluripotency transcription factors. m6A is enriched over 3′ untranslated regions at defined sequence motifs, and marks unstable transcripts, including transcripts turned over upon differentiation. Genetic inactivation or depletion of mouse and human Mettl3, one of the m6A methylases, led to m6A erasure on select target genes, prolonged Nanog expression upon differentiation, and impaired ESC’s exit from self-renewal towards differentiation into several lineages in vitro and in vivo. Thus, m6A is a mark of transcriptome flexibility required for stem cells to differentiate to specific lineages. PMID:25456834

  8. Highly variable individual donor cell fates characterize robust horizontal gene transfer of an integrative and conjugative element

    PubMed Central

    Delavat, François; Mitri, Sara; Pelet, Serge; van der Meer, Jan Roelof

    2016-01-01

    Horizontal gene transfer is an important evolutionary mechanism for bacterial adaptation. However, given the typical low transfer frequencies in a bacterial population, little is known about the fate and interplay of donor cells and the mobilized DNA during transfer. Here we study transfer of an integrative and conjugative element (ICE) among individual live bacterial cells. ICEs are widely distributed mobile DNA elements that are different than plasmids because they reside silent in the host chromosome and are maintained through vertical descent. Occasionally, ICEs become active, excise, and transmit their DNA to a new recipient, where it is reintegrated. We develop a fluorescent tool to differentiate excision, transfer, and reintegration of a model ICE named ICEclc (for carrying the clc genes for chlorocatechol metabolism) among single Pseudomonas cells by using time-lapse microscopy. We find that ICEclc activation is initiated in stationary phase cells, but excision and transfer predominantly occur only when such cells have been presented with new nutrients. Donors with activated ICE develop a number of different states, characterized by reduced cell division rates or growth arrest, persistence, or lysis, concomitant with ICE excision, and likely, ICE loss or replication. The donor cell state transitions can be described by using a stochastic model, which predicts that ICE fitness is optimal at low initiation rates in stationary phase. Despite highly variable donor cell fates, ICE transfer is remarkably robust overall, with 75% success after excision. Our results help to better understand ICE behavior and shed a new light on bacterial cellular differentiation during horizontal gene transfer. PMID:27247406

  9. Highly variable individual donor cell fates characterize robust horizontal gene transfer of an integrative and conjugative element.

    PubMed

    Delavat, François; Mitri, Sara; Pelet, Serge; van der Meer, Jan Roelof

    2016-06-14

    Horizontal gene transfer is an important evolutionary mechanism for bacterial adaptation. However, given the typical low transfer frequencies in a bacterial population, little is known about the fate and interplay of donor cells and the mobilized DNA during transfer. Here we study transfer of an integrative and conjugative element (ICE) among individual live bacterial cells. ICEs are widely distributed mobile DNA elements that are different than plasmids because they reside silent in the host chromosome and are maintained through vertical descent. Occasionally, ICEs become active, excise, and transmit their DNA to a new recipient, where it is reintegrated. We develop a fluorescent tool to differentiate excision, transfer, and reintegration of a model ICE named ICEclc (for carrying the clc genes for chlorocatechol metabolism) among single Pseudomonas cells by using time-lapse microscopy. We find that ICEclc activation is initiated in stationary phase cells, but excision and transfer predominantly occur only when such cells have been presented with new nutrients. Donors with activated ICE develop a number of different states, characterized by reduced cell division rates or growth arrest, persistence, or lysis, concomitant with ICE excision, and likely, ICE loss or replication. The donor cell state transitions can be described by using a stochastic model, which predicts that ICE fitness is optimal at low initiation rates in stationary phase. Despite highly variable donor cell fates, ICE transfer is remarkably robust overall, with 75% success after ex