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Sample records for regulates stem cell

  1. Nuclear receptor regulation of stemness and stem cell differentiation

    PubMed Central

    Jeong, Yangsik

    2009-01-01

    Stem cells include a diverse number of toti-, pluri-, and multi-potent cells that play important roles in cellular genesis and differentiation, tissue development, and organogenesis. Genetic regulation involving various transcription factors results in the self-renewal and differentiation properties of stem cells. The nuclear receptor (NR) superfamily is composed of 48 ligand-activated transcription factors involved in diverse physiological functions such as metabolism, development, and reproduction. Increasing evidence shows that certain NRs function in regulating stemness or differentiation of embryonic stem (ES) cells and tissue-specific adult stem cells. Here, we review the role of the NR superfamily in various aspects of stem cell biology, including their regulation of stemness, forward- and trans-differentiation events; reprogramming of terminally differentiated cells; and interspecies differences. These studies provide insights into the therapeutic potential of the NR superfamily in stem cell therapy and in treating stem cell-associated diseases (e.g., cancer stem cell). PMID:19696553

  2. Materials as stem cell regulators

    NASA Astrophysics Data System (ADS)

    Murphy, William L.; McDevitt, Todd C.; Engler, Adam J.

    2014-06-01

    The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the material cooperatively dictate one another's fate: the cell by remodelling its surroundings, and the material through its inherent properties (such as adhesivity, stiffness, nanostructure or degradability). Stem cells in contact with materials are able to sense their properties, integrate cues via signal propagation and ultimately translate parallel signalling information into cell fate decisions. However, discovering the mechanisms by which stem cells respond to inherent material characteristics is challenging because of the highly complex, multicomponent signalling milieu present in the stem cell environment. In this Review, we discuss recent evidence that shows that inherent material properties may be engineered to dictate stem cell fate decisions, and overview a subset of the operative signal transduction mechanisms that have begun to emerge. Further developments in stem cell engineering and mechanotransduction are poised to have substantial implications for stem cell biology and regenerative medicine.

  3. Materials as stem cell regulators

    PubMed Central

    Murphy, William L.; McDevitt, Todd C.; Engler, Adam J.

    2014-01-01

    The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the material cooperatively dictate one another's fate: the cell by remodelling its surroundings, and the material through its inherent properties (such as adhesivity, stiffness, nanostructure or degradability). Stem cells in contact with materials are able to sense their properties, integrate cues via signal propagation and ultimately translate parallel signalling information into cell fate decisions. However, discovering the mechanisms by which stem cells respond to inherent material characteristics is challenging because of the highly complex, multicomponent signalling milieu present in the stem cell environment. In this Review, we discuss recent evidence that shows that inherent material properties may be engineered to dictate stem cell fate decisions, and overview a subset of the operative signal transduction mechanisms that have begun to emerge. Further developments in stem cell engineering and mechanotransduction are poised to have substantial implications for stem cell biology and regenerative medicine. PMID:24845994

  4. Cell cycle regulation in hematopoietic stem cells.

    PubMed

    Pietras, Eric M; Warr, Matthew R; Passegué, Emmanuelle

    2011-11-28

    Hematopoietic stem cells (HSCs) give rise to all lineages of blood cells. Because HSCs must persist for a lifetime, the balance between their proliferation and quiescence is carefully regulated to ensure blood homeostasis while limiting cellular damage. Cell cycle regulation therefore plays a critical role in controlling HSC function during both fetal life and in the adult. The cell cycle activity of HSCs is carefully modulated by a complex interplay between cell-intrinsic mechanisms and cell-extrinsic factors produced by the microenvironment. This fine-tuned regulatory network may become altered with age, leading to aberrant HSC cell cycle regulation, degraded HSC function, and hematological malignancy.

  5. Stem cell regulation: Implications when differentiated cells regulate symmetric stem cell division.

    PubMed

    Høyem, Marte Rørvik; Måløy, Frode; Jakobsen, Per; Brandsdal, Bjørn Olav

    2015-09-07

    We use a mathematical model to show that if symmetric stem cell division is regulated by differentiated cells, then changes in the population dynamics of the differentiated cells can lead to changes in the population dynamics of the stem cells. More precisely, the relative fitness of the stem cells can be affected by modifying the death rate of the differentiated cells. This result is interesting because stem cells are less sensitive than differentiated cells to environmental factors, such as medical therapy. Our result implies that stem cells can be manipulated indirectly by medical treatments that target the differentiated cells.

  6. [Cell cycle regulation in cancer stem cells].

    PubMed

    Takeishi, Shoichiro

    2015-05-01

    In addition to the properties of self-renewal and multipotency, cancer stem cells share the characteristics of their distinct cell cycle status with somatic stem cells. Cancer stem cells (CSCs) are maintained in a quiescent state with this characteristic conferring resistance to anticancer therapies that target dividing cells. Elucidation of the mechanisms of CSC quiescence might therefore be expected to provide further insight into CSC behaviors and lead to the elimination of cancer. This review summarizes several key regulators of the cell cycle in CSCs as well as attempts to define future challenges in this field, especially from the point of view of the application of our current understandings to the clinical medicine.

  7. Epidermal stem cells and their epigenetic regulation.

    PubMed

    Shen, Qi; Jin, Hongchuan; Wang, Xian

    2013-08-30

    Stem cells play an essential role in embryonic development, cell differentiation and tissue regeneration. Tissue homeostasis in adults is maintained by adult stem cells resident in the niches of different tissues. As one kind of adult stem cell, epidermal stem cells have the potential to generate diversified types of progeny cells in the skin. Although its biology is still largely unclarified, epidermal stem cells are widely used in stem cell research and regenerative medicine given its easy accessibility and pluripotency. Despite the same genome, cells within an organism have different fates due to the epigenetic regulation of gene expression. In this review, we will briefly discuss the current understanding of epigenetic modulation in epidermal stem cells.

  8. Notch regulation of gastrointestinal stem cells.

    PubMed

    Demitrack, Elise S; Samuelson, Linda C

    2016-09-01

    The gastrointestinal (GI) tract epithelium is continuously replenished by actively cycling stem and progenitor cells. These cell compartments are regulated to balance proliferation and stem cell renewal with differentiation into the various mature cell types to maintain tissue homeostasis. In this topical review we focus on the role of the Notch signalling pathway to regulate GI stem cell function in adult small intestine and stomach. We first present the current view of stem and progenitor cell populations in these tissues and then summarize the studies that have established the Notch pathway as a key regulator of gastric and intestinal stem cell function. Notch signalling has been shown to be a niche factor required for maintenance of GI stem cells in both tissues. In addition, Notch has been described to regulate epithelial cell differentiation. Recent studies have revealed key similarities and differences in how Notch regulates stem cell function in the stomach compared to intestine. We summarize the literature regarding Notch regulation of GI stem cell proliferation and differentiation, highlighting tissue-specific functions to compare and contrast Notch in the stomach and intestine. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  9. Notch regulation of gastrointestinal stem cells

    PubMed Central

    Demitrack, Elise S.

    2016-01-01

    Abstract The gastrointestinal (GI) tract epithelium is continuously replenished by actively cycling stem and progenitor cells. These cell compartments are regulated to balance proliferation and stem cell renewal with differentiation into the various mature cell types to maintain tissue homeostasis. In this topical review we focus on the role of the Notch signalling pathway to regulate GI stem cell function in adult small intestine and stomach. We first present the current view of stem and progenitor cell populations in these tissues and then summarize the studies that have established the Notch pathway as a key regulator of gastric and intestinal stem cell function. Notch signalling has been shown to be a niche factor required for maintenance of GI stem cells in both tissues. In addition, Notch has been described to regulate epithelial cell differentiation. Recent studies have revealed key similarities and differences in how Notch regulates stem cell function in the stomach compared to intestine. We summarize the literature regarding Notch regulation of GI stem cell proliferation and differentiation, highlighting tissue‐specific functions to compare and contrast Notch in the stomach and intestine. PMID:26848053

  10. Common stemness regulators of embryonic and cancer stem cells

    PubMed Central

    Hadjimichael, Christiana; Chanoumidou, Konstantina; Papadopoulou, Natalia; Arampatzi, Panagiota; Papamatheakis, Joseph; Kretsovali, Androniki

    2015-01-01

    Pluripotency of embryonic stem cells (ESCs) and induced pluripotent stem cells is regulated by a well characterized gene transcription circuitry. The circuitry is assembled by ESC specific transcription factors, signal transducing molecules and epigenetic regulators. Growing understanding of stem-like cells, albeit of more complex phenotypes, present in tumors (cancer stem cells), provides a common conceptual and research framework for basic and applied stem cell biology. In this review, we highlight current results on biomarkers, gene signatures, signaling pathways and epigenetic regulators that are common in embryonic and cancer stem cells. We discuss their role in determining the cell phenotype and finally, their potential use to design next generation biological and pharmaceutical approaches for regenerative medicine and cancer therapies. PMID:26516408

  11. Metaboloepigenetic Regulation of Pluripotent Stem Cells

    PubMed Central

    Harvey, Alexandra J.; Gardner, David K.

    2016-01-01

    The differentiation of pluripotent stem cells is associated with extensive changes in metabolism, as well as widespread remodeling of the epigenetic landscape. Epigenetic regulation is essential for the modulation of differentiation, being responsible for cell type specific gene expression patterns through the modification of DNA and histones, thereby establishing cell identity. Each cell type has its own idiosyncratic pattern regarding the use of specific metabolic pathways. Rather than simply being perceived as a means of generating ATP and building blocks for cell growth and division, cellular metabolism can directly influence cellular regulation and the epigenome. Consequently, the significance of nutrients and metabolites as regulators of differentiation is central to understanding how cells interact with their immediate environment. This review serves to integrate studies on pluripotent stem cell metabolism, and the regulation of DNA methylation and acetylation and identifies areas in which current knowledge is limited. PMID:26839556

  12. Stem cell technologies: regulation, patents and problems.

    PubMed

    Then, Shih-Ning

    2004-11-01

    Human embryonic stem cell research promises to deliver in the future a whole range of therapeutic treatments, but currently governments in different jurisdictions must try to regulate this burgeoning area. Part of the problem has been, and continues to be, polarised community opinion on the use of human embryonic stem cells for research. This article compares the approaches of the Australian, United Kingdom and United States governments in regulating human embryonic stem cell research. To date, these governments have approached the issue through implementing legislation or policy to control research. Similarly, the three jurisdictions have viewed the patentability of human embryonic stem cell technologies in their own ways with different policies being adopted by the three patent offices. This article examines these different approaches and discusses the inevitable concerns that have been raised due to the lack of a universal approach in relation to the regulation of research; the patenting of stem cell technologies; and the effects patents granted are having on further human embryonic stem cell research.

  13. Regulation of germ line stem cell homeostasis

    PubMed Central

    Garcia, T.X.; Hofmann, M.C.

    2015-01-01

    Mammalian spermatogenesis is a complex process in which spermatogonial stem cells of the testis (SSCs) develop to ultimately form spermatozoa. In the seminiferous epithelium, SSCs self-renew to maintain the pool of stem cells throughout life, or they differentiate to generate a large number of germ cells. A balance between SSC self-renewal and differentiation is therefore essential to maintain normal spermatogenesis and fertility. Stem cell homeostasis is tightly regulated by signals from the surrounding microenvironment, or SSC niche. By physically supporting the SSCs and providing them with these extrinsic molecules, the Sertoli cell is the main component of the niche. Earlier studies have demonstrated that GDNF and CYP26B1, produced by Sertoli cells, are crucial for self-renewal of the SSC pool and maintenance of the undifferentiated state. Down-regulating the production of these molecules is therefore equally important to allow germ cell differentiation. We propose that NOTCH signaling in Sertoli cells is a crucial regulator of germ cell fate by counteracting these stimulatory factors to maintain stem cell homeostasis. Dysregulation of this essential niche component can lead by itself to sterility or facilitate testicular cancer development.

  14. Cartilage stem cells: regulation of differentiation.

    PubMed

    Solursh, M

    1989-01-01

    The developing limb bud is a useful source of cartilage stem cells for studies on the regulation of chondrogenesis. In high density cultures these cells can progress through all stages of chondrogenesis to produce mineralized hypertrophic cartilage. If the cells are maintained in a spherical shape, single stem cells can progress through a similar sequence. The actin cytoskeleton is implicated in the regulation of chondrogenesis since conditions that favor its disruption promote chondrogenesis and conditions that favor actin assembly inhibit chondrogenesis. Since a number of extracellular matrix receptors mediate effects of the extracellular matrix on cytoskeletal organization and some of these receptors are developmentally regulated, it is proposed that matrix receptor expression plays a central role in the divergence of connective tissue cells during development.

  15. MicroRNAs: key regulators of stem cells.

    PubMed

    Gangaraju, Vamsi K; Lin, Haifan

    2009-02-01

    The hallmark of a stem cell is its ability to self-renew and to produce numerous differentiated cells. This unique property is controlled by dynamic interplays between extrinsic signalling, epigenetic, transcriptional and post-transcriptional regulations. Recent research indicates that microRNAs (miRNAs) have an important role in regulating stem cell self-renewal and differentiation by repressing the translation of selected mRNAs in stem cells and differentiating daughter cells. Such a role has been shown in embryonic stem cells, germline stem cells and various somatic tissue stem cells. These findings reveal a new dimension of gene regulation in controlling stem cell fate and behaviour.

  16. Cell cycle regulation by microRNAs in stem cells.

    PubMed

    Wang, Yangming; Blelloch, Robert

    2011-01-01

    The ability to self-renew and to differentiate into at least one-cell lineage defines a stem cell. Self-renewal is a process by which stem cells proliferate without differentiation. Proliferation is achieved through a series of highly regulated events of the cell cycle. MicroRNAs (miRNAs) are a class of short noncoding RNAs whose importance in these events is becoming increasingly appreciated. In this chapter, we discuss the role of miRNAs in regulating the cell cycle in various stem cells with a focus on embryonic stem cells. We also present the evidence indicating that cell cycle-regulating miRNAs are incorporated into a large regulatory network to control the self-renewal of stem cells by inducing or inhibiting differentiation. In addition, we discuss the function of cell cycle-regulating miRNAs in cancer.

  17. Redox regulation in cancer stem cells

    USDA-ARS?s Scientific Manuscript database

    Reactive oxygen species (ROS) and ROS-dependent (redox regulation) signaling pathways and transcriptional activities are thought to be critical in stem cell self-renewal and differentiation during growth and organogenesis. Aberrant ROS burst and dysregulation of those ROS-dependent cellular processe...

  18. Epigenetic Mechanisms Regulating Mesenchymal Stem Cell Differentiation

    PubMed Central

    Pérez-Campo, Flor M.; Riancho, José A.

    2015-01-01

    Human Mesenchymal Stem Cells (hMSCs) have emerged in the last few years as one of the most promising therapeutic cell sources and, in particular, as an important tool for regenerative medicine of skeletal tissues. Although they present a more restricted potency than Embryonic Stem (ES) cells, the use of hMCS in regenerative medicine avoids many of the drawbacks characteristic of ES cells or induced pluripotent stem cells. The challenge in using these cells lies into developing precise protocols for directing cellular differentiation to generate a specific cell lineage. In order to achieve this goal, it is of the upmost importance to be able to control de process of fate decision and lineage commitment. This process requires the coordinate regulation of different molecular layers at transcriptional, posttranscriptional and translational levels. At the transcriptional level, switching on and off different sets of genes is achieved not only through transcriptional regulators, but also through their interplay with epigenetic modifiers. It is now well known that epigenetic changes take place in an orderly way through development and are critical in the determination of lineage-specific differentiation. More importantly, alteration of these epigenetic changes would, in many cases, lead to disease generation and even tumour formation. Therefore, it is crucial to elucidate how epigenetic factors, through their interplay with transcriptional regulators, control lineage commitment in hMSCs. PMID:27019612

  19. Epigenetic Regulation of Hematopoietic Stem Cells

    PubMed Central

    Sharma, Shilpa; Gurudutta, Gangenahalli

    2016-01-01

    Hematopoietic stem cells are endowed with a distinct potential to bolster self-renewal and to generate progeny that differentiate into mature cells of myeloid and lymphoid lineages. Both hematopoietic stem cells and mature cells have the same genome, but their gene expression is controlled by an additional layer of epigenetics such as DNA methylation and post-translational histone modifications, enabling each cell-type to acquire various forms and functions. Until recently, several studies have largely focussed on the transcription factors andniche factors for the understanding of the molecular mechanisms by which hematopoietic cells replicate and differentiate. Several lines of emerging evidence suggest that epigenetic modifications eventually result in a defined chromatin structure and an “individual” gene expression pattern, which play an essential role in the regulation of hematopoietic stem cell self-renewal and differentiation. Distinct epigenetic marks decide which sets of genes may be expressed and which genes are kept silent. Epigenetic mechanisms are interdependent and ensure lifelong production of blood and bone marrow, thereby contributing to stem cell homeostasis. The epigenetic analysis of hematopoiesis raises the exciting possibility that chromatin structure is dynamic enough for regulated expression of genes. Though controlled chromatin accessibility plays an essential role in maintaining blood homeostasis; mutations in chromatin impacts on the regulation of genes critical to the development of leukemia. In this review, we explored the contribution of epigenetic machinery which has implications for the ramification of molecular details of hematopoietic self-renewal for normal development and underlying events that potentially co-operate to induce leukemia. PMID:27426084

  20. Redox Regulation in Cancer Stem Cells

    PubMed Central

    Ding, Shijie; Li, Chunbao; Cheng, Ninghui; Cui, Xiaojiang; Xu, Xinglian; Zhou, Guanghong

    2015-01-01

    Reactive oxygen species (ROS) and ROS-dependent (redox regulation) signaling pathways and transcriptional activities are thought to be critical in stem cell self-renewal and differentiation during growth and organogenesis. Aberrant ROS burst and dysregulation of those ROS-dependent cellular processes are strongly associated with human diseases including many cancers. ROS levels are elevated in cancer cells partially due to their higher metabolism rate. In the past 15 years, the concept of cancer stem cells (CSCs) has been gaining ground as the subpopulation of cancer cells with stem cell-like properties and characteristics have been identified in various cancers. CSCs possess low levels of ROS and are responsible for cancer recurrence after chemotherapy or radiotherapy. Unfortunately, how CSCs control ROS production and scavenging and how ROS-dependent signaling pathways contribute to CSCs function remain poorly understood. This review focuses on the role of redox balance, especially in ROS-dependent cellular processes in cancer stem cells (CSCs). We updated recent advances in our understanding of ROS generation and elimination in CSCs and their effects on CSC self-renewal and differentiation through modulating signaling pathways and transcriptional activities. The review concludes that targeting CSCs by manipulating ROS metabolism/dependent pathways may be an effective approach for improving cancer treatment. PMID:26273424

  1. Epigenetic regulation of hematopoietic stem cell aging

    SciTech Connect

    Beerman, Isabel

    2014-12-10

    Aging is invariably associated with alterations of the hematopoietic stem cell (HSC) compartment, including loss of functional capacity, altered clonal composition, and changes in lineage contribution. Although accumulation of DNA damage occurs during HSC aging, it is unlikely such consistent aging phenotypes could be solely attributed to changes in DNA integrity. Another mechanism by which heritable traits could contribute to the changes in the functional potential of aged HSCs is through alterations in the epigenetic landscape of adult stem cells. Indeed, recent studies on hematopoietic stem cells have suggested that altered epigenetic profiles are associated with HSC aging and play a key role in modulating the functional potential of HSCs at different stages during ontogeny. Even small changes of the epigenetic landscape can lead to robustly altered expression patterns, either directly by loss of regulatory control or through indirect, additive effects, ultimately leading to transcriptional changes of the stem cells. Potential drivers of such changes in the epigenetic landscape of aged HSCs include proliferative history, DNA damage, and deregulation of key epigenetic enzymes and complexes. This review will focus largely on the two most characterized epigenetic marks – DNA methylation and histone modifications – but will also discuss the potential role of non-coding RNAs in regulating HSC function during aging.

  2. [Genetic regulation of plant shoot stem cells].

    PubMed

    Al'bert, E V; Ezhova, T A

    2013-02-01

    This article describes the main features of plant stem cells and summarizes the results of studies of the genetic control of stem cell maintenance in the apical meristem of the shoot. It is demonstrated that the WUS-CLV gene system plays a key role in the maintenance of shoot apical stem cells and the formation of adventitious buds and somatic embryos. Unconventional concepts of plant stem cells are considered.

  3. Stem cell frontiers: science, ethics and regulation.

    PubMed

    Hearn, John

    2007-08-01

    The isolation of human stem cells and the cloning of "Dolly" in the late 1990s, based on primate and other animal studies in the previous 20 years, created an explosion of interest that continues with daily reports in much of the world's press. The science has progressed steadily but not always smoothly, with promising discoveries in the potency and flexibility of cells derived from embryonic, umbilical cord and adult tissues. The promise of a revolutionary new era in health and medical sciences and systems requires careful scientific method, ethical debate and supportive legal and regulatory frameworks to achieve success. The frontiers of the science are focusing on the regulation of cell lineage choice and the development of designer stem cells for therapeutic cloning; the ethical debate focuses on the special status of the human embryo and the pathways to applications; while legal and regulatory frameworks differ around the world. There is some risk that the promises are overtaking the reality of progress, with the rush for results and premature offering of dubious remedies compromising scientific method and credibility. Stem cells should not be the snake oil of our times, nor should short cuts and short sell promises, fuelled by illusions of fame and fortune, risk the trust of the public in science and medicine.

  4. Stem cells, telomerase regulation and the hypoxic state.

    PubMed

    Mathews, Juanita; Davy, Philip M C; Gardner, Lauren H; Allsopp, Richard C

    2016-01-01

    The cellular response to a hypoxic environment is regulated by hypoxia inducible factors. Hypoxia inducible factor 1 alpha (Hif1alpha) in particular, is tightly regulated by the hypoxic environment in most cells, and plays an important role in regulating the stress response of cells to hypoxia. Interestingly, substantial observations are now emerging that point to an important role for Hif1alpha in stem cells, including embryonic stem cells, neuronal stem cells and hematopoietic stem cells. Notably, Hif1alpha has been shown to enhance self renewal of stem cells, mediate a shift to glycolytic metabolism, and promote telomerase expression.

  5. Integrating physiological regulation with stem cell and tissue homeostasis

    PubMed Central

    Nakada, Daisuke; Levi, Boaz P.; Morrison, Sean J.

    2015-01-01

    Summary Stem cells are uniquely able to self-renew, to undergo multilineage differentiation, and to persist throughout life in a number of tissues. Stem cells are regulated by a combination of shared and tissue-specific mechanisms and are distinguished from restricted progenitors by differences in transcriptional and epigenetic regulation. Emerging evidence suggests that other aspects of cellular physiology, including mitosis, signal transduction, and metabolic regulation also differ between stem cells and their progeny. These differences may allow stem cells to be regulated independently of differentiated cells in response to circadian rhythms, changes in metabolism, diet, exercise, mating, aging, infection, and disease. This allows stem cells to sustain homeostasis or to remodel relevant tissues in response to physiological change. Stem cells are therefore not only regulated by short-range signals that maintain homeostasis within their tissue of origin, but also by long-range signals that integrate stem cell function with systemic physiology. PMID:21609826

  6. Nanotechnology in the regulation of stem cell behavior.

    PubMed

    Wu, King-Chuen; Tseng, Ching-Li; Wu, Chi-Chang; Kao, Feng-Chen; Tu, Yuan-Kun; C So, Edmund; Wang, Yang-Kao

    2013-10-01

    Stem cells are known for their potential to repair damaged tissues. The adhesion, growth and differentiation of stem cells are likely controlled by the surrounding microenvironment which contains both chemical and physical cues. Physical cues in the microenvironment, for example, nanotopography, were shown to play important roles in stem cell fate decisions. Thus, controlling stem cell behavior by nanoscale topography has become an important issue in stem cell biology. Nanotechnology has emerged as a new exciting field and research from this field has greatly advanced. Nanotechnology allows the manipulation of sophisticated surfaces/scaffolds which can mimic the cellular environment for regulating cellular behaviors. Thus, we summarize recent studies on nanotechnology with applications to stem cell biology, including the regulation of stem cell adhesion, growth, differentiation, tracking and imaging. Understanding the interactions of nanomaterials with stem cells may provide the knowledge to apply to cell-scaffold combinations in tissue engineering and regenerative medicine.

  7. Nanotechnology in the regulation of stem cell behavior

    NASA Astrophysics Data System (ADS)

    Wu, King-Chuen; Tseng, Ching-Li; Wu, Chi-Chang; Kao, Feng-Chen; Tu, Yuan-Kun; So, Edmund C.; Wang, Yang-Kao

    2013-10-01

    Stem cells are known for their potential to repair damaged tissues. The adhesion, growth and differentiation of stem cells are likely controlled by the surrounding microenvironment which contains both chemical and physical cues. Physical cues in the microenvironment, for example, nanotopography, were shown to play important roles in stem cell fate decisions. Thus, controlling stem cell behavior by nanoscale topography has become an important issue in stem cell biology. Nanotechnology has emerged as a new exciting field and research from this field has greatly advanced. Nanotechnology allows the manipulation of sophisticated surfaces/scaffolds which can mimic the cellular environment for regulating cellular behaviors. Thus, we summarize recent studies on nanotechnology with applications to stem cell biology, including the regulation of stem cell adhesion, growth, differentiation, tracking and imaging. Understanding the interactions of nanomaterials with stem cells may provide the knowledge to apply to cell-scaffold combinations in tissue engineering and regenerative medicine.

  8. Mechanical regulation of mesenchymal stem cell differentiation.

    PubMed

    Steward, Andrew J; Kelly, Daniel J

    2015-12-01

    Biophysical cues play a key role in directing the lineage commitment of mesenchymal stem cells or multipotent stromal cells (MSCs), but the mechanotransductive mechanisms at play are still not fully understood. This review article first describes the roles of both substrate mechanics (e.g. stiffness and topography) and extrinsic mechanical cues (e.g. fluid flow, compression, hydrostatic pressure, tension) on the differentiation of MSCs. A specific focus is placed on the role of such factors in regulating the osteogenic, chondrogenic, myogenic and adipogenic differentiation of MSCs. Next, the article focuses on the cellular components, specifically integrins, ion channels, focal adhesions and the cytoskeleton, hypothesized to be involved in MSC mechanotransduction. This review aims to illustrate the strides that have been made in elucidating how MSCs sense and respond to their mechanical environment, and also to identify areas where further research is needed.

  9. Patterning as a signature of human epidermal stem cell regulation

    PubMed Central

    Klein, Allon M.; Nikolaidou-Neokosmidou, Varvara; Doupé, David P.; Jones, Philip H.; Simons, Benjamin D.

    2011-01-01

    Understanding how stem cells are regulated in adult tissues is a major challenge in cell biology. In the basal layer of human epidermis, clusters of almost quiescent stem cells are interspersed with proliferating and differentiating cells. Previous studies have shown that the proliferating cells follow a pattern of balanced stochastic cell fate. This behaviour enables them to maintain homeostasis, while stem cells remain confined to their quiescent clusters. Intriguingly, these clusters reappear spontaneously in culture, suggesting that they may play a functional role in stem cell auto-regulation. We propose a model of pattern formation that explains how clustering could regulate stem cell activity in homeostatic tissue through contact inhibition and stem cell aggregation. PMID:21632613

  10. The regulation of hematopoietic stem cell populations

    PubMed Central

    Mayani, Hector

    2016-01-01

    Evidence presented over the last few years indicates that the hematopoietic stem cell (HSC) compartment comprises not just one but a number of different cell populations. Based on HSCs’ proliferation and engraftment potential, it has been suggested that there are two classes of HSC, with long- and short-term engraftment potential. HSC heterogeneity seems to involve differentiation capacities as well, since it has been shown that some HSC clones are able to give rise to both myeloid and lymphoid progeny, whereas others are lymphoid deficient. It has been recognized that HSC function depends on intrinsic cell regulators, which are modulated by external signals. Among the former, we can include transcription factors and non-coding RNAs as well as epigenetic modifiers. Among the latter, cytokines and extracellular matrix molecules have been implicated. Understanding the elements and mechanisms that regulate HSC populations is of significant relevance both in biological and in clinical terms, and research in this area still has to face several complex and exciting challenges. PMID:27408695

  11. Regulation of breast cancer stem cell features.

    PubMed

    Czerwinska, Patrycja; Kaminska, Bozena

    2015-01-01

    Cancer stem cells (CSCs) are rare, tumour-initiating cells that exhibit stem cell properties: capacity of self-renewal, pluripotency, highly tumorigenic potential, and resistance to therapy. Cancer stem cells have been characterised and isolated from many cancers, including breast cancer. Developmental pathways, such as the Wnt/β-catenin, Notch/γ-secretase/Jagged, Shh (sonic hedgehog), and BMP signalling pathways, which direct proliferation and differentiation of normal stem cells, have emerged as major signalling pathways that contribute to the self-renewal of stem and/or progenitor cells in a variety of organs and cancers. Deregulation of these signalling pathways is frequently linked to an epithelial-mesenchymal transition (EMT), and breast CSCs often possess properties of cells that have undergone the EMT process. Signalling networks mediated by microRNAs and EMT-inducing transcription factors tie the EMT process to regulatory networks that maintain "stemness". Recent studies have elucidated epigenetic mechanisms that control pluripotency and stemness, which allows an assessment on how embryonic and normal tissue stem cells are deregulated during cancerogenesis to give rise to CSCs. Epigenetic-based mechanisms are reversible, and the possibility of "resetting" the abnormal cancer epigenome by applying pharmacological compounds targeting epigenetic enzymes is a promising new therapeutic strategy. Chemoresistance of CSCs is frequently driven by various mechanisms, including aberrant expression/activity of ABC transporters, aldehyde dehydrogenase and anti-oncogenic proteins (i.e. BCL2, B-cell lymphoma-2), enhanced DNA damage response, activation of pro-survival signalling pathways, and epigenetic deregulations. Despite controversy surrounding the CSC hypothesis, there is substantial evidence for their role in cancer, and a number of drugs intended to specifically target CSCs have entered clinical trials.

  12. Concise Review: Mechanisms of Quiescent Hair Follicle Stem Cell Regulation.

    PubMed

    Yi, Rui

    2017-08-30

    Maintaining a pool of adult stem cells is essential for tissue homeostasis and wound repair. In mammalian tissues, notably hair follicles, blood, and muscle, stem cells acquire quiescence and infrequently divide for self-renewal. Mechanistic understanding of stem cell quiescence is critical for applying these multipotent cells in regenerative medicine and interrogating their roles in human diseases such as cancer. Quiescent and dividing epithelial stem cells located in hair follicle are conspicuously organized in a spatiotemporally specific manner, allowing them to be studied at a considerable depth. Recent advancements in mouse genetics, genomics, and imaging have revealed unprecedented insights into establishment, maintenance, and regulation of quiescent hair follicle stem cells. This concise review summarizes the progress with a focus on mechanisms mediated by signaling pathways and transcription factors and discusses their implications in the understanding of stem cell biology. Stem Cells 2017. © 2017 AlphaMed Press.

  13. Breast cancer stem cells are regulated by mesenchymal stem cells through cytokine networks

    PubMed Central

    Liu, Suling; Ginestier, Christophe; Ou, Sing J.; Clouthier, Shawn G.; Patel, Shivani H.; Monville, Florence; Korkaya, Hasan; Heath, Amber; Dutcher, Julie; Kleer, Celina G.; Jung, Younghun; Dontu, Gabriela; Taichman, Russell; Wicha, Max S.

    2011-01-01

    We have utilized in vitro and mouse xenograft models to examine the interaction between breast cancer stem cells (CSCs) and bone marrow derived mesenchymal stem cells (MSCs). We demonstrate that both of these cell populations are organized in a cellular hierarchy in which primitive aldehyde dehydrogenase (ALDH) expressing mesenchymal cells regulate breast CSCs through cytokine loops involving IL6 and CXCL7. In NOD/SCID mice, labeled MSCs introduced into the tibia traffic to sites of growing breast tumor xenografts where they accelerate tumor growth by increasing the breast cancer stem cell population. Utilizing immunochemistry, we identified “MSC-CSC niches” in these tumor xenografts as well as in frozen sections from primary human breast cancers. Bone marrow derived mesenchymal stem cell may accelerate human breast tumor growth by generating cytokine networks that regulate the cancer stem cell population. PMID:21224357

  14. Notch signaling regulates gastric antral LGR5 stem cell function.

    PubMed

    Demitrack, Elise S; Gifford, Gail B; Keeley, Theresa M; Carulli, Alexis J; VanDussen, Kelli L; Thomas, Dafydd; Giordano, Thomas J; Liu, Zhenyi; Kopan, Raphael; Samuelson, Linda C

    2015-10-14

    The major signaling pathways regulating gastric stem cells are unknown. Here we report that Notch signaling is essential for homeostasis of LGR5(+) antral stem cells. Pathway inhibition reduced proliferation of gastric stem and progenitor cells, while activation increased proliferation. Notch dysregulation also altered differentiation, with inhibition inducing mucous and endocrine cell differentiation while activation reduced differentiation. Analysis of gastric organoids demonstrated that Notch signaling was intrinsic to the epithelium and regulated growth. Furthermore, in vivo Notch manipulation affected the efficiency of organoid initiation from glands and single Lgr5-GFP stem cells, suggesting regulation of stem cell function. Strikingly, constitutive Notch activation in LGR5(+) stem cells induced tissue expansion via antral gland fission. Lineage tracing using a multi-colored reporter demonstrated that Notch-activated stem cells rapidly generate monoclonal glands, suggesting a competitive advantage over unmanipulated stem cells. Notch activation was associated with increased mTOR signaling, and mTORC1 inhibition normalized NICD-induced increases in proliferation and gland fission. Chronic Notch activation induced undifferentiated, hyper-proliferative polyps, suggesting that aberrant activation of Notch in gastric stem cells may contribute to gastric tumorigenesis. © 2015 The Authors.

  15. Regulated GDNF Delivery in Vivo Using Neural Stem Cells

    DTIC Science & Technology

    2006-04-01

    which do not kill cell bodies within the striatum but induce retrograde death of dopamine bodies in the brain stem showed a level of survival and...Neural Stem Cells PRINCIPAL INVESTIGATOR: Clive Svendsen, Ph.D. CONTRACTING ORGANIZATION: University of Wisconsin...Regulated GDNF Delivery in Vivo Using Neural Stem Cells 5b. GRANT NUMBER DAMD17-03-1-0122 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT

  16. Regulated GDNF Delivery In Vivo using Neural Stem Cells

    DTIC Science & Technology

    2005-04-01

    attached as Appendix 2. Body Task 1. To produce rat and monkey neural stem cells which secrete GDNF under an inducible promoter. a. Assess and optimize GDNF...AD Award Number: DAMD17-03-1-0122 TITLE: Regulated GDNF Delivery In Vivo Using Neural Stem Cells PRINCIPAL INVESTIGATOR: Clive N. Svendsen, Ph.D...analysis of 4 rats for PET. This system is now ready for the new stem cell transplants and carrying out the experiments outlined in year three which

  17. Are stem cells drugs? The regulation of stem cell research and development.

    PubMed

    Rosen, Michael R

    2006-10-31

    Stem cell research and its clinical application have become political, social, and medical lightning rods, polarizing opinion among members of the lay community and among medical/scientific professionals. A potpourri of opinion, near-anecdotal observation, and scientifically sound data has sown confusion in ways rarely seen in the medical arts and sciences. A major issue is regulation, with different aspects of stem cell research falling within the purview of different government agencies and local offices. An overarching clearinghouse to review the field and recommend policy is lacking. In the following pages, I touch on the societal framework for regulation, the known and potential risks and benefits of cardiovascular stem cell therapies, whether stem cells should be regulated as drugs or in analogy to drugs, and if there is to be regulation, then by whom. In so doing, I refer to the stem cell literature only as it relates to the discussion of regulation because this is not a review of stem cell research; it is an opinion regarding regulation.

  18. Cell cycle regulation of hematopoietic stem or progenitor cells.

    PubMed

    Hao, Sha; Chen, Chen; Cheng, Tao

    2016-05-01

    The highly regulated process of blood production is achieved through the hierarchical organization of hematopoietic stem cell (HSC) subsets and their progenies, which differ in self-renewal and differentiation potential. Genetic studies in mice have demonstrated that cell cycle is tightly controlled by the complex interplay between extrinsic cues and intrinsic regulatory pathways involved in HSC self-renewal and differentiation. Deregulation of these cellular programs may transform HSCs or hematopoietic progenitor cells (HPCs) into disease-initiating stem cells, and can result in hematopoietic malignancies such as leukemia. While previous studies have shown roles for some cell cycle regulators and related signaling pathways in HSCs and HPCs, a more complete picture regarding the molecular mechanisms underlying cell cycle regulation in HSCs or HPCs is lacking. Based on accumulated studies in this field, the present review introduces the basic components of the cell cycle machinery and discusses their major cellular networks that regulate the dormancy and cell cycle progression of HSCs. Knowledge on this topic would help researchers and clinicians to better understand the pathogenesis of relevant blood disorders and to develop new strategies for therapeutic manipulation of HSCs.

  19. Integrin alpha 6 regulates glioblastoma stem cells

    PubMed Central

    Lathia, Justin D.; Gallagher, Joseph; Heddleston, John M.; Wang, Jialiang; Eyler, Christine E.; MacSwords, Jennifer; Wu, Qiulian; Vasanji, Amit; McLendon, Roger E.; Hjelmeland, Anita B.; Rich, Jeremy N.

    2010-01-01

    Summary Cancer stem cells (CSCs) are a subpopulation of tumor cells suggested to be critical for tumor maintenance, metastasis, and therapeutic resistance. Prospective identification and targeting of CSCs are therefore priorities for the development of novel therapeutic paradigms. While CSC enrichment has been achieved with cell surface proteins including CD133 (Prominin-1), the roles of current CSC markers in tumor maintenance remain unclear. We examined the glioblastoma stem cell (GSC) perivascular microenvironment in patient specimens to identify enrichment markers with a functional significance and identified integrin α6 as a candidate. Integrin α6 is co-expressed with conventional GSC markers and enriches for GSCs. Targeting integrin α6 in GSCs inhibits self-renewal, proliferation, and tumor formation capacity. Our results provide evidence that GSCs express high levels of integrin α6, which can not only serve as an enrichment marker but also as a promising anti-glioblastoma therapy. PMID:20452317

  20. Stem cell aging: mechanisms, regulators and therapeutic opportunities

    PubMed Central

    Oh, Juhyun; Lee, Yang David; Wagers, Amy J

    2014-01-01

    Aging tissues experience a progressive decline in homeostatic and regenerative capacities, which has been attributed to degenerative changes in tissue-specific stem cells, stem cell niches and systemic cues that regulate stem cell activity. Understanding the molecular pathways involved in this age-dependent deterioration of stem cell function will be critical for developing new therapies for diseases of aging that target the specific causes of age-related functional decline. Here we explore key molecular pathways that are commonly perturbed as tissues and stem cells age and degenerate. We further consider experimental evidence both supporting and refuting the notion that modulation of these pathways per se can reverse aging phenotypes. Finally, we ask whether stem cell aging establishes an epigenetic ‘memory’ that is indelibly written or one that can be reset. PMID:25100532

  1. Corneal epithelial stem cells: deficiency and regulation.

    PubMed

    Secker, Genevieve A; Daniels, Julie T

    2008-09-01

    The corneal epithelium is continuously renewed by a population of stem cells that reside in the corneoscleral junction, otherwise known as the limbus. These limbal epithelial stem cells (LESC) are imperative for corneal maintenance with deficiencies leading to in-growth of conjunctival cells, neovascularisation of the corneal stroma and eventual corneal opacity and visual loss. One such disease that has traditionally been thought to be due to LESC deficiency is aniridia, a pan-ocular congenital eye disease due to mutations in the PAX6 gene. Corneal changes or aniridia related keratopathy (ARK) seen in aniridia are typical of LESC deficiency. However, the pathophysiology behind ARK is still ill defined, with current theories suggesting it may be caused by a deficiency in the stem cell niche and adjacent corneal stroma, with altered wound healing responses also playing a role (Ramaesh et al, International Journal of Biochemistry & Cell Biology 37:547-557, 2005) or abnormal epidermal differentiation of LESC (Li et al., The Journal of Pathology 214:9, 2008). PAX6 is considered the master control gene for the eye and is required for normal eye development with expression continuing in the adult cornea, thus inferring a role for corneal repair and regeneration (Sivak et al., Developments in Biologicals 222:41-54, 2000). Studies of models of Pax6 deficiency, such as the small eyed (sey) mouse, should help to reveal the intrinsic and extrinsic mechanisms involved in normal LESC function.

  2. Neural stem cell progeny regulate stem cell death in a Notch and Hox dependent manner

    PubMed Central

    Arya, R; Sarkissian, T; Tan, Y; White, K

    2015-01-01

    Cell death is a prevalent, well-controlled and fundamental aspect of development, particularly in the nervous system. In Drosophila, specific neural stem cells are eliminated by apoptosis during embryogenesis. In the absence of apoptosis, these stem cells continue to divide, resulting in a dramatically hyperplastic central nervous system and adult lethality. Although core cell death pathways have been well described, the spatial, temporal and cell identity cues that activate the cell death machinery in specific cells are largely unknown. We identified a cis-regulatory region that controls the transcription of the cell death activators reaper, grim and sickle exclusively in neural stem cells. Using a reporter generated from this regulatory region, we found that Notch activity is required for neural stem cell death. Notch regulates the expression of the abdominalA homeobox protein, which provides important spatial cues for death. Importantly, we show that pro-apoptotic Notch signaling is activated by the Delta ligand expressed on the neighboring progeny of the stem cell. Thus we identify a previously undescribed role for progeny in regulating the proper developmental death of their parental stem cells. PMID:25633198

  3. European regulation for therapeutic use of stem cells.

    PubMed

    Ferry, Nicolas

    2017-01-01

    The regulation for the use of stem cells has evolved during the past decade with the aim of ensuring a high standard of quality and safety for human derived products throughout Europe to comply with the provision of the Lisbon treaty. To this end, new regulations have been issued and the regulatory status of stem cells has been revised. Indeed, stem cells used for therapeutic purposes can now be classified as a cell preparation, or as advanced therapy medicinal products depending on the clinical indication and on the procedure of cell preparation. Furthermore, exemptions to the European regulation are applicable for stem cells prepared and used within the hospital. The aim of this review is to give the non-specialized reader a broad overview of this particular regulatory landscape.

  4. REST regulation of gene networks in adult neural stem cells.

    PubMed

    Mukherjee, Shradha; Brulet, Rebecca; Zhang, Ling; Hsieh, Jenny

    2016-11-07

    Adult hippocampal neural stem cells generate newborn neurons throughout life due to their ability to self-renew and exist as quiescent neural progenitors (QNPs) before differentiating into transit-amplifying progenitors (TAPs) and newborn neurons. The mechanisms that control adult neural stem cell self-renewal are still largely unknown. Conditional knockout of REST (repressor element 1-silencing transcription factor) results in precocious activation of QNPs and reduced neurogenesis over time. To gain insight into the molecular mechanisms by which REST regulates adult neural stem cells, we perform chromatin immunoprecipitation sequencing and RNA-sequencing to identify direct REST target genes. We find REST regulates both QNPs and TAPs, and importantly, ribosome biogenesis, cell cycle and neuronal genes in the process. Furthermore, overexpression of individual REST target ribosome biogenesis or cell cycle genes is sufficient to induce activation of QNPs. Our data define novel REST targets to maintain the quiescent neural stem cell state.

  5. REST regulation of gene networks in adult neural stem cells

    PubMed Central

    Mukherjee, Shradha; Brulet, Rebecca; Zhang, Ling; Hsieh, Jenny

    2016-01-01

    Adult hippocampal neural stem cells generate newborn neurons throughout life due to their ability to self-renew and exist as quiescent neural progenitors (QNPs) before differentiating into transit-amplifying progenitors (TAPs) and newborn neurons. The mechanisms that control adult neural stem cell self-renewal are still largely unknown. Conditional knockout of REST (repressor element 1-silencing transcription factor) results in precocious activation of QNPs and reduced neurogenesis over time. To gain insight into the molecular mechanisms by which REST regulates adult neural stem cells, we perform chromatin immunoprecipitation sequencing and RNA-sequencing to identify direct REST target genes. We find REST regulates both QNPs and TAPs, and importantly, ribosome biogenesis, cell cycle and neuronal genes in the process. Furthermore, overexpression of individual REST target ribosome biogenesis or cell cycle genes is sufficient to induce activation of QNPs. Our data define novel REST targets to maintain the quiescent neural stem cell state. PMID:27819263

  6. Pannexin 1 regulates postnatal neural stem and progenitor cell proliferation

    PubMed Central

    2012-01-01

    Background Pannexin 1 forms ion and metabolite permeable hexameric channels and is abundantly expressed in the brain. After discovering pannexin 1 expression in postnatal neural stem and progenitor cells we sought to elucidate its functional role in neuronal development. Results We detected pannexin 1 in neural stem and progenitor cells in vitro and in vivo. We manipulated pannexin 1 expression and activity in Neuro2a neuroblastoma cells and primary postnatal neurosphere cultures to demonstrate that pannexin 1 regulates neural stem and progenitor cell proliferation likely through the release of adenosine triphosphate (ATP). Conclusions Permeable to ATP, a potent autocrine/paracine signaling metabolite, pannexin 1 channels are ideally suited to influence the behavior of neural stem and progenitor cells. Here we demonstrate they play a robust role in the regulation of neural stem and progenitor cell proliferation. Endogenous postnatal neural stem and progenitor cells are crucial for normal brain health, and their numbers decline with age. Furthermore, these special cells are highly responsive to neurological injury and disease, and are gaining attention as putative targets for brain repair. Therefore, understanding the fundamental role of pannexin 1 channels in neural stem and progenitor cells is of critical importance for brain health and disease. PMID:22458943

  7. Proinflammatory signaling regulates hematopoietic stem cell emergence

    PubMed Central

    Espín-Palazón, Raquel; Stachura, David L.; Campbell, Clyde A.; García-Moreno, Diana; Cid, Natasha Del; Kim, Albert D.; Candel, Sergio; Meseguer, José; Mulero, Victoriano; Traver, David

    2014-01-01

    Summary Hematopoietic stem cells (HSCs) underlie the production of blood and immune cells for the lifetime of an organism. In vertebrate embryos, HSCs arise from the unique transdifferentiation of hemogenic endothelium comprising the floor of the dorsal aorta during a brief developmental window. To date, this process has not been replicated in vitro from pluripotent precursors, partly because the full complement of required signaling inputs remains to be determined. Here, we show that TNFR2 via TNFα activates the Notch and NF-κB signaling pathways to establish HSC fate, indicating a requirement for inflammatory signaling in HSC generation. We determine that primitive neutrophils are the major source of TNFα, assigning a role for transient innate immune cells in establishing the HSC program. These results demonstrate that proinflammatory signaling, in the absence of infection, is utilized by the developing embryo to generate the lineal precursors of the adult hematopoietic system. PMID:25416946

  8. Transcriptional networks that regulate muscle stem cell function.

    PubMed

    Punch, Vincent G; Jones, Andrew E; Rudnicki, Michael A

    2009-01-01

    Muscle stem cells comprise different populations of stem and progenitor cells found in embryonic and adult tissues. A number of signaling and transcriptional networks are responsible for specification and survival of these cell populations and regulation of their behavior during growth and regeneration. Muscle progenitor cells are mostly derived from the somites of developing embryos, while satellite cells are the progenitor cells responsible for the majority of postnatal growth and adult muscle regeneration. In resting muscle, these stem cells are quiescent, but reenter the cell cycle during their activation, whereby they undergo decisions to self-renew, proliferate, or differentiate and fuse into multinucleated myofibers to repair damaged muscle. Regulation of muscle stem cell activity is under the precise control of a number of extrinsic signaling pathways and active transcriptional networks that dictate their behavior, fate, and regenerative potential. Here, we review the networks responsible for these different aspects of muscle stem cell biology and discuss prevalent parallels between mechanisms regulating the activity of embryonic muscle progenitor cells and adult satellite cells.

  9. Novel Function of Sprouty4 as a Regulator of Stemness and Differentiation of Embryonic Stem Cells

    PubMed Central

    Lee, Jae-Young; Park, Sunghyun; Kim, Kwang-Soo; Ko, Jeong-Jae; Lee, Soohong; Kim, Keun Pil; Park, Kyung-Soon

    2016-01-01

    Sprouty (Spry) genes encode inhibitors of the receptor tyrosine kinase signaling cascade, which plays important roles in stem cells. However, the role of Spry4 in the stemness of embryonic stem cells has not been fully elucidated. Here, we used mouse embryonic stem cells (mESCs) as a model system to investigate the role of Spry4 in the stem cells. Suppression of Spry4 expression results in the decreases of cell proliferation, EB formation and stemness marker expression, suggesting that Spry4 activity is associated with stemness of mESCs. Teratoma assay showed that the cartilage maturation was facilitated in Spry4 knocked down mESCs. Our results suggest that Spry4 is an important regulator of the stemness and differentiation of mESCs. PMID:27660833

  10. Regulation of human stem cell research in South Korea.

    PubMed

    Jung, Kyu Won

    2010-09-01

    Human stem cell research has been performed for many years in South Korea. It has been supported by the South Korean government, like other biomedical research. Like many other countries, human embryonic stem cell research, human adult stem cell research and iPS cell research have been performed in South Korea. The Bioethics and Safety Act is the main law which regulates human stem cell research. It took effect on 1 January 2005. However, this Act does not include all the fields of biomedical research and some provisions were not clear. After Hwang's scandal, there have been heated debates about the revision of the Bioethics and Safety Act. It was revised several times and a new revised version is under consideration now.

  11. Molecular Evolution of Drosophila Germline Stem Cell and Neural Stem Cell Regulating Genes.

    PubMed

    Choi, Jae Young; Aquadro, Charles F

    2015-10-27

    Here, we study the molecular evolution of a near complete set of genes that had functional evidence in the regulation of the Drosophila germline and neural stem cell. Some of these genes have previously been shown to be rapidly evolving by positive selection raising the possibility that stem cell genes as a group have elevated signatures of positive selection. Using recent Drosophila comparative genome sequences and population genomic sequences of Drosophila melanogaster, we have investigated both long- and short-term evolution occurring across these two different stem cell systems, and compared them with a carefully chosen random set of genes to represent the background rate of evolution. Our results showed an excess of genes with evidence of a recent selective sweep in both germline and neural stem cells in D. melanogaster. However compared with their control genes, both stem cell systems had no significant excess of genes with long-term recurrent positive selection in D. melanogaster, or across orthologous sequences from the melanogaster group. The evidence of long-term positive selection was limited to a subset of genes with specific functions in both the germline and neural stem cell system.

  12. Nicotinamide metabolism regulates glioblastoma stem cell maintenance

    PubMed Central

    Jung, Jinkyu; Kim, Leo J.Y.; Wang, Xiuxing; Wu, Qiulian; Sanvoranart, Tanwarat; Hubert, Christopher G.; Prager, Briana C.; Wallace, Lisa C.; Jin, Xun; Mack, Stephen C.; Rich, Jeremy N.

    2017-01-01

    Metabolic dysregulation promotes cancer growth through not only energy production, but also epigenetic reprogramming. Here, we report that a critical node in methyl donor metabolism, nicotinamide N-methyltransferase (NNMT), ranked among the most consistently overexpressed metabolism genes in glioblastoma relative to normal brain. NNMT was preferentially expressed by mesenchymal glioblastoma stem cells (GSCs). NNMT depletes S-adenosyl methionine (SAM), a methyl donor generated from methionine. GSCs contained lower levels of methionine, SAM, and nicotinamide, but they contained higher levels of oxidized nicotinamide adenine dinucleotide (NAD+) than differentiated tumor cells. In concordance with the poor prognosis associated with DNA hypomethylation in glioblastoma, depletion of methionine, a key upstream methyl group donor, shifted tumors toward a mesenchymal phenotype and accelerated tumor growth. Targeting NNMT expression reduced cellular proliferation, self-renewal, and in vivo tumor growth of mesenchymal GSCs. Supporting a mechanistic link between NNMT and DNA methylation, targeting NNMT reduced methyl donor availability, methionine levels, and unmethylated cytosine, with increased levels of DNA methyltransferases, DNMT1 and DNMT3A. Supporting the clinical significance of these findings, NNMT portended poor prognosis for glioblastoma patients. Collectively, our findings support NNMT as a GSC-specific therapeutic target in glioblastoma by disrupting oncogenic DNA hypomethylation. PMID:28515364

  13. Auxin regulates distal stem cell differentiation in Arabidopsis roots.

    PubMed

    Ding, Zhaojun; Friml, Jirí

    2010-06-29

    The stem cell niche in the root meristem is critical for the development of the plant root system. The plant hormone auxin acts as a versatile trigger in many developmental processes, including the regulation of root growth, but its role in the control of the stem cell activity remains largely unclear. Here we show that local auxin levels, determined by biosynthesis and intercellular transport, mediate maintenance or differentiation of distal stem cells in the Arabidopsis thaliana roots. Genetic analysis shows that auxin acts upstream of the major regulators of the stem cell activity, the homeodomain transcription factor WOX5, and the AP-2 transcription factor PLETHORA. Auxin signaling for differentiation of distal stem cells requires the transcriptional repressor IAA17/AXR3 as well as the ARF10 and ARF16 auxin response factors. ARF10 and ARF16 activities repress the WOX5 transcription and restrict it to the quiescent center, where WOX5, in turn, is needed for the activity of PLETHORA. Our investigations reveal that long-distance auxin signals act upstream of the short-range network of transcriptional factors to mediate the differentiation of distal stem cells in roots.

  14. Mechanisms Regulating Stemness and Differentiation in Embryonal Carcinoma Cells

    PubMed Central

    2017-01-01

    Just over ten years have passed since the seminal Takahashi-Yamanaka paper, and while most attention nowadays is on induced, embryonic, and cancer stem cells, much of the pioneering work arose from studies with embryonal carcinoma cells (ECCs) derived from teratocarcinomas. This original work was broad in scope, but eventually led the way for us to focus on the components involved in the gene regulation of stemness and differentiation. As the name implies, ECCs are malignant in nature, yet maintain the ability to differentiate into the 3 germ layers and extraembryonic tissues, as well as behave normally when reintroduced into a healthy blastocyst. Retinoic acid signaling has been thoroughly interrogated in ECCs, especially in the F9 and P19 murine cell models, and while we have touched on this aspect, this review purposely highlights how some key transcription factors regulate pluripotency and cell stemness prior to this signaling. Another major focus is on the epigenetic regulation of ECCs and stem cells, and, towards that end, this review closes on what we see as a new frontier in combating aging and human disease, namely, how cellular metabolism shapes the epigenetic landscape and hence the pluripotency of all stem cells. PMID:28373885

  15. [Regulation of airway stem cell proliferation in idiopathic pulmonary fibrosis].

    PubMed

    Yang, S X; Wu, Q; Sun, X; Li, X; Li, K; Xu, L; Li, Y; Zhang, Q Y; Zhang, Y C; Chen, H Y

    2016-09-01

    To investigate the effect of fibroblasts on regulating airway stem cell proliferation in idiopathic pulmonary fibrosis. Lung cell suspension was prepared from β-actin-GFP mice. Airway stem cells were obtained by fluorescence activated cell sorting and co-cultured with lung fibroblasts. The fibroblasts were treated with TGF-β inhibitor SB43142. The expression of growth factors FGF1/2 and the effect of FGF1/2 on stem cell proliferation were observed. The cloning efficiency of airway stem cells, when co-cultured with normal lung fibroblast cells for 8 days, was (3.5±1.1)%, while the cloning efficiency was reduced to (0.04±0.04)% when co-cultured with lung fibroblasts from idiopathic pulmonary fibrosis patients. The difference between the 2 groups was statistically significant(P=0.002 5). TGF-β receptor inhibitor SB431542 increased lung fibroblast growth factors FGF1/2 expression.FGF1 mRNA expression was increased to the experimental group 0.005 5 from 0.000 2 in the control group.FGF2 mRNA expression of the amount raised to the experimental group 0.000 15 from 0.000 8 in the control group.FGF1/2 promoted the growth of airway stem cells. After FGF1/2 was co-cultured with normal lung fibroblast cells for 8 days, the cloning efficiency of airway stem cells was (0.3±0.1)%. During the development of idiopathic pulmonary fibrosis, fibroblast secreted FGF1/2 regulate airway stem cell proliferation.

  16. Regulation of spermatogonial stem cell compartment in the mouse testis.

    PubMed

    Iwamori, Naoki

    2014-01-01

    Spermatogenesis occurs throughout the adult lifetime of males and is supported by a robust stem cell system. Spermatogonial stem cells (SSCs) are the stem cells of postnatal male germ cells, and not only self-renew but also produce differentiated progeny continuously. Recent report revealed that differentiating spermatogonia could revert into an undifferentiated state, although it was believed that SSCs were homogeneous and that differentiating spermatogonia was not reversible. Although several molecules, which regulate SSC, have been identified so far, molecular mechanisms underlying the maintenance of SSCs as well as the reversible developmental lineage of SSCs remain to be elucidated. In this review, we describe a brief overview of spermatogenesis and summarize the molecular regulation of SSC compartment.

  17. The histone demethylase UTX regulates stem cell migration and hematopoiesis.

    PubMed

    Thieme, Sebastian; Gyárfás, Tobias; Richter, Cornelia; Özhan, Günes; Fu, Jun; Alexopoulou, Dimitra; Muders, Michael H; Michalk, Irene; Jakob, Christiane; Dahl, Andreas; Klink, Barbara; Bandola, Joanna; Bachmann, Michael; Schröck, Evelin; Buchholz, Frank; Stewart, A Francis; Weidinger, Gilbert; Anastassiadis, Konstantinos; Brenner, Sebastian

    2013-03-28

    Regulated migration of hematopoietic stem cells is fundamental for hematopoiesis. The molecular mechanisms underlying stem cell trafficking are poorly defined. Based on a short hairpin RNA library and stromal cell-derived factor-1 (SDF-1) migration screening assay, we identified the histone 3 lysine 27 demethylase UTX (Kdm6a) as a novel regulator for hematopoietic cell migration. Using hematopoietic stem and progenitor cells from our conditional UTX knockout (KO) mice, we were able to confirm the regulatory function of UTX on cell migration. Moreover, adult female conditional UTX KO mice displayed myelodysplasia and splenic erythropoiesis, whereas UTX KO males showed no phenotype. During development, all UTX KO female and a portion of UTX KO male embryos developed a cardiac defect, cranioschisis, and died in utero. Therefore, UTY, the male homolog of UTX, can compensate for UTX in adults and partially during development. Additionally, we found that UTX knockdown in zebrafish significantly impairs SDF-1/CXCR4-dependent migration of primordial germ cells. Our data suggest that UTX is a critical regulator for stem cell migration and hematopoiesis.

  18. A family business: stem cell progeny join the niche to regulate homeostasis

    PubMed Central

    Hsu, Ya-Chieh; Fuchs, Elaine

    2012-01-01

    Stem cell niches, the discrete microenvironments in which the stem cells reside, play a dominant part in regulating stem cell activity and behaviours. Recent studies suggest that committed stem cell progeny become indispensable components of the niche in a wide range of stem cell systems. These unexpected niche inhabitants provide versatile feedback signals to their stem cell parents. Together with other heterologous cell types that constitute the niche, they contribute to the dynamics of the microenvironment. As progeny are often located in close proximity to stem cell niches, similar feedback regulations may be the underlying principles shared by different stem cell systems. PMID:22266760

  19. A family business: stem cell progeny join the niche to regulate homeostasis.

    PubMed

    Hsu, Ya-Chieh; Fuchs, Elaine

    2012-01-23

    Stem cell niches, the discrete microenvironments in which the stem cells reside, play a dominant part in regulating stem cell activity and behaviours. Recent studies suggest that committed stem cell progeny become indispensable components of the niche in a wide range of stem cell systems. These unexpected niche inhabitants provide versatile feedback signals to their stem cell parents. Together with other heterologous cell types that constitute the niche, they contribute to the dynamics of the microenvironment. As progeny are often located in close proximity to stem cell niches, similar feedback regulations may be the underlying principles shared by different stem cell systems.

  20. A quantitative and dynamic model for plant stem cell regulation.

    PubMed

    Geier, Florian; Lohmann, Jan U; Gerstung, Moritz; Maier, Annette T; Timmer, Jens; Fleck, Christian

    2008-01-01

    Plants maintain pools of totipotent stem cells throughout their entire life. These stem cells are embedded within specialized tissues called meristems, which form the growing points of the organism. The shoot apical meristem of the reference plant Arabidopsis thaliana is subdivided into several distinct domains, which execute diverse biological functions, such as tissue organization, cell-proliferation and differentiation. The number of cells required for growth and organ formation changes over the course of a plants life, while the structure of the meristem remains remarkably constant. Thus, regulatory systems must be in place, which allow for an adaptation of cell proliferation within the shoot apical meristem, while maintaining the organization at the tissue level. To advance our understanding of this dynamic tissue behavior, we measured domain sizes as well as cell division rates of the shoot apical meristem under various environmental conditions, which cause adaptations in meristem size. Based on our results we developed a mathematical model to explain the observed changes by a cell pool size dependent regulation of cell proliferation and differentiation, which is able to correctly predict CLV3 and WUS over-expression phenotypes. While the model shows stem cell homeostasis under constant growth conditions, it predicts a variation in stem cell number under changing conditions. Consistent with our experimental data this behavior is correlated with variations in cell proliferation. Therefore, we investigate different signaling mechanisms, which could stabilize stem cell number despite variations in cell proliferation. Our results shed light onto the dynamic constraints of stem cell pool maintenance in the shoot apical meristem of Arabidopsis in different environmental conditions and developmental states.

  1. Retinoid signaling regulates breast cancer stem cell differentiation

    PubMed Central

    Ginestier, Christophe; Wicinski, Julien; Cervera, Nathalie; Monville, Florence; Finetti, Pascal; Bertucci, François; Wicha, Max S.; Birnbaum, Daniel; Charafe-Jauffret, Emmanuelle

    2010-01-01

    The cancer stem cell (CSC) hypothesis implicates the development of new therapeutic approaches to target the CSC population. Characterization of the pathways that regulate CSCs activity will facilitate the development of targeted therapies. We recently reported that the enzymatic activity of ALDH1, as measured by the ALDELFUOR assay, can be utilized to isolate normal and malignant breast stem cells in both primary tumors and cell lines. In this study, utilizing a tumorsphere assay, we have demonstrated the role of retinoid signaling in the regulation of breast CSCs self-renewal and differentiation. Utilizing the gene set enrichment analysis (GSEA) algorithm we identified gene sets and pathways associated with retinoid signaling. These pathways regulate breast CSCs biology and their inhibition may provide novel therapeutic approaches to target breast CSCs. PMID:19806016

  2. Laminin regulates PDGFRβ(+) cell stemness and muscle development.

    PubMed

    Yao, Yao; Norris, Erin H; Mason, Christopher E; Strickland, Sidney

    2016-05-03

    Muscle-resident PDGFRβ(+) cells, which include pericytes and PW1(+) interstitial cells (PICs), play a dual role in muscular dystrophy. They can either undergo myogenesis to promote muscle regeneration or differentiate into adipocytes and other cells to compromise regeneration. How the differentiation and fate determination of PDGFRβ(+) cells are regulated, however, remains unclear. Here, by utilizing a conditional knockout mouse line, we report that PDGFRβ(+) cell-derived laminin inhibits their proliferation and adipogenesis, but is indispensable for their myogenesis. In addition, we show that laminin alone is able to partially reverse the muscle dystrophic phenotype in these mice at the molecular, structural and functional levels. Further RNAseq analysis reveals that laminin regulates PDGFRβ(+) cell differentiation/fate determination via gpihbp1. These data support a critical role of laminin in the regulation of PDGFRβ(+) cell stemness, identify an innovative target for future drug development and may provide an effective treatment for muscular dystrophy.

  3. Laminin regulates PDGFRβ+ cell stemness and muscle development

    PubMed Central

    Yao, Yao; Norris, Erin H.; E. Mason, Christopher; Strickland, Sidney

    2016-01-01

    Muscle-resident PDGFRβ+ cells, which include pericytes and PW1+ interstitial cells (PICs), play a dual role in muscular dystrophy. They can either undergo myogenesis to promote muscle regeneration or differentiate into adipocytes and other cells to compromise regeneration. How the differentiation and fate determination of PDGFRβ+ cells are regulated, however, remains unclear. Here, by utilizing a conditional knockout mouse line, we report that PDGFRβ+ cell-derived laminin inhibits their proliferation and adipogenesis, but is indispensable for their myogenesis. In addition, we show that laminin alone is able to partially reverse the muscle dystrophic phenotype in these mice at the molecular, structural and functional levels. Further RNAseq analysis reveals that laminin regulates PDGFRβ+ cell differentiation/fate determination via gpihbp1. These data support a critical role of laminin in the regulation of PDGFRβ+ cell stemness, identify an innovative target for future drug development and may provide an effective treatment for muscular dystrophy. PMID:27138650

  4. Cell cycle regulation in human embryonic stem cells: links to adaptation to cell culture.

    PubMed

    Barta, Tomas; Dolezalova, Dasa; Holubcova, Zuzana; Hampl, Ales

    2013-03-01

    Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation. This review summarizes the current understanding of cell cycle regulation in hESCs. We discuss cell cycle properties as well as regulatory machinery governing cell cycle progression of undifferentiated hESCs. Additionally, we provide evidence that long-term culture of hESCs is accompanied by changes in cell cycle properties as well as configuration of several cell cycle regulatory molecules.

  5. 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.

  6. In situ mechanotransduction via vinculin regulates stem cell differentiation.

    PubMed

    Holle, Andrew W; Tang, Xinyi; Vijayraghavan, Deepthi; Vincent, Ludovic G; Fuhrmann, Alexander; Choi, Yu Suk; del Álamo, Juan C; Engler, Adam J

    2013-11-01

    Human mesenchymal stem cell (hMSC) proliferation, migration, and differentiation have all been linked to extracellular matrix stiffness, yet the signaling pathway(s) that are necessary for mechanotransduction remain unproven. Vinculin has been implicated as a mechanosensor in vitro, but here we demonstrate its ability to also regulate stem cell behavior, including hMSC differentiation. RNA interference-mediated vinculin knockdown significantly decreased stiffness-induced MyoD, a muscle transcription factor, but not Runx2, an osteoblast transcription factor, and impaired stiffness-mediated migration. A kinase binding accessibility screen predicted a cryptic MAPK1 signaling site in vinculin which could regulate these behaviors. Indeed, reintroduction of vinculin domains into knocked down cells indicated that MAPK1 binding site-containing vinculin constructs were necessary for hMSC expression of MyoD. Vinculin knockdown does not appear to interfere with focal adhesion assembly, significantly alter adhesive properties, or diminish cell traction force generation, indicating that its knockdown only adversely affected MAPK1 signaling. These data provide some of the first evidence that a force-sensitive adhesion protein can regulate stem cell fate. Copyright © AlphaMed Press.

  7. Adenomatous polyposis coli regulates Drosophila intestinal stem cell proliferation.

    PubMed

    Lee, Wen-Chih; Beebe, Katherine; Sudmeier, Lisa; Micchelli, Craig A

    2009-07-01

    Adult stem cells define a cellular reserve with the unique capacity to replenish differentiated cells of a tissue throughout an organism's lifetime. Previous analysis has demonstrated that the adult Drosophila midgut is maintained by a population of multipotent intestinal stem cells (ISCs) that resides in epithelial niches. Adenomatous polyposis coli (Apc), a tumor suppressor gene conserved in both invertebrates and vertebrates, is known to play a role in multiple developmental processes in Drosophila. Here, we examine the consequences of eliminating Apc function on adult midgut homeostasis. Our analysis shows that loss of Apc results in the disruption of midgut homeostasis and is associated with hyperplasia and multilayering of the midgut epithelium. A mosaic analysis of marked ISC cell lineages demonstrates that Apc is required specifically in ISCs to regulate proliferation, but is not required for ISC self-renewal or the specification of cell fate within the lineage. Cell autonomous activation of Wnt signaling in the ISC lineage phenocopied Apc loss and Apc mutants were suppressed in an allele-specific manner by abrogating Wnt signaling, suggesting that the effects of Apc are mediated in part by the Wnt pathway. Together, these data underscore the essential requirement of Apc in exerting regulatory control over stem cell activity, as well as the consequences that disrupting this regulation can have on tissue homeostasis.

  8. Somatic cell encystment promotes abscission in germline stem cells following a regulated block in cytokinesis.

    PubMed

    Lenhart, Kari F; DiNardo, Stephen

    2015-07-27

    In many tissues, the stem cell niche must coordinate behavior across multiple stem cell lineages. How this is achieved is largely unknown. We have identified delayed completion of cytokinesis in germline stem cells (GSCs) as a mechanism that regulates the production of stem cell daughters in the Drosophila testis. Through live imaging, we show that a secondary F-actin ring is formed through regulation of Cofilin activity to block cytokinesis progress after contractile ring disassembly. The duration of this block is controlled by Aurora B kinase. Additionally, we have identified a requirement for somatic cell encystment of the germline in promoting GSC abscission. We suggest that this non-autonomous role promotes coordination between stem cell lineages. These findings reveal the mechanisms by which cytokinesis is inhibited and reinitiated in GSCs and why such complex regulation exists within the stem cell niche.

  9. Epigenetic Gene Regulation in Stem Cells and Correlation to Cancer

    PubMed Central

    Mathews, Lesley A.; Crea, Francesco; Farrar, W. L.

    2009-01-01

    Through the classic study of genetics, much has been learned about the regulation and progression of human disease. Specifically, cancer has been defined as a disease driven by genetic alterations, including mutations in tumor-suppressor genes and oncogenes, as well as chromosomal abnormalities. However, the study of normal human development has identified that in addition to classical genetics, regulation of gene expression is also modified by ‘epigenetic’ alterations including chromatin remodeling and histone variants, DNA methylation, the regulation of polycomb group proteins and the epigenetic function of non-coding RNA. These changes are modifications inherited both during meiosis and mitosis, yet they do not result in alterations of the actual DNA sequence. A number of biological questions are directly influenced by epigenetics, such as how does a cell know when to divide, differentiate or remain quiescent, and more importantly, what happens when these pathways become altered? Do these alterations lead to the development and/or progression of cancer? This review will focus on summarizing the limited current literature involving epigenetic alterations in the context of human cancer stems cells (CSCs). The extent to which epigenetic changes define cell fate, identity, and phenotype are still under intense investigation, and many questions remain largely unanswered. Before discussing epigenetic gene silencing in CSCs, the different classifications of stem cells and their properties will be introduced. This will be followed by an introduction to the different epigenetic mechanisms Finally, there will be a discussion of the current knowledge of epigenetic modifications in stem cells, specifically what is known from rodent systems and established cancer cell lines, and how they are leading us to understand human stem cells. PMID:19443100

  10. Stem Cells

    MedlinePlus

    Stem cells are cells with the potential to develop into many different types of cells in the body. ... the body. There are two main types of stem cells: embryonic stem cells and adult stem cells. Stem ...

  11. Analysis of SOX2-Regulated Transcriptome in Glioma Stem Cells

    PubMed Central

    Acanda de la Rocha, Arlet M.; López-Bertoni, Hernando; Guruceaga, Elizabeth; González-Huarriz, Marisol; Martínez-Vélez, Naiara; Xipell, Enric; Fueyo, Juan; Gomez-Manzano, Candelaria

    2016-01-01

    Introduction Glioblastoma is the most malignant brain tumor in adults and is associated with poor survival despite multimodal treatments. Glioma stem-like cells (GSCs) are cells functionally defined by their self-renewal potential and the ability to reconstitute the original tumor upon orthotopic implantation. They have been postulated to be the culprit of glioma chemo- and radio-resistance ultimately leading to relapse. Understanding the molecular circuits governing the GSC compartment is essential. SOX2, a critical transcription regulator of embryonic and neural stem cell function, is deregulated in GSCs however; the precise molecular pathways regulated by this gene in GSCs remain poorly understood. Results We performed a genome-wide analysis of SOX2-regulated transcripts in GSCs, using a microarray. We identified a total of 2048 differentially expressed coding transcripts and 261 non-coding transcripts. Cell adhesion and cell-cell signaling are among the most enriched terms using Gene Ontology (GO) classification. The pathways altered after SOX2 down-modulation includes multiple cellular processes such as amino-acid metabolism and intercellular signaling cascades. We also defined and classified the set of non-coding transcripts differentially expressed regulated by SOX2 in GSCs, and validated two of them. Conclusions We present a comprehensive analysis of the transcriptome controlled by SOX2 in GSCs, gaining insights in the understanding of the potential roles of SOX2 in glioblastoma. PMID:27669421

  12. Natural and Synthetic Regulators of Embryonic Stem Cell Cardiogenesis

    PubMed Central

    Willems, Erik; Bushway, Paul J.

    2012-01-01

    Debilitating cardiomyocyte loss underlies the progression to heart failure. Although there have been significant advances in treatment, current therapies are intended to improve or preserve heart function rather than regenerate lost myocardium. A major hurdle in implementing a cell-based regenerative therapy is the inefficient differentiation of cardiomyocytes from either endogenous or exogenous stem cell sources. Moreover, cardiomyocytes that develop in human embryonic stem cell (hESC) or human-induced pluripotent stem cell (hIPSC) cultures are comparatively immature, even after prolonged culture, and differences in their calcium handling, ion channel, and force generation properties relative to adult cardiomyocytes raise concerns of improper integration and function after transplantation. Thus, the discovery of natural and novel small molecule synthetic regulators of differentiation and maturation would accelerate the development of stem-cell-based myocardial therapies. Here, we document recent advances in defining natural signaling pathways that direct the multistep cardiomyogenic differentiation program and the development of small molecules that might be used to enhance differentiation as well as the potential characteristics of lead candidates for pharmaceutical stimulation of endogenous myocardial replacement. PMID:19319460

  13. Adipose stem cells: biology, safety, regulation, and regenerative potential.

    PubMed

    Minteer, Danielle M; Marra, Kacey G; Rubin, J Peter

    2015-04-01

    This article discusses adipose-derived stem cell (ASC) biology, describes the current knowledge in the literature for the safety and regulation of ASCs, and provides a brief overview of the regenerative potential of ASCs. It is not an exhaustive listing of all available clinical studies or every study applying ASCs in tissue engineering and regenerative medicine, but is an objective commentary of these topics.

  14. FHL2 regulates hematopoietic stem cell functions under stress conditions

    PubMed Central

    Hou, Yu; Wang, Xiaoqin; Li, LiPing; Fan, Rong; Chen, Ju; Zhu, Tongyu; Li, Wen; Jiang, Yanwen; Mittal, Nupur; Wu, Wenshu; Peace, David; Qian, Zhijian

    2014-01-01

    FHL2, a member of the four and one half LIM domain protein family, is a critical transcriptional modulator. Here, we identify FHL2 as a critical regulator of hematopoietic stem cells (HSCs) that is essential for maintaining HSC self-renewal under regenerative stress. We find that Fhl2 loss has limited effects on hematopoiesis under homeostatic conditions. In contrast, Fhl2-null chimeric mice reconstituted with Fhl2-null bone marrow cells developed abnormal hematopoiesis with significantly reduced numbers of HSCs, hematopoietic progenitor cells (HPCs), red blood cells and platelets as well as hemoglobin levels. In addition, HSCs displayed a significantly reduced self-renewal capacity and were skewed toward myeloid lineage differentiation. We find that Fhl2 loss reduces both HSC quiescence and survival in response to regenerative stress, probably as a consequence of Fhl2-loss-mediated down-regulation of cyclin dependent kinase (CDK)-inhibitors, including p21(Cip) and p27(Kip1). Interestingly, FHL2 is regulated under control of a tissue specific promoter in hematopoietic cells and it is down-regulated by DNA hypermethylation in the leukemia cell line and primary leukemia cells. Furthermore, we find that down-regulation of FHL2 frequently occurs in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) patients, raising a possibility that FHL2 down-regulation plays a role in the pathogenesis of myeloid malignancies. PMID:25179730

  15. Regulations and guidelines governing stem cell based products: Clinical considerations

    PubMed Central

    George, Bobby

    2011-01-01

    The use of stem cells as medicines is a promising and upcoming area of research as they may be able to help the body to regenerate damaged or lost tissue in a host of diseases like Parkinson′s, multiple sclerosis, heart disease, liver disease, spinal cord damage, cancer and many more. Translating basic stem cell research into routine therapies is a complex multi-step process which entails the challenge related to managing the expected therapeutic benefits with the potential risks while complying with the existing regulations and guidelines. While in the United States (US) and European Union (EU) regulations are in place, in India, we do not have a well-defined regulatory framework for “stem cell based products (SCBP)”. There are several areas that need to be addressed as it is quite different from that of pharmaceuticals. These range from establishing batch consistency, product stability to product safety and efficacy through pre-clinical, clinical studies and marketing authorization. This review summarizes the existing regulations/guidelines in US, EU, India, and the associated challenges in developing SCBP with emphasis on clinical aspects. PMID:21897884

  16. Prostaglandin E2 regulates vertebrate haematopoietic stem cell homeostasis

    PubMed Central

    North, Trista E.; Goessling, Wolfram; Walkley, Carl R.; Lengerke, Claudia; Kopani, Kamden R.; Lord, Allegra M.; Weber, Gerhard J.; Bowman, Teresa V.; Jang, Il-Ho; Grosser, Tilo; FitzGerald, Garret A.; Daley, George Q.; Orkin, Stuart H.; Zon, Leonard I.

    2009-01-01

    Haematopoietic stem cell (HSC) homeostasis is tightly controlled by growth factors, signalling molecules and transcription factors. Definitive HSCs derived during embryogenesis in the aorta-gonad-mesonephros region subsequently colonize fetal and adult haematopoietic organs1,2. To identify new modulators of HSC formation and homeostasis, a panel of biologically active compounds was screened for effects on stem cell induction in the zebrafish aorta-gonad-mesonephros region. Here, we show that chemicals that enhance prostaglandin (PG) E2 synthesis increased HSC numbers, and those that block prostaglandin synthesis decreased stem cell numbers. The cyclooxygenases responsible for PGE2 synthesis were required for HSC formation. A stable derivative of PGE2 improved kidney marrow recovery following irradiation injury in the adult zebrafish. In murine embryonic stem cell differentiation assays, PGE2 caused amplification of multipotent progenitors. Furthermore, ex vivo exposure to stabilized PGE2 enhanced spleen colony forming units at day 12 post transplant and increased the frequency of long-term repopulating HSCs present in murine bone marrow after limiting dilution competitive transplantation. The conserved role for PGE2 in the regulation of vertebrate HSC homeostasis indicates that modulation of the prostaglandin pathway may facilitate expansion of HSC number for therapeutic purposes. PMID:17581586

  17. Regulation of skeletal muscle stem cells by fibroblast growth factors.

    PubMed

    Pawlikowski, Bradley; Vogler, Thomas Orion; Gadek, Katherine; Olwin, Bradley B

    2017-03-01

    Fibroblast growth factors (FGFs) are essential for self-renewal of skeletal muscle stem cells (satellite cells) and required for maintenance and repair of skeletal muscle. Satellite cells express high levels of FGF receptors 1 and 4, low levels of FGF receptor 3, and little or no detectable FGF receptor 2. Of the multiple FGFs that influence satellite cell function in culture, FGF2 and FGF6 are the only members that regulate satellite cell function in vivo by activating ERK MAPK, p38α/β MAPKs, PI3 kinase, PLCγ and STATs. Regulation of FGF signaling is complex in satellite cells, requiring Syndecan-4, a heparan sulfate proteoglycan, as well as ß1-integrin and fibronectin. During aging, reduced responsiveness to FGF diminishes satellite cell self-renewal, leading to impaired skeletal muscle regeneration and depletion of satellite cells. Mislocalization of ß1-integrin, reductions in fibronectin, and alterations in heparan sulfate content all contribute to reduced FGF responsiveness in satellite cells. How these cell surface proteins regulate satellite cell self-renewal is incompletely understood. Here we summarize the current knowledge, highlighting the role(s) for FGF signaling in skeletal muscle regeneration, satellite cell behavior, and age-induced muscle wasting. Developmental Dynamics, 2017. © 2017 Wiley Periodicals, Inc.

  18. The challenges of regulating stem cell-based products.

    PubMed

    von Tigerstrom, Barbara J

    2008-12-01

    Appropriate regulation of stem cell-based products is essential to ensure public safety and trust while minimising unnecessary barriers to product development, but presents numerous challenges. Weaknesses of existing legal frameworks include variation between jurisdictions and poor fit between product categories and new technologies. The new European Regulation on advanced therapy medicinal products is an important attempt to provide a consolidated regulatory framework for novel products. Others can learn from issues encountered in its development, including definition of product categories, ethical concerns, and the application of regulations to small-scale production. Several aspects of the Regulation will be useful models, but some larger questions remain unresolved. As reform efforts move forward, harmonisation and sharing of expertise will be vital to effective regulation.

  19. Implications of Stem Cell Growth Regulation for Breast Cancer

    DTIC Science & Technology

    2007-06-01

    with stem/progenitor cells, and find that LRP5-high cells co-purify with the MRU stem cell-enriched fraction (Fig.1C, D). These LRP5-high cells...stem cells that grow in vivo ( MRU ) and double negative (DN). The MRU fraction is highly enriched in LRP5-high cells. A distinct population that...vivo (mammary repopulating units, MRUs , Fig. 5). Mammary progenitor cells are defined as having insignificant growth potential in vivo, but

  20. Pleiotrophin regulates the expansion and regeneration of hematopoietic stem cells

    PubMed Central

    Himburg, Heather A; Muramoto, Garrett G; Daher, Pamela; Meadows, Sarah K; Russell, J Lauren; Doan, Phuong; Chi, Jen-Tsan; Salter, Alice B; Lento, William E; Reya, Tannishtha; Chao, Nelson; Chute, John P

    2013-01-01

    Hematopoietic stem cell (HSC) self-renewal is regulated by both intrinsic and extrinsic signals. Although some of the pathways that regulate HSC self-renewal have been uncovered, it remains largely unknown whether these pathways can be triggered by deliverable growth factors to induce HSC growth or regeneration. Here we show that pleiotrophin, a neurite outgrowth factor with no known function in hematopoiesis, efficiently promotes HSC expansion in vitro and HSC regeneration in vivo. Treatment of mouse bone marrow HSCs with pleiotrophin caused a marked increase in long-term repopulating HSC counts in culture, as measured in competitive repopulating assays. Treatment of human cord blood CD34+CDCD38−Lin− cells with pleiotrophin also substantially increased severe combined immunodeficient (SCID)-repopulating cell counts in culture, compared to input and cytokine-treated cultures. Systemic administration of pleiotrophin to irradiated mice caused a pronounced expansion of bone marrow stem and progenitor cells in vivo, indicating that pleiotrophin is a regenerative growth factor for HSCs. Mechanistically, pleiotrophin activated phosphoinositide 3-kinase (PI3K) signaling in HSCs; antagonism of PI3K or Notch signaling inhibited pleiotrophin-mediated expansion of HSCs in culture. We identify the secreted growth factor pleiotrophin as a new regulator of both HSC expansion and regeneration PMID:20305662

  1. Pleiotrophin regulates the expansion and regeneration of hematopoietic stem cells.

    PubMed

    Himburg, Heather A; Muramoto, Garrett G; Daher, Pamela; Meadows, Sarah K; Russell, J Lauren; Doan, Phuong; Chi, Jen-Tsan; Salter, Alice B; Lento, William E; Reya, Tannishtha; Chao, Nelson J; Chute, John P

    2010-04-01

    Hematopoietic stem cell (HSC) self-renewal is regulated by both intrinsic and extrinsic signals. Although some of the pathways that regulate HSC self-renewal have been uncovered, it remains largely unknown whether these pathways can be triggered by deliverable growth factors to induce HSC growth or regeneration. Here we show that pleiotrophin, a neurite outgrowth factor with no known function in hematopoiesis, efficiently promotes HSC expansion in vitro and HSC regeneration in vivo. Treatment of mouse bone marrow HSCs with pleiotrophin caused a marked increase in long-term repopulating HSC numbers in culture, as measured in competitive repopulating assays. Treatment of human cord blood CD34(+)CDCD38(-)Lin(-) cells with pleiotrophin also substantially increased severe combined immunodeficient (SCID)-repopulating cell counts in culture, compared to input and cytokine-treated cultures. Systemic administration of pleiotrophin to irradiated mice caused a pronounced expansion of bone marrow stem and progenitor cells in vivo, indicating that pleiotrophin is a regenerative growth factor for HSCs. Mechanistically, pleiotrophin activated phosphoinositide 3-kinase (PI3K) signaling in HSCs; antagonism of PI3K or Notch signaling inhibited pleiotrophin-mediated expansion of HSCs in culture. We identify the secreted growth factor pleiotrophin as a new regulator of both HSC expansion and regeneration.

  2. Microenvironmental Regulation of Telomerase Isoforms in Human Embryonic Stem Cells

    PubMed Central

    Radan, Lida; Hughes, Chris S.; Teichroeb, Jonathan H.; Zamora, Flora M. Vieira; Jewer, Michael; Postovit, Lynne-Marie

    2014-01-01

    Recent evidence points to extra-telomeric, noncanonical roles for telomerase in regulating stem cell function. In this study, human embryonic stem cells (hESCs) were cultured in 20% or 2% O2 microenvironments for up to 5 days and evaluated for telomerase reverse transcriptase (TERT) expression and telomerase activity. Results showed increased cell survival and maintenance of the undifferentiated state with elevated levels of nuclear TERT in 2% O2-cultured hESCs despite no significant difference in telomerase activity compared with their high-O2-cultured counterparts. Pharmacological inhibition of telomerase activity using a synthetic tea catechin resulted in spontaneous hESC differentiation, while telomerase inhibition with a phosphorothioate oligonucleotide telomere mimic did not. Reverse transcription polymerase chain reaction (RT-PCR) analysis revealed variations in transcript levels of full-length and alternate splice variants of TERT in hESCs cultured under varying O2 atmospheres. Steric-blocking of Δα and Δβ hTERT splicing using morpholino oligonucleotides altered the hTERT splicing pattern and rapidly induced spontaneous hESC differentiation that appeared biased toward endomesodermal and neuroectodermal cell fates, respectively. Together, these results suggest that post-transcriptional regulation of TERT under varying O2 microenvironments may help regulate hESC survival, self-renewal, and differentiation capabilities through expression of extra-telomeric telomerase isoforms. PMID:24749509

  3. [Bone and Stem Cells. Immune cell regulation by the bone marrow niche].

    PubMed

    Terashima, Asuka; Takayanagi, Hiroshi

    2014-04-01

    Adult hematopoietic stem cells (HSCs) are maintained in the bone marrow and give rise to all blood cell types. The maintenance and the differentiation of blood cells including immune cells are essential for host defense and oxygen delivery. HSCs are maintained in microenvironments called stem cell niches, which consists of various cell types in bone marrow. Recently, new visualization technologies and assay systems brought advances in studies on the stem cell niche. In addition, several reports demonstrated that osteoblasts and osteocytes regulate not only HSC homeostasis but also immune cell differentiation, suggesting a close relationship between bone cells and HSCs.

  4. SHIP1-expressing mesenchymal stem cells regulate hematopoietic stem cell homeostasis and lineage commitment during aging.

    PubMed

    Iyer, Sonia; Brooks, Robert; Gumbleton, Matthew; Kerr, William G

    2015-05-01

    Hematopoietic stem cell (HSC) self-renewal and lineage choice are subject to intrinsic control. However, this intrinsic regulation is also impacted by external cues provided by niche cells. There are multiple cellular components that participate in HSC support with the mesenchymal stem cell (MSC) playing a pivotal role. We had previously identified a role for SH2 domain-containing inositol 5'-phosphatase-1 (SHIP1) in HSC niche function through analysis of mice with germline or induced SHIP1 deficiency. In this study, we show that the HSC compartment expands significantly when aged in a niche that contains SHIP1-deficient MSC; however, this expanded HSC compartment exhibits a strong bias toward myeloid differentiation. In addition, we show that SHIP1 prevents chronic G-CSF production by the aging MSC compartment. These findings demonstrate that intracellular signaling by SHIP1 in MSC is critical for the control of HSC output and lineage commitment during aging. These studies increase our understanding of how myeloid bias occurs in aging and thus could have implications for the development of myeloproliferative disease in aging.

  5. Cellular interactions regulate stem cell differentiation in tri-culture.

    PubMed

    Wang, I-Ning E; Bogdanowicz, Danielle R; Mitroo, Siddarth; Shan, Jing; Kala, Sonam; Lu, Helen H

    2016-11-01

    Currently, the mechanism governing the regeneration of the soft tissue-to-bone interface, such as the transition between the anterior cruciate ligament (ACL) and bone, is not known. Focusing on the ACL-to-bone insertion, this study tests the novel hypothesis that interactions between cells from the ligament (fibroblasts) and bone (osteoblasts) initiate interface regeneration. Specifically, these heterotypic cell interactions direct the fibrochondrogenic differentiation of interface-relevant cell populations, defined here as ligament fibroblasts and bone marrow stromal cells (BMSC). The objective of this study is to examine the effects of heterotypic cellular interactions on BMSC or fibroblast growth and biosynthesis, as well as expression of fibrocartilage-relevant markers in tri-culture. The effects of cell-cell physical contact and paracrine interactions between fibroblasts and osteoblasts were also determined. It was found that, in tri-culture with fibroblasts and osteoblasts, BMSC exhibited greater fibrochondrogenic potential than ligament fibroblasts. The growth of BMSC decreased while proteoglycan production and TGF-β3 expression increased. Moreover, tri-culture regulated BMSC response via paracrine factors, and interestingly, fibroblast-osteoblast contact further promoted proteoglycan and TGF-β1 synthesis as well as induced SOX9 expression in BMSC. Collectively, the findings of this study suggest that fibroblast-osteoblast interactions play an important role in regulating the stem cell niche for fibrocartilage regeneration, and the mechanisms of these interactions are directed by paracrine factors and augmented with direct cell-cell contact.

  6. Cell-cycle regulation in embryonic stem cells: centrosomal decisions on self-renewal.

    PubMed

    Koledova, Zuzana; Krämer, Alwin; Kafkova, Leona Raskova; Divoky, Vladimir

    2010-11-01

    Embryonic stem cells seem to have the intriguing capacity to divide indefinitely while retaining their pluripotency. This self-renewal is accomplished by specialized mechanisms of cell-cycle control. In the last few years, several studies have provided evidence for a direct link between cell-cycle regulation and cell-fate decisions in stem cells. In this review, we discuss the peculiarities of embryonic stem cell-cycle control mechanisms, implicate their involvement in cell-fate decisions, and distinguish centrosomes as important players in the self-renewal versus differentiation roulette.

  7. DNA asymmetry and cell fate regulation in stem cells.

    PubMed

    Yennek, Siham; Tajbakhsh, Shahragim

    2013-01-01

    The semi-conservative nature of DNA replication has suggested that identical DNA molecules within chromatids are inherited by daughter cells after cell division. Numerous reports of non-random DNA segregation in prokaryotes and eukaryotes suggest that this is not always the case, and that epigenetic marks on chromatids, if not the individual DNA strands themselves, could have distinct signatures. Their selective distribution to daughter cells provides a novel mechanism for gene and cell fate regulation by segregating chromatids asymmetrically. Here we highlight some examples and potential mechanisms that can regulate this process. We propose that cellular asymmetry is inherently present during each cell division, and that it provides an opportunity during each cell cycle for moderating cell fates.

  8. Epigenetic mechanisms regulating differentiation of neural stem/precursor cells.

    PubMed

    Adefuin, Aliya Mari D; Kimura, Ayaka; Noguchi, Hirofumi; Nakashima, Kinichi; Namihira, Masakazu

    2014-01-01

    Differentiation of neural stem/precursor cells (NS/PCs) into neurons, astrocytes and oligodendrocytes during mammalian brain development is a carefully controlled and timed event. Increasing evidences suggest that epigenetic regulation is necessary to drive this. Here, we provide an overview of the epigenetic mechanisms involved in the developing mammalian embryonic forebrain. Histone methylation is a key factor but other epigenetic factors such as DNA methylation and noncoding RNAs also partake during fate determination. As numerous epigenetic modifications have been identified, future studies on timing and regional specificity of these modifications will further deepen our understanding of how intrinsic and extrinsic mechanisms participate together to precisely control brain development.

  9. Surface topography during neural stem cell differentiation regulates cell migration and cell morphology.

    PubMed

    Czeisler, Catherine; Short, Aaron; Nelson, Tyler; Gygli, Patrick; Ortiz, Cristina; Catacutan, Fay Patsy; Stocker, Ben; Cronin, James; Lannutti, John; Winter, Jessica; Otero, José Javier

    2016-12-01

    We sought to determine the contribution of scaffold topography to the migration and morphology of neural stem cells by mimicking anatomical features of scaffolds found in vivo. We mimicked two types of central nervous system scaffolds encountered by neural stem cells during development in vitro by constructing different diameter electrospun polycaprolactone (PCL) fiber mats, a substrate that we have shown to be topographically similar to brain scaffolds. We compared the effects of large fibers (made to mimic blood vessel topography) with those of small-diameter fibers (made to mimic radial glial process topography) on the migration and differentiation of neural stem cells. Neural stem cells showed differential migratory and morphological reactions with laminin in different topographical contexts. We demonstrate, for the first time, that neural stem cell biological responses to laminin are dependent on topographical context. Large-fiber topography without laminin prevented cell migration, which was partially reversed by treatment with rock inhibitor. Cell morphology complexity assayed by fractal dimension was inhibited in nocodazole- and cytochalasin-D-treated neural precursor cells in large-fiber topography, but was not changed in small-fiber topography with these inhibitors. These data indicate that cell morphology has different requirements on cytoskeletal proteins dependent on the topographical environment encountered by the cell. We propose that the physical structure of distinct scaffolds induces unique signaling cascades that regulate migration and morphology in embryonic neural precursor cells. J. Comp. Neurol. 524:3485-3502, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Arginine Methylation by PRMT1 Regulates Muscle Stem Cell Fate.

    PubMed

    Blanc, Roméo Sébastien; Vogel, Gillian; Li, Xing; Yu, Zhenbao; Li, Shawn; Richard, Stéphane

    2017-02-01

    Quiescent muscle stem cells (MSCs) become activated in response to skeletal muscle injury to initiate regeneration. Activated MSCs proliferate and differentiate to repair damaged fibers or self-renew to maintain the pool and ensure future regeneration. The balance between self-renewal, proliferation, and differentiation is a tightly regulated process controlled by a genetic cascade involving determinant transcription factors such as Pax7, Myf5, MyoD, and MyoG. Recently, there have been several reports about the role of arginine methylation as a requirement for epigenetically mediated control of muscle regeneration. Here we report that the protein arginine methyltransferase 1 (PRMT1) is expressed in MSCs and that conditional ablation of PRMT1 in MSCs using Pax7(CreERT2) causes impairment of muscle regeneration. Importantly, PRMT1-deficient MSCs have enhanced cell proliferation after injury but are unable to terminate the myogenic differentiation program, leading to regeneration failure. We identify the coactivator of Six1, Eya1, as a substrate of PRMT1. We show that PRMT1 methylates Eya1 in vitro and that loss of PRMT1 function in vivo prevents Eya1 methylation. Moreover, we observe that PRMT1-deficient MSCs have reduced expression of Eya1/Six1 target MyoD due to disruption of Eya1 recruitment at the MyoD promoter and subsequent Eya1-mediated coactivation. These findings suggest that arginine methylation by PRMT1 regulates muscle stem cell fate through the Eya1/Six1/MyoD axis.

  11. Cell cycle regulation of embryonic stem cells and mouse embryonic fibroblasts lacking functional Pax7.

    PubMed

    Czerwinska, Areta M; Nowacka, Joanna; Aszer, Magdalena; Gawrzak, Sylwia; Archacka, Karolina; Fogtman, Anna; Iwanicka-Nowicka, Roksana; Jańczyk-Ilach, Katarzyna; Koblowska, Marta; Ciemerych, Maria A; Grabowska, Iwona

    2016-11-01

    The transcription factor Pax7 plays a key role during embryonic myogenesis and in adult organisms in that it sustains the proper function of satellite cells, which serve as adult skeletal muscle stem cells. Recently we have shown that lack of Pax7 does not prevent the myogenic differentiation of pluripotent stem cells. In the current work we show that the absence of functional Pax7 in differentiating embryonic stem cells modulates cell cycle facilitating their proliferation. Surprisingly, deregulation of Pax7 function also positively impacts at the proliferation of mouse embryonic fibroblasts. Such phenotypes seem to be executed by modulating the expression of positive cell cycle regulators, such as cyclin E.

  12. Mechanics regulates fate decisions of human embryonic stem cells.

    PubMed

    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.

  13. 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

  14. Nutritional regulation of stem and progenitor cells in Drosophila

    PubMed Central

    Shim, Jiwon; Gururaja-Rao, Shubha; Banerjee, Utpal

    2013-01-01

    Stem cells and their progenitors are maintained within a microenvironment, termed the niche, through local cell-cell communication. Systemic signals originating outside the niche also affect stem cell and progenitor behavior. This review summarizes studies that pertain to nutritional effects on stem and progenitor cell maintenance and proliferation in Drosophila. Multiple tissue types are discussed that utilize the insulin-related signaling pathway to convey nutritional information either directly to these progenitors or via other cell types within the niche. The concept of systemic control of these cell types is not limited to Drosophila and may be functional in vertebrate systems, including mammals. PMID:24255094

  15. microRNA regulation of human pancreatic cancer stem cells

    PubMed Central

    Xu, Yi-Fan; Hannafon, Bethany N.

    2017-01-01

    microRNAs (miRNAs) are a group of small non-coding RNAs that function primarily in the post transcriptional regulation of gene expression in plants and animals. Deregulation of miRNA expression in cancer cells, including pancreatic cancer cells, is well documented, and the involvement of miRNAs in orchestrating tumor genesis and cancer progression has been recognized. This review focuses on recent reports demonstrating that miRNAs are involved in regulation of pancreatic cancer stem cells (CSCs). A number of miRNA species have been identified to be involved in regulating pancreatic CSCs, including miR-21, miR-34, miR-1246, miR-221, the miR-17-92 cluster, the miR-200 and let-7 families. Furthermore, the Notch-signaling pathway and epithelial-mesenchymal transition (EMT) process are associated with miRNA regulation of pancreatic CSCs. Given the significant contribution of CSCs to chemo-resistance and tumor progression, a better understanding of how miRNAs function in pancreatic CSCs could provide novel strategies for the development of therapeutics and diagnostics for this devastating disease. PMID:28217707

  16. Alternative splicing regulates pluripotent state in pluripotent stem cells.

    PubMed

    He, Ling; Bai, Qiang; Tang, Liling

    2015-01-01

    Alternative splicing (AS) generates multiple mature mRNAs from a single pre-mRNA, so AS is the main contributor for the diversity of the proteins, participating in most of the cellular processes. For pluripotent stem cells (PSCs), great effort has been made to search for pluripotency-related genes and their regulatory mechanisms. However, the sophisticated regulation still remains to be clear. Recent studies indicate that stem cells undergo a unique AS pattern and have a different protein expression profile from differentiated cells, giving a new clue that AS switching or AS itself may play a significant role in the processes of differentiation and somatic reprogramming. Indeed, accumulating evidences prove that AS plays critical roles in maintaining pluripotent homeostasis in PSCs. In this review, we summarized recent researches on AS in ESCs and iPSCs, including some distinct AS events in pluripotent cells, and then discussed the new progress on mechanisms for AS in ESCs and iPSCs differentiation and somatic reprogramming.

  17. Isolation, characterization, and molecular regulation of muscle stem cells

    PubMed Central

    Fukada, So-ichiro; Ma, Yuran; Ohtani, Takuji; Watanabe, Yoko; Murakami, Satoshi; Yamaguchi, Masahiko

    2013-01-01

    Skeletal muscle has great regenerative capacity which is dependent on muscle stem cells, also known as satellite cells. A loss of satellite cells and/or their function impairs skeletal muscle regeneration and leads to a loss of skeletal muscle power; therefore, the molecular mechanisms for maintaining satellite cells in a quiescent and undifferentiated state are of great interest in skeletal muscle biology. Many studies have demonstrated proteins expressed by satellite cells, including Pax7, M-cadherin, Cxcr4, syndecan3/4, and c-met. To further characterize satellite cells, we established a method to directly isolate satellite cells using a monoclonal antibody, SM/C-2.6. Using SM/C-2.6 and microarrays, we measured the genes expressed in quiescent satellite cells and demonstrated that Hesr3 may complement Hesr1 in generating quiescent satellite cells. Although Hesr1- or Hesr3-single knockout mice show a normal skeletal muscle phenotype, including satellite cells, Hesr1/Hesr3-double knockout mice show a gradual decrease in the number of satellite cells and increase in regenerative defects dependent on satellite cell numbers. We also observed that a mouse's genetic background affects the regenerative capacity of its skeletal muscle and have established a line of DBA/2-background mdx mice that has a much more severe phenotype than the frequently used C57BL/10-mdx mice. The phenotype of DBA/2-mdx mice also seems to depend on the function of satellite cells. In this review, we summarize the methodology of direct isolation, characterization, and molecular regulation of satellite cells based on our results. The relationship between the regenerative capacity of satellite cells and progression of muscular disorders is also summarized. In the last part, we discuss application of the accumulating scientific information on satellite cells to treatment of patients with muscular disorders. PMID:24273513

  18. 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

  19. Metabolic Regulation of Stem Cell Behavior and Implications for Aging

    PubMed Central

    Jasper, Heinrich; Jones, D. Leanne

    2010-01-01

    Caloric intake influences metabolic homeostasis, somatic maintenance, tissue regeneration, and longevity in metazoans. Recent studies indicate that nutrient-dependent changes in stem cell populations play an important role in these effects. Here, we review the emerging picture of how nutrient-sensing pathways affect stem cell behavior, providing a mechanism to influence life span. PMID:21109189

  20. Regulated GDNF Delivery in Vivo Using Neural Stem Cells

    DTIC Science & Technology

    2007-04-01

    other neurodegenerative models including amyotrophic lateral sclerosis (ALS) and stroke (Kaspar et al., 2003; Cao et al., 2003; Guan et al., 2001...learning more about stem cell drug delivery it may be possible to explore other therapies for war injuries in the future. References Bilak...Neural Stem Cells PRINCIPAL INVESTIGATOR: Clive Svendsen CONTRACTING ORGANIZATION: University of Wisconsin-Madison

  1. Interferon gamma Signaling Positively Regulates Hematopoietic Stem Cell Emergence

    PubMed Central

    Sawamiphak, Suphansa; Kontarakis, Zacharias; Stainier, Didier Y.R.

    2014-01-01

    Summary Vertebrate hematopoietic stem cells (HSCs) emerge in the aorta-gonad-mesonephros (AGM) region from “hemogenic” endothelium. Here we show that the pro-inflammatory cytokine Ifn-γ and its receptor Crfb17 positively regulate HSC development in zebrafish. This regulation does not appear to modulate the proliferation or survival of HSCs or endothelial cells, but rather the endothelial to HSC transition. Notch signaling and blood flow positively regulate the expression of ifng and crfb17 in the AGM. Notably, Ifn-γ overexpression partially rescues the HSC loss observed in the absence of blood flow or Notch signaling. Importantly, Ifn-γ signaling acts cell-autonomously to control the endothelial to HSC transition. Ifn-γ activates Stat3, an atypical transducer of Ifn-γ signaling, in the AGM, and Stat3 inhibition decreases HSC formation. Together, our findings uncover a developmental role for an inflammatory cytokine and place its action downstream of Notch signaling and blood flow to control Stat3 activation and HSC emergence. PMID:25490269

  2. Classification of Hydrogels Based on Their Source: A Review and Application in Stem Cell Regulation

    NASA Astrophysics Data System (ADS)

    Khansari, Maziyar M.; Sorokina, Lioudmila V.; Mukherjee, Prithviraj; Mukhtar, Farrukh; Shirdar, Mostafa Rezazadeh; Shahidi, Mahnaz; Shokuhfar, Tolou

    2017-08-01

    Stem cells are recognized by their self-renewal ability and can give rise to specialized progeny. Hydrogels are an established class of biomaterials with the ability to control stem cell fate via mechanotransduction. They can mimic various physiological conditions to influence the fate of stem cells and are an ideal platform to support stem cell regulation. This review article provides a summary of recent advances in the application of different classes of hydrogels based on their source (e.g., natural, synthetic, or hybrid). This classification is important because the chemistry of substrate affects stem cell differentiation and proliferation. Natural and synthetic hydrogels have been widely used in stem cell regulation. Nevertheless, they have limitations that necessitate a new class of material. Hybrid hydrogels obtained by manipulation of the natural and synthetic ones can potentially overcome these limitations and shape the future of research in application of hydrogels in stem cell regulation.

  3. Regulation of apoptosis pathways in cancer stem cells.

    PubMed

    Fulda, Simone

    2013-09-10

    Cancer stem cell are considered to represent a population within the bulk tumor that share many similarities to normal stem cells as far as their capacities to self-renew, differentiate, proliferate and to reconstitute the entire tumor upon serial transplantation are concerned. Since cancer stem cells have been shown to be critical for maintaining tumor growth and have been implicated in treatment resistance and tumor progression, they constitute relevant targets for therapeutic intervention. Indeed, it has been postulated that eradication of cancer stem cells will be pivotal in order to achieve long-term relapse-free survival. However, one of the hallmarks of cancer stem cells is their high resistance to undergo cell death including apoptosis in response to environmental cues or cytotoxic stimuli. Since activation of apoptosis programs in tumor cells underlies the antitumor activity of most currently used cancer therapeutics, it will be critical to develop strategies to overcome the intrinsic resistance to apoptosis of cancer stem cells. Thus, a better understanding of the molecular mechanisms that are responsible for the ability of cancer stem cells to evade apoptosis will likely open new avenues to target this critical pool of cells within the tumor in order to develop more efficient treatment options for patients suffering from cancer.

  4. Wnt pathway regulation of embryonic stem cell self-renewal.

    PubMed

    Merrill, Bradley J

    2012-09-01

    Embryonic stem cells (ESCs) can generate all of the cell types found in the adult organism. Remarkably, they retain this ability even after many cell divisions in vitro, as long as the culture conditions prevent differentiation of the cells. Wnt signaling and β-catenin have been shown to cause strong effects on ESCs both in terms of stimulating the expansion of stem cells and stimulating differentiation toward lineage committed cell types. The varied effects of Wnt signaling in ESCs, alongside the sometimes unconventional mechanisms underlying the effects, have generated a fair amount of controversy and intrigue regarding the role of Wnt signaling in pluripotent stem cells. Insights into the mechanisms of Wnt function in stem cells can be gained by examination of the causes for seemingly opposing effects of Wnt signaling on self-renewal versus differentiation.

  5. Epac Activation Regulates Human Mesenchymal Stem Cells Migration and Adhesion.

    PubMed

    Yu, Jiao-Le; Deng, Ruixia; Chung, Sookja K; Chan, Godfrey Chi-Fung

    2016-04-01

    How to enhance the homing of human mesenchymal stem cells (hMSCs) to the target tissues remains a clinical challenge nowadays. To overcome this barrier, the mechanism responsible for the hMSCs migration and engraftment has to be defined. Currently, the exact mechanism involved in migration and adhesion of hMSCs remains unknown. Exchange protein directly activated by cAMP (Epac), a novel protein discovered in cAMP signaling pathway, may have a potential role in regulating cells adhesion and migration by triggering the downstream Rap family signaling cascades. However, the exact role of Epac in cells homing is elusive. Our study evaluated the role of Epac in the homing of hMSCs. We confirmed that hMSCs expressed functional Epac and its activation enhanced the migration and adhesion of hMSCs significantly. The Epac activation was further found to be contributed directly to the chemotactic responses induced by stromal cell derived factor-1 (SDF-1) which is a known chemokine in regulating hMSCs homing. These findings suggested Epac is connected to the SDF-1 signaling cascades. In conclusion, our study revealed that Epac plays a role in hMSCs homing by promoting adhesion and migration. Appropriate manipulation of Epac may enhance the homing of hMSCs and facilitate their future clinical applications.

  6. Arginine Methylation by PRMT1 Regulates Muscle Stem Cell Fate

    PubMed Central

    Blanc, Roméo Sébastien; Vogel, Gillian; Li, Xing; Yu, Zhenbao; Li, Shawn

    2016-01-01

    ABSTRACT Quiescent muscle stem cells (MSCs) become activated in response to skeletal muscle injury to initiate regeneration. Activated MSCs proliferate and differentiate to repair damaged fibers or self-renew to maintain the pool and ensure future regeneration. The balance between self-renewal, proliferation, and differentiation is a tightly regulated process controlled by a genetic cascade involving determinant transcription factors such as Pax7, Myf5, MyoD, and MyoG. Recently, there have been several reports about the role of arginine methylation as a requirement for epigenetically mediated control of muscle regeneration. Here we report that the protein arginine methyltransferase 1 (PRMT1) is expressed in MSCs and that conditional ablation of PRMT1 in MSCs using Pax7CreERT2 causes impairment of muscle regeneration. Importantly, PRMT1-deficient MSCs have enhanced cell proliferation after injury but are unable to terminate the myogenic differentiation program, leading to regeneration failure. We identify the coactivator of Six1, Eya1, as a substrate of PRMT1. We show that PRMT1 methylates Eya1 in vitro and that loss of PRMT1 function in vivo prevents Eya1 methylation. Moreover, we observe that PRMT1-deficient MSCs have reduced expression of Eya1/Six1 target MyoD due to disruption of Eya1 recruitment at the MyoD promoter and subsequent Eya1-mediated coactivation. These findings suggest that arginine methylation by PRMT1 regulates muscle stem cell fate through the Eya1/Six1/MyoD axis. PMID:27849571

  7. Signal integration by Ca2+ regulates intestinal stem cell activity

    PubMed Central

    Deng, Hansong; Gerencser, Akos A.; Jasper, Heinrich

    2015-01-01

    Summary Somatic stem cells (SCs) maintain tissue homeostasis by dynamically adjusting proliferation and differentiation in response to stress and metabolic cues. Here, we identify Ca2+ signaling as a central regulator of intestinal SC (ISC) activity in Drosophila. We find that dietary L-glutamate stimulates ISC division and gut growth. The metabotropic glutamate receptor (mGluR) is required in ISCs for this response and for an associated modulation of cytosolic Ca2+ oscillations that results in sustained high cytosolic Ca2+ concentrations. High cytosolic Ca2+ induces ISC proliferation by regulating Calcineurin and CREB - regulated transcriptional co-activator (CRTC). In response to a wide range of dietary and stress stimuli, ISCs reversibly transition between Ca2+ oscillation states that represent poised or activated modes of proliferation, respectively. We propose that the dynamic regulation of intracellular Ca2+ levels allows effective integration of diverse mitogenic signals in ISCs to tailor their proliferative activity to the needs of the tissue. PMID:26633624

  8. GATA-1 directly regulates Nanog in mouse embryonic stem cells

    SciTech Connect

    Li, Wen-Zhong; Ai, Zhi-Ying; Wang, Zhi-Wei; Chen, Lin-Lin; Guo, Ze-Kun; Zhang, Yong

    2015-09-25

    Nanog safeguards pluripotency in mouse embryonic stem cells (mESCs). Insight into the regulation of Nanog is important for a better understanding of the molecular mechanisms that control pluripotency of mESCs. In a silico analysis, we identify four GATA-1 putative binding sites in Nanog proximal promoter. The Nanog promoter activity can be significantly repressed by ectopic expression of GATA-1 evidenced by a promoter reporter assay. Mutation studies reveal that one of the four putative binding sites counts for GATA-1 repressing Nanog promoter activity. Direct binding of GATA-1 on Nanog proximal promoter is confirmed by electrophoretic mobility shift assay and chromatin immunoprecipitation. Our data provide new insights into the expanded regulatory circuitry that coordinates Nanog expression. - Highlights: • The Nanog proximal promoter conceives functional element for GATA-1. • GATA-1 occupies the Nanog proximal promoter in vitro and in vivo. • GATA-1 transcriptionally suppresses Nanog.

  9. VEGFA splicing: divergent isoforms regulate spermatogonial stem cell maintenance

    PubMed Central

    Sargent, Kevin M.; Clopton, Debra T.; Lu, Ningxia; Pohlmeier, William E.

    2015-01-01

    Despite being well-known for regulating angiogenesis in both normal and tumorigenic environments, vascular endothelial growth factor A (VEGFA) has been recently implicated in male fertility, namely in the maintenance of spermatogonial stem cells (SSC). The VEGFA gene can be spliced into multiple distinct isoforms that are either angiogenic or antiangiogenic in nature. Although studies have demonstrated the alternative splicing of VEGFA, including the divergent roles of the two isoform family types, many investigations do not differentiate between them. Data concerning VEGFA in the mammalian testis are limited, but the various angiogenic isoforms appear to promote seminiferous cord formation and to form a gradient across which cells may migrate. Treatment with either antiangiogenic isoforms of VEGFA or with inhibitors to angiogenic signaling impair these processes. Serendipitously, expression of KDR, the primary receptor for both types of VEGFA isoforms, was observed on male germ cells. These findings led to further investigation of the way that VEGFA elicits avascular functions within testes. Following treatment of donor perinatal male mice with either antiangiogenic VEGFA165b or angiogenic VEGFA164 isoforms, seminiferous tubules were less colonized following transplantation with cells from VEGFA165b-treated donors. Thus, VEGFA165b and possibly other antiangiogenic isoforms of VEGFA reduce SSC number either by promoting premature differentiation, inducing cell death, or by preventing SSC formation. Thus, angiogenic isoforms of VEGFA are hypothesized to promote SSC self-renewal, and the divergent isoforms are thought to balance one another to maintain SSC homeostasis in vivo. PMID:26553653

  10. Mitochondrial respiration regulates adipogenic differentiation of human mesenchymal stem cells.

    PubMed

    Zhang, Yanmin; Marsboom, Glenn; Toth, Peter T; Rehman, Jalees

    2013-01-01

    Human mesenchymal stem cells (MSCs) are adult multipotent stem cells which can be isolated from bone marrow, adipose tissue as well as other tissues and have the capacity to differentiate into a variety of mesenchymal cell types such as adipocytes, osteoblasts and chondrocytes. Differentiation of stem cells into mature cell types is guided by growth factors and hormones, but recent studies suggest that metabolic shifts occur during differentiation and can modulate the differentiation process. We therefore investigated mitochondrial biogenesis, mitochondrial respiration and the mitochondrial membrane potential during adipogenic differentiation of human MSCs. In addition, we inhibited mitochondrial function to assess its effects on adipogenic differentiation. Our data show that mitochondrial biogenesis and oxygen consumption increase markedly during adipogenic differentiation, and that reducing mitochondrial respiration by hypoxia or by inhibition of the mitochondrial electron transport chain significantly suppresses adipogenic differentiation. Furthermore, we used a novel approach to suppress mitochondrial activity using a specific siRNA-based knockdown of the mitochondrial transcription factor A (TFAM), which also resulted in an inhibition of adipogenic differentiation. Taken together, our data demonstrates that increased mitochondrial activity is a prerequisite for MSC differentiation into adipocytes. These findings suggest that metabolic modulation of adult stem cells can maintain stem cell pluripotency or direct adult stem cell differentiation.

  11. Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes.

    PubMed

    Li, Xiaoheng; Wang, Zhao; Jiang, Zhenming; Guo, Jingjing; Zhang, Yuxi; Li, Chenhao; Chung, Jinyong; Folmer, Janet; Liu, June; Lian, Qingquan; Ge, Renshan; Zirkin, Barry R; Chen, Haolin

    2016-03-08

    Testicular Leydig cells are the primary source of testosterone in males. Adult Leydig cells have been shown to arise from stem cells present in the neonatal testis. Once established, adult Leydig cells turn over only slowly during adult life, but when these cells are eliminated experimentally from the adult testis, new Leydig cells rapidly reappear. As in the neonatal testis, stem cells in the adult testis are presumed to be the source of the new Leydig cells. As yet, the mechanisms involved in regulating the proliferation and differentiation of these stem cells remain unknown. We developed a unique in vitro system of cultured seminiferous tubules to assess the ability of factors from the seminiferous tubules to regulate the proliferation of the tubule-associated stem cells, and their subsequent entry into the Leydig cell lineage. The proliferation of the stem Leydig cells was stimulated by paracrine factors including Desert hedgehog (DHH), basic fibroblast growth factor (FGF2), platelet-derived growth factor (PDGF), and activin. Suppression of proliferation occurred with transforming growth factor β (TGF-β). The differentiation of the stem cells was regulated positively by DHH, lithium- induced signaling, and activin, and negatively by TGF-β, PDGFBB, and FGF2. DHH functioned as a commitment factor, inducing the transition of stem cells to the progenitor stage and thus into the Leydig cell lineage. Additionally, CD90 (Thy1) was found to be a unique stem cell surface marker that was used to obtain purified stem cells by flow cytometry.

  12. Cell adhesion and mechanical stimulation in the regulation of mesenchymal stem cell differentiation

    PubMed Central

    Wang, Yang-Kao; Chen, Christopher S

    2013-01-01

    Stem cells have been shown to have the potential to provide a source of cells for applications to tissue engineering and organ repair. The mechanisms that regulate stem cell fate, however, mostly remain unclear. Mesenchymal stem cells (MSCs) are multipotent progenitor cells that are isolated from bone marrow and other adult tissues, and can be differentiated into multiple cell lineages, such as bone, cartilage, fat, muscles and neurons. Although previous studies have focused intensively on the effects of chemical signals that regulate MSC commitment, the effects of physical/mechanical cues of the microenvironment on MSC fate determination have long been neglected. However, several studies provided evidence that mechanical signals, both direct and indirect, played important roles in regulating a stem cell fate. In this review, we summarize a number of recent studies on how cell adhesion and mechanical cues influence the differentiation of MSCs into specific lineages. Understanding how chemical and mechanical cues in the microenvironment orchestrate stem cell differentiation may provide new insights into ways to improve our techniques in cell therapy and organ repair. PMID:23672518

  13. Wnt and BMP Signaling Crosstalk in Regulating Dental Stem Cells: Implications in Dental Tissue Engineering.

    PubMed

    Zhang, Fugui; Song, Jinglin; Zhang, Hongmei; Huang, Enyi; Song, Dongzhe; Tollemar, Viktor; Wang, Jing; Wang, Jinhua; Mohammed, Maryam; Wei, Qiang; Fan, Jiaming; Liao, Junyi; Zou, Yulong; Liu, Feng; Hu, Xue; Qu, Xiangyang; Chen, Liqun; Yu, Xinyi; Luu, Hue H; Lee, Michael J; He, Tong-Chuan; Ji, Ping

    2016-12-01

    Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling. Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance, essential oral functions and the quality of life. Regenerative dentistry holds great promise in treating oral/dental disorders. The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells, along with the signaling mechanisms governing stem cell self-renewal and differentiation. In this review, we first summarize the biological characteristics of seven types of dental stem cells, including dental pulp stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, periodontal ligament stem cells, alveolar bone-derived mesenchymal stem cells (MSCs), and MSCs from gingiva. We then focus on how these stem cells are regulated by bone morphogenetic protein (BMP) and/or Wnt signaling by examining the interplays between these pathways. Lastly, we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways. We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications. Thus, we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.

  14. Regulating myogenic differentiation of mesenchymal stem cells using thermosensitive hydrogels.

    PubMed

    Xu, Yanyi; Li, Zhenqing; Li, Xiaofei; Fan, Zhaobo; Liu, Zhenguo; Xie, Xiaoyun; Guan, Jianjun

    2015-10-01

    Stem cell therapy has potential to regenerate skeletal muscle tissue in ischemic limb. However, the delivered stem cells experience low rate of myogenic differentiation. Employing injectable hydrogels as stem cell carriers may enhance the myogenic differentiation as their modulus may be tailored to induce the differentiation. Yet current approaches used to manipulate hydrogel modulus often simultaneously vary other properties that also affect stem cell differentiation, such as chemical structure, composition and water content. Thus it is challenging to demonstrate the decoupled effect of hydrogel modulus on stem cell differentiation. In this report, we decoupled the hydrogel modulus from chemical structure, composition, and water content using injectable and thermosensitive hydrogels. The hydrogels were synthesized from N-isopropylacrylamide (NIPAAm), acrylic acid (AAc), and degradable macromer 2-hydroxyethyl methacrylate-oligomer [oligolatide, oligohydroxybutyrate, or oligo(trimethylene carbonate)]. We found that using the same monomer composition and oligomer chemical structure but different oligomer length can independently vary hydrogel modulus. Rat bone marrow mesenchymal stem cells (MSCs) were encapsulated in the hydrogels with elastic expansion moduli of 11, 20, and 40 kPa, respectively. After 14 days of culture, significant myogenic differentiation was achieved for the hydrogel with elastic expansion modulus of 20 kPa, as judged from both the gene and protein expression. In addition, MSCs exhibited an elastic expansion modulus-dependent proliferation rate. The most significant proliferation was observed in the hydrogel with elastic expansion modulus of 40 kPa. These results demonstrate that the developed injectable and thermosensitive hydrogels with suitable modulus has the potential to deliver stem cells into ischemic limb for enhanced myogenic differentiation and muscle regeneration. Stem cell therapy for skeletal muscle regeneration in ischemic limb

  15. Lrig1: a new master regulator of epithelial stem cells

    PubMed Central

    Ordóñez-Morán, Paloma; Huelsken, Joerg

    2012-01-01

    Nat Cell Biol 14 4, 401–408 03042012 The intestine represents the most vigorously renewing, adult epithelial tissue that makes maintenance of its homeostasis a delicate balance between proliferation, cell cycle arrest, migration, differentiation, and cell death. These processes are precisely controlled by a network of developmental signalling cascades, which include Wnt, Notch, BMP/TGFβ, and Hedgehog pathways. A new, elegant study by Wong et al (2012) now adds Lrig1 as a key player in the control of intestinal homeostasis. As for epidermal stem cells, Lrig1 limits the size of the intestinal progenitor compartment by dampening EGF/ErbB-triggered stem cell expansion. PMID:22433838

  16. Regulation of the adrenocortical stem cell niche: implications for disease

    PubMed Central

    Walczak, Elisabeth M.; Hammer, Gary D.

    2015-01-01

    Stem cells are endowed with the potential for self-renewal and multipotency. Pluripotent embryonic stem cells have an early role in the formation of the three germ layers (ectoderm, mesoderm and endoderm), whereas adult tissue stem cells and progenitor cells are critical mediators of organ homeostasis. The adrenal cortex is an exceptionally dynamic endocrine organ that is homeostatically maintained by paracrine and endocrine signals throughout postnatal life. In the past decade, much has been learned about the stem and progenitor cells of the adrenal cortex and the multiple roles that these cell populations have in normal development and homeostasis of the adrenal gland and in adrenal diseases. In this Review, we discuss the evidence for the presence of adrenocortical stem cells, as well as the various signalling molecules and transcriptional networks that are critical for the embryological establishment and postnatal maintenance of this vital population of cells. The implications of these pathways and cells in the pathophysiology of disease are also addressed. PMID:25287283

  17. Glycosaminoglycans (GAGs) and GAG mimetics regulate the behavior of stem cell differentiation.

    PubMed

    Wang, Mengmeng; Liu, Xiaoli; Lyu, Zhonglin; Gu, Hao; Li, Dan; Chen, Hong

    2017-02-01

    Glycosaminoglycans (GAGs) are linear sulfated polysaccharides that exist in most mammalian cells. By undergoing conjugation with various proteins, GAGs play important roles in a variety of bioactivities, including promoting stem cell differentiation. However, they have their own intrinsic disadvantages that limit their further applications for cell therapy and tissue engineering. Therefore, more and more GAG-mimetic materials have been studied as natural GAG analogs for emerging applications. This review explains the mechanism of how GAGs regulate stem cell differentiation and elaborates on the current progress of the applications of GAG-based materials on regulating stem cell differentiation. The types and applications of GAG-mimetic materials on regulating stem cell differentiation are introduced as well. Finally, the challenges and perspectives for GAGs and their mimetics in regulating stem cell differentiation are discussed.

  18. Transcriptional and post-transcriptional regulation of Drosophila germline stem cells and their differentiating progeny.

    PubMed

    White-Cooper, Helen; Caporilli, Simona

    2013-01-01

    In this chapter we will concentrate on the transcriptional and translational regulations that govern the development and differentiation of male germline cells. Our focus will be on the processes that occur during differentiation, that distinguish the differentiating population of cells from their stem cell parents. We discuss how these defining features are established as cells transit from a stem cell character to that of a fully committed differentiating cell. The focus will be on how GSCs differentiate, via spermatogonia, to spermatocytes. We will achieve this by first describing the transcriptional activity in the differentiating spermatocytes, cataloguing the known transcriptional regulators in these cells and then investigating how the transcription programme is set up by processes in the progentior cells. This process is particularly interesting to study from a stem cell perspective as the male GSCs are unipotent, so lineage decisions in differentiating progeny of stem cells, which occurs in many other stem cell systems, do not impinge on the behaviour of these cells.

  19. Professional regulation: a potentially valuable tool in responding to "stem cell tourism".

    PubMed

    Zarzeczny, Amy; Caulfield, Timothy; Ogbogu, Ubaka; Bell, Peter; Crooks, Valorie A; Kamenova, Kalina; Master, Zubin; Rachul, Christen; Snyder, Jeremy; Toews, Maeghan; Zoeller, Sonja

    2014-09-09

    The growing international market for unproven stem cell-based interventions advertised on a direct-to-consumer basis over the internet ("stem cell tourism") is a source of concern because of the risks it presents to patients as well as their supporters, domestic health care systems, and the stem cell research field. Emerging responses such as public and health provider-focused education and national regulatory efforts are encouraging, but the market continues to grow. Physicians play a number of roles in the stem cell tourism market and, in many jurisdictions, are members of a regulated profession. In this article, we consider the use of professional regulation to address physician involvement in stem cell tourism. Although it is not without its limitations, professional regulation is a potentially valuable tool that can be employed in response to problematic types of physician involvement in the stem cell tourism market. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Professional Regulation: A Potentially Valuable Tool in Responding to “Stem Cell Tourism”

    PubMed Central

    Zarzeczny, Amy; Caulfield, Timothy; Ogbogu, Ubaka; Bell, Peter; Crooks, Valorie A.; Kamenova, Kalina; Master, Zubin; Rachul, Christen; Snyder, Jeremy; Toews, Maeghan; Zoeller, Sonja

    2014-01-01

    The growing international market for unproven stem cell-based interventions advertised on a direct-to-consumer basis over the internet (“stem cell tourism”) is a source of concern because of the risks it presents to patients as well as their supporters, domestic health care systems, and the stem cell research field. Emerging responses such as public and health provider-focused education and national regulatory efforts are encouraging, but the market continues to grow. Physicians play a number of roles in the stem cell tourism market and, in many jurisdictions, are members of a regulated profession. In this article, we consider the use of professional regulation to address physician involvement in stem cell tourism. Although it is not without its limitations, professional regulation is a potentially valuable tool that can be employed in response to problematic types of physician involvement in the stem cell tourism market. PMID:25241736

  1. Haematopoietic stem cells require a highly regulated protein synthesis rate.

    PubMed

    Signer, Robert A J; Magee, Jeffrey A; Salic, Adrian; Morrison, Sean J

    2014-05-01

    Many aspects of cellular physiology remain unstudied in somatic stem cells, for example, there are almost no data on protein synthesis in any somatic stem cell. Here we set out to compare protein synthesis in haematopoietic stem cells (HSCs) and restricted haematopoietic progenitors. We found that the amount of protein synthesized per hour in HSCs in vivo was lower than in most other haematopoietic cells, even if we controlled for differences in cell cycle status or forced HSCs to undergo self-renewing divisions. Reduced ribosome function in Rpl24(Bst/+) mice further reduced protein synthesis in HSCs and impaired HSC function. Pten deletion increased protein synthesis in HSCs but also reduced HSC function. Rpl24(Bst/+) cell-autonomously rescued the effects of Pten deletion in HSCs; blocking the increase in protein synthesis, restoring HSC function, and delaying leukaemogenesis. Pten deficiency thus depletes HSCs and promotes leukaemia partly by increasing protein synthesis. Either increased or decreased protein synthesis impairs HSC function.

  2. Salmonella regulation of intestinal stem cells through the Wnt/β-catenin pathway

    PubMed Central

    Liu, Xingyin; Lu, Rong; Wu, Shaoping; Sun, Jun

    2010-01-01

    Recent studies have revealed that bacteria target stem cells for long-term survival in a Drosophila model. However, in mammalian models, little is known about bacterial infection and intestinal stem cells. Our study aims at understanding bacterial regulation of the intestinal stem cell in a Salmonella colitis mouse model. We found that Salmonella activates the Wnt/β-catenin signaling pathway that is known to regulate stem cells. We identified Salmonella protein AvrA that modulates Wnt signaling including upregulating Wnt expression, modifying β-catenin, increasing total β-catenin expression, and activating Wnt/β-catenin transcriptional activity in the intestinal epithelial cells. The numbers of stem cells and proliferative cells increased in the intestine infected with Salmonella expressing AvrA. Our study provides insights into bacterial infection and stem cell maintenance. PMID:20083111

  3. Interleukin-1 regulates hematopoietic progenitor and stem cells in the midgestation mouse fetal liver

    PubMed Central

    Orelio, Claudia; Peeters, Marian; Haak, Esther; van der Horn, Karin; Dzierzak, Elaine

    2009-01-01

    Background Hematopoietic progenitors are generated in the yolk sac and aorta-gonad-mesonephros region during early mouse development. At embryonic day 10.5 the first hematopoietic stem cells emerge in the aorta-gonad-mesonephros. Subsequently, hematopoietic stem cells and progenitors are found in the fetal liver. The fetal liver is a potent hematopoietic site, playing an important role in the expansion and differentiation of hematopoietic progenitors and hematopoietic stem cells. However, little is known concerning the regulation of fetal liver hematopoietic stem cells. In particular, the role of cytokines such as interleukin-1 in the regulation of hematopoietic stem cells in the embryo has been largely unexplored. Recently, we observed that the adult pro-inflammatory cytokine interleukin-1 is involved in regulating aorta-gonad-mesonephros hematopoietic progenitor and hematopoietic stem cell activity. Therefore, we set out to investigate whether interleukin-1 also plays a role in regulating fetal liver progenitor cells and hematopoietic stem cells. Design and Methods We examined the interleukin-1 ligand and receptor expression pattern in the fetal liver. The effects of interleukin-1 on hematopoietic progenitor cells and hematopoietic stem cells were studied by FACS and transplantation analyses of fetal liver explants, and in vivo effects on hematopoietic stem cell and progenitors were studied in Il1r1−/− embryos. Results We show that fetal liver hematopoietic progenitor cells express the IL-1RI and that interleukin-1 increases fetal liver hematopoiesis, progenitor cell activity and promotes hematopoietic cell survival. Moreover, we show that in Il1r1−/− embryos, hematopoietic stem cell activity is impaired and myeloid progenitor activity is increased. Conclusions The IL-1 ligand and receptor are expressed in the midgestation liver and act in the physiological regulation of fetal liver hematopoietic progenitor cells and hematopoietic stem cells. PMID

  4. Cell–cell interaction networks regulate blood stem and progenitor cell fate

    PubMed Central

    Kirouac, Daniel C; Madlambayan, Gerard J; Yu, Mei; Sykes, Edward A; Ito, Caryn; Zandstra, Peter W

    2009-01-01

    Communication networks between cells and tissues are necessary for homeostasis in multicellular organisms. Intercellular (between cell) communication networks are particularly relevant in stem cell biology, as stem cell fate decisions (self-renewal, proliferation, lineage specification) are tightly regulated based on physiological demand. We have developed a novel mathematical model of blood stem cell development incorporating cell-level kinetic parameters as functions of secreted molecule-mediated intercellular networks. By relation to quantitative cellular assays, our model is capable of predictively simulating many disparate features of both normal and malignant hematopoiesis, relating internal parameters and microenvironmental variables to measurable cell fate outcomes. Through integrated in silico and experimental analyses, we show that blood stem and progenitor cell fate is regulated by cell–cell feedback, and can be controlled non-cell autonomously by dynamically perturbing intercellular signalling. We extend this concept by demonstrating that variability in the secretion rates of the intercellular regulators is sufficient to explain heterogeneity in culture outputs, and that loss of responsiveness to cell–cell feedback signalling is both necessary and sufficient to induce leukemic transformation in silico. PMID:19638974

  5. Hedgehog signaling establishes precursors for germline stem cell niches by regulating cell adhesion

    PubMed Central

    Lin, Kun-Yang; Kao, Shih-Han

    2017-01-01

    Stem cells require different types of supporting cells, or niches, to control stem cell maintenance and differentiation. However, little is known about how those niches are formed. We report that in the development of the Drosophila melanogaster ovary, the Hedgehog (Hh) gradient sets differential cell affinity for somatic gonadal precursors to specify stromal intermingled cells, which contributes to both germline stem cell maintenance and differentiation niches in the adult. We also report that Traffic Jam (an orthologue of a large Maf transcription factor in mammals) is a novel transcriptional target of Hh signaling to control cell–cell adhesion by negative regulation of E-cadherin expression. Our results demonstrate the role of Hh signaling in niche establishment by segregating somatic cell lineages for differentiation. PMID:28363970

  6. Integrin-linked kinase regulates the niche of quiescent epidermal stem cells

    PubMed Central

    Morgner, Jessica; Ghatak, Sushmita; Jakobi, Tobias; Dieterich, Christoph; Aumailley, Monique; Wickström, Sara A.

    2015-01-01

    Stem cells reside in specialized niches that are critical for their function. Quiescent hair follicle stem cells (HFSCs) are confined within the bulge niche, but how the molecular composition of the niche regulates stem cell behaviour is poorly understood. Here we show that integrin-linked kinase (ILK) is a key regulator of the bulge extracellular matrix microenvironment, thereby governing the activation and maintenance of HFSCs. ILK mediates deposition of inverse laminin (LN)-332 and LN-511 gradients within the basement membrane (BM) wrapping the hair follicles. The precise BM composition tunes activities of Wnt and transforming growth factor-β pathways and subsequently regulates HFSC activation. Notably, reconstituting an optimal LN microenvironment restores the altered signalling in ILK-deficient cells. Aberrant stem cell activation in ILK-deficient epidermis leads to increased replicative stress, predisposing the tissue to carcinogenesis. Overall, our findings uncover a critical role for the BM niche in regulating stem cell activation and thereby skin homeostasis. PMID:26349061

  7. Ready, aim, shoot: stem cell regulation of the shoot apical meristem.

    PubMed

    Soyars, Cara L; James, Sean R; Nimchuk, Zachary L

    2016-02-01

    Plant shoot meristems contain stem cells that are continuously renewed to replenish cells that exit and differentiate during lateral organ formation. Complex cell-to-cell signaling systems balance division and differentiation. These center on ligand-receptor networks, hormone pathways, and transcriptional regulators that function in an integrated manner. In this review, we aim to highlight new findings in shoot stem cell regulation across species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Phosphofructokinase-1 Negatively Regulates Neurogenesis from Neural Stem Cells.

    PubMed

    Zhang, Fengyun; Qian, Xiaodan; Qin, Cheng; Lin, Yuhui; Wu, Haiyin; Chang, Lei; Luo, Chunxia; Zhu, Dongya

    2016-06-01

    Phosphofructokinase-1 (PFK-1), a major regulatory glycolytic enzyme, has been implicated in the functions of astrocytes and neurons. Here, we report that PFK-1 negatively regulates neurogenesis from neural stem cells (NSCs) by targeting pro-neural transcriptional factors. Using in vitro assays, we found that PFK-1 knockdown enhanced, and PFK-1 overexpression inhibited the neuronal differentiation of NSCs, which was consistent with the findings from NSCs subjected to 5 h of hypoxia. Meanwhile, the neurogenesis induced by PFK-1 knockdown was attributed to the increased proliferation of neural progenitors and the commitment of NSCs to the neuronal lineage. Similarly, in vivo knockdown of PFK-1 also increased neurogenesis in the dentate gyrus of the hippocampus. Finally, we demonstrated that the neurogenesis mediated by PFK-1 was likely achieved by targeting mammalian achaete-scute homologue-1 (Mash 1), neuronal differentiation factor (NeuroD), and sex-determining region Y (SRY)-related HMG box 2 (Sox2). All together, our results reveal PFK-1 as an important regulator of neurogenesis.

  9. Regulation of Stem Cell Fate by ROS-mediated Alteration of Metabolism

    PubMed Central

    Ryu, Jung Min; Lee, Hyun Jik; Jung, Young Hyun; Lee, Ki Hoon; Kim, Dah Ihm; Kim, Jeong Yeon; Ko, So Hee; Choi, Gee Euhn; Chai, Ing Ing; Song, Eun Ju; Oh, Ji Young; Lee, Sei-Jung; Han, Ho Jae

    2015-01-01

    Stem cells have attracted much attention due to their distinct features that support infinite self-renewal and differentiation into the cellular derivatives of three lineages. Recent studies have suggested that many stem cells both embryonic and adult stem cells reside in a specialized niche defined by hypoxic condition. In this respect, distinguishing functional differences arising from the oxygen concentration is important in understanding the nature of stem cells and in controlling stem cell fate for therapeutic purposes. ROS act as cellular signaling molecules involved in the propagation of signaling and the translation of environmental cues into cellular responses to maintain cellular homeostasis, which is mediated by the coordination of various cellular processes, and to adapt cellular activity to available bioenergetic sources. Thus, in this review, we describe the physiological role of ROS in stem cell fate and its effect on the metabolic regulation of stem cells. PMID:26019752

  10. Melatonin as a promising agent of regulating stem cell biology and its application in disease therapy.

    PubMed

    Zhang, Shuo; Chen, Simon; Li, Yuan; Liu, Yu

    2017-03-01

    Stem cells have emerged as an important approach to repair and regenerate damaged tissues or organs and show great therapeutic potential in a variety of diseases. However, the low survival of engrafted stem cells still remains a major challenge for stem cell therapy. As a major hormone from the pineal gland, melatonin has been shown to play an important role in regulating the physiological and pathological functions of stem cells, such as promoting proliferation, migration and differentiation. Thus, melatonin combined with stem cell transplantation displayed promising application potential in neurodegenerative diseases, liver cirrhosis, wound healing, myocardial infarction, kidney ischemia injury, osteoporosis, etc. It exerts its physiological and pathological functions through its anti-oxidant, anti-inflammatory, anti-apoptosis and anti-ageing properties. Here, we summarize recent advances on exploring the biological role of melatonin in stem cells, and discuss its potential applications in stem cell-based therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Regulation of Asymmetric Cell Division in Mammalian Neural Stem and Cancer Precursor Cells.

    PubMed

    Daynac, Mathieu; Petritsch, Claudia K

    Stem and progenitor cells are characterized by their abilities to self-renew and produce differentiated progeny. The balance between self-renewal and differentiation is achieved through control of cell division mode, which can be either asymmetric or symmetric. Failure to properly control cell division mode may result in premature depletion of the stem/progenitor cell pool or abnormal growth and impaired differentiation. In many tissues, including the brain, stem cells and progenitor cells undergo asymmetric cell division through the establishment of cell polarity. Cell polarity proteins are therefore potentially critical regulators of asymmetric cell division. Decrease or loss of asymmetric cell division can be associated with reduced differentiation common during aging or impaired remyelination as seen in demyelinating diseases. Progenitor-like glioma precursor cells show decreased asymmetric cell division rates and increased symmetric divisions, which suggests that asymmetric cell division suppresses brain tumor formation. Cancer stem cells, on the other hand, still undergo low rates of asymmetric cell division, which may provide them with a survival advantage during therapy. These findings led to the hypotheses that asymmetric cell divisions are not always tumor suppressive but can also be utilized to maintain a cancer stem cell population. Proper control of cell division mode is therefore not only deemed necessary to generate cellular diversity during development and to maintain adult tissue homeostasis but may also prevent disease and determine disease progression. Since brain cancer is most common in the adult and aging population, we review here the current knowledge on molecular mechanisms that regulate asymmetric cell divisions in the neural and oligodendroglial lineage during development and in the adult brain.

  12. Histone H2AX-dependent GABA(A) receptor regulation of stem cell proliferation.

    PubMed

    Andäng, Michael; Hjerling-Leffler, Jens; Moliner, Annalena; Lundgren, T Kalle; Castelo-Branco, Gonçalo; Nanou, Evanthia; Pozas, Ester; Bryja, Vitezslav; Halliez, Sophie; Nishimaru, Hiroshi; Wilbertz, Johannes; Arenas, Ernest; Koltzenburg, Martin; Charnay, Patrick; El Manira, Abdeljabbar; Ibañez, Carlos F; Ernfors, Patrik

    2008-01-24

    Stem cell self-renewal implies proliferation under continued maintenance of multipotency. Small changes in numbers of stem cells may lead to large differences in differentiated cell numbers, resulting in significant physiological consequences. Proliferation is typically regulated in the G1 phase, which is associated with differentiation and cell cycle arrest. However, embryonic stem (ES) cells may lack a G1 checkpoint. Regulation of proliferation in the 'DNA damage' S/G2 cell cycle checkpoint pathway is known for its role in the maintenance of chromatin structural integrity. Here we show that autocrine/paracrine gamma-aminobutyric acid (GABA) signalling by means of GABA(A) receptors negatively controls ES cell and peripheral neural crest stem (NCS) cell proliferation, preimplantation embryonic growth and proliferation in the boundary-cap stem cell niche, resulting in an attenuation of neuronal progenies from this stem cell niche. Activation of GABA(A) receptors leads to hyperpolarization, increased cell volume and accumulation of stem cells in S phase, thereby causing a rapid decrease in cell proliferation. GABA(A) receptors signal through S-phase checkpoint kinases of the phosphatidylinositol-3-OH kinase-related kinase family and the histone variant H2AX. This signalling pathway critically regulates proliferation independently of differentiation, apoptosis and overt damage to DNA. These results indicate the presence of a fundamentally different mechanism of proliferation control in these stem cells, in comparison with most somatic cells, involving proteins in the DNA damage checkpoint pathway.

  13. An X chromosome gene regulates hematopoietic stem cell kinetics

    PubMed Central

    Abkowitz, Janis L.; Taboada, Monica; Shelton, Grady H.; Catlin, Sandra N.; Guttorp, Peter; Kiklevich, J. Veronika

    1998-01-01

    Females are natural mosaics for X chromosome-linked genes. As X chromosome inactivation occurs randomly, the ratio of parental phenotypes among blood cells is approximately 1:1. Recently, however, ratios of greater than 3:1 have been observed in 38–56% of women over age 60. This could result from a depletion of hematopoietic stem cells (HSCs) with aging (and the maintenance of hematopoiesis by a few residual clones) or from myelodysplasia (the dominance of a neoplastic clone). Each possibility has major implications for chemotherapy and for transplantation in elderly patients. We report similar findings in longitudinal studies of female Safari cats and demonstrate that the excessive skewing that develops with aging results from a third mechanism that has no pathologic consequence, hemizygous selection. We show that there is a competitive advantage for all HSCs with a specific X chromosome phenotype and, thus, demonstrate that an X chromosome gene (or genes) regulates HSC replication, differentiation, and/or survival. PMID:9520458

  14. SHP2 regulates proliferation and tumorigenicity of glioma stem cells.

    PubMed

    Roccograndi, Laura; Binder, Zev A; Zhang, Logan; Aceto, Nicola; Zhang, Zhuo; Bentires-Alj, Mohamed; Nakano, Ichiro; Dahmane, Nadia; O'Rourke, Donald M

    2017-08-29

    SHP2 is a cytoplasmic protein tyrosine phosphatase (PTPase) involved in multiple signaling pathways and was the first identified proto-oncogene PTPase. Previous work in glioblastoma (GBM) has demonstrated the role of SHP2 PTPase activity in modulating the oncogenic phenotype of adherent GBM cell lines. Mutations in PTPN11, the gene encoding SHP2, have been identified with increasing frequency in GBM. Given the importance of SHP2 in developing neural stem cells, and the importance of glioma stem cells (GSCs) in GBM oncogenesis, we explored the functional role of SHP2 in GSCs. Using paired differentiated and stem cell primary cultures, we investigated the association of SHP2 expression with the tumor stem cell compartment. Proliferation and soft agar assays were used to demonstrate the functional contribution of SHP2 to cell growth and transformation. SHP2 expression correlated with SOX2 expression in GSC lines and was decreased in differentiated cells. Forced differentiation of GSCs by removal of growth factors, as confirmed by loss of SOX2 expression, also resulted in decreased SHP2 expression. Lentiviral-mediated knockdown of SHP2 inhibited proliferation. Finally, growth in soft-agar was similarly inhibited by loss of SHP2 expression. Our results show that SHP2 function is required for cell growth and transformation of the GSC compartment in GBM.

  15. Wnt/{beta}-catenin signaling regulates cancer stem cells in lung cancer A549 cells

    SciTech Connect

    Teng, Ying; Wang, Xiuwen; Wang, Yawei; Ma, Daoxin

    2010-02-12

    Wnt/{beta}-catenin signaling plays an important role not only in cancer, but also in cancer stem cells. In this study, we found that {beta}-catenin and OCT-4 was highly expressed in cisplatin (DDP) selected A549 cells. Stimulating A549 cells with lithium chloride (LiCl) resulted in accumulation of {beta}-catenin and up-regulation of a typical Wnt target gene cyclin D1. This stimulation also significantly enhanced proliferation, clone formation, migration and drug resistance abilities in A549 cells. Moreover, the up-regulation of OCT-4, a stem cell marker, was observed through real-time PCR and Western blotting. In a reverse approach, we inhibited Wnt signaling by knocking down the expression of {beta}-catenin using RNA interference technology. This inhibition resulted in down-regulation of the Wnt target gene cyclin D1 as well as the proliferation, clone formation, migration and drug resistance abilities. Meanwhile, the expression of OCT-4 was reduced after the inhibition of Wnt/{beta}-catenin signaling. Taken together, our study provides strong evidence that canonical Wnt signaling plays an important role in lung cancer stem cell properties, and it also regulates OCT-4, a lung cancer stem cell marker.

  16. Hypoxia-Regulated Delta-like 1 Homologue Enhances Cancer Cell Stemness and Tumorigenicity

    PubMed Central

    Kim, Yuri; Lin, Qun; Zelterman, Daniel; Yun, Zhong

    2010-01-01

    Reduced oxygenation, or hypoxia, inhibits differentiation and facilitates stem cell maintenance. Hypoxia commonly occurs in solid tumors and promotes malignant progression. Hypoxic tumors are aggressive and exhibit stem cell–like characteristics. It remains unclear, however, whether and how hypoxia regulates cancer cell differentiation and maintains cancer cell stemness. Here, we show that hypoxia increases the expression of the stem cell gene DLK1, or delta-like 1 homologue (Drosophila), in neuronal tumor cells. Inhibition of DLK1 enhances spontaneous differentiation, decreases clonogenicity, and reduces in vivo tumor growth. Overexpression of DLK1 inhibits differentiation and enhances tumorigenic potentials. We further show that the DLK1 cytoplasmic domain, especially Tyrosine339 and Serine355, is required for maintaining both clonogenicity and tumorigenicity. Because elevated DLK1 expression is found in many tumor types, our observations suggest that hypoxia and DLK1 may constitute an important stem cell pathway for the regulation of cancer stem cell–like functionality and tumorigenicity. PMID:19934310

  17. Regulation of plant stem cell quiescence by a brassinosteroid signaling module.

    PubMed

    Vilarrasa-Blasi, Josep; González-García, Mary-Paz; Frigola, David; Fàbregas, Norma; Alexiou, Konstantinos G; López-Bigas, Nuria; Rivas, Susana; Jauneau, Alain; Lohmann, Jan U; Benfey, Philip N; Ibañes, Marta; Caño-Delgado, Ana I

    2014-07-14

    The quiescent center (QC) maintains the activity of the surrounding stem cells within the root stem cell niche, yet specific molecular players sustaining the low rate of QC cell division remain poorly understood. Here, we identified a R2R3-MYB transcription factor, BRAVO (BRASSINOSTEROIDS AT VASCULAR AND ORGANIZING CENTER), acting as a cell-specific repressor of QC divisions in the primary root of Arabidopsis. Ectopic BRAVO expression restricts overall root growth and ceases root regeneration upon damage of the stem cells, demonstrating the role of BRAVO in counteracting Brassinosteroid (BR)-mediated cell division in the QC cells. Interestingly, BR-regulated transcription factor BES1 (BRI1-EMS SUPRESSOR 1) directly represses and physically interacts with BRAVO in vivo, creating a switch that modulates QC divisions at the root stem cell niche. Together, our results define a mechanism for BR-mediated regulation of stem cell quiescence in plants.

  18. The topographical regulation of embryonic stem cell differentiation.

    PubMed Central

    Murray, Patricia; Edgar, David

    2004-01-01

    The potential use of pluripotent stem cells for tissue repair or replacement is now well recognized. While the ability of embryonic stem (ES) cells to differentiate into all cells of the body is undisputed, their use is currently restricted by our limited knowledge of the mechanisms controlling their differentiation. This review discusses recent work by ourselves and others investigating the intercellular signalling events that occur within aggregates of mouse ES cells. The work illustrates that the processes of ES cell differentiation, epithelialization and programmed cell death are dependent upon their location within the aggregates and coordinated by the extracellular matrix. Establishment of the mechanisms involved in these events is not only of use for the manipulation of ES cells themselves, but it also throws light on the ways in which differentiation is coordinated during embryogenesis. PMID:15306413

  19. Micro-RNA mediated regulation of proliferation, self-renewal and differentiation of mammalian stem cells

    PubMed Central

    Hime, Gary R

    2009-01-01

    Metazoan growth and development is maintained by populations of undifferentiated cells, commonly known as stem cells. Stem cells possess several characteristic properties, including dividing through self-renewing divisions and generating progeny that differentiate to have specialized cell fates. Multiple signaling pathways have been identified which coordinate stem cell proliferation with maintenance and differentiation. Relatively recently, the small, non-protein coding microRNAs (miRNAs) have been identified to function as important regulators in stem cell development. Individual miRNAs are capable of directing the translational repression of many mRNAs targets, generating widespread changes in gene expression. In addition, dysfunction of miRNA expression is commonly associated with cancer development. Cancer stem cells, which are likely responsible for initiating and maintaining tumorigenesis, share many similarities with stem cells and some mechanisms of miRNA function may be in common between these two cell types. PMID:19829062

  20. Prion Protein Expression Regulates Embryonic Stem Cell Pluripotency and Differentiation

    PubMed Central

    Miranda, Alberto; Pericuesta, Eva

    2011-01-01

    Cellular prion protein (PRNP) is a glycoprotein involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs). Although the physiological function of PRNP is largely unknown, its key role in prion infection has been extensively documented. This study examines the functionality of PRNP during the course of embryoid body (EB) differentiation in mouse Prnp-null (KO) and WT embryonic stem cell (ESC) lines. The first feature observed was a new population of EBs that only appeared in the KO line after 5 days of differentiation. These EBs were characterized by their expression of several primordial germ cell (PGC) markers until Day 13. In a comparative mRNA expression analysis of genes playing an important developmental role during ESC differentiation to EBs, Prnp was found to participate in the transcription of a key pluripotency marker such as Nanog. A clear switching off of this gene on Day 5 was observed in the KO line as opposed to the WT line, in which maximum Prnp and Nanog mRNA levels appeared at this time. Using a specific antibody against PRNP to block PRNP pathways, reduced Nanog expression was confirmed in the WT line. In addition, antibody-mediated inhibition of ITGB5 (integrin αvβ5) in the KO line rescued the low expression of Nanog on Day 5, suggesting the regulation of Nanog transcription by Prnp via this Itgb5. mRNA expression analysis of the PRNP-related proteins PRND (Doppel) and SPRN (Shadoo), whose PRNP function is known to be redundant, revealed their incapacity to compensate for the absence of PRNP during early ESC differentiation. Our findings provide strong evidence for a relationship between Prnp and several key pluripotency genes and attribute Prnp a crucial role in regulating self-renewal/differentiation status of ESC, confirming the participation of PRNP during early embryogenesis. PMID:21483752

  1. Prion protein expression regulates embryonic stem cell pluripotency and differentiation.

    PubMed

    Miranda, Alberto; Pericuesta, Eva; Ramírez, Miguel Ángel; Gutierrez-Adan, Alfonso

    2011-04-04

    Cellular prion protein (PRNP) is a glycoprotein involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs). Although the physiological function of PRNP is largely unknown, its key role in prion infection has been extensively documented. This study examines the functionality of PRNP during the course of embryoid body (EB) differentiation in mouse Prnp-null (KO) and WT embryonic stem cell (ESC) lines. The first feature observed was a new population of EBs that only appeared in the KO line after 5 days of differentiation. These EBs were characterized by their expression of several primordial germ cell (PGC) markers until Day 13. In a comparative mRNA expression analysis of genes playing an important developmental role during ESC differentiation to EBs, Prnp was found to participate in the transcription of a key pluripotency marker such as Nanog. A clear switching off of this gene on Day 5 was observed in the KO line as opposed to the WT line, in which maximum Prnp and Nanog mRNA levels appeared at this time. Using a specific antibody against PRNP to block PRNP pathways, reduced Nanog expression was confirmed in the WT line. In addition, antibody-mediated inhibition of ITGB5 (integrin αvβ5) in the KO line rescued the low expression of Nanog on Day 5, suggesting the regulation of Nanog transcription by Prnp via this Itgb5. mRNA expression analysis of the PRNP-related proteins PRND (Doppel) and SPRN (Shadoo), whose PRNP function is known to be redundant, revealed their incapacity to compensate for the absence of PRNP during early ESC differentiation. Our findings provide strong evidence for a relationship between Prnp and several key pluripotency genes and attribute Prnp a crucial role in regulating self-renewal/differentiation status of ESC, confirming the participation of PRNP during early embryogenesis.

  2. Prohibitin 2 regulates cell proliferation and mitochondrial cristae morphogenesis in planarian stem cells.

    PubMed

    Rossi, Leonardo; Bonuccelli, Lucia; Iacopetti, Paola; Evangelista, Monica; Ghezzani, Claudio; Tana, Luigi; Salvetti, Alessandra

    2014-12-01

    Prohibitins are pleiotropic proteins, whose multiple roles are emerging as key elements in the regulation of cell survival and proliferation. Indeed, prohibitins interact with several intracellular proteins strategically involved in the regulation of cell cycle progression in response to extracellular growth signals. Prohibitins also have regulatory functions in mitochondrial fusion and cristae morphogenesis, phenomena related to the ability of self-renewing embryonic stem cells to undergo differentiation, during which mitochondria develop numerous cristae, increase in number, and generate an extensive reticular network. We recently identified a Prohibitin 2 homolog (DjPhb2) that is expressed in adult stem cells (neoblasts) of planarians, a well-known model system for in vivo studies on stem cells and tissue regeneration. Here, we show that in DjPhb2 silenced planarians, most proliferating cells disappear, with the exception of a subpopulation of neoblasts localized along the dorsal body midline. Neoblast depletion impairs regeneration and, finally, leads animals to death. Our in vivo findings demonstrate that prohibitin 2 plays an important role in regulating stem cell biology, being involved in both the control of cell cycle progression and mitochondrial cristae morphogenesis.

  3. 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.

  4. Cell cycle regulation of embryonic stem cells and mouse embryonic fibroblasts lacking functional Pax7

    PubMed Central

    Czerwinska, Areta M.; Nowacka, Joanna; Aszer, Magdalena; Fogtman, Anna; Iwanicka-Nowicka, Roksana; Jańczyk-Ilach, Katarzyna; Ciemerych, Maria A.; Grabowska, Iwona

    2016-01-01

    ABSTRACT The transcription factor Pax7 plays a key role during embryonic myogenesis and in adult organisms in that it sustains the proper function of satellite cells, which serve as adult skeletal muscle stem cells. Recently we have shown that lack of Pax7 does not prevent the myogenic differentiation of pluripotent stem cells. In the current work we show that the absence of functional Pax7 in differentiating embryonic stem cells modulates cell cycle facilitating their proliferation. Surprisingly, deregulation of Pax7 function also positively impacts at the proliferation of mouse embryonic fibroblasts. Such phenotypes seem to be executed by modulating the expression of positive cell cycle regulators, such as cyclin E. PMID:27610933

  5. Role of key regulators of the cell cycle in maintenance of hematopoietic stem cells.

    PubMed

    Matsumoto, Akinobu; Nakayama, Keiichi I

    2013-02-01

    Hematopoietic stem cells (HSCs) are characterized by pluripotentiality and self-renewal ability. To maintain a supply of mature blood cells and to avoid HSC exhaustion during the life span of an organism, most HSCs remain quiescent, with only a limited number entering the cell cycle. The molecular mechanisms by which quiescence is maintained in HSCs are addressed, with recent genetic studies having provided important insight into the relation between the cell cycle activity and stemness of HSCs. The cell cycle is tightly regulated in HSCs by complex factors. Key regulators of the cell cycle in other cell types-including cyclins, cyclin-dependent kinases (CDKs), the retinoblastoma protein family, the transcription factor E2F, and CDK inhibitors-also contribute to such regulation in HSCs. Most, but not all, of these regulators are necessary for maintenance of HSCs, with abnormal activation or suppression of the cell cycle resulting in HSC exhaustion. The cell cycle in HSCs is also regulated by external factors such as cytokines produced by niche cells as well as by the ubiquitin-proteasome pathway. Studies of the cell cycle in HSCs may shed light on the pathogenesis of hematopoietic disorders, serve as a basis for the development of new therapeutic strategies for such disorders, prove useful for the expansion of HSCs in vitro as a possible replacement for blood transfusion, and provide insight into stem cell biology in general. This article is part of a Special Issue entitled Biochemistry of Stem Cells. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. microRNA-103/107 family regulates multiple epithelial stem cell characteristics

    PubMed Central

    Peng, Han; Park, Jong Kook; Katsnelson, Julia; Kaplan, Nihal; Yang, Wending; Getsios, Spiro; Lavker, Robert M.

    2015-01-01

    The stem cell niche is thought to affect cell cycle quiescence, proliferative capacity and communication between stem cells and their neighbors. How these activities are controlled is not completely understood. Here we define a microRNA family (miRs-103/107) preferentially expressed in the stem cell-enriched limbal epithelium that regulates and integrates these stem cell characteristics. miRs-103/107 target the ribosomal kinase p90RSK2, thereby arresting cells in G0/G1 and contributing to a slow-cycling phenotype. Furthermore, miRs-103/107 increase the proliferative capacity of keratinocytes by targeting Wnt3a, which enhances Sox 9 and YAP 1 levels and thus promotes a stem cell phenotype. This miRNA family also regulates keratinocyte cell-cell communication by targeting: (i) the scaffolding protein NEDD9, preserving E-cadherin-mediated cell adhesion; and (ii) the tyrosine phosphatase PTPRM, which negatively regulates connexin 43-based gap junctions. We propose that such regulation of cell communication and adhesion molecules maintains the integrity of the stem cell niche ultimately preserving self-renewal, a hallmark of epithelial stem cells. PMID:25639731

  7. GATA2 regulates differentiation of bone marrow-derived mesenchymal stem cells

    PubMed Central

    Kamata, Mayumi; Okitsu, Yoko; Fujiwara, Tohru; Kanehira, Masahiko; Nakajima, Shinji; Takahashi, Taro; Inoue, Ai; Fukuhara, Noriko; Onishi, Yasushi; Ishizawa, Kenichi; Shimizu, Ritsuko; Yamamoto, Masayuki; Harigae, Hideo

    2014-01-01

    The bone marrow microenvironment comprises multiple cell niches derived from bone marrow mesenchymal stem cells. However, the molecular mechanism of bone marrow mesenchymal stem cell differentiation is poorly understood. The transcription factor GATA2 is indispensable for hematopoietic stem cell function as well as other hematopoietic lineages, suggesting that it may maintain bone marrow mesenchymal stem cells in an immature state and also contribute to their differentiation. To explore this possibility, we established bone marrow mesenchymal stem cells from GATA2 conditional knockout mice. Differentiation of GATA2-deficient bone marrow mesenchymal stem cells into adipocytes induced accelerated oil-drop formation. Further, GATA2 loss- and gain-of-function analyses based on human bone marrow mesenchymal stem cells confirmed that decreased and increased GATA2 expression accelerated and suppressed bone marrow mesenchymal stem cell differentiation to adipocytes, respectively. Microarray analysis of GATA2 knockdowned human bone marrow mesenchymal stem cells revealed that 90 and 189 genes were upregulated or downregulated by a factor of 2, respectively. Moreover, gene ontology analysis revealed significant enrichment of genes involved in cell cycle regulation, and the number of G1/G0 cells increased after GATA2 knockdown. Concomitantly, cell proliferation was decreased by GATA2 knockdown. When GATA2 knockdowned bone marrow mesenchymal stem cells as well as adipocytes were cocultured with CD34-positive cells, hematopoietic stem cell frequency and colony formation decreased. We confirmed the existence of pathological signals that decrease and increase hematopoietic cell and adipocyte numbers, respectively, characteristic of aplastic anemia, and that suppress GATA2 expression in hematopoietic stem cells and bone marrow mesenchymal stem cells. PMID:25150255

  8. GATA2 regulates differentiation of bone marrow-derived mesenchymal stem cells.

    PubMed

    Kamata, Mayumi; Okitsu, Yoko; Fujiwara, Tohru; Kanehira, Masahiko; Nakajima, Shinji; Takahashi, Taro; Inoue, Ai; Fukuhara, Noriko; Onishi, Yasushi; Ishizawa, Kenichi; Shimizu, Ritsuko; Yamamoto, Masayuki; Harigae, Hideo

    2014-11-01

    The bone marrow microenvironment comprises multiple cell niches derived from bone marrow mesenchymal stem cells. However, the molecular mechanism of bone marrow mesenchymal stem cell differentiation is poorly understood. The transcription factor GATA2 is indispensable for hematopoietic stem cell function as well as other hematopoietic lineages, suggesting that it may maintain bone marrow mesenchymal stem cells in an immature state and also contribute to their differentiation. To explore this possibility, we established bone marrow mesenchymal stem cells from GATA2 conditional knockout mice. Differentiation of GATA2-deficient bone marrow mesenchymal stem cells into adipocytes induced accelerated oil-drop formation. Further, GATA2 loss- and gain-of-function analyses based on human bone marrow mesenchymal stem cells confirmed that decreased and increased GATA2 expression accelerated and suppressed bone marrow mesenchymal stem cell differentiation to adipocytes, respectively. Microarray analysis of GATA2 knockdowned human bone marrow mesenchymal stem cells revealed that 90 and 189 genes were upregulated or downregulated by a factor of 2, respectively. Moreover, gene ontology analysis revealed significant enrichment of genes involved in cell cycle regulation, and the number of G1/G0 cells increased after GATA2 knockdown. Concomitantly, cell proliferation was decreased by GATA2 knockdown. When GATA2 knockdowned bone marrow mesenchymal stem cells as well as adipocytes were cocultured with CD34-positive cells, hematopoietic stem cell frequency and colony formation decreased. We confirmed the existence of pathological signals that decrease and increase hematopoietic cell and adipocyte numbers, respectively, characteristic of aplastic anemia, and that suppress GATA2 expression in hematopoietic stem cells and bone marrow mesenchymal stem cells. Copyright© Ferrata Storti Foundation.

  9. Evolutionally dynamic L1 regulation in embryonic stem cells

    PubMed Central

    Castro-Diaz, Nathaly; Ecco, Gabriela; Coluccio, Andrea; Kapopoulou, Adamandia; Yazdanpanah, Benyamin; Friedli, Marc; Duc, Julien; Jang, Suk Min; Turelli, Priscilla; Trono, Didier

    2014-01-01

    Mobile elements are important evolutionary forces that challenge genomic integrity. Long interspersed element-1 (L1, also known as LINE-1) is the only autonomous transposon still active in the human genome. It displays an unusual pattern of evolution, with, at any given time, a single active L1 lineage amplifying to thousands of copies before getting replaced by a new lineage, likely under pressure of host restriction factors, which act notably by silencing L1 expression during early embryogenesis. Here, we demonstrate that in human embryonic stem (hES) cells, KAP1 (KRAB [Krüppel-associated box domain]-associated protein 1), the master cofactor of KRAB-containing zinc finger proteins (KRAB-ZFPs) previously implicated in the restriction of endogenous retroviruses, represses a discrete subset of L1 lineages predicted to have entered the ancestral genome between 26.8 million and 7.6 million years ago. In mice, we documented a similar chronologically conditioned pattern, albeit with a much contracted time scale. We could further identify an L1-binding KRAB-ZFP, suggesting that this rapidly evolving protein family is more globally responsible for L1 recognition. KAP1 knockdown in hES cells induced the expression of KAP1-bound L1 elements, but their younger, human-specific counterparts (L1Hs) were unaffected. Instead, they were stimulated by depleting DNA methyltransferases, consistent with recent evidence demonstrating that the PIWI–piRNA (PIWI-interacting RNA) pathway regulates L1Hs in hES cells. Altogether, these data indicate that the early embryonic control of L1 is an evolutionarily dynamic process and support a model in which newly emerged lineages are first suppressed by DNA methylation-inducing small RNA-based mechanisms before KAP1-recruiting protein repressors are selected. PMID:24939876

  10. REST regulates oncogenic properties of glioblastoma stem cells

    PubMed Central

    Kamal, Mohamed M.; Sathyan, Pratheesh; Singh, Sanjay K.; Zinn, Pascal O.; Marisetty, Anantha L.; Liang, Shoudan; Gumin, Joy; El-Mesallamy, Hala Osman; Suki, Dima; Colman, Howard; Fuller, Gregory N.; Lang, Frederick F.; Majumder, Sadhan

    2013-01-01

    Glioblastoma multiforme (GBM) tumors are the most common malignant primary brain tumors in adults. Although many GBM tumors are believed to be caused by self-renewing, glioblastoma-derived stem-like cells (GSCs), the mechanisms that regulate self-renewal and other oncogenic properties of GSCs are only now being unraveled. Here we showed that GSCs derived from GBM patient specimens express varying levels of the transcriptional repressor REST, suggesting heterogeneity across different GSC lines. Loss- and gain-of-function experiments indicated that REST maintains self-renewal of GSCs. High REST-expressing GSCs (HR-GSCs) produced tumors histopathologically distinct from those generated by low REST-expressing GSCs (LR-GSCs) in orthotopic mouse brain tumor models. Knockdown of REST in HR-GSCs resulted in increased survival in GSC-transplanted mice and produced tumors with higher apoptotic and lower invasive properties. Conversely, forced expression of exogenous REST in LR-GSCs produced decreased survival in mice and produced tumors with lower apoptotic and higher invasive properties, similar to HR-GSCs. Thus, based on our results, we propose that a novel function of REST is to maintain self-renewal and other oncogenic properties of GSCs and that REST can play a major role in mediating tumorigenicity in GBM. PMID:22228704

  11. The Retinoblastoma pathway regulates stem cell proliferation in freshwater planarians.

    PubMed

    Zhu, Shu Jun; Pearson, Bret J

    2013-01-15

    Freshwater planarians are flatworms of the Lophotrochozoan superphylum and are well known for their regenerative abilities, which rely on a large population of pluripotent adult stem cells. However, the mechanisms by which planarians maintain a precise population of adult stem cells while balancing proliferation and cell death, remain to be elucidated. Here we have identified, characterized, and functionally tested the core Retinoblastoma (Rb) pathway components in planarian adult stem cell biology. The Rb pathway is an ancient and conserved mechanism of proliferation control from plants to animals and is composed of three core components: an Rb protein, and a transcription factor heterodimer of E2F and DP proteins. Although the planarian genome contains all components of the Rb pathway, we found that they have undergone gene loss from the ancestral state, similar to other species in their phylum. The single Rb homolog (Smed-Rb) was highly expressed in planarian stem cells and was required for stem cell maintenance, similar to the Rb-homologs p107 and p130 in vertebrates. We show that planarians and their phylum have undergone the most severe reduction in E2F genes observed thus far, and the single remaining E2F was predicted to be a repressive-type E2F (Smed-E2F4-1). Knockdown of either Smed-E2F4-1 or its dimerization partner Dp (Smed-Dp) by RNAi resulted in temporary hyper-proliferation. Finally, we showed that known Rb-interacting genes in other systems, histone deacetylase 1 and cyclinD (Smed-HDAC1; Smed-cycD), were similar to Rb in expression and phenotypes when knocked down by RNAi, suggesting that these established interactions with Rb may also be conserved in planarians. Together, these results showed that planarians use the conserved components of the Rb tumor suppressor pathway to control proliferation and cell survival.

  12. Dynamic regulation of cancer stem cells and clinical challenges.

    PubMed

    Ni, Chao; Huang, Jian

    2013-04-01

    A small population of cancer cells referred to as cancer stem cells (CSCs) have received particular attention, as they have been revealed to acquire stem cell-like properties and become the main cause of tumor propagation, metastasis and drug resistance. The CSC theory of tumor formation was believed to follow the hierarchical model initially, and therefore many CSC-targeted therapy methods were expected to cure cancer by eradicating CSCs. However, subsequent CSC research has revealed that rather than a distinct entity, the CSC is a dynamic status that can be continually dedifferentiated from progenitor or differentiated cancer cells. Elucidation of this bidirectional transition mechanism would help perfect the CSC theory and be of great value in the development of more effective anti-cancer drugs. Here, we reviewed the mechanisms of reciprocal conversion between non-CSCs and CSCs. Moreover, several approaches of target CSCs and non-CSCs together with unbiased eradication of all cancer cells are also discussed.

  13. Roles of limbal microvascular net and limbal stroma in regulating maintenance of limbal epithelial stem cells.

    PubMed

    Huang, Minghai; Wang, Bowen; Wan, Pengxia; Liang, Xuanwei; Wang, Xiaoran; Liu, Ying; Zhou, Qiang; Wang, Zhichong

    2015-02-01

    Knowledge of the microenvironment (niche) of stem cells is helpful for stem-cell-based regenerative medicine. In the eye, limbal epithelial stem cells (corneal epithelial stem cells) provide the self-renewal capacity of the corneal epithelium and are essential for maintaining corneal transparency and vision. Limbal epithelial stem cell deficiency results in significant visual deterioration. Successful treatment of this type of blinding disease requires studies of the limbal epithelial stem cells and their microenvironment. We investigate the function of the limbal microvascular net and the limbal stroma in the maintenace of the limbal epithelial stem cell niche in vivo and examine the regulation of limbal epithelial stem cell survival, proliferation and differentiation in vivo. We assess the temporal and spatial changes in the expression patterns of the following markers during a six-month follow-up of various rabbit limbal autograft transplantation models: vascular endothelial cell marker CD31, corneal epithelium differentiation marker K3, limbal epithelial stem-cell-associated markers P63 and ABCG2 and proliferating cell nuclear marker Ki67. Our results suggest that limbal epithelial stem cells cannot maintain their stemness or proliferation without the support of the limbal microvascular net microenvironment. Thus, both the limbal microvascular net and the limbal stroma play important roles as components of the limbal epithelial stem cell niche maintaining limbal epithelial stem cell survival and proliferation and the avoidance of differentiation. The limbal stroma constitutes the structural basis of the limbal epithelial stem cell niche and the limbal microvascular net is a requirement for this niche. These new insights should aid the eventual construction of tissue-engineered cornea for corneal blind patients in the future.

  14. The Cancer Stem Cell Niche: How Essential is the Niche in Regulating Stemness of Tumor Cells?

    PubMed Central

    Plaks, Vicki; Kong, Niwen; Werb, Zena

    2015-01-01

    Cancer stem cells (CSCs) are tumor cells that have the principal properties of self-renewal, clonal tumor initiation capacity and clonal long-term repopulation potential. CSCs reside in niches, which are anatomically distinct regions within the tumor microenvironment. These niches maintain the principle properties of CSCs, preserve their phenotypic plasticity, protect them from the immune system and facilitate their metastatic potential. In this perspective, we focus on the CSC niche and discuss its contribution to tumor initiation and progression. Since CSCs survive many commonly employed cancer therapies, we examine the prospects of targeting the niche components as preferable therapeutic targets. PMID:25748930

  15. p73 regulates maintenance of neural stem cell

    SciTech Connect

    Agostini, Massimiliano; Tucci, Paola; Bano, Daniele; Nicotera, Pierluigi; McKeon, Frank; Melino, Gerry

    2010-12-03

    Research highlights: {yields} TAp73 is expressed in neural stem cells and its expression increases following their differentiation. {yields} Neural stem cells from p73 null mice have a reduced proliferative potential. {yields} p73-deficient neural stem cells show reduced expression of members of the Sox-2 and Notch gene families. {yields} Neurogenic areas are reduced in the brains of embryonic and adult p73-/- mice. -- Abstract: p73, a member of the p53 family, is a transcription factor that plays a key role in many biological processes. In the present study, we show that TAp73 is expressed in neural stem cells (NSC) and its expression increases following their differentiation. NSC from p73 null mice have a reduced proliferative potential, together with reduced expression of members of the Sox-2 and Notch gene families known to be important for NSC proliferation. In parallel with this in vitro data, the width of the neurogenic areas was reduced in the brains of embryonic and adult p73-/- mice. These data suggest that p73, and in particular TAp73, is important for maintenance of the NSC pool.

  16. Genome-wide RNAi screen identifies networks involved in intestinal stem cell regulation in Drosophila.

    PubMed

    Zeng, Xiankun; Han, Lili; Singh, Shree Ram; Liu, Hanhan; Neumüller, Ralph A; Yan, Dong; Hu, Yanhui; Liu, Ying; Liu, Wei; Lin, Xinhua; Hou, Steven X

    2015-02-24

    The intestinal epithelium is the most rapidly self-renewing tissue in adult animals and maintained by intestinal stem cells (ISCs) in both Drosophila and mammals. To comprehensively identify genes and pathways that regulate ISC fates, we performed a genome-wide transgenic RNAi screen in adult Drosophila intestine and identified 405 genes that regulate ISC maintenance and lineage-specific differentiation. By integrating these genes into publicly available interaction databases, we further developed functional networks that regulate ISC self-renewal, ISC proliferation, ISC maintenance of diploid status, ISC survival, ISC-to-enterocyte (EC) lineage differentiation, and ISC-to-enteroendocrine (EE) lineage differentiation. By comparing regulators among ISCs, female germline stem cells, and neural stem cells, we found that factors related to basic stem cell cellular processes are commonly required in all stem cells, and stem-cell-specific, niche-related signals are required only in the unique stem cell type. Our findings provide valuable insights into stem cell maintenance and lineage-specific differentiation.

  17. The Italian Way to Stem Cell Research: Rethinking the Role of Catholic Religion in Shaping Italian Stem Cell Research Regulations.

    PubMed

    Beltrame, Lorenzo

    2016-01-21

    Stem cell research regulations are highly variable across nations, notwithstanding shared and common ethical concerns. Dominant in political debates has been the so-called embryo question. However, the permissibility of human embryonic stem cell (hESC) research varies among national regulatory frameworks. Scholars have explained differences by resorting to notions of political culture, traditions of ethical reasoning, discursive strategies and political manoeuvring of involved actors. Explanations based on the role of religion or other cultural structural variables are also employed. This paper analyses the emerging of the Italian regulatory framework on stem cell research using an analytical framework that considers the interplay between cultural structural features, political culture, traditions of ethical reasoning, institutional settings and the discursive and political agency of the actors involved. It aims also to explain the role of Roman Catholic Church in shaping the Italian stem cell research regulation not by treating religion as an autonomous causal factor, but through the analysis of the agency of Catholic and allied actors in the Italian political culture and institutional setting. © 2016 John Wiley & Sons Ltd.

  18. 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

  19. Immune Influence on Adult Neural Stem Cell Regulation and Function

    PubMed Central

    Carpentier, Pamela A.; Palmer, Theo D.

    2009-01-01

    Neural stem cells (NSCs) lie at the heart of central nervous system development and repair, and deficiency or dysregulation of NSCs or their progeny can have significant consequences at any stage of life. Immune signaling is emerging as one of the influential variables that define resident NSC behavior. Perturbations in local immune signaling accompany virtually every injury or disease state and signaling cascades that mediate immune activation, resolution, or chronic persistence influence resident stem and progenitor cells. Some aspects of immune signaling are beneficial, promoting intrinsic plasticity and cell replacement, while others appear to inhibit the very type of regenerative response that might restore or replace neural networks lost in injury or disease. Here we review known and speculative roles that immune signaling plays in the postnatal and adult brain, focusing on how environments encountered in disease or injury may influence the activity and fate of endogenous or transplanted NSCs. PMID:19840551

  20. Epigenetic regulation during the differentiation of stem cells to germ cells.

    PubMed

    Sun, Yuan-Chao; Wang, Yong-Yong; Ge, Wei; Cheng, Shun-Feng; Dyce, Paul W; Shen, Wei

    2017-08-22

    Gametogenesis is an essential process to ensure the transfer of genetic information from one generation to the next. It also provides a mechanism by which genetic evolution can take place. Although the genome of primordial germ cells (PGCs) is exactly the same with somatic cells within an organism, there are significant differences between their developments. For example, PGCs eventually undergo meiosis to become functional haploid gametes, and prior to that they undergo epigenetic imprinting which greatly alter their genetic regulation. Epigenetic imprinting of PGCs involves the erasure of DNA methylation and the reestablishment of them during sperm and oocyte formation. These processes are necessary and important during gametogenesis. Also, histone modification and X-chromosome inactivation have important roles during germ cell development. Recently, several studies have reported that functional sperm or oocytes can be derived from stem cells in vivo or in vitro. To produce functional germ cells, induction of germ cells from stem cells must recapitulate these processes similar to endogenous germ cells, such as epigenetic modifications. This review focuses on the epigenetic regulation during the process of germ cell development and discusses their importance during the differentiation from stem cells to germ cells.

  1. Epigenetic regulation during the differentiation of stem cells to germ cells

    PubMed Central

    Ge, Wei; Cheng, Shun-Feng; Dyce, Paul W.; Shen, Wei

    2017-01-01

    Gametogenesis is an essential process to ensure the transfer of genetic information from one generation to the next. It also provides a mechanism by which genetic evolution can take place. Although the genome of primordial germ cells (PGCs) is exactly the same with somatic cells within an organism, there are significant differences between their developments. For example, PGCs eventually undergo meiosis to become functional haploid gametes, and prior to that they undergo epigenetic imprinting which greatly alter their genetic regulation. Epigenetic imprinting of PGCs involves the erasure of DNA methylation and the reestablishment of them during sperm and oocyte formation. These processes are necessary and important during gametogenesis. Also, histone modification and X-chromosome inactivation have important roles during germ cell development. Recently, several studies have reported that functional sperm or oocytes can be derived from stem cells in vivo or in vitro. To produce functional germ cells, induction of germ cells from stem cells must recapitulate these processes similar to endogenous germ cells, such as epigenetic modifications. This review focuses on the epigenetic regulation during the process of germ cell development and discusses their importance during the differentiation from stem cells to germ cells. PMID:28915715

  2. Control of plant stem cell function by conserved interacting transcriptional regulators

    PubMed Central

    Zhou, Yun; Liu, Xing; Engstrom, Eric M.; Nimchuk, Zachary L.; Pruneda-Paz, Jose L.; Tarr, Paul T.; Yan, An; Kay, Steve A.; Meyerowitz, Elliot M.

    2014-01-01

    SUMMARY Plant stem cells in the shoot apical meristem (SAM) and root apical meristem (RAM) provide for postembryonic development of above-ground tissues and roots, respectively, while secondary vascular stem cells sustain vascular development1–4. WUSCHEL (WUS), a homeodomain transcription factor expressed in the rib meristem of the SAM, is a key regulatory factor controlling stem cell populations in the Arabidopsis SAM5–6 and is thought to establish the shoot stem cell niche via a feedback circuit with the CLAVATA3 (CLV3) peptide signaling pathway7. WUSCHEL-RELATED HOMEOBOX5 (WOX5), specifically expressed in root quiescent center (QC), defines QC identity and functions interchangeably with WUS in control of shoot and root stem cell niches8. WOX4, expressed in Arabidopsis procambial cells, defines the vascular stem cell niche9–11. WUS/WOX family proteins are evolutionarily and functionally conserved throughout the plant kingdom12 and emerge as key actors in the specification and maintenance of stem cells within all meristems13. However, the nature of the genetic regime in stem cell niches that centers on WOX gene function has been elusive, and molecular links underlying conserved WUS/WOX function in stem cell niches remain unknown. Here we demonstrate that the Arabidopsis HAIRY MERISTEM (HAM)family transcription regulators act as conserved interacting co-factors with WUS/WOX proteins. HAM and WUS share common targets in vivo and their physical interaction is important in driving downstream transcriptional programs and in promoting shoot stem cell proliferation. Differences in the overlapping expression patterns of WOX and HAM family members underlie the formation of diverse stem cell niche locations, and the HAM family is essential for all of these stem cell niches. These findings establish a new framework for the control of stem cell production during plant development. PMID:25363783

  3. Notch receptor regulation of intestinal stem cell homeostasis and crypt regeneration

    PubMed Central

    Carulli, Alexis J.; Keeley, Theresa M.; Demitrack, Elise S.; Chung, Jooho; Maillard, Ivan; Samuelson, Linda C.

    2015-01-01

    The Notch signaling pathway regulates intestinal epithelial cell homeostasis, including stem cell maintenance, progenitor cell proliferation and differentiation. Notch1 and Notch2 receptors are expressed in the epithelium, but individual contributions to these functions are unclear. We used genetic deletion to define receptor roles on stem cell function, cell proliferation/differentiation, and repair after injury. Loss of Notch1 induced a transient secretory cell hyperplasia that spontaneously resolved over time. In contrast, deletion of Notch2 had no secretory cell effect. Compound deletions of Notch1 and Notch2 resulted in a more severe secretory cell hyperplasia than deletion of Notch1 alone. Furthermore, only double deletion of Notch1 and Notch2 decreased cell proliferation, suggesting a low threshold for maintenance of proliferation compared to differentiation. Stem cells were affected by deletion of Notch1, with reduced expression of Olfm4 and fewer LGR5+ stem cells. Deletion of Notch2 had no apparent affect on stem cell homeostasis. However, we observed impaired crypt regeneration after radiation in both Notch1- and Notch2-deleted intestine, suggesting that higher Notch activity is required post-injury. These findings suggest that Notch1 is the primary receptor regulating intestinal stem cell function and that Notch1 and Notch2 together regulate epithelial cell proliferation, cell fate determination, and post-injury regeneration. PMID:25835502

  4. Periodontal Ligament Stem Cells Regulate Apoptosis of Neutrophils

    PubMed Central

    Wang, Qing; Ding, Gang; Xu, Xin

    2017-01-01

    Abstract Periodontal ligament stem cells (PDLSCs) are promising cell resource for the cell-based therapy for periodontitis and regeneration of bio-root. In this study, we investigated the effect of PDLSCs on neutrophil, a critical constituent of innate immunity, and the underlying mechanisms. The effect of PDLSCs on the proliferation and apoptosis of resting neutrophils and IL-8 activated neutrophils was tested under cell-cell contact culture and Transwell culture, with or without anti-IL-6 neutralizing antibody. We found that PDLSCs could promote the proliferation and reduce the apoptosis of neutrophils whether under cell-cell contact or Transwell culture. Anti-IL-6 antibody reduced PDLSCs-mediated inhibition of neutrophil apoptosis. IL-6 at the concentration of 10ng/ml and 20ng/ml could inhibit neutrophil apoptosis statistically. Collectively, PDLSCs could reduce the apoptosis of neutrophils via IL-6.

  5. The role of CD44 in fetal and adult hematopoietic stem cell regulation.

    PubMed

    Cao, Huimin; Heazlewood, Shen Y; Williams, Brenda; Cardozo, Daniela; Nigro, Julie; Oteiza, Ana; Nilsson, Susan K

    2016-01-01

    Throughout development, hematopoietic stem cells migrate to specific microenvironments, where their fate is, in part, extrinsically controlled. CD44 standard as a member of the cell adhesion molecule family is extensively expressed within adult bone marrow and has been previously reported to play important roles in adult hematopoietic regulation via CD44 standard-ligand interactions. In this manuscript, CD44 expression and function are further assessed and characterized on both fetal and adult hematopoietic stem cells. Using a CD44(-/-) mouse model, conserved functional roles of CD44 are revealed throughout development. CD44 is critical in the maintenance of hematopoietic stem and progenitor pools, as well as in hematopoietic stem cell migration. CD44 expression on hematopoietic stem cells as well as other hematopoietic cells within the bone marrow microenvironment is important in the homing and lodgment of adult hematopoietic stem cells isolated from the bone/bone marrow interface. CD44 is also involved in fetal hematopoietic stem cell migration out of the liver, via a process involving stromal cell-derived factor-1α. The absence of CD44 in neonatal bone marrow has no impact on the size of the long-term reconstituting hematopoietic stem cell pool, but results in an enhanced long-term engraftment potential of hematopoietic stem cells.

  6. The role of CD44 in fetal and adult hematopoietic stem cell regulation

    PubMed Central

    Cao, Huimin; Heazlewood, Shen Y.; Williams, Brenda; Cardozo, Daniela; Nigro, Julie; Oteiza, Ana; Nilsson, Susan K.

    2016-01-01

    Throughout development, hematopoietic stem cells migrate to specific microenvironments, where their fate is, in part, extrinsically controlled. CD44 standard as a member of the cell adhesion molecule family is extensively expressed within adult bone marrow and has been previously reported to play important roles in adult hematopoietic regulation via CD44 standard-ligand interactions. In this manuscript, CD44 expression and function are further assessed and characterized on both fetal and adult hematopoietic stem cells. Using a CD44−/− mouse model, conserved functional roles of CD44 are revealed throughout development. CD44 is critical in the maintenance of hematopoietic stem and progenitor pools, as well as in hematopoietic stem cell migration. CD44 expression on hematopoietic stem cells as well as other hematopoietic cells within the bone marrow microenvironment is important in the homing and lodgment of adult hematopoietic stem cells isolated from the bone/bone marrow interface. CD44 is also involved in fetal hematopoietic stem cell migration out of the liver, via a process involving stromal cell-derived factor-1α. The absence of CD44 in neonatal bone marrow has no impact on the size of the long-term reconstituting hematopoietic stem cell pool, but results in an enhanced long-term engraftment potential of hematopoietic stem cells. PMID:26546504

  7. Perturbation-Expression Analysis Identifies RUNX1 as a Regulator of Human Mammary Stem Cell Differentiation

    PubMed Central

    Sokol, Ethan S.; Miller, Daniel H.; Mathis, Robert A.; Gupta, Piyush B.

    2015-01-01

    The search for genes that regulate stem cell self-renewal and differentiation has been hindered by a paucity of markers that uniquely label stem cells and early progenitors. To circumvent this difficulty we have developed a method that identifies cell-state regulators without requiring any markers of differentiation, termed Perturbation-Expression Analysis of Cell States (PEACS). We have applied this marker-free approach to screen for transcription factors that regulate mammary stem cell differentiation in a 3D model of tissue morphogenesis and identified RUNX1 as a stem cell regulator. Inhibition of RUNX1 expanded bipotent stem cells and blocked their differentiation into ductal and lobular tissue rudiments. Reactivation of RUNX1 allowed exit from the bipotent state and subsequent differentiation and mammary morphogenesis. Collectively, our findings show that RUNX1 is required for mammary stem cells to exit a bipotent state, and provide a new method for discovering cell-state regulators when markers are not available. PMID:25894653

  8. Regulation of nonsmall-cell lung cancer stem cell like cells by neurotransmitters and opioid peptides.

    PubMed

    Banerjee, Jheelam; Papu John, Arokya M S; Schuller, Hildegard M

    2015-12-15

    Nonsmall-cell lung cancer (NSCLC) is the leading type of lung cancer and has a poor prognosis. We have shown that chronic stress promoted NSCLC xenografts in mice via stress neurotransmitter-activated cAMP signaling downstream of beta-adrenergic receptors and incidental beta-blocker therapy was reported to improve clinical outcomes in NSCLC patients. These findings suggest that psychological stress promotes NSCLC whereas pharmacologically or psychologically induced decreases in cAMP may inhibit NSCLC. Cancer stem cells are thought to drive the development, progression and resistance to therapy of NSCLC. However, their potential regulation by stress neurotransmitters has not been investigated. In the current study, epinephrine increased the number of cancer stem cell like cells (CSCs) from three NSCLC cell lines in spheroid formation assays while enhancing intracellular cAMP and the stem cell markers sonic hedgehog (SHH), aldehyde dehydrogenase-1 (ALDH-1) and Gli1, effects reversed by GABA or dynorphin B via Gαi -mediated inhibition of cAMP formation. The growth of NSCLC xenografts in a mouse model of stress reduction was significantly reduced as compared with mice maintained under standard conditions. Stress reduction reduced serum levels of corticosterone, norepinephrine and epinephrine while the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and opioid peptides increased. Stress reduction significantly reduced cAMP, VEGF, p-ERK, p-AKT, p-CREB, p-SRc, SHH, ALDH-1 and Gli1 in xenograft tissues whereas cleaved caspase-3 and p53 were induced. We conclude that stress neurotransmitters activate CSCs in NSCLC via multiple cAMP-mediated pathways and that pharmacologically or psychologically induced decreases in cAMP signaling may improve clinical outcomes in NSCLC patients.

  9. Β-carotene inhibits neuroblastoma tumorigenesis by regulating cell differentiation and cancer cell stemness.

    PubMed

    Lim, Ji Ye; Kim, Yoo-Sun; Kim, Kyung-Mi; Min, Soo Jin; Kim, Yuri

    2014-08-08

    Neuroblastoma (NB) is the most common extracranial solid cancer in young children and malignant NB cells have been shown to possess cancer stem cell (CSC) characteristics. Thus, the successful elimination of CSCs represents a strategy for developing an effective preventive and chemotherapeutic agent. CSCs are characterized by differentiation and tumorigenicity. β-Carotene (BC) has been associated with many anticancer mechanisms, although the efficacy of BC on CSCs remains unclear. In the present study, the effects of BC on tumor cell differentiation and tumorigenicity was investigated using a xenograft model. Mice were pretreated with BC for 21 days, then received a subcutaneous injection of SK-N-BE(2)C cells. Both tumor incidence and tumor growth were significantly inhibited for mice that received BC supplementation compared to the control group. Treatment with BC has also been shown to induce tumor cell differentiation by up-regulating differentiation markers, such as vimentin, peripherin, and neurofilament. Conversely, BC treatment has been shown to significantly suppress tumor stemness by down-regulating CSC markers such as Oct 3/4 and DLK1. BC treatment also significantly down-regulated HIF1-α expression and its downstream target, vascular endothelial growth factor (VEGF). Taken together, these results suggest that BC is a potential chemotherapeutic reagent for the treatment of NB, and mediates this effect by regulating the differentiation and stemness of CSCs, respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. SETD7 Regulates the Differentiation of Human Embryonic Stem Cells

    PubMed Central

    Castaño, Julio; Morera, Cristina; Sesé, Borja; Boue, Stephanie; Bonet-Costa, Carles; Martí, Merce; Roque, Alicia; Jordan, Albert; Barrero, Maria J.

    2016-01-01

    The successful use of specialized cells in regenerative medicine requires an optimization in the differentiation protocols that are currently used. Understanding the molecular events that take place during the differentiation of human pluripotent cells is essential for the improvement of these protocols and the generation of high quality differentiated cells. In an effort to understand the molecular mechanisms that govern differentiation we identify the methyltransferase SETD7 as highly induced during the differentiation of human embryonic stem cells and differentially expressed between induced pluripotent cells and somatic cells. Knock-down of SETD7 causes differentiation defects in human embryonic stem cell including delay in both the silencing of pluripotency-related genes and the induction of differentiation genes. We show that SETD7 methylates linker histone H1 in vitro causing conformational changes in H1. These effects correlate with a decrease in the recruitment of H1 to the pluripotency genes OCT4 and NANOG during differentiation in the SETD7 knock down that might affect the proper silencing of these genes during differentiation. PMID:26890252

  11. miRNA-regulated cancer stem cells: understanding the property and the role of miRNA in carcinogenesis.

    PubMed

    Chakraborty, Chiranjib; Chin, Kok-Yong; Das, Srijit

    2016-10-01

    Over the last few years, microRNAs (miRNA)-controlled cancer stem cells have drawn enormous attention. Cancer stem cells are a small population of tumor cells that possess the stem cell property of self-renewal. Recent data shows that miRNA regulates this small population of stem cells. In the present review, we explained different characteristics of cancer stem cells as well as miRNA regulation of self-renewal and differentiation in cancer stem cells. We also described the migration and tumor formation. Finally, we described the different miRNAs that regulate various types of cancer stem cells, such as prostate cancer stem cells, head and neck cancer stem cells, breast cancer stem cells, colorectal cancer stem cells, lung cancer stem cells, gastric cancer stem cells, pancreatic cancer stem cells, etc. Extensive research is needed in order to employ miRNA-based therapeutics to control cancer stem cell population in various cancers in the future.

  12. Single-cell expression profiling of human epidermal stem and transit-amplifying cells: Lrig1 is a regulator of stem cell quiescence

    PubMed Central

    Jensen, Kim B.; Watt, Fiona M.

    2006-01-01

    Considerable progress has been made in characterizing epidermal stem cells by microarray analysis of FACS-selected populations. One limitation of this approach is that the gene expression profiles represent the average of the cell population, potentially masking cellular heterogeneity of functional significance. To overcome this problem, we have performed single-cell expression profiling. We have generated cDNA libraries from single human epidermal cells, designated as stem or transit-amplifying cells on the basis of Delta1 and melanoma-associated chondroitin sulfate proteoglycan expression. Of the 14 putative stem cell markers identified, we selected one, the EGF receptor antagonist leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), for further study. Lrig1 was expressed in groups of basal cells in human interfollicular epidermis previously identified as enriched for stem cells. Overexpression of Lrig1 decreased keratinocyte proliferation but did not affect the proportion of stem and transit-amplifying cells, as judged by clonal growth characteristics. Down-regulation of Lrig1 using siRNA increased cell-surface EGF receptor levels, enhanced activation of downstream pathways, and stimulated proliferation. Lrig1 acted in part by negatively regulating the Myc promoter. We propose that Lrig1 maintains epidermal stem cells in a quiescent nondividing state, and that Lrig1 down-regulation triggers proliferation. PMID:16877544

  13. Single-cell expression profiling of human epidermal stem and transit-amplifying cells: Lrig1 is a regulator of stem cell quiescence.

    PubMed

    Jensen, Kim B; Watt, Fiona M

    2006-08-08

    Considerable progress has been made in characterizing epidermal stem cells by microarray analysis of FACS-selected populations. One limitation of this approach is that the gene expression profiles represent the average of the cell population, potentially masking cellular heterogeneity of functional significance. To overcome this problem, we have performed single-cell expression profiling. We have generated cDNA libraries from single human epidermal cells, designated as stem or transit-amplifying cells on the basis of Delta1 and melanoma-associated chondroitin sulfate proteoglycan expression. Of the 14 putative stem cell markers identified, we selected one, the EGF receptor antagonist leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), for further study. Lrig1 was expressed in groups of basal cells in human interfollicular epidermis previously identified as enriched for stem cells. Overexpression of Lrig1 decreased keratinocyte proliferation but did not affect the proportion of stem and transit-amplifying cells, as judged by clonal growth characteristics. Down-regulation of Lrig1 using siRNA increased cell-surface EGF receptor levels, enhanced activation of downstream pathways, and stimulated proliferation. Lrig1 acted in part by negatively regulating the Myc promoter. We propose that Lrig1 maintains epidermal stem cells in a quiescent nondividing state, and that Lrig1 down-regulation triggers proliferation.

  14. Epidermal Development in Mammals: Key Regulators, Signals from Beneath, and Stem Cells

    PubMed Central

    Liu, Shuang; Zhang, Huishan; Duan, Enkui

    2013-01-01

    Epidermis is one of the best-studied tissues in mammals that contain types of stem cells. Outstanding works in recent years have shed great light on behaviors of different epidermal stem cell populations in the homeostasis and regeneration of the epidermis as well as hair follicles. Also, the molecular mechanisms governing these stem cells are being elucidated, from genetic to epigenetic levels. Compared with the explicit knowledge about adult skin, embryonic development of the epidermis, especially the early period, still needs exploration. Furthermore, stem cells in the embryonic epidermis are largely unstudied or ambiguously depicted. In this review, we will summarize and discuss the process of embryonic epidermal development, with focuses on some key molecular regulators and the role of the sub-epidermal mesenchyme. We will also try to trace adult epidermal stem cell populations back to embryonic development. In addition, we will comment on in vitro derivation of epidermal lineages from ES cells and iPS cells. PMID:23708093

  15. Redox Regulation of Stem/Progenitor Cells and Bone Marrow Niche

    PubMed Central

    Urao, Norifumi; Ushio-Fukai, Masuko

    2013-01-01

    Bone marrow (BM)-derived stem and progenitor cell functions including self-renewal, differentiation, survival, migration, proliferation and mobilization are regulated by unique cell-intrinsic signals and -extrinsic signals provided by their microenvironment, also termed the ‘niche’. Reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), play important roles in regulating stem and progenitor cell function in various physiologic and pathologic responses. The low level of H2O2 in quiescent hematopoietic stem cells (HSCs) contributes to maintain their stemness, whereas a higher level of H2O2 within HSCs or their niche promotes differentiation, proliferation, migration, and survival of HSCs or stem/progenitor cells. Major sources of ROS are NADPH oxidase and mitochondria. In response to ischemic injury, ROS derived from NADPH oxidase are increased in the BM microenvironment, which is required for hypoxia and HIF1α expression and expansion throughout the BM. This, in turn, promotes progenitor cell expansion and mobilization from BM, leading to reparative neovascularization and tissue repair. In pathophysiological states such as aging, atherosclerosis, heart failure, hypertension and diabetes, excess amounts of ROS create an inflammatory and oxidative microenvironment, which induces cell damage and apoptosis of stem and progenitor cells. Understanding the molecular mechanisms of how ROS regulate the functions of stem and progenitor cells and their niche in physiological and pathological conditions will lead to the development of novel therapeutic strategies. PMID:23085514

  16. Epigenetic regulation of neural stem cell fate during corticogenesis.

    PubMed

    MuhChyi, Chai; Juliandi, Berry; Matsuda, Taito; Nakashima, Kinichi

    2013-10-01

    The cerebral cortex comprises over three quarters of the brain, and serves as structural basis for the sophisticated perceptual and cognitive functions. It develops from common multipotent neural stem cells (NSCs) that line the neural tube. Development of the NSCs encompasses sequential phases of progenitor expansion, neurogenesis, and gliogenesis along with the progression of developmental stages. Interestingly, NSCs steadfastly march through all of these phases and give rise to specific neural cell types in a temporally defined and highly predictable manner. Herein, we delineate the intrinsic and extrinsic factors that dictate the progression and tempo of NSC differentiation during cerebral cortex development, and how epigenetic modifications contribute to the dynamic properties of NSCs.

  17. JNK contributes to temozolomide resistance of stem-like glioblastoma cells via regulation of MGMT expression.

    PubMed

    Okada, Masashi; Sato, Atsushi; Shibuya, Keita; Watanabe, Eriko; Seino, Shizuka; Suzuki, Shuhei; Seino, Manabu; Narita, Yoshitaka; Shibui, Soichiro; Kayama, Takamasa; Kitanaka, Chifumi

    2014-02-01

    While elimination of the cancer stem cell population is increasingly recognized as a key to successful treatment of cancer, the high resistance of cancer stem cells to conventional chemoradiotherapy remains a therapeutic challenge. O6-methylguanine DNA methyltransferase (MGMT), which is frequently expressed in cancer stem cells of glioblastoma, has been implicated in their resistance to temozolomide, the first-line chemotherapeutic agent against newly diagnosed glioblastoma. However, much remains unknown about the molecular regulation that underlies MGMT expression and temozolomide resistance of glioblastoma cancer stem cells. Here, we identified JNK as a novel player in the control of MGMT expression and temozolomide resistance of glioblastoma cancer stem cells. We showed that inhibition of JNK, either pharmacologically or by RNA interference, in stem-like glioblastoma cells derived directly from glioblastoma tissues reduces their MGMT expression and temozolomide resistance. Importantly, sensitization of stem-like glioblastoma cells to temozolomide by JNK inhibition was dependent on MGMT expression, implying that JNK controls temozolomide resistance of stem-like glioblastoma cells through MGMT expression. Our findings suggest that concurrent use of JNK inhibitors with temozolomide may be a rational therapeutic approach to effectively target the cancer stem cell population in the treatment of glioblastoma.

  18. Regulation of stem cell plasticity: mechanisms and relevance to tissue biology and cancer.

    PubMed

    Strauss, Robert; Hamerlik, Petra; Lieber, André; Bartek, Jiri

    2012-05-01

    Embryonic stem cells (ESCs) are associated with a high degree of plasticity, which allows them to self-renew and differentiate into every somatic cell. During differentiation, ESCs follow a hierarchically organized pattern towards tissue specificity, which ultimately results in permanent cell cycle arrest and a loss of cellular plasticity. In contrast to their normal somatic counterparts, cancer cells retain elevated levels of plasticity that include switches between epithelial and mesenchymal phenotypes. Transitions between these cell stages have lately been linked to the reacquisition of stem cell features during cellular reprogramming and dedifferentiation in normal and neoplastic cells. In this review, we discuss the key factors and their interplay that is needed to regain a stem cell stage with a particular emphasis put on the impact of cell cycle regulation. Apart from mechanistic insights into the emerging fundamental processes of stem cell plasticity and capacity to transdifferentiate, we also highlight implications of these concepts for tissue biology, tumorigenesis, and cancer therapy.

  19. Stem cells.

    PubMed

    Behr, Björn; Ko, Sae Hee; Wong, Victor W; Gurtner, Geoffrey C; Longaker, Michael T

    2010-10-01

    Stem cells are self-renewing cells capable of differentiating into multiple cell lines and are classified according to their origin and their ability to differentiate. Enormous potential exists in use of stem cells for regenerative medicine. To produce effective stem cell-based treatments for a range of diseases, an improved understanding of stem cell biology and better control over stem cell fate are necessary. In addition, the barriers to clinical translation, such as potential oncologic properties of stem cells, need to be addressed. With renewed government support and continued refinement of current stem cell methodologies, the future of stem cell research is exciting and promises to provide novel reconstructive options for patients and surgeons limited by traditional paradigms.

  20. Types of Stem Cells

    MedlinePlus

    ... Stem Cell Glossary Search Toggle Nav Types of Stem Cells Stem cells are the foundation from which all ... Learn About Stem Cells > Types of Stem Cells Stem cells Stem cells are the foundation for every organ ...

  1. The stem cell/cancer stem cell marker ALDH1A3 regulates the expression of the survival factor tissue transglutaminase, in mesenchymal glioma stem cells

    PubMed Central

    Sullivan, Kelly E.; Rojas, Kathy; Cerione, Richard A.; Nakano, Ichiro; Wilson, Kristin F.

    2017-01-01

    Tissue transglutaminase (tTG), a dual-function enzyme with GTP-binding and acyltransferase activities, has been implicated in the survival and chemotherapy resistance of aggressive cancer cells and cancer stem cells, including glioma stem cells (GSCs). Using a model system comprising two distinct subtypes of GSCs referred to as proneural (PN) and mesenchymal (MES), we find that the phenotypically aggressive and radiation therapy-resistant MES GSCs exclusively express tTG relative to PN GSCs. As such, the self-renewal, proliferation, and survival of these cells was sensitive to treatment with tTG inhibitors, with a benefit being observed when combined with the standard of care for high grade gliomas (i.e. radiation or temozolomide). Efforts to understand the molecular drivers of tTG expression in MES GSCs revealed an unexpected link between tTG and a common marker for stem cells and cancer stem cells, Aldehyde dehydrogenase 1A3 (ALDH1A3). ALDH1A3, as well as other members of the ALDH1 subfamily, can function in cells as a retinaldehyde dehydrogenase to generate retinoic acid (RA) from retinal. We show that the enzymatic activity of ALDH1A3 and its product, RA, are necessary for the observed expression of tTG in MES GSCs. Additionally, the ectopic expression of ALDH1A3 in PN GSCs is sufficient to induce the expression of tTG in these cells, further demonstrating a causal link between ALDH1A3 and tTG. Together, these findings ascribe a novel function for ALDH1A3 in an aggressive GSC phenotype via the up-regulation of tTG, and suggest the potential for a similar role by ALDH1 family members across cancer types. PMID:28423611

  2. The stem cell/cancer stem cell marker ALDH1A3 regulates the expression of the survival factor tissue transglutaminase, in mesenchymal glioma stem cells.

    PubMed

    Sullivan, Kelly E; Rojas, Kathy; Cerione, Richard A; Nakano, Ichiro; Wilson, Kristin F

    2017-04-04

    Tissue transglutaminase (tTG), a dual-function enzyme with GTP-binding and acyltransferase activities, has been implicated in the survival and chemotherapy resistance of aggressive cancer cells and cancer stem cells, including glioma stem cells (GSCs). Using a model system comprising two distinct subtypes of GSCs referred to as proneural (PN) and mesenchymal (MES), we find that the phenotypically aggressive and radiation therapy-resistant MES GSCs exclusively express tTG relative to PN GSCs. As such, the self-renewal, proliferation, and survival of these cells was sensitive to treatment with tTG inhibitors, with a benefit being observed when combined with the standard of care for high grade gliomas (i.e. radiation or temozolomide). Efforts to understand the molecular drivers of tTG expression in MES GSCs revealed an unexpected link between tTG and a common marker for stem cells and cancer stem cells, Aldehyde dehydrogenase 1A3 (ALDH1A3). ALDH1A3, as well as other members of the ALDH1 subfamily, can function in cells as a retinaldehyde dehydrogenase to generate retinoic acid (RA) from retinal. We show that the enzymatic activity of ALDH1A3 and its product, RA, are necessary for the observed expression of tTG in MES GSCs. Additionally, the ectopic expression of ALDH1A3 in PN GSCs is sufficient to induce the expression of tTG in these cells, further demonstrating a causal link between ALDH1A3 and tTG. Together, these findings ascribe a novel function for ALDH1A3 in an aggressive GSC phenotype via the up-regulation of tTG, and suggest the potential for a similar role by ALDH1 family members across cancer types.

  3. Identification and molecular regulation of neural stem cells in the olfactory epithelium.

    PubMed

    Beites, Crestina L; Kawauchi, Shimako; Crocker, Candice E; Calof, Anne L

    2005-06-10

    The sensory neurons that subserve olfaction, olfactory receptor neurons (ORNs), are regenerated throughout life, making the neuroepithelium in which they reside [the olfactory epithelium (OE)] an excellent model for studying how intrinsic and extrinsic factors regulate stem cell dynamics and neurogenesis during development and regeneration. Numerous studies indicate that transcription factors and signaling molecules together regulate generation of ORNs from stem and progenitor cells during development, and work on regenerative neurogenesis indicates that these same factors may operate at postnatal ages as well. This review describes our current knowledge of the identity of the OE neural stem cell; the different cell types that are thought to be the progeny (directly or indirectly) of this stem cell; and the factors that influence cell differentiation in the OE neuronal lineage. We review data suggesting that (1) the ORN lineage contains three distinct proliferating cell types--a stem cell and two populations of transit amplifying cells; (2) in established OE, these three cell types are present within the basal cell compartment of the epithelium; and (3) the stem cell that gives rise ultimately to ORNs may also generate two glial cell types of the primary olfactory pathway: sustentacular cells (SUS), which lie within OE proper; and olfactory ensheathing cells (OEC), which envelope the olfactory nerve. In addition, we describe factors that are both made by and found within the microenvironment of OE stem and progenitor cells, and which exert crucial growth regulatory effects on these cells. Thus, as with other regenerating tissues, the basis of regeneration in the OE appears be a population of stem cells, which resides within a microenvironment (niche) consisting of factors crucial for maintenance of its capacity for proliferation and differentiation.

  4. Identification and molecular regulation of neural stem cells in the olfactory epithelium

    SciTech Connect

    Beites, Crestina L.; Kawauchi, Shimako; Crocker, Candice E.; Calof, Anne L. . E-mail: alcalof@uci.edu

    2005-06-10

    The sensory neurons that subserve olfaction, olfactory receptor neurons (ORNs), are regenerated throughout life, making the neuroepithelium in which they reside [the olfactory epithelium (OE)] an excellent model for studying how intrinsic and extrinsic factors regulate stem cell dynamics and neurogenesis during development and regeneration. Numerous studies indicate that transcription factors and signaling molecules together regulate generation of ORNs from stem and progenitor cells during development, and work on regenerative neurogenesis indicates that these same factors may operate at postnatal ages as well. This review describes our current knowledge of the identity of the OE neural stem cell; the different cell types that are thought to be the progeny (directly or indirectly) of this stem cell; and the factors that influence cell differentiation in the OE neuronal lineage. We review data suggesting that (1) the ORN lineage contains three distinct proliferating cell types-a stem cell and two populations of transit amplifying cells; (2) in established OE, these three cell types are present within the basal cell compartment of the epithelium; and (3) the stem cell that gives rise ultimately to ORNs may also generate two glial cell types of the primary olfactory pathway: sustentacular cells (SUS), which lie within OE proper; and olfactory ensheathing cells (OEC), which envelope the olfactory nerve. In addition, we describe factors that are both made by and found within the microenvironment of OE stem and progenitor cells, and which exert crucial growth regulatory effects on these cells. Thus, as with other regenerating tissues, the basis of regeneration in the OE appears be a population of stem cells, which resides within a microenvironment (niche) consisting of factors crucial for maintenance of its capacity for proliferation and differentiation.

  5. Lin28: Primal Regulator of Growth and Metabolism in Stem Cells

    PubMed Central

    Shyh-Chang, Ng; Daley, George Q.

    2013-01-01

    In recent years, the highly conserved Lin28 RNA-binding proteins have emerged as factors that define stemness in several tissue lineages. Lin28 proteins repress let-7 microRNAs and influence mRNA translation, thereby regulating the self-renewal of mammalian embryonic stem cells. Subsequent discoveries revealed that Lin28a and Lin28b are also important in organismal growth and metabolism, tissue development, somatic reprogramming and cancer. In this Review, we discuss the Lin28 pathway and its regulation, outline its roles in stem cells, tissue development, and pathogenesis, and examine the ramifications for re-engineering mammalian physiology. PMID:23561442

  6. Retroviral Transcriptional Regulation and Embryonic Stem Cells: War and Peace

    PubMed Central

    Schlesinger, Sharon

    2014-01-01

    Retroviruses have evolved complex transcriptional enhancers and promoters that allow their replication in a wide range of tissue and cell types. Embryonic stem (ES) cells, however, characteristically suppress transcription of proviruses formed after infection by exogenous retroviruses and also of most members of the vast array of endogenous retroviruses in the genome. These cells have unusual profiles of transcribed genes and are poised to make rapid changes in those profiles upon induction of differentiation. Many of the transcription factors in ES cells control both host and retroviral genes coordinately, such that retroviral expression patterns can serve as markers of ES cell pluripotency. This overlap is not coincidental; retrovirus-derived regulatory sequences are often used to control cellular genes important for pluripotency. These sequences specify the temporal control and perhaps “noisy” control of cellular genes that direct proper cell gene expression in primitive cells and their differentiating progeny. The evidence suggests that the viral elements have been domesticated for host needs, reflecting the wide-ranging exploitation of any and all available DNA sequences in assembling regulatory networks. PMID:25547290

  7. Retroviral transcriptional regulation and embryonic stem cells: war and peace.

    PubMed

    Schlesinger, Sharon; Goff, Stephen P

    2015-03-01

    Retroviruses have evolved complex transcriptional enhancers and promoters that allow their replication in a wide range of tissue and cell types. Embryonic stem (ES) cells, however, characteristically suppress transcription of proviruses formed after infection by exogenous retroviruses and also of most members of the vast array of endogenous retroviruses in the genome. These cells have unusual profiles of transcribed genes and are poised to make rapid changes in those profiles upon induction of differentiation. Many of the transcription factors in ES cells control both host and retroviral genes coordinately, such that retroviral expression patterns can serve as markers of ES cell pluripotency. This overlap is not coincidental; retrovirus-derived regulatory sequences are often used to control cellular genes important for pluripotency. These sequences specify the temporal control and perhaps "noisy" control of cellular genes that direct proper cell gene expression in primitive cells and their differentiating progeny. The evidence suggests that the viral elements have been domesticated for host needs, reflecting the wide-ranging exploitation of any and all available DNA sequences in assembling regulatory networks.

  8. Regulation of hematopoietic stem cell differentiation by a single ubiquitin ligase-substrate complex.

    PubMed

    Reavie, Linsey; Della Gatta, Giusy; Crusio, Kelly; Aranda-Orgilles, Beatriz; Buckley, Shannon M; Thompson, Benjamin; Lee, Eugine; Gao, Jie; Bredemeyer, Andrea L; Helmink, Beth A; Zavadil, Jiri; Sleckman, Barry P; Palomero, Teresa; Ferrando, Adolfo; Aifantis, Iannis

    2010-03-01

    Hematopoietic stem cell (HSC) differentiation is regulated by cell-intrinsic and cell-extrinsic cues. In addition to transcriptional regulation, post-translational regulation may also control HSC differentiation. To test this hypothesis, we visualized the ubiquitin-regulated protein stability of a single transcription factor, c-Myc. The stability of c-Myc protein was indicative of HSC quiescence, and c-Myc protein abundance was controlled by the ubiquitin ligase Fbw7. Fine changes in the stability of c-Myc protein regulated the HSC gene-expression signature. Using whole-genome genomic approaches, we identified specific regulators of HSC function directly controlled by c-Myc binding; however, adult HSCs and embryonic stem cells sensed and interpreted c-Myc-regulated gene expression in distinct ways. Our studies show that a ubiquitin ligase-substrate pair can orchestrate the molecular program of HSC differentiation.

  9. Surface topography regulates wnt signaling through control of primary cilia structure in mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    McMurray, R. J.; Wann, A. K. T.; Thompson, C. L.; Connelly, J. T.; Knight, M. M.

    2013-12-01

    The primary cilium regulates cellular signalling including influencing wnt sensitivity by sequestering β-catenin within the ciliary compartment. Topographic regulation of intracellular actin-myosin tension can control stem cell fate of which wnt is an important mediator. We hypothesized that topography influences mesenchymal stem cell (MSC) wnt signaling through the regulation of primary cilia structure and function. MSCs cultured on grooves expressed elongated primary cilia, through reduced actin organization. siRNA inhibition of anterograde intraflagellar transport (IFT88) reduced cilia length and increased active nuclear β-catenin. Conversely, increased primary cilia assembly in MSCs cultured on the grooves was associated with decreased levels of nuclear active β-catenin, axin-2 induction and proliferation, in response to wnt3a. This negative regulation, on grooved topography, was reversed by siRNA to IFT88. This indicates that subtle regulation of IFT and associated cilia structure, tunes the wnt response controlling stem cell differentiation.

  10. Surface topography regulates wnt signaling through control of primary cilia structure in mesenchymal stem cells.

    PubMed

    McMurray, R J; Wann, A K T; Thompson, C L; Connelly, J T; Knight, M M

    2013-12-18

    The primary cilium regulates cellular signalling including influencing wnt sensitivity by sequestering β-catenin within the ciliary compartment. Topographic regulation of intracellular actin-myosin tension can control stem cell fate of which wnt is an important mediator. We hypothesized that topography influences mesenchymal stem cell (MSC) wnt signaling through the regulation of primary cilia structure and function. MSCs cultured on grooves expressed elongated primary cilia, through reduced actin organization. siRNA inhibition of anterograde intraflagellar transport (IFT88) reduced cilia length and increased active nuclear β-catenin. Conversely, increased primary cilia assembly in MSCs cultured on the grooves was associated with decreased levels of nuclear active β-catenin, axin-2 induction and proliferation, in response to wnt3a. This negative regulation, on grooved topography, was reversed by siRNA to IFT88. This indicates that subtle regulation of IFT and associated cilia structure, tunes the wnt response controlling stem cell differentiation.

  11. Set7 mediated interactions regulate transcriptional networks in embryonic stem cells.

    PubMed

    Tuano, Natasha K; Okabe, Jun; Ziemann, Mark; Cooper, Mark E; El-Osta, Assam

    2016-11-02

    Histone methylation by lysine methyltransferase enzymes regulate the expression of genes implicated in lineage specificity and cellular differentiation. While it is known that Set7 catalyzes mono-methylation of histone and non-histone proteins, the functional importance of this enzyme in stem cell differentiation remains poorly understood. We show Set7 expression is increased during mouse embryonic stem cell (mESC) differentiation and is regulated by the pluripotency factors, Oct4 and Sox2. Transcriptional network analyses reveal smooth muscle (SM) associated genes are subject to Set7-mediated regulation. Furthermore, pharmacological inhibition of Set7 activity confirms this regulation. We observe Set7-mediated modification of serum response factor (SRF) and mono-methylation of histone H4 lysine 4 (H3K4me1) regulate gene expression. We conclude the broad substrate specificity of Set7 serves to control key transcriptional networks in embryonic stem cells.

  12. Surface topography regulates wnt signaling through control of primary cilia structure in mesenchymal stem cells

    PubMed Central

    McMurray, R. J.; Wann, A. K. T.; Thompson, C. L.; Connelly, J. T.; Knight, M. M.

    2013-01-01

    The primary cilium regulates cellular signalling including influencing wnt sensitivity by sequestering β-catenin within the ciliary compartment. Topographic regulation of intracellular actin-myosin tension can control stem cell fate of which wnt is an important mediator. We hypothesized that topography influences mesenchymal stem cell (MSC) wnt signaling through the regulation of primary cilia structure and function. MSCs cultured on grooves expressed elongated primary cilia, through reduced actin organization. siRNA inhibition of anterograde intraflagellar transport (IFT88) reduced cilia length and increased active nuclear β-catenin. Conversely, increased primary cilia assembly in MSCs cultured on the grooves was associated with decreased levels of nuclear active β-catenin, axin-2 induction and proliferation, in response to wnt3a. This negative regulation, on grooved topography, was reversed by siRNA to IFT88. This indicates that subtle regulation of IFT and associated cilia structure, tunes the wnt response controlling stem cell differentiation. PMID:24346024

  13. Regulation of Ovarian Cancer Stem Cells or Tumor-Initiating Cells

    PubMed Central

    Kwon, Mi Jeong; Shin, Young Kee

    2013-01-01

    Cancer stem cells or tumor-initiating cells (CSC/TICs), which can undergo self-renewal and differentiation, are thought to play critical roles in tumorigenesis, therapy resistance, tumor recurrence and metastasis. Tumor recurrence and chemoresistance are major causes of poor survival rates of ovarian cancer patients, which may be due in part to the existence of CSC/TICs. Therefore, elucidating the molecular mechanisms responsible for the ovarian CSC/TICs is required to develop a cure for this malignancy. Recent studies have indicated that the properties of CSC/TICs can be regulated by microRNAs, genes and signaling pathways which also function in normal stem cells. Moreover, emerging evidence suggests that the tumor microenvironments surrounding CSC/TICs are crucial for the maintenance of these cells. Similarly, efforts are now being made to unravel the mechanism involved in the regulation of ovarian CSC/TICs, although much work is still needed. This review considers recent advances in identifying the genes and pathways involved in the regulation of ovarian CSC/TICs. Furthermore, current approaches targeting ovarian CSC/TICs are described. Targeting both CSC/TICs and bulk tumor cells is suggested as a more effective approach to eliminating ovarian tumors. Better understanding of the regulation of ovarian CSC/TICs might facilitate the development of improved therapeutic strategies for recurrent ovarian cancer. PMID:23528891

  14. Asymmetric segregation of the tumor suppressor brat regulates self-renewal in Drosophila neural stem cells.

    PubMed

    Betschinger, Joerg; Mechtler, Karl; Knoblich, Juergen A

    2006-03-24

    How stem cells generate both differentiating and self-renewing daughter cells is unclear. Here, we show that Drosophila larval neuroblasts-stem cell-like precursors of the adult brain-regulate proliferation by segregating the growth inhibitor Brat and the transcription factor Prospero into only one daughter cell. Like Prospero, Brat binds and cosegregates with the adaptor protein Miranda. In larval neuroblasts, both Brat and Prospero are required to inhibit self-renewal in one of the two daughter cells. While Prospero regulates cell-cycle gene transcription, Brat acts as a posttranscriptional inhibitor of dMyc. In brat or prospero mutants, both daughter cells grow and behave like neuroblasts leading to the formation of larval brain tumors. Similar defects are seen in lethal giant larvae (lgl) mutants where Brat and Prospero are not asymmetric. We have identified a molecular mechanism that may control self-renewal and prevent tumor formation in other stem cells as well.

  15. Dopamine Regulates Mobilization of Mesenchymal Stem Cells during Wound Angiogenesis

    PubMed Central

    Shome, Saurav; Dasgupta, Partha Sarathi; Basu, Sujit

    2012-01-01

    Angiogenesis is an important step in the complex biological and molecular events leading to successful healing of dermal wounds. Among the different cellular effectors of wound angiogenesis, the role of mesenchymal stem cells (MSCs) is of current interest due to their transdifferentiation and proangiogenic potentials. Skin is richly innervated by sympathetic nerves which secrete dopamine (DA) and we have recently shown that concentration of DA present in synaptic cleft can significantly inhibit wound tissue neovascularization. As recent reports indicate that MSCs by mobilizing into wound bed play an important role in promoting wound angiogenesis, we therefore investigated the effect of DA on the migration of MSCs in wound tissues. DA acted through its D2 receptors present in the MSCs to inhibit their mobilization to the wound beds by suppressing Akt phosphorylation and actin polymerization. In contrast, this inhibitory effect of DA was reversed after treatment with specific DA D2 receptor antagonist. Increased mobilization of MSCs was demonstrated in the wound site following blockade of DA D2 receptor mediated actions, and this in turn was associated with significantly more angiogenesis in wound tissues. This study is of translational value and indicates use of DA D2 receptor antagonists to stimulate mobilization of these stem cells for faster regeneration of damaged tissues. PMID:22355389

  16. Epigenetic regulation of planarian stem cells by the SET1/MLL family of histone methyltransferases.

    PubMed

    Hubert, Amy; Henderson, Jordana M; Ross, Kelly G; Cowles, Martis W; Torres, Jessica; Zayas, Ricardo M

    2013-01-01

    Chromatin regulation is a fundamental mechanism underlying stem cell pluripotency, differentiation, and the establishment of cell type-specific gene expression profiles. To examine the role of chromatin regulation in stem cells in vivo, we study regeneration in the freshwater planarian Schmidtea mediterranea. These animals possess a high concentration of pluripotent stem cells, which are capable of restoring any damaged or lost tissues after injury or amputation. Here, we identify the S. mediterranea homologs of the SET1/MLL family of histone methyltransferases and COMPASS and COMPASS-like complex proteins and investigate their role in stem cell function during regeneration. We identified six S. mediterranea homologs of the SET1/MLL family (set1, mll1/2, trr-1, trr-2, mll5-1 and mll5-2), characterized their patterns of expression in the animal, and examined their function by RNAi. All members of this family are expressed in the stem cell population and differentiated tissues. We show that set1, mll1/2, trr-1, and mll5-2 are required for regeneration and that set1, trr-1 and mll5-2 play roles in the regulation of mitosis. Most notably, knockdown of the planarian set1 homolog leads to stem cell depletion. A subset of planarian homologs of COMPASS and COMPASS-like complex proteins are also expressed in stem cells and implicated in regeneration, but the knockdown phenotypes suggest that some complex members also function in other aspects of planarian biology. This work characterizes the function of the SET1/MLL family in the context of planarian regeneration and provides insight into the role of these enzymes in adult stem cell regulation in vivo.

  17. Epigenetic regulation of planarian stem cells by the SET1/MLL family of histone methyltransferases

    PubMed Central

    Hubert, Amy; Henderson, Jordana M.; Ross, Kelly G.; Cowles, Martis W.; Torres, Jessica; Zayas, Ricardo M.

    2013-01-01

    Chromatin regulation is a fundamental mechanism underlying stem cell pluripotency, differentiation, and the establishment of cell type-specific gene expression profiles. To examine the role of chromatin regulation in stem cells in vivo, we study regeneration in the freshwater planarian Schmidtea mediterranea. These animals possess a high concentration of pluripotent stem cells, which are capable of restoring any damaged or lost tissues after injury or amputation. Here, we identify the S. mediterranea homologs of the SET1/MLL family of histone methyltransferases and COMPASS and COMPASS-like complex proteins and investigate their role in stem cell function during regeneration. We identified six S. mediterranea homologs of the SET1/MLL family (set1, mll1/2, trr-1, trr-2, mll5–1 and mll5–2), characterized their patterns of expression in the animal, and examined their function by RNAi. All members of this family are expressed in the stem cell population and differentiated tissues. We show that set1, mll1/2, trr-1, and mll5–2 are required for regeneration and that set1, trr-1 and mll5–2 play roles in the regulation of mitosis. Most notably, knockdown of the planarian set1 homolog leads to stem cell depletion. A subset of planarian homologs of COMPASS and COMPASS-like complex proteins are also expressed in stem cells and implicated in regeneration, but the knockdown phenotypes suggest that some complex members also function in other aspects of planarian biology. This work characterizes the function of the SET1/MLL family in the context of planarian regeneration and provides insight into the role of these enzymes in adult stem cell regulation in vivo. PMID:23235145

  18. Concise Review: Plasma and Nuclear Membranes Convey Mechanical Information to Regulate Mesenchymal Stem Cell Lineage.

    PubMed

    Uzer, Gunes; Fuchs, Robyn K; Rubin, Janet; Thompson, William R

    2016-06-01

    Numerous factors including chemical, hormonal, spatial, and physical cues determine stem cell fate. While the regulation of stem cell differentiation by soluble factors is well-characterized, the role of mechanical force in the determination of lineage fate is just beginning to be understood. Investigation of the role of force on cell function has largely focused on "outside-in" signaling, initiated at the plasma membrane. When interfaced with the extracellular matrix, the cell uses integral membrane proteins, such as those found in focal adhesion complexes to translate force into biochemical signals. Akin to these outside-in connections, the internal cytoskeleton is physically linked to the nucleus, via proteins that span the nuclear membrane. Although structurally and biochemically distinct, these two forms of mechanical coupling influence stem cell lineage fate and, when disrupted, often lead to disease. Here we provide an overview of how mechanical coupling occurs at the plasma and nuclear membranes. We also discuss the role of force on stem cell differentiation, with focus on the biochemical signals generated at the cell membrane and the nucleus, and how those signals influence various diseases. While the interaction of stem cells with their physical environment and how they respond to force is complex, an understanding of the mechanical regulation of these cells is critical in the design of novel therapeutics to combat diseases associated with aging, cancer, and osteoporosis. Stem Cells 2016;34:1455-1463. © 2016 AlphaMed Press.

  19. Development of Stepwise Osteogenesis-mimicking Matrices for the Regulation of Mesenchymal Stem Cell Functions*

    PubMed Central

    Hoshiba, Takashi; Kawazoe, Naoki; Tateishi, Tetsuya; Chen, Guoping

    2009-01-01

    An extracellular microenvironment, including an extracellular matrix (ECM), is an important factor in regulating stem cell differentiation. During tissue development, the ECM is dynamically remodeled to regulate stem cell functions. Here, we developed matrices mimicking ECM remodeling during the osteogenesis of mesenchymal stem cells (MSCs). The matrices were prepared from cultured MSCs controlled at different stages of osteogenesis and referred to as “stepwise osteogenesis-mimicking matrices.” The matrices supported the adhesion and proliferation of MSCs and showed different effects on the osteogenesis of MSCs. On the matrices mimicking the early stage of osteogenesis (early stage matrices), the osteogenesis occurred more rapidly than did that on the matrices mimicking undifferentiated stem cells (stem cell matrices) and the late stage of osteogenesis (late stage matrices). RUNX2 was similarly expressed when MSCs were cultured on both the early stage and late stage matrices but decreased on the stem cell matrices. PPARG expression in the MSCs cultured on the late stage matrices was higher than for those cultured on the stem cell and early stage matrices. This increase of PPARG expression was caused by the suppression of the amount of β-catenin and downstream signal transduction. These results demonstrate that the osteogenesis-mimicking matrices had different effects on the osteogenesis of MSCs, and the early stage matrices provided a favorable microenvironment for the osteogenesis. PMID:19762920

  20. Microfluidic perfusion for regulating diffusible signaling in stem cells.

    PubMed

    Blagovic, Katarina; Kim, Lily Y; Voldman, Joel

    2011-01-01

    Autocrine & paracrine signaling are widespread both in vivo and in vitro, and are particularly important in embryonic stem cell (ESC) pluripotency and lineage commitment. Although autocrine signaling via fibroblast growth factor-4 (FGF4) is known to be required in mouse ESC (mESC) neuroectodermal specification, the question of whether FGF4 autocrine signaling is sufficient, or whether other soluble ligands are also involved in fate specification, is unknown. The spatially confined and closed-loop nature of diffusible signaling makes its experimental control challenging; current experimental approaches typically require prior knowledge of the factor/receptor in order to modulate the loop. A new approach explored in this work is to leverage transport phenomena at cellular resolution to downregulate overall diffusible signaling through the physical removal of cell-secreted ligands. We develop a multiplex microfluidic platform to continuously remove cell-secreted (autocrine\\paracrine) factors to downregulate diffusible signaling. By comparing cell growth and differentiation in side-by-side chambers with or without added cell-secreted factors, we isolate the effects of diffusible signaling from artifacts such as shear, nutrient depletion, and microsystem effects, and find that cell-secreted growth factor(s) are required during neuroectodermal specification. Then we induce FGF4 signaling in minimal chemically defined medium (N2B27) and inhibit FGF signaling in fully supplemented differentiation medium with cell-secreted factors to determine that the non-FGF cell-secreted factors are required to promote growth of differentiating mESCs. Our results demonstrate for the first time that flow can downregulate autocrine\\paracrine signaling and examine sufficiency of extracellular factors. We show that autocrine\\paracrine signaling drives neuroectodermal commitment of mESCs through both FGF4-dependent and -independent pathways. Overall, by uncovering autocrine

  1. The effect of stem cell proliferation regulators demonstrated with an in vitro assay.

    PubMed

    Pragnell, I B; Wright, E G; Lorimore, S A; Adam, J; Rosendaal, M; DeLamarter, J F; Freshney, M; Eckmann, L; Sproul, A; Wilkie, N

    1988-07-01

    Spleen colony formation after transplantation of bone marrow cells into irradiated mice has been used as an assay for hematopoietic stem cells (CFU-S), but has serious limitations intrinsic to an in vivo assay. In this report we describe experiments using an in vitro clonogenic assay that is especially suitable for studies of stem cell regulation as defined growth factors and normal untreated bone marrow can be used. We have demonstrated that the colony-forming cells have proliferative properties in common with CFU-S and respond to specific proliferation regulators previously detected using the spleen colony assay.

  2. An RNAi screen reveals intestinal regulators of branching morphogenesis, differentiation, and stem cell proliferation in planarians.

    PubMed

    Forsthoefel, David J; James, Noëlle P; Escobar, David J; Stary, Joel M; Vieira, Ana P; Waters, Forrest A; Newmark, Phillip A

    2012-10-16

    Planarians grow and regenerate organs by coordinating proliferation and differentiation of pluripotent stem cells with remodeling of postmitotic tissues. Understanding how these processes are orchestrated requires characterizing cell-type-specific gene expression programs and their regulation during regeneration and homeostasis. To this end, we analyzed the expression profile of planarian intestinal phagocytes, cells responsible for digestion and nutrient storage/distribution. Utilizing RNA interference, we identified cytoskeletal regulators required for intestinal branching morphogenesis and a modulator of bioactive sphingolipid metabolism, ceramide synthase, required for the production of functional phagocytes. Additionally, we found that a gut-enriched homeobox transcription factor, nkx-2.2, is required for somatic stem cell proliferation, suggesting a niche-like role for phagocytes. Identification of evolutionarily conserved regulators of intestinal branching, differentiation, and stem cell dynamics demonstrates the utility of the planarian digestive system as a model for elucidating the mechanisms controlling postembryonic organogenesis.

  3. An RNAi screen reveals intestinal regulators of branching morphogenesis, differentiation, and stem cell proliferation in planarians

    PubMed Central

    Forsthoefel, David J.; James, Noelle P.; Escobar, David J.; Stary, Joel M.; Vieira, Ana P.; Waters, Forrest A.; Newmark, Phillip A.

    2012-01-01

    SUMMARY Planarians grow and regenerate organs by coordinating proliferation and differentiation of pluripotent stem cells with remodeling of post-mitotic tissues. Understanding how these processes are orchestrated requires characterizing cell type-specific gene expression programs and their regulation during regeneration and homeostasis. To this end, we analyzed the expression profile of planarian intestinal phagocytes, cells responsible for digestion and nutrient storage/distribution. Utilizing RNA interference, we identified cytoskeletal regulators required for intestinal branching morphogenesis, and a modulator of bioactive sphingolipid metabolism, ceramide synthase, required for the production of functional phagocytes. Additionally, we found that a gut-enriched homeobox transcription factor, nkx-2.2, is required for somatic stem cell proliferation, suggesting a niche-like role for phagocytes. Identification of evolutionarily conserved regulators of intestinal branching, differentiation, and stem cell dynamics demonstrates the utility of the planarian digestive system as a model for elucidating the mechanisms controlling post-embryonic organogenesis. PMID:23079596

  4. Foxp1 maintains hair follicle stem cell quiescence through regulation of Fgf18

    PubMed Central

    Leishman, Erin; Howard, Jeffrey M.; Garcia, Gloria E.; Miao, Qi; Ku, Amy T.; Dekker, Joseph D.; Tucker, Haley; Nguyen, Hoang

    2013-01-01

    Hair follicles cyclically degenerate and regenerate throughout adult life and require regular stem cell activation to drive the cycle. In the resting phase of the hair cycle, hair follicle stem cells are maintained in a quiescent state until they receive signals to proliferate. We found that the forkhead transcription factor Foxp1 is crucial for maintaining the quiescence of hair follicle stem cells. Loss of Foxp1 in skin epithelial cells leads to precocious stem cell activation, resulting in drastic shortening of the quiescent phase of the hair cycle. Conversely, overexpression of Foxp1 in keratinocytes prevents cell proliferation by promoting cell cycle arrest. Finally, through both gain- and loss-of-function studies, we identify fibroblast growth factor 18 (Fgf18) as the key downstream target of Foxp1. We show that exogenously supplied FGF18 can prevent the hair follicle stem cells of Foxp1 null mice from being prematurely activated. As Fgf18 controls the length of the quiescent phase and is a key downstream target of Foxp1, our data strongly suggest that Foxp1 regulates the quiescent stem cell state in the hair follicle stem cell niche by controlling Fgf18 expression. PMID:23946441

  5. Lysine-specific demethylase 1 regulates differentiation onset and migration of trophoblast stem cells

    NASA Astrophysics Data System (ADS)

    Zhu, Dongmei; Hölz, Stefanie; Metzger, Eric; Pavlovic, Mihael; Jandausch, Anett; Jilg, Cordula; Galgoczy, Petra; Herz, Corinna; Moser, Markus; Metzger, Daniel; Günther, Thomas; Arnold, Sebastian J.; Schüle, Roland

    2014-01-01

    Propagation and differentiation of stem cell populations are tightly regulated to provide sufficient cell numbers for tissue formation while maintaining the stem cell pool. Embryonic parts of the mammalian placenta are generated from differentiating trophoblast stem cells (TSCs) invading the maternal decidua. Here we demonstrate that lysine-specific demethylase 1 (Lsd1) regulates differentiation onset of TSCs. Deletion of Lsd1 in mice results in the reduction of TSC number, diminished formation of trophectoderm tissues and early embryonic lethality. Lsd1-deficient TSCs display features of differentiation initiation, including alterations of cell morphology, and increased migration and invasion. We show that increased TSC motility is mediated by the premature expression of the transcription factor Ovol2 that is directly repressed by Lsd1 in undifferentiated cells. In summary, our data demonstrate that the epigenetic modifier Lsd1 functions as a gatekeeper for the differentiation onset of TSCs, whereby differentiation-associated cell migration is controlled by the transcription factor Ovol2.

  6. The roles and regulation of Sertoli cells in fate determinations of spermatogonial stem cells and spermatogenesis.

    PubMed

    Hai, Yanan; Hou, Jingmei; Liu, Yun; Liu, Yang; Yang, Hao; Li, Zheng; He, Zuping

    2014-05-01

    Spermatogenesis is a complex process by which spermatogonial stem cells (SSCs) self-renew and differentiate into spermatozoa under the elaborate coordination of testicular microenvironment, namely, niche. Sertoli cells, which locate around male germ cells, are the most critical component of the niche. Significant progress has recently been made by peers and us on uncovering the effects of Sertoli cells on regulating fate determinations of SSCs. Here we addressed the roles and regulation of Sertoli cells in normal and abnormal spermatogenesis. Specifically, we summarized the biological characteristics of Sertoli cells, and we emphasized the roles of Sertoli cells in mediating the self-renewal, differentiation, apoptosis, de-differentiation, and trans-differentiation of SSCs. The association between abnormal function of Sertoli cells and impaired spermatogenesis was discussed. Finally, we highlighted several issues to be addressed for further investigation on the effects and mechanisms of Sertoli cells in spermatogenesis. Since Sertoli cells are the key supportive cells for SSCs and they are very receptive to modification, a better understanding of the roles and regulation of Sertoli cells in SSC biology and spermatogenesis would make it feasible to identify novel targets for gene therapy of male infertility as well as seek more efficient and safer strategies for male contraception.

  7. Hematopoietic Stem Cell Differentiation Regulated by a Single Ubiquitin Ligase: Substrate Complex

    PubMed Central

    Reavie, Linsey; Gatta, Giusy Della; Crusio, Kelly; Aranda-Orgilles, Beatriz; Buckley, Shannon M.; Thompson, Benjamin; Lee, Eugine; Gao, Jie; Bredemeyer, Andrea L.; Helmink, Beth A.; Zavadil, Jiri; Sleckman, Barry P.; Palomero, Teresa; Ferrando, Adolfo; Aifantis, Iannis

    2009-01-01

    Hematopoietic stem cell (HSC) differentiation is regulated by cell-intrinsic and extrinsic cues. In addition to transcriptional regulation, post-translational regulation may also control HSC differentiation. To test this hypothesis, we visualized ubiquitin-regulated protein stability of a single transcription factor, c-Myc. The stability of c-Myc protein was instructive of HSC quiescence and c-Myc protein abundance was controlled by the ubiquitin ligase Fbw7. Fine changes in stability of c-Myc protein regulated the HSC “gene expression signature”. Using whole genome genomic approaches, we identified specific regulators of HSC function that are directly controlled by c-Myc binding, however adult HSCs and embryonic stem cells sense and interpret distinctly c-Myc regulated gene expression. These studies show a ubiquitin ligase substrate pair can orchestrate the molecular program of HSC differentiation. PMID:20081848

  8. Regulation of haematopoietic stem cell proliferation by stimulatory factors produced by murine fetal and adult liver.

    PubMed Central

    Dawood, K A; Briscoe, C V; Thomas, D B; Riches, A C

    1990-01-01

    Haematopoietic stem cells in murine fetal liver are in a proliferative state unlike those in normal bone marrow which are quiescent. A regulatory activity is produced by cells in the fetal liver which will switch quiescent normal bone marrow haematopoietic stem cells into cell cycle in vitro. This regulator from Day 15 fetal liver cells is produced by adherent cells and by cells fractionated on a Percoll gradient in the 1.064 and 1.076 g per cm3 density bands but not in the 1.123 g per cm3 band. Colony-stimulating factor cannot be detected in the supernatants containing the stem cell regulatory activity. The stimulator can be detected in supernatants produced from cell suspensions of liver cells at Day 15 and Day 17 of gestation and 24 hours and 72 hours after birth. However by 1 week after birth the production of the stimulator decreases and is undetectable 3 and 10 weeks after birth. The total numbers of haematopoietic stem cells (CFU-S) in fetal liver decrease from Day 15 of gestation and only small numbers are present 1 week after birth. Thus the decline in the production of haematopoietic stem cell proliferation stimulator correlates with the decrease in haematopoietic stem cell numbers in the liver through gestation and after birth. PMID:2323992

  9. Revealed: The spy who regulates neuroblastoma stem cells.

    PubMed

    Vora, Parvez; Venugopal, Chitra; Singh, Sheila K

    2014-11-30

    Neuroblastoma (NB), an embryonal tumour of the sympathetic nervous system, is thought to originate from undifferentiated neural crest cells and is known to exhibit extremely heterogeneous biological and clinical behaviors. Occurring in very young children, the median age at diagnosis is 17 months and it accounts for 10% of all pediatric cancer mortalities. The standard treatment regimen for patients with high-risk NB includes induction and surgery followed by isotretinoin or Accutane (13-cis retinoic acid) treatment, which is shown to induce terminal differentiation of NB cells. However, molecular regulators that maintain an undifferentiated phenotype in NB cells are still poorly understood.

  10. Stem cells are differentially regulated during development, regeneration and homeostasis in flatworms.

    PubMed

    De Mulder, Katrien; Pfister, Daniela; Kuales, Georg; Egger, Bernhard; Salvenmoser, Willi; Willems, Maxime; Steger, Jessica; Fauster, Katja; Micura, Ronald; Borgonie, Gaetan; Ladurner, Peter

    2009-10-01

    The flatworm stem cell system is exceptional within the animal kingdom, as totipotent stem cells (neoblasts) are the only dividing cells within the organism. In contrast to most organisms, piwi-like gene expression in flatworms is extended from germ cells to somatic stem cells. We describe the isolation and characterization of the piwi homologue macpiwi in the flatworm Macrostomum lignano. We use in situ hybridization, antibody staining and RNA interference to study macpiwi expression and function in adults, during postembryonic development, regeneration and upon starvation. We found novelties regarding piwi function and observed differences to current piwi functions in flatworms. First, macpiwi was essential for the maintenance of somatic stem cells in adult animals. A knock-down of macpiwi led to a complete elimination of stem cells and death of the animals. Second, the regulation of stem cells was different in adults and regenerates compared to postembryonic development. Third, sexual reproduction of M. lignano allowed to follow germline formation during postembryonic development, regeneration, and starvation. Fourth, piwi expression in hatchlings further supports an embryonic formation of the germline in M. lignano. Our findings address new questions in flatworm stem cell research and provide a basis for comparison with higher organisms.

  11. Phytoestrogens regulate the proliferation and expression of stem cell factors in cell lines of malignant testicular germ cell tumors

    PubMed Central

    HASIBEDER, ASTRID; VENKATARAMANI, VIVEK; THELEN, PAUL; RADZUN, HEINZ-JOACHIM; SCHWEYER, STEFAN

    2013-01-01

    Phytoestrogens have been shown to exert anti-proliferative effects on different cancer cells. In addition it could be demonstrated that inhibition of proliferation is associated with downregulation of the known stem cell factors NANOG, POU5F1 and SOX2 in tumor cells. We demonstrate the potential of Belamcanda chinensis extract (BCE) and tectorigenin as anticancer drugs in cell lines of malignant testicular germ cell tumor cells (TGCT) by inhibition of proliferation and regulating the expression of stem cell factors. The TGCT cell lines TCam-2 and NTera-2 were treated with BCE or tectorigenin and MTT assay was used to measure the proliferation of tumor cells. In addition, the expression of stem cell factors was analyzed by quantitative PCR and western blot analysis. Furthermore, global expression analysis was performed by microarray technique. BCE and tectorigenin inhibited proliferation and downregulated the stem cell factors NANOG and POU5F1 in TGCT cells. In addition, gene expression profiling revealed induction of genes important for the differentiation and inhibition of oncogenes. Utilizing connectivity map in an attempt to elucidate mechanism underlying BCE treatments we found highly positive association to histone deacetylase inhibitors (HDACi) amongst others. Causing no histone deacetylase inhibition, the effects of BCE on proliferation and stem cell factors may be based on histone-independent mechanisms such as direct hyperacetylation of transcription factors. Based on these findings, phytoestrogens may be useful as new agents in the treatment of TGCT. PMID:23969837

  12. Germline self-renewal requires cyst stem cells and stat regulates niche adhesion in Drosophila testes.

    PubMed

    Leatherman, Judith L; Dinardo, Stephen

    2010-08-01

    Adults maintain tissue-specific stem cells through niche signals. A model for niche function is the Drosophila melanogaster testis, where a small cluster of cells called the hub produce locally available signals that allow only adjacent cells to self-renew. We show here that the principal signalling pathway implicated in this niche, chemokine activation of STAT, does not primarily regulate self-renewal of germline stem cells (GSCs), but rather governs GSC adhesion to hub cells. In fact, GSC renewal does not require hub cell contact, as GSCs can be renewed solely by contact with the second resident stem cell population, somatic cyst stem cells (CySCs), and this involves BMP signalling. These data suggest a modified paradigm whereby the hub cells function as architects of the stem cell environment, drawing into proximity cellular components necessary for niche function. Self-renewal functions are shared by the hub cells and the CySCs. This work also reconciles key differences in GSC renewal between Drosophila testis and ovary niches, and highlights how a niche can coordinate the production of distinct lineages by having one stem cell type rely on a second.

  13. ETV5 regulates sertoli cell chemokines involved in mouse stem/progenitor spermatogonia maintenance.

    PubMed

    Simon, Liz; Ekman, Gail C; Garcia, Thomas; Carnes, Kay; Zhang, Zhen; Murphy, Theresa; Murphy, Kenneth M; Hess, Rex A; Cooke, Paul S; Hofmann, Marie-Claude

    2010-10-01

    Spermatogonial stem cells are the only stem cells in the body that transmit genetic information to offspring. Although growth factors responsible for self-renewal of these cells are known, the factors and mechanisms that attract and physically maintain these cells within their microenvironment are poorly understood. Mice with targeted disruption of Ets variant gene 5 (Etv5) show total loss of stem/progenitor spermatogonia following the first wave of spermatogenesis, resulting in a Sertoli cell-only phenotype and aspermia. Microarray analysis of primary Sertoli cells from Etv5 knockout (Etv5(-/-)) versus wild-type (WT) mice revealed significant decreases in expression of several chemokines. Chemotaxis assays demonstrated that migration of stem/progenitor spermatogonia toward Etv5(-/-) Sertoli cells was significantly decreased compared to migration toward WT Sertoli cells. Interestingly, differentiating spermatogonia, spermatocytes, and round spermatids were not chemoattracted by WT Sertoli cells, whereas stem/progenitor spermatogonia showed a high and significant chemotactic index. Rescue assays using recombinant chemokines indicated that C-C-motif ligand 9 (CCL9) facilitates Sertoli cell chemoattraction of stem/progenitor spermatogonia, which express C-C-receptor type 1 (CCR1). In addition, there is protein-DNA interaction between ETV5 and Ccl9, suggesting that ETV5 might be a direct regulator of Ccl9 expression. Taken together, our data show for the first time that Sertoli cells are chemoattractive for stem/progenitor spermatogonia, and that production of specific chemokines is regulated by ETV5. Therefore, changes in chemokine production and consequent decreases in chemoattraction by Etv5(-/-) Sertoli cells helps to explain stem/progenitor spermatogonia loss in Etv5(-/-) mice.

  14. MicroRNA regulation of cancer stem cells and therapeutic implications.

    PubMed

    DeSano, Jeffrey T; Xu, Liang

    2009-12-01

    MicroRNAs (miRNAs) are a class of endogenous non-protein-coding RNAs that function as important regulatory molecules by negatively regulating gene and protein expression via the RNA interference (RNAi) machinery. MiRNAs have been implicated to control a variety of cellular, physiological, and developmental processes. Aberrant expressions of miRNAs are connected to human diseases such as cancer. Cancer stem cells are a small subpopulation of cells identified in a variety of tumors that are capable of self-renewal and differentiation. Dysregulation of stem cell self-renewal is a likely requirement for the initiation and formation of cancer. Furthermore, cancer stem cells are a very likely cause of resistance to current cancer treatments, as well as relapse in cancer patients. Understanding the biology and pathways involved with cancer stem cells offers great promise for developing better cancer therapies, and might one day even provide a cure for cancer. Emerging evidence demonstrates that miRNAs are involved in cancer stem cell dysregulation. Recent studies also suggest that miRNAs play a critical role in carcinogenesis and oncogenesis by regulating cell proliferation and apoptosis as oncogenes or tumor suppressors, respectively. Therefore, molecularly targeted miRNA therapy could be a powerful tool to correct the cancer stem cell dysregulation.

  15. aPKCλ controls epidermal homeostasis and stem cell fate through regulation of division orientation

    PubMed Central

    Niessen, Michaela T.; Scott, Jeanie; Zielinski, Julia G.; Vorhagen, Susanne; Sotiropoulou, Panagiota A.; Blanpain, Cédric

    2013-01-01

    The atypical protein kinase C (aPKC) is a key regulator of polarity and cell fate in lower organisms. However, whether mammalian aPKCs control stem cells and fate in vivo is not known. Here we show that loss of aPKCλ in a self-renewing epithelium, the epidermis, disturbed tissue homeostasis, differentiation, and stem cell dynamics, causing progressive changes in this tissue. This was accompanied by a gradual loss of quiescent hair follicle bulge stem cells and a temporary increase in proliferating progenitors. Lineage tracing analysis showed that loss of aPKCλ altered the fate of lower bulge/hair germ stem cells. This ultimately led to loss of proliferative potential, stem cell exhaustion, alopecia, and premature aging. Inactivation of aPKCλ produced more asymmetric divisions in different compartments, including the bulge. Thus, aPKCλ is crucial for homeostasis of self-renewing stratifying epithelia, and for the regulation of cell fate, differentiation, and maintenance of epidermal bulge stem cells likely through its role in balancing symmetric and asymmetric division. PMID:24019538

  16. Lis1 regulates asymmetric division in hematopoietic stem cells and in leukemia

    PubMed Central

    Zimdahl, Bryan; Ito, Takahiro; Blevins, Allen; Bajaj, Jeevisha; Konuma, Takaaki; Weeks, Joi; Koechlein, Claire S.; Kwon, Hyog Young; Arami, Omead; Rizzieri, David; Broome, H. Elizabeth; Chuah, Charles; Oehler, Vivian G.; Sasik, Roman; Hardiman, Gary; Reya, Tannishtha

    2014-01-01

    Cell fate can be controlled through asymmetric division and segregation of protein determinants. But the regulation of this process in the hematopoietic system is poorly understood. Here we show that the dynein binding protein Lis1 (Pafah1b1) is critically required for blood formation and hematopoietic stem cell function. Conditional deletion of Lis1 in the hematopoietic system led to a severe bloodless phenotype, depletion of the stem cell pool and embryonic lethality. Further, the loss of Lis1 accelerated cell differentiation, in part through defects in spindle positioning and inheritance of cell fate determinants. Finally, deletion of Lis1 blocked propagation of myeloid leukemia and led to a marked improvement in animal survival, suggesting that Lis1 is also required for oncogenic growth. These data identify a key role for Lis1 in hematopoietic stem cells, and mark the directed control of asymmetric division as a critical regulator of normal and malignant hematopoietic development. PMID:24487275

  17. Dipeptide species regulate p38MAPK-Smad3 signalling to maintain chronic myelogenous leukaemia stem cells.

    PubMed

    Naka, Kazuhito; Jomen, Yoshie; Ishihara, Kaori; Kim, Junil; Ishimoto, Takahiro; Bae, Eun-Jin; Mohney, Robert P; Stirdivant, Steven M; Oshima, Hiroko; Oshima, Masanobu; Kim, Dong-Wook; Nakauchi, Hiromitsu; Takihara, Yoshihiro; Kato, Yukio; Ooshima, Akira; Kim, Seong-Jin

    2015-08-20

    Understanding the specific survival of the rare chronic myelogenous leukaemia (CML) stem cell population could provide a target for therapeutics aimed at eradicating these cells. However, little is known about how survival signalling is regulated in CML stem cells. In this study, we survey global metabolic differences between murine normal haematopoietic stem cells (HSCs) and CML stem cells using metabolomics techniques. Strikingly, we show that CML stem cells accumulate significantly higher levels of certain dipeptide species than normal HSCs. Once internalized, these dipeptide species activate amino-acid signalling via a pathway involving p38MAPK and the stemness transcription factor Smad3, which promotes CML stem cell maintenance. Importantly, pharmacological inhibition of dipeptide uptake inhibits CML stem cell activity in vivo. Our results demonstrate that dipeptide species support CML stem cell maintenance by activating p38MAPK-Smad3 signalling in vivo, and thus point towards a potential therapeutic target for CML treatment.

  18. Dipeptide species regulate p38MAPK–Smad3 signalling to maintain chronic myelogenous leukaemia stem cells

    PubMed Central

    Naka, Kazuhito; Jomen, Yoshie; Ishihara, Kaori; Kim, Junil; Ishimoto, Takahiro; Bae, Eun-Jin; Mohney, Robert P.; Stirdivant, Steven M.; Oshima, Hiroko; Oshima, Masanobu; Kim, Dong-Wook; Nakauchi, Hiromitsu; Takihara, Yoshihiro; Kato, Yukio; Ooshima, Akira; Kim, Seong-Jin

    2015-01-01

    Understanding the specific survival of the rare chronic myelogenous leukaemia (CML) stem cell population could provide a target for therapeutics aimed at eradicating these cells. However, little is known about how survival signalling is regulated in CML stem cells. In this study, we survey global metabolic differences between murine normal haematopoietic stem cells (HSCs) and CML stem cells using metabolomics techniques. Strikingly, we show that CML stem cells accumulate significantly higher levels of certain dipeptide species than normal HSCs. Once internalized, these dipeptide species activate amino-acid signalling via a pathway involving p38MAPK and the stemness transcription factor Smad3, which promotes CML stem cell maintenance. Importantly, pharmacological inhibition of dipeptide uptake inhibits CML stem cell activity in vivo. Our results demonstrate that dipeptide species support CML stem cell maintenance by activating p38MAPK–Smad3 signalling in vivo, and thus point towards a potential therapeutic target for CML treatment. PMID:26289811

  19. Solid Lipid Nanoparticles Regulate Functional Assortment of Mouse Mesenchymal Stem Cells

    PubMed Central

    Chabra, S; Ranjan, M; Bhandari, R; Kaur, T; Aggrawal, M; Puri, V; Mahajan, N; Kaur, IP; Puri, S; Sobti, RC

    2011-01-01

    A rapid decline in self-renewability, viability and function, of isolated stem cells are major hurdles in developing cell based therapies. There has been an increasing interest towards identifying a support material for maintaining stem cell features of the isolated cells. Pioneering observations of the present paper, demonstrate functionally diverse potential of Solid Lipid Nanoparticles (SLNs) in deciding the fate & behavior of mouse mesenchymal stem cell. The evidences are provided to show the dual nature of the SLNs for being a scaffold for the stem cell attachment, to retain stemness, and as reagent for inducing stem cell differentiation. Scanning electron microscopic examinations together with expression analysis were used to conform to such observations. Results of the study thus suggest that Solid lipid nanoparticles can be used as a good support material when functionalized to achieve adhesive properties and as a molecular paradigm for studying the adipocytic differentiation. We envisage a new role of SLNs towards regulating stem cell character by orchestrating the structural alignment during preparation of Solid lipid nanoparticles PMID:24693174

  20. ETV5 Regulates Sertoli Cell Chemokines Involved in Mouse Stem/Progenitor Spermatogonia Maintenance

    PubMed Central

    Simon, Liz; Ekman, Gail C; Garcia, Thomas; Carnes, Kay; Zhang, Zhen; Murphy, Theresa; Murphy, Kenneth M; Hess, Rex A; Cooke, Paul S; Hofmann, Marie–Claude

    2010-01-01

    Spermatogonial stem cells are the only stem cells in the body that transmit genetic information to offspring. Although growth factors responsible for self–renewal of these cells are known, the factors and mechanisms that attract and physically maintain these cells within their microenvironment are poorly understood. Mice with targeted disruption of Ets variant gene 5 (Etv5) show total loss of stem/progenitor spermatogonia following the first wave of spermatogenesis, resulting in a Sertoli cell–only phenotype and aspermia. Microarray analysis of primary Sertoli cells from Etv5 knockout (Etv5−/−) versus wild–type (WT) mice revealed significant decreases in expression of several chemokines. Chemotaxis assays demonstrated that migration of stem/progenitor spermatogonia toward Etv5−/− Sertoli cells was significantly decreased compared to migration toward WT Sertoli cells. Interestingly, differentiating spermatogonia, spermatocytes, and round spermatids were not chemoattracted by WT Sertoli cells, whereas stem/progenitor spermatogonia showed a high and significant chemotactic index. Rescue assays using recombinant chemokines indicated that C-C-motif ligand 9 (CCL9) facilitates Sertoli cell chemoattraction of stem/progenitor spermatogonia, which express C-C-receptor type 1 (CCR1). In addition, there is protein–DNA interaction between ETV5 and Ccl9, suggesting that ETV5 might be a direct regulator of Ccl9 expression. Taken together, our data show for the first time that Sertoli cells are chemoattractive for stem/progenitor spermatogonia, and that production of specific chemokines is regulated by ETV5. Therefore, changes in chemokine production and consequent decreases in chemoattraction by Etv5−/− Sertoli cells helps to explain stem/progenitor spermatogonia loss in Etv5−/− mice. PMID:20799334

  1. MicroRNA93 Regulates Proliferation and Differentiation of Normal and Malignant Breast Stem Cells

    PubMed Central

    Liu, Suling; Patel, Shivani H.; Ginestier, Christophe; Ibarra, Ingrid; Martin-Trevino, Rachel; Bai, Shoumin; McDermott, Sean P.; Shang, Li; Ke, Jia; Ou, Sing J.; Heath, Amber; Zhang, Kevin J.; Korkaya, Hasan; Clouthier, Shawn G.; Charafe-Jauffret, Emmanuelle; Birnbaum, Daniel; Hannon, Gregory J.; Wicha, Max S.

    2012-01-01

    MicroRNAs (miRNAs) play important roles in normal cellular differentiation and oncogenesis. microRNA93 (mir-93), a member of the mir106b-25 cluster, located in intron 13 of the MCM7 gene, although frequently overexpressed in human malignancies may also function as a tumor suppressor gene. Using a series of breast cancer cell lines representing different stages of differentiation and mouse xenograft models, we demonstrate that mir-93 modulates the fate of breast cancer stem cells (BCSCs) by regulating their proliferation and differentiation states. In “claudinlow” SUM159 cells, expression of mir-93 induces Mesenchymal-Epithelial Transition (MET) associated with downregulation of TGFβ signaling and downregulates multiple stem cell regulatory genes, including JAK1, STAT3, AKT3, SOX4, EZH1, and HMGA2, resulting in cancer stem cell (CSC) depletion. Enforced expression of mir-93 completely blocks tumor development in mammary fat pads and development of metastases following intracardiac injection in mouse xenografts. The effect of mir-93 on the CSC population is dependent on the cellular differentiation state, with mir-93 expression increasing the CSC population in MCF7 cells that display a more differentiated “luminal” phenotype. mir-93 also regulates the proliferation and differentiation of normal breast stem cells isolated from reduction mammoplasties. These studies demonstrate that miRNAs can regulate the states and fates of normal and malignant mammary stem cells, findings which have important biological and clinical implications. PMID:22685420

  2. Microfluidic Perfusion for Regulating Diffusible Signaling in Stem Cells

    PubMed Central

    Blagovic, Katarina; Kim, Lily Y.; Voldman, Joel

    2011-01-01

    Background Autocrine & paracrine signaling are widespread both in vivo and in vitro, and are particularly important in embryonic stem cell (ESC) pluripotency and lineage commitment. Although autocrine signaling via fibroblast growth factor-4 (FGF4) is known to be required in mouse ESC (mESC) neuroectodermal specification, the question of whether FGF4 autocrine signaling is sufficient, or whether other soluble ligands are also involved in fate specification, is unknown. The spatially confined and closed-loop nature of diffusible signaling makes its experimental control challenging; current experimental approaches typically require prior knowledge of the factor/receptor in order to modulate the loop. A new approach explored in this work is to leverage transport phenomena at cellular resolution to downregulate overall diffusible signaling through the physical removal of cell-secreted ligands. Methodology/Principal Findings We develop a multiplex microfluidic platform to continuously remove cell-secreted (autocrine\\paracrine) factors to downregulate diffusible signaling. By comparing cell growth and differentiation in side-by-side chambers with or without added cell-secreted factors, we isolate the effects of diffusible signaling from artifacts such as shear, nutrient depletion, and microsystem effects, and find that cell-secreted growth factor(s) are required during neuroectodermal specification. Then we induce FGF4 signaling in minimal chemically defined medium (N2B27) and inhibit FGF signaling in fully supplemented differentiation medium with cell-secreted factors to determine that the non-FGF cell-secreted factors are required to promote growth of differentiating mESCs. Conclusions/Significance Our results demonstrate for the first time that flow can downregulate autocrine\\paracrine signaling and examine sufficiency of extracellular factors. We show that autocrine\\paracrine signaling drives neuroectodermal commitment of mESCs through both FGF4-dependent and

  3. OBE3 and WUS Interaction in Shoot Meristem Stem Cell Regulation.

    PubMed

    Lin, Ta-Fang; Saiga, Shunsuke; Abe, Mitsutomo; Laux, Thomas

    2016-01-01

    The stem cells in the shoot apical meristem (SAM) are the origin of all above ground tissues in plants. In Arabidopsis thaliana, shoot meristem stem cells are maintained by the homeobox transcription factor gene WUS (WUSCHEL) that is expressed in cells of the organizing center underneath the stem cells. In order to identify factors that operate together with WUS in stem cell maintenance, we performed an EMS mutant screen for modifiers of the hypomorphic wus-6 allele. We isolated the oberon3-2 (obe3-2) mutant that enhances stem cell defects in wus-6, but does not affect the putative null allele wus-1. The OBE3 gene encodes a PHD (Plant Homeo Domain) protein that is thought to function in chromatin regulation. Single mutants of OBE3 or its closest homolog OBE4 do not display any defects, whereas the obe3-2 obe4-2 double mutant displays broad growth defects and developmental arrest of seedlings. Transcript levels of WUS and its target gene in the stem cells, CLAVATA3, are reduced in obe3-2. On the other hand, OBE3 and OBE4 transcripts are both indirectly upregulated by ectopic WUS expression. Our results suggest a positive feedback regulation between WUS and OBE3 that contributes to shoot meristem homeostasis.

  4. From mechanical stimulation to biological pathways in the regulation of stem cell fate.

    PubMed

    Shah, Nirali; Morsi, Yosry; Manasseh, Richard

    2014-06-01

    Mechanical stimuli are important in directing the fate of stem cells; the effects of mechanical stimuli reported in recent research are reviewed here. Stem cells normally undergo two fundamental processes: proliferation, in which their numbers multiply, and differentiation, in which they transform into the specialized cells needed by the adult organism. Mechanical stimuli are well known to affect both processes of proliferation and differentiation, although the complete pathways relating specific mechanical stimuli to stem cell fate remain to be elucidated. We identified two broad classes of research findings and organized them according to the type of mechanical stress (compressive, tensile or shear) of the stimulus. Firstly, mechanical stress of any type activates stretch-activated channels (SACs) on the cell membrane. Activation of SACs leads to cytoskeletal remodelling and to the expression of genes that regulate the basic growth, survival or apoptosis of the cells and thus regulates proliferation. Secondly, mechanical stress on cells that are physically attached to an extracellular matrix (ECM) initiates remodelling of cell membrane structures called integrins. This second process is highly dependent on the type of mechanical stress applied and result into various biological responses. A further process, the Wnt pathway, is also implicated: crosstalk between the integrin and Wnt pathways regulates the switch from proliferation to differentiation and finally regulates the type of differentiation. Therefore, the stem cell differentiation process involves different signalling molecules and their pathways and most likely depends upon the applied mechanical stimulation. Copyright © 2014 John Wiley & Sons, Ltd.

  5. Monoamine oxidase A regulates neural differentiation of murine embryonic stem cells

    PubMed Central

    Wang, Zhi-qiang; Chen, Kevin; Ying, Qi-long; Li, Ping

    2012-01-01

    Monoamine oxidase (MAO) A is the major metabolizing enzyme of serotonin (5-hydroxytryptamine, 5-HT) which regulates early brain development. In this study, wild-type (WT) and MAO Aneo embryonic stem (ES) cell lines were established from the inner cell mass of murine blastocysts and their characteristics during ES and differentiating stages were studied. Our results show that the differentiation to neural cells in MAO Aneo ES cells was reduced compared to WT, suggesting MAO A played a regulatory role in stem cells neural differentiation. PMID:21607742

  6. Remote Control of Multimodal Nanoscale Ligand Oscillations Regulates Stem Cell Adhesion and Differentiation.

    PubMed

    Kang, Heemin; Wong, Dexter Siu Hong; Yan, Xiaohui; Jung, Hee Joon; Kim, Sungkyu; Lin, Sien; Wei, Kongchang; Li, Gang; Dravid, Vinayak P; Bian, Liming

    2017-08-30

    Cellular adhesion is regulated by the dynamic ligation process of surface receptors, such as integrin, to adhesive motifs, such as Arg-Gly-Asp (RGD). Remote control of adhesive ligand presentation using external stimuli is an appealing strategy for the temporal regulation of cell-implant interactions in vivo and was recently demonstrated using photochemical reaction. However, the limited tissue penetration of light potentially hampers the widespread applications of this method in vivo. Here, we present a strategy for modulating the nanoscale oscillations of an integrin ligand simply and solely by adjusting the frequency of an oscillating magnetic field to regulate the adhesion and differentiation of stem cells. A superparamagnetic iron oxide nanoparticle (SPION) was conjugated with the RGD ligand and anchored to a glass substrate by a long flexible poly(ethylene glycol) linker to allow the oscillatory motion of the ligand to be magnetically tuned. In situ magnetic scanning transmission electron microscopy and atomic force microscopy imaging confirmed the nanoscale motion of the substrate-tethered RGD-grafted SPION. Our findings show that ligand oscillations under a low oscillation frequency (0.1 Hz) of the magnetic field promoted integrin-ligand binding and the formation and maturation of focal adhesions and therefore the substrate adhesion of stem cells, while ligands oscillating under high frequency (2 Hz) inhibited integrin ligation and stem cell adhesion, both in vitro and in vivo. Temporal switching of the multimodal ligand oscillations between low- and high-frequency modes reversibly regulated stem cell adhesion. The ligand oscillations further induced the stem cell differentiation and mechanosensing in the same frequency-dependent manner. Our study demonstrates a noninvasive, penetrative, and tunable approach to regulate cellular responses to biomaterials in vivo. Our work not only provides additional insight into the design considerations of biomaterials to

  7. Harmonizing the international regulation of embryonic stem cell research: possibilities, promises and potential pitfalls.

    PubMed

    Campbell, Angela; Nycum, Gillian

    2005-01-01

    Despite near unanimous global opposition to human reproductive cloning, the United Nations has been unable to reach a consensus as to how cloning practices should be regulated at the international level. As a result, the U.N. objective of establishing binding international regulations governing cloning and stem cell research has yet to be achieved. Given the lack of consensus that exists within the global community on this topic, it seems that any attempt to harmonize the international regulation of cloning and stem cell science will face important obstacles. This paper seeks to illuminate the particular challenges to harmonizing international laws and policies related to stem cell research and human cloning, and to investigate potential methods for overcoming these challenges. By drawing on two other areas in which regulatory harmonization has been attempted, namely: environmental and human safety aspects of international trade, and pharmaceutical research and development, we study approaches to global regulatory harmonization. We conclude that while the challenges to harmonization are diverse and important, so too are the benefits of establishing uniformity in approaches to stem cell research worldwide. This paper proposes a model for harmonizing the regulation of stem cell research that focuses on broader norms and principles rather than specific rules. It further recommends that such harmonization should occur through a process initiated and developed by an independent international agency marked by diversity, both in terms of the cultural identities and perspectives represented, and the interdisciplinary expertise of its members.

  8. Dynamic Trk and G Protein Signalings Regulate Dopaminergic Neurodifferentiation in Human Trophoblast Stem Cells.

    PubMed

    Tsai, Eing-Mei; Wang, Yu-Chih; Lee, Tony Tung-Yin; Tsai, Cheng-Fang; Chen, Hung-Sheng; Lai, Feng-Jie; Yokoyama, Kazunari K; Hsieh, Tsung-Hsun; Wu, Ruey-Meei; Lee, Jau-Nan

    2015-01-01

    Understanding the mechanisms in the generation of neural stem cells from pluripotent stem cells is a fundamental step towards successful management of neurodegenerative diseases in translational medicine. Albeit all-trans retinoic acid (RA) has been associated with axon outgrowth and nerve regeneration, the maintenance of differentiated neurons, the association with degenerative disease like Parkinson's disease, and its regulatory molecular mechanism from pluripotent stem cells to neural stem cells remain fragmented. We have previously reported that RA is capable of differentiation of human trophoblast stem cells to dopamine (DA) committed progenitor cells. Intracranial implantation of such neural progenitor cells into the 6-OHDA-lesioned substantia nigra pars compacta successfully regenerates dopaminergic neurons and integrity of the nigrostriatal pathway, ameliorating the behavioral deficits in the Parkinson's disease rat model. Here, we demonstrated a dynamic molecular network in systematic analysis by addressing spatiotemporal molecular expression, intracellular protein-protein interaction and inhibition, imaging study, and genetic expression to explore the regulatory mechanisms of RA induction in the differentiation of human trophoblast stem cells to DA committed progenitor cells. We focused on the tyrosine receptor kinase (Trk), G proteins, canonical Wnt2B/β-catenin, genomic and non-genomic RA signaling transductions with Tyrosine hydroxylase (TH) gene expression as the differentiation endpoint. We found that at the early stage, integration of TrkA and G protein signalings aims for axonogenesis and morphogenesis, involving the novel RXRα/Gαq/11 and RARβ/Gβ signaling pathways. While at the later stage, five distinct signaling pathways together with epigenetic histone modifications emerged to regulate expression of TH, a precursor of dopamine. RA induction generated DA committed progenitor cells in one day. Our results provided substantial mechanistic

  9. Regulation of spermatogonial stem cell self-renewal and spermatocyte meiosis by Sertoli cell signaling.

    PubMed

    Chen, Su-Ren; Liu, Yi-Xun

    2015-04-01

    Spermatogenesis is a continuous and productive process supported by the self-renewal and differentiation of spermatogonial stem cells (SSCs), which arise from undifferentiated precursors known as gonocytes and are strictly controlled in a special 'niche' microenvironment in the seminiferous tubules. Sertoli cells, the only somatic cell type in the tubules, directly interact with SSCs to control their proliferation and differentiation through the secretion of specific factors. Spermatocyte meiosis is another key step of spermatogenesis, which is regulated by Sertoli cells on the luminal side of the blood-testis barrier through paracrine signaling. In this review, we mainly focus on the role of Sertoli cells in the regulation of SSC self-renewal and spermatocyte meiosis, with particular emphasis on paracrine and endocrine-mediated signaling pathways. Sertoli cell growth factors, such as glial cell line-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2), as well as Sertoli cell transcription factors, such as ETS variant 5 (ERM; also known as ETV5), nociceptin, neuregulin 1 (NRG1), and androgen receptor (AR), have been identified as the most important upstream factors that regulate SSC self-renewal and spermatocyte meiosis. Other transcription factors and signaling pathways (GDNF-RET-GFRA1 signaling, FGF2-MAP2K1 signaling, CXCL12-CXCR4 signaling, CCL9-CCR1 signaling, FSH-nociceptin/OPRL1, retinoic acid/FSH-NRG/ERBB4, and AR/RB-ARID4A/ARID4B) are also addressed.

  10. The transcriptional regulator lola is required for stem cell maintenance and germ cell differentiation in the Drosophila testis

    PubMed Central

    Davies, Erin L.; Lim, Jaclyn G.Y.; Joo, William J.; Tam, Cheuk Ho; Fuller, Margaret T.

    2014-01-01

    Stem cell behavior is regulated by extrinsic signals from specialized microenvironments, or niches, and intrinsic factors required for execution of context-appropriate responses to niche signals. Here we show that function of the transcriptional regulator longitudinals lacking (lola) is required cell autonomously for germline stem cell and somatic cyst stem cell maintenance in the Drosophila testis. In addition, lola is also required for proper execution of key developmental transitions during male germ cell differentiation, including the switch from transit amplifying progenitor to spermatocyte growth and differentiation, as well as meiotic cell cycle progression and spermiogenesis. Different lola isoforms, each having unique C-termini and zinc finger domains, may control different aspects of proliferation and differentiation in the male germline and somatic cyst stem cell lineages. PMID:23159836

  11. Orphan nuclear receptor TLX recruits histone deacetylases to repress transcription and regulate neural stem cell proliferation

    PubMed Central

    Sun, GuoQiang; Yu, Ruth T.; Evans, Ronald M.; Shi, Yanhong

    2007-01-01

    TLX is a transcription factor that is essential for neural stem cell proliferation and self-renewal. However, the molecular mechanism of TLX-mediated neural stem cell proliferation and self-renewal is largely unknown. We show here that TLX recruits histone deacetylases (HDACs) to its downstream target genes to repress their transcription, which in turn regulates neural stem cell proliferation. TLX interacts with HDAC3 and HDAC5 in neural stem cells. The HDAC5-interaction domain was mapped to TLX residues 359–385, which contains a conserved nuclear receptor–coregulator interaction motif IXXLL. Both HDAC3 and HDAC5 have been shown to be recruited to the promoters of TLX target genes along with TLX in neural stem cells. Recruitment of HDACs led to transcriptional repression of TLX target genes, the cyclin-dependent kinase inhibitor, p21CIP1/WAF1(p21), and the tumor suppressor gene, pten. Either inhibition of HDAC activity or knockdown of HDAC expression led to marked induction of p21 and pten gene expression and dramatically reduced neural stem cell proliferation, suggesting that the TLX-interacting HDACs play an important role in neural stem cell proliferation. Moreover, expression of a TLX peptide containing the minimal HDAC5 interaction domain disrupted the TLX–HDAC5 interaction. Disruption of this interaction led to significant induction of p21 and pten gene expression and to dramatic inhibition of neural stem cell proliferation. Taken together, these findings demonstrate a mechanism for neural stem cell proliferation through transcriptional repression of p21 and pten gene expression by TLX–HDAC interactions. PMID:17873065

  12. Regulation of crucial lncRNAs in differentiation of chicken embryonic stem cells to spermatogonia stem cells.

    PubMed

    Li, D; Ji, Y; Wang, F; Wang, Y; Wang, M; Zhang, C; Zhang, W; Lu, Z; Sun, C; Ahmed, M F; He, N; Jin, K; Cheng, S; Wang, Y; He, Y; Song, J; Zhang, Y; Li, B

    2017-04-01

    Regulation of crucial lncRNAs involved in differentiation of chicken embryonic stem cells (ESCs) to spermatogonia stem cells (SSCs) was explored by sequencing the transcriptome of ESCs, primordial germ cells (PGCs) and SSCs with RNA-Seq; analytical bioinformatic methods were used to excavate candidate lncRNAs. We detected expression of candidate lncRNAs in ESCs, PGCs and SSCs and forecasted related target genes. Utilizing wego, david and string, function and protein-protein interactions of target genes were analyzed. Finally, based on string analysis, interaction diagrams and relevant signaling pathways were established. Our results indicate a total of 9657 lncRNAs in ESCs, PGCs and SSCs, with 3549 defined as significantly different. We screened 20 candidate lncRNAs, each demonstrating a greater than eight-fold difference in |logFC| value between groups (ESCs vs. PGCs, ESCs vs. SSCs and PGCs vs. SSCs) or specifically expressed in an individual cell type. qRT-PCR results indicated that expression tendencies of candidate lncRNAs were consistent with RNA-Seq. Fifteen cis and four trans target genes were forecasted. Based on wego and string analyses, we found lnc-SSC1, lnc-SSC5, lnc-SSC2 and lnc-ESC2 negatively regulated target genes SUFU, EPHA3, KLF3, ARL3 and TRIM8, whereas SHH, NOTCH, TGF-β, cAMP/cGMP and JAK/STAT signaling pathways were promoted, causing differentiation of ESCs into SSCs. Our findings represent a preliminary unveiling of lncRNA-associated regulatory mechanisms during differentiation of chicken ESCs into SSCs, filling a research void in male germ cell differentiation related to lncRNA. Our results also provide basic information for improving in vitro induction systems for differentiation of chicken ESCs into SSCs.

  13. Proximity-Based Differential Single-Cell Analysis of the Niche to Identify Stem/Progenitor Cell Regulators.

    PubMed

    Silberstein, Lev; Goncalves, Kevin A; Kharchenko, Peter V; Turcotte, Raphael; Kfoury, Youmna; Mercier, Francois; Baryawno, Ninib; Severe, Nicolas; Bachand, Jacqueline; Spencer, Joel A; Papazian, Ani; Lee, Dongjun; Chitteti, Brahmananda Reddy; Srour, Edward F; Hoggatt, Jonathan; Tate, Tiffany; Lo Celso, Cristina; Ono, Noriaki; Nutt, Stephen; Heino, Jyrki; Sipilä, Kalle; Shioda, Toshihiro; Osawa, Masatake; Lin, Charles P; Hu, Guo-Fu; Scadden, David T

    2016-10-06

    Physiological stem cell function is regulated by secreted factors produced by niche cells. In this study, we describe an unbiased approach based on the differential single-cell gene expression analysis of mesenchymal osteolineage cells close to, and further removed from, hematopoietic stem/progenitor cells (HSPCs) to identify candidate niche factors. Mesenchymal cells displayed distinct molecular profiles based on their relative location. We functionally examined, among the genes that were preferentially expressed in proximal cells, three secreted or cell-surface molecules not previously connected to HSPC biology-the secreted RNase angiogenin, the cytokine IL18, and the adhesion molecule Embigin-and discovered that all of these factors are HSPC quiescence regulators. Therefore, our proximity-based differential single-cell approach reveals molecular heterogeneity within niche cells and can be used to identify novel extrinsic stem/progenitor cell regulators. Similar approaches could also be applied to other stem cell/niche pairs to advance the understanding of microenvironmental regulation of stem cell function. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Proximity-based differential single cell analysis of the niche to identify stem/progenitor cell regulators

    PubMed Central

    Silberstein, Lev; Goncalves, Kevin A; Kharchenko, Peter V; Turcotte, Raphael; Kfoury, Youmna; Mercier, Francois; Baryawno, Ninib; Severe, Nicolas; Bachand, Jacqueline; Spencer, Joel; Papazian, Ani; Lee, Dongjun; Chitteti, Brahmananda Reddy; Srour, Edward F; Hoggatt, Jonathan; Tate, Tiffany; Celso, Cristina Lo; Ono, Noriaki; Nutt, Stephen; Heino, Jyrki; Sipilä, Kalle; Shioda, Toshihiro; Osawa, Masatake; Lin, Charles P; Hu, Guo-fu; Scadden, David T

    2016-01-01

    SUMMARY Physiological stem cell function is regulated by secreted factors produced by niche cells. In this study, we describe an unbiased approach based on differential single-cell gene expression analysis of mesenchymal osteolineage cells close to and further removed from hematopoietic stem/progenitor cells to identify candidate niche factors. Mesenchymal cells displayed distinct molecular profiles based on their relative location. Amongst the genes which were preferentially expressed in proximal cells, we functionally examined three secreted or cell surface molecules not previously connected to HSPC biology: the secreted RNase Angiogenin, the cytokine IL18 and the adhesion molecule Embigin and discovered that all of these factors are HSPC quiescence regulators. Our proximity-based differential single cell approach therefore reveals molecular heterogeneity within niche cells and can be used to identify novel extrinsic stem/progenitor cell regulators. Similar approaches could also be applied to other stem cell/niche pairs to advance understanding of microenvironmental regulation of stem cell function. PMID:27524439

  15. Progressive Chromatin Condensation and H3K9 Methylation Regulate the Differentiation of Embryonic and Hematopoietic Stem Cells

    DOE PAGES

    Ugarte, Fernando; Sousae, Rebekah; Cinquin, Bertrand; ...

    2015-10-17

    Epigenetic regulation serves as the basis for stem cell differentiation into distinct cell types, but it is unclear how global epigenetic changes are regulated during this process. Here, we tested the hypothesis that global chromatin organization affects the lineage potential of stem cells and that manipulation of chromatin dynamics influences stem cell function. Using nuclease sensitivity assays, we found a progressive decrease in chromatin digestion among pluripotent embryonic stem cells (ESCs), multipotent hematopoietic stem cells (HSCs), and mature hematopoietic cells. Quantitative high-resolution microscopy revealed that ESCs contain significantly more euchromatin than HSCs, with a further reduction in mature cells. Increasedmore » cellular maturation also led to heterochromatin localization to the nuclear periphery. Functionally, prevention of heterochromatin formation by inhibition of the histone methyltransferase G9A resulted in delayed HSC differentiation. Lastly, our results demonstrate global chromatin rearrangements during stem cell differentiation and that heterochromatin formation by H3K9 methylation regulates HSC differentiation.« less

  16. Progressive Chromatin Condensation and H3K9 Methylation Regulate the Differentiation of Embryonic and Hematopoietic Stem Cells

    PubMed Central

    Ugarte, Fernando; Sousae, Rebekah; Cinquin, Bertrand; Martin, Eric W.; Krietsch, Jana; Sanchez, Gabriela; Inman, Margaux; Tsang, Herman; Warr, Matthew; Passegué, Emmanuelle; Larabell, Carolyn A.; Forsberg, E. Camilla

    2015-01-01

    Summary Epigenetic regulation serves as the basis for stem cell differentiation into distinct cell types, but it is unclear how global epigenetic changes are regulated during this process. Here, we tested the hypothesis that global chromatin organization affects the lineage potential of stem cells and that manipulation of chromatin dynamics influences stem cell function. Using nuclease sensitivity assays, we found a progressive decrease in chromatin digestion among pluripotent embryonic stem cells (ESCs), multipotent hematopoietic stem cells (HSCs), and mature hematopoietic cells. Quantitative high-resolution microscopy revealed that ESCs contain significantly more euchromatin than HSCs, with a further reduction in mature cells. Increased cellular maturation also led to heterochromatin localization to the nuclear periphery. Functionally, prevention of heterochromatin formation by inhibition of the histone methyltransferase G9A resulted in delayed HSC differentiation. Our results demonstrate global chromatin rearrangements during stem cell differentiation and that heterochromatin formation by H3K9 methylation regulates HSC differentiation. PMID:26489895

  17. FoxO is a critical regulator of stem cell maintenance in immortal Hydra

    PubMed Central

    Boehm, Anna-Marei; Khalturin, Konstantin; Anton-Erxleben, Friederike; Hemmrich, Georg; Klostermeier, Ulrich C.; Lopez-Quintero, Javier A.; Oberg, Hans-Heinrich; Puchert, Malte; Rosenstiel, Philip; Wittlieb, Jörg; Bosch, Thomas C. G.

    2012-01-01

    Hydra’s unlimited life span has long attracted attention from natural scientists. The reason for that phenomenon is the indefinite self-renewal capacity of its stem cells. The underlying molecular mechanisms have yet to be explored. Here, by comparing the transcriptomes of Hydra’s stem cells followed by functional analysis using transgenic polyps, we identified the transcription factor forkhead box O (FoxO) as one of the critical drivers of this continuous self-renewal. foxO overexpression increased interstitial stem cell and progenitor cell proliferation and activated stem cell genes in terminally differentiated somatic cells. foxO down-regulation led to an increase in the number of terminally differentiated cells, resulting in a drastically reduced population growth rate. In addition, it caused down-regulation of stem cell genes and antimicrobial peptide (AMP) expression. These findings contribute to a molecular understanding of Hydra’s immortality, indicate an evolutionarily conserved role of FoxO in controlling longevity from Hydra to humans, and have implications for understanding cellular aging. PMID:23150562

  18. Post-transcriptional regulation of gene expression in neural stem cells.

    PubMed

    Kim, Do-Yeon

    2016-06-01

    Expression of each gene can be controlled at several steps during the flow of genetic information from DNA to protein. Tight regulation of gene expression is especially important for stem cells because of their greater ripple effects, compared with terminally differentiated cells. Dysregulation of gene expression arising in stem cells can be perpetuated within the stem cell pool via self-renewal throughout life. In addition, transcript profiles within stem cells can determine the selective advantage or disadvantage of each cell, leading to changes in cell fate, such as a tendency for proliferation, death, and differentiation. The identification of neural stem/progenitor cells (NSPCs) and greater understanding of their cellular physiology have raised the possibility of using NSPCs to replace damaged or injured neurons. However, an accurate grasp of gene expression control must take precedence in order to use NSPCs in therapies for neurological diseases. Recently, accumulating evidence has demonstrated the importance of post-transcriptional regulation in NSPC fate decisions. In this review, we will summarize and discuss the recent findings on key mRNA modulators and their vital roles in NSPC homeostasis. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Zeb2 Regulates Cell Fate at the Exit from Epiblast State in Mouse Embryonic Stem Cells.

    PubMed

    Stryjewska, Agata; Dries, Ruben; Pieters, Tim; Verstappen, Griet; Conidi, Andrea; Coddens, Kathleen; Francis, Annick; Umans, Lieve; van IJcken, Wilfred F J; Berx, Geert; van Grunsven, Leo A; Grosveld, Frank G; Goossens, Steven; Haigh, Jody J; Huylebroeck, Danny

    2017-03-01

    In human embryonic stem cells (ESCs) the transcription factor Zeb2 regulates neuroectoderm versus mesendoderm formation, but it is unclear how Zeb2 affects the global transcriptional regulatory network in these cell-fate decisions. We generated Zeb2 knockout (KO) mouse ESCs, subjected them as embryoid bodies (EBs) to neural and general differentiation and carried out temporal RNA-sequencing (RNA-seq) and reduced representation bisulfite sequencing (RRBS) analysis in neural differentiation. This shows that Zeb2 acts preferentially as a transcriptional repressor associated with developmental progression and that Zeb2 KO ESCs can exit from their naïve state. However, most cells in these EBs stall in an early epiblast-like state and are impaired in both neural and mesendodermal differentiation. Genes involved in pluripotency, epithelial-to-mesenchymal transition (EMT), and DNA-(de)methylation, including Tet1, are deregulated in the absence of Zeb2. The observed elevated Tet1 levels in the mutant cells and the knowledge of previously mapped Tet1-binding sites correlate with loss-of-methylation in neural-stimulating conditions, however, after the cells initially acquired the correct DNA-methyl marks. Interestingly, cells from such Zeb2 KO EBs maintain the ability to re-adapt to 2i + LIF conditions even after prolonged differentiation, while knockdown of Tet1 partially rescues their impaired differentiation. Hence, in addition to its role in EMT, Zeb2 is critical in ESCs for exit from the epiblast state, and links the pluripotency network and DNA-methylation with irreversible commitment to differentiation. Stem Cells 2017;35:611-625. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

  20. Dynamic regulation of the cancer stem cell compartment by Cripto-1 in colorectal cancer

    PubMed Central

    Francescangeli, F; Contavalli, P; De Angelis, M L; Baiocchi, M; Gambara, G; Pagliuca, A; Fiorenzano, A; Prezioso, C; Boe, A; Todaro, M; Stassi, G; Castro, N P; Watanabe, K; Salomon, D S; De Maria, R; Minchiotti, G; Zeuner, A

    2015-01-01

    Stemness was recently depicted as a dynamic condition in normal and tumor cells. We found that the embryonic protein Cripto-1 (CR1) was expressed by normal stem cells at the bottom of colonic crypts and by cancer stem cells (CSCs) in colorectal tumor tissues. CR1-positive populations isolated from patient-derived tumor spheroids exhibited increased clonogenic capacity and expression of stem-cell-related genes. CR1 expression in tumor spheroids was variable over time, being subject to a complex regulation of the intracellular, surface and secreted protein, which was related to changes of the clonogenic capacity at the population level. CR1 silencing induced CSC growth arrest in vitro with a concomitant decrease of Src/Akt signaling, while in vivo it inhibited the growth of CSC-derived tumor xenografts and reduced CSC numbers. Importantly, CR1 silencing in established xenografts through an inducible expression system decreased CSC growth in both primary and metastatic tumors, indicating an essential role of CR1 in the regulation the CSC compartment. These results point to CR1 as a novel and dynamically regulated effector of stem cell functions in colorectal cancer. PMID:26343543

  1. B-myb is an essential regulator of hematopoietic stem cell and myeloid progenitor cell development

    PubMed Central

    Baker, Stacey J.; Ma’ayan, Avi; Lieu, Yen K.; John, Premila; Reddy, M. V. Ramana; Chen, Edward Y.; Duan, Qiaonan; Snoeck, Hans-Willem; Reddy, E. Premkumar

    2014-01-01

    The B-myb (MYBL2) gene is a member of the MYB family of transcription factors and is involved in cell cycle regulation, DNA replication, and maintenance of genomic integrity. However, its function during adult development and hematopoiesis is unknown. We show here that conditional inactivation of B-myb in vivo results in depletion of the hematopoietic stem cell (HSC) pool, leading to profound reductions in mature lymphoid, erythroid, and myeloid cells. This defect is autonomous to the bone marrow and is first evident in stem cells, which accumulate in the S and G2/M phases. B-myb inactivation also causes defects in the myeloid progenitor compartment, consisting of depletion of common myeloid progenitors but relative sparing of granulocyte–macrophage progenitors. Microarray studies indicate that B-myb–null LSK+ cells differentially express genes that direct myeloid lineage development and commitment, suggesting that B-myb is a key player in controlling cell fate. Collectively, these studies demonstrate that B-myb is essential for HSC and progenitor maintenance and survival during hematopoiesis. PMID:24516162

  2. B-myb is an essential regulator of hematopoietic stem cell and myeloid progenitor cell development.

    PubMed

    Baker, Stacey J; Ma'ayan, Avi; Lieu, Yen K; John, Premila; Reddy, M V Ramana; Chen, Edward Y; Duan, Qiaonan; Snoeck, Hans-Willem; Reddy, E Premkumar

    2014-02-25

    The B-myb (MYBL2) gene is a member of the MYB family of transcription factors and is involved in cell cycle regulation, DNA replication, and maintenance of genomic integrity. However, its function during adult development and hematopoiesis is unknown. We show here that conditional inactivation of B-myb in vivo results in depletion of the hematopoietic stem cell (HSC) pool, leading to profound reductions in mature lymphoid, erythroid, and myeloid cells. This defect is autonomous to the bone marrow and is first evident in stem cells, which accumulate in the S and G2/M phases. B-myb inactivation also causes defects in the myeloid progenitor compartment, consisting of depletion of common myeloid progenitors but relative sparing of granulocyte-macrophage progenitors. Microarray studies indicate that B-myb-null LSK(+) cells differentially express genes that direct myeloid lineage development and commitment, suggesting that B-myb is a key player in controlling cell fate. Collectively, these studies demonstrate that B-myb is essential for HSC and progenitor maintenance and survival during hematopoiesis.

  3. SOX10 induced Nestin expression regulates cancer stem cell properties of TNBC cells.

    PubMed

    Feng, Wen; Liu, Sihai; Zhu, Ruixia; Li, Baojian; Zhu, Zhu; Yang, Jinshan; Song, Chunhui

    2017-04-01

    The mechanisms modulating the cancer stem cell (CSC) properties of triple negative breast cancer (TNBC) cells were not fully understood. In this study, we performed data mining in Breast Cancer Gene-Expression Miner v4.0 and found that TNBC tumors had significantly higher NES mRNA expression than other breast cancer subtypes. Pooled data suggested that NES mRNA expression is associated worse metastatic relapse (MR) free survival and also worse any event (AE) free survival in TNBC patients. Following data mining in multiple big data databases confirmed a positive correlation between SOX10 mRNA expression and NES mRNA expression in breast cancer tissues. In addition, the expression of SOX10 mRNA is significantly higher in TNBC tissues than in other breast cancer subtypes. SOX10 overexpression resulted in Nestin upregulation at both mRNA and protein levels. Bioinformatic analysis predicted a SOX10 binding site in NES promoter and the following dual luciferase assay verified the binding site. Functionally, SOX10 overexpression substantially increased CSC properties of TNBC cells, while SOX10 knockdown decreased the CSC properties, in terms of CD24(-)/CD44(+) cell ratio and tumorsphere-forming capabilities. Enforced Nestin expression partly counteracted the effect of SOX10 knockdown on reducing the CSC properties. Based on these findings, we infer that SOX10 regulates cancer stem cell properties of TNBC cells via inducing Nestin expression.

  4. Piwi Is a Key Regulator of Both Somatic and Germline Stem Cells in the Drosophila Testis.

    PubMed

    Gonzalez, Jacob; Qi, Hongying; Liu, Na; Lin, Haifan

    2015-07-07

    The Piwi-piRNA pathway is well known for its germline function, yet its somatic role remains elusive. We show here that Piwi is required autonomously not only for germline stem cell (GSC) but also for somatic cyst stem cell (CySC) maintenance in the Drosophila testis. Reducing Piwi activity in the testis caused defects in CySC differentiation. Accompanying this, GSC daughters expanded beyond the vicinity of the hub but failed to differentiate further. Moreover, Piwi deficient in nuclear localization caused similar defects in somatic and germ cell differentiation, which was rescued by somatic Piwi expression. To explore the underlying molecular mechanism, we identified Piwi-bound piRNAs that uniquely map to a gene key for gonadal development, Fasciclin 3, and demonstrate that Piwi regulates its expression in somatic cyst cells. Our work reveals the cell-autonomous function of Piwi in both somatic and germline stem cell types, with somatic function possibly via its epigenetic mechanism.

  5. p107 is a crucial regulator for determining the adipocyte lineage fate choices of stem cells.

    PubMed

    De Sousa, Martina; Porras, Deanna P; Perry, Christopher G R; Seale, Patrick; Scimè, Anthony

    2014-05-01

    Thermogenic (beige and brown) adipocytes protect animals against obesity and metabolic disease. However, little is known about the mechanisms that commit stem cells toward different adipocyte lineages. We show here that p107 is a master regulator of adipocyte lineage fates, its suppression required for commitment of stem cells to the brown-type fate. p107 is strictly expressed in the stem cell compartment of white adipose tissue depots and completely absent in brown adipose tissue. Remarkably, p107-deficient stem cells uniformly give rise to brown-type adipocytes in vitro and in vivo. Furthermore, brown fat programming of mesenchymal stem cells by PRDM-BF1-RIZ1 homologous domain containing 16 (Prdm16) was associated with a dramatic reduction of p107 levels. Indeed, Prdm16 directly suppressed p107 transcription via promoter binding. Notably, the sustained expression of p107 blocked the ability of Prdm16 to induce brown fat genes. These findings demonstrate that p107 expression in stem cells commits cells to the white versus brown adipose lineage. © 2014 AlphaMed Press.

  6. A Temporal Chromatin Signature in Human Embryonic Stem Cells Identifies Regulators of Cardiac Development

    PubMed Central

    Paige, Sharon L.; Thomas, Sean; Stoick-Cooper, Cristi L.; Wang, Hao; Maves, Lisa; Sandstrom, Richard; Pabon, Lil; Reinecke, Hans; Pratt, Gabriel; Keller, Gordon; Moon, Randall T.; Stamatoyannopoulos, John; Murry, Charles E.

    2012-01-01

    Summary Directed differentiation of human embryonic stem cells (ESCs) into cardiovascular cells provides a model for studying molecular mechanisms of human cardiovascular development. Though it is known that chromatin modification patterns in ESCs differ markedly from those in lineage-committed progenitors and differentiated cells, the temporal dynamics of chromatin alterations during differentiation along a defined lineage have not been studied. We show that differentiation of human ESCs into cardiovascular cells is accompanied by programmed temporal alterations in chromatin structure that distinguish key regulators of cardiovascular development from other genes. We used this temporal chromatin signature to identify regulators of cardiac development, including the homeobox gene MEIS2. We demonstrate using the zebrafish model that MEIS2 is critical for proper heart tube formation and subsequent cardiac looping. Temporal chromatin signatures should be broadly applicable to other models of stem cell differentiation to identify regulators and provide key insights into major developmental decisions. PMID:22981225

  7. Live imaging of the Drosophila spermatogonial stem cell niche reveals novel mechanisms regulating germline stem cell output.

    PubMed

    Sheng, X Rebecca; Matunis, Erika

    2011-08-01

    Adult stem cells modulate their output by varying between symmetric and asymmetric divisions, but have rarely been observed in living intact tissues. Germline stem cells (GSCs) in the Drosophila testis are anchored to somatic hub cells and were thought to exclusively undergo oriented asymmetric divisions, producing one stem cell that remains hub-anchored and one daughter cell displaced out of the stem cell-maintaining micro-environment (niche). We developed extended live imaging of the Drosophila testis niche, allowing us to track individual germline cells. Surprisingly, new wild-type GSCs are generated in the niche during steady-state tissue maintenance by a previously undetected event we term 'symmetric renewal', where interconnected GSC-daughter cell pairs swivel such that both cells contact the hub. We also captured GSCs undergoing direct differentiation by detaching from the hub. Following starvation-induced GSC loss, GSC numbers are restored by symmetric renewals. Furthermore, upon more severe (genetically induced) GSC loss, both symmetric renewal and de-differentiation (where interconnected spermatogonia fragment into pairs while moving towards then establishing contact with the hub) occur simultaneously to replenish the GSC pool. Thus, stereotypically oriented stem cell divisions are not always correlated with an asymmetric outcome in cell fate, and changes in stem cell output are governed by altered signals in response to tissue requirements.

  8. Dynamic changes in intracellular ROS levels regulate airway basal stem cell homeostasis through Nrf2-dependent Notch signaling.

    PubMed

    Paul, Manash K; Bisht, Bharti; Darmawan, Daphne O; Chiou, Richard; Ha, Vi L; Wallace, William D; Chon, Andrew T; Hegab, Ahmed E; Grogan, Tristan; Elashoff, David A; Alva-Ornelas, Jackelyn A; Gomperts, Brigitte N

    2014-08-07

    Airways are exposed to myriad environmental and damaging agents such as reactive oxygen species (ROS), which also have physiological roles as signaling molecules that regulate stem cell function. However, the functional significance of both steady and dynamically changing ROS levels in different stem cell populations, as well as downstream mechanisms that integrate ROS sensing into decisions regarding stem cell homeostasis, are unclear. Here, we show in mouse and human airway basal stem cells (ABSCs) that intracellular flux from low to moderate ROS levels is required for stem cell self-renewal and proliferation. Changing ROS levels activate Nrf2, which activates the Notch pathway to stimulate ABSC self-renewal and an antioxidant program that scavenges intracellular ROS, returning overall ROS levels to a low state to maintain homeostatic balance. This redox-mediated regulation of lung stem cell function has significant implications for stem cell biology, repair of lung injuries, and diseases such as cancer.

  9. Differential regulation of stiffness, topography, and dimension of substrates in rat mesenchymal stem cells.

    PubMed

    Li, Zhan; Gong, Yuanwei; Sun, Shujin; Du, Yu; Lü, Dongyuan; Liu, Xiaofeng; Long, Mian

    2013-10-01

    The physiological microenvironment of the stem cell niche, including the three factors of stiffness, topography, and dimension, is crucial to stem cell proliferation and differentiation. Although a growing body of evidence is present to elucidate the importance of these factors individually, the interaction of the biophysical parameters of the factors remains insufficiently characterized, particularly for stem cells. To address this issue fully, we applied a micro-fabricated polyacrylamide hydrogel substrate with two elasticities, two topographies, and three dimensions to systematically test proliferation, morphology and spreading, differentiation, and cytoskeletal re-organization of rat bone marrow mesenchymal stem cells (rBMSCs) on twelve cases. An isolated but not combinatory impact of the factors was found regarding the specific functions. Substrate stiffness or dimension is predominant in regulating cell proliferation by fostering cell growth on stiff, unevenly dimensioned substrate. Topography is a key factor for manipulating cell morphology and spreading via the formation of a large spherical shape in a pillar substrate but not in a grooved substrate. Although stiffness leads to osteogenic or neuronal differentiation of rBMSCs on a stiff or soft substrate, respectively, topography or dimension also plays a lesser role in directing cell differentiation. Neither an isolated effect nor a combinatory effect was found for actin or tubulin expression, whereas a seemingly combinatory effect of topography and dimension was found in manipulating vimentin expression. These results further the understandings of stem cell proliferation, morphology, and differentiation in a physiologically mimicking microenvironment.

  10. The regulation of human embryo and stem-cell research in the United Kingdom.

    PubMed

    Lovell-Badge, Robin

    2008-12-01

    In the United Kingdom, the derivation of human embryonic stem (ES) cells falls under the 1990 Human Fertilisation and Embryology (HFE) Act and subsequent amendments that were adopted in 2001. These laws do not regulate research with ES cells, which follows specific national guidelines. Owing to rapid progress in science and to changes in legal and public opinion, the current British Government proposed further radical amendments in a new HFE Bill. These will have important consequences for research and clinical practice that involve both embryos and stem cells.

  11. Peroxiredoxin II Is Essential for Maintaining Stemness by Redox Regulation in Liver Cancer Cells.

    PubMed

    Kwon, Taeho; Bak, Yesol; Park, Young-Ho; Jang, Gyu-Beom; Nam, Jeong-Seok; Yoo, Jeong Eun; Park, Young Nyun; Bak, In Seon; Kim, Jin-Man; Yoon, Do-Young; Yu, Dae-Yeul

    2016-05-01

    Redox regulation in cancer stem cells (CSCs) is viewed as a good target for cancer therapy because redox status plays an important role in cancer stem-cell maintenance. Here, we investigated the role of Peroxiredoxin II (Prx II), an antioxidant enzyme, in association with maintenance of liver CSCs. Our study demonstrates that Prx II overexpressed in liver cancer cells has high potential for self-renewal activity. Prx II expression significantly corelated with expression of epithelial-cell adhesion molecules (EpCAM) and cytokerain 19 in liver cancer tissues of hepatocellular carcinoma (HCC) patients. Downregulation of Prx II in Huh7 cells with treatment of siRNA reduced expression of EpCAM and CD133 as well as Sox2 in accordance with increased ROS and apoptosis, which were reversed in Huh7-hPrx II cells. Huh7-hPrx II cells exhibited strong sphere-formation activity compared with mock cells. Vascular endothelial growth factor (VEGF) exposure enhanced sphere formation, cell-surface expression of EpCAM and CD133, and pSTAT3 along with activation of VEGF receptor 2 in Huh7-hPrx II cells. The result also emerged in Huh7-H-ras(G12V) and SK-HEP-1-H-ras(G12V) cells with high-level expression of Prx II. Prx II was involved in regulation of VEGF driving cancer stem cells through VEGFR-2/STAT3 signaling to upregulate Bmi1 and Sox2. In addition, knockdown of Prx II in Huh7-H-ras(G12V) cells showed significant reduction in cell migration in vitro and in tumorigenic potential in vivo. Taken together, all the results demonstrated that Prx II plays a key role in the CSC self-renewal of HCC cells through redox regulation. Stem Cells 2016;34:1188-1197.

  12. MYB75 functions in regulation of secondary cell wall formation in the Arabidopsis inflorescence stem.

    PubMed

    Bhargava, Apurva; Mansfield, Shawn D; Hall, Hardy C; Douglas, Carl J; Ellis, Brian E

    2010-11-01

    Deposition of lignified secondary cell walls in plants involves a major commitment of carbon skeletons in both the form of polysaccharides and phenylpropanoid constituents. This process is spatially and temporally regulated by transcription factors, including a number of MYB family transcription factors. MYB75, also called PRODUCTION OF ANTHOCYANIN PIGMENT1, is a known regulator of the anthocyanin branch of the phenylpropanoid pathway in Arabidopsis (Arabidopsis thaliana), but how this regulation might impact other aspects of carbon metabolism is unclear. We established that a loss-of-function mutation in MYB75 (myb75-1) results in increased cell wall thickness in xylary and interfascicular fibers within the inflorescence stem. The total lignin content and S/G ratio of the lignin monomers were also affected. Transcript profiles from the myb75-1 inflorescence stem revealed marked up-regulation in the expression of a suite of genes associated with lignin biosynthesis and cellulose deposition, as well as cell wall modifying proteins and genes involved in photosynthesis and carbon assimilation. These patterns suggest that MYB75 acts as a repressor of the lignin branch of the phenylpropanoid pathway. Since MYB75 physically interacts with another secondary cell wall regulator, the KNOX transcription factor KNAT7, these regulatory proteins may form functional complexes that contribute to the regulation of secondary cell wall deposition in the Arabidopsis inflorescence stem and that integrate the metabolic flux through the lignin, flavonoid, and polysaccharide pathways.

  13. Regulation of Boundary Cap Neural Crest Stem Cell Differentiation After Transplantation

    PubMed Central

    Aldskogius, Hakan; Berens, Christian; Kanaykina, Nadezda; Liakhovitskaia, Anna; Medvinsky, Alexander; Sandelin, Martin; Schreiner, Silke; Wegner, Michael; Hjerling-Leffler, Jens; Kozlova, Elena N

    2009-01-01

    Success of cell replacement therapies for neurological disorders will depend largely on the optimization of strategies to enhance viability and control the developmental fate of stem cells after transplantation. Once transplanted, stem/progenitor cells display a tendency to maintain an undifferentiated phenotype or differentiate into inappropriate cell types. Gain and loss of function experiments have revealed key transcription factors which drive differentiation of immature stem/progenitor cells toward more mature stages and eventually to full differentiation. An attractive course of action to promote survival and direct the differentiation of transplanted stem cells to a specific cell type would therefore be to force expression of regulatory differentiation molecules in already transplanted stem cells, using inducible gene expression systems which can be controlled from the outside. Here, we explore this hypothesis by employing a tetracycline gene regulating system (Tet-On) to drive the differentiation of boundary cap neural crest stem cells (bNCSCs) toward a sensory neuron fate after transplantation. We induced the expression of the key transcription factor Runx1 in Sox10-expressing bNCSCs. Forced expression of Runx1 strongly increased transplant survival in the enriched neurotrophic environment of the dorsal root ganglion cavity, and was sufficient to guide differentiation of bNCSCs toward a nonpeptidergic nociceptive sensory neuron phenotype both in vitro and in vivo after transplantation. These findings suggest that exogenous activation of transcription factors expression after transplantation in stem/progenitor cell grafts can be a constructive approach to control their survival as well as their differentiation to the desired type of cell and that the Tet-system is a useful tool to achieve this. PMID:19544468

  14. Cell cycle regulation by MicroRNAs in embryonic stem cells.

    PubMed

    Wang, Yangming; Blelloch, Robert

    2009-05-15

    The cell cycle is tightly orchestrated during normal development. Embryonic stem (ES) cells have a unique cell cycle structure, in which the G1/S restriction is largely absent, enabling cells to rapidly move through the G1 phase and enter the S phase. This hastened cell cycle allows the early embryo to rapidly grow. Recent experiments suggest that small noncoding RNAs, the microRNAs (miRNAs), play a central role in achieving this unique cell cycle structure. The responsible miRNAs function by suppressing multiple inhibitors of the G1/S transition. Expression of these miRNAs drops dramatically as the ES cells differentiate and as the G1 phase extends. Some of the same miRNAs are overexpressed in cancers, in which they can promote tumor growth, suggesting common mechanisms of miRNA-regulated cell cycle control in ES cells and cancers. This review discusses these recent findings in the context of broader knowledge of cell cycle control in normal and abnormal development.

  15. Whole-animal genome-wide RNAi screen identifies networks regulating male germline stem cells in Drosophila

    PubMed Central

    Liu, Ying; Ge, Qinglan; Chan, Brian; Liu, Hanhan; Singh, Shree Ram; Manley, Jacob; Lee, Jae; Weideman, Ann Marie; Hou, Gerald; Hou, Steven X.

    2016-01-01

    Stem cells are regulated both intrinsically and externally, including by signals from the local environment and distant organs. To identify genes and pathways that regulate stem-cell fates in the whole organism, we perform a genome-wide transgenic RNAi screen through ubiquitous gene knockdowns, focusing on regulators of adult Drosophila testis germline stem cells (GSCs). Here we identify 530 genes that regulate GSC maintenance and differentiation. Of these, we further knock down 113 selected genes using cell-type-specific Gal4s and find that more than half were external regulators, that is, from the local microenvironment or more distal sources. Some genes, for example, versatile (vers), encoding a heterochromatin protein, regulates GSC fates differentially in different cell types and through multiple pathways. We also find that mitosis/cytokinesis proteins are especially important for male GSC maintenance. Our findings provide valuable insights and resources for studying stem cell regulation at the organismal level. PMID:27484291

  16. Stress and stem cells.

    PubMed

    Tower, John

    2012-01-01

    The unique properties and functions of stem cells make them particularly susceptible to stresses and also lead to their regulation by stress. Stem cell division must respond to the demand to replenish cells during normal tissue turnover as well as in response to damage. Oxidative stress, mechanical stress, growth factors, and cytokines signal stem cell division and differentiation. Many of the conserved pathways regulating stem cell self-renewal and differentiation are also stress-response pathways. The long life span and division potential of stem cells create a propensity for transformation (cancer) and specific stress responses such as apoptosis and senescence act as antitumor mechanisms. Quiescence regulated by CDK inhibitors and a hypoxic niche regulated by FOXO transcription factor function to reduce stress for several types of stem cells to facilitate long-term maintenance. Aging is a particularly relevant stress for stem cells, because repeated demands on stem cell function over the life span can have cumulative cell-autonomous effects including epigenetic dysregulation, mutations, and telomere erosion. In addition, aging of the organism impairs function of the stem cell niche and systemic signals, including chronic inflammation and oxidative stress.

  17. Stress and stem cells

    PubMed Central

    Tower, John

    2013-01-01

    The unique properties and functions of stem cells make them particularly susceptible to stresses and also lead to their regulation by stress. Stem cell division must respond to the demand to replenish cells during normal tissue turnover as well as in response to damage. Oxidative stress, mechanical stress, growth factors, and cytokines signal stem cell division and differentiation. Many of the conserved pathways regulating stem cell self-renewal and differentiation are also stress-response pathways. The long life span and division potential of stem cells create a propensity for transformation (cancer) and specific stress responses such as apoptosis and senescence act as antitumor mechanisms. Quiescence regulated by CDK inhibitors and a hypoxic niche regulated by FOXO transcription factor function to reduce stress for several types of stem cells to facilitate long-term maintenance. Aging is a particularly relevant stress for stem cells, because repeated demands on stem cell function over the life span can have cumulative cell-autonomous effects including epigenetic dysregulation, mutations, and telomere erosion. In addition, aging of the organism impairs function of the stem cell niche and systemic signals, including chronic inflammation and oxidative stress. PMID:23799624

  18. [From basic research to the clinic. Regulations for preclinical and clinical studies with stem cells].

    PubMed

    Steinhoff, G; Tiedemann, G; Thalheimer, M; Ho, A D

    2008-09-01

    The discovery of human embryonic stem cells at the end of 1998 had a strong influence on the development of stem cell research and led to controversial discussions. The first therapeutic application of adult blood stem cells began after their discovery in 1963 and was accepted as an authorized therapy in the early 1980s. The way from basic research to therapeutic use needed about 20 years and was also discussed in a controversial way similar to the discussions of today. The regulatory environment at that time, however, allowed a quick translation of the results from basic research to the clinic. Today many new stem cell therapies for a multitude of diseases are under development. Their clinical realization is regulated by the AMG (Arzneimittelgesetz). For nonclinical research as well as for clinical research, specific regulations are enacted to guarantee a structured and safe launch. Time, know how and money for planning, request for authorization and conduction of a clinical trial should not be underestimated. For clinical application of stem cell products authorization by the proper authorities is mandatory.

  19. Adipocyte Metabolic Pathways Regulated by Diet Control the Female Germline Stem Cell Lineage in Drosophila melanogaster.

    PubMed

    Matsuoka, Shinya; Armstrong, Alissa R; Sampson, Leesa L; Laws, Kaitlin M; Drummond-Barbosa, Daniela

    2017-06-01

    Nutrients affect adult stem cells through complex mechanisms involving multiple organs. Adipocytes are highly sensitive to diet and have key metabolic roles, and obesity increases the risk for many cancers. How diet-regulated adipocyte metabolic pathways influence normal stem cell lineages, however, remains unclear. Drosophila melanogaster has highly conserved adipocyte metabolism and a well-characterized female germline stem cell (GSC) lineage response to diet. Here, we conducted an isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis to identify diet-regulated adipocyte metabolic pathways that control the female GSC lineage. On a rich (relative to poor) diet, adipocyte Hexokinase-C and metabolic enzymes involved in pyruvate/acetyl-CoA production are upregulated, promoting a shift of glucose metabolism toward macromolecule biosynthesis. Adipocyte-specific knockdown shows that these enzymes support early GSC progeny survival. Further, enzymes catalyzing fatty acid oxidation and phosphatidylethanolamine synthesis in adipocytes promote GSC maintenance, whereas lipid and iron transport from adipocytes controls vitellogenesis and GSC number, respectively. These results show a functional relationship between specific metabolic pathways in adipocytes and distinct processes in the GSC lineage, suggesting the adipocyte metabolism-stem cell link as an important area of investigation in other stem cell systems. Copyright © 2017 by the Genetics Society of America.

  20. c-Rel Regulates Inscuteable Gene Expression during Mouse Embryonic Stem Cell Differentiation*

    PubMed Central

    Ishibashi, Riki; Kozuki, Satoshi; Kamakura, Sachiko; Sumimoto, Hideki; Toyoshima, Fumiko

    2016-01-01

    Inscuteable (Insc) regulates cell fate decisions in several types of stem cells. Although it is recognized that the expression levels of mouse INSC govern the balance between symmetric and asymmetric stem cell division, regulation of mouse Insc gene expression remains poorly understood. Here, we showed that mouse Insc expression transiently increases at an early stage of differentiation, when mouse embryonic stem (mES) cells differentiate into bipotent mesendoderm capable of producing both endoderm and mesoderm in defined culture conditions. We identified the minimum transcriptional regulatory element (354 bases) that drives mouse Insc transcription in mES cells within a region >5 kb upstream of the mouse Insc transcription start site. We found that the transcription factor reticuloendotheliosis oncogene (c-Rel) bound to the minimum element and promoted mouse Insc expression in mES cells. In addition, short interfering RNA-mediated knockdown of either mouse INSC or c-Rel protein decreased mesodermal cell populations without affecting differentiation into the mesendoderm or endoderm. Furthermore, overexpression of mouse INSC rescued the mesoderm-reduced phenotype induced by knockdown of c-Rel. We propose that regulation of mouse Insc expression by c-Rel modulates cell fate decisions during mES cell differentiation. PMID:26694615

  1. c-Rel Regulates Inscuteable Gene Expression during Mouse Embryonic Stem Cell Differentiation.

    PubMed

    Ishibashi, Riki; Kozuki, Satoshi; Kamakura, Sachiko; Sumimoto, Hideki; Toyoshima, Fumiko

    2016-02-12

    Inscuteable (Insc) regulates cell fate decisions in several types of stem cells. Although it is recognized that the expression levels of mouse INSC govern the balance between symmetric and asymmetric stem cell division, regulation of mouse Insc gene expression remains poorly understood. Here, we showed that mouse Insc expression transiently increases at an early stage of differentiation, when mouse embryonic stem (mES) cells differentiate into bipotent mesendoderm capable of producing both endoderm and mesoderm in defined culture conditions. We identified the minimum transcriptional regulatory element (354 bases) that drives mouse Insc transcription in mES cells within a region >5 kb upstream of the mouse Insc transcription start site. We found that the transcription factor reticuloendotheliosis oncogene (c-Rel) bound to the minimum element and promoted mouse Insc expression in mES cells. In addition, short interfering RNA-mediated knockdown of either mouse INSC or c-Rel protein decreased mesodermal cell populations without affecting differentiation into the mesendoderm or endoderm. Furthermore, overexpression of mouse INSC rescued the mesoderm-reduced phenotype induced by knockdown of c-Rel. We propose that regulation of mouse Insc expression by c-Rel modulates cell fate decisions during mES cell differentiation.

  2. Jawbone microenvironment promotes periodontium regeneration by regulating the function of periodontal ligament stem cells

    PubMed Central

    Zhu, Bin; Liu, Wenjia; Liu, Yihan; Zhao, Xicong; Zhang, Hao; Luo, Zhuojing; Jin, Yan

    2017-01-01

    During tooth development, the jawbone interacts with dental germ and provides the development microenvironment. Jawbone-derived mesenchymal stem cells (JBMSCs) maintain this microenvironment for root and periodontium development. However, the effect of the jawbone microenvironment on periodontium tissue regeneration is largely elusive. Our previous study showed that cell aggregates (CAs) of bone marrow mesenchymal stem cells promoted periodontium regeneration on the treated dentin scaffold. Here, we found that JBMSCs enhanced not only the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) but also their adhesion to titanium (Ti) material surface. Importantly, the compound CAs of PDLSCs and JBMSCs regenerated periodontal ligament-like fibers and mineralized matrix on the Ti scaffold surface, both in nude mice ectopic and minipig orthotopic transplantations. Our data revealed that an effective regenerative microenvironment, reconstructed by JBMSCs, promoted periodontium regeneration by regulating PDLSCs function on the Ti material. PMID:28053317

  3. Epigenetic Regulation of miRNAs and Breast Cancer Stem Cells

    PubMed Central

    Duru, Nadire; Gernapudi, Ramkishore; Eades, Gabriel; Eckert, Richard; Zhou, Qun

    2015-01-01

    MicroRNAs have emerged as important targets of chemopreventive strategies in breast cancer. We have found that miRNAs are dysregulated at an early stage in breast cancer, in non-malignant Ductal Carcinoma In Situ. Many dietary chemoprevention agents can act by epigenetically activating miRNA-signaling pathways involved in tumor cell proliferation and invasive progression. In addition, many miRNAs activated via chemopreventive strategies target cancer stem cell signaling and prevent tumor progression or relapse. Specifically, we have found that miRNAs regulate DCIS stem cells, which may play important roles in breast cancer progression to invasive disease. We have shown that chemopreventive agents can directly inhibit DCIS stem cells and block tumor formation in vivo, via activation of tumor suppressor miRNAs. PMID:26052481

  4. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    PubMed Central

    Landowski, Lila M.; Young, Kaylene M.

    2016-01-01

    The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions. PMID:26949399

  5. The metabolome regulates the epigenetic landscape during naive-to-primed human embryonic stem cell transition.

    PubMed

    Sperber, Henrik; Mathieu, Julie; Wang, Yuliang; Ferreccio, Amy; Hesson, Jennifer; Xu, Zhuojin; Fischer, Karin A; Devi, Arikketh; Detraux, Damien; Gu, Haiwei; Battle, Stephanie L; Showalter, Megan; Valensisi, Cristina; Bielas, Jason H; Ericson, Nolan G; Margaretha, Lilyana; Robitaille, Aaron M; Margineantu, Daciana; Fiehn, Oliver; Hockenbery, David; Blau, C Anthony; Raftery, Daniel; Margolin, Adam A; Hawkins, R David; Moon, Randall T; Ware, Carol B; Ruohola-Baker, Hannele

    2015-12-01

    For nearly a century developmental biologists have recognized that cells from embryos can differ in their potential to differentiate into distinct cell types. Recently, it has been recognized that embryonic stem cells derived from both mice and humans exhibit two stable yet epigenetically distinct states of pluripotency: naive and primed. We now show that nicotinamide N-methyltransferase (NNMT) and the metabolic state regulate pluripotency in human embryonic stem cells (hESCs).  Specifically, in naive hESCs, NNMT and its enzymatic product 1-methylnicotinamide are highly upregulated, and NNMT is required for low S-adenosyl methionine (SAM) levels and the H3K27me3 repressive state. NNMT consumes SAM in naive cells, making it unavailable for histone methylation that represses Wnt and activates the HIF pathway in primed hESCs. These data support the hypothesis that the metabolome regulates the epigenetic landscape of the earliest steps in human development.

  6. Signal integration by Ca(2+) regulates intestinal stem-cell activity.

    PubMed

    Deng, Hansong; Gerencser, Akos A; Jasper, Heinrich

    2015-12-10

    Somatic stem cells maintain tissue homeostasis by dynamically adjusting proliferation and differentiation in response to stress and metabolic cues. Here we identify Ca(2+) signalling as a central regulator of intestinal stem cell (ISC) activity in Drosophila. We show that dietary L-glutamate stimulates ISC division and gut growth. The metabotropic glutamate receptor (mGluR) is required in ISCs for this response, and for an associated modulation of cytosolic Ca(2+) oscillations that results in sustained high cytosolic Ca(2+) concentrations. High cytosolic Ca(2+) concentrations induce ISC proliferation by regulating Calcineurin and CREB-regulated transcriptional co-activator (Crtc). In response to a wide range of dietary and stress stimuli, ISCs reversibly transition between Ca(2+) oscillation states that represent poised or activated modes of proliferation, respectively. We propose that the dynamic regulation of intracellular Ca(2+) levels allows effective integration of diverse mitogenic signals in ISCs to adapt their proliferative activity to the needs of the tissue.

  7. Redox regulation by Keap1 and Nrf2 controls intestinal stem cell proliferation in Drosophila

    PubMed Central

    Hochmuth, Christine E.; Biteau, Benoit; Bohmann, Dirk; Jasper, Heinrich

    2010-01-01

    In Drosophila, intestinal stem cells (ISCs) respond to oxidative challenges and inflammation by increasing proliferation rates. This phenotype is part of a regenerative response, but can lead to hyperproliferation and epithelial degeneration in the aging animal. Here we show that Nrf2, a master regulator of the cellular redox state, specifically controls the proliferative activity of ISCs, promoting intestinal homeostasis. We find that Nrf2 is constitutively active in ISCs, and that repression of Nrf2 by its negative regulator Keap1 is required for ISC proliferation. We further show that Nrf2 and Keap1 exert this function in ISCs by regulating the intracellular redox balance. Accordingly, loss of Nrf2 in ISCs causes accumulation of reactive oxygen species and accelerates age-related degeneration of the intestinal epithelium. Our findings establish Keap1 and Nrf2 as a critical redox management system that regulates stem cell function in high-turnover tissues. PMID:21295275

  8. Wnt signaling regulates the stemness of lung cancer stem cells and its inhibitors exert anticancer effect on lung cancer SPC-A1 cells.

    PubMed

    Zhang, Xueyan; Lou, Yuqing; Wang, Huimin; Zheng, Xiaoxuan; Dong, Qianggang; Sun, Jiayuan; Han, Baohui

    2015-04-01

    Wnt signaling plays an important role in regulating the activity of cancer stem cells (CSCs) in a variety of cancers. In this study, we explored the role of Wnt signaling in the lung cancer stem cells (LCSCs). LCSCs were obtained by sphere culture, for which human lung adenocarcinoma cell line SPC-A1 was treated with IGF, EGF and FGF-10. The stemness of LCSCs was confirmed by immunofluorescence, and pathway analysis was performed by functional genome screening and RT-PCR. The relationship between the identified signaling pathway and the expression of the stemness genes was explored by agonist/antagonist assay. Moreover, the effects of different signaling molecule inhibitors on sphere formation, cell viability and colony formation were also analyzed. The results showed that LCSCs were successfully generated as they expressed pluripotent stem cell markers Nanog and Oct 4, and lung distal epithelial markers CCSP and SP-C, by which the phenotype characterization of stem cells can be confirmed. The involvement of Wnt pathway in LCSCs was identified by functional genome screening and verified by RT-PCR. The expression of Wnt signaling components was closely related to the expression of the Nanog and Oct 4. Furthermore, targeting Wnt signaling pathway by using different signaling molecule inhibitors can exert anticancer effects. In conclusion, Wnt signaling pathway is involved in the stemness regulation of LCSCs and might be considered as a potential therapeutic target in lung adenocarcinoma.

  9. The Endocrine Regulation of Stem Cells: Physiological Importance and Pharmacological Potentials for Cell-Based Therapy.

    PubMed

    Ghorbani, Ahmad; Naderi-Meshkin, Hojjat

    2016-01-01

    Throughout life, different types of stem cells participate in tissue generation, maintenance, plasticity, and repair. Their abilities to secrete growth factors, to proliferate and differentiate into several cell lineages, and to migrate and home into the damaged tissues have made them attractive candidates for cell therapy and tissue engineering applications. Normal stem cell function is tied to the cell-intrinsic mechanisms and extrinsic signals derived from the surrounding microenvironment or circulation. Understanding the regulatory signals that govern stem cell functions is essential in order to have full knowledge about organogenesis, tissue maintenance and tissue plasticity in the physiological condition. It is also important for optimizing tissue engineering and improving the therapeutic efficiency of stem cells in regenerative medicine. A growing body of evidence indicates that hormonal signals can critically influence stem cell functions in fetal, postnatal, and adult tissues. This review focuses on recent studies revealing how growth hormone, insulin, thyroid hormone, parathormone, adrenocorticotropin, glucocorticoids, erythropoietin, and gastrointestinal hormones control stem cell behavior through influencing survival, proliferation, migration, homing, and differentiation of these cells. Moreover, how environmental factors such as exercise, hypoxia, and nutrition might affect stem cell functions through influencing the endocrine system is discussed. Some of the current limitations of cell therapy and how hormones can help overcoming these limitations are briefly outlined.

  10. An RbAp48-like gene regulates adult stem cells in planarians.

    PubMed

    Bonuccelli, Lucia; Rossi, Leonardo; Lena, Annalisa; Scarcelli, Vittoria; Rainaldi, Giuseppe; Evangelista, Monica; Iacopetti, Paola; Gremigni, Vittorio; Salvetti, Alessandra

    2010-03-01

    Retinoblastoma-associated proteins 46 and 48 (RbAp46 and RbAp48) are factors that are components of different chromatin-modelling complexes, such as polycomb repressive complex 2, the activity of which is related to epigenetic gene regulation in stem cells. To date, no direct findings are available on the in vivo role of RbAp48 in stem-cell biology. We recently identified DjRbAp48 - a planarian (Dugesia japonica) homologue of human RBAP48 - expression of which is restricted to the neoblasts, the adult stem cells of planarians. In vivo silencing of DjRbAp48 induces lethality and inability to regenerate, even though neoblasts proliferate and accumulate after wounding. Despite a partial reduction in neoblast number, we were always able to detect a significant number of these cells in DjRbAp48 RNAi animals. Parallel to the decrease in neoblasts, a reduction in the number of differentiated cells and the presence of apoptotic-like neoblasts were detectable in RNAi animals. These findings suggest that DjRbAp48 is not involved in neoblast maintenance, but rather in the regulation of differentiation of stem-cell progeny. We discuss our data, taking into account the possibility that DjRbAp48 might control the expression of genes necessary for cell differentiation by influencing chromatin architecture.

  11. Planarian PTEN homologs regulate stem cells and regeneration through TOR signaling.

    PubMed

    Oviedo, Néstor J; Pearson, Bret J; Levin, Michael; Sánchez Alvarado, Alejandro

    2008-01-01

    We have identified two genes, Smed-PTEN-1 and Smed-PTEN-2, capable of regulating stem cell function in the planarian Schmidtea mediterranea. Both genes encode proteins homologous to the mammalian tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Inactivation of Smed-PTEN-1 and -2 by RNA interference (RNAi) in planarians disrupts regeneration, and leads to abnormal outgrowths in both cut and uncut animals followed soon after by death (lysis). The resulting phenotype is characterized by hyperproliferation of neoblasts (planarian stem cells), tissue disorganization and a significant accumulation of postmitotic cells with impaired differentiation capacity. Further analyses revealed that rapamycin selectively prevented such accumulation without affecting the normal neoblast proliferation associated with physiological turnover and regeneration. In animals in which PTEN function is abrogated, we also detected a significant increase in the number of cells expressing the planarian Akt gene homolog (Smed-Akt). However, functional abrogation of Smed-Akt in Smed-PTEN RNAi-treated animals does not prevent cell overproliferation and lethality, indicating that functional abrogation of Smed-PTEN is sufficient to induce abnormal outgrowths. Altogether, our data reveal roles for PTEN in the regulation of planarian stem cells that are strikingly conserved to mammalian models. In addition, our results implicate this protein in the control of stem cell maintenance during the regeneration of complex structures in planarians.

  12. Alternative promoters regulate transcription of the gene that encodes stem cell surface protein AC133.

    PubMed

    Shmelkov, Sergey V; Jun, Lin; St Clair, Ryan; McGarrigle, Deirdre; Derderian, Christopher A; Usenko, Jaroslav K; Costa, Carla; Zhang, Fan; Guo, Xinzheng; Rafii, Shahin

    2004-03-15

    AC133 is a member of a novel family of cell surface proteins with 5 transmembrane domains. The function of AC133 is unknown. Although AC133 mRNA is detected in different tissues, its expression in the hematopoietic system is restricted to CD34+ stem cells. AC133 is also expressed on stem cells of other tissues, including endothelial progenitor cells. However, despite the potential importance of AC133 to the field of stem cell biology, nothing is known about the transcriptional regulation of AC133 expression. In this report we showed that the human AC133 gene has at least 9 distinctive 5'-untranslated region (UTR) exons, resulting in the formation of at least 7 alternatively spliced 5'-UTR isoforms of AC133 mRNA, which are expressed in a tissue-dependent manner. We found that transcription of these AC133 isoforms is controlled by 5 alternative promoters, and we demonstrated their activity on AC133-expressing cell lines using a luciferase reporter system. We also showed that in vitro methylation of 2 of these AC133 promoters completely suppresses their activity, suggesting that methylation plays a role in their regulation. Identification of tissue-specific AC133 promoters may provide a novel method to isolate tissue-specific stem and progenitor cells.

  13. MicroRNA Regulation of CD44+ Prostate Tumor Stem/Progenitor Cells and Prostate Cancer Development/Metastasis

    DTIC Science & Technology

    2013-05-01

    Diehn M, Liu H, Panula SP, Chiao E, Dirbas FM, Somlo G, Pera RA, Lao K, Clarke MF. Downregulation of miRNA- 200c links breast cancer stem cells with...renewal in mouse embryonic stem cells. Nature 463, 621–626 (2010). 4. Yu, F. et al. let-7 regulates self-renewal and tumorigenicity of breast cancer ...cells. Cell 131, 1109–1123 (2007). 5. Shimono, Y. et al. Downregulation of miRNA-200c links breast cancer stem cells with normal stem cells. Cell 138

  14. MicroRNA Regulation and Role in Stem Cell Maintenance, Cardiac Differentiation and Hypertrophy

    PubMed Central

    Kuppusamy, K.T.; Sperber, H.; Ruohola-Baker, H.

    2014-01-01

    There are currently 1527 known microRNAs (miRNAs) in human, each of which may regulate hundreds or thousands of target genes. miRNA expression levels vary between cell types; for example, miR-302 and miR-290 families are highly enriched in embryonic stem cells, while miR-1 is a muscle specific miRNA. miRNA biosynthesis and function are highly regulated and this regulation may be cell type specific. The processing enzymes and factors that recognize features in sequence and secondary structure of the miRNA play key roles in regulating the production of mature miRNA. Mature miRNA enriched in stem cells control stem cell self-renewal as well as their differentiation. Though specific miRNAs have been shown to control differentiation towards various lineages such as neural or skin cells, some of the most well characterized miRNAs have been found in promoting the formation of cardiac cells. In addition, miRNAs also play a critical role in cardiomyocyte hypertrophy, especially in a pathological context. Such miRNAs are predicted to be therapeutic targets for treating cardiovascular diseases. In this review we will discuss how miRNAs act to maintain the stem cell state and also explore the current knowledge of the mechanisms that regulate miRNAs. Furthermore, we will discuss the emerging roles of miRNAs using cardiomyocyte differentiation and maturation as a paradigm. Emphasis will also be given on some of the less ventured areas such as the role of miRNAs in the physiological maturation of cardiomyocytes. These potentially beneficial miRNAs are likely to improve cardiac function in both in vivo and in vitro settings and thus provide additional strategy to treat heart diseases and more importantly serve as a good model for understanding cardiomyocyte maturation in vitro. PMID:23642057

  15. Novel function of MDA-9/Syntenin (SDCBP) as a regulator of survival and stemness in glioma stem cells

    PubMed Central

    Talukdar, Sarmistha; Das, Swadesh K.; Pradhan, Anjan K.; Emdad, Luni; Shen, Xue-Ning; Windle, Jolene J.; Sarkar, Devanand; Fisher, Paul B.

    2016-01-01

    Glioblastoma multiforme (GBM) is an aggressive cancer with current therapies only marginally impacting on patient survival. Glioma stem cells (GSCs), a subpopulation of highly tumorigenic cells, are considered major contributors to glioma progression and play seminal roles in therapy resistance, immune evasion and increased invasion. Despite clinical relevance, effective/selective therapeutic targeting strategies for GSCs do not exist, potentially due to the lack of a definitive understanding of key regulators of GSCs. Consequently, there is a pressing need to identify therapeutic targets and novel options to effectively target this therapy-resistant cell population. The precise roles of GSCs in governing GBM development, progression and prognosis are under intense scrutiny, but key upstream regulatory genes remain speculative. MDA-9/Syntenin (SDCBP), a scaffold protein, regulates tumor pathogenesis in multiple cancers. Highly aggressive cancers like GBM express elevated levels of MDA-9 and contain increased populations of GSCs. We now uncover a unique function of MDA-9 as a facilitator and determinant of glioma stemness and survival. Mechanistically, MDA-9 regulates multiple stemness genes (Nanog, Oct4 and Sox2) through activation of STAT3. MDA-9 controls survival of GSCs by activating the NOTCH1 pathway through phospho-Src and DLL1. Once activated, cleaved NOTCH1 regulates C-Myc expression through RBPJK, thereby facilitating GSC growth and proliferation. Knockdown of MDA-9 affects the NOTCH1/C-Myc and p-STAT3/Nanog pathways causing a loss of stemness and initiation of apoptosis in GSCs. Our data uncover a previously unidentified relationship between MDA-9 and GSCs, reinforcing relevance of this gene as a potential therapeutic target in GBM. PMID:27472461

  16. AMPKα1-LDH pathway regulates muscle stem cell self-renewal by controlling metabolic homeostasis.

    PubMed

    Theret, Marine; Gsaier, Linda; Schaffer, Bethany; Juban, Gaëtan; Ben Larbi, Sabrina; Weiss-Gayet, Michèle; Bultot, Laurent; Collodet, Caterina; Foretz, Marc; Desplanches, Dominique; Sanz, Pascual; Zang, Zizhao; Yang, Lin; Vial, Guillaume; Viollet, Benoit; Sakamoto, Kei; Brunet, Anne; Chazaud, Bénédicte; Mounier, Rémi

    2017-07-03

    Control of stem cell fate to either enter terminal differentiation versus returning to quiescence (self-renewal) is crucial for tissue repair. Here, we showed that AMP-activated protein kinase (AMPK), the master metabolic regulator of the cell, controls muscle stem cell (MuSC) self-renewal. AMPKα1(-/-) MuSCs displayed a high self-renewal rate, which impairs muscle regeneration. AMPKα1(-/-) MuSCs showed a Warburg-like switch of their metabolism to higher glycolysis. We identified lactate dehydrogenase (LDH) as a new functional target of AMPKα1. LDH, which is a non-limiting enzyme of glycolysis in differentiated cells, was tightly regulated in stem cells. In functional experiments, LDH overexpression phenocopied AMPKα1(-/-) phenotype, that is shifted MuSC metabolism toward glycolysis triggering their return to quiescence, while inhibition of LDH activity rescued AMPKα1(-/-) MuSC self-renewal. Finally, providing specific nutrients (galactose/glucose) to MuSCs directly controlled their fate through the AMPKα1/LDH pathway, emphasizing the importance of metabolism in stem cell fate. © 2017 The Authors.

  17. Genetic interaction of PGE2 and Wnt signaling regulates developmental specification of stem cells and regeneration

    PubMed Central

    Goessling, Wolfram; North, Trista E.; Loewer, Sabine; Lord, Allegra M.; Lee, Sang; Stoick-Cooper, Cristi L.; Weidinger, Gilbert; Puder, Mark; Daley, George Q.; Moon, Randall T.; Zon, Leonard I.

    2009-01-01

    Summary Interactions between developmental signaling pathways govern the formation and function of stem cells. Prostaglandin (PG) E2 regulates vertebrate hematopoietic stem cells (HSC). Similarly, the Wnt signaling pathway controls HSC self-renewal and bone marrow repopulation. Here, we show that wnt reporter activity in zebrafish HSCs is responsive to PGE2 modulation, demonstrating a direct interaction in vivo. Inhibition of PGE2 synthesis blocked wnt-induced alterations in HSC formation. PGE2 modified the wnt signaling cascade at the level of β-catenin degradation through cAMP/PKA-mediated stabilizing phosphorylation events. The PGE2/Wnt interaction regulated murine stem and progenitor populations in vitro in hematopoietic ES cell assays and in vivo following transplantation. The relationship between PGE2 and Wnt was also conserved during regeneration of other organ systems. Our work provides the first in vivo evidence that Wnt activation in stem cells requires PGE2, and suggests the PGE2/Wnt interaction is a master regulator of vertebrate regeneration and recovery. PMID:19303855

  18. Ceramide synthase 4 regulates stem cell homeostasis and hair follicle cycling.

    PubMed

    Peters, Franziska; Vorhagen, Susanne; Brodesser, Susanne; Jakobshagen, Kristin; Brüning, Jens C; Niessen, Carien M; Krönke, Martin

    2015-06-01

    Ceramides are crucial for skin barrier function, but little is known about the regulation of epidermal appendages and whether stem cell populations that control their regeneration depend on specific ceramide species. Here we demonstrate that ceramide synthase 4 (CerS4) is highly expressed in the epidermis of adult mice where it is localized in the interfollicular epidermis and defined populations within the pilosebaceous unit. Inactivation of CerS4 in mice resulted in precocious activation of hair follicle bulge stem cells while expanding the Lrig1(+) junctional zone and sebaceous glands. This was preceded first by a decrease in bone morphogenetic protein (BMP) and a subsequent increase in Wnt signaling. This imbalance in quiescent versus activating signals likely promoted a prolonged anagen-like hair follicle state after the second catagen, which exhausted stem cells over time ultimately resulting in hair loss in aged mice. K14-Cre-mediated deletion of CerS4 revealed a similar phenotype, thus suggesting an epidermis intrinsic function of CerS4 in regulating the regeneration of the pilosebaceous unit. The data indicate that CerS4-directed epidermal ceramide composition is essential to control hair follicle stem and progenitor cell behavior potentially through its regulation of BMP and Wnt signaling.

  19. Abscission is regulated by the ESCRT-III protein shrub in Drosophila germline stem cells.

    PubMed

    Matias, Neuza Reis; Mathieu, Juliette; Huynh, Jean-René

    2015-02-01

    Abscission is the final event of cytokinesis that leads to the physical separation of the two daughter cells. Recent technical advances have allowed a better understanding of the cellular and molecular events leading to abscission in isolated yeast or mammalian cells. However, how abscission is regulated in different cell types or in a developing organism remains poorly understood. Here, we characterized the function of the ESCRT-III protein Shrub during cytokinesis in germ cells undergoing a series of complete and incomplete divisions. We found that Shrub is required for complete abscission, and that levels of Shrub are critical for proper timing of abscission. Loss or gain of Shrub delays abscission in germline stem cells (GSCs), and leads to the formation of stem-cysts, where daughter cells share the same cytoplasm as the mother stem cell and cannot differentiate. In addition, our results indicate a negative regulation of Shrub by the Aurora B kinase during GSC abscission. Finally, we found that Lethal giant discs (lgd), known to be required for Shrub function in the endosomal pathway, also regulates the duration of abscission in GSCs.

  20. Wnt signaling-mediated redox regulation maintains the germ line stem cell differentiation niche.

    PubMed

    Wang, Su; Gao, Yuan; Song, Xiaoqing; Ma, Xing; Zhu, Xiujuan; Mao, Ying; Yang, Zhihao; Ni, Jianquan; Li, Hua; Malanowski, Kathryn E; Anoja, Perera; Park, Jungeun; Haug, Jeff; Xie, Ting

    2015-10-09

    Adult stem cells continuously undergo self-renewal and generate differentiated cells. In the Drosophila ovary, two separate niches control germ line stem cell (GSC) self-renewal and differentiation processes. Compared to the self-renewing niche, relatively little is known about the maintenance and function of the differentiation niche. In this study, we show that the cellular redox state regulated by Wnt signaling is critical for the maintenance and function of the differentiation niche to promote GSC progeny differentiation. Defective Wnt signaling causes the loss of the differentiation niche and the upregulated BMP signaling in differentiated GSC progeny, thereby disrupting germ cell differentiation. Mechanistically, Wnt signaling controls the expression of multiple glutathione-S-transferase family genes and the cellular redox state. Finally, Wnt2 and Wnt4 function redundantly to maintain active Wnt signaling in the differentiation niche. Therefore, this study has revealed a novel strategy for Wnt signaling in regulating the cellular redox state and maintaining the differentiation niche.

  1. Navigating the quagmire: the regulation of human embryonic stem cell research.

    PubMed

    Jones, D G; Towns, C R

    2006-05-01

    Embryonic stem (ES) cell research has garnered almost unprecedented attention. Debate over the boundaries of such research is ongoing, and the regulation of the field varies widely between countries. This article identifies and evaluates the four major positions that emanate from current international regulations. ES cell policies may ultimately impact on public health, and hence they must be both rigorous and transparent. We contend that these goals will only be achieved if policy is both ethically consistent and clinically realistic with regard to the ability to achieve therapeutic goals. We conclude that policies allowing the ongoing extraction of stem cells from spare in vitro fertilization embryos and the creation of embryos for research (within set limitations) cope most adequately with the tension between varying views on the moral status of the human embryo and the therapeutic potential inherent within ES cell research.

  2. Kindlin-1 controls Wnt and TGF-β availability to regulate cutaneous epithelial stem cell proliferation

    PubMed Central

    Rognoni, Emanuel; Widmaier, Moritz; Jakobson, Madis; Ruppert, Raphael; Ussar, Siegfried; Katsougkri, Despoina; Böttcher, Ralph T.; Lai-Cheong, Joey E.; Rifkin, Daniel B.; McGrath, John A.; Fässler, Reinhard

    2014-01-01

    Kindlin-1 is an integrin tail binding protein that controls integrin activation. Mutations in the FERMT-1 gene lead to Kindler Syndrome in man, which is characterized by skin blistering, premature skin ageing and skin cancer of unknown etiology. Here we show that loss of Kindlin-1 in mouse keratinocytes recapitulates Kindler Syndrome, and in addition produces enlarged and hyperactive stem cell compartments, which lead to hyperthickened epidermis, ectopic hair follicle development and increased skin tumor susceptibility. Mechanistically, Kindlin-1 controls keratinocyte adhesion through β1-class integrins and proliferation and differentiation of cutaneous epithelial stem cells by promoting αvβ6 integrin-mediated TGFβ activation and by inhibiting Wnt-β-catenin signaling through an integrin-independent regulation of Wnt ligand expression. Our findings assign Kindlin-1 the novel and essential task to control cutaneous epithelial stem cell homeostasis by balancing TGFβ mediated growth inhibitory and Wnt-β-catenin mediated growth-promoting signals. PMID:24681597

  3. The ubiquitin ligase HUWE1 regulates hematopoietic stem cell maintenance and lymphoid commitment

    PubMed Central

    King, Bryan; Boccalatte, Francesco; Moran-Crusio, Kelly; Wolf, Elmar; Wang, Jingjing; Kayembe, Clarisse; Lazaris, Charalampos; Yu, Xiaofeng; Aranda-Orgilles, Beatriz; Lasorella, Anna; Aifantis, Iannis

    2016-01-01

    Hematopoietic stem cells (HSCs) are dormant in the bone marrow and can be activated in response to diverse stresses to replenish all blood cell types. Here we identify the ubiquitin ligase Huwe1 as a crucial regulator of HSC functions via its post-translational control of N-myc. We found Huwe1 to be essential for HSC self-renewal, quiescence and lymphoid fate specification. Using a novel fluorescent fusion allele (MycnM), we observed that N-myc expression was restricted to the most immature, multipotent stem and progenitor populations. N-myc was upregulated in response to stress or upon loss of Huwe1, leading to increased proliferation and stem cell exhaustion. Mycn depletion reversed most of these phenotypes in vivo, suggesting that the attenuation of N-myc by Huwe1 is essential to reestablish homeostasis following stress. PMID:27668798

  4. Concise Review: Geminin-A Tale of Two Tails: DNA Replication and Transcriptional/Epigenetic Regulation in Stem Cells.

    PubMed

    Patmanidi, Alexandra L; Champeris Tsaniras, Spyridon; Karamitros, Dimitris; Kyrousi, Christina; Lygerou, Zoi; Taraviras, Stavros

    2017-02-01

    Molecular mechanisms governing maintenance, commitment, and differentiation of stem cells are largely unexploited. Molecules involved in the regulation of multiple cellular processes are of particular importance for stem cell physiology, as they integrate different signals and coordinate cellular decisions related with self-renewal and fate determination. Geminin has emerged as a critical factor in DNA replication and stem cell differentiation in different stem cell populations. Its inhibitory interaction with Cdt1, a member of the prereplicative complex, ensures the controlled timing of DNA replication and, consequently, genomic stability in actively proliferating cells. In embryonic as well as somatic stem cells, Geminin has been shown to interact with transcription factors and epigenetic regulators to drive gene expression programs and ultimately guide cell fate decisions. An ever-growing number of studies suggests that these interactions of Geminin and proteins regulating transcription are conserved among metazoans. Interactions between Geminin and proteins modifying the epigenome, such as members of the repressive Polycomb group and the SWI/SNF proteins of the permissive Trithorax, have long been established. The complexity of these interactions, however, is only just beginning to unravel, revealing key roles on maintaining stem cell self-renewal and fate specification. In this review, we summarize current knowledge and give new perspectives for the role of Geminin on transcriptional and epigenetic regulation, alongside with its regulatory activity in DNA replication and their implication in the regulation of stem and progenitor cell biology. Stem Cells 2017;35:299-310. © 2016 AlphaMed Press.

  5. Regulation of c-Myc Expression by Ahnak Promotes Induced Pluripotent Stem Cell Generation*

    PubMed Central

    Lim, Hee Jung; Kim, Jusong; Park, Chang-Hwan; Lee, Sang A.; Lee, Man Ryul; Kim, Kye-Seong; Kim, Jaesang; Bae, Yun Soo

    2016-01-01

    We have previously reported that Ahnak-mediated TGFβ signaling leads to down-regulation of c-Myc expression. Here, we show that inhibition of Ahnak can promote generation of induced pluripotent stem cells (iPSC) via up-regulation of endogenous c-Myc. Consistent with the c-Myc inhibitory role of Ahnak, mouse embryonic fibroblasts from Ahnak-deficient mouse (Ahnak−/− MEF) show an increased level of c-Myc expression compared with wild type MEF. Generation of iPSC with just three of the four Yamanaka factors, Oct4, Sox2, and Klf4 (hereafter 3F), was significantly enhanced in Ahnak−/− MEF. Similar results were obtained when Ahnak-specific shRNA was applied to wild type MEF. Of note, expressionof Ahnak was significantly induced during the formation of embryoid bodies from embryonic stem cells, suggesting that Ahnak-mediated c-Myc inhibition is involved in embryoid body formation and the initial differentiation of pluripotent stem cells. The iPSC from 3F-infected Ahnak−/− MEF cells (Ahnak−/−-iPSC-3F) showed expression of all stem cell markers examined and the capability to form three primary germ layers. Moreover, injection of Ahnak−/−-iPSC-3F into athymic nude mice led to development of teratoma containing tissues from all three primary germ layers, indicating that iPSC from Ahnak−/− MEF are bona fide pluripotent stem cells. Taken together, these data provide evidence for a new role for Ahnak in cell fate determination during development and suggest that manipulation of Ahnak and the associated signaling pathway may provide a means to regulate iPSC generation. PMID:26598518

  6. Nicastrin regulates breast cancer stem cell properties and tumor growth in vitro and in vivo.

    PubMed

    Lombardo, Ylenia; Filipović, Aleksandra; Molyneux, Gemma; Periyasamy, Manikandan; Giamas, Georgios; Hu, Yunhui; Trivedi, Pritesh S; Wang, Jayson; Yagüe, Ernesto; Michel, Loren; Coombes, R Charles

    2012-10-09

    Nicastrin (NCT) is a crucial component of the γ-secretase (GS) enzyme, which prompted investigations into its biological role in cancer. We have previously shown that nicastrin is overexpressed in breast cancer (BC), conferring worse overall survival in invasive, ERα negative patients. Here, we used 2D and 3D Matrigel, anchorage-independent growth conditions and a breast cancer xenograft mouse model to assess the impact of nicastrin on breast cancer stem cell (BCSC) propagation and invasion in vitro and tumor growth in vivo. Stable knockdown of nicastrin in HCC1806 breast cancer cells reduced cell invasion by 51.4 ± 1.7%, accompanied by a morphological change to a rounded cell phenotype and down-regulation of vimentin, Snail, Twist, MMP2, and MMP9. We observed a reduction of the pool of CD44(+)/CD24(-) and ALDH1 high breast cancer stem cells by threefold and twofold, respectively, and a reduction by 2.6-fold of the mammospheres formation. Nicastrin overexpression in nontransformed MCF10A cells caused an induction of epithelial to mesenchymal regulators, as well as a fivefold increased ALDH1 activity, a threefold enrichment for CD44(+)/CD24(-) stem cells, and a 3.2-fold enhanced mammosphere-forming capacity. Using the γ-sescretase inhibiton, Notch1/4 siRNA, and Akt inhibition, we show that nicastrin regulates breast cancer stem cells partly through Notch1 and the Akt pathway. Exploiting serial dilution transplantation of the HCC1806 cells expressing nicastrin and HCC1806 stably depleted of nicastrin, in vivo, we demonstrate that nicastrin inhibition may be relevant for the reduced tumorigenicity of breast cancer cells. These data could serve as a benchmark for development of nicastrin-targeted therapies in breast cancer.

  7. The Three-Layer Concentric Model of Glioblastoma: Cancer Stem Cells, Microenvironmental Regulation, and Therapeutic Implications

    PubMed Central

    Persano, Luca; Rampazzo, Elena; Della Puppa, Alessandro; Pistollato, Francesca; Basso, Giuseppe

    2011-01-01

    Tumors arising in the central nervous system are thought to originate from a sub-population of cells named cancer stem cells (CSCs) or tumor initiating cells (TICs) that possess an immature phenotype, combined with self-renewal and chemotherapy resistance capacity. Moreover, in the last years, these cells have been identified in particular brain tumor niches fundamental for supporting their characteristics. In this paper, we report studies from many authors demonstrating that hypoxia or the so called “hypoxic niche” plays a crucial role in controlling CSC molecular and phenotypic profile. We recently investigated the relationship existing between Glioblastoma (GBM) stem cells and their niche, defining the theory of three-concentric layers model for GBM mass. According to this model, GBM stem cells reside preferentially within the hypoxic core of the tumour mass, while more differentiated cells are mainly localized along the peripheral and vascularized part of the tumour. This GBM model provides explanation of the effects mediated by the tumour microenvironment on the phenotypic and molecular regulation of GBM stem cells, describing their spatial distribution in the tumor bulk. Moreover, we discuss the possible clinical implications of the creation of this model for future GBM patient management and novel therapeutic strategies development. PMID:22125441

  8. Autocrine glutamatergic transmission for the regulation of embryonal carcinoma stem cells

    PubMed Central

    Sun, Fan; An, Shi-Min; Tang, Ya-Bin; Meng, Shuang; Wang, Cong-Hui; Shen, Ying; Chen, Hong-Zhuan; Zhu, Liang

    2016-01-01

    Glutamate behaves as the principal excitatory neurotransmitter in the vertebrate central nervous system and recently demonstrates intercellular signaling activities in periphery cancer cells. How the glutamatergic transmission is organized and operated in cancer stem cells remains undefined. We have identified a glutamatergic transmission circuit in embryonal carcinoma stem cells. The circuit is organized and operated in an autocrine mechanism and suppresses the cell proliferation and motility. Biological analyses determined a repertoire of glutamatergic transmission components, glutaminase, vesicular glutamate transporter, glutamate NMDA receptor, and cell membrane excitatory amino-acid transporter, for glutamate biosynthesis, package for secretion, reaction, and reuptake in mouse and human embryonal carcinoma stem cells. The glutamatergic components were also identified in mouse transplanted teratocarcinoma and in human primary teratocarcinoma tissues. Released glutamate acting as the signal was directly quantified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Genetic and pharmacological abolishment of the endogenously released glutamate-induced tonic activation of the NMDA receptors increased the cell proliferation and motility. The finding suggests that embryonal carcinoma stem cells can be actively regulated by establishing a glutamatergic autocrine/paracrine niche via releasing and responding to the transmitter. PMID:27322683

  9. FDA Warns About Stem Cell Claims

    MedlinePlus

    ... Home For Consumers Consumer Updates FDA Warns About Stem Cell Claims Share Tweet Linkedin Pin it More sharing ... blood-forming system. back to top Regulation of Stem Cells FDA regulates stem cells in the U.S. to ...

  10. Heparan sulfate regulates the number and centrosome positioning of Drosophila male germline stem cells

    PubMed Central

    Levings, Daniel C.; Arashiro, Takeshi; Nakato, Hiroshi

    2016-01-01

    Stem cell division is tightly controlled via secreted signaling factors and cell adhesion molecules provided from local niche structures. Molecular mechanisms by which each niche component regulates stem cell behaviors remain to be elucidated. Here we show that heparan sulfate (HS), a class of glycosaminoglycan chains, regulates the number and asymmetric division of germline stem cells (GSCs) in the Drosophila testis. We found that GSC number is sensitive to the levels of 6-O sulfate groups on HS. Loss of 6-O sulfation also disrupted normal positioning of centrosomes, a process required for asymmetric division of GSCs. Blocking HS sulfation specifically in the niche, termed the hub, led to increased GSC numbers and mispositioning of centrosomes. The same treatment also perturbed the enrichment of Apc2, a component of the centrosome-anchoring machinery, at the hub–GSC interface. This perturbation of the centrosome-anchoring process ultimately led to an increase in the rate of spindle misorientation and symmetric GSC division. This study shows that specific HS modifications provide a novel regulatory mechanism for stem cell asymmetric division. The results also suggest that HS-mediated niche signaling acts upstream of GSC division orientation control. PMID:26792837

  11. Heparan sulfate regulates the number and centrosome positioning of Drosophila male germline stem cells.

    PubMed

    Levings, Daniel C; Arashiro, Takeshi; Nakato, Hiroshi

    2016-03-15

    Stem cell division is tightly controlled via secreted signaling factors and cell adhesion molecules provided from local niche structures. Molecular mechanisms by which each niche component regulates stem cell behaviors remain to be elucidated. Here we show that heparan sulfate (HS), a class of glycosaminoglycan chains, regulates the number and asymmetric division of germline stem cells (GSCs) in the Drosophila testis. We found that GSC number is sensitive to the levels of 6-O sulfate groups on HS. Loss of 6-O sulfation also disrupted normal positioning of centrosomes, a process required for asymmetric division of GSCs. Blocking HS sulfation specifically in the niche, termed the hub, led to increased GSC numbers and mispositioning of centrosomes. The same treatment also perturbed the enrichment of Apc2, a component of the centrosome-anchoring machinery, at the hub-GSC interface. This perturbation of the centrosome-anchoring process ultimately led to an increase in the rate of spindle misorientation and symmetric GSC division. This study shows that specific HS modifications provide a novel regulatory mechanism for stem cell asymmetric division. The results also suggest that HS-mediated niche signaling acts upstream of GSC division orientation control.

  12. NF-kappaΒ-inducing kinase regulates stem cell phenotype in breast cancer

    PubMed Central

    Vazquez-Santillan, Karla; Melendez-Zajgla, Jorge; Jimenez-Hernandez, Luis Enrique; Gaytan-Cervantes, Javier; Muñoz-Galindo, Laura; Piña-Sanchez, Patricia; Martinez-Ruiz, Gustavo; Torres, Javier; Garcia-Lopez, Patricia; Gonzalez-Torres, Carolina; Ruiz, Victor; Avila-Moreno, Federico; Velasco-Velazquez, Marco; Perez-Tapia, Mayra; Maldonado, Vilma

    2016-01-01

    Breast cancer stem cells (BCSCs) overexpress components of the Nuclear factor-kappa B (NF-κB) signaling cascade and consequently display high NF-κB activity levels. Breast cancer cell lines with high proportion of CSCs exhibit high NF-κB-inducing kinase (NIK) expression. The role of NIK in the phenotype of cancer stem cell regulation is poorly understood. Expression of NIK was analyzed by quantitative RT-PCR in BCSCs. NIK levels were manipulated through transfection of specific shRNAs or an expression vector. The effect of NIK in the cancer stem cell properties was assessed by mammosphere formation, mice xenografts and stem markers expression. BCSCs expressed higher levels of NIK and its inhibition through small hairpin (shRNA), reduced the expression of CSC markers and impaired clonogenicity and tumorigenesis. Genome-wide expression analyses suggested that NIK acts on ERK1/2 pathway to exert its activity. In addition, forced expression of NIK increased the BCSC population and enhanced breast cancer cell tumorigenicity. The in vivo relevance of these results is further supported by a tissue microarray of breast cancer samples in which we observed correlated expression of Aldehyde dehydrogenase (ALDH) and NIK protein. Our results support the essential involvement of NIK in BCSC phenotypic regulation via ERK1/2 and NF-κB. PMID:27876836

  13. NF-kappaΒ-inducing kinase regulates stem cell phenotype in breast cancer.

    PubMed

    Vazquez-Santillan, Karla; Melendez-Zajgla, Jorge; Jimenez-Hernandez, Luis Enrique; Gaytan-Cervantes, Javier; Muñoz-Galindo, Laura; Piña-Sanchez, Patricia; Martinez-Ruiz, Gustavo; Torres, Javier; Garcia-Lopez, Patricia; Gonzalez-Torres, Carolina; Ruiz, Victor; Avila-Moreno, Federico; Velasco-Velazquez, Marco; Perez-Tapia, Mayra; Maldonado, Vilma

    2016-11-23

    Breast cancer stem cells (BCSCs) overexpress components of the Nuclear factor-kappa B (NF-κB) signaling cascade and consequently display high NF-κB activity levels. Breast cancer cell lines with high proportion of CSCs exhibit high NF-κB-inducing kinase (NIK) expression. The role of NIK in the phenotype of cancer stem cell regulation is poorly understood. Expression of NIK was analyzed by quantitative RT-PCR in BCSCs. NIK levels were manipulated through transfection of specific shRNAs or an expression vector. The effect of NIK in the cancer stem cell properties was assessed by mammosphere formation, mice xenografts and stem markers expression. BCSCs expressed higher levels of NIK and its inhibition through small hairpin (shRNA), reduced the expression of CSC markers and impaired clonogenicity and tumorigenesis. Genome-wide expression analyses suggested that NIK acts on ERK1/2 pathway to exert its activity. In addition, forced expression of NIK increased the BCSC population and enhanced breast cancer cell tumorigenicity. The in vivo relevance of these results is further supported by a tissue microarray of breast cancer samples in which we observed correlated expression of Aldehyde dehydrogenase (ALDH) and NIK protein. Our results support the essential involvement of NIK in BCSC phenotypic regulation via ERK1/2 and NF-κB.

  14. TRIM28 multi-domain protein regulates cancer stem cell population in breast tumor development

    PubMed Central

    Czerwińska, Patrycja; Shah, Parantu K.; Tomczak, Katarzyna; Klimczak, Marta; Mazurek, Sylwia; Sozańska, Barbara; Biecek, Przemysław; Korski, Konstanty; Filas, Violetta; Mackiewicz, Andrzej; Andersen, Jannik N.; Wiznerowicz, Maciej

    2017-01-01

    The expression of Tripartite motif-containing protein 28 (TRIM28)/Krüppel-associated box (KRAB)-associated protein 1 (KAP1), is elevated in at least 14 tumor types, including solid and hematopoietic tumors. High level of TRIM28 is associated with triple-negative subtype of breast cancer (TNBC), which shows higher aggressiveness and lower survival rates. Interestingly, TRIM28 is essential for maintaining the pluripotent phenotype in embryonic stem cells. Following on that finding, we evaluated the role of TRIM28 protein in the regulation of breast cancer stem cells (CSC) populations and tumorigenesis in vitro and in vivo. Downregulation of TRIM28 expression in xenografts led to deceased expression of pluripotency and mesenchymal markers, as well as inhibition of signaling pathways involved in the complex mechanism of CSC maintenance. Moreover, TRIM28 depletion reduced the ability of cancer cells to induce tumor growth when subcutaneously injected in limiting dilutions. Our data demonstrate that the downregulation of TRIM28 gene expression reduced the ability of CSCs to self-renew that resulted in significant reduction of tumor growth. Loss of function of TRIM28 leads to dysregulation of cell cycle, cellular response to stress, cancer cell metabolism, and inhibition of oxidative phosphorylation. All these mechanisms directly regulate maintenance of CSC population. Our original results revealed the role of the TRIM28 in regulating the CSC population in breast cancer. These findings may pave the way to novel and more effective therapies targeting cancer stem cells in breast tumors. PMID:27845900

  15. Cryptotanshinone targets tumor-initiating cells through down-regulation of stemness genes expression

    PubMed Central

    ZHANG, YING; CABARCAS, STEPHANIE M.; ZHENG, JI; SUN, LEI; MATHEWS, LESLEY A.; ZHANG, XIAOHU; LIN, HONGSHENG; FARRAR, WILLIAM L.

    2016-01-01

    Recent evidence indicates that tumor-initiating cells (TICs), also called cancer stem cells (CSCs), are responsible for tumor initiation and progression, therefore representing an important cell population that may be used as a target for the development of future anticancer therapies. In the present study, Cryptotanshinone (CT), a traditional Chinese herbal medicine, was demonstrated to regulate the behaviors of LNCaP prostate cells and prostate LNCaP TICs. The results demonstrate that treatment with CT alters cellular proliferation, cell cycle status, migration, viability, colony formation and notably, sphere formation and down-regulation of stemness genes (Nanog, OCT4, SOX2, β-catenin, CXCR4) in TICs. The present study demonstrates that CT targets the LNCaP CD44+CD24- population that is representative of prostate TICs and also affects total LNCaP cells as well via down-regulation of stemness genes. The strong effect with which CT has on prostate TICs suggests that CT may potentially function as a novel natural anticancer agent that specifically targets TICs. PMID:27313698

  16. BRD4 regulates Nanog expression in mouse embryonic stem cells and preimplantation embryos.

    PubMed

    Liu, W; Stein, P; Cheng, X; Yang, W; Shao, N-Y; Morrisey, E E; Schultz, R M; You, J

    2014-12-01

    Bromodomain-containing protein 4 (BRD4) is an important epigenetic reader implicated in the pathogenesis of a number of different cancers and other diseases. Brd4-null mouse embryos die shortly after implantation and are compromised in their ability to maintain the inner cell mass, which gives rise to embryonic stem cells (ESCs). Here we report that BRD4 regulates expression of the pluripotency factor Nanog in mouse ESCs and preimplantation embryos, as well as in human ESCs and embryonic cancer stem cells. Inhibition of BRD4 function using a chemical inhibitor, small interfering RNAs, or a dominant-negative approach suppresses Nanog expression, and abolishes the self-renewal ability of ESCs. We also find that BRD4 associates with BRG1 (brahma-related gene 1, aka Smarca4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4)), a key regulator of ESC self-renewal and pluripotency, in the Nanog regulatory regions to regulate Nanog expression. Our study identifies Nanog as a novel BRD4 target gene, providing new insights for the biological function of BRD4 in stem cells and mouse embryos. Knowledge gained from these non-cancerous systems will facilitate future investigations of how Brd4 dysfunction leads to cancers.

  17. Regulation of organogenesis and stem cell properties by T-box transcription factors.

    PubMed

    Takashima, Yasuo; Suzuki, Atsushi

    2013-10-01

    T-box transcription factors containing the common DNA-binding domain T-box contribute to the organization of multiple tissues in vertebrates and invertebrates. In mammals, 17 T-box genes are divided into five subfamilies depending on their amino acid homology. The proper distribution and expression of individual T-box transcription factors in different tissues enable regulation of the proliferation and differentiation of tissue-specific stem cells and progenitor cells in a suitable time schedule for tissue organization. Consequently, uncontrollable expressions of T-box genes induce abnormal tissue organization, and eventually cause various diseases with malformation and malfunction of tissues and organs. Furthermore, some T-box transcription factors are essential for maintaining embryonic stem cell pluripotency, improving the quality of induced pluripotent stem cells, and inducing cell-lineage conversion of differentiated cells. These lines of evidence indicate fundamental roles of T-box transcription factors in tissue organization and stem cell properties, and suggest that these transcription factors will be useful for developing therapeutic approaches in regenerative medicine.

  18. Regulation of hematopoietic and leukemic stem cells by the immune system.

    PubMed

    Riether, C; Schürch, C M; Ochsenbein, A F

    2015-02-01

    Hematopoietic stem cells (HSCs) are rare, multipotent cells that generate via progenitor and precursor cells of all blood lineages. Similar to normal hematopoiesis, leukemia is also hierarchically organized and a subpopulation of leukemic cells, the leukemic stem cells (LSCs), is responsible for disease initiation and maintenance and gives rise to more differentiated malignant cells. Although genetically abnormal, LSCs share many characteristics with normal HSCs, including quiescence, multipotency and self-renewal. Normal HSCs reside in a specialized microenvironment in the bone marrow (BM), the so-called HSC niche that crucially regulates HSC survival and function. Many cell types including osteoblastic, perivascular, endothelial and mesenchymal cells contribute to the HSC niche. In addition, the BM functions as primary and secondary lymphoid organ and hosts various mature immune cell types, including T and B cells, dendritic cells and macrophages that contribute to the HSC niche. Signals derived from the HSC niche are necessary to regulate demand-adapted responses of HSCs and progenitor cells after BM stress or during infection. LSCs occupy similar niches and depend on signals from the BM microenvironment. However, in addition to the cell types that constitute the HSC niche during homeostasis, in leukemia the BM is infiltrated by activated leukemia-specific immune cells. Leukemic cells express different antigens that are able to activate CD4(+) and CD8(+) T cells. It is well documented that activated T cells can contribute to the control of leukemic cells and it was hoped that these cells may be able to target and eliminate the therapy-resistant LSCs. However, the actual interaction of leukemia-specific T cells with LSCs remains ill-defined. Paradoxically, many immune mechanisms that evolved to activate emergency hematopoiesis during infection may actually contribute to the expansion and differentiation of LSCs, promoting leukemia progression. In this review, we

  19. Health consumers and stem cell therapy innovation: markets, models and regulation.

    PubMed

    Salter, Brian; Zhou, Yinhua; Datta, Saheli

    2014-05-01

    Global health consumer demand for stem cell therapies is vibrant, but the supply of treatments from the conventional science-based model of innovation is small and unlikely to increase in the near future. At the same time, several models of medical innovation have emerged that can respond to the demand, often employing a transnational value chain to deliver the product. Much of the commentary has approached the issue from a supply side perspective, demonstrating the extent to which national and transnational regulation fails to impose what are regarded as appropriate standards on the 'illicit' supply of stem cell therapies characterized by little data and poor outcomes. By contrast, this article presents a political economic analysis with a strong demand side perspective, arguing that the problem of what is termed 'stem cell tourism' is embedded in the demand-supply relationship of the health consumer market and its engagement with different types of stem cell therapy innovation. To be meaningful, discussions of regulation must recognize that analysis or risk being sidelined by a market, which ignores their often wishful thinking.

  20. The regulation of hematopoietic stem cell collection and storage: the New York State approach.

    PubMed

    Ciavarella, D; Linden, J V

    1992-01-01

    In December 1988, the New York State (NYS) regulatory code on bone marrow banking went into effect. The goals of the regulations were to codify a high standard of practice, to prohibit charlatanism in the practice or promotion of stem cell banking, and to promote legitimate research. The NYS approach modeled the stem cell regulatory language after that already established for blood banks and clinical laboratories. Also, the stem cell standards are an element of standards applicable to all tissue banks, developed as a result of a comprehensive transplant law enacted in NYS in 1990. The code itself, published as an addendum to this article, mandates that a qualified (by training and experience) medical director and medical advisory committee be appointed, and gives broad and complete responsibility for the services provided to that medical director. Explicit written policies and procedures regarding administrative, technical, safety, and quality issues are necessary, but regulatory micromanagement of the laboratory was avoided by limiting detailed procedural requirements. We believe that these regulations have contributed to the quality and safety of stem cell-related therapies in NYS.

  1. Fip1 regulates mRNA alternative polyadenylation to promote stem cell self-renewal

    PubMed Central

    Lackford, Brad; Yao, Chengguo; Charles, Georgette M; Weng, Lingjie; Zheng, Xiaofeng; Choi, Eun-A; Xie, Xiaohui; Wan, Ji; Xing, Yi; Freudenberg, Johannes M; Yang, Pengyi; Jothi, Raja; Hu, Guang; Shi, Yongsheng

    2014-01-01

    mRNA alternative polyadenylation (APA) plays a critical role in post-transcriptional gene control and is highly regulated during development and disease. However, the regulatory mechanisms and functional consequences of APA remain poorly understood. Here, we show that an mRNA 3′ processing factor, Fip1, is essential for embryonic stem cell (ESC) self-renewal and somatic cell reprogramming. Fip1 promotes stem cell maintenance, in part, by activating the ESC-specific APA profiles to ensure the optimal expression of a specific set of genes, including critical self-renewal factors. Fip1 expression and the Fip1-dependent APA program change during ESC differentiation and are restored to an ESC-like state during somatic reprogramming. Mechanistically, we provide evidence that the specificity of Fip1-mediated APA regulation depends on multiple factors, including Fip1-RNA interactions and the distance between APA sites. Together, our data highlight the role for post-transcriptional control in stem cell self-renewal, provide mechanistic insight on APA regulation in development, and establish an important function for APA in cell fate specification. PMID:24596251

  2. Distinct mechanisms regulate Cdx2 expression in the blastocyst and in trophoblast stem cells

    PubMed Central

    Rayon, Teresa; Menchero, Sergio; Rollán, Isabel; Ors, Inmaculada; Helness, Anne; Crespo, Miguel; Nieto, Andres; Azuara, Véronique; Rossant, Janet; Manzanares, Miguel

    2016-01-01

    The first intercellular differences during mammalian embryogenesis arise in the blastocyst, producing the inner cell mass and the trophectoderm. The trophectoderm is the first extraembryonic tissue and does not contribute to the embryo proper, its differentiation instead forming tissues that sustain embryonic development. Crucial roles in extraembryonic differentiation have been identified for certain transcription factors, but a comprehensive picture of the regulation of this early specification is still lacking. Here, we investigated whether the regulatory mechanisms involved in Cdx2 expression in the blastocyst are also utilized in the postimplantation embryo. We analyzed an enhancer that is regulated through Hippo and Notch in the blastocyst trophectoderm, unexpectedly finding that it is inactive in the extraembryonic structures at postimplantation stages. Further analysis identified other Cdx2 regulatory elements including a stem-cell specific regulatory sequence and an element that drives reporter expression in the trophectoderm, a subset of cells in the extraembryonic region of the postimplantation embryo and in trophoblast stem cells. The cross-comparison in this study of cis-regulatory elements employed in the blastocyst, stem cell populations and the postimplantation embryo provides new insights into early mammalian development and suggests a two-step mechanism in Cdx2 regulation. PMID:27256674

  3. Distinct mechanisms regulate Cdx2 expression in the blastocyst and in trophoblast stem cells.

    PubMed

    Rayon, Teresa; Menchero, Sergio; Rollán, Isabel; Ors, Inmaculada; Helness, Anne; Crespo, Miguel; Nieto, Andres; Azuara, Véronique; Rossant, Janet; Manzanares, Miguel

    2016-06-03

    The first intercellular differences during mammalian embryogenesis arise in the blastocyst, producing the inner cell mass and the trophectoderm. The trophectoderm is the first extraembryonic tissue and does not contribute to the embryo proper, its differentiation instead forming tissues that sustain embryonic development. Crucial roles in extraembryonic differentiation have been identified for certain transcription factors, but a comprehensive picture of the regulation of this early specification is still lacking. Here, we investigated whether the regulatory mechanisms involved in Cdx2 expression in the blastocyst are also utilized in the postimplantation embryo. We analyzed an enhancer that is regulated through Hippo and Notch in the blastocyst trophectoderm, unexpectedly finding that it is inactive in the extraembryonic structures at postimplantation stages. Further analysis identified other Cdx2 regulatory elements including a stem-cell specific regulatory sequence and an element that drives reporter expression in the trophectoderm, a subset of cells in the extraembryonic region of the postimplantation embryo and in trophoblast stem cells. The cross-comparison in this study of cis-regulatory elements employed in the blastocyst, stem cell populations and the postimplantation embryo provides new insights into early mammalian development and suggests a two-step mechanism in Cdx2 regulation.

  4. Cytoskeletal to Nuclear Strain Transfer Regulates YAP Signaling in Mesenchymal Stem Cells

    PubMed Central

    Driscoll, Tristan P.; Cosgrove, Brian D.; Heo, Su-Jin; Shurden, Zach E.; Mauck, Robert L.

    2015-01-01

    Mechanical forces transduced to cells through the extracellular matrix are critical regulators of tissue development, growth, and homeostasis, and can play important roles in directing stem cell differentiation. In addition to force-sensing mechanisms that reside at the cell surface, there is growing evidence that forces transmitted through the cytoskeleton and to the nuclear envelope are important for mechanosensing, including activation of the Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) pathway. Moreover, nuclear shape, mechanics, and deformability change with differentiation state and have been likewise implicated in force sensing and differentiation. However, the significance of force transfer to the nucleus through the mechanosensing cytoskeletal machinery in the regulation of mesenchymal stem cell mechanobiologic response remains unclear. Here we report that actomyosin-generated cytoskeletal tension regulates nuclear shape and force transmission through the cytoskeleton and demonstrate the differential short- and long-term response of mesenchymal stem cells to dynamic tensile loading based on the contractility state, the patency of the actin cytoskeleton, and the connections it makes with the nucleus. Specifically, we show that while some mechanoactive signaling pathways (e.g., ERK signaling) can be activated in the absence of nuclear strain transfer, cytoskeletal strain transfer to the nucleus is essential for activation of the YAP/TAZ pathway with stretch. PMID:26083918

  5. SWI/SNF-directed stem cell lineage specification: dynamic composition regulates specific stages of skeletal myogenesis

    PubMed Central

    Toto, Paula Coutinho; Puri, Pier Lorenzo; Albini, Sonia

    2016-01-01

    SWI/SNF chromatin-remodeling complexes are key regulators of the epigenetic modifications that determine whether stem cells maintain pluripotency or commit toward specific lineages through development and during postnatal life. Dynamic combinatorial assembly of multiple variants of SWI/SNF subunits is emerging as the major determinant of the functional versatility of SWI/SNF. Here, we summarize the current knowledge on the structural and functional properties of the alternative SWI/SNF complexes that direct stem cell fate toward skeletal muscle lineage and control distinct stages of skeletal myogenesis. In particular, we will refer to recent evidence pointing to the essential role of two SWI/SNF components not expressed in embryonic stem cells—the catalytic subunit BRM and the structural component BAF60C—whose induction in muscle progenitors coincides with the expansion of their transcriptional repertoire. PMID:27207468

  6. Epigenetic regulation in pluripotent stem cells: a key to breaking the epigenetic barrier.

    PubMed

    Watanabe, Akira; Yamada, Yasuhiro; Yamanaka, Shinya

    2013-01-05

    The differentiation and reprogramming of cells are accompanied by drastic changes in the epigenetic profiles of cells. Waddington's classical model clearly describes how differentiating cells acquire their cell identity as the developmental potential of an individual cell population declines towards the terminally differentiated state. The recent discovery of induced pluripotent stem cells as well as of somatic cell nuclear transfer provided evidence that the process of differentiation can be reversed. The identity of somatic cells is strictly protected by an epigenetic barrier, and these cells acquire pluripotency by breaking the epigenetic barrier by reprogramming factors such as Oct3/4, Sox2, Klf4, Myc and LIN28. This review covers the current understanding of the spatio-temporal regulation of epigenetics in pluripotent and differentiated cells, and discusses how cells determine their identity and overcome the epigenetic barrier during the reprogramming process.

  7. Multi-layered environmental regulation on the homeostasis of stem cells: the saga of hair growth and alopecia.

    PubMed

    Chen, Chih-Chiang; Chuong, Cheng Ming

    2012-04-01

    Stem cells are fascinating because of their potential in regenerative medicine. Stem cell homeostasis has been thought to be mainly regulated by signals from their adjacent micro-environment named the "stem cell niche". However, recent studies reveal that there can be multiple layers of environmental controls. Here we review these environmental controls using the paradigm of hair stem cells, because to observe and analyze the growth of hair is easier due to their characteristic cyclic regeneration pattern. The length of hair fibers is regulated by the duration of the growth period. In the hair follicles, hair stem cells located in the follicle bulge interact with signals from the dermal papilla. Outside of the follicle, activation of hair stem cells has been shown to be modulated by molecules released from the intra-dermal adipose tissue as well as body hormone status, immune function, neural activities, and aging. The general physiological status of an individual is further influenced by circadian rhythms and changing seasons. The interactive networks of these environmental factors provide new understanding on how stem cell homeostasis is regulated, inspiring new insights for regenerative medicine. Therapies do not necessarily have to be achieved by using stem cells themselves which may constitute a higher risk but by modulating stem cell activity through targeting one or multiple layers of their micro- and macro-environments.

  8. Multi-layered environmental regulation on the homeostasis of stem cells: The saga of hair growth and alopecia

    PubMed Central

    Chen, Chih-Chiang; Chuong, Cheng Ming

    2013-01-01

    Stem cells are fascinating because of their potential in regenerative medicine. Stem cell homeostasis has been thought to be mainly regulated by signals from their adjacent micro-environment named the “stem cell niche”. However, recent studies reveal that there can be multiple layers of environmental controls. Here we review these environmental controls using the paradigm of hair stem cells, because to observe and analyze the growth of hair is easier due to their characteristic cyclic regeneration pattern. The length of hair fibers is regulated by the duration of the growth period. In the hair follicles, hair stem cells located in the follicle bulge interact with signals from the dermal papilla. Outside of the follicle, activation of hair stem cells has been shown to be modulated by molecules released from the intra-dermal adipose tissue as well as body hormone status, immune function, neural activities, and aging. The general physiological status of an individual is further influenced by circadian rhythms and changing seasons. The interactive networks of these environmental factors provide new understanding on how stem cell homeostasis is regulated, inspiring new insights for regenerative medicine. Therapies do not necessarily have to be achieved by using stem cells themselves which may constitute a higher risk but by modulating stem cell activity through targeting one or multiple layers of their micro- and macro-environments. PMID:22391240

  9. Regulating RNA polymerase pausing and transcription elongation in embryonic stem cells.

    PubMed

    Min, Irene M; Waterfall, Joshua J; Core, Leighton J; Munroe, Robert J; Schimenti, John; Lis, John T

    2011-04-01

    Transitions between pluripotent stem cells and differentiated cells are executed by key transcription regulators. Comparative measurements of RNA polymerase distribution over the genome's primary transcription units in different cell states can identify the genes and steps in the transcription cycle that are regulated during such transitions. To identify the complete transcriptional profiles of RNA polymerases with high sensitivity and resolution, as well as the critical regulated steps upon which regulatory factors act, we used genome-wide nuclear run-on (GRO-seq) to map the density and orientation of transcriptionally engaged RNA polymerases in mouse embryonic stem cells (ESCs) and mouse embryonic fibroblasts (MEFs). In both cell types, progression of a promoter-proximal, paused RNA polymerase II (Pol II) into productive elongation is a rate-limiting step in transcription of ∼40% of mRNA-encoding genes. Importantly, quantitative comparisons between cell types reveal that transcription is controlled frequently at paused Pol II's entry into elongation. Furthermore, "bivalent" ESC genes (exhibiting both active and repressive histone modifications) bound by Polycomb group complexes PRC1 (Polycomb-repressive complex 1) and PRC2 show dramatically reduced levels of paused Pol II at promoters relative to an average gene. In contrast, bivalent promoters bound by only PRC2 allow Pol II pausing, but it is confined to extremely 5' proximal regions. Altogether, these findings identify rate-limiting targets for transcription regulation during cell differentiation.

  10. Snail/Slug-YAP/TAZ complexes cooperatively regulate mesenchymal stem cell function and bone formation.

    PubMed

    Tang, Yi; Weiss, Stephen J

    2017-03-04

    Snail and Slug are zinc-finger transcription factors that play key roles in directing the epithelial-mesenchymal transition (EMT) programs associated with normal development as well as disease progression. More recent work suggests that these EMT-associated transcription factors also modulate the function of both embryonic and adult stem cells. Interestingly, YAP and TAZ, the co-transcriptional effectors of the Hippo pathway, likewise play an important role in stem cell self-renewal and lineage commitment. While direct intersections between the Snail/Slug and Hippo pathways have not been described previously, we recently described an unexpected cooperative interaction between Snail/Slug and YAP/TAZ that controls the self-renewal and differentiation properties of bone marrow-derived mesenchymal stem cells (MSCs), a cell population critical to bone development. Additional studies revealed that both Snail and Slug are able to form binary complexes with either YAP or TAZ that, together, control YAP/TAZ transcriptional activity and function throughout mouse development. Given the more recent observations that MSC-like cell populations are found in association throughout the vasculature where they participate in tissue regeneration, fibrosis and cancer, the Snail/Slug-YAP/TAZ axis is well-positioned to regulate global stem cell function in health and disease.

  11. Regulation of Hematopoietic Stem Cell Behavior by the Nanostructured Presentation of Extracellular Matrix Components

    PubMed Central

    Muth, Christine Anna; Steinl, Carolin; Klein, Gerd; Lee-Thedieck, Cornelia

    2013-01-01

    Hematopoietic stem cells (HSCs) are maintained in stem cell niches, which regulate stem cell fate. Extracellular matrix (ECM) molecules, which are an essential part of these niches, can actively modulate cell functions. However, only little is known on the impact of ECM ligands on HSCs in a biomimetic environment defined on the nanometer-scale level. Here, we show that human hematopoietic stem and progenitor cell (HSPC) adhesion depends on the type of ligand, i.e., the type of ECM molecule, and the lateral, nanometer-scaled distance between the ligands (while the ligand type influenced the dependency on the latter). For small fibronectin (FN)–derived peptide ligands such as RGD and LDV the critical adhesive interligand distance for HSPCs was below 45 nm. FN-derived (FN type III 7–10) and osteopontin-derived protein domains also supported cell adhesion at greater distances. We found that the expression of the ECM protein thrombospondin-2 (THBS2) in HSPCs depends on the presence of the ligand type and its nanostructured presentation. Functionally, THBS2 proved to mediate adhesion of HSPCs. In conclusion, the present study shows that HSPCs are sensitive to the nanostructure of their microenvironment and that they are able to actively modulate their environment by secreting ECM factors. PMID:23405094

  12. Regulation of Breast Cancer Stem Cells by Tissue Rigidity

    DTIC Science & Technology

    2015-06-01

    EPH4Ras cells shows that knocking down Twist 1 prevented loosing of adherent jllllctions as evident by E-cadhetin (green) membrane localization. 5 EMT...knockdown ofTwistl, but not Snail2, prevented the EMT-like invasive phenotype induced by the stiff matrix stiffness of 5700Pa; instead these mamma1y...Fig. Ib and Supplementary Fig. lB- D). Knockdown of TWTSTl prevented the invasive phenotype at 5,700Pa; instead, these cells formed basally

  13. The role of osteoblasts in regulating hematopoietic stem cell activity and tumor metastasis.

    PubMed

    Neiva, K; Sun, Y-X; Taichman, R S

    2005-10-01

    Bone marrow stromal cells are critical regulators of hematopoiesis. Osteoblasts are part of the stromal cell support system in bone marrow and may be derived from a common precursor. Several studies suggested that osteoblasts regulate hematopoiesis, yet the entire mechanism is not understood. It is clear, however, that both hematopoietic precursors and osteoblasts interact for the production of osteoclasts and the activation of resorption. We observed that hematopoietic stem cells (HSCs) regulate osteoblastic secretion of various growth factors, and that osteoblasts express some soluble factors exclusively in the presence of HSCs. Osteoblasts and hematopoietic cells are closely associated with each other in the bone marrow, suggesting a reciprocal relationship between them to develop the HSC niche. One critical component regulating the niche is stromal-derived factor-1 (SDF-1) and its receptor CXCR4 which regulates stem cell homing and, as we have recently demonstrated, plays a crucial role in facilitating those tumors which metastasize to bone. Osteoblasts produce abundant amounts of SDF-1 and therefore osteoblasts play an important role in metastasis. These findings are discussed in the context of the role of osteoblasts in marrow function in health and disease.

  14. PPARβ/δ: A master regulator of mesenchymal stem cell functions.

    PubMed

    Djouad, Farida; Ipseiz, Natacha; Luz-Crawford, Patricia; Scholtysek, Carina; Krönke, Gerhard; Jorgensen, Christian

    2016-11-30

    Peroxisome proliferator-activated receptors (PPARs) have emerged as key regulators of physiological and immunological processes. Recently, one of their members PPARβ/δ has been identified as major player in the maintenance of bone homeostasis, by promoting Wnt signalling activity in osteoblast and mesenchymal stem cells (MSC). PPARβ/δ not only controls the fate of MSC but also regulates their immunosuppressive properties by directly modulating their NF-κB activity. In this review, we discuss how the regulation of PPARβ/δ provides an innovative strategy for an optimisation of MSC-based therapy.

  15. Identification of MicroRNAs Regulating Reprogramming Factor LIN28 in Embryonic Stem Cells and Cancer Cells*

    PubMed Central

    Zhong, Xiaomin; Li, Ning; Liang, Shun; Huang, Qihong; Coukos, George; Zhang, Lin

    2010-01-01

    LIN28 (a homologue of the Caenorhabditis elegans lin-28 gene) is an evolutionarily conserved RNA-binding protein and a master regulator controlling the pluripotency of embryonic stem cells. Together with OCT4, SOX2, and NANOG, LIN28 can reprogram somatic cells, producing induced pluripotent stem cells. Expression of LIN28 is highly restricted to embryonic stem cells and developing tissues. In human tumors, LIN28 is up-regulated and functions as an oncogene promoting malignant transformation and tumor progression. However, the mechanisms of transcriptional and post-transcriptional regulation of LIN28 are still largely unknown. To examine microRNAs (miRNAs) that repress LIN28 expression, a combined in silico prediction and miRNA library screening approach was used in the present study. Four miRNAs directly regulating LIN28 (let-7, mir-125, mir-9, and mir-30) were initially identified by this approach and further validated by quantitative RT-PCR, Western blot analysis, and a LIN28 3′-UTR reporter assay. We found that expression levels of these four miRNAs were clustered together and inversely correlated with LIN28 expression during embryonic stem cell differentiation. In addition, the expression of these miRNAs was remarkably lower in LIN28-positive tumor cells compared with LIN28-negative tumor cells. Importantly, we demonstrated that these miRNAs were able to regulate the expression and activity of let-7, mediated by LIN28. Taken together, our studies demonstrate that miRNAs let-7, mir-125, mir-9, and mir-30 directly repress LIN28 expression in embryonic stem and cancer cells. Global down-regulation of these miRNAs may be one of the mechanisms of LIN28 reactivation in human cancers. PMID:20947512

  16. Identification of microRNAs regulating reprogramming factor LIN28 in embryonic stem cells and cancer cells.

    PubMed

    Zhong, Xiaomin; Li, Ning; Liang, Shun; Huang, Qihong; Coukos, George; Zhang, Lin

    2010-12-31

    LIN28 (a homologue of the Caenorhabditis elegans lin-28 gene) is an evolutionarily conserved RNA-binding protein and a master regulator controlling the pluripotency of embryonic stem cells. Together with OCT4, SOX2, and NANOG, LIN28 can reprogram somatic cells, producing induced pluripotent stem cells. Expression of LIN28 is highly restricted to embryonic stem cells and developing tissues. In human tumors, LIN28 is up-regulated and functions as an oncogene promoting malignant transformation and tumor progression. However, the mechanisms of transcriptional and post-transcriptional regulation of LIN28 are still largely unknown. To examine microRNAs (miRNAs) that repress LIN28 expression, a combined in silico prediction and miRNA library screening approach was used in the present study. Four miRNAs directly regulating LIN28 (let-7, mir-125, mir-9, and mir-30) were initially identified by this approach and further validated by quantitative RT-PCR, Western blot analysis, and a LIN28 3'-UTR reporter assay. We found that expression levels of these four miRNAs were clustered together and inversely correlated with LIN28 expression during embryonic stem cell differentiation. In addition, the expression of these miRNAs was remarkably lower in LIN28-positive tumor cells compared with LIN28-negative tumor cells. Importantly, we demonstrated that these miRNAs were able to regulate the expression and activity of let-7, mediated by LIN28. Taken together, our studies demonstrate that miRNAs let-7, mir-125, mir-9, and mir-30 directly repress LIN28 expression in embryonic stem and cancer cells. Global down-regulation of these miRNAs may be one of the mechanisms of LIN28 reactivation in human cancers.

  17. TC1(C8orf4) regulates hematopoietic stem/progenitor cells and hematopoiesis.

    PubMed

    Jung, Yusun; Kim, Minsung; Soh, Hyunsu; Lee, Soyoung; Kim, Jungtae; Park, Surim; Song, Kyuyoung; Lee, Inchul

    2014-01-01

    Hematopoiesis is a complex process requiring multiple regulators for hematopoietic stem/progenitor cells (HSPC) and differentiation to multi-lineage blood cells. TC1(C8orf4) is implicated in cancers, hematological malignancies and inflammatory activation. Here, we report that Tc1 regulates hematopoiesis in mice. Myeloid and lymphoid cells are increased markedly in peripheral blood of Tc1-deleted mice compared to wild type controls. Red blood cells are small-sized but increased in number. The bone marrow of Tc1-/- mice is normocellular histologically. However, Lin-Sca-1+c-Kit+ (LSK) cells are expanded in Tc1-/- mice compared to wild type controls. The expanded population mostly consists of CD150-CD48+ cells, suggesting the expansion of lineage-restricted hematopoietic progenitor cells. Colony forming units (CFU) are increased in Tc1-/- mice bone marrow cells compared to controls. In wild type mice bone marrow, Tc1 is expressed in a limited population of HSPC but not in differentiated cells. Major myeloid transcriptional regulators such as Pu.1 and Cebpα are not up-regulated in Tc1-/- mice bone marrow. Our findings indicate that TC1 is a novel hematopoietic regulator. The mechanisms of TC1-dependent HSPC regulation and lineage determination are unknown.

  18. Different requirements for conserved post-transcriptional regulators in planarian regeneration and stem cell maintenance.

    PubMed

    Rouhana, Labib; Shibata, Norito; Nishimura, Osamu; Agata, Kiyokazu

    2010-05-15

    Planarian regeneration depends on the presence and precise regulation of pluripotent adult somatic stem cells named neoblasts, which differentiate to replace cells of any missing tissue. A characteristic feature of neoblasts is the presence of large perinuclear nonmembranous organelles named "chromatoid bodies", which are comparable to ribonucleoprotein structures found in germ cells of organisms across different phyla. In order to better understand regulation of gene expression in neoblasts, and potentially the function and composition of chromatoid bodies, we characterized homologues to known germ and soma ribonucleoprotein granule components from other organisms and analyzed their function during regeneration of the planarian Dugesia japonica. Expression in neoblasts was detected for 49 of 55 analyzed genes, highlighting the prevalence of post-transcriptional regulation in planarian stem cells. RNAi-mediated knockdown of two factors [ago-2 and bruli] lead to loss of neoblasts, and consequently loss of regeneration, corroborating with results previously reported for a bruli ortholog in the planarian Schmidtea mediterranea (Guo et al., 2006). Conversely, depletion mRNA turnover factors [edc-4 or upf-1], exoribonucleases [xrn-1 or xrn-2], or DEAD box RNA helicases [Djcbc-1 or vas-1] inhibited planarian regeneration, but did not reduce neoblast proliferation or abundance. We also found that depletion of cap-dependent translation initiation factors eIF-3A or eIF-2A interrupted cell cycle progression outside the M-phase of mitosis. Our results show that a set of post-transcriptional regulators is required to maintain the stem cell identity in neoblasts, while another facilitates proper differentiation. We propose that planarian neoblasts maintain pluripotency by employing mechanisms of post-transcriptional regulation exhibited in germ cells and early development of most metazoans. Copyright 2010 Elsevier Inc. All rights reserved.

  19. Identification of cisplatin-regulated metabolic pathways in pluripotent stem cells.

    PubMed

    von Stechow, Louise; Ruiz-Aracama, Ainhoa; van de Water, Bob; Peijnenburg, Ad; Danen, Erik; Lommen, Arjen

    2013-01-01

    The chemotherapeutic compound, cisplatin causes various kinds of DNA lesions but also triggers other pertubations, such as ER and oxidative stress. We and others have shown that treatment of pluripotent stem cells with cisplatin causes a plethora of transcriptional and post-translational alterations that, to a major extent, point to DNA damage response (DDR) signaling. The orchestrated DDR signaling network is important to arrest the cell cycle and repair the lesions or, in case of damage beyond repair, eliminate affected cells. Failure to properly balance the various aspects of the DDR in stem cells contributes to ageing and cancer. Here, we performed metabolic profiling by mass spectrometry of embryonic stem (ES) cells treated for different time periods with cisplatin. We then integrated metabolomics with transcriptomics analyses and connected cisplatin-regulated metabolites with regulated metabolic enzymes to identify enriched metabolic pathways. These included nucleotide metabolism, urea cycle and arginine and proline metabolism. Silencing of identified proline metabolic and catabolic enzymes indicated that altered proline metabolism serves as an adaptive, rather than a toxic response. A group of enriched metabolic pathways clustered around the metabolite S-adenosylmethionine, which is a hub for methylation and transsulfuration reactions and polyamine metabolism. Enzymes and metabolites with pro- or anti-oxidant functions were also enriched but enhanced levels of reactive oxygen species were not measured in cisplatin-treated ES cells. Lastly, a number of the differentially regulated metabolic enzymes were identified as target genes of the transcription factor p53, pointing to p53-mediated alterations in metabolism in response to genotoxic stress. Altogether, our findings reveal interconnecting metabolic pathways that are responsive to cisplatin and may serve as signaling modules in the DDR in pluripotent stem cells.

  20. Identification of Cisplatin-Regulated Metabolic Pathways in Pluripotent Stem Cells

    PubMed Central

    van de Water, Bob; Peijnenburg, Ad; Danen, Erik; Lommen, Arjen

    2013-01-01

    The chemotherapeutic compound, cisplatin causes various kinds of DNA lesions but also triggers other pertubations, such as ER and oxidative stress. We and others have shown that treatment of pluripotent stem cells with cisplatin causes a plethora of transcriptional and post-translational alterations that, to a major extent, point to DNA damage response (DDR) signaling. The orchestrated DDR signaling network is important to arrest the cell cycle and repair the lesions or, in case of damage beyond repair, eliminate affected cells. Failure to properly balance the various aspects of the DDR in stem cells contributes to ageing and cancer. Here, we performed metabolic profiling by mass spectrometry of embryonic stem (ES) cells treated for different time periods with cisplatin. We then integrated metabolomics with transcriptomics analyses and connected cisplatin-regulated metabolites with regulated metabolic enzymes to identify enriched metabolic pathways. These included nucleotide metabolism, urea cycle and arginine and proline metabolism. Silencing of identified proline metabolic and catabolic enzymes indicated that altered proline metabolism serves as an adaptive, rather than a toxic response. A group of enriched metabolic pathways clustered around the metabolite S-adenosylmethionine, which is a hub for methylation and transsulfuration reactions and polyamine metabolism. Enzymes and metabolites with pro- or anti-oxidant functions were also enriched but enhanced levels of reactive oxygen species were not measured in cisplatin-treated ES cells. Lastly, a number of the differentially regulated metabolic enzymes were identified as target genes of the transcription factor p53, pointing to p53-mediated alterations in metabolism in response to genotoxic stress. Altogether, our findings reveal interconnecting metabolic pathways that are responsive to cisplatin and may serve as signaling modules in the DDR in pluripotent stem cells. PMID:24146875

  1. Gene Expression Profiling of Muscle Stem Cells Identifies Novel Regulators of Postnatal Myogenesis

    PubMed Central

    Alonso-Martin, Sonia; Rochat, Anne; Mademtzoglou, Despoina; Morais, Jessica; de Reyniès, Aurélien; Auradé, Frédéric; Chang, Ted Hung-Tse; Zammit, Peter S.; Relaix, Frédéric

    2016-01-01

    Skeletal muscle growth and regeneration require a population of muscle stem cells, the satellite cells, located in close contact to the myofiber. These cells are specified during fetal and early postnatal development in mice from a Pax3/7 population of embryonic progenitor cells. As little is known about the genetic control of their formation and maintenance, we performed a genome-wide chronological expression profile identifying the dynamic transcriptomic changes involved in establishment of muscle stem cells through life, and acquisition of muscle stem cell properties. We have identified multiple genes and pathways associated with satellite cell formation, including set of genes specifically induced (EphA1, EphA2, EfnA1, EphB1, Zbtb4, Zbtb20) or inhibited (EphA3, EphA4, EphA7, EfnA2, EfnA3, EfnA4, EfnA5, EphB2, EphB3, EphB4, EfnBs, Zfp354c, Zcchc5, Hmga2) in adult stem cells. Ephrin receptors and ephrins ligands have been implicated in cell migration and guidance in many tissues including skeletal muscle. Here we show that Ephrin receptors and ephrins ligands are also involved in regulating the adult myogenic program. Strikingly, impairment of EPHB1 function in satellite cells leads to increased differentiation at the expense of self-renewal in isolated myofiber cultures. In addition, we identified new transcription factors, including several zinc finger proteins. ZFP354C and ZCCHC5 decreased self-renewal capacity when overexpressed, whereas ZBTB4 increased it, and ZBTB20 induced myogenic progression. The architectural and transcriptional regulator HMGA2 was involved in satellite cell activation. Together, our study shows that transcriptome profiling coupled with myofiber culture analysis, provides an efficient system to identify and validate candidate genes implicated in establishment/maintenance of muscle stem cells. Furthermore, tour de force transcriptomic profiling provides a wealth of data to inform for future stem cell-based muscle therapies. PMID:27446912

  2. Factors regulating stem cell recruitment to the fetal thymus.

    PubMed

    Wilkinson, B; Owen, J J; Jenkinson, E J

    1999-04-01

    Colonization of the thymic rudiment during development is initiated before vascularization so that hemopoietic precursors must leave the pharyngeal vessels and migrate through the perithymic mesenchyme to reach the thymus, suggesting that they may be responding to a gradient of chemoattractant factors. We report that diffusible chemoattractants are produced by MHC class II+ epithelial cells of the fetal thymus, and that the response of precursors to these factors is mediated via a G protein-coupled receptor, consistent with factors being members of the chemokine family. Indeed, a number of chemokine receptors are expressed by thymic precursors, and several chemokines are also expressed by thymic epithelial cells. However, these chemokines are also expressed in a tissue that is unable to attract precursors, although the thymus expressed chemokine, TECK, is expressed at higher levels in thymic epithelial cells and we show that it has chemotactic activity for isolated thymic precursors. Neutralizing Ab to TECK, however, did not prevent thymus recolonization by T cell precursors, suggesting that other novel chemokines might be involved in this process. In addition, we provide evidence for the involvement of matrix metalloproteinases in chemoattractant-mediated T cell precursor recruitment to the thymus during embryogenesis.

  3. Actinomycin D Down-regulates SOX2 Expression and Induces Death in Breast Cancer Stem Cells.

    PubMed

    Das, Tuhin; Nair, Rajesh R; Green, Ryan; Padhee, Shruti; Howell, Mark; Banerjee, Jit; Mohapatra, Shyam S; Mohapatra, Subhra

    2017-04-01

    One of the major hurdles in the treatment of breast cancers is the inability of anti-cancer drugs to eliminate the breast cancer stem cells (BCSCs) population, which leads to disease relapse. The dearth in anti-cancer drugs that target BCSCs can be attributed to the absence of in vitro screening models that can not only recapitulate the tumor microenvironment consisting of BCSCs but also preserve the 3-dimensional (3D) architecture of in vivo tumors. In our present study, we have developed a 3D cell culture system that shows: (i) enrichment of BCSCs, (ii) increased drug resistance, and (iii) generation of hypoxic conditions similar to tumors. Using this model, we were able to screen a FDA-approved diversity set and identify as well as validate actinomycin D as a potential anti-breast cancer agent. Interestingly, we show that actinomycin D specifically targets and down-regulates the expression of the stem cell transcription factor, Sox-2. Additionally, down-regulation of Sox-2 leads to depletion of the stem-cell population resulting in the inability of breast cancer cells to initiate tumor progression. This study demonstrates the utility of an in vivo-like 3D cell culture system for the identification and validation of anti-cancer agents that will have a better probability of success in the clinic. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  4. Regulation of osteogenic differentiation of human adipose-derived stem cells by controlling electromagnetic field conditions

    PubMed Central

    Kang, Kyung Shin; Hong, Jung Min; Kang, Jo A; Rhie, Jong-Won; Jeong, Young Hun; Cho, Dong-Woo

    2013-01-01

    Many studies have reported that an electromagnetic field can promote osteogenic differentiation of mesenchymal stem cells. However, experimental results have differed depending on the experimental and environmental conditions. Optimization of electromagnetic field conditions in a single, identified system can compensate for these differences. Here we demonstrated that specific electromagnetic field conditions (that is, frequency and magnetic flux density) significantly regulate osteogenic differentiation of adipose-derived stem cells (ASCs) in vitro. Before inducing osteogenic differentiation, we determined ASC stemness and confirmed that the electromagnetic field was uniform at the solenoid coil center. Then, we selected positive (30/45 Hz, 1 mT) and negative (7.5 Hz, 1 mT) osteogenic differentiation conditions by quantifying alkaline phosphate (ALP) mRNA expression. Osteogenic marker (for example, runt-related transcription factor 2) expression was higher in the 30/45 Hz condition and lower in the 7.5 Hz condition as compared with the nonstimulated group. Both positive and negative regulation of ALP activity and mineralized nodule formation supported these responses. Our data indicate that the effects of the electromagnetic fields on osteogenic differentiation differ depending on the electromagnetic field conditions. This study provides a framework for future work on controlling stem cell differentiation. PMID:23306704

  5. B-cell receptor-associated protein 31 regulates human embryonic stem cell adhesion, stemness, and survival via control of epithelial cell adhesion molecule.

    PubMed

    Kim, Won-Tae; Seo Choi, Hong; Min Lee, Hyun; Jang, Young-Joo; Ryu, Chun Jeih

    2014-10-01

    B-Cell receptor-associated protein 31 (BAP31) regulates the export of secreted membrane proteins from the endoplasmic reticulum (ER) to the downstream secretory pathway. Previously, we generated a monoclonal antibody 297-D4 against the surface molecule on undifferentiated human embryonic stem cells (hESCs). Here, we found that 297-D4 antigen was localized to pluripotent hESCs and downregulated during early differentiation of hESCs and identified that the antigen target of 297-D4 was BAP31 on the hESC-surface. To investigate the functional role of BAP31 in hESCs, BAP31 expression was knocked down by small interfering RNA. BAP31 depletion impaired hESC self-renewal and pluripotency and drove hESC differentiation into multicell lineages. BAP31 depletion hindered hESC proliferation by arresting cell cycle at G0/G1 phase and inducing caspase-independent cell death. Interestingly, BAP31 depletion reduced hESC adhesion to extracellular matrix (ECM). Analysis of cell surface molecules showed decreased expression of epithelial cell adhesion molecule (EpCAM) in BAP31-depleted hESCs, while ectopic expression of BAP31 elevated the expression of EpCAM. EpCAM depletion also reduced hESC adhesion to ECM, arrested cell cycle at G0/G1 phase and induced cell death, producing similar effects to those of BAP31 depletion. BAP31 and EpCAM were physically associated and colocalized at the ER and cell surface. Both BAP31 and EpCAM depletion decreased cyclin D1 and E expression and suppressed PI3K/Akt signaling, suggesting that BAP31 regulates hESC stemness and survival via control of EpCAM expression. These findings provide, for the first time, mechanistic insights into how BAP31 regulates hESC stemness and survival via control of EpCAM expression.

  6. Regulation of KAT6 Acetyltransferases and Their Roles in Cell Cycle Progression, Stem Cell Maintenance, and Human Disease

    PubMed Central

    Huang, Fu

    2016-01-01

    The lysine acetyltransferase 6 (KAT6) histone acetyltransferase (HAT) complexes are highly conserved from yeast to higher organisms. They acetylate histone H3 and other nonhistone substrates and are involved in cell cycle regulation and stem cell maintenance. In addition, the human KAT6 HATs are recurrently mutated in leukemia and solid tumors. Therefore, it is important to understand the mechanisms underlying the regulation of KAT6 HATs and their roles in cell cycle progression. In this minireview, we summarize the identification and analysis of the KAT6 complexes and discuss the regulatory mechanisms governing their enzymatic activities and substrate specificities. We further focus on the roles of KAT6 HATs in regulating cell proliferation and stem cell maintenance and review recent insights that aid in understanding their involvement in human diseases. PMID:27185879

  7. Regulation of KAT6 Acetyltransferases and Their Roles in Cell Cycle Progression, Stem Cell Maintenance, and Human Disease.

    PubMed

    Huang, Fu; Abmayr, Susan M; Workman, Jerry L

    2016-07-15

    The lysine acetyltransferase 6 (KAT6) histone acetyltransferase (HAT) complexes are highly conserved from yeast to higher organisms. They acetylate histone H3 and other nonhistone substrates and are involved in cell cycle regulation and stem cell maintenance. In addition, the human KAT6 HATs are recurrently mutated in leukemia and solid tumors. Therefore, it is important to understand the mechanisms underlying the regulation of KAT6 HATs and their roles in cell cycle progression. In this minireview, we summarize the identification and analysis of the KAT6 complexes and discuss the regulatory mechanisms governing their enzymatic activities and substrate specificities. We further focus on the roles of KAT6 HATs in regulating cell proliferation and stem cell maintenance and review recent insights that aid in understanding their involvement in human diseases. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  8. Eye Absence Does Not Regulate Planarian Stem Cells during Eye Regeneration.

    PubMed

    LoCascio, Samuel A; Lapan, Sylvain W; Reddien, Peter W

    2017-02-27

    Dividing cells called neoblasts contain pluripotent stem cells and drive planarian flatworm regeneration from diverse injuries. A long-standing question is whether neoblasts directly sense and respond to the identity of missing tissues during regeneration. We used the eye to investigate this question. Surprisingly, eye removal was neither sufficient nor necessary for neoblasts to increase eye progenitor production. Neoblasts normally increase eye progenitor production following decapitation, facilitating regeneration. Eye removal alone, however, did not induce this response. Eye regeneration following eye-specific resection resulted from homeostatic rates of eye progenitor production and less cell death in the regenerating eye. Conversely, large head injuries that left eyes intact increased eye progenitor production. Large injuries also non-specifically increased progenitor production for multiple uninjured tissues. We propose a model for eye regeneration in which eye tissue production by planarian stem cells is not directly regulated by the absence of the eye itself. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Regulation of miRNAs Affects Radiobiological Response of Lung Cancer Stem Cells

    PubMed Central

    Xu, Yan-mei; Liao, Xing-yun; Chen, Xie-wan; Li, De-zhi; Sun, Jian-guo; Liao, Rong-xia

    2015-01-01

    Radiotherapy (RT) is a key therapeutic strategy for lung cancer, the most common cause of cancer-related deaths worldwide, but radioresistance often occurs and leads to failure of RT. It is therefore important to clarify the mechanism underlying radioresistance in lung cancer. Cancer stem cells (CSCs) are considered the fundamental reason for radioresistance. MicroRNAs (miRNAs) have been regarded as important regulatory molecules of CSCs, carcinogenesis, and treatment response of cancers. It is crucial to clarify how regulation of miRNAs affects repair of DNA damage, redistribution, repopulation, reoxygenation, and radiosensitivity (5R) of lung cancer stem cells (LCSCs). A thorough understanding of the regulation of miRNAs affecting 5R of LCSCs has potential impact on identifying novel targets and thus may improve the efficacy of lung cancer radiotherapy. PMID:25815339

  10. The Role of miRNAs in the Regulation of Pancreatic Cancer Stem Cells

    PubMed Central

    Bimonte, Sabrina; Barbieri, Antonio; Leongito, Maddalena; Palma, Giuseppe; del Vecchio, Vitale; Falco, Michela; Palaia, Raffaele; Albino, Vittorio; Piccirillo, Mauro; Amore, Alfonso; Petrillo, Antonella; Granata, Vincenza; Izzo, Francesco

    2016-01-01

    Pancreatic ductal adenocarcinoma is currently one of the deadliest cancers with low overall survival rate. This disease leads to an aggressive local invasion and early metastases and is poorly responsive to treatment with chemotherapy or chemoradiotherapy. Several studies have shown that pancreatic cancer stem cells (PCSCs) play different roles in the regulation of drug resistance and recurrence in pancreatic cancer. MicroRNA (miRNA), a class of newly emerging small noncoding RNAs, is involved in the modulation of several biological activities ranging from invasion to metastases development, as well as drug resistance of pancreatic cancer. In this review, we synthesize the latest findings on the role of miRNAs in regulating different biological properties of pancreatic cancer stem cells. PMID:27006664

  11. Cytokines regulate postnatal hematopoietic stem cell expansion: opposing roles of thrombopoietin and LNK

    PubMed Central

    Buza-Vidas, Natalija; Antonchuk, Jennifer; Qian, Hong; Månsson, Robert; Luc, Sidinh; Zandi, Sasan; Anderson, Kristina; Takaki, Satoshi; Nygren, Jens M.; Jensen, Christina T.; Jacobsen, Sten Eirik W.

    2006-01-01

    The role of cytokines as regulators of hematopoietic stem cell (HSC) expansion remains elusive. Herein, we identify thrombopoietin (THPO) and the cytokine signaling inhibitor LNK, as opposing physiological regulators of HSC expansion. Lnk−/− HSCs continue to expand postnatally, up to 24-fold above normal by 6 mo of age. Within the stem cell compartment, this expansion is highly selective for self-renewing long-term HSCs (LT-HSCs), which show enhanced THPO responsiveness. Lnk−/− HSC expansion is dependent on THPO, and 12-wk-old Lnk−/−Thpo−/− mice have 65-fold fewer LT-HSCs than Lnk−/− mice. Expansions of multiple myeloid, but not lymphoid, progenitors in Lnk−/− mice also proved THPO-dependent. PMID:16882979

  12. Hematopoietic stem and progenitor cells regulate the regeneration of their niche by secreting Angiopoietin-1

    PubMed Central

    Zhou, Bo O; Ding, Lei; Morrison, Sean J

    2015-01-01

    Hematopoietic stem cells (HSCs) are maintained by a perivascular niche in bone marrow but it is unclear whether the niche is reciprocally regulated by HSCs. Here, we systematically assessed the expression and function of Angiopoietin-1 (Angpt1) in bone marrow. Angpt1 was not expressed by osteoblasts. Angpt1 was most highly expressed by HSCs, and at lower levels by c-kit+ hematopoietic progenitors, megakaryocytes, and Leptin Receptor+ (LepR+) stromal cells. Global conditional deletion of Angpt1, or deletion from osteoblasts, LepR+ cells, Nes-cre-expressing cells, megakaryocytes, endothelial cells or hematopoietic cells in normal mice did not affect hematopoiesis, HSC maintenance, or HSC quiescence. Deletion of Angpt1 from hematopoietic cells and LepR+ cells had little effect on vasculature or HSC frequency under steady-state conditions but accelerated vascular and hematopoietic recovery after irradiation while increasing vascular leakiness. Hematopoietic stem/progenitor cells and LepR+ stromal cells regulate niche regeneration by secreting Angpt1, reducing vascular leakiness but slowing niche recovery. DOI: http://dx.doi.org/10.7554/eLife.05521.001 PMID:25821987

  13. Regulation of Breast Cancer Stem Cell by Tissue Rigidity

    DTIC Science & Technology

    2015-06-01

    down Twist1 prevented loosing of adherent junctions as evident by E-cadherin (green) membrane localization. 6 EMT-inducing transcription factors...Snail2, prevented the EMT-like invasive phenotype induced by the stiff matrix stiffness of 5700Pa; instead these mammary cells formed spheroid mammary...RNAs (shRNAs) against TWIST1 and tested their mechanosensing competence (Fig. 1b and Supplementary Fig. 1B–D). Knockdown of TWIST1 prevented the

  14. Implant Surface Design Regulates Mesenchymal Stem Cell Differentiation and Maturation.

    PubMed

    Boyan, B D; Cheng, A; Olivares-Navarrete, R; Schwartz, Z

    2016-03-01

    Changes in dental implant materials, structural design, and surface properties can all affect biological response. While bulk properties are important for mechanical stability of the implant, surface design ultimately contributes to osseointegration. This article reviews the surface parameters of dental implant materials that contribute to improved cell response and osseointegration. In particular, we focus on how surface design affects mesenchymal cell response and differentiation into the osteoblast lineage. Surface roughness has been largely studied at the microscale, but recent studies have highlighted the importance of hierarchical micron/submicron/nanosurface roughness, as well as surface roughness in combination with surface wettability. Integrins are transmembrane receptors that recognize changes in the surface and mediate downstream signaling pathways. Specifically, the noncanonical Wnt5a pathway has been implicated in osteoblastic differentiation of cells on titanium implant surfaces. However, much remains to be elucidated. Only recently have studies been conducted on the differences in biological response to implants based on sex, age, and clinical factors; these all point toward differences that advocate for patient-specific implant design. Finally, challenges in implant surface characterization must be addressed to optimize and compare data across studies. An understanding of both the science and the biology of the materials is crucial for developing novel dental implant materials and surface modifications for improved osseointegration. © International & American Associations for Dental Research 2016.

  15. Implant Surface Design Regulates Mesenchymal Stem Cell Differentiation and Maturation

    PubMed Central

    Boyan, B.D.; Cheng, A.; Olivares-Navarrete, R.; Schwartz, Z.

    2016-01-01

    Changes in dental implant materials, structural design, and surface properties can all affect biological response. While bulk properties are important for mechanical stability of the implant, surface design ultimately contributes to osseointegration. This article reviews the surface parameters of dental implant materials that contribute to improved cell response and osseointegration. In particular, we focus on how surface design affects mesenchymal cell response and differentiation into the osteoblast lineage. Surface roughness has been largely studied at the microscale, but recent studies have highlighted the importance of hierarchical micron/submicron/nanosurface roughness, as well as surface roughness in combination with surface wettability. Integrins are transmembrane receptors that recognize changes in the surface and mediate downstream signaling pathways. Specifically, the noncanonical Wnt5a pathway has been implicated in osteoblastic differentiation of cells on titanium implant surfaces. However, much remains to be elucidated. Only recently have studies been conducted on the differences in biological response to implants based on sex, age, and clinical factors; these all point toward differences that advocate for patient-specific implant design. Finally, challenges in implant surface characterization must be addressed to optimize and compare data across studies. An understanding of both the science and the biology of the materials is crucial for developing novel dental implant materials and surface modifications for improved osseointegration. PMID:26927483

  16. STAT3 is a key transcriptional regulator of cancer stem cell marker CD133 in HCC

    PubMed Central

    Ghoshal, Sarani; Fuchs, Bryan C.

    2016-01-01

    Cancer stem cell (CSC) marker CD133 was found to be upregulated in many cancers including hepatocellular carcinoma (HCC). However, the molecular mechanism of CD133 regulation in the liver tumor microenvironment has remained elusive. In this study Won and colleagues report that interleukin-6 (IL-6) mediated signal transducer and activator of transcription factor 3 (STAT3) signaling and hypoxia enhance the expression of CD133 and promote the progression of HCC. PMID:27275460

  17. SCL/TAL1 Regulates Hematopoietic Specification From Human Embryonic Stem Cells

    PubMed Central

    Real, Pedro J; Ligero, Gertrudis; Ayllon, Veronica; Ramos-Mejia, Veronica; Bueno, Clara; Gutierrez-Aranda, Ivan; Navarro-Montero, Oscar; Lako, Majlinda; Menendez, Pablo

    2012-01-01

    Determining the molecular regulators/pathways responsible for the specification of human embryonic stem cells (hESCs) into hematopoietic precursors has far-reaching implications for potential cell therapies and disease modeling. Mouse models lacking SCL/TAL1 (stem cell leukemia/T-cell acute lymphocytic leukemia 1) do not survive beyond early embryogenesis because of complete absence of hematopoiesis, indicating that SCL is a master early hematopoietic regulator. SCL is commonly found rearranged in human leukemias. However, there is barely information on the role of SCL on human embryonic hematopoietic development. Differentiation and sorting assays show that endogenous SCL expression parallels hematopoietic specification of hESCs and that SCL is specifically expressed in hematoendothelial progenitors (CD45−CD31+CD34+) and, to a lesser extent, on CD45+ hematopoietic cells. Enforced expression of SCL in hESCs accelerates the emergence of hematoendothelial progenitors and robustly promotes subsequent differentiation into primitive (CD34+CD45+) and total (CD45+) blood cells with higher clonogenic potential. Short-hairpin RNA–based silencing of endogenous SCL abrogates hematopoietic specification of hESCs, confirming the early hematopoiesis-promoting effect of SCL. Unfortunately, SCL expression on its own is not sufficient to confer in vivo engraftment to hESC-derived hematopoietic cells, suggesting that additional yet undefined master regulators are required to orchestrate the stepwise hematopoietic developmental process leading to the generation of definitive in vivo functional hematopoiesis from hESCs. PMID:22491213

  18. MicroRNA regulation of adipose derived stem cells in aging rats.

    PubMed

    Fei, Jia; Tamski, Holly; Cook, Carla; Santanam, Nalini

    2013-01-01

    Perturbations in abdominal fat secreted adipokines play a key role in metabolic syndrome. This process is further altered during the aging process, probably due to alterations in the preadipocytes (aka. stromal vascular fraction cells-SVF cells or adipose derived stem cells-ASCs) composition and/or function. Since microRNAs regulate genes involved both in development and aging processes, we hypothesized that the impaired adipose function with aging is due to altered microRNA regulation of adipogenic pathways in SVF cells. Alterations in mRNA and proteins associated with adipogenic differentiation (ERK5 and PPARg) but not osteogenic (RUNX2) pathways were observed in SVF cells isolated from visceral adipose tissue with aging (6 to 30 mo) in female Fischer 344 x Brown Norway Hybrid (FBN) rats. The impaired differentiation capacity with aging correlated with altered levels of miRNAs involved in adipocyte differentiation (miRNA-143) and osteogenic pathways (miRNA-204). Gain and loss of function studies using premir or antagomir-143 validated the age associated adipocyte dysfunction. Our studies for the first time indicate a role for miRNA mediated regulation of SVF cells with aging. This discovery is important in the light of the findings that dysfunctional adipose derived stem cells contribute to age related chronic diseases.

  19. Effects of p21 Gene Down-Regulation through RNAi on Antler Stem Cells In Vitro

    PubMed Central

    Guo, Qianqian; Wang, Datao; Liu, Zhen; Li, Chunyi

    2015-01-01

    Cell cycle is an integral part of cell proliferation, and consists mainly of four phases, G1, S, G2 and M. The p21 protein, a cyclin dependent kinase inhibitor, plays a key role in regulating cell cyclevia G1 phase control. Cells capable of epimorphic regeneration have G2/M accumulation as their distinctive feature, whilst the majority of somatic cells rest at G1 phase. To investigate the role played byp21 in antler regeneration, we studied the cell cycle distribution of antler stem cells (ASCs), via down-regulation of p21 in vitro using RNAi. The results showed that ASCs had high levels of p21 mRNA expression and rested at G1 phase, which was comparable to the control somatic cells. Down-regulation of p21 did not result in ASC cell cycle re-distribution toward G2/M accumulation, but DNA damage and apoptosis of the ASCs significantly increased and the process of cell aging was slowed. These findings suggest that the ASCs may have evolved to use an alternative, p21-independent cell cycle regulation mechanism. Also a unique p21-dependent inhibitory effect may control DNA damage as a protective mechanism to ensure the fast proliferating ASCs do not become dysplastic/cancerous. Understanding of the mechanism underlying the role played by p21 in the ASCs could give insight into a mammalian system where epimorphic regeneration is initiated whilst the genome stability is effectively maintained. PMID:26308075

  20. Regulation of stem cell therapies under attack in Europe: for whom the bell tolls.

    PubMed

    Bianco, Paolo; Barker, Roger; Brüstle, Oliver; Cattaneo, Elena; Clevers, Hans; Daley, George Q; De Luca, Michele; Goldstein, Lawrence; Lindvall, Olle; Mummery, Christine; Robey, Pamela G; Sattler de Sousa E Brito, Clara; Smith, Austin

    2013-05-29

    At the time of writing, the Italian Parliament is debating a new law that would make it legal to practice an unproven stem cell treatment in public hospitals. The treatment, offered by a private non-medical organization, may not be safe, lacks a rationale, and violates current national laws and European regulations. This case raises multiple concerns, most prominently the urgent need to protect patients who are severely ill, exposed to significant risks, and vulnerable to exploitation. The scientific community must consider the context-social, financial, medical, legal-in which stem cell science is currently situated and the need for stringent regulation. Additional concerns are emerging. These emanate from the novel climate, created within science itself, and stem cell science in particular, by the currently prevailing model of 'translational medicine'. Only rigorous science and rigorous regulation can ensure translation of science into effective therapies rather than into ineffective market products, and mark, at the same time, the sharp distinction between the striving for new therapies and the deceit of patients.

  1. Expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells regulates proliferation, differentiation, and maintenance of hematopoietic stem and progenitor cells

    PubMed Central

    Stopp, Sabine; Bornhäuser, Martin; Ugarte, Fernando; Wobus, Manja; Kuhn, Matthias; Brenner, Sebastian; Thieme, Sebastian

    2013-01-01

    The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact. PMID:22801967

  2. Expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells regulates proliferation, differentiation, and maintenance of hematopoietic stem and progenitor cells.

    PubMed

    Stopp, Sabine; Bornhäuser, Martin; Ugarte, Fernando; Wobus, Manja; Kuhn, Matthias; Brenner, Sebastian; Thieme, Sebastian

    2013-04-01

    The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact.

  3. Hedgehog controls neural stem cells through p53-independent regulation of Nanog

    PubMed Central

    Po, Agnese; Ferretti, Elisabetta; Miele, Evelina; De Smaele, Enrico; Paganelli, Arianna; Canettieri, Gianluca; Coni, Sonia; Di Marcotullio, Lucia; Biffoni, Mauro; Massimi, Luca; Di Rocco, Concezio; Screpanti, Isabella; Gulino, Alberto

    2010-01-01

    Hedgehog (Hh) pathway has a pivotal function in development and tumorigenesis, processes sustained by stem cells (SCs). The transcription factor Nanog controls stemness acting as a key determinant of both embryonic SC self-renewal and differentiated somatic cells reprogramming to pluripotency, in concert with the loss of the oncosuppressor p53. How Nanog is regulated by microenvironmental signals in postnatal SC niches has been poorly investigated. Here, we show that Nanog is highly expressed in SCs from postnatal cerebellum and medulloblastoma, and acts as a critical mediator of Hh-driven self-renewal. Indeed, the downstream effectors of Hh activity, Gli1 and Gli2, bind to Nanog-specific cis-regulatory sequences both in mouse and human SCs. Loss of p53, a key event promoting cell stemness, activates Hh signalling, thereby contributing to Nanog upregulation. Conversely, Hh downregulates p53 but does not require p53 to control Nanog. Our data reveal a mechanism for the function of Hh in the control of stemness that represents a crucial component of an integrated circuitry determining cell fate decision and involved in the maintenance of cancer SCs. PMID:20581804

  4. Pharmacological Regulation of In Situ Tissue Stem Cells Differentiation for Soft Tissue Calcification Treatment.

    PubMed

    Hu, Jia-Jie; Yin, Zi; Shen, Wei-Liang; Xie, Yu-Bin; Zhu, Ting; Lu, Ping; Cai, You-Zhi; Kong, Min-Jian; Heng, Boon Chin; Zhou, Yi-Ting; Chen, Wei-Shan; Chen, Xiao; Ouyang, Hong-Wei

    2016-04-01

    Calcification of soft tissues, such as heart valves and tendons, is a common clinical problem with limited therapeutics. Tissue specific stem/progenitor cells proliferate to repopulate injured tissues. But some of them become divergent to the direction of ossification in the local pathological microenvironment, thereby representing a cellular target for pharmacological approach. We observed that HIF-2alpha (encoded by EPAS1 inclined form) signaling is markedly activated within stem/progenitor cells recruited at calcified sites of diseased human tendons and heart valves. Proinflammatory microenvironment, rather than hypoxia, is correlated with HIF-2alpha activation and promoted osteochondrogenic differentiation of tendon stem/progenitor cells (TSPCs). Abnormal upregulation of HIF-2alpha served as a key switch to direct TSPCs differentiation into osteochondral-lineage rather than teno-lineage. Notably, Scleraxis (Scx), an essential tendon specific transcription factor, was suppressed on constitutive activation of HIF-2alpha and mediated the effect of HIF-2alpha on TSPCs fate decision. Moreover, pharmacological inhibition of HIF-2alpha with digoxin, which is a widely utilized drug, can efficiently inhibit calcification and enhance tenogenesis in vitro and in the Achilles's tendinopathy model. Taken together, these findings reveal the significant role of the tissue stem/progenitor cells fate decision and suggest that pharmacological regulation of HIF-2alpha function is a promising approach for soft tissue calcification treatment.

  5. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    SciTech Connect

    Joseph, Bertrand; Hermanson, Ola

    2010-05-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  6. Molecular control of brain size: regulators of neural stem cell life, death and beyond.

    PubMed

    Joseph, Bertrand; Hermanson, Ola

    2010-05-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or "pilots", to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events. Copyright 2010 Elsevier Inc. All rights reserved.

  7. E-cadherin regulates the behavior and fate of epithelial stem cells and their progeny in the mouse incisor

    PubMed Central

    Li, Chun-Ying; Cha, Wanghee; Luder, Hans-Ulrich; Charles, Roch-Philippe; McMahon, Martin; Mitsiadis, Thimios; Klein, Ophir D.

    2013-01-01

    Stem cells are essential for the regeneration and homeostasis of many organs, such as tooth, hair, skin, and intestine. Although human tooth regeneration is limited, a number of animals have evolved continuously growing teeth that provide models of stem cell-based organ renewal. A well-studied model is the mouse incisor, which contains dental epithelial stem cells in structures known as cervical loops. These stem cells produce progeny that proliferate and migrate along the proximo-distal axis of the incisor and differentiate into enamel-forming ameloblasts. Here, we studied the role of E-cadherin in behavior of the stem cells and their progeny. Levels of E-cadherin are highly dynamic in the incisor, such that E-cadherin is expressed in the stem cells, downregulated in the transit-amplifying cells, re-expressed in the pre-ameloblasts and then downregulated again in the ameloblasts. Conditional inactivation of E-cadherin in the cervical loop led to decreased numbers of label-retaining stem cells, increased proliferation, and decreased cell migration in the mouse incisor. Using both genetic and pharmacological approaches, we showed that Fibroblast Growth Factors regulate E-cadherin expression, cell proliferation and migration in the incisor. Together, our data indicate that E-cadherin is an important regulator of stem cells and their progeny during growth of the mouse incisor. PMID:22537490

  8. Comparing national home-keeping and the regulation of translational stem cell applications: An international perspective.

    PubMed

    Sleeboom-Faulkner, Margaret; Chekar, Choon Key; Faulkner, Alex; Heitmeyer, Carolyn; Marouda, Marina; Rosemann, Achim; Chaisinthop, Nattaka; Chang, Hung-Chieh Jessica; Ely, Adrian; Kato, Masae; Patra, Prasanna K; Su, Yeyang; Sui, Suli; Suzuki, Wakana; Zhang, Xinqing

    2016-03-01

    A very large grey area exists between translational stem cell research and applications that comply with the ideals of randomised control trials and good laboratory and clinical practice and what is often referred to as snake-oil trade. We identify a discrepancy between international research and ethics regulation and the ways in which regulatory instruments in the stem cell field are developed in practice. We examine this discrepancy using the notion of 'national home-keeping', referring to the way governments articulate international standards and regulation with conflicting demands on local players at home. Identifying particular dimensions of regulatory tools - authority, permissions, space and acceleration - as crucial to national home-keeping in Asia, Europe and the USA, we show how local regulation works to enable development of the field, notwithstanding international (i.e. principally 'western') regulation. Triangulating regulation with empirical data and archival research between 2012 and 2015 has helped us to shed light on how countries and organisations adapt and resist internationally dominant regulation through the manipulation of regulatory tools (contingent upon country size, the state's ability to accumulate resources, healthcare demands, established traditions of scientific governance, and economic and scientific ambitions). Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Regulation of CTNNB1 signaling in gastric cancer and stem cells

    PubMed Central

    Tanabe, Shihori; Aoyagi, Kazuhiko; Yokozaki, Hiroshi; Sasaki, Hiroki

    2016-01-01

    Recent research has shown that the alteration of combinations in gene expression contributes to cellular phenotypic changes. Previously, it has been demonstrated that the combination of cadherin 1 and cadherin 2 expression can identify the diffuse-type and intestinal-type gastric cancers. Although the diffuse-type gastric cancer has been resistant to treatment, the precise mechanism and phenotypic involvement has not been revealed. It may be possible that stem cells transform into gastric cancer cells, possibly through the involvement of a molecule alteration and signaling mechanism. In this review article, we focus on the role of catenin beta 1 (CTNNB1 or β-catenin) and describe the regulation of CTNNB1 signaling in gastric cancer and stem cells. PMID:27574551

  10. Hematopoietic stem cell fate decisions are regulated by Wnt antagonists: comparisons and current controversies.

    PubMed

    Cain, Corey J; Manilay, Jennifer O

    2013-01-01

    Wingless and int (Wnt) proteins are secreted proteins that are important for regulating hematopoietic stem cell self-renewal and differentiation in the bone marrow microenvironment in mice. The mechanisms by which Wnt signaling regulates these hematopoietic cell fate decisions are not fully understood. Secreted Wnt antagonists, which are expressed in bone and bone marrow stromal cells, either bind to Wnt ligands directly or block Wnt receptors and co-receptors to halt Wnt-mediated signal transduction in both osteolineage and hematopoietic cell types. Secreted frizzled related proteins-1 and -2, Wnt inhibitory factor-1, Dickkopf-1, and Sclerostin are Wnt antagonists that influence hematopoietic cell fate decisions in the bone marrow niche. In this review, we compare and contrast the roles of these Wnt antagonists and their effects on hematopoietic development in mice, and also discuss the clinical significance of targeting Wnt antagonists within the context of hematopoietic disease.

  11. TCPs, WUSs, and WINDs: families of transcription factors that regulate shoot meristem formation, stem cell maintenance, and somatic cell differentiation.

    PubMed

    Ikeda, Miho; Ohme-Takagi, Masaru

    2014-01-01

    In contrast to somatic mammalian cells, which cannot alter their fate, plant cells can dedifferentiate to form totipotent callus cells and regenerate a whole plant, following treatment with specific phytohormones. However, the regulatory mechanisms and key factors that control differentiation-dedifferentiation and cell totipotency have not been completely clarified in plants. Recently, several plant transcription factors that regulate meristem formation and dedifferentiation have been identified and include members of the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP), WUSCHEL (WUS), and WOUND INDUCED DEDIFFERENTIATION (WIND1) families. WUS and WIND positively control plant cell totipotency, while TCP negatively controls it. Interestingly, TCP is a transcriptional activator that acts as a negative regulator of shoot meristem formation, and WUS is a transcriptional repressor that positively maintains totipotency of the stem cells of the shoot meristem. We describe here the functions of TCP, WUS, and WIND transcription factors in the regulation of differentiation-dedifferentiation by positive and negative transcriptional regulators.

  12. BLOS2 negatively regulates Notch signaling during neural and hematopoietic stem and progenitor cell development

    PubMed Central

    Zhou, Wenwen; He, Qiuping; Zhang, Chunxia; He, Xin; Cui, Zongbin; Liu, Feng; Li, Wei

    2016-01-01

    Notch signaling plays a crucial role in controling the proliferation and differentiation of stem and progenitor cells during embryogenesis or organogenesis, but its regulation is incompletely understood. BLOS2, encoded by the Bloc1s2 gene, is a shared subunit of two lysosomal trafficking complexes, biogenesis of lysosome-related organelles complex-1 (BLOC-1) and BLOC-1-related complex (BORC). Bloc1s2−/− mice were embryonic lethal and exhibited defects in cortical development and hematopoiesis. Loss of BLOS2 resulted in elevated Notch signaling, which consequently increased the proliferation of neural progenitor cells and inhibited neuronal differentiation in cortices. Likewise, ablation of bloc1s2 in zebrafish or mice led to increased hematopoietic stem and progenitor cell production in the aorta-gonad-mesonephros region. BLOS2 physically interacted with Notch1 in endo-lysosomal trafficking of Notch1. Our findings suggest that BLOS2 is a novel negative player in regulating Notch signaling through lysosomal trafficking to control multiple stem and progenitor cell homeostasis in vertebrates. DOI: http://dx.doi.org/10.7554/eLife.18108.001 PMID:27719760

  13. Role of nitric oxide in the maintenance of pluripotency and regulation of the hypoxia response in stem cells

    PubMed Central

    Beltran-Povea, Amparo; Caballano-Infantes, Estefania; Salguero-Aranda, Carmen; Martín, Franz; Soria, Bernat; Bedoya, Francisco J; Tejedo, Juan R; Cahuana, Gladys M

    2015-01-01

    Stem cell pluripotency and differentiation are global processes regulated by several pathways that have been studied intensively over recent years. Nitric oxide (NO) is an important molecule that affects gene expression at the level of transcription and translation and regulates cell survival and proliferation in diverse cell types. In embryonic stem cells NO has a dual role, controlling differentiation and survival, but the molecular mechanisms by which it modulates these functions are not completely defined. NO is a physiological regulator of cell respiration through the inhibition of cytochrome c oxidase. Many researchers have been examining the role that NO plays in other aspects of metabolism such as the cellular bioenergetics state, the hypoxia response and the relationship of these areas to stem cell stemness. PMID:25914767

  14. Role of nitric oxide in the maintenance of pluripotency and regulation of the hypoxia response in stem cells.

    PubMed

    Beltran-Povea, Amparo; Caballano-Infantes, Estefania; Salguero-Aranda, Carmen; Martín, Franz; Soria, Bernat; Bedoya, Francisco J; Tejedo, Juan R; Cahuana, Gladys M

    2015-04-26

    Stem cell pluripotency and differentiation are global processes regulated by several pathways that have been studied intensively over recent years. Nitric oxide (NO) is an important molecule that affects gene expression at the level of transcription and translation and regulates cell survival and proliferation in diverse cell types. In embryonic stem cells NO has a dual role, controlling differentiation and survival, but the molecular mechanisms by which it modulates these functions are not completely defined. NO is a physiological regulator of cell respiration through the inhibition of cytochrome c oxidase. Many researchers have been examining the role that NO plays in other aspects of metabolism such as the cellular bioenergetics state, the hypoxia response and the relationship of these areas to stem cell stemness.

  15. Glycosyltransferase ST6GAL1 contributes to the regulation of pluripotency in human pluripotent stem cells.

    PubMed

    Wang, Yu-Chieh; Stein, Jason W; Lynch, Candace L; Tran, Ha T; Lee, Chia-Yao; Coleman, Ronald; Hatch, Adam; Antontsev, Victor G; Chy, Hun S; O'Brien, Carmel M; Murthy, Shashi K; Laslett, Andrew L; Peterson, Suzanne E; Loring, Jeanne F

    2015-08-25

    Many studies have suggested the significance of glycosyltransferase-mediated macromolecule glycosylation in the regulation of pluripotent states in human pluripotent stem cells (hPSCs). Here, we observed that the sialyltransferase ST6GAL1 was preferentially expressed in undifferentiated hPSCs compared to non-pluripotent cells. A lectin which preferentially recognizes α-2,6 sialylated galactosides showed strong binding reactivity with undifferentiated hPSCs and their glycoproteins, and did so to a much lesser extent with differentiated cells. In addition, downregulation of ST6GAL1 in undifferentiated hPSCs led to a decrease in POU5F1 (also known as OCT4) protein and significantly altered the expression of many genes that orchestrate cell morphogenesis during differentiation. The induction of cellular pluripotency in somatic cells was substantially impeded by the shRNA-mediated suppression of ST6GAL1, partially through interference with the expression of endogenous POU5F1 and SOX2. Targeting ST6GAL1 activity with a sialyltransferase inhibitor during cell reprogramming resulted in a dose-dependent reduction in the generation of human induced pluripotent stem cells (hiPSCs). Collectively, our data indicate that ST6GAL1 plays an important role in the regulation of pluripotency and differentiation in hPSCs, and the pluripotent state in human cells can be modulated using pharmacological tools to target sialyltransferase activity.

  16. Myc-regulated microRNAs attenuate embryonic stem cell differentiation

    PubMed Central

    Lin, Chin-Hsing; Jackson, Aimee L; Guo, Jie; Linsley, Peter S; Eisenman, Robert N

    2009-01-01

    Myc proteins are known to have an important function in stem cell maintenance. As Myc has been shown earlier to regulate microRNAs (miRNAs) involved in proliferation, we sought to determine whether c-Myc also affects embryonic stem (ES) cell maintenance and differentiation through miRNAs. Using a quantitative primer-extension PCR assay we identified miRNAs, including, miR-141, miR-200, and miR-429 whose expression is regulated by c-Myc in ES cells, but not in the differentiated and tumourigenic derivatives of ES cells. Chromatin immunoprecipitation analyses indicate that in ES cells c-Myc binds proximal to genomic regions encoding the induced miRNAs. We used expression profiling and seed homology to identify genes specifically downregulated both by these miRNAs and by c-Myc. We further show that the introduction of c-Myc-induced miRNAs into murine ES cells significantly attenuates the downregulation of pluripotency markers on induction of differentiation after withdrawal of the ES cell maintenance factor LIF. In contrast, knockdown of the endogenous miRNAs accelerate differentiation. Our data show that in ES cells c-Myc acts, in part, through a subset of miRNAs to attenuate differentiation. PMID:19745813

  17. Regulation of hematopoietic stem cell fate by the ubiquitin proteasome system

    PubMed Central

    Crusio, Kelly M.; Reavie, Linsey B.; Aifantis, Iannis

    2013-01-01

    Hematopoietic stem cells (HSCs) residing in the bone marrow generate mature blood cells throughout the life of the organism. This is accomplished by careful regulation of HSC activity to balance quiescence, self-renewal and differentiation. Studies of the molecular mechanisms governing HSC maintenance have mostly focused on the role of signaling and transcriptional processes. However, it has recently been demonstrated that protein regulation via the ubiquitin proteasome system (UPS) is crucial for normal HSC function. The loss of which can lead to transformation and leukemogenesis. The effective use of a general and reversible inhibitor of the UPS, Bortezomib, in treating mantle cell lymphoma and multiple myeloma demonstrated that targeting the UPS has therapeutic potential. Thus, understanding the emerging field of how the UPS regulates HSC activity may lead to novel targets for therapy of leukemia. PMID:22349458

  18. Miro1 regulates intercellular mitochondrial transport & enhances mesenchymal stem cell rescue efficacy

    PubMed Central

    Ahmad, Tanveer; Mukherjee, Shravani; Pattnaik, Bijay; Kumar, Manish; Singh, Suchita; Kumar, Manish; Rehman, Rakhshinda; Tiwari, Brijendra K; Jha, Kumar A; Barhanpurkar, Amruta P; Wani, Mohan R; Roy, Soumya S; Mabalirajan, Ulaganathan; Ghosh, Balaram; Agrawal, Anurag

    2014-01-01

    There is emerging evidence that stem cells can rejuvenate damaged cells by mitochondrial transfer. Earlier studies show that epithelial mitochondrial dysfunction is critical in asthma pathogenesis. Here we show for the first time that Miro1, a mitochondrial Rho-GTPase, regulates intercellular mitochondrial movement from mesenchymal stem cells (MSC) to epithelial cells (EC). We demonstrate that overexpression of Miro1 in MSC (MSCmiroHi) leads to enhanced mitochondrial transfer and rescue of epithelial injury, while Miro1 knockdown (MSCmiroLo) leads to loss of efficacy. Treatment with MSCmiroHi was associated with greater therapeutic efficacy, when compared to control MSC, in mouse models of rotenone (Rot) induced airway injury and allergic airway inflammation (AAI). Notably, airway hyperresponsiveness and remodeling were reversed by MSCmiroHi in three separate allergen-induced asthma models. In a human in vitro system, MSCmiroHi reversed mitochondrial dysfunction in bronchial epithelial cells treated with pro-inflammatory supernatant of IL-13-induced macrophages. Anti-inflammatory MSC products like NO, TGF-β, IL-10 and PGE2, were unchanged by Miro1 overexpression, excluding non-specific paracrine effects. In summary, Miro1 overexpression leads to increased stem cell repair. PMID:24431222

  19. TDIF peptide signaling regulates vascular stem cell proliferation via the WOX4 homeobox gene in Arabidopsis.

    PubMed

    Hirakawa, Yuki; Kondo, Yuki; Fukuda, Hiroo

    2010-08-01

    The indeterminate nature of plant growth and development depends on the stem cell system found in meristems. The Arabidopsis thaliana vascular meristem includes procambium and cambium. In these tissues, cell-cell signaling, mediated by a ligand-receptor pair made of the TDIF (for tracheary element differentiation inhibitory factor) peptide and the TDR/PXY (for TDIF RECEPTOR/ PHLOEM INTERCALATED WITH XYLEM) membrane protein kinase, promotes proliferation of procambial cells and suppresses their xylem differentiation. Here, we report that a WUSCHEL-related HOMEOBOX gene, WOX4, is a key target of the TDIF signaling pathway. WOX4 is expressed preferentially in the procambium and cambium, and its expression level was upregulated upon application of TDIF in a TDR-dependent manner. Genetic analyses showed that WOX4 is required for promoting the proliferation of procambial/cambial stem cells but not for repressing their commitment to xylem differentiation in response to the TDIF signal. Thus, at least two intracellular signaling pathways that diverge after TDIF recognition by TDR might regulate independently the behavior of vascular stem cells. Detailed observations in loss-of-function mutants revealed that TDIF-TDR-WOX4 signaling plays a crucial role in the maintenance of the vascular meristem organization during secondary growth.

  20. Lin28 is induced in primed embryonic stem cells and regulates let-7-independent events.

    PubMed

    Parisi, Silvia; Passaro, Fabiana; Russo, Luigi; Musto, Anna; Navarra, Angelica; Romano, Simona; Petrosino, Giuseppe; Russo, Tommaso

    2017-03-01

    Lin28 RNA-binding proteins play important roles in pluripotent stem cells, but the regulation of their expression and the mechanisms underlying their functions are still not definitively understood. Here we address the above-mentioned issues in the first steps of mouse embryonic stem cell (ESC) differentiation. We observed that the expression of Lin28 genes is transiently induced soon after the exit of ESCs from the naive ground state and that this induction is due to the Hmga2-dependent engagement of Otx2 with enhancers present at both Lin28 gene loci. These mechanisms are crucial for Lin28 regulation, as demonstrated by the abolishment of the Lin28 accumulation in Otx2- or Hmga2-knockout cells compared to the control cells. We have also found that Lin28 controls Hmga2 expression levels during ESC differentiation through a let-7-independent mechanism. Indeed, we found that Lin28 proteins bind a highly conserved element in the 3' UTR of Hmga2 mRNA, and this provokes a down-regulation of its translation. This mechanism prevents the inappropriate accumulation of Hmga2 that would modify the proliferation and physiological apoptosis of differentiating ESCs. In summary, we demonstrated that during ESC differentiation, Lin28 transient induction is dependent on Otx2 and Hmga2 and prevents an inappropriate excessive rise of Hmga2 levels.-Parisi, S., Passaro, F., Russo, L., Musto, A., Navarra, A., Romano, S., Petrosino, G., Russo, T. Lin28 is induced in primed embryonic stem cells and regulates let-7-independent events. © FASEB.

  1. Hedgehog Signaling Regulates Epithelial-Mesenchymal Transition in Pancreatic Cancer Stem-Like Cells

    PubMed Central

    Wang, Feng; Ma, Ling; Zhang, Zhengkui; Liu, Xiaoran; Gao, Hongqiao; Zhuang, Yan; Yang, Pei; Kornmann, Marko; Tian, Xiaodong; Yang, Yinmo

    2016-01-01

    Hedgehog (Hh) signaling is crucially involved in tumorigenesis. This study aimed to assess the role of Hh signaling in the regulation of epithelial-mesenchymal transition (EMT), stemness properties and chemoresistance of human pancreatic Panc-1 cancer stem cells (CSCs). Panc-1 cells were transfected with recombinant lentiviral vectors to silence SMO and serum-free floating-culture system was used to isolate Panc-1 tumorspheres. The expression of CSC and EMT markers was detected by flow cytometry, real-time RT-PCR and Western blot analysis. Malignant behaviors of Panc-1 CSC were evaluated by tumorigenicity assays and nude mouse lung metastasis model. We found that tumorspheres derived from pancreatic cancer cell line Panc-1 possessed self-renewal, differentiation and stemness properties. Hh pathway and EMT were active in Panc-1 tumorspheres. Inhibition of Hh signaling by SMO knockdown inhibited self-renewal, EMT, invasion, chemoresistance, pulmonary metastasis, tumorigenesis of pancreatic CSCs. In conclusion, Hh signaling contributes to the maintenance of stem-like properties and chemoresistance of pancreatic CSC and promotes the tumorigenesis and metastasis of pancreatic cancer. Hh pathway is a potential molecular target for the development of therapeutic strategies for pancreatic CSCs. PMID:26918054

  2. DNA context represents transcription regulation of the gene in mouse embryonic stem cells.

    PubMed

    Ha, Misook; Hong, Soondo

    2016-04-14

    Understanding gene regulatory information in DNA remains a significant challenge in biomedical research. This study presents a computational approach to infer gene regulatory programs from primary DNA sequences. Using DNA around transcription start sites as attributes, our model predicts gene regulation in the gene. We find that H3K27ac around TSS is an informative descriptor of the transcription program in mouse embryonic stem cells. We build a computational model inferring the cell-type-specific H3K27ac signatures in the DNA around TSS. A comparison of embryonic stem cell and liver cell-specific H3K27ac signatures in DNA shows that the H3K27ac signatures in DNA around TSS efficiently distinguish the cell-type specific H3K27ac peaks and the gene regulation. The arrangement of the H3K27ac signatures inferred from the DNA represents the transcription regulation of the gene in mESC. We show that the DNA around transcription start sites is associated with the gene regulatory program by specific interaction with H3K27ac.

  3. DNA context represents transcription regulation of the gene in mouse embryonic stem cells

    NASA Astrophysics Data System (ADS)

    Ha, Misook; Hong, Soondo

    2016-04-01

    Understanding gene regulatory information in DNA remains a significant challenge in biomedical research. This study presents a computational approach to infer gene regulatory programs from primary DNA sequences. Using DNA around transcription start sites as attributes, our model predicts gene regulation in the gene. We find that H3K27ac around TSS is an informative descriptor of the transcription program in mouse embryonic stem cells. We build a computational model inferring the cell-type-specific H3K27ac signatures in the DNA around TSS. A comparison of embryonic stem cell and liver cell-specific H3K27ac signatures in DNA shows that the H3K27ac signatures in DNA around TSS efficiently distinguish the cell-type specific H3K27ac peaks and the gene regulation. The arrangement of the H3K27ac signatures inferred from the DNA represents the transcription regulation of the gene in mESC. We show that the DNA around transcription start sites is associated with the gene regulatory program by specific interaction with H3K27ac.

  4. Dicer-1-dependent Dacapo suppression acts downstream of Insulin receptor in regulating cell division of Drosophila germline stem cells.

    PubMed

    Yu, Jenn-Yah; Reynolds, Steven H; Hatfield, Steve D; Shcherbata, Halyna R; Fischer, Karin A; Ward, Ellen J; Long, Dang; Ding, Ye; Ruohola-Baker, Hannele

    2009-05-01

    It is important to understand the regulation of stem cell division because defects in this process can cause altered tissue homeostasis or cancer. The cyclin-dependent kinase inhibitor Dacapo (Dap), a p21/p27 homolog, acts downstream of the microRNA (miRNA) pathway to regulate the cell cycle in Drosophila melanogaster germline stem cells (GSCs). Tissue-extrinsic signals, including insulin, also regulate cell division of GSCs. We report that intrinsic and extrinsic regulators intersect in GSC division control; the Insulin receptor (InR) pathway regulates Dap levels through miRNAs, thereby controlling GSC division. Using GFP-dap 3'UTR sensors in vivo, we show that in GSCs the dap 3'UTR is responsive to Dicer-1, an RNA endonuclease III required for miRNA processing. Furthermore, the dap 3'UTR can be directly targeted by miR-7, miR-278 and miR-309 in luciferase assays. Consistent with this, miR-278 and miR-7 mutant GSCs are partially defective in GSC division and show abnormal cell cycle marker expression, respectively. These data suggest that the GSC cell cycle is regulated via the dap 3'UTR by multiple miRNAs. Furthermore, the GFP-dap 3'UTR sensors respond to InR but not to TGF-beta signaling, suggesting that InR signaling utilizes Dap for GSC cell cycle regulation. We further demonstrate that the miRNA-based Dap regulation may act downstream of InR signaling; Dcr-1 and Dap are required for nutrition-dependent cell cycle regulation in GSCs and reduction of dap partially rescues the cell cycle defect of InR-deficient GSCs. These data suggest that miRNA- and Dap-based cell cycle regulation in GSCs can be controlled by InR signaling.

  5. Dicer-1-dependent Dacapo suppression acts downstream of Insulin receptor in regulating cell division of Drosophila germline stem cells

    PubMed Central

    Yu, Jenn-Yah; Reynolds, Steven H.; Hatfield, Steve D.; Shcherbata, Halyna R.; Fischer, Karin A.; Ward, Ellen J.; Long, Dang; Ding, Ye; Ruohola-Baker, Hannele

    2009-01-01

    Summary It is important to understand the regulation of stem cell division because defects in this process can cause altered tissue homeostasis or cancer. The cyclin-dependent kinase inhibitor Dacapo (Dap), a p21/p27 homolog, acts downstream of the microRNA (miRNA) pathway to regulate the cell cycle in Drosophila melanogaster germline stem cells (GSCs). Tissue-extrinsic signals, including insulin, also regulate cell division of GSCs. We report that intrinsic and extrinsic regulators intersect in GSC division control; the Insulin receptor (InR) pathway regulates Dap levels through miRNAs, thereby controlling GSC division. Using GFP-dap 3′UTR sensors in vivo, we show that in GSCs the dap 3′UTR is responsive to Dicer-1, an RNA endonuclease III required for miRNA processing. Furthermore, the dap 3′UTR can be directly targeted by miR-7, miR-278 and miR-309 in luciferase assays. Consistent with this, miR-278 and miR-7 mutant GSCs are partially defective in GSC division and show abnormal cell cycle marker expression, respectively. These data suggest that the GSC cell cycle is regulated via the dap 3′UTR by multiple miRNAs. Furthermore, the GFP-dap 3′UTR sensors respond to InR but not to TGF-β signaling, suggesting that InR signaling utilizes Dap for GSC cell cycle regulation. We further demonstrate that the miRNA-based Dap regulation may act downstream of InR signaling; Dcr-1 and Dap are required for nutrition-dependent cell cycle regulation in GSCs and reduction of dap partially rescues the cell cycle defect of InR-deficient GSCs. These data suggest that miRNA- and Dap-based cell cycle regulation in GSCs can be controlled by InR signaling. PMID:19336466

  6. Reactive Oxygen Species Regulate Hematopoietic Stem Cell Self-Renewal, Migration and Development, As Well As Their Bone Marrow Microenvironment

    PubMed Central

    Ludin, Aya; Gur-Cohen, Shiri; Golan, Karin; Kaufmann, Kerstin B.; Itkin, Tomer; Medaglia, Chiara; Lu, Xin-Jiang; Ledergor, Guy; Kollet, Orit

    2014-01-01

    Abstract Significance: Blood forming, hematopoietic stem cells (HSCs) mostly reside in the bone marrow in a quiescent, nonmotile state via adhesion interactions with stromal cells and macrophages. Quiescent, proliferating, and differentiating stem cells have different metabolism, and accordingly different amounts of intracellular reactive oxygen species (ROS). Importantly, ROS is not just a byproduct of metabolism, but also plays a role in stem cell state and function. Recent Advances: ROS levels are dynamic and reversibly dictate enhanced cycling and myeloid bias in ROShigh short-term repopulating stem cells, and ROSlow quiescent long-term repopulating stem cells. Low levels of ROS, regulated by intrinsic factors such as cell respiration or nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase) activity, or extrinsic factors such as stem cell factor or prostaglandin E2 are required for maintaining stem cell self-renewal. High ROS levels, due to stress and inflammation, induce stem cell differentiation and enhanced motility. Critical Issues: Stem cells need to be protected from high ROS levels to avoid stem cell exhaustion, insufficient host immunity, and leukemic transformation that may occur during chronic inflammation. However, continuous low ROS production will lead to lack of stem cell function and opportunistic infections. Ultimately, balanced ROS levels are crucial for maintaining the small stem cell pool and host immunity, both in homeostasis and during stress situations. Future Directions: Deciphering the signaling pathway of ROS in HSC will provide a better understanding of ROS roles in switching HSC from quiescence to activation and vice versa, and will also shed light on the possible roles of ROS in leukemia initiation and development. Antioxid. Redox Signal. 21, 1605–1619. PMID:24762207

  7. The Regulation of rRNA Gene Transcription during Directed Differentiation of Human Embryonic Stem Cells

    PubMed Central

    Liu, Zhong; Zhao, Rui; Giles, Keith E.

    2016-01-01

    It has become increasingly clear that proper cellular control of pluripotency and differentiation is related to the regulation of rRNA synthesis. To further our understanding of the role that the regulation of rRNA synthesis has in pluripotency we monitored rRNA synthesis during the directed differentiation of human embryonic stem cells (hESCs). We discovered that the rRNA synthesis rate is reduced ~50% within 6 hours of ACTIVIN A treatment. This precedes reductions in expression of specific stem cell markers and increases in expression of specific germ layer markers. The reduction in rRNA synthesis is concomitant with dissociation of the Pol I transcription factor, UBTF, from the rRNA gene promoter and precedes any increase to heterochromatin throughout the rRNA gene. To directly investigate the role of rRNA synthesis in pluripotency, hESCs were treated with the Pol I inhibitor, CX-5461. The direct reduction of rRNA synthesis by CX-5461 induces the expression of markers for all three germ layers, reduces the expression of pluripotency markers, and is overall similar to the ACTIVIN A induced changes. This work indicates that the dissociation of UBTF from the rRNA gene, and corresponding reduction in transcription, represent early regulatory events during the directed differentiation of pluripotent stem cells. PMID:27299313

  8. The Regulation of rRNA Gene Transcription during Directed Differentiation of Human Embryonic Stem Cells.

    PubMed

    Woolnough, Jessica L; Atwood, Blake L; Liu, Zhong; Zhao, Rui; Giles, Keith E

    2016-01-01

    It has become increasingly clear that proper cellular control of pluripotency and differentiation is related to the regulation of rRNA synthesis. To further our understanding of the role that the regulation of rRNA synthesis has in pluripotency we monitored rRNA synthesis during the directed differentiation of human embryonic stem cells (hESCs). We discovered that the rRNA synthesis rate is reduced ~50% within 6 hours of ACTIVIN A treatment. This precedes reductions in expression of specific stem cell markers and increases in expression of specific germ layer markers. The reduction in rRNA synthesis is concomitant with dissociation of the Pol I transcription factor, UBTF, from the rRNA gene promoter and precedes any increase to heterochromatin throughout the rRNA gene. To directly investigate the role of rRNA synthesis in pluripotency, hESCs were treated with the Pol I inhibitor, CX-5461. The direct reduction of rRNA synthesis by CX-5461 induces the expression of markers for all three germ layers, reduces the expression of pluripotency markers, and is overall similar to the ACTIVIN A induced changes. This work indicates that the dissociation of UBTF from the rRNA gene, and corresponding reduction in transcription, represent early regulatory events during the directed differentiation of pluripotent stem cells.

  9. Mortalin and DJ-1 coordinately regulate hematopoietic stem cell function through the control of oxidative stress.

    PubMed

    Tai-Nagara, Ikue; Matsuoka, Sahoko; Ariga, Hiroyoshi; Suda, Toshio

    2014-01-02

    Hematopoietic stem cells (HSCs) maintain stemness through various mechanisms that protect against stressful conditions. Heat shock proteins (HSPs) preserve cell homeostasis during stress responses through protein quality control, suggesting that HSPs may safeguard HSCs against numerous traumas. Here, we show that mortalin, a mitochondrial HSP, plays an essential role in maintaining HSC properties by regulating oxidative stress. Mortalin is primarily localized in hematopoietic stem and progenitor cell (HSPC) compartments. In this study, the inhibition of mortalin function caused abnormal reactive oxygen species (ROS) elevation in HSCs and reduced HSC numbers. Knockdown (KD) of mortalin in HSPCs impaired their ability to repopulate and form colonies. Moreover, mortalin-KD HSCs could not maintain quiescence and showed severe downregulation of cyclin-dependent kinase inhibitor- and antioxidant-related genes. Conversely, HSCs that overexpressed mortalin maintained a high reconstitution capacity and low ROS levels. Furthermore, DJ-1, one of the genes responsible for Parkinson's disease, directly bound to mortalin and acted as a negative ROS regulator. Using DJ-1-deficient mice, we demonstrated that mortalin and DJ-1 coordinately maintain normal ROS levels and HSC numbers. Collectively, these results indicate that the mortalin/DJ-1 complex guards against mitochondrial oxidative stress and is indispensable for the maintenance of HSCs.

  10. Regulation of mesenchymal stem cell 3D microenvironment: From macro to microfluidic bioreactors.

    PubMed

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

    2016-01-01

    Human mesenchymal stem cells (hMSCs) have emerged as an important cell type in cell therapy and tissue engineering. In these applications, maintaining the therapeutic properties of hMSCs requires tight control of the culture environments and the structural cell organizations. Bioreactor systems are essential tools to achieve these goals in the clinical-scale expansion and tissue engineering applications. This review summarizes how different bioreactors provide cues to regulate the structure and the chemico-mechanical microenvironment of hMSCs with a focus on 3D organization. In addition to conventional bioreactors, recent advances in microfluidic bioreactors as a novel approach to better control the hMSC microenvironment are also discussed. These advancements highlight the key role of bioreactor systems in preserving hMSC's functional properties by providing dynamic and temporal regulation of in vitro cellular microenvironment.

  11. Identification of Bone Marrow-Derived Soluble Factors Regulating Human Mesenchymal Stem Cells for Bone Regeneration.

    PubMed

    Tsai, Tsung-Lin; Li, Wan-Ju

    2017-02-14

    Maintaining properties of human bone marrow-derived mesenchymal stem cells (BMSCs) in culture for regenerative applications remains a great challenge. An emerging approach of constructing a culture environment mimicking the bone marrow niche to regulate BMSC activities has been developed. In this study, we have demonstrated a systematic approach to identify soluble factors of interest extracted from human bone marrow and used them in BMSC culture for tissue regeneration. We have found that lipocalin-2 and prolactin are key factors in bone marrow, involved in regulating BMSC activities. Treating the cell with lipocalin-2 and prolactin delays cellular senescence of BMSCs and primes the cell for osteogenesis and chondrogenesis. We have also demonstrated that BMSCs pretreated with lipocalin-2 and prolactin can enhance the repair of calvarial defects in mice. Together, our study provides research evidence of using a viable approach to prime BMSC properties in vitro for improving cell-based tissue regeneration in vivo.

  12. Advances in Microfluidic Platforms for Analyzing and Regulating Human Pluripotent Stem Cells

    PubMed Central

    Qian, Tongcheng; Shusta, Eric V.; Palecek, Sean P.

    2015-01-01

    Microfluidic devices employ submillimeter length scale control of flow to achieve high-resolution spatial and temporal control over the microenvironment, providing powerful tools to elucidate mechanisms of human pluripotent stem cell (hPSC) regulation and to elicit desired hPSC fates. In addition, microfluidics allow control of paracrine and juxtracrine signaling, thereby enabling fabrication of microphysiological systems comprised of multiple cell types organized into organs-on-a-chip. Microfluidic cell culture systems can also be integrated with actuators and sensors, permitting construction of high-density arrays of cell-based biosensors for screening applications. This review describes recent advances in using microfluidics to understand mechanisms by which the microenvironment regulates hPSC fates and applications of microfluidics to realize the potential of hPSCs for in vitro modeling and screening applications. PMID:26313850

  13. Prediction and testing of novel transcriptional networks regulating embryonic stem cell self-renewal and commitment.

    PubMed

    Walker, Emily; Ohishi, Minako; Davey, Ryan E; Zhang, Wen; Cassar, Paul A; Tanaka, Tetsuya S; Der, Sandy D; Morris, Quaid; Hughes, Timothy R; Zandstra, Peter W; Stanford, William L

    2007-06-07

    Stem cell fate is governed by the integration of intrinsic and extrinsic positive and negative signals upon inherent transcriptional networks. To identify novel embryonic stem cell (ESC) regulators and assemble transcriptional networks controlling ESC fate, we performed temporal expression microarray analyses of ESCs after the initiation of commitment and integrated these data with known genome-wide transcription factor binding. Effects of forced under- or overexpression of predicted novel regulators, defined as differentially expressed genes with potential binding sites for known regulators of pluripotency, demonstrated greater than 90% correspondence with predicted function, as assessed by functional and high-content assays of self-renewal. We next assembled 43 theoretical transcriptional networks in ESCs, 82% (23 out of 28 tested) of which were supported by analysis of genome-wide expression in Oct4 knockdown cells. By using this integrative approach, we have formulated novel networks describing gene repression of key developmental regulators in undifferentiated ESCs and successfully predicted the outcomes of genetic manipulation of these networks.

  14. Realising new health technologies: problems of regulating human stem cells in the USA.

    PubMed

    Warren-Jones, Amanda

    2012-01-01

    Stem cell technology holds the promise of radically changing medicine through the provision of better disease models; the creation of tissue, cells, and organs for therapeutic uses; and the increased personalisation of healthcare. However, the degree to which any of these developments can be realised in the USA rests upon how effective the regulatory environment is in nurturing the technology to market. This article assesses the regulation in terms of its ability to minimise factors which erode the public interest in developing medical innovations (abuse) and promoting them to the market. This requires an overarching review of patent law (and how it fits with anti-trust and contract law); as well as the general regulation of innovation through ethical review, clinical trials, market authorisation, post-market oversight; government lead regulation of stem cells; and finally incorporating the impact of self-regulation by industry. From this assessment, it becomes possible to appreciate that the optimal system of regulation is reliant upon the gentle tweaking of many factors, rather than the wholesale revision of only a few. It also becomes possible to identify that individual tools of regulation have varying impacts. For example, the patent system may be the most open to abuse by individual companies, but as a regulatory framework it has the most mechanisms for dealing with such abuses. However, the biggest impact upon curtailing abuse derives from the self-regulation of the industry. Conversely, government led regulation is open to abuse from political agendas, but it has the greatest capacity to nurture innovation productively.

  15. Magnesium regulates neural stem cell proliferation in the mouse hippocampus by altering mitochondrial function.

    PubMed

    Jia, Shanshan; Mou, Chengzhi; Ma, Yihe; Han, Ruijie; Li, Xue

    2016-04-01

    In the adult brain, neural stem cells from the subgranular zone (SGZ) of the hippocampus and the subventricular zone (SVZ) of the cortex progress through the following five developmental stages: radial glia-like cells, neural progenitor cells, neuroblasts, immature neurons, and mature neurons. These developmental stages are linked to both neuronal microenvironments and energy metabolism. Neurogenesis is restricted and has been demonstrated to arise from tissue microenvironments. We determined that magnesium, a key nutrient in cellular energy metabolism, affects neural stem cell (NSC) proliferation in cells derived from the embryonic hippocampus by influencing mitochondrial function. Densities of proliferating cells and NSCs both showed their highest values at 0.8 mM [Mg(2+) ]o , whereas lower proliferation rates were observed at 0.4 and 1.4 mM [Mg(2+) ]o . The numbers and sizes of the neurospheres reached the maximum at 0.8 mM [Mg(2+) ]o and were weaker under both low (0.4 mM) and high (1.4 mM) concentrations of magnesium. In vitro experimental evidence demonstrates that extracellular magnesium regulates the number of cultured hippocampal NSCs, affecting both magnesium homeostasis and mitochondrial function. Our findings indicate that the effect of [Mg(2+) ]o on NSC proliferation may lie downstream of alterations in mitochondrial function because mitochondrial membrane potential was highest in the NSCs in the moderate [Mg(2+) ]o (0.8 mM) group and lower in both the low (0.4 mM) and high (1.4 mM) [Mg(2+) ]o groups. Overall, these findings demonstrate a new function for magnesium in the brain in the regulation of hippocampal neural stem cells: affecting their cellular energy metabolism. © 2015 International Federation for Cell Biology.

  16. MERIT40 deficiency expands hematopoietic stem cell pools by regulating thrombopoietin receptor signaling

    PubMed Central

    Rozenova, Krasimira; Jiang, Jing; Donaghy, Ryan; Aressy, Bernadette; Greenberg, Roger A.

    2015-01-01

    Hematopoietic stem cell (HSC) self-renewal and multilineage reconstitution are controlled by positive and negative signaling cues with perturbations leading to disease. Lnk is an essential signaling adaptor protein that dampens signaling by the cytokine thrombopoietin (Tpo) to limit HSC expansion. Here, we show that MERIT40 (Mediator of RAP80 Interactions and Targeting 40 kDa [M40]), a core subunit of an Lnk-associated Lys63 deubiquitinating (DUB) complex, attenuates HSC expansion. M40 deficiency increases the size of phenotypic and functional HSC pools. M40−/− HSCs are more resistant to cytoablative stress, and exhibit superior repopulating ability and self-renewal upon serial transplantation. M40−/− HSCs display increased quiescence and decelerated cell cycle kinetics accompanied by downregulation of gene sets associated with cell division. Mechanistically, M40 deficiency triggers hypersensitivity to Tpo stimulation and the stem cell phenotypes are abrogated on a background null for the Tpo receptor Mpl. These results establish M40-containing DUB complexes as novel HSC regulators of HSC expansion, implicate Lys63 ubiquitination in HSC signaling, and point to DUB-specific inhibitors as reagents to expand stem cell populations. PMID:25636339

  17. On the cutting edge of organ renewal: identification, regulation and evolution of incisor stem cells

    PubMed Central

    Hu, Jimmy Kuang-Hsien; Mushegyan, Vagan; Klein, Ophir D.

    2014-01-01

    The rodent incisor is one of a number of organs that grow continuously throughout the life of an animal. Continuous growth of the incisor arose as an evolutionary adaptation to compensate for abrasion at the distal end of the tooth. The sustained turnover of cells that deposit the mineralized dental tissues is made possible by epithelial and mesenchymal stem cells residing at the proximal end of the incisor. A complex network of signaling pathways and transcription factors regulates the formation, maintenance, and differentiation of these stem cells during development and throughout adulthood. Research over the past 15 years has led to significant progress in our understanding of this network, which includes FGF, BMP, Notch, and Hh signaling, as well as cell adhesion molecules and microRNAs. This review surveys key historical experiments that laid the foundation of the field and discusses more recent findings that definitively identified the stem cell population, elucidated the regulatory network, and demonstrated possible genetic mechanisms for the evolution of continuously growing teeth. PMID:24307456

  18. On the cutting edge of organ renewal: Identification, regulation, and evolution of incisor stem cells.

    PubMed

    Kuang-Hsien Hu, Jimmy; Mushegyan, Vagan; Klein, Ophir D

    2014-02-01

    The rodent incisor is one of a number of organs that grow continuously throughout the life of an animal. Continuous growth of the incisor arose as an evolutionary adaptation to compensate for abrasion at the distal end of the tooth. The sustained turnover of cells that deposit the mineralized dental tissues is made possible by epithelial and mesenchymal stem cells residing at the proximal end of the incisor. A complex network of signaling pathways and transcription factors regulates the formation, maintenance, and differentiation of these stem cells during development and throughout adulthood. Research over the past 15 years has led to significant progress in our understanding of this network, which includes FGF, BMP, Notch, and Hh signaling, as well as cell adhesion molecules and micro-RNAs. This review surveys key historical experiments that laid the foundation of the field and discusses more recent findings that definitively identified the stem cell population, elucidated the regulatory network, and demonstrated possible genetic mechanisms for the evolution of continuously growing teeth.

  19. Regulation of Embryonic Stem Cell Self-Renewal and Differentiation by MicroRNAs.

    PubMed

    Ran, Xi; Xiao, Chun-Hong; Xiang, Gui-Ming; Ran, Xin-Ze

    2017-03-09

    MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression. They play an important role in various cellular processes such as apoptosis, differentiation, secretion, and proliferation. Embryonic stem cells (ESCs) are derived from the inner cell mass of the blastocyst stage of the embryo. miRNAs are critical factors for the self-renewal and differentiation of ESCs. In this review, we will focus on the role of miRNAs in the self-renewal and directional differentiation of ESCs. We will present the current knowledge on key points related to miRNA biogenesis and their function in ESCs.

  20. [Ideological conflicts leading to regulation of investigation with embryonic stem cells].

    PubMed

    Brena, Ingrid

    2015-01-01

    Human stem cells, particularly embryonic, have huge therapeutic potential to many degenerative diseases, so they are the subject of intense research in many countries. Because obtaining human stem cells involves the use of zygotes obtained by in vitro fertilization, when they arrive in the blastocyst stage, ethical issues arise that some groups considered insurmountable; in Mexico to date it has not been possible to established a law or rule that regulates the issue. The purpose of this paper is to discuss the ideological conflicts that have led to this situation, and about the light a judgment delivered by the Inter-American Court of Human Rights may shed on a democratic and secular legislation.

  1. Functional regulation of FoxO1 in neural stem cell differentiation

    PubMed Central

    Kim, D-Y; Hwang, I; Muller, F L; Paik, J-H

    2015-01-01

    Forkhead transcription factor family O (FoxO) maintains adult stem cell reserves by supporting their long-term proliferative potential. MicroRNAs (miRs) regulate neuronal stem/progenitor cell (NSPC) proliferation and differentiation during neural development by controlling the expression of a specific set of target genes. In the neurogenic subventricular zone, FoxO1 is specifically expressed in NSPCs and is no longer detected during the transition to neuroblast stage, forming an inverse correlation with miR-9 expression. The 3′-untranslated region of FoxO1 contains a conserved target sequence of miR-9 and FoxO1 expression is coordinated in concert with miR-9 during neuronal differentiation. Our study demonstrates that FoxO1 contributes to NSPC fate decision through its cooperation with the Notch signaling pathway. PMID:26470727

  2. The changing landscape of European and international regulation on embryonic stem cell research.

    PubMed

    Elstner, A; Damaschun, A; Kurtz, A; Stacey, G; Arán, B; Veiga, A; Borstlap, J

    2009-03-01

    Legislation in individual member states of the European Union on human embryonic stem cell (hESC) research is as divergent as the different cultural, ethical, and religious views on the issue. On the occasion of the public launch of the European Human Embryonic Stem Cell Registry (hESCreg: www.hescreg.eu), a two-day symposium was held on 18 and 19 January 2008 in Berlin to offer participants an overview of state-of-the-art hESC research and legislation throughout Europe and in selected regions of the world. Thirty leading scientists from Europe as well as from the United States, Japan, and Australia reported on a range of aspects related to research on hESC and reviewed the key elements of the newly established hESCreg database of hESC lines. In this article we summarize and complete the information on the current status of international hESC regulation.

  3. Regulation of long-term repopulating hematopoietic stem cells by EPCR/PAR1 signaling

    PubMed Central

    Gur-Cohen, Shiri; Kollet, Orit; Graf, Claudine; Esmon, Charles T.; Ruf, Wolfram; Lapidot, Tsvee

    2016-01-01

    The common developmental origin of endothelial and hematopoietic cells is manifested by coexpression of several cell surface receptors. Adult murine bone marrow (BM) long-term repopulating hematopoietic stem cells (LT-HSCs), endowed with the highest repopulation and self-renewal potential, express endothelial protein C receptor (EPCR), which is used as a marker to isolate them. EPCR/PAR1 signaling in endothelial cells has anticoagulant and anti-inflammatory roles, while thrombin/PAR1 signaling induces coagulation and inflammation. Recent studies define two new PAR1-mediated signaling cascades that regulate EPCR+ LT-HSC BM retention and egress. EPCR/PAR1 signaling facilitates LT-HSC BM repopulation, retention, survival, and chemotherapy resistance by restricting nitric oxide (NO) production, maintaining NOlow LT-HSC BM retention with increased VLA4 expression, affinity, and adhesion. Conversely, acute stress and clinical mobilization upregulate thrombin generation and activate different PAR1 signaling which overcomes BM EPCR+ LT-HSC retention, inducing their recruitment to the bloodstream. Thrombin/PAR1 signaling induces NO generation, TACE-mediated EPCR shedding, and upregulation of CXCR4 and PAR1, leading to CXCL12-mediated stem and progenitor cell mobilization. This review discusses new roles for factors traditionally viewed as coagulation related, which independently act in the BM to regulate PAR1 signaling in bone- and blood-forming progenitor cells, navigating their fate by controlling NO production. PMID:26928241

  4. Cytohesin 1 regulates homing and engraftment of human hematopoietic stem and progenitor cells

    PubMed Central

    Foster, Katie; Potrzebowska, Katarzyna; Miharada, Natsumi; Torngren, Therese; Bonnet, Dominique

    2017-01-01

    Adhesion is a key component of hematopoietic stem cell regulation mediating homing and retention to the niche in the bone marrow. Here, using an RNA interference screen, we identify cytohesin 1 (CYTH1) as a critical mediator of adhesive properties in primary human cord blood–derived hematopoietic stem and progenitor cells (HSPCs). Knockdown of CYTH1 disrupted adhesion of HSPCs to primary human mesenchymal stroma cells. Attachment to fibronectin and ICAM1, 2 integrin ligands, was severely impaired, and CYTH1-deficient cells showed a reduced integrin β1 activation response, suggesting that CYTH1 mediates integrin-dependent functions. Transplantation of CYTH1-knockdown cells to immunodeficient mice resulted in significantly lower long-term engraftment levels, associated with a reduced capacity of the transplanted cells to home to the bone marrow. Intravital microscopy showed that CYTH1 deficiency profoundly affects HSPC mobility and localization within the marrow space and thereby impairs proper lodgment into the niche. Thus, CYTH1 is a novel major regulator of adhesion and engraftment in human HSPCs through mechanisms that, at least in part, involve the activation of integrins. PMID:27899358

  5. MiR-19a regulates the cell growth and apoptosis of osteosarcoma stem cells by targeting PTEN.

    PubMed

    Zhao, Di; Chen, Youbin; Chen, Shunliang; Zheng, Chuangyi; Hu, Jun; Luo, Shaowei

    2017-05-01

    MicroRNAs are small, endogenous, and non-coding RNAs that play important regulatory roles in multiple biological processes in cancers. Recent evidence has indicated that miR-19a participates in the cancer tumorigenic progression. However, the functional roles of miR-19a in cancer stem cells are still unclear. As the cancer stem cells are considered to be responsible for the tumor recurrence and treatment failure in osteosarcoma, the aim of this study is to investigate the molecular mechanism of miR-19a underlying osteosarcoma tumorigenesis. In this study, we observed significant upregulation of miR-19a in osteosarcoma patients' tumor tissues as well as the osteosarcoma cell lines in vitro. We showed that knockdown of miR-19a by its antisense oligonucleotide (anti-miR-19a) significantly decreased the population of cancer stem cells in osteosarcoma cell lines. Furthermore, we found the miR-19a regulated the cell proliferation, migration, and viability in the human osteosarcoma-cancer stem cells. The gene of phosphatase and tensin homolog deleted on chromosome 10, which is an important tumor suppressor, was found to be directly regulated by miR-19a in human osteosarcoma-cancer stem cells. We demonstrated that knockdown of miR-19a increased the expression of phosphatase and tensin homolog deleted on chromosome 10. As the anti-miR-19a inhibited the phosphatidylinositol 3-kinase/AKT pathway and induced apoptosis of human osteosarcoma-cancer stem cells, the phosphatase and tensin homolog deleted on chromosome 10 small interfering RNA inhibited the effect of it. Meanwhile, the phosphatase and tensin homolog deleted on chromosome 10 small interfering RNA also abolished the effect of anti-miR-19a on inhibiting the cell proliferation, migration, and viability in the human osteosarcoma-cancer stem cells. In conclusion, our findings demonstrated that dysregulation of miR-19a plays critical roles in the osteosarcoma stem cells, at least in part via targeting the phosphatase and

  6. Dystrophin expression in muscle stem cells regulates their polarity and asymmetric division.

    PubMed

    Dumont, Nicolas A; Wang, Yu Xin; von Maltzahn, Julia; Pasut, Alessandra; Bentzinger, C Florian; Brun, Caroline E; Rudnicki, Michael A

    2015-12-01

    Dystrophin is expressed in differentiated myofibers, in which it is required for sarcolemmal integrity, and loss-of-function mutations in the gene that encodes it result in Duchenne muscular dystrophy (DMD), a disease characterized by progressive and severe skeletal muscle degeneration. Here we found that dystrophin is also highly expressed in activated muscle stem cells (also known as satellite cells), in which it associates with the serine-threonine kinase Mark2 (also known as Par1b), an important regulator of cell polarity. In the absence of dystrophin, expression of Mark2 protein is downregulated, resulting in the inability to localize the cell polarity regulator Pard3 to the opposite side of the cell. Consequently, the number of asymmetric divisions is strikingly reduced in dystrophin-deficient satellite cells, which also display a loss of polarity, abnormal division patterns (including centrosome amplification), impaired mitotic spindle orientation and prolonged cell divisions. Altogether, these intrinsic defects strongly reduce the generation of myogenic progenitors that are needed for proper muscle regeneration. Therefore, we conclude that dystrophin has an essential role in the regulation of satellite cell polarity and asymmetric division. Our findings indicate that muscle wasting in DMD not only is caused by myofiber fragility, but also is exacerbated by impaired regeneration owing to intrinsic satellite cell dysfunction.

  7. Which bank? A guardian model for regulation of embryonic stem cell research in Australia.

    PubMed

    McLennan, A

    2007-08-01

    In late 2005 the Legislation Review: Prohibition of Human Cloning Act 2002 (Cth) and the Research Involving Human Embryos Act 2002 (Cth) recommended the establishment of an Australian stem cell bank. This article aims to address a lack of discussion of issues surrounding stem cell banking by suggesting possible answers to the questions of whether Australia should establish a stem cell bank and what its underlying philosophy and functions should be. Answers are developed through an analysis of regulatory, scientific and intellectual property issues relating to embryonic stem cell research in the United Kingdom, United States and Australia. This includes a detailed analysis of the United Kingdom Stem Cell Bank. It is argued that a "guardian" model stem cell bank should be established in Australia. This bank would aim to promote the maximum public benefit from human embryonic stem cell research by providing careful regulatory oversight and addressing ethical issues, while also facilitating research by addressing practical scientific concerns and intellectual property issues.

  8. Basolateral Junction Proteins Regulate Competition for the Follicle Stem Cell Niche in the Drosophila Ovary

    PubMed Central

    Klein, Allon M.; Nystul, Todd G.

    2014-01-01

    Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones. PMID:24991805

  9. Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

    PubMed

    Kronen, Maria R; Schoenfelder, Kevin P; Klein, Allon M; Nystul, Todd G

    2014-01-01

    Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.

  10. Feedback Regulation in a Cancer Stem Cell Model can Cause an Allee Effect

    PubMed Central

    Konstorum, Anna; Hillen, Thomas; Lowengrub, John

    2016-01-01

    The exact mechanisms of spontaneous tumor remission or complete response to treatment are phenomena in oncology that are not completely understood. We use a concept from ecology, the Allee effect, to help explain tumor extinction in a model of tumor growth that incorporates feedback regulation of stem cell dynamics, which occurs in many tumor types where certain signaling molecules, such as Wnts, are upregulated. Due to feedback and the Allee effect, a tumor may become extinct spontaneously or after therapy even when the entire tumor has not been eradicated by the end of therapy. We quantify the Allee effect using an ‘Allee index’ that approximates the area of the basin of attraction for tumor extinction. We show that effectiveness of combination therapy in cancer treatment may occur due to the increased probability that the system will be in the Allee region after combination treatment versus monotherapy. We identify therapies that can attenuate stem cell self-renewal, alter the Allee region and increase its size. We also show that decreased response of tumor cells to growth inhibitors can reduce the size of the Allee region and increase stem cell densities, which may help to explain why this phenomenon is a hallmark of cancer. PMID:27113934

  11. Feedback Regulation in a Cancer Stem Cell Model can Cause an Allee Effect.

    PubMed

    Konstorum, Anna; Hillen, Thomas; Lowengrub, John

    2016-04-01

    The exact mechanisms of spontaneous tumor remission or complete response to treatment are phenomena in oncology that are not completely understood. We use a concept from ecology, the Allee effect, to help explain tumor extinction in a model of tumor growth that incorporates feedback regulation of stem cell dynamics, which occurs in many tumor types where certain signaling molecules, such as Wnts, are upregulated. Due to feedback and the Allee effect, a tumor may become extinct spontaneously or after therapy even when the entire tumor has not been eradicated by the end of therapy. We quantify the Allee effect using an 'Allee index' that approximates the area of the basin of attraction for tumor extinction. We show that effectiveness of combination therapy in cancer treatment may occur due to the increased probability that the system will be in the Allee region after combination treatment versus monotherapy. We identify therapies that can attenuate stem cell self-renewal, alter the Allee region and increase its size. We also show that decreased response of tumor cells to growth inhibitors can reduce the size of the Allee region and increase stem cell densities, which may help to explain why this phenomenon is a hallmark of cancer.

  12. The Mll2 branch of the COMPASS family regulates bivalent promoters in mouse embryonic stem cells.

    PubMed

    Hu, Deqing; Garruss, Alexander S; Gao, Xin; Morgan, Marc A; Cook, Malcolm; Smith, Edwin R; Shilatifard, Ali

    2013-09-01

    Promoters of many developmentally regulated genes, in the embryonic stem cell state, have a bivalent mark of H3K27me3 and H3K4me3, proposed to confer precise temporal activation upon differentiation. Although Polycomb repressive complex 2 is known to implement H3K27 trimethylation, the COMPASS family member responsible for H3K4me3 at bivalently marked promoters was previously unknown. Here, we identify Mll2 (KMT2b) as the enzyme catalyzing H3K4 trimethylation at bivalentlymarked promoters in embryonic stem cells. Although H3K4me3 at bivalent genes is proposed to prime future activation, we detected no substantial defect in rapid transcriptional induction after retinoic acid treatment in Mll2-depleted cells. Our identification of the Mll2 complex as the COMPASS family member responsible for H3K4me3 marking bivalent promoters provides an opportunity to reevaluate and experimentally test models for the function of bivalency in the embryonic stem cell state and in differentiation.

  13. Surface Curvature Differentially Regulates Stem Cell Migration and Differentiation via Altered Attachment Morphology and Nuclear Deformation.

    PubMed

    Werner, Maike; Blanquer, Sébastien B G; Haimi, Suvi P; Korus, Gabriela; Dunlop, John W C; Duda, Georg N; Grijpma, Dirk W; Petersen, Ansgar

    2017-02-01

    Signals from the microenvironment around a cell are known to influence cell behavior. Material properties, such as biochemical composition and substrate stiffness, are today accepted as significant regulators of stem cell fate. The knowledge of how cell behavior is influenced by 3D geometric cues is, however, strongly limited despite its potential relevance for the understanding of tissue regenerative processes and the design of biomaterials. Here, the role of surface curvature on the migratory and differentiation behavior of human mesenchymal stem cells (hMSCs) has been investigated on 3D surfaces with well-defined geometric features produced by stereolithography. Time lapse microscopy reveals a significant increase of cell migration speed on concave spherical compared to convex spherical structures and flat surfaces resulting from an upward-lift of the cell body due to cytoskeletal forces. On convex surfaces, cytoskeletal forces lead to substantial nuclear deformation, increase lamin-A levels and promote osteogenic differentiation. The findings of this study demonstrate a so far missing link between 3D surface curvature and hMSC behavior. This will not only help to better understand the role of extracellular matrix architecture in health and disease but also give new insights in how 3D geometries can be used as a cell-instructive material parameter in the field of biomaterial-guided tissue regeneration.

  14. Single-cell RNA-seq reveals novel regulators of human embryonic stem cell differentiation to definitive endoderm.

    PubMed

    Chu, Li-Fang; Leng, Ning; Zhang, Jue; Hou, Zhonggang; Mamott, Daniel; Vereide, David T; Choi, Jeea; Kendziorski, Christina; Stewart, Ron; Thomson, James A

    2016-08-17

    Human pluripotent stem cells offer the best available model to study the underlying cellular and molecular mechanisms of human embryonic lineage specification. However, it is not fully understood how individual stem cells exit the pluripotent state and transition towards their respective progenitor states. Here, we analyze the transcriptomes of human embryonic stem cell-derived lineage-specific progenitors by single-cell RNA-sequencing (scRNA-seq). We identify a definitive endoderm (DE) transcriptomic signature that leads us to pinpoint a critical time window when DE differentiation is enhanced by hypoxia. The molecular mechanisms governing the emergence of DE are further examined by time course scRNA-seq experiments, employing two new statistical tools to identify stage-specific genes over time (SCPattern) and to reconstruct the differentiation trajectory from the pluripotent state through mesendoderm to DE (Wave-Crest). Importantly, presumptive DE cells can be detected during the transitory phase from Brachyury (T) (+) mesendoderm toward a CXCR4 (+) DE state. Novel regulators are identified within this time window and are functionally validated on a screening platform with a T-2A-EGFP knock-in reporter engineered by CRISPR/Cas9. Through loss-of-function and gain-of-function experiments, we demonstrate that KLF8 plays a pivotal role modulating mesendoderm to DE differentiation. We report the analysis of 1776 cells by scRNA-seq covering distinct human embryonic stem cell-derived progenitor states. By reconstructing a differentiation trajectory at single-cell resolution, novel regulators of the mesendoderm transition to DE are elucidated and validated. Our strategy of combining single-cell analysis and genetic approaches can be applied to uncover novel regulators governing cell fate decisions in a variety of systems.

  15. Hypoxia-mediated epigenetic regulation of stemness in brain tumor cells.

    PubMed

    Prasad, Authors Pankaj; Arora Mittal, Shivani; Chongtham, Jonita; Mohanty, Sujata; Srivastava, Tapasya

    2017-04-04

    Activation of pluripotency regulatory circuit is an important event in solid tumor progression and the hypoxic microenvironment is known to enhance the stemness feature of some cells. This distinct population of cancer stem cells (CSCs)/tumor initiating cells (TICs) exist in a niche and augment invasion, metastasis and drug resistance. Previously, studies have reported global hypomethylation and site-specific aberrant methylation in gliomas along with other epigenetic modifications as important contributors to genomic instability during glioma progression. Here, we have demonstrated the role of hypoxia-mediated epigenetic modifications in regulating expression of core pluripotency factors, OCT4 and NANOG, in glioma cells. We observe hypoxia-mediated induction of demethylases, TET1 and 3, but not TET2 in our cell-line model. Immunoprecipitation studies reveal active demethylation and direct binding of TET1 and 3 at the Oct4 and Nanog regulatory regions. Tet1 and 3 silencing assays further confirmed induction of the pluripotency pathway involving Oct4, Nanog and Stat3, by these paralogues, although with varying degrees. Knockdown of Tet1 and Tet3 inhibited the formation of neurospheres in hypoxic conditions. We observed independent roles of TET1 and TET3 in differentially regulating pluripotency and differentiation associated genes in hypoxia. Overall this study demonstrates an active demethylation in hypoxia by TET1 and 3 as a mechanism of Oct4 and Nanog overexpression thus contributing to the formation of CSCs in gliomas. This article is protected by copyright. All rights reserved.

  16. Vitamin A-Retinoic Acid Signaling Regulates Hematopoietic Stem Cell Dormancy.

    PubMed

    Cabezas-Wallscheid, Nina; Buettner, Florian; Sommerkamp, Pia; Klimmeck, Daniel; Ladel, Luisa; Thalheimer, Frederic B; Pastor-Flores, Daniel; Roma, Leticia P; Renders, Simon; Zeisberger, Petra; Przybylla, Adriana; Schönberger, Katharina; Scognamiglio, Roberta; Altamura, Sandro; Florian, Carolina M; Fawaz, Malak; Vonficht, Dominik; Tesio, Melania; Collier, Paul; Pavlinic, Dinko; Geiger, Hartmut; Schroeder, Timm; Benes, Vladimir; Dick, Tobias P; Rieger, Michael A; Stegle, Oliver; Trumpp, Andreas

    2017-05-18

    Dormant hematopoietic stem cells (dHSCs) are atop the hematopoietic hierarchy. The molecular identity of dHSCs and the mechanisms regulating their maintenance or exit from dormancy remain uncertain. Here, we use single-cell RNA sequencing (RNA-seq) analysis to show that the transition from dormancy toward cell-cycle entry is a continuous developmental path associated with upregulation of biosynthetic processes rather than a stepwise progression. In addition, low Myc levels and high expression of a retinoic acid program are characteristic for dHSCs. To follow the behavior of dHSCs in situ, a Gprc5c-controlled reporter mouse was established. Treatment with all-trans retinoic acid antagonizes stress-induced activation of dHSCs by restricting protein translation and levels of reactive oxygen species (ROS) and Myc. Mice maintained on a vitamin A-free diet lose HSCs and show a disrupted re-entry into dormancy after exposure to inflammatory stress stimuli. Our results highlight the impact of dietary vitamin A on the regulation of cell-cycle-mediated stem cell plasticity. VIDEO ABSTRACT. Copyright © 2017. Published by Elsevier Inc.

  17. Stem cells clinical trials for cardiac repair: regulation as practical accomplishment.

    PubMed

    Wilson-Kovacs, Dana M; Weber, Susanne; Hauskeller, Christine

    2010-01-01

    Macro-analyses on the regulation of new biomedical objects tend to focus on discursive structures and legislative categories in science policy debates at national and cross-national levels, but overlook how actors engage in regulatory practices on an everyday basis. Based on data from ethnographic fieldwork in British and German clinics, and 32 interviews with medical staff, this article provides an insight into the regulation of adult stem cell research and its clinical implementation. The argument illustrates the enactment of regulation at different stages and highlights the accompanying interpretative strategies employed by the medical personnel involved in the management of clinical trials using patients' own (autologous) stem cells to regenerate damaged cardiac tissue. We argue that the implementation of regulation is a practical accomplishment in both national contexts. The complexities present in this process are instanced by the gradual crystallisation of practices within the organisation of clinical trials. This crystallisation is dependent on exchanges between members of medical teams and external agencies, and is set within a strategic ordering of regulatory measures that are mobilised to legitimise clinical research and reinforce professional interests.

  18. Regulation of spindle orientation and neural stem cell fate in the Drosophila optic lobe

    PubMed Central

    Egger, Boris; Boone, Jason Q; Stevens, Naomi R; Brand, Andrea H; Doe, Chris Q

    2007-01-01

    Background The choice of a stem cell to divide symmetrically or asymmetrically has profound consequences for development and disease. Unregulated symmetric division promotes tumor formation, whereas inappropriate asymmetric division affects organ morphogenesis. Despite its importance, little is known about how spindle positioning is regulated. In some tissues cell fate appears to dictate the type of cell division, whereas in other tissues it is thought that stochastic variation in spindle position dictates subsequent sibling cell fate. Results Here we investigate the relationship between neural progenitor identity and spindle positioning in the Drosophila optic lobe. We use molecular markers and live imaging to show that there are two populations of progenitors in the optic lobe: symmetrically dividing neuroepithelial cells and asymmetrically dividing neuroblasts. We use genetically marked single cell clones to show that neuroepithelial cells give rise to neuroblasts. To determine if a change in spindle orientation can trigger a neuroepithelial to neuroblast transition, we force neuroepithelial cells to divide along their apical/basal axis by misexpressing Inscuteable. We find that this does not induce neuroblasts, nor does it promote premature neuronal differentiation. Conclusion We show that symmetrically dividing neuroepithelial cells give rise to asymmetrically dividing neuroblasts in the optic lobe, and that regulation of spindle orientation and division symmetry is a consequence of cell type specification, rather than a mechanism for generating cell type diversity. PMID:17207270

  19. Regulation of spindle orientation and neural stem cell fate in the Drosophila optic lobe.

    PubMed

    Egger, Boris; Boone, Jason Q; Stevens, Naomi R; Brand, Andrea H; Doe, Chris Q

    2007-01-05

    The choice of a stem cell to divide symmetrically or asymmetrically has profound consequences for development and disease. Unregulated symmetric division promotes tumor formation, whereas inappropriate asymmetric division affects organ morphogenesis. Despite its importance, little is known about how spindle positioning is regulated. In some tissues cell fate appears to dictate the type of cell division, whereas in other tissues it is thought that stochastic variation in spindle position dictates subsequent sibling cell fate. Here we investigate the relationship between neural progenitor identity and spindle positioning in the Drosophila optic lobe. We use molecular markers and live imaging to show that there are two populations of progenitors in the optic lobe: symmetrically dividing neuroepithelial cells and asymmetrically dividing neuroblasts. We use genetically marked single cell clones to show that neuroepithelial cells give rise to neuroblasts. To determine if a change in spindle orientation can trigger a neuroepithelial to neuroblast transition, we force neuroepithelial cells to divide along their apical/basal axis by misexpressing Inscuteable. We find that this does not induce neuroblasts, nor does it promote premature neuronal differentiation. We show that symmetrically dividing neuroepithelial cells give rise to asymmetrically dividing neuroblasts in the optic lobe, and that regulation of spindle orientation and division symmetry is a consequence of cell type specification, rather than a mechanism for generating cell type diversity.

  20. FGF signaling specifies hematopoietic stem cells through its regulation of somitic Notch signaling

    PubMed Central

    Lee, Yoonsung; Manegold, Jennifer E; Kim, Albert D; Pouget, Claire; Stachura, David L; Clements, Wilson K; Traver, David

    2014-01-01

    Hematopoietic stem cells (HSCs) derive from hemogenic endothelial cells of the primitive dorsal aorta (DA) during vertebrate embryogenesis. The molecular mechanisms governing this unique endothelial to hematopoietic transition remain unclear. Here, we demonstrate a novel requirement for fibroblast growth factor (FGF) signaling in HSC emergence. This requirement is non-cell-autonomous, and acts within the somite to bridge the Wnt and Notch signaling pathways. We previously demonstrated that Wnt16 regulates the somitic expression of two Notch ligands, deltaC (dlc) and deltaD (dld), whose combined function is required for HSC fate. How Wnt16 connects to Notch function has remained an open question. Our current studies demonstrate that FGF signaling, via FGF receptor 4 (Fgfr4), mediates a signal transduction pathway between Wnt16 and Dlc, but not Dld, to regulate HSC specification. Our findings demonstrate that FGF signaling acts as a key molecular relay within the developmental HSC niche to instruct HSC fate. PMID:25428693

  1. Regulation of normal and leukemic stem cells through cytokine signaling and the microenvironment.

    PubMed

    Camacho, Virginia; McClearn, Victoria; Patel, Sweta; Welner, Robert S

    2017-05-01

    Leukemias depend on transformed stem cells for their growth and thus these cells represent important therapeutic targets. However, leukemic stem cells resemble normal hematopoietic stem cells (HSCs) with respect to most surface markers, gene expression patterns, and ability to be transplanted. Furthermore, the microenvironment that supports healthy HSCs non-hematopoietic populations, and immune cells correspondingly, the cytokines, adhesion molecules and signal transduction pathways are also impaired during leukemogenesis. This altered environment promotes leukemic growth specifically through pro-inflammatory cytokines. Here, we characterize normal and leukemic signaling, as well as the instructive cues from the neighboring hematopoietic cells and the microenvironment that promote stem cell self-renewal and differentiation.

  2. CDK6 Levels Regulate Quiescence Exit in Human Hematopoietic Stem Cells

    PubMed Central

    Laurenti, Elisa; Frelin, Catherine; Xie, Stephanie; Ferrari, Robin; Dunant, Cyrille F.; Zandi, Sasan; Neumann, Andrea; Plumb, Ian; Doulatov, Sergei; Chen, Jing; April, Craig; Fan, Jian-Bing; Iscove, Norman; Dick, John E.

    2015-01-01

    Summary Regulated blood production is achieved through the hierarchical organization of dormant hematopoietic stem cell (HSC) subsets that differ in self-renewal potential and division frequency, with long-term (LT)-HSCs dividing the least. The molecular mechanisms underlying this variability in HSC division kinetics are unknown. We report here that quiescence exit kinetics are differentially regulated within human HSC subsets through the expression level of CDK6. LT-HSCs lack CDK6 protein. Short-term (ST)-HSCs are also quiescent but contain high CDK6 protein levels that permit rapid cell cycle entry upon mitogenic stimulation. Enforced CDK6 expression in LT-HSCs shortens quiescence exit and confers competitive advantage without impacting function. Computational modeling suggests that this independent control of quiescence exit kinetics inherently limits LT-HSC divisions and preserves the HSC pool to ensure lifelong hematopoiesis. Thus, differential expression of CDK6 underlies heterogeneity in stem cell quiescence states that functionally regulates this highly regenerative system. PMID:25704240

  3. Piwi maintains germline stem cells and oogenesis in Drosophila through negative regulation of Polycomb group proteins.

    PubMed

    Peng, Jamy C; Valouev, Anton; Liu, Na; Lin, Haifan

    2016-03-01

    The Drosophila melanogaster Piwi protein regulates both niche and intrinsic mechanisms to maintain germline stem cells, but its underlying mechanism remains unclear. Here we report that Piwi interacts with Polycomb group complexes PRC1 and PRC2 in niche and germline cells to regulate ovarian germline stem cells and oogenesis. Piwi physically interacts with the PRC2 subunits Su(z)12 and Esc in the ovary and in vitro. Chromatin coimmunoprecipitation of Piwi, the PRC2 enzymatic subunit E(z), histone H3 trimethylated at lysine 27 (H3K27me3) and RNA polymerase II in wild-type and piwi mutant ovaries demonstrates that Piwi binds a conserved DNA motif at ∼ 72 genomic sites and inhibits PRC2 binding to many non-Piwi-binding genomic targets and H3K27 trimethylation. Moreover, Piwi influences RNA polymerase II activities in Drosophila ovaries, likely via inhibiting PRC2. We hypothesize that Piwi negatively regulates PRC2 binding by sequestering PRC2 in the nucleoplasm, thus reducing PRC2 binding to many targets and influencing transcription during oogenesis.

  4. Epigenetic regulation of stem cell maintenance in the Drosophila testis via the nucleosome-remodeling factor NURF.

    PubMed

    Cherry, Christopher M; Matunis, Erika L

    2010-06-04

    Regulation of stem cells depends on both tissue-specific transcriptional regulators and changes in chromatin organization, yet the coordination of these events in endogenous niches is poorly understood. In the Drosophila testis, local JAK-STAT signaling maintains germline and somatic stem cells (GSCs and cyst progenitor cells, or CPCs) in a single niche. Here we show that epigenetic regulation via the nucleosome-remodeling factor (NURF) complex ensures GSC and CPC maintenance by positively regulating JAK-STAT signaling, thereby preventing premature differentiation. Conversely, NURF is not required in early differentiating daughter cells of either lineage. Because three additional ATP-dependent chromatin remodelers (ACF, CHRAC, and dMi-2/NuRD) are dispensable for stem cell maintenance in the testis, epigenetic regulation of stem cells within this niche may rely primarily on NURF. Thus, local signals cooperate with specific chromatin-remodeling complexes in intact niches to coordinately regulate a common set of target genes to prevent premature stem cell differentiation.

  5. Interleukin-15 regulates proliferation and self-renewal of adult neural stem cells

    PubMed Central

    Gómez-Nicola, Diego; Valle-Argos, Beatriz; Pallas-Bazarra, Noemí; Nieto-Sampedro, Manuel

    2011-01-01

    The impact of inflammation is crucial for the regulation of the biology of neural stem cells (NSCs). Interleukin-15 (IL-15) appears as a likely candidate for regulating neurogenesis, based on its well-known mitogenic properties. We show here that NSCs of the subventricular zone (SVZ) express IL-15, which regulates NSC proliferation, as evidenced by the study of IL-15−/− mice and the effects of acute IL-15 administration, coupled to 5-bromo-2′-deoxyuridine/5-ethynyl-2′-deoxyuridine dual-pulse labeling. Moreover, IL-15 regulates NSC differentiation, its deficiency leading to an impaired generation of neuroblasts in the SVZ–rostral migratory stream axis, recoverable through the action of exogenous IL-15. IL-15 expressed in cultured NSCs is linked to self-renewal, proliferation, and differentiation. IL-15–/– NSCs presented deficient proliferation and self-renewal, as evidenced in proliferation and colony-forming assays and the analysis of cell cycle–regulatory proteins. Moreover, IL-15–deficient NSCs were more prone to differentiate than wild-type NSCs, not affecting the cell population balance. Lack of IL-15 led to a defective activation of the JAK/STAT and ERK pathways, key for the regulation of proliferation and differentiation of NSCs. The results show that IL-15 is a key regulator of neurogenesis in the adult and is essential to understanding diseases with an inflammatory component. PMID:21508317

  6. The CD10 enzyme is a key player to identify and regulate human mammary stem cells.

    PubMed

    Bachelard-Cascales, Elodie; Chapellier, Marion; Delay, Emmanuel; Pochon, Gaetan; Voeltzel, Thibault; Puisieux, Alain; Caron de Fromentel, Claude; Maguer-Satta, Véronique

    2010-06-01

    The major components of the mammary ductal tree are an inner layer of luminal cells, an outer layer of myoepithelial cells, and a basement membrane that separates the ducts from the underlying stroma. Cells in the outer layer express CD10, a zinc-dependent metalloprotease that regulates the growth of the ductal tree during mammary gland development. To define the steps in the human mammary lineage at which CD10 acts, we have developed an in vitro assay for human mammary lineage progression. We show that sorting for CD10 and EpCAM cleanly separates progenitors from differentiated luminal cells and that the CD10-high EpCAM-low population is enriched for early common progenitor and mammosphere-forming cells. We also show that sorting for CD10 enriches sphere-forming cells from other tissue types, suggesting that it may provide a simple tool to identify stem or progenitor populations in tissues for which lineage studies are not currently possible. We demonstrate that the protease activity of CD10 and the adhesion function of beta1-integrin are required to prevent differentiation of mammary progenitors. Taken together, our data suggest that integrin-mediated contact with the basement membrane and cleavage of signaling factors by CD10 are key elements in the niche that maintains the progenitor and stem cell pools in the mammary lineage.

  7. Gap junction proteins: master regulators of the planarian stem cell response to tissue maintenance and injury.

    PubMed

    Peiris, T Harshani; Oviedo, Néstor J

    2013-01-01

    Gap junction (GJ) proteins are crucial mediators of cell-cell communication during embryogenesis, tissue regeneration and disease. GJ proteins form plasma membrane channels that facilitate passage of small molecules across cells and modulate signaling pathways and cellular behavior in different tissues. These properties have been conserved throughout evolution, and in most invertebrates GJ proteins are known as innexins. Despite their critical relevance for physiology and disease, the mechanisms by which GJ proteins modulate cell behavior are poorly understood. This review summarizes findings from recent work that uses planarian flatworms as a paradigm to analyze GJ proteins in the complexity of the whole organism. The planarian model allows access to a large pool of adult somatic stem cells (known as neoblasts) that support physiological cell turnover and tissue regeneration. Innexin proteins are present in planarians and play a fundamental role in controlling neoblast behavior. We discuss the possibility that GJ proteins participate as cellular sensors that inform neoblasts about local and systemic physiological demands. We believe that functional analyses of GJ proteins will bring a complementary perspective to studies that focus on the temporal expression of genes. Finally, integrating functional studies along with molecular genetics and epigenetic approaches would expand our understanding of cellular regulation in vivo and greatly enhance the possibilities for rationally modulating stem cell behavior in their natural environment. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Surface Curvature Differentially Regulates Stem Cell Migration and Differentiation via Altered Attachment Morphology and Nuclear Deformation

    PubMed Central

    Werner, Maike; Blanquer, Sébastien B. G.; Haimi, Suvi P.; Korus, Gabriela; Dunlop, John W. C.; Duda, Georg N.; Grijpma, Dirk. W.

    2016-01-01

    Signals from the microenvironment around a cell are known to influence cell behavior. Material properties, such as biochemical composition and substrate stiffness, are today accepted as significant regulators of stem cell fate. The knowledge of how cell behavior is influenced by 3D geometric cues is, however, strongly limited despite its potential relevance for the understanding of tissue regenerative processes and the design of biomaterials. Here, the role of surface curvature on the migratory and differentiation behavior of human mesenchymal stem cells (hMSCs) has been investigated on 3D surfaces with well‐defined geometric features produced by stereolithography. Time lapse microscopy reveals a significant increase of cell migration speed on concave spherical compared to convex spherical structures and flat surfaces resulting from an upward‐lift of the cell body due to cytoskeletal forces. On convex surfaces, cytoskeletal forces lead to substantial nuclear deformation, increase lamin‐A levels and promote osteogenic differentiation. The findings of this study demonstrate a so far missing link between 3D surface curvature and hMSC behavior. This will not only help to better understand the role of extracellular matrix architecture in health and disease but also give new insights in how 3D geometries can be used as a cell‐instructive material parameter in the field of biomaterial‐guided tissue regeneration. PMID:28251054

  9. Innate immunity and the regulation and mobilization of keratinocyte stem cells: are the old players playing a new game?

    PubMed

    Singh, Ashok; Morris, Rebecca J

    2012-09-01

    The skin provides an anatomical barrier to physical, chemical and biological agents. Hence, it is not surprising that it has well-developed innate immunity. What we find surprising is that the CD49f(+) /CD34(+) hair follicle stem cells should have an enriched expression profile of so many genes involved in innate immunity. Do these stem cells require extra protection from environmental insults? Or, could there be a new role for these genes? To probe these questions, we first summarize the roles of some key players in epidermal innate immunity. We next focus on their expression in CD49f(+) /CD34(+) hair follicle stem cells. Then, we consider recent data suggesting a new role for these 'old players' in the regulation and mobilization of haematopoietic and mesenchymal stem cells. Finally, we hypothesize that the 'old players' in these hair follicle stem cells may be playing a 'new game'.

  10. Cell recognition molecule L1 promotes embryonic stem cell differentiation through the regulation of cell surface glycosylation

    SciTech Connect

    Li, Ying; Huang, Xiaohua; An, Yue; Ren, Feng; Yang, Zara Zhuyun; Zhu, Hongmei; Zhou, Lei; He, Xiaowen; Schachner, Melitta; Xiao, Zhicheng; Ma, Keli; Li, Yali

    2013-10-25

    Highlights: •Down-regulating FUT9 and ST3Gal4 expression blocks L1-induced neuronal differentiation of ESCs. •Up-regulating FUT9 and ST3Gal4 expression in L1-ESCs depends on the activation of PLCγ. •L1 promotes ESCs to differentiate into neuron through regulating cell surface glycosylation. -- Abstract: Cell recognition molecule L1 (CD171) plays an important role in neuronal survival, migration, differentiation, neurite outgrowth, myelination, synaptic plasticity and regeneration after injury. Our previous study has demonstrated that overexpressing L1 enhances cell survival and proliferation of mouse embryonic stem cells (ESCs) through promoting the expression of FUT9 and ST3Gal4, which upregulates cell surface sialylation and fucosylation. In the present study, we examined whether sialylation and fucosylation are involved in ESC differentiation through L1 signaling. RNA interference analysis showed that L1 enhanced differentiation of ESCs into neurons through the upregulation of FUT9 and ST3Gal4. Furthermore, blocking the phospholipase Cγ (PLCγ) signaling pathway with either a specific PLCγ inhibitor or knockdown PLCγ reduced the expression levels of both FUT9 and ST3Gal4 mRNAs and inhibited L1-mediated neuronal differentiation. These results demonstrate that L1 promotes neuronal differentiation from ESCs through the L1-mediated enhancement of FUT9 and ST3Gal4 expression.

  11. Matrix Gla protein regulates differentiation of endothelial cells derived from mouse embryonic stem cells.

    PubMed

    Yao, Jiayi; Guihard, Pierre J; Blazquez-Medela, Ana M; Guo, Yina; Liu, Ting; Boström, Kristina I; Yao, Yucheng

    2016-01-01

    Matrix Gla protein (MGP) is an antagonist of bone morphogenetic proteins and expressed in vascular endothelial cells. Lack of MGP causes vascular abnormalities in multiple organs in mice. The objective of this study is to define the role of MGP in early endothelial differentiation. We find that expression of endothelial markers is highly induced in Mgp null organs, which, in wild type, contain high MGP expression. Furthermore, Mgp null embryonic stem cells express higher levels of endothelial markers than wild-type controls and an abnormal temporal pattern of expression. We also find that the Mgp-deficient endothelial cells adopt characteristics of mesenchymal stem cells. We conclude that loss of MGP causes dysregulation of early endothelial differentiation.

  12. Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells.

    PubMed

    Caballano-Infantes, Estefania; Terron-Bautista, José; Beltrán-Povea, Amparo; Cahuana, Gladys M; Soria, Bernat; Nabil, Hajji; Bedoya, Francisco J; Tejedo, Juan R

    2017-02-26

    Mitochondrial dysfunction and endoplasmic reticulum stress (ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide (NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca(2+) flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstrated the need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies.

  13. Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells

    PubMed Central

    Caballano-Infantes, Estefania; Terron-Bautista, José; Beltrán-Povea, Amparo; Cahuana, Gladys M; Soria, Bernat; Nabil, Hajji; Bedoya, Francisco J; Tejedo, Juan R

    2017-01-01

    Mitochondrial dysfunction and endoplasmic reticulum stress (ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide (NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca2+ flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstrated the need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies. PMID:28289506

  14. Wnt signaling-mediated redox regulation maintains the germ line stem cell differentiation niche

    PubMed Central

    Wang, Su; Gao, Yuan; Song, Xiaoqing; Ma, Xing; Zhu, Xiujuan; Mao, Ying; Yang, Zhihao; Ni, Jianquan; Li, Hua; Malanowski, Kathryn E; Anoja, Perera; Park, Jungeun; Haug, Jeff; Xie, Ting

    2015-01-01

    Adult stem cells continuously undergo self-renewal and generate differentiated cells. In the Drosophila ovary, two separate niches control germ line stem cell (GSC) self-renewal and differentiation processes. Compared to the self-renewing niche, relatively little is known about the maintenance and function of the differentiation niche. In this study, we show that the cellular redox state regulated by Wnt signaling is critical for the maintenance and function of the differentiation niche to promote GSC progeny differentiation. Defective Wnt signaling causes the loss of the differentiation niche and the upregulated BMP signaling in differentiated GSC progeny, thereby disrupting germ cell differentiation. Mechanistically, Wnt signaling controls the expression of multiple glutathione-S-transferase family genes and the cellular redox state. Finally, Wnt2 and Wnt4 function redundantly to maintain active Wnt signaling in the differentiation niche. Therefore, this study has revealed a novel strategy for Wnt signaling in regulating the cellular redox state and maintaining the differentiation niche. DOI: http://dx.doi.org/10.7554/eLife.08174.001 PMID:26452202

  15. Kindlin-1 controls Wnt and TGF-β availability to regulate cutaneous stem cell proliferation.

    PubMed

    Rognoni, Emanuel; Widmaier, Moritz; Jakobson, Madis; Ruppert, Raphael; Ussar, Siegfried; Katsougkri, Despoina; Böttcher, Ralph T; Lai-Cheong, Joey E; Rifkin, Daniel B; McGrath, John A; Fässler, Reinhard

    2014-04-01

    Kindlin-1 is an integrin tail binding protein that controls integrin activation. Mutations in the FERMT-1 gene, which encodes for Kindlin-1, lead to Kindler syndrome in man, which is characterized by skin blistering, premature skin aging and skin cancer of unknown etiology. Here we show that loss of Kindlin-1 in mouse keratinocytes recapitulates Kindler syndrome and also produces enlarged and hyperactive stem cell compartments, which lead to hyperthickened epidermis, ectopic hair follicle development and increased skin tumor susceptibility. Mechanistically, Kindlin-1 controls keratinocyte adhesion through β1-class integrins and proliferation and differentiation of cutaneous epithelial stem cells by promoting α(v)β(6) integrin-mediated transforming growth factor-β (TGF-β) activation and inhibiting Wnt-β-catenin signaling through integrin-independent regulation of Wnt ligand expression. Our findings assign Kindlin-1 the previously unknown and essential task of controlling cutaneous epithelial stem cell homeostasis by balancing TGF-β-mediated growth-inhibitory signals and Wnt-β-catenin-mediated growth-promoting signals.

  16. Embryonic Stem Cell Growth Factors Regulate eIF2α Phosphorylation

    PubMed Central

    Friend, Kyle; Brooks, Hunter A.; Propson, Nicholas E.; Thomson, James A.; Kimble, Judith

    2015-01-01

    Growth factors and transcription factors are well known to regulate pluripotent stem cells, but less is known about translational control in stem cells. Here, we use embryonic stem cells (ESCs) to investigate a connection between ESC growth factors and eIF2α-mediated translational control (eIF2α phosphorylation promotes protein expression from mRNAs with upstream open-reading frames, or uORFs). We find abundant phosphorylated P-eIF2α (P-eIF2α) in both pluripotent mouse and human ESCs, but little P-eIF2α in ESCs triggered to differentiate. We show that the growth factors LIF (leukemia inhibitory factor) and BMP4 (bone morphogenic protein 4) both maintain P-eIF2α in mESCs, but use distinct mechanisms: LIF inhibits an eIF2α phosphatase whereas BMP4 activates an eIF2α kinase. The mRNAs encoding the pluripotency factors Nanog and c-Myc possess uORFs while Oct4 mRNA does not. We find that salubrinal, a chemical that increases eIF2α phosphorylation, promotes Nanog and c-Myc expression, but not Oct4 expression. These experiments connect ESC growth factors to eIF2α phosphorylation and suggest a chemical substitute for LIF to enhance Nanog and c-Myc expression. PMID:26406898

  17. ZFP521 regulates murine hematopoietic stem cell function and facilitates MLL-AF9 leukemogenesis in mouse and human cells.

    PubMed

    Garrison, Brian S; Rybak, Adrian P; Beerman, Isabel; Heesters, Balthasar; Mercier, Francois E; Scadden, David T; Bryder, David; Baron, Roland; Rossi, Derrick J

    2017-08-03

    The concept that tumor-initiating cells can co-opt the self-renewal program of endogenous stem cells as a means of enforcing their unlimited proliferative potential is widely accepted, yet identification of specific factors that regulate self-renewal of normal and cancer stem cells remains limited. Using a comparative transcriptomic approach, we identify ZNF521/Zfp521 as a conserved hematopoietic stem cell (HSC)-enriched transcription factor in human and murine hematopoiesis whose function in HSC biology remains elusive. Competitive serial transplantation assays using Zfp521-deficient mice revealed that ZFP521 regulates HSC self-renewal and differentiation. In contrast, ectopic expression of ZFP521 in HSCs led to a robust maintenance of progenitor activity in vitro. Transcriptional analysis of human acute myeloid leukemia (AML) patient samples revealed that ZNF521 is highly and specifically upregulated in AMLs with MLL translocations. Using an MLL-AF9 murine leukemia model and serial transplantation studies, we show that ZFP521 is not required for leukemogenesis, although its absence leads to a significant delay in leukemia onset. Furthermore, knockdown of ZNF521 reduced proliferation in human leukemia cell lines possessing MLL-AF9 translocations. Taken together, these results identify ZNF521/ZFP521 as a critical regulator of HSC function, which facilitates MLL-AF9-mediated leukemic disease in mice.

  18. p53 regulates cell cycle and microRNAs to promote differentiation of human embryonic stem cells.

    PubMed

    Jain, Abhinav K; Allton, Kendra; Iacovino, Michelina; Mahen, Elisabeth; Milczarek, Robert J; Zwaka, Thomas P; Kyba, Michael; Barton, Michelle Craig

    2012-01-01

    Multiple studies show that tumor suppressor p53 is a barrier to dedifferentiation; whether this is strictly due to repression of proliferation remains a subject of debate. Here, we show that p53 plays an active role in promoting differentiation of human embryonic stem cells (hESCs) and opposing self-renewal by regulation of specific target genes and microRNAs. In contrast to mouse embryonic stem cells, p53 in hESCs is maintained at low levels in the nucleus, albeit in a deacetylated, inactive state. In response to retinoic acid, CBP/p300 acetylates p53 at lysine 373, which leads to dissociation from E3-ubiquitin ligases HDM2 and TRIM24. Stabilized p53 binds CDKN1A to establish a G(1) phase of cell cycle without activation of cell death pathways. In parallel, p53 activates expression of miR-34a and miR-145, which in turn repress stem cell factors OCT4, KLF4, LIN28A, and SOX2 and prevent backsliding to pluripotency. Induction of p53 levels is a key step: RNA-interference-mediated knockdown of p53 delays differentiation, whereas depletion of negative regulators of p53 or ectopic expression of p53 yields spontaneous differentiation of hESCs, independently of retinoic acid. Ectopic expression of p53R175H, a mutated form of p53 that does not bind DNA or regulate transcription, failed to induce differentiation. These studies underscore the importance of a p53-regulated network in determining the human stem cell state.

  19. ERG promotes T-acute lymphoblastic leukemia and is transcriptionally regulated in leukemic cells by a stem cell enhancer.

    PubMed

    Thoms, Julie A I; Birger, Yehudit; Foster, Sam; Knezevic, Kathy; Kirschenbaum, Yael; Chandrakanthan, Vashe; Jonquieres, Georg; Spensberger, Dominik; Wong, Jason W; Oram, S Helen; Kinston, Sarah J; Groner, Yoram; Lock, Richard; MacKenzie, Karen L; Göttgens, Berthold; Izraeli, Shai; Pimanda, John E

    2011-06-30

    The Ets-related gene (ERG) is an Ets-transcription factor required for normal blood stem cell development. ERG expression is down-regulated during early T-lymphopoiesis but maintained in T-acute lymphoblastic leukemia (T-ALL), where it is recognized as an independent risk factor for adverse outcome. However, it is unclear whether ERG is directly involved in the pathogenesis of T-ALL and how its expression is regulated. Here we demonstrate that transgenic expression of ERG causes T-ALL in mice and that its knockdown reduces the proliferation of human MOLT4 T-ALL cells. We further demonstrate that ERG expression in primary human T-ALL cells is mediated by the binding of other T-cell oncogenes SCL/TAL1, LMO2, and LYL1 in concert with ERG, FLI1, and GATA3 to the ERG +85 enhancer. This enhancer is not active in normal T cells but in transgenic mice targets expression to fetal liver c-kit(+) cells, adult bone marrow stem/progenitors and early CD4(-)CD8(-) double-negative thymic progenitors. Taken together, these data illustrate that ERG promotes T-ALL and that failure to extinguish activity of stem cell enhancers associated with regulatory transcription factors such as ERG can contribute to the development of leukemia.

  20. Tissue inhibitor of metalloproteinases-4 (TIMP-4) regulates stemness in cervical cancer cells.

    PubMed

    Lizarraga, Floria; Espinosa, Magali; Ceballos-Cancino, Gisela; Vazquez-Santillan, Karla; Bahena-Ocampo, Ivan; Schwarz-Cruz Y Celis, Angela; Vega-Gordillo, Montserrat; Garcia Lopez, Patricia; Maldonado, Vilma; Melendez-Zajgla, Jorge

    2016-12-01

    Tissue inhibitor of metalloproteinase-4 (TIMP-4) belongs to a family of extracellular matrix (ECM) metalloproteinases inhibitors that are overexpressed in several cancers. However, the role of TIMP-4 during carcinogenesis is poorly understood. To evaluate TIMP-4 functions in carcinogenesis, stably transfected cells overexpressing this tissue inhibitor were used. Xenograft tumor growth, stem cell enrichment, colony formation, and gene regulation were investigated. Microarrays and in silico analysis were carried out to elucidate TIMP-4 molecular mechanisms. In the present report, we show that in nude mice, cervical cancer cells that overexpress TIMP-4 formed tumors faster than control cell-derived tumors. Furthermore, in vivo limiting dilution assays showed that fewer TIMP-4 overexpressing cells are needed for tumor formation. In vitro analyses demonstrated that TIMP-4 overexpression or exposure to human recombinant TIMP-4 (hrTIMP4) caused an enrichment of the tumor progenitor cell (TPC) population. Accordingly, genome-wide expression and signaling pathway analyses showed that hrTIMP-4 modulated cell survival, cell proliferation, inflammation, and epithelial-mesenchymal transition (EMT) signaling networks. Notably, NFκB signaling pathway appeared to be globally activated upon hrTIMP-4 treatment. Overall, this report provides the first example that TIMP-4 regulates carcinogenesis through enriching the TPC population in cervical cancer cells. Understanding TIMP-4 effects on tumorigenesis may provide clues for future therapies design. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  1. Autophagy Supports Breast Cancer Stem Cell Maintenance by Regulating IL6 Secretion

    PubMed Central

    Maycotte, Paola; Jones, Kenneth L.; Goodall, Megan L.; Thorburn, Jacqueline; Thorburn, Andrew

    2015-01-01

    Autophagy is a mechanism by which cells degrade cellular material to provide nutrients and energy for survival during stress. The autophagy is thought to be a critical process for cancer stem (CSC) or tumor initiating cell maintenance but the mechanisms by which autophagy supports survival of CSCs remain poorly understood. In this study, inhibition of autophagy by knockdown of ATG7 or BECN1 modified the CD44+/CD24low/− population in breast cancer cells by regulating CD24 and IL6 secretion. In a breast cancer cell line that is independent of autophagy for survival, autophagy inhibition increased IL6 secretion to the media. On the other hand, in an autophagy-dependent cell line, autophagy inhibition decreased IL6 secretion, cell survival and mammosphere formation. In these cells, IL6 treatment or conditioned media from autophagy-competent cells rescued the deficiency in mammosphere formation induced by autophagy inhibition. These results reveal that autophagy regulates breast CSC maintenance in autophagy-dependent breast cancer cells by modulating IL6 secretion implicating autophagy as a potential therapeutic target in breast cancer. PMID:25573951

  2. Laser biomodulation on stem cells

    NASA Astrophysics Data System (ADS)

    Liu, Timon C.; Duan, Rui; Li, Yan; Li, Xue-Feng; Tan, Li-Ling; Liu, Songhao

    2001-08-01

    Stem cells are views from the perspectives of their function, evolution, development, and cause. Counterintuitively, most stem cells may arise late in development, to act principally in tissue renewal, thus ensuring an organisms long-term survival. Surprisingly, recent reports suggest that tissue-specific adult stem cells have the potential to contribute to replenishment of multiple adult tissues. Stem cells are currently in the news for two reasons: the successful cultivation of human embryonic stem cell lines and reports that adult stem cells can differentiate into developmentally unrelated cell types, such as nerve cells into blood cells. The spotlight on stem cells has revealed gaps in our knowledge that must be filled if we are to take advantage of their full potential for treating devastating degenerative diseases such as Parkinsons's disease and muscular dystrophy. We need to know more about the intrinsic controls that keep stem cells as stem cells or direct them along particular differentiation pathways. Such intrinsic regulators are, in turn, sensitive to the influences of the microenvironment, or niche, where stem cells normally reside. Both intrinsic and extrinsic signals regular stem cell fate and some of these signals have now been identified. Vacek et al and Wang et al have studied the effect of low intensity laser on the haemopoietic stem cells in vitro. There experiments show there is indeed the effect of low intensity laser on the haemopoietic stem cells in vitro, and the present effect is the promotion of haemopoietic stem cells proliferation. In other words, low intensity laser irradiation can act as an extrinsic signal regulating stem cell fate. In this paper, we study how low intensity laser can be used to regulate stem cell fate from the viewpoint of collective phototransduction.

  3. Reversing breast cancer stem cell into breast somatic stem cell.

    PubMed

    Wijaya, L; Agustina, D; Lizandi, A O; Kartawinata, M M; Sandra, F

    2011-02-01

    Stem cells have an important role in cell biology, allowing tissues to be renewed by freshly created cells throughout their lifetime. The specific micro-environment of stem cells is called stem cell niche; this environment influences the development of stem cells from quiescence through stages of differentiation. Recent advance researches have improved the understanding of the cellular and molecular components of the micro-environment--or niche--that regulates stem cells. We point out an important trend to the study of niche activity in breast cancers. Breast cancer has long been known to conserve a heterogeneous population of cells. While the majority of cells that make up tumors are destined to differentiate and eventually stop dividing, only minority populations of cells, termed cancer stem cell, possess extensive self renewal capability. These cancer stem cells possess characteristics of both stem cells and cancer cells. Breast cancer stem cells reversal to breast somatic stem cells offer a new therapy, that not only can stop the spread of breast cancer cells, but also can differentiate breast cancer stem cells into normal breast somatic stem cells. These can replace damaged breast tissue. Nevertheless, the complexity of realizing this therapy approach needs further research.

  4. MicroRNA miR396 Regulates the Switch between Stem Cells and Transit-Amplifying Cells in Arabidopsis Roots.

    PubMed

    Rodriguez, Ramiro E; Ercoli, María Florencia; Debernardi, Juan Manuel; Breakfield, Natalie W; Mecchia, Martin A; Sabatini, Martin; Cools, Toon; De Veylder, Lieven; Benfey, Philip N; Palatnik, Javier F

    2015-12-01

    To ensure an adequate organ mass, the daughters of stem cells progress through a transit-amplifying phase displaying rapid cell division cycles before differentiating. Here, we show that Arabidopsis thaliana microRNA miR396 regulates the transition of root stem cells into transit-amplifying cells by interacting with GROWTH-REGULATING FACTORs (GRFs). The GRFs are expressed in transit-amplifying cells but are excluded from the stem cells through inhibition by miR396. Inactivation of the GRFs increases the meristem size and induces periclinal formative divisions in transit-amplifying cells. The GRFs repress PLETHORA (PLT) genes, regulating their spatial expression gradient. Conversely, PLT activates MIR396 in the stem cells to repress the GRFs. We identified a pathway regulated by GRF transcription factors that represses stem cell-promoting genes in actively proliferating cells, which is essential for the progression of the cell cycle and the orientation of the cell division plane. If unchecked, the expression of the GRFs in the stem cell niche suppresses formative cell divisions and distorts the organization of the quiescent center. We propose that the interactions identified here between miR396 and GRF and PLT transcription factors are necessary to establish the boundary between the stem cell niche and the transit-amplifying region. © 2015 American Society of Plant Biologists. All rights reserved.

  5. Nono, a Bivalent Domain Factor, Regulates Erk Signaling and Mouse Embryonic Stem Cell Pluripotency.

    PubMed

    Ma, Chun; Karwacki-Neisius, Violetta; Tang, Haoran; Li, Wenjing; Shi, Zhennan; Hu, Haolin; Xu, Wenqi; Wang, Zhentian; Kong, Lingchun; Lv, Ruitu; Fan, Zheng; Zhou, Wenhao; Yang, Pengyuan; Wu, Feizhen; Diao, Jianbo; Tan, Li; Shi, Yujiang Geno; Lan, Fei; Shi, Yang

    2016-10-18

    Nono is a component of the para-speckle, which stores and processes RNA. Mouse embryonic stem cells (mESCs) lack para-speckles, leaving the function of Nono in mESCs unclear. Here, we find that Nono functions as a chromatin regulator cooperating with Erk to regulate mESC pluripotency. We report that Nono loss results in robust self-renewing mESCs with epigenomic and transcriptomic features resembling the 2i (GSK and Erk inhibitors)-induced "ground state." Erk interacts with and is required for Nono localization to a subset of bivalent genes that have high levels of poised RNA polymerase. Nono loss compromises Erk activation and RNA polymerase poising at its target bivalent genes in undifferentiated mESCs, thus disrupting target gene activation and differentiation. These findings argue that Nono collaborates with Erk signaling to regulate the integrity of bivalent domains and mESC pluripotency.

  6. GRK6 regulates ROS response and maintains hematopoietic stem cell self-renewal

    PubMed Central

    Le, Qiumin; Yao, Wenqing; Chen, Yuejun; Yan, Biao; Liu, Cao; Yuan, Man; Zhou, Yuqing; Ma, Lan

    2016-01-01

    G protein-coupled receptor kinases (GRKs) are critically involved in immune response through regulation of cytokine receptors in mature leukocytes, but their role in hematopoiesis is largely unknown. Here, we demonstrate that GRK6 knockout (GRK6−/−) mice exhibit lymphocytopenia, loss of the hematopoietic stem cell (HSC) and multiple progenitor populations. GRK6 deficiency leads to compromised lymphoid differentiation, largely owing to the impairment of HSC self-renewal. Transcriptome and proteomic analysis suggest that GRK6 is involved in reactive oxygen species signaling. GRK6 could interact with DNA-PKcs (DNA-dependent protein kinase, catalytic subunit) and regulate its phosphorylation. Moreover, reactive oxygen species scavenger α-lipoic acid administration could partially rescue the loss of HSC in GRK6−/− mice. Our work demonstrates the importance of GRK6 in regulation of HSC self-renewal and reveals its potential role in participation of stress response. PMID:27882944

  7. TOR signaling regulates planarian stem cells and controls localized and organismal growth.

    PubMed

    Peiris, T Harshani; Weckerle, Frank; Ozamoto, Elyse; Ramirez, Daniel; Davidian, Devon; García-Ojeda, Marcos E; Oviedo, Néstor J

    2012-04-01

    Target of Rapamycin (TOR) controls an evolutionarily conserved signaling pathway that modulates cellular growth and division by sensing levels of nutrients, energy and stress. As such, TOR signaling is a crucial component of tissues and organs that translates systemic signals into cellular behavior. The ubiquitous nature of TOR signaling, together with the difficulty of analyzing tissue during cellular turnover and repair, have limited our understanding of how this kinase operates throughout the body. Here, we use the planarian model system to address TOR regulation at the organismal level. The planarian TOR homolog (Smed-TOR) is ubiquitously expressed, including stem cells (neoblasts) and differentiated tissues. Inhibition of TOR with RNA interference severely restricts cell proliferation, allowing the study of neoblasts with restricted proliferative capacity during regeneration and systemic cell turnover. Strikingly, TOR signaling is required for neoblast response to amputation and localized growth (blastema). However, in the absence of TOR signaling, regeneration takes place only within differentiated tissues. In addition, TOR is essential for maintaining the balance between cell division and cell death, and its dysfunction leads to tissue degeneration and lack of organismal growth in the presence of nutrients. Finally, TOR function is likely to be mediated through TOR Complex 1 as its disruption recapitulates signs of the TOR phenotype. Our data reveal novel roles for TOR signaling in controlling adult stem cells at a systemic level and suggest a new paradigm for studying TOR function during physiological turnover and regeneration.

  8. Telomerase governs immunomodulatory properties of mesenchymal stem cells by regulating FAS ligand expression

    PubMed Central

    Chen, Chider; Akiyama, Kentaro; Yamaza, Takayoshi; You, Yong-Ouk; Xu, Xingtian; Li, Bei; Zhao, Yimin; Shi, Songtao

    2014-01-01

    Bone marrow mesenchymal stem cells (BMMSCs) are capable of differentiating into multiple cell types and regulating immune cell response. However, the mechanisms that govern the immunomodulatory properties of BMMSCs are still not fully elucidated. Here we show that telomerase-deficient BMMSCs lose their capacity to inhibit T cells and ameliorate the disease phenotype in systemic sclerosis mice. Restoration of telomerase activity by telomerase reverse transcriptase (TERT) transfection in TERT−/− BMMSCs rescues their immunomodulatory functions. Mechanistically, we reveal that TERT, combined with β-catenin and BRG1, serves as a transcriptional complex, which binds the FAS ligand (FASL) promoter to upregulate FASL expression, leading to an elevated immunomodulatory function. To test the translational value of these findings in the context of potential clinical therapy, we used aspirin treatment to upregulate telomerase activity in BMMSCs, and found a significant improvement in the immunomodulatory capacity of BMMSCs. Taken together, these findings identify a previously unrecognized role of TERT in improving the immunomodulatory capacity of BMMSCs, suggesting that aspirin treatment is a practical approach to significantly reduce cell dosage in BMMSC-based immunotherapies. Subject Categories Stem Cells; Immunology PMID:24401839

  9. Rab8a vesicles regulate Wnt ligand delivery and Paneth cell maturation at the intestinal stem cell niche

    PubMed Central

    Das, Soumyashree; Yu, Shiyan; Sakamori, Ryotaro; Vedula, Pavan; Feng, Qiang; Flores, Juan; Hoffman, Andrew; Fu, Jiang; Stypulkowski, Ewa; Rodriguez, Alexis; Dobrowolski, Radek; Harada, Akihiro; Hsu, Wei; Bonder, Edward M.; Verzi, Michael P.; Gao, Nan

    2015-01-01

    Communication between stem and niche supporting cells maintains the homeostasis of adult tissues. Wnt signaling is a crucial regulator of the stem cell niche, but the mechanism that governs Wnt ligand delivery in this compartment has not been fully investigated. We identified that Wnt secretion is partly dependent on Rab8a-mediated anterograde transport of Gpr177 (wntless), a Wnt-specific transmembrane transporter. Gpr177 binds to Rab8a, depletion of which compromises Gpr177 traffic, thereby weakening the secretion of multiple Wnts. Analyses of generic Wnt/β-catenin targets in Rab8a knockout mouse intestinal crypts indicate reduced signaling activities; maturation of Paneth cells – a Wnt-dependent cell type – is severely affected. Rab8a knockout crypts show an expansion of Lgr5+ and Hopx+ cells in vivo. However, in vitro, the knockout enteroids exhibit significantly weakened growth that can be partly restored by exogenous Wnts or Gsk3β inhibitors. Immunogold labeling and surface protein isolation identified decreased plasma membrane localization of Gpr177 in Rab8a knockout Paneth cells and fibroblasts. Upon stimulation by exogenous Wnts, Rab8a-deficient cells show ligand-induced Lrp6 phosphorylation and transcriptional reporter activation. Rab8a thus controls Wnt delivery in producing cells and is crucial for Paneth cell maturation. Our data highlight the profound tis