scholarly journals Regulatory network control of blood stem cells

Blood ◽  
2015 ◽  
Vol 125 (17) ◽  
pp. 2614-2620 ◽  
Author(s):  
Berthold Göttgens

Abstract Hematopoietic stem cells (HSCs) are characterized by their ability to execute a wide range of cell fate choices, including self-renewal, quiescence, and differentiation into the many different mature blood lineages. Cell fate decision making in HSCs, as indeed in other cell types, is driven by the interplay of external stimuli and intracellular regulatory programs. Given the pivotal nature of HSC decision making for both normal and aberrant hematopoiesis, substantial research efforts have been invested over the last few decades into deciphering some of the underlying mechanisms. Central to the intracellular decision making processes are transcription factor proteins and their interactions within gene regulatory networks. More than 50 transcription factors have been shown to affect the functionality of HSCs. However, much remains to be learned about the way in which individual factors are connected within wider regulatory networks, and how the topology of HSC regulatory networks might affect HSC function. Nevertheless, important progress has been made in recent years, and new emerging technologies suggest that the pace of progress is likely to accelerate. This review will introduce key concepts, provide an integrated view of selected recent studies, and conclude with an outlook on possible future directions for this field.

Blood ◽  
2008 ◽  
Vol 112 (9) ◽  
pp. 3543-3553 ◽  
Author(s):  
Irving L. Weissman ◽  
Judith A. Shizuru

Advances in the understanding of the cells of the hematopoietic system have provided a rich basis for improving clinical hematopoietic cell transplants; finding and using proteins and molecules to amplify or suppress particular blood cell types; understanding the stepwise progression of preleukemic stages leading first to chronic myeloid disorders, then the emergence of acute blastic leukemias; and treating malignant and nonmalignant diseases with cell subsets. As a result of intense scientific investigation, hematopoietic stem cells (HSCs) have been isolated and their key functional characteristics revealed—self-renewal and multilineage differentiation. These characteristics are now found to be present in all tissue/organ stem cell studies, and even in the analysis of pluripotent embryonic, nuclear transfer, and induced pluripotent stem cells. Studies on HSC have identified hematopoiesis as one of the best systems for studying developmental cell lineages and as the best for understanding molecular changes in cell fate decision-making and for finding preclinical and clinical platforms for tissue and organ replacement, regeneration, and oncogenesis. Here we review the steps, from our viewpoint, that led to HSC isolation and its importance in self-nonself immune recognition.


Cancers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2407
Author(s):  
Ruicen He ◽  
Arthur Dantas ◽  
Karl Riabowol

Acetylation of histones is a key epigenetic modification involved in transcriptional regulation. The addition of acetyl groups to histone tails generally reduces histone-DNA interactions in the nucleosome leading to increased accessibility for transcription factors and core transcriptional machinery to bind their target sequences. There are approximately 30 histone acetyltransferases and their corresponding complexes, each of which affect the expression of a subset of genes. Because cell identity is determined by gene expression profile, it is unsurprising that the HATs responsible for inducing expression of these genes play a crucial role in determining cell fate. Here, we explore the role of HATs in the maintenance and differentiation of various stem cell types. Several HAT complexes have been characterized to play an important role in activating genes that allow stem cells to self-renew. Knockdown or loss of their activity leads to reduced expression and or differentiation while particular HATs drive differentiation towards specific cell fates. In this study we review functions of the HAT complexes active in pluripotent stem cells, hematopoietic stem cells, muscle satellite cells, mesenchymal stem cells, neural stem cells, and cancer stem cells.


Science ◽  
2019 ◽  
Vol 366 (6461) ◽  
pp. 116-120 ◽  
Author(s):  
Nathan D. Lord ◽  
Thomas M. Norman ◽  
Ruoshi Yuan ◽  
Somenath Bakshi ◽  
Richard Losick ◽  
...  

Cell fate decision circuits must be variable enough for genetically identical cells to adopt a multitude of fates, yet ensure that these states are distinct, stably maintained, and coordinated with neighboring cells. A long-standing view is that this is achieved by regulatory networks involving self-stabilizing feedback loops that convert small differences into long-lived cell types. We combined regulatory mutants and in vivo reconstitution with theory for stochastic processes to show that the marquee features of a cell fate switch in Bacillus subtilis—discrete states, multigenerational inheritance, and timing of commitments—can instead be explained by simple stochastic competition between two constitutively produced proteins that form an inactive complex. Such antagonistic interactions are commonplace in cells and could provide powerful mechanisms for cell fate determination more broadly.


2021 ◽  
Vol 22 (18) ◽  
pp. 9667
Author(s):  
Geoffrey Brown

In principle, an oncogene is a cellular gene (proto-oncogene) that is dysfunctional, due to mutation and fusion with another gene or overexpression. Generally, oncogenes are viewed as deregulating cell proliferation or suppressing apoptosis in driving cancer. The cancer stem cell theory states that most, if not all, cancers are a hierarchy of cells that arises from a transformed tissue-specific stem cell. These normal counterparts generate various cell types of a tissue, which adds a new dimension to how oncogenes might lead to the anarchic behavior of cancer cells. It is that stem cells, such as hematopoietic stem cells, replenish mature cell types to meet the demands of an organism. Some oncogenes appear to deregulate this homeostatic process by restricting leukemia stem cells to a single cell lineage. This review examines whether cancer is a legacy of stem cells that lose their inherent versatility, the extent that proto-oncogenes play a role in cell lineage determination, and the role that epigenetic events play in regulating cell fate and tumorigenesis.


2020 ◽  
Vol 21 (6) ◽  
pp. 2247
Author(s):  
Geoffrey Brown ◽  
Lucía Sánchez ◽  
Isidro Sánchez-García

To produce the wide range of blood and immune cell types, haematopoietic stem cells can “choose” directly from the entire spectrum of blood cell fate-options. Affiliation to a single cell lineage can occur at the level of the haematopoietic stem cell and these cells are therefore a mixture of some pluripotent cells and many cells with lineage signatures. Even so, haematopoietic stem cells and their progeny that have chosen a particular fate can still “change their mind” and adopt a different developmental pathway. Many of the leukaemias arise in haematopoietic stem cells with the bulk of the often partially differentiated leukaemia cells belonging to just one cell type. We argue that the reason for this is that an oncogenic insult to the genome “hard wires” leukaemia stem cells, either through development or at some stage, to one cell lineage. Unlike normal haematopoietic stem cells, oncogene-transformed leukaemia stem cells and their progeny are unable to adopt an alternative pathway.


2013 ◽  
Vol 10 (89) ◽  
pp. 20130787 ◽  
Author(s):  
Chunhe Li ◽  
Jin Wang

Cellular differentiation, reprogramming and transdifferentiation are determined by underlying gene regulatory networks. Non-adiabatic regulation via slow binding/unbinding to the gene can be important in these cell fate decision-making processes. Based on a stem cell core gene network, we uncovered the stem cell developmental landscape. As the binding/unbinding speed decreases, the landscape topography changes from bistable attractors of stem and differentiated states to more attractors of stem and other different cell states as well as substates. Non-adiabaticity leads to more differentiated cell types and provides a natural explanation for the heterogeneity observed in the experiments. We quantified Waddington landscapes with two possible cell fate decision mechanisms by changing the regulation strength or regulation timescale (non-adiabaticity). Transition rates correlate with landscape topography through barrier heights between different states and quantitatively determine global stability. We found the optimal speeds of these cell fate decision-making processes. We quantified biological paths and predict that differentiation and reprogramming go through an intermediate state (IM1), whereas transdifferentiation goes through another intermediate state (IM2). Some predictions are confirmed by recent experimental studies.


2020 ◽  
Vol 17 (169) ◽  
pp. 20200500
Author(s):  
Bin Huang ◽  
Mingyang Lu ◽  
Madeline Galbraith ◽  
Herbert Levine ◽  
Jose N. Onuchic ◽  
...  

Stem cells can precisely and robustly undergo cellular differentiation and lineage commitment, referred to as stemness. However, how the gene network underlying stemness regulation reliably specifies cell fates is not well understood. To address this question, we applied a recently developed computational method, ra ndom ci rcuit pe rturbation (RACIPE), to a nine-component gene regulatory network (GRN) governing stemness, from which we identified robust gene states. Among them, four out of the five most probable gene states exhibit gene expression patterns observed in single mouse embryonic cells at 32-cell and 64-cell stages. These gene states can be robustly predicted by the stemness GRN but not by randomized versions of the stemness GRN. Strikingly, we found a hierarchical structure of the GRN with the Oct4/Cdx2 motif functioning as the first decision-making module followed by Gata6/Nanog. We propose that stem cell populations, instead of being viewed as all having a specific cellular state, can be regarded as a heterogeneous mixture including cells in various states. Upon perturbations by external signals, stem cells lose the capacity to access certain cellular states, thereby becoming differentiated. The new gene states and key parameters regulating transitions among gene states proposed by RACIPE can be used to guide experimental strategies to better understand differentiation and design reprogramming. The findings demonstrate that the functions of the stemness GRN is mainly determined by its well-evolved network topology rather than by detailed kinetic parameters.


2020 ◽  
Author(s):  
Eric H. Lee ◽  
Daniel Zinshteyn ◽  
Melissa Wang ◽  
Jessica Reinach ◽  
Cindy Chau ◽  
...  

AbstractStem cells cycle between periods of quiescence and proliferation to promote healthy tissue aging. Once proliferation is initiated, mechanisms that control the balance between self-renewal and differentiation must be engaged to ensure maintenance of stem cell pools until the next quiescent cycle occurs. Here, we demonstrate that dynamic axon-like projections extended by Follicle Stem Cells (FSCs) in the Drosophila ovary control the self-renewal-differentiation balance. Known axon growth regulators still life and sickie are necessary and sufficient for FSC projection growth, mediating organization of germline cyst architecture during follicle formation, controlling targeting of projections to FSCs or germ cells, and regulating expression of the cell fate determinants Eyes Absent (Eya) and Castor (Cas). Our results support a model in which FSC projections function similarly to axons, providing structural organization to a dynamic organ while mediating communication between distinct cell types to effect the key cell fate decision to self-renew or differentiate.


2021 ◽  
Author(s):  
Clara Alsinet ◽  
Maria Primo ◽  
Valentina Lorenzi ◽  
Andrew J Knights ◽  
Carmen Sancho-Serra ◽  
...  

Myeloid cells have a central role in homeostasis and tissue defence. Characterising the current in vitro protocols of myelopoiesis is imperative for their use in research and immunotherapy as well as for understanding the early stages of myeloid differentiation in humans. Here, we profiled the transcriptome of more than 400k cells and generated a robust molecular map of the differentiation of human induced pluripotent stem cells (iPSC) into macrophages. By integrating our in vitro datasets with in vivo single-cell developmental atlases, we found that in vitro macrophage differentiation recapitulates features of in vivo yolk sac hematopoiesis, which happens prior to the appearance of definitive hematopoietic stem cells (HSC). During in vitro myelopoiesis, a wide range of myeloid cells are generated, including erythrocytes, mast cells and monocytes, suggesting that, during early human development, the HSC-independent immune wave gives rise to multiple myeloid cell lineages. We leveraged this model to characterize the transition of hemogenic endothelium into myeloid cells, uncovering poorly described myeloid progenitors and regulatory programs. Taking advantage of the variety of myeloid cells produced, we developed a new protocol to produce type 2 conventional dendritic cells (cDC2) in vitro. We found that the underlying regulatory networks coding for myeloid identity are conserved in vivo and in vitro. Using genetic engineering techniques, we validated the effects of key transcription factors important for cDC2 and macrophage identity and ontogeny. This roadmap of early myeloid differentiation will serve as an important resource for investigating the initial stages of hematopoiesis, which are largely unexplored in humans, and will open up new therapeutic opportunities.


2021 ◽  
Author(s):  
Megan K. Franke ◽  
Adam L. MacLean

The role of cell-cell communication in cell fate decision-making has not been well-characterized through a dynamical systems perspective. To do so, here we develop multiscale models that couple cell-cell communication with cell-internal gene regulatory network dynamics. This allows us to study the influence of external signaling on cell fate decision-making at the resolution of single cells. We study the granulocyte-monocyte vs. megakaryocyte-erythrocyte fate decision, dictated by the GATA1-PU.1 network, as an exemplary bistable cell fate system, modeling the cell-internal dynamic with ordinary differential equations and the cell-cell communication via a Poisson process. We show that, for a wide range of cell communication topologies, subtle changes in signaling can lead to dramatic changes in cell fate. We find that cell-cell coupling can explain how populations of heterogeneous cell types can arise. Analysis of intrinsic and extrinsic cell-cell communication noise demonstrates that noise alone can alter the cell fate decision-making boundaries. These results illustrate how external signals alter transcriptional dynamics, and provide insight into hematopoietic cell fate decision-making.


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