scholarly journals Opposing Wnt and JAK-STAT signaling gradients define a stem cell domain by regulating spatially patterned cell division and differentiation at two borders

2020 ◽  
Author(s):  
David Melamed ◽  
Daniel Kalderon

AbstractMany adult stem cells are maintained as a community by population asymmetry, wherein stochastic actions of individual cells collectively result in a balance between stem cell division and differentiation. We have used Drosophila Follicle Stem Cells (FSCs) as a paradigm to explore the extracellular niche signals that define a stem cell domain and organize stem cell behavior. FSCs produce transit-amplifying Follicle Cells (FCs) from their posterior face and quiescent Escort Cells (ECs) to their anterior. Here we show that JAK-STAT pathway activity, which declines from posterior to anterior, dictates the pattern of divisions over the FSC and EC domains, promotes more posterior FSC locations and conversion to FCs, while opposing EC production. A Wnt pathway gradient of opposite polarity promotes more anterior FSC locations and EC production and opposes FC production. Promotion of both FSC division and conversion to FCs by JAK-STAT signaling buffers the effects of genetically altered pathway activity on FSC numbers and balances the four-fold higher rate of differentiation at the posterior face of the FSC domain with a higher rate of FSC division in the most posterior layer. However, genetic elimination of Wnt pathway activity exacerbated elevated FC production resulting from increased JAK-STAT pathway activity, leading to rapid FSC depletion despite high rates of division. The two pathways combine to define a stem cell domain through concerted effects on FSC differentiation to ECs (high Wnt, low JAK-STAT) and FCs (low Wnt, high JAK-STAT) at each end of opposing signaling gradients, further enforced by quiescence at the anterior border due to declining JAK-STAT pathway activity.

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
David Melamed ◽  
Daniel Kalderon

Many adult stem cell communities are maintained by population asymmetry, where stochastic behaviors of multiple individual cells collectively result in a balance between stem cell division and differentiation. We investigated how this is achieved for Drosophila Follicle Stem Cells (FSCs) by spatially-restricted niche signals. FSCs produce transit-amplifying Follicle Cells (FCs) from their posterior face and quiescent Escort Cells (ECs) to their anterior. We show that JAK-STAT pathway activity, which declines from posterior to anterior, dictates the pattern of divisions over the FSC domain, promotes more posterior FSC locations and conversion to FCs, while opposing EC production. Wnt pathway activity declines from the anterior, promotes anterior FSC locations and EC production, and opposes FC production. The pathways combine to define a stem cell domain through concerted effects on FSC differentiation to ECs and FCs at either end of opposing signaling gradients, and impose a pattern of proliferation that matches derivative production.


2021 ◽  
Author(s):  
Yun-Ruei Kao ◽  
Jiahao Chen ◽  
Rajni Kumari ◽  
Madhuri Tatiparthy ◽  
Yuhong Ma ◽  
...  

Bone marrow resident and rarely dividing haematopoietic stem cells (HSC) harbour an extensive self-renewal capacity to sustain life-long blood formation; albeit their function declines during ageing. Various molecular mechanisms confer stem cell identity, ensure long-term maintenance and are known to be deregulated in aged stem cells. How these programs are coordinated, particularly during cell division, and what triggers their ageing-associated dysfunction has been unknown. Here, we demonstrate that HSC, containing the lowest amount of cytoplasmic chelatable iron (labile iron pool) among hematopoietic cells, activate a limited iron response during mitosis. Engagement of this iron homeostasis pathway elicits mobilization and β-oxidation of arachidonic acid and enhances stem cell-defining transcriptional programs governed by histone acetyl transferase Tip60/KAT5. We further find an age-associated expansion of the labile iron pool, along with loss of Tip60/KAT5-dependent gene regulation to contribute to the functional decline of ageing HSC, which can be mitigated by iron chelation. Together, our work reveals cytoplasmic redox active iron as a novel rheostat in adult stem cells; it demonstrates a role for the intracellular labile iron pool in coordinating a cascade of molecular events which reinforces HSC identity during cell division and to drive stem cell ageing when perturbed. As loss of iron homeostasis is commonly observed in the elderly, we anticipate these findings to trigger further studies into understanding and therapeutic mitigation of labile iron pool-dependent stem cell dysfunction in a wide range of degenerative and malignant pathologies.


2017 ◽  
Author(s):  
Amy Reilein ◽  
David Melamed ◽  
Simon Tavaré ◽  
Daniel Kalderon

SUMMARYCancer-initiating gatekeeper mutations that arise in stem cells would be especially potent if they stabilize and expand an affected stem lineage (1, 2). It is therefore important to understand how different stem cell organization strategies promote or prevent variant stem cell amplification in response to different types of mutation, including those that activate stem cell proliferation. Stem cell numbers can be maintained constant while producing differentiated products through individually asymmetric division outcomes or by population asymmetry strategies, in which individual stem cell lineages necessarily compete for niche space. We considered alternative mechanisms underlying population asymmetry and used quantitative modeling to predict starkly different consequences of altering proliferation rate: a variant, faster-proliferating mutant stem cell should compete better only when stem cell division and differentiation are independent processes. For most types of stem cell it has not been possible to ascertain experimentally whether division and differentiation are coupled. However, Drosophila Follicle Stem Cells (FSCs) provided a favorable model system to investigate population asymmetry mechanisms and also for measuring the impact of altered proliferation on competition. We found from detailed cell lineage studies that FSC division and FSC differentiation are not coupled. We also found that FSC representation, reflecting maintenance and amplification, was highly responsive to genetic changes that altered only the rate of FSC proliferation. The FSC paradigm therefore provides definitive experimental evidence for the general principle that relative proliferation rate will always be a major determinant of competition among stem cells specifically when stem cell division and differentiation are independent.SIGNIFICANCEAdult stem cells support tissue maintenance throughout life but they also can be cells of origin for cancer, allowing clonal expansion and long-term maintenance of the first oncogenic mutations. We considered how a mutation that increases the proliferation rate of a stem cell would affect the probability of its competitive survival and amplification for different potential organizations of stem cells. Quantitative modeling showed that the key characteristic predicting the impact of relative proliferation rate on competition is whether differentiation of a stem cell is coupled to its division. We then used Drosophila Follicle Stem Cells to provide definitive experimental evidence for the general prediction that relative proliferation rates dictate stem cell competition specifically for stem cells that exhibit division-independent differentiation.


2021 ◽  
Author(s):  
Yvonne Wesseling-Rozendaal ◽  
Laurent Holtzer ◽  
Wim Verhaegh ◽  
Anja van de Stolpe

AbstractStem cell research is emerging both as a scientifically and clinically relevant area. One of the current challenges in stem cell research and regenerative medicine is assessment of the pluripotency state of induced pluripotent stem (iPS) cells. Once a stem cell differentiation process is initiated the challenge is how to assess the state of differentiation, and the purity of the differentiated cell population. Stem cell potency and differentiation states are determined by tightly coordinated activity of developmental signaling pathways, such as the Notch, Hedgehog, TGFβ, Wnt, PI3K, MAPK-AP1, and NFκB pathways. Source of the stem cells and culture protocols may influence stem cell phenotype, with potential consequences for pluripotency and in general for experimental reproducibility. Human pluripotent embryonic (hES) and iPS stem cell lines under different culture conditions, organ derived multipotent stem cells, and differentiated cell types, were phenotyped with respect to functional activity of developmental signaling pathways.MethodsWe previously reported on the development and validation of a novel assay platform for quantitative measurement of activity of multiple signal transduction pathways (STP) simultaneously in a single sample, based on interpreting a preselected set of target mRNA expression levels. Assays were used to calculate Notch, Hedgehog, TGFβ, Wnt, PI3K, MAPK-AP1, and NFκB signal transduction pathway activity scores for individual cell samples, using publicly available Affymetrix expression microarray data.ResultsCulture conditions (e.g. mouse versus human feeder) influenced pluripotent stem cell pathway activity profiles. hES and iPS stem cell lines cultured in the same lab under similar conditions showed minimal variation in pathway activity profile despite different genetic backgrounds, while across different labs larger variations were measured, even for the same stem cell line. Pathway activity scores for PI3K, MAPK, Hedgehog, Notch, TGFβ, and NFκB pathways rapidly decreased upon pluripotent stem cell differentiation, while increasing for the Wnt pathway. Further differentiation to intestinal progenitor cells resulted in higher PI3K, Wnt and Notch pathway activity. In multipotent intestinal crypt stem cells obtained from intestinal mucosa samples, similar Notch and even higher Wnt pathway activity were measured, which disappeared upon differentiation to mucosal cells.ConclusionResults support the validity of using these STP assays for quantitative phenotyping of stem cells and differentiated derivatives, and enabled definition of a pluripotency profile with high PI3K, MAPK, Hedgehog, TGFβ, Notch, and NFκB, and low Wnt pathway activity scores.Measurement of combined signaling pathway activity scores is expected to improve experimental reproducibility and standardization of pluripotent and multipotent stem cell culture and differentiation. It enables controlled manipulation of signaling pathway activity using pathway targeting compounds. An envisioned additional utility may lie in quality control for regenerative medicine purposes.


2020 ◽  
Author(s):  
Amy Reilein ◽  
Helen V. Kogan ◽  
Rachel Misner ◽  
Karen Sophia Park ◽  
Daniel Kalderon

SummaryAdult stem cell function relies on the prior specification and organization of appropriate numbers of stem cells and supportive niche cells during development. Insights into those developmental processes could facilitate the synthesis of organoid mimics. Drosophila Follicle Stem Cells (FSCs) present an amenable paradigm with many similarities to mammalian gut stem cells. In an adult germarium a central domain of about 16 FSCs produces a posterior stream of transit-amplifying Follicle Cells (FCs), which encapsulate mature germline cysts to support egg development and, from their anterior face, quiescent Escort Cells (EC), which support the maturation of germline cysts. The behavior of FSCs is guided in part by niche signals produced by ECs and by a specialized polar cell FC derivative. Thus, ECs and FCs are both adult stem cell products and niche cells. Here we show by lineage analyses that adult ECs, FSCs and FCs derive from common precursors during pupal development. We infer that disparities in initial anterior-posterior (AP) precursor location followed by limited dispersal of progeny leads to a gradual acquisition of distinct fates determined by final AP location, with progeny of a single precursor commonly straddling EC and FSC, FSC and FC, or all three territories through most of pupal development. Direct visualization of pupal ovaries, including live imaging revealed a transient population of FC precursors posterior to the developing germarium awaiting emergence of the most mature germline cyst. The consequent budding process was quite different from the budding of egg chambers in adults. An anterior to posterior gradient of Wnt signaling develops shortly after pupariation. Loss of pathway activity cell autonomously resulted in more posterior adult progeny fates, while increased pathway activity elicited the opposite response, suggesting that stronger Wnt signaling favors anterior migration. Clearly detectable JAK-STAT pathway activity emerges only halfway through pupation after polar cells form, and spreads from posterior to anterior. Loss of JAK-STAT activity had similar consequences to increased Wnt pathway activity, drastically reducing FSC and FC production cell autonomously, while increased JAK-STAT activity promoted excessive precursor proliferation. We conclude that FSCs develop in co-ordination with their niche and product cells, that specification of stem cell identity is gradual, subject to stochastic influences and guided by graded extracellular signals, presaging similar regulation of adult stem cell behavior by the same pathways.


2021 ◽  
Vol 16 (1) ◽  
pp. 3-13
Author(s):  
Lang Wang ◽  
Yong Li ◽  
Maorui Zhang ◽  
Kui Huang ◽  
Shuanglin Peng ◽  
...  

Adipose-derived stem cells are adult stem cells which are easy to obtain and multi-potent. Stem-cell therapy has become a promising new treatment for many diseases, and plays an increasingly important role in the field of tissue repair, regeneration and reconstruction. The physicochemical properties of the extracellular microenvironment contribute to the regulation of the fate of stem cells. Nanomaterials have stable particle size, large specific surface area and good biocompatibility, which has led them being recognized as having broad application prospects in the field of biomedicine. In this paper, we review recent developments of nanomaterials in adipose-derived stem cell research. Taken together, the current literature indicates that nanomaterials can regulate the proliferation and differentiation of adipose-derived stem cells. However, the properties and regulatory effects of nanomaterials can vary widely depending on their composition. This review aims to provide a comprehensive guide for future stem-cell research on the use of nanomaterials.


Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Claire Racaud-Sultan ◽  
Nathalie Vergnolle

In adult stem cells, Glycogen Synthase Kinase 3β (GSK3β) is at the crossroad of signaling pathways controlling survival, proliferation, adhesion and differentiation. The microenvironment plays a key role in the regulation of these cell functions and we have demonstrated that the GSK3β activity is strongly dependent on the engagement of integrins and protease-activated receptors (PARs). Downstream of the integrin α5β1 or PAR2 activation, a molecular complex is organized around the scaffolding proteins RACK1 and β-arrestin-2 respectively, containing the phosphatase PP2A responsible for GSK3β activation. As a consequence, a quiescent stem cell phenotype is established with high capacities to face apoptotic and metabolic stresses. A protective role of GSK3β has been found for hematopoietic and intestinal stem cells. Latters survived to de-adhesion through PAR2 activation, whereas formers were protected from cytotoxicity through α5β1 engagement. However, a prolonged activation of GSK3β promoted a defect in epithelial regeneration and a resistance to chemotherapy of leukemic cells, paving the way to chronic inflammatory diseases and to cancer resurgence, respectively. In both cases, a sexual dimorphism was measured in GSK3β-dependent cellular functions. GSK3β activity is a key marker for inflammatory and cancer diseases allowing adjusted therapy to sex, age and metabolic status of patients.


2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Ronald Pethig ◽  
Anoop Menachery ◽  
Steve Pells ◽  
Paul De Sousa

Dielectrophoresis can discriminate distinct cellular identities in heterogeneous populations, and monitor cell state changes associated with activation and clonal expansion, apoptosis, and necrosis, without the need for biochemical labels. Demonstrated capabilities include the enrichment of haematopoetic stem cells from bone marrow and peripheral blood, and adult stem cells from adipose tissue. Recent research suggests that this technique can predict the ultimate fate of neural stem cells after differentiationbeforethe appearance of specific cell-surface proteins. This review summarises the properties of cells that contribute to their dielectrophoretic behaviour, and their relevance to stem cell research and translational applications.


2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Nathan Moore ◽  
Stephen Lyle

Long-lived cancer stem cells (CSCs) with indefinite proliferative potential have been identified in multiple epithelial cancer types. These cells are likely derived from transformed adult stem cells and are thought to share many characteristics with their parental population, including a quiescent slow-cycling phenotype. Various label-retaining techniques have been used to identify normal slow cycling adult stem cell populations and offer a unique methodology to functionally identify and isolate cancer stem cells. The quiescent nature of CSCs represents an inherent mechanism that at least partially explains chemotherapy resistance and recurrence in posttherapy cancer patients. Isolating and understanding the cell cycle regulatory mechanisms of quiescent cancer cells will be a key component to creation of future therapies that better target CSCs and totally eradicate tumors. Here we review the evidence for quiescent CSC populations and explore potential cell cycle regulators that may serve as future targets for elimination of these cells.


2007 ◽  
Vol 16 (8) ◽  
pp. 867-873 ◽  
Author(s):  
David J. Eve ◽  
Paul R. Sanberg

One of the fastest growing fields in researching treatments for neurodegenerative and other disorders is the use of stem cells. These cells are naturally occurring and can be obtained from three different stages of an organism's life: embryonic, fetal, and adult. In the US, political doctrine has restricted use of federal funds for stem cells, enhancing research towards an adult source. In order to determine how this legislation may be represented by the stem cell field, a retrospective analysis of stem cell articles published in the journal Cell Transplantation over a 2-year period was performed. Cell Transplantation is considered a translational journal from preclinical to clinical, so it was of interest to determine the publication outcome of stem cell articles 6 years after the US regulations. The distribution of the source of stem cells was found to be biased towards the adult stage, but relatively similar over the embryonic and fetal stages. The fetal stem cell reports were primarily neural in origin, whereas the adult stem cell ones were predominantly mesenchymal and used mainly in neural studies. The majority of stem cell studies published in Cell Transplantation were found to fall under the umbrella of neuroscience research. American scientists published the most articles using stem cells with a bias towards adult stem cells, supporting the effect of the legislation, whereas Europe was the leading continent with a bias towards embryonic and fetal stem cells, where research is “controlled” but not restricted. Japan was also a major player in the use of stem cells. Allogeneic transplants (where donor and recipient are the same species) were the most common transplants recorded, although the transplantation of human-derived stem cells into rodents was the most common specific transplantation performed. This demonstrates that the use of stem cells is an increasingly important field (with a doubling of papers between 2005 and 2006), which is likely to develop into a major therapeutic area over the next few decades and that funding restrictions can affect the type of research being performed.


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