scholarly journals Gradual segregation of Adult Stem Cells and Niche cells during development from common precursors under the guidance of graded extracellular signals

2020 ◽  
Author(s):  
Amy Reilein ◽  
Helen V. Kogan ◽  
Rachel Misner ◽  
Karen Sophia Park ◽  
Daniel Kalderon
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Wnt Signaling ◽  
Cell Function ◽  
Adult Stem Cell ◽  
Follicle Cells ◽  
Pupal Development ◽  
Pathway Activity ◽  
Extracellular Signals ◽  
Egg Chambers

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.

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

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
David Melamed ◽  
Daniel Kalderon
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Wnt Pathway ◽  
Adult Stem Cell ◽  
Follicle Cells ◽  
Pathway Activity ◽  
Stem Cell Division ◽  
Follicle Stem Cells ◽  
Stat Pathway

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.

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
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Adult Stem Cells ◽  
Wnt Pathway ◽  
Opposite Polarity ◽  
Follicle Cells ◽  
Pathway Activity ◽  
Stat Signaling ◽  
Stat Pathway

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.

scholarly journals Aldehyde dehydrogenase 1a1 is dispensable for stem cell function in the mouse hematopoietic and nervous systems

Blood ◽  
2009 ◽  
Vol 113 (8) ◽  
pp. 1670-1680 ◽  
Author(s):  
Boaz P. Levi ◽  
Ömer H. Yilmaz ◽  
Gregg Duester ◽  
Sean J. Morrison
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Aldehyde Dehydrogenase ◽  
Cell Function ◽  
Hematopoietic Cells ◽  
Adult Stem Cell ◽  
Aldh Activity ◽  
Hematopoietic Stem ◽  
Nervous Systems ◽  
Adult Mice

Abstract High levels of aldehyde dehydrogenase (ALDH) activity have been proposed to be a common feature of stem cells. Adult hematopoietic, neural, and cancer stem cells have all been reported to have high ALDH activity, detected using Aldefluor, a fluorogenic substrate for ALDH. This activity has been attributed to Aldh1a1, an enzyme that is expressed at high levels in stem cells and that has been suggested to regulate stem cell function. Nonetheless, Aldh1a1 function in stem cells has never been tested genetically. We observed that Aldh1a1 was preferentially expressed in mouse hematopoietic stem cells (HSCs) and expression increased with age. Hematopoietic cells from Aldh1a1-deficient mice exhibited increased sensitivity to cyclophosphamide in a non–cell-autonomous manner, consistent with its role in cyclophosphamide metabolism in the liver. However, Aldh1a1 deficiency did not affect hematopoiesis, HSC function, or the capacity to reconstitute irradiated recipients in young or old adult mice. Aldh1a1 deficiency also did not affect Aldefluor staining of hematopoietic cells. Finally, Aldh1a1 deficiency did not affect the function of stem cells from the adult central or peripheral nervous systems. Aldh1a1 is not a critical regulator of adult stem cell function or Aldefluor staining in mice.

scholarly journals An ancient Pygo-dependent Wnt enhanceosome integrated by Chip/LDB-SSDP

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Marc Fiedler ◽  
Michael Graeb ◽  
Juliusz Mieszczanek ◽  
Trevor J Rutherford ◽  
Christopher M Johnson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Embryonic Development ◽  
Wnt Signaling ◽  
Binding Proteins ◽  
Adult Stem Cell ◽  
Previous Evidence ◽  
Cell Compartments ◽  
Nuclear Factors ◽  
Proteomics Approach

TCF/LEF factors are ancient context-dependent enhancer-binding proteins that are activated by β-catenin following Wnt signaling. They control embryonic development and adult stem cell compartments, and their dysregulation often causes cancer. β-catenin-dependent transcription relies on the NPF motif of Pygo proteins. Here, we use a proteomics approach to discover the Chip/LDB-SSDP (ChiLS) complex as the ligand specifically binding to NPF. ChiLS also recognizes NPF motifs in other nuclear factors including Runt/RUNX2 and Drosophila ARID1, and binds to Groucho/TLE. Studies of Wnt-responsive dTCF enhancers in the Drosophila embryonic midgut indicate how these factors interact to form the Wnt enhanceosome, primed for Wnt responses by Pygo. Together with previous evidence, our study indicates that ChiLS confers context-dependence on TCF/LEF by integrating multiple inputs from lineage and signal-responsive factors, including enhanceosome switch-off by Notch. Its pivotal function in embryos and stem cells explain why its integrity is crucial in the avoidance of cancer.

Stem Cell Function, Self-Renewal, Heterogeneity, and Regenerative Potential in Skeletal Muscle Stem Cells

2012 ◽  
Vol 2 (1) ◽  
pp. 11-21
Author(s):  
Silvia Cristini ◽  
Giulio Alessandri ◽  
Francesco Acerbi ◽  
Daniela Tavian ◽  
Eugenio A. Parati ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Cell Function ◽  
Self Renewal ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

Stem Cell Function, Self-Renewal, Heterogeneity, and Regenerative Potential in Skeletal Muscle Stem Cells

2012 ◽  
Vol 2 (1) ◽  
pp. 11-21
Author(s):  
Silvia Cristini ◽  
Giulio Alessandri ◽  
Francesco Acerbi ◽  
Daniela Tavian ◽  
Eugenio A. Parati ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Cell Function ◽  
Self Renewal ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

scholarly journals Multiple Roles for Cholinergic Signaling from the Perspective of Stem Cell Function

2021 ◽  
Vol 22 (2) ◽  
pp. 666
Author(s):  
Toshio Takahashi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Function ◽  
Cell Activity ◽  
Embryonic Stem ◽  
Cholinergic Neurons ◽  
Cell Types ◽  
Proliferative Potential ◽  
True Nature ◽  
Cholinergic Signaling

Stem cells have extensive proliferative potential and the ability to differentiate into one or more mature cell types. The mechanisms by which stem cells accomplish self-renewal provide fundamental insight into the origin and design of multicellular organisms. These pathways allow the repair of damage and extend organismal life beyond that of component cells, and they probably preceded the evolution of complex metazoans. Understanding the true nature of stem cells can only come from discovering how they are regulated. The concept that stem cells are controlled by particular microenvironments, also known as niches, has been widely accepted. Technical advances now allow characterization of the zones that maintain and control stem cell activity in several organs, including the brain, skin, and gut. Cholinergic neurons release acetylcholine (ACh) that mediates chemical transmission via ACh receptors such as nicotinic and muscarinic receptors. Although the cholinergic system is composed of organized nerve cells, the system is also involved in mammalian non-neuronal cells, including stem cells, embryonic stem cells, epithelial cells, and endothelial cells. Thus, cholinergic signaling plays a pivotal role in controlling their behaviors. Studies regarding this signal are beginning to unify our understanding of stem cell regulation at the cellular and molecular levels, and they are expected to advance efforts to control stem cells therapeutically. The present article reviews recent findings about cholinergic signaling that is essential to control stem cell function in a cholinergic niche.

scholarly journals Empowering Muscle Stem Cells for the Treatment of Duchenne Muscular Dystrophy

2021 ◽  
pp. 1-14
Author(s):  
Romina L. Filippelli ◽  
Natasha C. Chang
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Cell Function ◽  
Critical Role ◽  
Membrane Integrity ◽  
Muscle Membrane ◽  
Muscle Stem Cell ◽  
Muscle Stem Cells

Duchenne muscular dystrophy (DMD) is a devastating and debilitating muscle degenerative disease affecting 1 in every 3,500 male births worldwide. DMD is progressive and fatal; accumulated weakening of the muscle tissue leads to an inability to walk and eventual loss of life due to respiratory and cardiac failure. Importantly, there remains no effective cure for DMD. DMD is caused by defective expression of the <i>DMD</i> gene, which encodes for dystrophin, a component of the dystrophin glycoprotein complex. In muscle fibers, this protein complex plays a critical role in maintaining muscle membrane integrity. Emerging studies have shown that muscle stem cells, which are adult stem cells responsible for muscle repair, are also affected in DMD. DMD muscle stem cells do not function as healthy muscle stem cells, and their impairment contributes to disease progression. Deficiencies in muscle stem cell function include impaired establishment of cell polarity leading to defective asymmetric stem cell division, reduced myogenic commitment, impaired differentiation, altered metabolism, and enhanced entry into senescence. Altogether, these findings indicate that DMD muscle stem cells are dysfunctional and have impaired regenerative potential. Although recent advances in adeno-associated vector and antisense oligonucleotide-mediated mechanisms for gene therapy have shown clinical promise, the current therapeutic strategies for muscular dystrophy do not effectively target muscle stem cells and do not address the deficiencies in muscle stem cell function. Here, we discuss the merits of restoring endogenous muscle stem cell function in degenerating muscle as a viable regenerative medicine strategy to mitigate DMD.

scholarly journals GSK3β, a Master Kinase in the Regulation of Adult Stem Cell Behavior

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Claire Racaud-Sultan ◽  
Nathalie Vergnolle
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Adult Stem Cells ◽  
Glycogen Synthase ◽  
Inflammatory Diseases ◽  
Adult Stem Cell ◽  
Leukemic Cells ◽  
Cell Phenotype ◽  
Epithelial Regeneration ◽  
Cell Functions

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.

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