Pink1 and Parkin regulate Drosophila intestinal stem cell proliferation during stress and aging

Intestinal stem cells (ISCs) maintain the midgut epithelium in Drosophila melanogaster. Proper cellular turnover and tissue function rely on tightly regulated rates of ISC division and appropriate differentiation of daughter cells. However, aging and epithelial injury cause elevated ISC proliferation and decreased capacity for terminal differentiation of daughter enteroblasts (EBs). The mechanisms causing functional decline of stem cells with age remain elusive; however, recent findings suggest that stem cell metabolism plays an important role in the regulation of stem cell activity. Here, we investigate how alterations in mitochondrial homeostasis modulate stem cell behavior in vivo via RNA interference–mediated knockdown of factors involved in mitochondrial dynamics. ISC/EB-specific knockdown of the mitophagy-related genes Pink1 or Parkin suppresses the age-related loss of tissue homeostasis, despite dramatic changes in mitochondrial ultrastructure and mitochondrial damage in ISCs/EBs. Maintenance of tissue homeostasis upon reduction of Pink1 or Parkin appears to result from reduction of age- and stress-induced ISC proliferation, in part, through induction of ISC senescence. Our results indicate an uncoupling of cellular, tissue, and organismal aging through inhibition of ISC proliferation and provide insight into strategies used by stem cells to maintain tissue homeostasis despite severe damage to organelles.

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Macrophage modulation of dental pulp stem cell activity during tertiary dentinogenesis

Scientific Reports ◽

10.1038/s41598-020-77161-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Vitor C. M. Neves ◽

Val Yianni ◽

Paul T. Sharpe

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Immune Cells ◽

Dental Pulp ◽

Cell Activation ◽

Cell Activity ◽

Stem Cell Differentiation ◽

Dental Pulp Stem Cell ◽

Anti Inflammatory

AbstractThe interaction between immune cells and stem cells is important during tissue repair. Macrophages have been described as being crucial for limb regeneration and in certain circumstances have been shown to affect stem cell differentiation in vivo. Dentine is susceptible to damage as a result of caries, pulp infection and inflammation all of which are major problems in tooth restoration. Characterising the interplay between immune cells and stem cells is crucial to understand how to improve natural repair mechanisms. In this study, we used an in vivo damage model, associated with a macrophage and neutrophil depletion model to investigate the role of immune cells in reparative dentine formation. In addition, we investigated the effect of elevating the Wnt/β-catenin pathway to understand how this might regulate macrophages and impact upon Wnt receiving pulp stem cells during repair. Our results show that macrophages are required for dental pulp stem cell activation and appropriate reparative dentine formation. In addition, pharmacological stimulation of the Wnt/β-catenin pathway via GSK-3β inhibitor small molecules polarises macrophages to an anti-inflammatory state faster than inert calcium silicate-based materials thereby accelerating stem cell activation and repair. Wnt/β-catenin signalling thus has a dual role in promoting reparative dentine formation by activating pulp stem cells and promoting an anti-inflammatory macrophage response.

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Mitochondrial Dynamics in the Drosophila Ovary Regulates Germ Stem Cell Number, Cell Fate, and Female Fertility

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.596819 ◽

2021 ◽

Vol 8 ◽

Author(s):

Marcia Garcez ◽

Joana Branco-Santos ◽

Patricia C. Gracio ◽

Catarina C. F. Homem

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cell Fate ◽

Mitochondrial Dynamics ◽

Tricarboxylic Acid Cycle ◽

Cell Metabolism ◽

Cell Number ◽

Female Fertility ◽

Mitochondrial Activity ◽

Drosophila Ovary

The fate and proliferative capacity of stem cells have been shown to strongly depend on their metabolic state. Mitochondria are the powerhouses of the cell being responsible for energy production via oxidative phosphorylation (OxPhos) as well as for several other metabolic pathways. Mitochondrial activity strongly depends on their structural organization, with their size and shape being regulated by mitochondrial fusion and fission, a process known as mitochondrial dynamics. However, the significance of mitochondrial dynamics in the regulation of stem cell metabolism and fate remains elusive. Here, we characterize the role of mitochondria morphology in female germ stem cells (GSCs) and in their more differentiated lineage. Mitochondria are particularly important in the female GSC lineage. Not only do they provide these cells with their energy requirements to generate the oocyte but they are also the only mitochondria pool to be inherited by the offspring. We show that the undifferentiated GSCs predominantly have fissed mitochondria, whereas more differentiated germ cells have more fused mitochondria. By reducing the levels of mitochondrial dynamics regulators, we show that both fused and fissed mitochondria are required for the maintenance of a stable GSC pool. Surprisingly, we found that disrupting mitochondrial dynamics in the germline also strongly affects nurse cells morphology, impairing egg chamber development and female fertility. Interestingly, reducing the levels of key enzymes in the Tricarboxylic Acid Cycle (TCA), known to cause OxPhos reduction, also affects GSC number. This defect in GSC self-renewal capacity indicates that at least basal levels of TCA/OxPhos are required in GSCs. Our findings show that mitochondrial dynamics is essential for female GSC maintenance and female fertility, and that mitochondria fusion and fission events are dynamically regulated during GSC differentiation, possibly to modulate their metabolic profile.

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Fibroblast Growth Factors Regulate Stem Cell Functioning In Vitro and in Vivo.

Blood ◽

10.1182/blood.v104.11.1705.1705 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1705-1705

Author(s):

Joyce S.G Yeoh ◽

Ronald van Os ◽

Ellen Weersing ◽

Bert Dontje ◽

Edo Vellenga ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Growth Factors ◽

Cultured Cells ◽

Cell Activity ◽

Fibroblast Growth Factors ◽

Fibroblast Growth ◽

Stem Cell Activity

Abstract Fibroblast Growth Factors (FGF) are a large family of signaling molecules widely involved in tissue development, maintenance and repair. Little is known about the role of FGF/FGF-receptor signaling in the regulation of adult hematopoietic stem cells (HSC). In this study, we assessed the potential of exogenously added FGF-1/2, or retrovirally overexpressed FGF-1 to preserve HSC function in vitro and in vivo. First, we demonstrate that in vitro culture of unfractionated mouse bone marrow cells, in serum-free medium, supplemented with FGF-1 or FGF-2 or FGF-1 + 2 resulted in the robust generation of long-term repopulating (LTR) HSCs. Cultures were maintained for 12 weeks and during that time in vivo competitive reconstitution assays were performed. Stem cell activity was detectable at 3, 5, and 8 weeks after initiation of culture, but lost after 12 weeks. However, whereas 3 and 5 week cultured cells provided radioprotection in non-competitive assays, animals transplanted with 8 or 12 week cultured cells succumbed due to bone marrow failure. So far, we have been unable to expand single, highly purified Lin−Sca-1+c-Kit+ using FGF-1 + 2. Consequently, we speculated that essential intermediate cell populations or signals are required for FGF-induced stem cell conservation. To test this we cultured highly purified CD45.1 Lin−Sca-1+c-Kit+ cells in a co-culture with CD45.2 unfractionated BM. Co-cultured cells were transplanted after 5 weeks in lethally irradiated recipients, and CD45.1 chimerism levels were assessed. High levels of CD45.1 chimerism confirmed that Lin−Sca-1+c-Kit+ cells require an accessory signal in addition to FGF to induced stem cell activity in vitro. We subsequently tested stem cell potential of cells cultured in FGF-1 + 2 for 5 weeks, with the addition of SCF + IL-11 + Flt3L for the last 2, 4 or 7 days. Cell numbers increased with increasing time of growth factor presence. However, only when growth factors were present for 2 days engraftment of cultured cells in a competitive repopulation assay was increased 3.5-fold. Finally, we show by immunohistochemistry that ~10% of freshly isolated Lin−Sca-1+c-Kit+ expresses high levels of FGF-1. Retroviral overexpression of FGF-1 in stem cells resulted in increased growth potential and sustained clonogenic activity in vitro. Upon transplantation of transduced stem cells, FGF-1 overexpression resulted in increased white blood cell counts 4 weeks post-transplant compared to control animals. Most notable was a marked granulocytosis in FGF-1 overexpressing recipients Our results reveal FGF as an important regulator of HSC signaling and homeostasis. Importantly, in the presence of FGF stem cells can be maintained in vitro for 2 months. These findings open novel avenues for in vitro manipulation of stem cells for future clinical therapies.

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Committed T lymphocyte stem cells of rats. Characterization by surface W3/13 antigen and radiosensitivity.

Journal of Experimental Medicine ◽

10.1084/jem.154.4.1164 ◽

1981 ◽

Vol 154 (4) ◽

pp. 1164-1177 ◽

Cited By ~ 26

Author(s):

M J Dyer ◽

S V Hunt

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

T Cell ◽

Gamma Irradiation ◽

Bone Marrow Cells ◽

Fetal Liver ◽

Cell Activity ◽

Rat Bone

The existence of stem cells committed to the T lymphoid lineage was deduced from studying how rat T and B stem cells differ in their expression of membrane W3/13 antigen and in their susceptibility in vivo to gamma irradiation. Stem cell activity of rat bone marrow and fetal liver was measured in long-term radiation chimeras using B and T cell alloantigenic surface markers to identify the progeny of donor cells. Monoclonal mouse anti-rat thymocyte antibody W3/13 labeled approximately 40% of fetal liver cells and 60-70% of young rat bone marrow cells (40% brightly, 25% dimly). Bright, dim, and negative cells were separated on a fluorescence-activated cell sorter. All B and T lymphoid stem cells in fetal liver were W3/13 bright, as were B lymphoid stem cells in bone marrow. W3/13 dim bone marrow had over half the T cell repopulating activity of unseparated marrow but gave virtually no B cell repopulation. In further experiments, the radiosensitivity of endogenous B and T lymphoid stem cells was determined by exposing host rats to between 4.5 and 10 Gy of gamma irradiation before repopulation with genetically marked marrow. The results depended on whether chimerism was assayed before day 50 or after day 100. At early times, a radioresistant T stem cell was indicated, whose activity waned later. Thus committed T stem cells of rats carry moderate amounts of W3/13 antigen and are more radioresistant but less permanently chimeragenic than the stem cells that regenerate B lymphocytes.

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Ageing affects DNA methylation drift and transcriptional cell-to-cell variability in muscle stem cells

10.1101/500900 ◽

2018 ◽

Cited By ~ 1

Author(s):

Irene Hernando-Herraez ◽

Brendan Evano ◽

Thomas Stubbs ◽

Pierre-Henri Commere ◽

Stephen Clark ◽

...

Keyword(s):

Dna Methylation ◽

Stem Cells ◽

Stem Cell ◽

Functional Decline ◽

Cell Number ◽

Transcriptional Networks ◽

Mouse Muscle ◽

Muscle Stem Cells ◽

Age Related ◽

Cell To Cell Variability

Age-related tissue alterations have been associated with a decline in stem cell number and function. Although increased cell-to-cell variability in transcription or epigenetic marks has been proposed to be a major hallmark of ageing, little is known about the molecular diversity of stem cells during ageing. Here, by combined single-cell transcriptome and DNA methylome profiling in mouse muscle stem cells, we show a striking global increase of uncoordinated transcriptional heterogeneity together with context-dependent alterations of DNA methylation with age. Importantly, promoters with increased methylation heterogeneity are associated with increased transcriptional heterogeneity of the genes they drive. Notably, old cells that change the most with age reveal alterations in the transcription of genes regulating cell-niche interactions. These results indicate that epigenetic drift, by accumulation of stochastic DNA methylation changes in promoters, is a substantial driver of the degradation of coherent transcriptional networks with consequent stem cell functional decline during ageing.

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The role of translationally controlled tumor protein in proliferation ofDrosophilaintestinal stem cells

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1910850116 ◽

2019 ◽

Vol 116 (52) ◽

pp. 26591-26598 ◽

Cited By ~ 2

Author(s):

Young V. Kwon ◽

Bingqing Zhao ◽

Chiwei Xu ◽

Jiae Lee ◽

Chiao-Lin Chen ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Signaling Pathways ◽

Hippo Pathway ◽

Tissue Homeostasis ◽

Translationally Controlled Tumor Protein ◽

Cellular Processes ◽

The Hippo Pathway

Translationally controlled tumor protein (TCTP) is a highly conserved protein functioning in multiple cellular processes, ranging from growth to immune responses. To explore the role of TCTP in tissue maintenance and regeneration, we employed the adultDrosophilamidgut, where multiple signaling pathways interact to precisely regulate stem cell division for tissue homeostasis. Tctp levels were significantly increased in stem cells and enteroblasts upon tissue damage or activation of the Hippo pathway that promotes regeneration of intestinal epithelium. Stem cells with reduced Tctp levels failed to proliferate during normal tissue homeostasis and regeneration. Mechanistically, Tctp forms a complex with multiple proteins involved in translation and genetically interacts with ribosomal subunits. In addition, Tctp increases both Akt1 protein abundance and phosphorylation in vivo. Altogether, Tctp regulates stem cell proliferation by interacting with key growth regulatory signaling pathways and the translation process in vivo.

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P11.46 Discovery of a new HDAC6 inhibitor for the treatment of glioblastoma

Neuro-Oncology ◽

10.1093/neuonc/noz126.192 ◽

2019 ◽

Vol 21 (Supplement_3) ◽

pp. iii53-iii54

Author(s):

J Auzmendi-Iriarte ◽

A Saenz-Antoñanzas ◽

J Andermatten ◽

A Elua-Pinin ◽

E Aldaba ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cell Activity ◽

Selective Inhibitor ◽

Glioma Stem Cells ◽

Glioma Stem Cell ◽

In Vitro Activity ◽

Stem Cell Activity

Abstract BACKGROUND Glioblastoma’s origin and development is not only associated to genetic alterations, but also to epigenetic changes. Indeed, an altered expression or activity of epigenetic enzymes such as histone deacetylases (HDAC) has been associated to cancer stem cell activity, which has been widely described as a major feature for therapy resistance and tumor recurrence. In particular, inhibition of HDAC6 is an increasingly attractive pharmacological strategy, due to its association with low toxicity. Thus, the aim of the present study was to determine the impact of a new HDAC6-selective-inhibitor in glioblastoma and glioma stem cells. MATERIAL AND METHODS To test the effect of QTX compound in glioblastoma and glioma stem cell lines, cell viability after 72h of treatment was studied by MTT assay. After evaluation of IC50, QTX in vitro activity was analyzed, focusing on proliferation, apoptosis and stemness of U87-MG cell line and confirmed in a patient-derived glioma stem cell line. In vivo antitumor effect was evaluated using U87-MG cells xenografted in immunocompromised mice; after tumor formation, 5 mice were randomly selected as control group and another 5 for QTX treatment (intraperitoneal administration of 50 mg/kg; 5 days of dosing / 2 days off for 2 weeks). Mice weight was measured daily and tumor volume every two days. RESULTS We demonstrated that QTX reduces viability of all tested glioblastoma cells, even more greatly than normal astrocytes. Indeed, QTX diminishes proliferation and induces apoptosis in both conventional and patient-derived glioma cell lines. In particular, this effect was accompanied by a reduction of self-renewal properties of glioma stem cells. Interestingly, QTX in vitro activity was more effective comparing to the pan-inhibitor SAHA or the HDAC6-selective inhibitor Tubastatin A. Furthermore, QTX delayed tumor initiation and progression in vivo, without presenting significant side effects. CONCLUSION QTX compound presents a promising anti-tumor effect both in vitro and in vivo in glioblastoma, at least in part, inhibiting glioma stem cell activity.

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Age-related changes in Polycomb gene regulation disrupt lineage fidelity in intestinal stem cells

eLife ◽

10.7554/elife.62250 ◽

2021 ◽

Vol 10 ◽

Author(s):

Helen M Tauc ◽

Imilce A Rodriguez-Fernandez ◽

Jason A Hackney ◽

Michal Pawlak ◽

Tal Ronnen Oron ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Tissue Homeostasis ◽

Intestinal Stem Cells ◽

Chromatin Regulation ◽

Somatic Stem Cells ◽

Cell Specification ◽

Age Related ◽

The Impact ◽

Age Related Changes

Tissue homeostasis requires long-term lineage fidelity of somatic stem cells. Whether and how age-related changes in somatic stem cells impact the faithful execution of lineage decisions remains largely unknown. Here, we address this question using genome-wide chromatin accessibility and transcriptome analysis as well as single cell RNA-seq to explore stem cell-intrinsic changes in the aging Drosophila intestine. These studies indicate that in stem cells of old flies, promoters of Polycomb (Pc) target genes become differentially accessible, resulting in the increased expression of enteroendocrine (EE) cell specification genes. Consistently, we find age-related changes in the composition of the EE progenitor cell population in aging intestines, as well as a significant increase in the proportion of EE-specified intestinal stem cells (ISCs) and progenitors in aging flies. We further confirm that Pc-mediated chromatin regulation is a critical determinant of EE cell specification in the Drosophila intestine. Pc is required to maintain expression of stem cell genes while ensuring repression of differentiation and specification genes. Our results identify Pc group proteins as central regulators of lineage identity in the intestinal epithelium and highlight the impact of age-related decline in chromatin regulation on tissue homeostasis.

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Transcriptional reprogramming of skeletal muscle stem cells by the niche environment

10.21203/rs.3.rs-622329/v1 ◽

2021 ◽

Author(s):

Vahab Soleimani ◽

Felicia Lazure ◽

Rick Farouni ◽

Korin Sahinyan ◽

Darren Blackburn ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Tissue Regeneration ◽

Adult Stem Cells ◽

Cell Function ◽

Critical Role ◽

Negative Consequences ◽

Muscle Stem Cells ◽

Age Related

Abstract Adult stem cells are indispensable for tissue regeneration, but the number and regenerative capacity of stem cells declines with age. Whether the decrease in stem cell function is the cause or consequence of the aging of a tissue is unclear. Evidence suggests that the niche environment plays a critical role in the regulation of adult stem cell function6-10. However, quantification of the niche effect on stem cell function is an unmet challenge. Using muscle stem cells (MuSCs) as a model, we show that aging leads to a significant transcriptomic shift in MuSC subpopulations. By combining in vivo MuSC transplantation, multi-omics and computational methods, we show that the expression of approximately half of all age-altered genes in MuSCs can be restored by exposure to a young niche environment. Age-related genes whose expression is not restored exhibit altered chromatin accessibility and are associated with differentially methylated regions between young and aged cells. Our findings establish that the expression of the majority of age-related altered genes that are not epigenetically encoded is readily restorable by exposure to a young niche environment. The stem cell niche may therefore be an important therapeutic target to mitigate the negative consequences of aging on tissue regeneration.

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Age-Related Changes in Tissue-Specific Stem Cells.

Blood ◽

10.1182/blood.v112.11.sci-3.sci-3 ◽

2008 ◽

Vol 112 (11) ◽

pp. sci-3-sci-3

Author(s):

Amy J. Wagers ◽

Massimiliano Cerletti ◽

Shane R. Mayack ◽

Francis S. Kim ◽

Jennifer L. Shadrach

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cell Function ◽

Bone Marrow Failure ◽

Cell Activity ◽

Older Individuals ◽

Extrinsic Factors ◽

Tissue Specific ◽

Age Related ◽

Tissue Specific Stem Cells

Abstract Aging of multicellular organisms typically involves progressive decline in the body’s ability to maintain homeostatic cell replacement and to regenerate tissues and organs after injury. In both the blood and the skeletal muscle, aging significantly impairs regenerative activity and can dysregulate normal homeostatic production of mature cells. These age-acquired defects in tissue function profoundly impact the health of older individuals, as evidenced by the high incidence of age-related muscle deterioration (sarcopenia), bone marrow failure, immune dysfunction, and blood cancers in the elderly. How aging causes deterioration of tissue function is poorly understood, but several lines of evidence suggest that loss or functional impairment of tissue-specific stem cells directly contributes to age-dependent failures in tissue repair. Interestingly, the effects of aging on tissue stem cell function appear to arise at least in part from alterations in the aged tissue environment, which can inhibit stem cell activity in older animals and may be regulated by factors that circulate naturally in the bloodstream. By making use of sensitive in vivo and in vitro approaches, including direct cell isolation by FACS, we are investigating the extrinsic factors and interactions that control stem cell function in aged animals. Our current studies have pointed us toward a discrete set of metabolic regulators and inflammatory cytokines, which may alter the signals that stem cells receive from their environment in aged animals. The knowledge we gain from these ongoing studies will help to define novel strategies to delay or reverse the onset of age-related disease, extending the healthful life of aging individuals.

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