scholarly journals PIWI-piRNA pathway-mediated transposable element repression in Hydra somatic stem cells

2019 ◽  
Author(s):  
Bryan B. Teefy ◽  
Stefan Siebert ◽  
Jack F. Cazet ◽  
Haifan Lin ◽  
Celina E. Juliano
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cells ◽  
Mammalian Cells ◽  
Cell Types ◽  
Somatic Tissue ◽  
Epithelial Stem Cells ◽  
Conserved Sequence ◽  
Rna Immunoprecipitation ◽  
Pirna Pathway

AbstractTransposable elements (TEs) can damage genomes, thus organisms employ a variety of mechanisms to repress TE expression. However, these mechanisms often fail over time leading to de-repression of TEs in aging tissues. The PIWI-piRNA pathway is a small RNA pathway that represses TE expression in the germline of animals. Here we explore the function of the pathway in the epithelial stem cells of Hydra, a long-lived freshwater cnidarian. Hydra have three stem cell populations; endodermal and ectodermal epithelial stem cells are strictly somatic, whereas the interstitial stem cells retain germline competence. In our previous study, we found that the PIWI proteins are expressed in all three Hydra stem cell types. In this study, we focus on the ectodermal and endodermal epithelial stem cells to understand the somatic function of the pathway. We isolated piRNAs from Hydra that lack the interstitial lineage and found that these somatic piRNAs map predominantly to TE transcripts and display the conserved sequence signatures typical of germline piRNAs. Three lines of evidence suggest that the PIWI-piRNA pathway represses TEs in Hydra epithelial stem cells. First, epithelial knockdown of the Hydra PIWI protein hywi resulted in upregulation of TE expression. Second, degradome sequencing revealed evidence of PIWI-mediated cleavage of TE RNAs in epithelial cells using the ping-pong mechanism. Finally, we demonstrated a direct association between Hywi protein and TE transcripts in epithelial cells using RNA immunoprecipitation. Interestingly, we found that RNAi knockdown of hywi leads to an upregulation of genes involved in innate immunity, which may be in response to TE upregulation; this is consistent with recent studies on TE expression in mammalian cells. Altogether, this study suggests a function for the PIWI-piRNA pathway in maintaining the long-lived somatic cell lineages of Hydra and may point to a broader role for this pathway in protecting somatic tissue from TE-induced damage.

scholarly journals Characterization of putative stem cells in isolated human colonic crypt epithelial cells and their interactions with myofibroblasts

2009 ◽  
Vol 296 (2) ◽  
pp. C296-C305 ◽  
Author(s):  
S. Samuel ◽  
R. Walsh ◽  
J. Webb ◽  
A. Robins ◽  
C. Potten ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cells ◽  
Side Population ◽  
Cell Types ◽  
Population Characteristics ◽  
Colonic Crypt ◽  
Epithelial Stem Cells ◽  
Colonic Crypts ◽  
Cell Niche

Colonic epithelial stem cells are believed to be located at the crypt base where they have previously been shown to express musashi-1. The colonic stem cell niche, which includes extracellular matrix and myofibroblasts (together with other cell types), is likely to be important in maintaining the function of the progenitor cells. The aims of our studies were to characterize stem cells in isolated and disaggregated human colonic crypt epithelial cells and investigate their interactions with monolayers of primary human colonic myofibroblasts. In unfractionated preparations of disaggregated colonic crypts, musashi-1 positive cells preferentially adhered to colonic myofibroblasts, despite the presence of excess blocking anti-β1-integrin antibody. These adherent epithelial cells remained viable for a number of days and developed slender processes. Cells with side population characteristics (as demonstrated by ability to expel the dye Hoechst 33342) were consistently seen in the isolated colonic crypt epithelial cells. These side population cells expressed musashi-1, β1-integrin, BerEP4, and CD133. Sorted side population crypt epithelial cells also rapidly adhered to primary colonic myofibroblasts. In conclusion, in preparation of isolated and disaggregated human colonic crypts, cells with stem cell characteristics preferentially adhere to primary human colonic myofibroblasts in a β1-integrin-independent fashion.

scholarly journals Islet morphogenesis and stem cell markers in rat pancreas.

1996 ◽  
Vol 44 (9) ◽  
pp. 947-951 ◽  
Author(s):  
L Bouwens ◽  
E De Blay
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cells ◽  
Endocrine Cells ◽  
Stem Cell Marker ◽  
Intermediate Filament Protein ◽  
Stem Cell Markers ◽  
Epithelial Stem Cells ◽  
Duct Cells ◽  
Pancreatic Islets Of Langerhans

During embryonic development, and possibly also later in life, pancreatic islets of Langerhans originate from differentiating epithelial stem cells. These stem cells are situated in the pancreatic ducts but are otherwise poorly characterized. We found by immunohistochemical staining that protodifferentiated pancreatic epithelial cells from rat embryos of Day 13-Day 15 express the cytoskeletal protein keratin 20, similar to mature duct epithelium. During the period of islet morphogenesis, which occurs between Day 17 and birth, large aggregates of K20-positive duct cells were formed, which gradually differentiated into endocrine cells. This islet morphogenic mechanism has not been described thus far and we did not observe it in postnatal rats. During fetal islet formation, transient expression of vimentin was noted in the duct cells but not in endocrine cells. This intermediate filament protein is not observed in duct epithelial cells after birth. The proto-oncogene product bcl-2, a putative epithelial stem cell marker, was detected in duct cells from fetal and postnatal pancreas. We conclude that K20, vimentin, and bcl-2 are markets for the pancreatic (islet) stem cells.

scholarly journals Comparative Analysis of KnockOut™Serum with Fetal Bovine Serum for the In Vitro Long-Term Culture of Human Limbal Epithelial Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Shaokun Zhang ◽  
Zaoxia Liu ◽  
Guanfang Su ◽  
Hong Wu
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Bovine Serum ◽  
Fetal Bovine Serum ◽  
Epithelial Stem Cells ◽  
Fetal Bovine ◽  
Limbal Epithelial Stem Cells

The limbal epithelial cells can be maintained on 3T3 feeder layer with fetal bovine serum supplemented culture medium, and these cells have been used to successfully treat limbal stem cell deficiency. However, fetal bovine serum contains unknown components and displays quantitative and qualitative lot-to-lot variations. To improve the culture condition, the defined KnockOut serum replacement was investigated to replace fetal bovine serum for culturing human limbal epithelial cell. Human primary limbal epithelial cells were cultured in KnockOut serum and fetal bovine serum supplemented medium, respectively. The cell growth rate, gene expression, and maintenance of limbal epithelial stem cells were studied and compared between these two groups. Human primary limbal epithelial cells were isolated and successfully serially cultivated in this novel KnockOut serum supplemented medium; the cell proliferation and stem cell maintenance were similar to those of cells grown in fetal bovine serum supplemented medium. These data suggests that this KnockOut serum supplemented medium is an efficient replacement to traditional fetal bovine serum supplemented medium for limbal epithelial cell culture, and this medium has great potential for long term maintenance of limbal epithelial cells, limbal epithelial stem cells transplantation, and tissue regeneration.

scholarly journals The role of pulmonary mesenchymal cells in airway epithelium regeneration during injury repair

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Suyun Fang ◽  
Suhong Zhang ◽  
Haiting Dai ◽  
Xiaoxiang Hu ◽  
Changgong Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Airway Epithelium ◽  
Cell Types ◽  
Mesenchymal Cells ◽  
Ciliated Cells ◽  
Epithelial Stem Cells ◽  
Injury Repair ◽  
Club Cells

Abstract Background The airways of mammalian lung are lined with highly specialized cell types that are the target of airborne toxicants and injury. Several epithelial cell types and bone marrow-derived mesenchymal stem cells have been identified to serve as stem cells during injury repair. However, the contributions of endogenous mesenchymal cells to recruitment, expansion or differentiation of stem cells, and repair and reestablishment of the normal composition of airway epithelium following injury have not been addressed. Methods The role of mouse pulmonary mesenchymal cells was investigated by lineage tracing using Dermo1-Cre; ROSAmTmG mice. In experimental models of lung injury by lipopolysaccharide and naphthalene, GFP-labeled Dermo1+ mesenchymal cells were traced during injury repair. In vitro lung explant culture treated with or without lipopolysaccharide was also used to verify in vivo data. Results During injury repair, a subgroup of GFP-labeled Dermo1+ mesenchymal cells were found to contribute to normal repair of the airway epithelium and differentiated into Club cells, ciliated cells, and goblet cells. In Club cell-specific naphthalene injury model, the process of Dermo1+ stem cell regenerating epithelial cells was dissected. The Dermo1+ stem cells was migrated into the airway epithelium layer sooner after injury, and sequentially differentiated transitionally to epithelial stem cells, such as neuroendocrine cells, and finally to newly differentiated Club cells, ciliated cells, and goblet cells in injury repair. Conclusion In this study, a population of Dermo1+ mesenchymal stem cell was identified to serve as stem cells in airway epithelial cell regeneration during injury repair. The Dermo1+ mesenchymal stem cell differentiated into epithelial stem cells before reestablishing various epithelial cells. These findings have implications for understanding the regulation of lung repair and the potential for usage of mesenchymal stem cells in therapeutic strategies for lung diseases.

scholarly journals Human Amniotic Epithelial Stem Cells: A Promising Seed Cell for Clinical Applications

2020 ◽  
Vol 21 (20) ◽  
pp. 7730
Author(s):  
Chen Qiu ◽  
Zhen Ge ◽  
Wenyu Cui ◽  
Luyang Yu ◽  
Jinying Li
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cellular Therapy ◽  
Therapeutic Potential ◽  
Current Knowledge ◽  
Embryonic Stem ◽  
Cell Types ◽  
Epithelial Stem Cells ◽  
Application Procedure ◽  
Cell Source

Perinatal stem cells have been regarded as an attractive and available cell source for medical research and clinical trials in recent years. Multiple stem cell types have been identified in the human placenta. Recent advances in knowledge on placental stem cells have revealed that human amniotic epithelial stem cells (hAESCs) have obvious advantages and can be used as a novel potential cell source for cellular therapy and clinical application. hAESCs are known to possess stem-cell-like plasticity, immune-privilege, and paracrine properties. In addition, non-tumorigenicity and a lack of ethical concerns are two major advantages compared with embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). All of the characteristics mentioned above and other additional advantages, including easy accessibility and a non-invasive application procedure, make hAESCs a potential ideal cell type for use in both research and regenerative medicine in the near future. This review article summarizes current knowledge on the characteristics, therapeutic potential, clinical advances and future challenges of hAESCs in detail.

scholarly journals Identification, Characterization, and Transcriptional Reprogramming of Epithelial Stem Cells and Intestinal Enteroids in Simian Immunodeficiency Virus Infected Rhesus Macaques

2021 ◽  
Vol 12 ◽  
Author(s):  
Nongthombam Boby ◽  
Xuewei Cao ◽  
Alyssa Ransom ◽  
Barcley T. Pace ◽  
Christopher Mabee ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Immune Activation ◽  
Molecular Mechanisms ◽  
Stem Cell Population ◽  
Epithelial Stem Cells ◽  
Epithelial Regeneration ◽  
Siv Infection

Epithelial cell injury and impaired epithelial regeneration are considered key features in HIV pathogenesis and contribute to HIV-induced generalized immune activation. Understanding the molecular mechanisms underlying the disrupted epithelial regeneration might provide an alternative approach for the treatment of HIV-mediated enteropathy and immune activation. We have observed a significant increased presence of α defensin5+ (HD5) Paneth cells and proliferating Ki67+ epithelial cells as well as decreased expression of E-cadherin expression in epithelial cells during SIV infection. SIV infection did not significantly influence the frequency of LGR5+ stem cells, but the frequency of HD5+ cells was significantly higher compared to uninfected controls in jejunum. Our global transcriptomics analysis of enteroids provided novel information about highly significant changes in several important pathways like metabolic, TCA cycle, and oxidative phosphorylation, where the majority of the differentially expressed genes were downregulated in enteroids grown from chronically SIV-infected macaques compared to the SIV-uninfected controls. Despite the lack of significant reduction in LGR5+ stem cell population, the dysregulation of several intestinal stem cell niche factors including Notch, mTOR, AMPK and Wnt pathways as well as persistence of inflammatory cytokines and chemokines and loss of epithelial barrier function in enteroids further supports that SIV infection impacts on epithelial cell proliferation and intestinal homeostasis.

Stem Cell Cure for Kidney Injury: Therapy to Solve Most Complex Issues in Renal System

2020 ◽  
Author(s):  
Prithiv K R Kumar
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Kidney Injury ◽  
Cell Types ◽  
Tissue Remodelling ◽  
Major Health Problem ◽  
In Vivo Experiments ◽  
Renal Regeneration ◽  
Induced Pluripotent

Renal failure is a major health problem. The mortality rate remain high despite of several therapies. The most complex of the renal issues are solved through stem cells. In this review, different mechanism for cure of chronic kidney injury along with cell engraftment incorporated into renal structures will be analysed. Paracrine activities of embryonic or induced Pluripotent stem cells are explored on the basis of stem cell-induced kidney regeneration. Several experiments have been conducted to advance stem cells to ensure the restoration of renal functions. More vigour and organised protocols for delivering stem cells is a possibility for advancement in treatment of renal disease. Also there is a need for pressing therapies to replicate the tissue remodelling and cellular repair processes suitable for renal organs. Stem cells are the undifferentiated cells that have the ability to multiply into several cell types. In vivo experiments on animal’s stem cells have shown significant improvements in the renal regeneration and functions of organs. Nevertheless more studies show several improvements in the kidney repair due to stem cell regeneration.

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 Stem Cells in the Path of Light, from Corneal to Retinal Reconstruction

Biomedicines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 873
Author(s):  
Ovidiu Samoila ◽  
Lacramioara Samoila
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Clinical Success ◽  
Corneal Stroma ◽  
Cell Transplant ◽  
Inclusion Criteria ◽  
Epithelial Stem Cells ◽  
Corneal Epithelial ◽  
Stem Cells Transplantation ◽  
Limbal Epithelial Stem Cells

The future of eye reconstruction invariably includes stem cells transplantation. Corneal limbus, corneal stroma, trabeculum, retinal cells, optic nerve, and all structures that are irreversibly damaged and have no means to be repaired or replaced, through conventional treatment or surgery, represent targets for stem cell reconstruction. This review tries to answer the question if there is any clinical validation for stem therapies, so far, starting from the cornea and, on the path of light, arriving to the retina. The investigation covers the last 10 years of publications. From 2385 published sources, we found 56 clinical studies matching inclusion criteria, 39 involving cornea, and 17 involving retina. So far, corneal epithelial reconstruction seems well validated clinically. Enough clinical data are collected to allow some form of standardization for the stem cell transplant procedures. Cultivated limbal epithelial stem cells (CLET), simple limbal epithelial transplant (SLET), and oral mucosa transplantation are implemented worldwide. In comparison, far less patients are investigated in retinal stem reconstructions, with lower anatomical and clinical success, so far. Intravitreal, subretinal, and suprachoroidal approach for retinal stem therapies face specific challenges.

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