Abstract 17305: The ER Unfolded Protein Response Effector, ATF6, Promotes Proliferation and Maintains Pluripotency in Cardiac Stem Cells

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Winston T Stauffer ◽  
Shirin Doroudgar ◽  
Haley N Stephens ◽  
Erik A Blackwood ◽  
Christopher C Glembotski
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Viability ◽  
Unfolded Protein Response ◽  
Cardiac Stem Cells ◽  
Antioxidant Gene ◽  
Unfolded Protein ◽  
Proliferation And Differentiation ◽  
Protein Response

Recent studies have suggested that multipotent stem cells residing in the adult heart, called cardiac stem cells (CSCs), mitigate damage in the infarcted or failing heart. Investigating the factors governing CSC proliferation and differentiation is key to understanding what role these cells play in the heart and in future therapeutic strategies. Additionally, activating transcription factor 6 (ATF6), an effector of the endoplasmic reticulum (ER) unfolded protein response (UPR), plays critical roles in development, as well as in the differentiation of certain stem cell types, though it has not been studied in this regard in the heart. Our lab has demonstrated that ATF6 in cardiac myocytes is cardioprotective in vivo during ischemia/reperfusion partly by virtue of its ability to induce an antioxidant gene program that reduces damaging reactive oxygen species (ROS). However, ATF6, and its involvement in antioxidant gene induction, have not been studied in CSCs. Therefore, here we hypothesized that activation of the ATF6 branch of the UPR in CSCs is important for their proliferation and differentiation, given that ROS is known to be essential for these processes. To address this hypothesis, we subjected cultured mouse CSCs to simulated ischemia and observed increased ATF6 target gene mRNA levels. This demonstrates that, despite their undifferentiated status, CSCs have a functional UPR, which can be activated in response to ischemic stress. ATF6 loss of function (LOF) in CSCs, via RNAi or chemical inhibitor, yielded a basal decrease in cell viability and an increase in several differentiation markers, similar to the effect of dexamethasone differentiation stimulus. Increased ROS was also observed in an ATF6 LOF model. Strikingly, cotreatment with a chemical ROS inhibitor significantly rescued cell viability and reduced markers of differentiation in CSCs with reduced ATF6 function. These results suggest that CSCs require a basal level of ATF6 activity to maintain their proliferation and pluripotentcy in vitro and that this is mediated by the role of ATF6 in the mitigation of ROS. This is an important finding given that stem cell expansion in vitro is a critical step in the characterization of stem cells and their use in many therapeutic treatment strategies.

scholarly journals TRiC activates the unfolded protein response and protects starved stem cells by modulating energy and lipid metabolism during planarian regeneration

2019 ◽  
Author(s):  
Óscar Gutiérrez-Gutiérrez ◽  
Daniel A. Felix ◽  
Alessandra Salvetti ◽  
Anne Thems ◽  
Stefan Pietsch ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Proliferation ◽  
Stem Cell ◽  
Lipid Metabolism ◽  
Unfolded Protein Response ◽  
Stem Cell Proliferation ◽  
Unfolded Protein ◽  
Cell Genome ◽  
The Unfolded Protein Response ◽  
Protein Response

SummaryFasting protects stem cells and increases stem cell functionality through mechanisms which are not fully understood. Planarians are not only able to regenerate their bodies, but also to stand long periods of starvation by shrinking in size. This adaptation is possible because of a large population of adult stem cells which indefinitely self-renew even under starved conditions and thus confer planarians with immortality. How starved planarians are able to maintain healthy stem cells and to fuel stem cell proliferation allowing regeneration is unknown. Here we found the TCP-1 ring complex (TRiC) to be upregulated in starved stem cells. Down-regulation of TRiC impairs planarian regenerative response by inducing stem cell genome instability, mitotic defects and stem cell death which translates into stem cell exhaustion. This regulation is specific of starvation since feeding planarians prevents the phenotype. Importantly we found that TRiC activates the unfolded protein response (UPR) which allows a convergent regulation of cellular energy and lipid metabolism in starved planarians thus permitting the high energy demanding regenerative mitotic response. We identified a novel mechanism through which starvation protects the somatic stem cell genome allowing for unlimited stem cell proliferation and regeneration.

Abstract 479: The ER Unfolded Protein Response Effector, ATF6, Promotes Proliferation and Maintains Pluripotency in Cardiac Stem Cells

2018 ◽  
Vol 123 (Suppl_1) ◽  
Author(s):  
Winston T Stauffer ◽  
Shirin Doroudgar ◽  
Hailey N Stephens ◽  
Erik A Blackwood ◽  
Christopher C Glembotski
Keyword(s):  
Stem Cells ◽  
Unfolded Protein Response ◽  
Cardiac Stem Cells ◽  
Unfolded Protein ◽  
Protein Response

scholarly journals USP19 deubiquitinating enzyme inhibits muscle cell differentiation by suppressing unfolded-protein response signaling

2015 ◽  
Vol 26 (5) ◽  
pp. 913-923 ◽  
Author(s):  
Benjamin Wiles ◽  
Miao Miao ◽  
Erin Coyne ◽  
Louise Larose ◽  
Andrey V. Cybulsky ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Unfolded Protein Response ◽  
Muscle Cell ◽  
Deubiquitinating Enzyme ◽  
Muscle Cell Differentiation ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

USP19 deubiquitinating enzyme has two isoforms, cytoplasmic and endoplasmic reticulum (ER) localized. The ER-localized isoform specifically suppresses muscle cell differentiation in vitro and appears to do so by inhibiting the unfolded-protein response that occurs during such differentiation. In vivo, loss of USP19 promotes muscle regeneration following injury.

scholarly journals Mitochondrial Activity and Unfolded Protein Response are Required for Neutrophil Differentiation

2018 ◽  
Vol 47 (5) ◽  
pp. 1936-1950 ◽  
Author(s):  
Ayako Tanimura ◽  
Keiko Miyoshi ◽  
Taigo Horiguchi ◽  
Hiroko Hagita ◽  
Koichi Fujisawa ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Morphological Differentiation ◽  
Hematopoietic Differentiation ◽  
Macrophage Differentiation ◽  
Mitochondrial Energy Metabolism ◽  
Unfolded Protein ◽  
Protein Response ◽  
Neutrophil Differentiation

Background/Aims: Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are involved in hematopoietic differentiation. However, the mechanistic linkage between ER stress/UPR and hematopoietic differentiation remains unclear. Methods: We used bipotent HL-60 cells as an in vitro hematopoietic differentiation system to investigate the role of ER stress and UPR activity in neutrophil and macrophage differentiation. Results: The in vitro differentiation analysis revealed that ER stress decreased during both neutrophil and macrophage differentiations, and the activities of PERK and ATF6 were decreased and that of IRE1α was increased during neutrophil differentiation in a stage-specific manner. By contrast, the activities of ATF6 and ATF4 decreased during macrophage differentiation. When the cells were treated with oligomycin, the expression of CD11b, a myelocytic differentiation marker, and morphological differentiation were suppressed, and XBP-1 activation was inhibited during neutrophil differentiation, whereas CD11b expression was maintained, and morphological differentiation was not obviously affected during macrophage differentiation. Conclusion: In this study, we demonstrated that neutrophil differentiation is regulated by ER stress/UPR that is supported by mitochondrial ATP supply, in which IRE1α-XBP1 activation is essential. Our findings provide the evidence that mitochondrial energy metabolism may play a critical role in neutrophil differentiation.

scholarly journals Targeting Glioblastoma Stem Cells with 2-Deoxy-D-Glucose (2-DG) Potentiates Radiation-Induced Unfolded Protein Response (UPR)

Cancers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 159 ◽  
Author(s):  
Sumedh Shah ◽  
Gregor Rodriguez ◽  
Alexis Musick ◽  
Winston Walters ◽  
Nicolas de Cordoba ◽  
...  
Keyword(s):  
Stem Cells ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Treatment Options ◽  
Disease Recurrence ◽  
Primary Brain Tumor ◽  
Internal Diameter ◽  
Unfolded Protein ◽  
Patient Database ◽  
Protein Response

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, and despite optimized treatment options, median survival remains dismal. Contemporary evidence suggests disease recurrence results from expansion of a robustly radioresistant subset of GBM progenitor cells, termed GBM stem cells (GSCs). In this study, we utilized transmission electron microscopy to uncover ultrastructural effects on patient-derived GSC lines exposed to supratherapeutic radiotherapy levels. Elevated autophagosome formation and increased endoplasmic reticulum (ER) internal diameter, a surrogate for ER stress and activation of unfolded protein response (UPR), was uncovered. These observations were confirmed via protein expression through Western blot. Upon interrogating genomic data from an open-access GBM patient database, overexpression of UPR-related chaperone protein genes was inversely correlated with patient survival. This indicated controlled UPR may play a role in promoting radioresistance. To determine if potentiating UPR further can induce apoptosis, we exposed GSCs to radiation with an ER stress-inducing drug, 2-deoxy-D-glucose (2-DG), and found dose-dependent decreases in viability and increased apoptotic marker expression. Taken together, our results indicate GSC radioresistance is, in part, achieved by overexpression and overactivation of ER stress-related pathways, and this effect can be overcome via potentiation of UPR, leading to loss of GSC viability.

scholarly journals Exogenous Therapeutics of Microrna-29a Attenuates Development of Hepatic Fibrosis in Cholestatic Animal Model through Regulation of Phosphoinositide 3-Kinase p85 Alpha

2020 ◽  
Vol 21 (10) ◽  
pp. 3636 ◽  
Author(s):  
Ya-Ling Yang ◽  
Feng-Sheng Wang ◽  
Hung-Yu Lin ◽  
Ying-Hsien Huang
Keyword(s):  
Liver Fibrosis ◽  
Unfolded Protein Response ◽  
Luciferase Reporter ◽  
Heat Shock Protein 60 ◽  
Unfolded Protein ◽  
Duct Ligation ◽  
Phosphoinositide 3 Kinase ◽  
Human Liver Cirrhosis ◽  
Protein Response

Recent studies have found that microRNA-29a (miR-29a) levels are significantly lower in fibrotic livers, as shown with human liver cirrhosis. Such downregulation influences the activation of hepatic stellate cells (HSC). Phosphoinositide 3-kinase p85 alpha (PI3KP85α) is implicated in the regulation of proteostasis mitochondrial integrity and unfolded protein response (UPR) and apoptosis in hepatocytes. This study aimed to investigate the potential therapeutic role of miR-29a in a murine bile duct ligation (BDL)-cholestatic injury and liver fibrosis model. Mice were assigned to four groups: sham, BDL, BDL + scramble miRs, and BDL + miR-29a-mimic. Liver fibrosis and inflammation were assessed by histological staining and mRNA/protein expression of representative markers. Exogenous therapeutics of miR-29a in BDL-stressed mice significantly attenuated glutamic oxaloacetic transaminase (GOT)/glutamic-pyruvic transaminase (GPT) and liver fibrosis, and caused a significant downregulation in markers related to inflammation (IL-1β), fibrogenesis (TGF-β1, α-SMA, and COL1α1), autophagy (p62 and LC3B II), mitochondrial unfolded protein response (UPRmt; C/EBP homologous protein (CHOP), heat shock protein 60 (HSP60), and Lon protease-1 (LONP1, a mitochondrial protease), and PI3KP85α within the liver tissue. An in vitro luciferase reporter assay further confirmed that miR-29a mimic directly targets mRNA 3′ untranslated region (UTR) of PI3KP85α to suppress its expression in HepG2 cell line. Our data provide new insights that therapeutic miR-29a improves cholestasis-induced hepatic inflammation and fibrosis and proteotstasis via blocking PI3KP85α, highlighting the potential of miR-29a targeted therapy for liver injury.

scholarly journals Knockdown of cytokeratin 8 overcomes chemoresistance of chordoma cells by aggravating endoplasmic reticulum stress through PERK/eIF2α arm of unfolded protein response and blocking autophagy

2019 ◽  
Vol 10 (12) ◽  
Author(s):  
Di Wang ◽  
Peiran Zhang ◽  
Xiaolong Xu ◽  
Jianhui Wang ◽  
Dong Wang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Unfolded Protein Response ◽  
Xenograft Model ◽  
Spinal Tumor ◽  
Systematic Investigation ◽  
Tumor Xenograft ◽  
Unfolded Protein ◽  
Protein Response

AbstractChordoma is a malignant primary osseous spinal tumor with pronounced chemoresistance. However, the mechanisms of how chordoma cells develop chemoresistance are still not fully understood. Cytokeratin 8 (KRT8) is a molecular marker of notochordal cells, from which chordoma cells were believed to be originated. In this study, we showed that either doxorubicin or irinotecan promoted KRT8 expression in both CM319 and UCH1 cell lines, accompanied by an increased unfolded protein response and autophagy activity. Then, siRNA-mediated knockdown of KRT8 chemosensitized chordoma cells in vitro. Mechanistic studies showed that knockdown of KRT8 followed by chemotherapy aggravated endoplasmic reticulum stress through PERK/eIF2α arm of unfolded protein response and blocked late-stage autophagy. Moreover, suppression of the PERK/eIF2α arm of unfolded protein response using PERK inhibitor GSK2606414 partially rescued the apoptotic chordoma cells but did not reverse the blockage of the autophagy flux. Finally, tumor xenograft model further confirmed the chemosensitizing effects of siKRT8. This study represents the first systematic investigation into the role of KRT8 in chemoresistance of chordoma and our results highlight a possible strategy of targeting KRT8 to overcome chordoma chemoresistance.

scholarly journals Effect of Astragaloside IV on Neural Stem Cell Transplantation in Alzheimer’s Disease Rat Models

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Hu Haiyan ◽  
Yang Rensong ◽  
Jin Guoqin ◽  
Zhang Xueli ◽  
Xia Huaying ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Stem Cells ◽  
Stem Cell ◽  
Learning And Memory ◽  
High Dose ◽  
Astragaloside Iv ◽  
Cell Based Therapy ◽  
Proliferation And Differentiation

Stem cell-based therapy is a promising treatment strategy for neurodegenerative diseases such as Alzheimer’s disease (AD). However, the mechanism underlying the maintenance of renewal and replacement capabilities of endogenous progenitor cells or engrafted stem cells in a pathological environment remains elusive. To investigate the effect of astragaloside IV (ASI) on the proliferation and differentiation of the engrafted neural stem cells (NSCs), we cultured NSCs from the hippocampus of E14 rat embryos, treated the cells with ASI, and then transplanted the cells into the hippocampus of rat AD models.In vitroexperimentation showed that 10−5 M ASI induced NSCs to differentiate intoβ-tubulin III+and GFAP+cells. NSCs transplantation into rat AD models resulted in improvements in learning and memory, especially in the ASI-treated groups. ASI treatment resulted in an increase in the number ofβ-tubulin III+cells in the hippocampus. Further investigation showed that ASI inhibited PS1 expressionin vitroandin vivo. The high-dose ASI downregulated the Notch intracellular domain, whereas the low-dose ASI increased Notch-1 and NICD. In conclusion, ASI treatment resulted in improvements in learning and memory of AD models by promoting NSC proliferation and differentiation partly through the Notch signal pathway.

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