DNA Damage, Checkpoint Responses, and Cell Cycle Control in Aging Stem Cells

Author(s):  
Tobias Sperka ◽  
Kodandaramireddy Nalapareddy ◽  
K. Lenhard Rudolph
2021 ◽  
Vol 22 (15) ◽  
pp. 7813
Author(s):  
Lindsay Kraus ◽  
Chris Bryan ◽  
Marcus Wagner ◽  
Tabito Kino ◽  
Melissa Gunchenko ◽  
...  

Ischemic heart disease can lead to myocardial infarction (MI), a major cause of morbidity and mortality worldwide. Multiple stem cell types have been safely transferred into failing human hearts, but the overall clinical cardiovascular benefits have been modest. Therefore, there is a dire need to understand the basic biology of stem cells to enhance therapeutic effects. Bmi1 is part of the polycomb repressive complex 1 (PRC1) that is involved in different processes including proliferation, survival and differentiation of stem cells. We isolated cortical bones stem cells (CBSCs) from bone stroma, and they express significantly high levels of Bmi1 compared to mesenchymal stem cells (MSCs) and cardiac-derived stem cells (CDCs). Using lentiviral transduction, Bmi1 was knocked down in the CBSCs to determine the effect of loss of Bmi1 on proliferation and survival potential with or without Bmi1 in CBSCs. Our data show that with the loss of Bmi1, there is a decrease in CBSC ability to proliferate and survive during stress. This loss of functionality is attributed to changes in histone modification, specifically histone 3 lysine 27 (H3K27). Without the proper epigenetic regulation, due to the loss of the polycomb protein in CBSCs, there is a significant decrease in cell cycle proteins, including Cyclin B, E2F, and WEE as well as an increase in DNA damage genes, including ataxia-telangiectasia mutated (ATM) and ATM and Rad3-related (ATR). In conclusion, in the absence of Bmi1, CBSCs lose their proliferative potential, have increased DNA damage and apoptosis, and more cell cycle arrest due to changes in epigenetic modifications. Consequently, Bmi1 plays a critical role in stem cell proliferation and survival through cell cycle regulation, specifically in the CBSCs. This regulation is associated with the histone modification and regulation of Bmi1, therefore indicating a novel mechanism of Bmi1 and the epigenetic regulation of stem cells.


eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Eutteum Jeong ◽  
Owen A Brady ◽  
José A Martina ◽  
Mehdi Pirooznia ◽  
Ilker Tunc ◽  
...  

The transcription factors TFE3 and TFEB cooperate to regulate autophagy induction and lysosome biogenesis in response to starvation. Here we demonstrate that DNA damage activates TFE3 and TFEB in a p53 and mTORC1 dependent manner. RNA-Seq analysis of TFEB/TFE3 double-knockout cells exposed to etoposide reveals a profound dysregulation of the DNA damage response, including upstream regulators and downstream p53 targets. TFE3 and TFEB contribute to sustain p53-dependent response by stabilizing p53 protein levels. In TFEB/TFE3 DKOs, p53 half-life is significantly decreased due to elevated Mdm2 levels. Transcriptional profiles of genes involved in lysosome membrane permeabilization and cell death pathways are dysregulated in TFEB/TFE3-depleted cells. Consequently, prolonged DNA damage results in impaired LMP and apoptosis induction. Finally, expression of multiple genes implicated in cell cycle control is altered in TFEB/TFE3 DKOs, revealing a previously unrecognized role of TFEB and TFE3 in the regulation of cell cycle checkpoints in response to stress.


2021 ◽  
Author(s):  
Haiyun Luo ◽  
Wenjing Liu ◽  
Yanli Zhang ◽  
Xiao Jiang ◽  
Shiqing Wu ◽  
...  

Abstract Background: Dental pulp stem cells (DPSCs) exhibited self-renewal, pluripotency capacity and served as promising cells source in endodontic regeneration and tissue engineering. Meanwhile, the regenerative capacity of DPSCs is limited and reduced in long lifespan. N6-methyladenosine (m6A) is the most prevalent, reversible internal modification in RNAs. The methyltransferases complex and demethylases mediated m6A methylation and cooperated to impact various biological processes associated with stem cell fate determination. However, the biological effect of m6A methylation in DPSCs remained unclear. Methods: Cell surface markers and differentiation potential of primary DPSCs were identified and m6A immunoprecipitation with deep sequencing (m6A RIP-seq) was used to uncover characteristics of m6A modifications in DPSCs transcriptome. Expression level of m6A-related genes were evaluated in immature/mature pulp tissues and cells. Lentiviral vectors were constructed to knockdown or overexpress methyltransferase like 3 (METTL3). Cell morphology, viability, senescence and apoptosis were further analyzed by β-galactosidase, TUNEL staining and flow cytometry. Bioinformatic analysis combing m6A RIP and shMETTL3 RNA-seq was used to functionally enrich overlapped genes and screen target of METTL3. Cell cycle distributions were assayed by flow cytometry and m6A RIP-qPCR was used to confirm METTL3 mediated m6A methylation in DPSCs. Results: Here, m6A peaks distribution, binding area and motif in DPSCs were first revealed by m6A RIP-seq. We also found a relative high expression level of METTL3 in immature DPSCs with superior regenerative potential and METTL3 knockdown induced cell apoptosis and senescence. Furthermore, Conjoint analysis of m6A RIP and RNA-sequencing showed differentially expressed genes affected by METTL3 depletion was mainly enriched in cell cycle, mitosis and alteration of METTL3 expression resulted in cell cycle arrest which indicated METTL3 make essential effect in cell cycle control. To further investigate underlying mechanisms, we explored proteins interaction network of differentially expressed genes and Polo-like Kinase 1 (PLK1), a critical cycle modulator was identified as target of METTL3-mediated m6A methylation in DPSCs. Conclusions: These results revealed m6A methylated hallmarks in DPSCs and a regulatory role of METTL3 in cell cycle control. Our study shed light on therapeutic approaches in vital pulp therapy and serve new insight in stem cells based tissue engineering.


2021 ◽  
pp. 237-255
Author(s):  
R. Gundogdu ◽  
A. Hergovich ◽  
V. Gómez

Biomedicines ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 397
Author(s):  
Cheuk Yiu Tenny Chung ◽  
Paulisally Hau Yi Lo ◽  
Kenneth Ka Ho Lee

BRISC and BRCA1-A complex member 2 (Babam2) plays an essential role in promoting cell cycle progression and preventing cellular senescence. Babam2-deficient fibroblasts show proliferation defect and premature senescence compared with their wild-type (WT) counterpart. Pluripotent mouse embryonic stem cells (mESCs) are known to have unlimited cell proliferation and self-renewal capability without entering cellular senescence. Therefore, studying the role of Babam2 in ESCs would enable us to understand the mechanism of Babam2 in cellular aging, cell cycle regulation, and pluripotency in ESCs. For this study, we generated Babam2 knockout (Babam2−/−) mESCs to investigate the function of Babam2 in mESCs. We demonstrated that the loss of Babam2 in mESCs leads to abnormal G1 phase retention in response to DNA damage induced by gamma irradiation or doxorubicin treatments. Key cell cycle regulators, CDC25A and CDK2, were found to be degraded in Babam2−/− mESCs following gamma irradiation. In addition, Babam2−/− mESCs expressed p53 strongly and significantly longer than in control mESCs, where p53 inhibited Nanog expression and G1/S cell cycle progression. The combined effects significantly reduced developmental pluripotency in Babam2−/− mESCs. In summary, Babam2 maintains cell cycle regulation and pluripotency in mESCs in response to induced DNA damage.


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