Proliferative behaviour of high-ploidy cells in two murine tumour lines

The presence of high-ploidy cells in malignant tumours has long been documented. However, the biological significance of these cells is not known and there is a great deal of controversy over their proliferative potential. We have analysed the behaviour of these cells in two murine tumour lines, B16F10 melanoma and 3T3A31M angiosarcoma, determining their DNA content by microspectrophotometry and using time-lapse film studies. We have found a discrepancy between the presence of high-ploidy cells in metaphase and the absence of hyperploid telophases. High-ploidy metaphases may be aborted (mitotic polyploidization), prolonged in time or evolve in the form of multipolar, generally tripolar, mitoses. Our results suggest that high-ploidy cells are capable of proliferating, despite certain peculiarities in their cell cycle, and constitute a tumour subpopulation whose role in neoplasia merits further study.

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Isolation of cardiomyocytes undergoing mitosis with complete cytokinesis

10.1101/549212 ◽

2019 ◽

Author(s):

Hsiao-yun Y. Milliron ◽

Matthew J. Weiland ◽

Eric J. Kort ◽

Stefan Jovinge

Keyword(s):

Cell Cycle ◽

Cell Division ◽

Dna Content ◽

Cell Cycle Progression ◽

Time Lapse ◽

Heart Tissue ◽

Molecular Beacons ◽

Human Cardiomyocytes ◽

Complete Cell ◽

Proliferation Assays

AbstractRationale-Adult human cardiomyocytes (CMs) do not complete cytokinesis despite passing through the S-phase of the cell cycle. As a result polyploidization and multinucleation occur. In order to get a deeper understanding of the mechanisms surrounding division of CMs there is a crucial need for a technique to isolate CMs that complete cell division/cytokinesis.Objective-Markers of cell cycle progression based on DNA content cannot distinguish between mitotic CMs that fail to complete cytokinesis from those cells that undergo true cell division. With the use of molecular beacons (MB) targeting specific mRNAs we aimed to identify truly proliferative CMs derived from hiPSCs.Methods and Results-Fluorescence activated cell-sorting combined with molecular beacons was performed to sort CM populations enriched for mitotic cells. Expressions of cell-cycle specific genes were confirmed by means of RT-qPCR, single-cell RNA sequencing (scRNA-seq). We further characterized the sorted groups by proliferation assays and time-lapse microscopy which confirmed the proliferative advantage of MB-positive cell populations relative to MB-negative and G2/M populations. Gene expression analysis revealed that the MB-positive CM subpopulation exhibited patterns consistent with the biological processes of nuclear division, chromosome segregation, and transition from M to G1 phase. The use of dual-MBs targeting CDC20 and SPG20 mRNAs (CDC20+SPG20+) enabled the enrichment of cytokinetic events. Interestingly, cells that did not complete cytokinesis and remained binucleated were found to be CDC20−SPG20+ while polyploid CMs that replicated DNA but failed to complete karyokinesis were found to be CDC20−SPG20−.Conclusions-This study demonstrates a novel alternative to existing DNA content-based approaches for sorting CMs with true mitotic potential that can be used to study in detail the unique dynamics of CM nuclei during mitosis. Together with high-throughput scRNA-seq, our technique for sorting live CMs undergoing cytokinesis would provide a basis for future studies to uncover mechanisms underlying the development and regeneration of heart tissue.

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Bmi1 Augments Proliferation and Survival of Cortical Bone-Derived Stem Cells after Injury through Novel Epigenetic Signaling via Histone 3 Regulation

International Journal of Molecular Sciences ◽

10.3390/ijms22157813 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7813

Author(s):

Lindsay Kraus ◽

Chris Bryan ◽

Marcus Wagner ◽

Tabito Kino ◽

Melissa Gunchenko ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Dna Damage ◽

Stem Cell ◽

Histone Modification ◽

Epigenetic Regulation ◽

Critical Role ◽

Proliferative Potential ◽

Therapeutic Effects ◽

Histone 3

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.

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Quiescent, Slow-Cycling Stem Cell Populations in Cancer: A Review of the Evidence and Discussion of Significance

Journal of Oncology ◽

10.1155/2011/396076 ◽

2011 ◽

Vol 2011 ◽

pp. 1-11 ◽

Cited By ~ 159

Author(s):

Nathan Moore ◽

Stephen Lyle

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Stem Cell ◽

Cancer Stem Cells ◽

Adult Stem Cells ◽

Cell Populations ◽

Proliferative Potential ◽

Cell Cycle Regulators ◽

Slow Cycling ◽

Stem Cell Populations

Long-lived cancer stem cells (CSCs) with indefinite proliferative potential have been identified in multiple epithelial cancer types. These cells are likely derived from transformed adult stem cells and are thought to share many characteristics with their parental population, including a quiescent slow-cycling phenotype. Various label-retaining techniques have been used to identify normal slow cycling adult stem cell populations and offer a unique methodology to functionally identify and isolate cancer stem cells. The quiescent nature of CSCs represents an inherent mechanism that at least partially explains chemotherapy resistance and recurrence in posttherapy cancer patients. Isolating and understanding the cell cycle regulatory mechanisms of quiescent cancer cells will be a key component to creation of future therapies that better target CSCs and totally eradicate tumors. Here we review the evidence for quiescent CSC populations and explore potential cell cycle regulators that may serve as future targets for elimination of these cells.

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Live-cell time-lapse imaging and single-cell tracking of in vitro cultured neural stem cells – Tools for analyzing dynamics of cell cycle, migration, and lineage selection

Methods ◽

10.1016/j.ymeth.2017.10.003 ◽

2018 ◽

Vol 133 ◽

pp. 81-90 ◽

Cited By ~ 11

Author(s):

Katja M. Piltti ◽

Brian J. Cummings ◽

Krystal Carta ◽

Ayla Manughian-Peter ◽

Colleen L. Worne ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Neural Stem Cells ◽

Single Cell ◽

Cell Tracking ◽

Time Lapse ◽

Live Cell ◽

Time Lapse Imaging

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Cell cycle dynamics of NG2 cells in the postnatal and ageing brain

Neuron Glia Biology ◽

10.1017/s1740925x09990354 ◽

2009 ◽

Vol 5 (3-4) ◽

pp. 57-67 ◽

Cited By ~ 138

Author(s):

Konstantina Psachoulia ◽

Francoise Jamen ◽

Kaylene M. Young ◽

William D. Richardson

Keyword(s):

Cell Cycle ◽

Corpus Callosum ◽

Biological Significance ◽

Growth Fraction ◽

Cell Cycle Time ◽

Active Population ◽

Dorsal Telencephalon ◽

Ng2 Cells ◽

Cell Cycle Dynamics ◽

Ageing Brain

Oligodendrocyte precursors (OLPs or ‘NG2 cells’) are abundant in the adult mouse brain, where they continue to proliferate and generate new myelinating oligodendrocytes. By cumulative BrdU labelling, we estimated the cell cycle timeTCand the proportion of NG2 cells that is actively cycling (the growth fraction) at ~ postnatal day 6 (P6), P60, P240 and P540. In the corpus callosum,TCincreased from <2 days at P6 to ~9 days at P60 to ~70 days at P240 and P540. In the cortex,TCincreased from ~2 days to >150 days over the same period. The growth fraction remained relatively invariant at ~50% in both cortex and corpus callosum – that is, similar numbers of mitotically active and inactive NG2 cells co-exist at all ages. Our data imply that a stable population of quiescent NG2 cells appears before the end of the first postnatal week and persists throughout life. The mitotically active population acts as a source of new oligodendrocytes during adulthood, while the biological significance of the quiescent population remains to be determined. We found that the mitotic status of adult NG2 cells is unrelated to their developmental site of origin in the ventral or dorsal telencephalon. We also report that new oligodendrocytes continue to be formed at a slow rate from NG2 cells even after P240 (8 months of age).

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Nuclear DNA content and minimum generation time in herbaceous plants

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1972.0042 ◽

1972 ◽

Vol 181 (1063) ◽

pp. 109-135 ◽

Cited By ~ 406

Keyword(s):

Cell Cycle ◽

Dna Content ◽

Cycle Time ◽

Generation Time ◽

Nuclear Dna ◽

Nuclear Dna Content ◽

Annual Species ◽

Cell Cycle Time ◽

Developmental Processes ◽

The Mean

Many components of cell and nuclear size and mass are correlated with nuclear DNA content in plants, as also are the durations and rates of such developmental processes as mitosis and meiosis. It is suggested that the multiple effects of the mass of nuclear DNA which affect all cells and apply throughout the life of the plant can together determine the minimum generation time for each species. The durations of mitosis and of meiosis are both positively correlated with nuclear DNA content and, therefore, species with a short minimum generation time might be expected to have a shorter mean cell cycle time and mean meiotic duration, and a lower mean nuclear DNA content, than species with a long mean minimum generation time. In tests of this hypothesis, using data collated from the literature, it is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species. Furthermore, the mean nuclear DNA content of annual species is significantly lower than for perennial species both in dicotyledons and monocotyledons. Ephemeral species have a significantly lower mean nuclear DNA content than annual species. Among perennial monocotyledons the mean nuclear DNA content of species which can complete a life cycle within one year (facultative perennials) is significantly lower than the mean nuclear DNA content of those which cannot (obligate perennials). However, the mean nuclear DNA content of facultative perennials does not differ significantly from the mean for annual species. It is suggested that the effects of nuclear DNA content on the duration of developmental processes are most obvious during its determinant stages, and that the largest effects of nuclear DNA mass are expressed at times when development is slowest, for instance, during meiosis or at low temperature. It has been suggested that DNA influences development in two ways, directly through its informational content, and indirectly by the physical-mechanical effects of its mass. The term 'nucleotype' is used to describe those conditions of the nucleus which effect the phenotype independently of the informational content of the DNA. It is suggested that cell cycle time, meiotic duration, and minimum generation time are determined by the nucleotype. In addition, it may be that satellite DNA is significant in its nucleotypic effects on developmental processes.

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