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Histone supply regulates S phase timing and cell cycle progression.

Günesdogan U, Jäckle H, Herzig A - Elife (2014)

Bottom Line: During DNA replication, nucleosomes are disrupted and re-assembled with newly synthesized histones and DNA.We used a histone mutation of Drosophila melanogaster to show that histone supply levels, provided by a defined number of transgenic histone genes, regulate the length of S phase during the cell cycle.Lack of de novo histone supply not only extends S phase, but also causes a cell cycle arrest during G2 phase, and thus prevents cells from entering mitosis.

View Article: PubMed Central - PubMed

Affiliation: Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom.

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HisC mutant embryos do not show accumulation of DNA damage during early embryogenesis.(A–H) TUNEL assays with whole mount embryos to detect free 3′OH groups of DNA, which indicate DNA damage. (A–C) Wild type embryos at 4.5–5 hr AEL contained a few apoptotic cells (arrowheads). In most nuclei, free 3′OH groups were not detected. (D) Whole mount wild type embryos at 9.5–10 hr AEL showed a few apoptotic cells. (E–G) HisC mutant embryos at 6.5–7 hr AEL also contained a few apoptotic cells (arrowheads). However, the level of TUNEL staining was not uniformly elevated in the mutant cells, indicating that there is no increase of DNA damage compared to wild type. (H) HisC mutant embryos die around 9.5–10 hr AEL and show an increased number of apoptotic cells. Scale bars: 10 µm (A–C), (E–G), 100 µm (D and H).DOI:http://dx.doi.org/10.7554/eLife.02443.012
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fig4s2: HisC mutant embryos do not show accumulation of DNA damage during early embryogenesis.(A–H) TUNEL assays with whole mount embryos to detect free 3′OH groups of DNA, which indicate DNA damage. (A–C) Wild type embryos at 4.5–5 hr AEL contained a few apoptotic cells (arrowheads). In most nuclei, free 3′OH groups were not detected. (D) Whole mount wild type embryos at 9.5–10 hr AEL showed a few apoptotic cells. (E–G) HisC mutant embryos at 6.5–7 hr AEL also contained a few apoptotic cells (arrowheads). However, the level of TUNEL staining was not uniformly elevated in the mutant cells, indicating that there is no increase of DNA damage compared to wild type. (H) HisC mutant embryos die around 9.5–10 hr AEL and show an increased number of apoptotic cells. Scale bars: 10 µm (A–C), (E–G), 100 µm (D and H).DOI:http://dx.doi.org/10.7554/eLife.02443.012

Mentions: To independently address the extend of DNA damage accumulation in HisC mutant embryos, we used TUNEL assays which support that HisC mutant cells do not accumulate significant levels of DNA damage until much later in development (≥10 hr AEL) when these embryos die (Figure 4—figure supplement 2). Finally, we performed genetic tests using mutants of loki (lok), the Drosophila DNA damage checkpoint kinase chk2 (Xu et al., 2001). Homozygous lok mutants are viable and fertile. In contrast, lok, HisC double mutant embryos exhibited the HisC phenotype (Figure 4F–H). Hence, the cell cycle arrest in HisC mutant embryos is not mediated by the chk2-dependent DNA damage checkpoint pathway.


Histone supply regulates S phase timing and cell cycle progression.

Günesdogan U, Jäckle H, Herzig A - Elife (2014)

HisC mutant embryos do not show accumulation of DNA damage during early embryogenesis.(A–H) TUNEL assays with whole mount embryos to detect free 3′OH groups of DNA, which indicate DNA damage. (A–C) Wild type embryos at 4.5–5 hr AEL contained a few apoptotic cells (arrowheads). In most nuclei, free 3′OH groups were not detected. (D) Whole mount wild type embryos at 9.5–10 hr AEL showed a few apoptotic cells. (E–G) HisC mutant embryos at 6.5–7 hr AEL also contained a few apoptotic cells (arrowheads). However, the level of TUNEL staining was not uniformly elevated in the mutant cells, indicating that there is no increase of DNA damage compared to wild type. (H) HisC mutant embryos die around 9.5–10 hr AEL and show an increased number of apoptotic cells. Scale bars: 10 µm (A–C), (E–G), 100 µm (D and H).DOI:http://dx.doi.org/10.7554/eLife.02443.012
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4157229&req=5

fig4s2: HisC mutant embryos do not show accumulation of DNA damage during early embryogenesis.(A–H) TUNEL assays with whole mount embryos to detect free 3′OH groups of DNA, which indicate DNA damage. (A–C) Wild type embryos at 4.5–5 hr AEL contained a few apoptotic cells (arrowheads). In most nuclei, free 3′OH groups were not detected. (D) Whole mount wild type embryos at 9.5–10 hr AEL showed a few apoptotic cells. (E–G) HisC mutant embryos at 6.5–7 hr AEL also contained a few apoptotic cells (arrowheads). However, the level of TUNEL staining was not uniformly elevated in the mutant cells, indicating that there is no increase of DNA damage compared to wild type. (H) HisC mutant embryos die around 9.5–10 hr AEL and show an increased number of apoptotic cells. Scale bars: 10 µm (A–C), (E–G), 100 µm (D and H).DOI:http://dx.doi.org/10.7554/eLife.02443.012
Mentions: To independently address the extend of DNA damage accumulation in HisC mutant embryos, we used TUNEL assays which support that HisC mutant cells do not accumulate significant levels of DNA damage until much later in development (≥10 hr AEL) when these embryos die (Figure 4—figure supplement 2). Finally, we performed genetic tests using mutants of loki (lok), the Drosophila DNA damage checkpoint kinase chk2 (Xu et al., 2001). Homozygous lok mutants are viable and fertile. In contrast, lok, HisC double mutant embryos exhibited the HisC phenotype (Figure 4F–H). Hence, the cell cycle arrest in HisC mutant embryos is not mediated by the chk2-dependent DNA damage checkpoint pathway.

Bottom Line: During DNA replication, nucleosomes are disrupted and re-assembled with newly synthesized histones and DNA.We used a histone mutation of Drosophila melanogaster to show that histone supply levels, provided by a defined number of transgenic histone genes, regulate the length of S phase during the cell cycle.Lack of de novo histone supply not only extends S phase, but also causes a cell cycle arrest during G2 phase, and thus prevents cells from entering mitosis.

View Article: PubMed Central - PubMed

Affiliation: Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom.

Show MeSH
Related in: MedlinePlus