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An increase in mitochondrial DNA promotes nuclear DNA replication in yeast.

Blank HM, Li C, Mueller JE, Bogomolnaya LM, Bryk M, Polymenis M - PLoS Genet. (2008)

Bottom Line: The Sir2p NAD+-dependent de-acetylase antagonizes this mitochondrial role.We found that cells with increased mitochondrial DNA have reduced Sir2p levels bound at origins of DNA replication in the nucleus, accompanied with increased levels of K9, K14-acetylated histone H3 at those origins.They also suggest that cellular metabolism may impact on chromatin modifications to regulate the activity of origins of DNA replication.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America.

ABSTRACT
Coordination between cellular metabolism and DNA replication determines when cells initiate division. It has been assumed that metabolism only plays a permissive role in cell division. While blocking metabolism arrests cell division, it is not known whether an up-regulation of metabolic reactions accelerates cell cycle transitions. Here, we show that increasing the amount of mitochondrial DNA accelerates overall cell proliferation and promotes nuclear DNA replication, in a nutrient-dependent manner. The Sir2p NAD+-dependent de-acetylase antagonizes this mitochondrial role. We found that cells with increased mitochondrial DNA have reduced Sir2p levels bound at origins of DNA replication in the nucleus, accompanied with increased levels of K9, K14-acetylated histone H3 at those origins. Our results demonstrate an active role of mitochondrial processes in the control of cell division. They also suggest that cellular metabolism may impact on chromatin modifications to regulate the activity of origins of DNA replication.

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Related in: MedlinePlus

Loss of SIR2 in cells over-expressing ABF2 dramatically accelerates DNA replication when NADH is depleted.Cell cycle progression was monitored after elutriation as in Figure 4, except that 10 mM acetaldehyde was added to the starting samples.
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pgen-1000047-g007: Loss of SIR2 in cells over-expressing ABF2 dramatically accelerates DNA replication when NADH is depleted.Cell cycle progression was monitored after elutriation as in Figure 4, except that 10 mM acetaldehyde was added to the starting samples.

Mentions: A protein linked to both metabolism and DNA replication is the Sir2p sirtuin [11], which negatively impacts DNA replication [16]–[18]. Consequently, we evaluated cell cycle progression of cells lacking Sir2p alone, or in combination with Abf2p over-expression (Figure 4). Comparison of ABF2+, SIR2+ (Figure 4, top row) to ABF2+, sir2Δ (Figure 4, third row) cells at 60 min shows that cells lacking SIR2 initiated and completed S phase significantly sooner than wild type cells. Initiation of DNA replication was further accelerated in 3xABF2+, sir2Δ cells (Figure 4, bottom row). We repeated this analysis several times, as we described earlier (Figure S1). Interestingly, 3xABF2+, sir2Δ cells bud at a smaller size (36.1±0.5 fl, n = 5, P = 0.0009, based on a 2-tailed Student's t test) than ABF2+, SIR2+ cells (38.6±1.1 fl, n = 6) (Figure S1D). This explains the apparent additive acceleration of START we observed in 3xABF2+, sir2Δ cells (Figure 4, compare at 40 min the 3xABF2+, sir2Δ strain to other strains, and see also Figure 7, below). Taking into account the critical budding size and the rate of cell size increase for each strain, for 3xABF2+, sir2Δ newborn daughter cells of 20 fl, it will take on average 128 min to start budding, compared to 169 min for ABF2+, SIR2+ daughters. Finally, loss of Sir2p does not increase the amount of mtDNA in the cell (Figure S3).


An increase in mitochondrial DNA promotes nuclear DNA replication in yeast.

Blank HM, Li C, Mueller JE, Bogomolnaya LM, Bryk M, Polymenis M - PLoS Genet. (2008)

Loss of SIR2 in cells over-expressing ABF2 dramatically accelerates DNA replication when NADH is depleted.Cell cycle progression was monitored after elutriation as in Figure 4, except that 10 mM acetaldehyde was added to the starting samples.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2289842&req=5

pgen-1000047-g007: Loss of SIR2 in cells over-expressing ABF2 dramatically accelerates DNA replication when NADH is depleted.Cell cycle progression was monitored after elutriation as in Figure 4, except that 10 mM acetaldehyde was added to the starting samples.
Mentions: A protein linked to both metabolism and DNA replication is the Sir2p sirtuin [11], which negatively impacts DNA replication [16]–[18]. Consequently, we evaluated cell cycle progression of cells lacking Sir2p alone, or in combination with Abf2p over-expression (Figure 4). Comparison of ABF2+, SIR2+ (Figure 4, top row) to ABF2+, sir2Δ (Figure 4, third row) cells at 60 min shows that cells lacking SIR2 initiated and completed S phase significantly sooner than wild type cells. Initiation of DNA replication was further accelerated in 3xABF2+, sir2Δ cells (Figure 4, bottom row). We repeated this analysis several times, as we described earlier (Figure S1). Interestingly, 3xABF2+, sir2Δ cells bud at a smaller size (36.1±0.5 fl, n = 5, P = 0.0009, based on a 2-tailed Student's t test) than ABF2+, SIR2+ cells (38.6±1.1 fl, n = 6) (Figure S1D). This explains the apparent additive acceleration of START we observed in 3xABF2+, sir2Δ cells (Figure 4, compare at 40 min the 3xABF2+, sir2Δ strain to other strains, and see also Figure 7, below). Taking into account the critical budding size and the rate of cell size increase for each strain, for 3xABF2+, sir2Δ newborn daughter cells of 20 fl, it will take on average 128 min to start budding, compared to 169 min for ABF2+, SIR2+ daughters. Finally, loss of Sir2p does not increase the amount of mtDNA in the cell (Figure S3).

Bottom Line: The Sir2p NAD+-dependent de-acetylase antagonizes this mitochondrial role.We found that cells with increased mitochondrial DNA have reduced Sir2p levels bound at origins of DNA replication in the nucleus, accompanied with increased levels of K9, K14-acetylated histone H3 at those origins.They also suggest that cellular metabolism may impact on chromatin modifications to regulate the activity of origins of DNA replication.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America.

ABSTRACT
Coordination between cellular metabolism and DNA replication determines when cells initiate division. It has been assumed that metabolism only plays a permissive role in cell division. While blocking metabolism arrests cell division, it is not known whether an up-regulation of metabolic reactions accelerates cell cycle transitions. Here, we show that increasing the amount of mitochondrial DNA accelerates overall cell proliferation and promotes nuclear DNA replication, in a nutrient-dependent manner. The Sir2p NAD+-dependent de-acetylase antagonizes this mitochondrial role. We found that cells with increased mitochondrial DNA have reduced Sir2p levels bound at origins of DNA replication in the nucleus, accompanied with increased levels of K9, K14-acetylated histone H3 at those origins. Our results demonstrate an active role of mitochondrial processes in the control of cell division. They also suggest that cellular metabolism may impact on chromatin modifications to regulate the activity of origins of DNA replication.

Show MeSH
Related in: MedlinePlus