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Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

Li P, Jin H, Yu HG - Mol. Biol. Cell (2014)

Bottom Line: Condensin is highly enriched at the rDNA region during prophase I, released at the prophase I/metaphase I transition, and reassociates with rDNA before anaphase I onset.We show that condensin plays a dual role in maintaining rDNA stability: it suppresses the formation of Spo11-mediated rDNA breaks, and it promotes DSB processing to ensure proper chromosome segregation.Our work reveals that condensin coordinates meiotic recombination with chromosome segregation at the repetitive rDNA sequence, thereby maintaining genome integrity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370.

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Condensin regulates rDNA recombination and segregation during yeast meiosis in a spo11-dependent manner. (A) Segregation of GFP-marked loci on chromosome XII in the absence of Spo11 during meiosis (HY2193, HY2255, HY2866, HY2895, HY2896, and HY3102). Note that in spo11Δ cells, homologues segregate randomly; for schematic diagrams, see Supplemental Figure 2D. (B) Schematic diagram showing the forced localization of Spo11 to the rDNA array. Note that SPO11-tetR suppresses the spo11Δ (HY2339 and HY3409) phenotype. (C) Forced localization of Spo11 generating DSBs at rDNA. Yeast cells (HY3159) were induced to undergo meiosis, and nucleus surface spreads were prepared for indirect immunofluorescence as in Figure 2C. Rad51 focus formation was determined and quantified. (D) Quantification of rDNA segregation during meiosis I. Both strains are marked with rDNA-tetO/tetR-GFP. More than 200 cells were counted.
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Figure 5: Condensin regulates rDNA recombination and segregation during yeast meiosis in a spo11-dependent manner. (A) Segregation of GFP-marked loci on chromosome XII in the absence of Spo11 during meiosis (HY2193, HY2255, HY2866, HY2895, HY2896, and HY3102). Note that in spo11Δ cells, homologues segregate randomly; for schematic diagrams, see Supplemental Figure 2D. (B) Schematic diagram showing the forced localization of Spo11 to the rDNA array. Note that SPO11-tetR suppresses the spo11Δ (HY2339 and HY3409) phenotype. (C) Forced localization of Spo11 generating DSBs at rDNA. Yeast cells (HY3159) were induced to undergo meiosis, and nucleus surface spreads were prepared for indirect immunofluorescence as in Figure 2C. Rad51 focus formation was determined and quantified. (D) Quantification of rDNA segregation during meiosis I. Both strains are marked with rDNA-tetO/tetR-GFP. More than 200 cells were counted.

Mentions: We hypothesized that abnormal meiotic recombination in condensin mutants leads to rDNA missegregation. To test this hypothesis, we observed rDNA homologue segregation in spo11Δ and spo11Δ PCLB2-BRN1 mutant cells (Figure 5). In the absence of Spo11, Rad51 focus formation, and therefore meiotic DSBs, was essentially eliminated (Supplemental Figure S2, A–C), and homologues did not form linkages and would segregate randomly (i.e., half the time homologues would segregate to opposite spindle poles, and the other half to the same pole; for a diagram, see Supplemental Figure S2D). This random segregation of homologues was indicated in cells with the GFP marker positioned at three tested loci in both homologues: centromere XII, rDNA, and telomere XII (Figure 5A). Without Spo11, PCLB2-BRN1 cells segregated rDNA homologues at a rate similar to that of the spo11Δ single mutant (Figure 5A), suggesting that rDNA homologue linkage formed in the absence of condensin depends on Spo11.


Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

Li P, Jin H, Yu HG - Mol. Biol. Cell (2014)

Condensin regulates rDNA recombination and segregation during yeast meiosis in a spo11-dependent manner. (A) Segregation of GFP-marked loci on chromosome XII in the absence of Spo11 during meiosis (HY2193, HY2255, HY2866, HY2895, HY2896, and HY3102). Note that in spo11Δ cells, homologues segregate randomly; for schematic diagrams, see Supplemental Figure 2D. (B) Schematic diagram showing the forced localization of Spo11 to the rDNA array. Note that SPO11-tetR suppresses the spo11Δ (HY2339 and HY3409) phenotype. (C) Forced localization of Spo11 generating DSBs at rDNA. Yeast cells (HY3159) were induced to undergo meiosis, and nucleus surface spreads were prepared for indirect immunofluorescence as in Figure 2C. Rad51 focus formation was determined and quantified. (D) Quantification of rDNA segregation during meiosis I. Both strains are marked with rDNA-tetO/tetR-GFP. More than 200 cells were counted.
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Related In: Results  -  Collection

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Figure 5: Condensin regulates rDNA recombination and segregation during yeast meiosis in a spo11-dependent manner. (A) Segregation of GFP-marked loci on chromosome XII in the absence of Spo11 during meiosis (HY2193, HY2255, HY2866, HY2895, HY2896, and HY3102). Note that in spo11Δ cells, homologues segregate randomly; for schematic diagrams, see Supplemental Figure 2D. (B) Schematic diagram showing the forced localization of Spo11 to the rDNA array. Note that SPO11-tetR suppresses the spo11Δ (HY2339 and HY3409) phenotype. (C) Forced localization of Spo11 generating DSBs at rDNA. Yeast cells (HY3159) were induced to undergo meiosis, and nucleus surface spreads were prepared for indirect immunofluorescence as in Figure 2C. Rad51 focus formation was determined and quantified. (D) Quantification of rDNA segregation during meiosis I. Both strains are marked with rDNA-tetO/tetR-GFP. More than 200 cells were counted.
Mentions: We hypothesized that abnormal meiotic recombination in condensin mutants leads to rDNA missegregation. To test this hypothesis, we observed rDNA homologue segregation in spo11Δ and spo11Δ PCLB2-BRN1 mutant cells (Figure 5). In the absence of Spo11, Rad51 focus formation, and therefore meiotic DSBs, was essentially eliminated (Supplemental Figure S2, A–C), and homologues did not form linkages and would segregate randomly (i.e., half the time homologues would segregate to opposite spindle poles, and the other half to the same pole; for a diagram, see Supplemental Figure S2D). This random segregation of homologues was indicated in cells with the GFP marker positioned at three tested loci in both homologues: centromere XII, rDNA, and telomere XII (Figure 5A). Without Spo11, PCLB2-BRN1 cells segregated rDNA homologues at a rate similar to that of the spo11Δ single mutant (Figure 5A), suggesting that rDNA homologue linkage formed in the absence of condensin depends on Spo11.

Bottom Line: Condensin is highly enriched at the rDNA region during prophase I, released at the prophase I/metaphase I transition, and reassociates with rDNA before anaphase I onset.We show that condensin plays a dual role in maintaining rDNA stability: it suppresses the formation of Spo11-mediated rDNA breaks, and it promotes DSB processing to ensure proper chromosome segregation.Our work reveals that condensin coordinates meiotic recombination with chromosome segregation at the repetitive rDNA sequence, thereby maintaining genome integrity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370.

Show MeSH
Related in: MedlinePlus