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The role of Drosophila mismatch repair in suppressing recombination between diverged sequences.

Do AT, LaRocque JR - Sci Rep (2015)

Bottom Line: DNA double-strand breaks (DSBs) must be accurately repaired to maintain genomic integrity.DSBs can be repaired by homologous recombination (HR), which uses an identical sequence as a template to restore the genetic information lost at the break.These findings suggest that MMR has an early role in suppressing recombination between diverged sequences that is conserved in Drosophila.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Science, Georgetown University Medical Center, Washington DC 20057.

ABSTRACT
DNA double-strand breaks (DSBs) must be accurately repaired to maintain genomic integrity. DSBs can be repaired by homologous recombination (HR), which uses an identical sequence as a template to restore the genetic information lost at the break. Suppression of recombination between diverged sequences is essential to the repair of DSBs without aberrant and potentially mutagenic recombination between non-identical sequences, such as Alu repeats in the human genome. The mismatch repair (MMR) machinery has been found to suppress recombination between diverged sequences in murine cells. To test if this phenomenon is conserved in whole organisms, two DSB repair systems were utilized in Drosophila melanogaster. The DR-white and DR-white.mu assays provide a method of measuring DSB repair outcomes between identical and diverged sequences respectively. msh6(-/-) flies, deficient in MMR, were not capable of suppressing recombination between sequences with 1.4% divergence, and the average gene conversion tract length did not differ between msh6(-/+) and msh6(-/-)flies. These findings suggest that MMR has an early role in suppressing recombination between diverged sequences that is conserved in Drosophila.

No MeSH data available.


Related in: MedlinePlus

Msh6 suppresses recombination between diverged sequences.Recombination between homologous and diverged sequences in Drosophila melanogaster was determined using DR-white and DR-white.mu, respectively. Recombination between diverged sequences is suppressed in msh6+/+ flies (n = 117 and 67, respectively), as well as in the msh6–/+ heterozygote control (n = 48 and 46, respectively). However, suppression of recombination was not observed in msh6–/– flies (n = 27 and 38, respectively). The average percentage of recombination with SEM is shown from 27–117 single male germlines representative of five independent experiments. Given P values were determined by unpaired t test. For total numbers, including SSA and NHEJ analysis, see Supplementary Tables 1 and 2. msh6+/+ data is from previous work9.
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f3: Msh6 suppresses recombination between diverged sequences.Recombination between homologous and diverged sequences in Drosophila melanogaster was determined using DR-white and DR-white.mu, respectively. Recombination between diverged sequences is suppressed in msh6+/+ flies (n = 117 and 67, respectively), as well as in the msh6–/+ heterozygote control (n = 48 and 46, respectively). However, suppression of recombination was not observed in msh6–/– flies (n = 27 and 38, respectively). The average percentage of recombination with SEM is shown from 27–117 single male germlines representative of five independent experiments. Given P values were determined by unpaired t test. For total numbers, including SSA and NHEJ analysis, see Supplementary Tables 1 and 2. msh6+/+ data is from previous work9.

Mentions: In a previous study, the DR-white assay determined that 39.4 ± 0.90% of progeny from msh6+/+ wild-type flies repaired DSBs via HR. With the incorporation of 28 silent polymorphisms increasing sequence divergence to 1.4% in the DR-white.mu assay, recombination was suppressed to 27.1% (±1.18%), a 31.5% suppression of recombination (P < 0.0000001 by unpaired t test; Fig. 3)9. Similar results were observed in msh6–/+ heterozygotes. Progeny from DR-white; msh6–/+ flies repaired DSBs via HR at a frequency of 36.6 ± 0.02% (703 of 1923), while progeny from DR-white.mu; msh6–/+ flies repaired via recombination at a frequency of 24.7 ± 0.02% (428 of 1736 flies; P < 0.0001, unpaired t test; Fig. 3), resulting in 34.3% suppression of recombination. However, this suppression of recombination between diverged sequences was not observed in msh6–/– flies. Progeny from DR-white; msh6–/– flies repaired DSBs via HR at a frequency of 40.7 ± 0.04% (261 of 645 flies), while progeny from DR-white.mu; msh6–/– flies repaired via recombination at a frequency of 34.3 ± 0.03% (282 of 821 flies; P > 0.05, unpaired t test; Fig. 3, Supplementary Table S1).


The role of Drosophila mismatch repair in suppressing recombination between diverged sequences.

Do AT, LaRocque JR - Sci Rep (2015)

Msh6 suppresses recombination between diverged sequences.Recombination between homologous and diverged sequences in Drosophila melanogaster was determined using DR-white and DR-white.mu, respectively. Recombination between diverged sequences is suppressed in msh6+/+ flies (n = 117 and 67, respectively), as well as in the msh6–/+ heterozygote control (n = 48 and 46, respectively). However, suppression of recombination was not observed in msh6–/– flies (n = 27 and 38, respectively). The average percentage of recombination with SEM is shown from 27–117 single male germlines representative of five independent experiments. Given P values were determined by unpaired t test. For total numbers, including SSA and NHEJ analysis, see Supplementary Tables 1 and 2. msh6+/+ data is from previous work9.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663472&req=5

f3: Msh6 suppresses recombination between diverged sequences.Recombination between homologous and diverged sequences in Drosophila melanogaster was determined using DR-white and DR-white.mu, respectively. Recombination between diverged sequences is suppressed in msh6+/+ flies (n = 117 and 67, respectively), as well as in the msh6–/+ heterozygote control (n = 48 and 46, respectively). However, suppression of recombination was not observed in msh6–/– flies (n = 27 and 38, respectively). The average percentage of recombination with SEM is shown from 27–117 single male germlines representative of five independent experiments. Given P values were determined by unpaired t test. For total numbers, including SSA and NHEJ analysis, see Supplementary Tables 1 and 2. msh6+/+ data is from previous work9.
Mentions: In a previous study, the DR-white assay determined that 39.4 ± 0.90% of progeny from msh6+/+ wild-type flies repaired DSBs via HR. With the incorporation of 28 silent polymorphisms increasing sequence divergence to 1.4% in the DR-white.mu assay, recombination was suppressed to 27.1% (±1.18%), a 31.5% suppression of recombination (P < 0.0000001 by unpaired t test; Fig. 3)9. Similar results were observed in msh6–/+ heterozygotes. Progeny from DR-white; msh6–/+ flies repaired DSBs via HR at a frequency of 36.6 ± 0.02% (703 of 1923), while progeny from DR-white.mu; msh6–/+ flies repaired via recombination at a frequency of 24.7 ± 0.02% (428 of 1736 flies; P < 0.0001, unpaired t test; Fig. 3), resulting in 34.3% suppression of recombination. However, this suppression of recombination between diverged sequences was not observed in msh6–/– flies. Progeny from DR-white; msh6–/– flies repaired DSBs via HR at a frequency of 40.7 ± 0.04% (261 of 645 flies), while progeny from DR-white.mu; msh6–/– flies repaired via recombination at a frequency of 34.3 ± 0.03% (282 of 821 flies; P > 0.05, unpaired t test; Fig. 3, Supplementary Table S1).

Bottom Line: DNA double-strand breaks (DSBs) must be accurately repaired to maintain genomic integrity.DSBs can be repaired by homologous recombination (HR), which uses an identical sequence as a template to restore the genetic information lost at the break.These findings suggest that MMR has an early role in suppressing recombination between diverged sequences that is conserved in Drosophila.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Science, Georgetown University Medical Center, Washington DC 20057.

ABSTRACT
DNA double-strand breaks (DSBs) must be accurately repaired to maintain genomic integrity. DSBs can be repaired by homologous recombination (HR), which uses an identical sequence as a template to restore the genetic information lost at the break. Suppression of recombination between diverged sequences is essential to the repair of DSBs without aberrant and potentially mutagenic recombination between non-identical sequences, such as Alu repeats in the human genome. The mismatch repair (MMR) machinery has been found to suppress recombination between diverged sequences in murine cells. To test if this phenomenon is conserved in whole organisms, two DSB repair systems were utilized in Drosophila melanogaster. The DR-white and DR-white.mu assays provide a method of measuring DSB repair outcomes between identical and diverged sequences respectively. msh6(-/-) flies, deficient in MMR, were not capable of suppressing recombination between sequences with 1.4% divergence, and the average gene conversion tract length did not differ between msh6(-/+) and msh6(-/-)flies. These findings suggest that MMR has an early role in suppressing recombination between diverged sequences that is conserved in Drosophila.

No MeSH data available.


Related in: MedlinePlus