Limits...
Localization of MMR proteins on meiotic chromosomes in mice indicates distinct functions during prophase I.

Kolas NK, Svetlanov A, Lenzi ML, Macaluso FP, Lipkin SM, Liskay RM, Greally J, Edelmann W, Cohen PE - J. Cell Biol. (2005)

Bottom Line: Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects.This complex is up-regulated in Pms2-/- males, but not females, providing an explanation for the sexual dimorphism seen in Pms2-/- mice.The association of MLH3 with repetitive DNA sequences is coincident with MSH2-MSH3 and is decreased in Msh2-/- and Msh3-/- mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

ABSTRACT
Mammalian MutL homologues function in DNA mismatch repair (MMR) after replication errors and in meiotic recombination. Both functions are initiated by a heterodimer of MutS homologues specific to either MMR (MSH2-MSH3 or MSH2-MSH6) or crossing over (MSH4-MSH5). Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects. We show herein that two distinct complexes involving MLH3 are formed during murine meiosis. The first is a stable association between MLH3 and MLH1 and is involved in promoting crossing over in conjunction with MSH4-MSH5. The second complex involves MLH3 together with MSH2-MSH3 and localizes to repetitive sequences at centromeres and the Y chromosome. This complex is up-regulated in Pms2-/- males, but not females, providing an explanation for the sexual dimorphism seen in Pms2-/- mice. The association of MLH3 with repetitive DNA sequences is coincident with MSH2-MSH3 and is decreased in Msh2-/- and Msh3-/- mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis.

Show MeSH

Related in: MedlinePlus

Localization of MSH2 to the centromere regions of meiotic chromosomes is dependent on MSH3 but not MSH6 and PMS2. (A–C) MSH2 localization to meiotic chromosome cores in a representative spermatocyte from a Pms2−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC) and the centromere in blue (CY5-CREST). Panel C shows the superimposed channels from panels A and B. (D–F) MSH2 localization to meiotic chromosomes in two representative spermatocytes from a Msh3−/− male. MSH2 is shown in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In the absence of MSH3, no MSH2 signal is apparent. (G–I) MSH2 localization to meiotic chromosomes in a representative spermatocyte from a Msh6−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In A, D, and G, white arrowheads indicate interstitial localization of MSH2 along chromosome cores. (J) For each genotype, 5–10 cells were quantitated and the percentage of centromeres showing fluorescent signal for MSH2 was scored.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2171243&req=5

fig7: Localization of MSH2 to the centromere regions of meiotic chromosomes is dependent on MSH3 but not MSH6 and PMS2. (A–C) MSH2 localization to meiotic chromosome cores in a representative spermatocyte from a Pms2−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC) and the centromere in blue (CY5-CREST). Panel C shows the superimposed channels from panels A and B. (D–F) MSH2 localization to meiotic chromosomes in two representative spermatocytes from a Msh3−/− male. MSH2 is shown in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In the absence of MSH3, no MSH2 signal is apparent. (G–I) MSH2 localization to meiotic chromosomes in a representative spermatocyte from a Msh6−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In A, D, and G, white arrowheads indicate interstitial localization of MSH2 along chromosome cores. (J) For each genotype, 5–10 cells were quantitated and the percentage of centromeres showing fluorescent signal for MSH2 was scored.

Mentions: Immunofluorescence analysis of chromosome preparations from wild-type spermatocytes demonstrated that MSH2 and MSH3 localize strongly to the centromere (Fig. 6, A–F) and on the sex chromosomes (Fig. 6, C and F, arrows), and that this localization is as frequent in wild-type spermatocytes as it is in Pms2−/− males (Fig. 7, A–C and J). These observations indicate that the association of MSH2–MSH3-containing complexes appear to be a feature of normal prophase I and are not specifically up-regulated in the absence of PMS2. No association of MSH2 with these genomic regions is observed in spermatocytes from Msh3−/− males either by immunofluorescence or EM (Fig. 6 G and Fig. 7, D–F), indicating that MSH3 is required for MSH2 localization to these sites. By contrast, immunofluorescence and immunogold localization of MSH2 at the centromere is not affected in spermatocytes from Msh4−/−, Msh5−/−, or Msh6−/− males (Fig. 6, H and I, and Fig. 7, G–J). MSH2, and to a lesser degree MSH3, localizes along the chromosomes, but at an intensity that is far lower than that seen at the centromere (Fig. 6, A and D, arrowheads; Fig. 7, A and G, arrowheads). This interstitial localization could be the result of canonical MMR activity.


Localization of MMR proteins on meiotic chromosomes in mice indicates distinct functions during prophase I.

Kolas NK, Svetlanov A, Lenzi ML, Macaluso FP, Lipkin SM, Liskay RM, Greally J, Edelmann W, Cohen PE - J. Cell Biol. (2005)

Localization of MSH2 to the centromere regions of meiotic chromosomes is dependent on MSH3 but not MSH6 and PMS2. (A–C) MSH2 localization to meiotic chromosome cores in a representative spermatocyte from a Pms2−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC) and the centromere in blue (CY5-CREST). Panel C shows the superimposed channels from panels A and B. (D–F) MSH2 localization to meiotic chromosomes in two representative spermatocytes from a Msh3−/− male. MSH2 is shown in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In the absence of MSH3, no MSH2 signal is apparent. (G–I) MSH2 localization to meiotic chromosomes in a representative spermatocyte from a Msh6−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In A, D, and G, white arrowheads indicate interstitial localization of MSH2 along chromosome cores. (J) For each genotype, 5–10 cells were quantitated and the percentage of centromeres showing fluorescent signal for MSH2 was scored.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171243&req=5

fig7: Localization of MSH2 to the centromere regions of meiotic chromosomes is dependent on MSH3 but not MSH6 and PMS2. (A–C) MSH2 localization to meiotic chromosome cores in a representative spermatocyte from a Pms2−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC) and the centromere in blue (CY5-CREST). Panel C shows the superimposed channels from panels A and B. (D–F) MSH2 localization to meiotic chromosomes in two representative spermatocytes from a Msh3−/− male. MSH2 is shown in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In the absence of MSH3, no MSH2 signal is apparent. (G–I) MSH2 localization to meiotic chromosomes in a representative spermatocyte from a Msh6−/− male. MSH2 is localized in red (TRITC), SYCP3 in green (FITC), and the centromere in blue (CY5-CREST). In A, D, and G, white arrowheads indicate interstitial localization of MSH2 along chromosome cores. (J) For each genotype, 5–10 cells were quantitated and the percentage of centromeres showing fluorescent signal for MSH2 was scored.
Mentions: Immunofluorescence analysis of chromosome preparations from wild-type spermatocytes demonstrated that MSH2 and MSH3 localize strongly to the centromere (Fig. 6, A–F) and on the sex chromosomes (Fig. 6, C and F, arrows), and that this localization is as frequent in wild-type spermatocytes as it is in Pms2−/− males (Fig. 7, A–C and J). These observations indicate that the association of MSH2–MSH3-containing complexes appear to be a feature of normal prophase I and are not specifically up-regulated in the absence of PMS2. No association of MSH2 with these genomic regions is observed in spermatocytes from Msh3−/− males either by immunofluorescence or EM (Fig. 6 G and Fig. 7, D–F), indicating that MSH3 is required for MSH2 localization to these sites. By contrast, immunofluorescence and immunogold localization of MSH2 at the centromere is not affected in spermatocytes from Msh4−/−, Msh5−/−, or Msh6−/− males (Fig. 6, H and I, and Fig. 7, G–J). MSH2, and to a lesser degree MSH3, localizes along the chromosomes, but at an intensity that is far lower than that seen at the centromere (Fig. 6, A and D, arrowheads; Fig. 7, A and G, arrowheads). This interstitial localization could be the result of canonical MMR activity.

Bottom Line: Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects.This complex is up-regulated in Pms2-/- males, but not females, providing an explanation for the sexual dimorphism seen in Pms2-/- mice.The association of MLH3 with repetitive DNA sequences is coincident with MSH2-MSH3 and is decreased in Msh2-/- and Msh3-/- mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

ABSTRACT
Mammalian MutL homologues function in DNA mismatch repair (MMR) after replication errors and in meiotic recombination. Both functions are initiated by a heterodimer of MutS homologues specific to either MMR (MSH2-MSH3 or MSH2-MSH6) or crossing over (MSH4-MSH5). Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects. We show herein that two distinct complexes involving MLH3 are formed during murine meiosis. The first is a stable association between MLH3 and MLH1 and is involved in promoting crossing over in conjunction with MSH4-MSH5. The second complex involves MLH3 together with MSH2-MSH3 and localizes to repetitive sequences at centromeres and the Y chromosome. This complex is up-regulated in Pms2-/- males, but not females, providing an explanation for the sexual dimorphism seen in Pms2-/- mice. The association of MLH3 with repetitive DNA sequences is coincident with MSH2-MSH3 and is decreased in Msh2-/- and Msh3-/- mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis.

Show MeSH
Related in: MedlinePlus