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Meiotic arrest and aneuploidy in MLH3-deficient mice
Steven M Lipkin1, Peter B Moens, Victoria Wang
1Division of Hematology-Oncology, Department of Medicine, University of California, Irvine, California 92697, USA. slipkin@uci.edu
Abstract:
MutL homolog 3 (Mlh3) is a member of a family of proteins conserved during evolution and having dual roles in DNA mismatch repair and meiosis. The pathway in eukaryotes consists of the DNA-binding components, which are the homologs of the bacterial MutS protein (MSH 2 6), and the MutL homologs, which bind to the MutS homologs and are essential for the repair process. Three of the six homologs of MutS that function in these processes, Msh2, Msh3 and Msh6, are involved in the mismatch repair of mutations, frameshifts and replication errors, and two others, Msh4 and Msh5, have specific roles in meiosis. Of the four MutL homologs, Mlh1, Mlh3, Pms1 and Pms2, three are involved in mismatch repair and at least two, Pms2 and Mlh1, are essential for meiotic progression in both yeast and mice. To assess the role of Mlh3 in mammalian meiosis, we have generated and characterized Mlh3(-/-) mice. Here we show that Mlh3(-/-) mice are viable but sterile. Mlh3 is required for Mlh1 binding to meiotic chromosomes and localizes to meiotic chromosomes from the mid pachynema stage of prophase I. Mlh3(-/-) spermatocytes reach metaphase before succumbing to apoptosis, but oocytes fail to complete meiosis I after fertilization. Our results show that Mlh3 has an essential and distinct role in mammalian meiosis.
Insights
MutL homolog 3 (Mlh3) is crucial for mammalian meiosis. Mlh3-deficient mice are sterile, indicating its essential role in reproductive cell development and chromosome regulation.
Area of Science:
- Genetics
- Cell Biology
- Reproductive Biology
Background:
- MutL homolog 3 (Mlh3) is involved in DNA mismatch repair and meiosis.
- Mlh3 interacts with Mlh1 and localizes to meiotic chromosomes.
- Understanding Mlh3's role is key to mammalian reproductive processes.
Purpose of the Study:
- To investigate the specific function of Mlh3 in mammalian meiosis.
- To characterize the meiotic defects in Mlh3-deficient mice.
Main Methods:
- Generation and characterization of Mlh3 knockout mice (Mlh3(-/-)).
- Analysis of meiotic progression and chromosome behavior in Mlh3(-/-) spermatocytes and oocytes.
Main Results:
- Mlh3(-/-) mice are viable but sterile.
- Mlh3 is essential for Mlh1 binding to meiotic chromosomes.
- Mlh3 deficiency leads to spermatocyte apoptosis and oocyte meiotic arrest.
Conclusions:
- Mlh3 plays an essential and distinct role in mammalian meiosis.
- Mlh3 is required for proper chromosome dynamics and progression through meiosis I.