The synaptonemal complex (SC) is an evolutionarily-conserved protein assembly that holds together homologous chromosomes during prophase of the first meiotic division. Whilst essential for meiosis and fertility, the molecular structure of the SC has proved resistant to elucidation. The SC protein SYCP3 has a crucial but poorly understood role in establishing the architecture of the meiotic chromosome. Here we show that human SYCP3 forms a highly-elongated helical tetramer of 20 nm length. N-terminal sequences extending from each end of the rod-like structure bind double-stranded DNA, enabling SYCP3 to link distant sites along the sister chromatid. We further find that SYCP3 self-assembles into regular filamentous structures that resemble the known morphology of the SC lateral element. Together, our data form the basis for a model in which SYCP3 binding and assembly on meiotic chromosomes leads to their organisation into compact structures compatible with recombination and crossover formation.
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http://dx.doi.org/10.7554/eLife.02963 | DOI Listing |
Theriogenology
January 2025
Anhui Province Key Laboratory of Local Livestock and Poultry, Genetical Resource Conservation and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036, China. Electronic address:
Nucleic Acids Res
January 2025
MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Zhejiang University, No.866 Yuhangtang Road, 310058, Hangzhou, China.
Meiosis in mammalian oocytes is interrupted by a prolonged arrest at the germinal vesicle stage, during which oocytes have to repair DNA lesions to ensure genome integrity or otherwise undergo apoptosis. The FIRRM/FLIP-FIGNL1 complex dissociates RAD51 from the joint DNA molecules in both homologous recombination (HR) and DNA replication. However, as a type of non-meiotic, non-replicative cells, whether this RAD51-dismantling mechanism regulates genome integrity in oocytes remains elusive.
View Article and Find Full Text PDFAnimals (Basel)
December 2024
State Key Laboratory of Swine and Poultry Breeding Industry, Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
Retinoic acid (RA) plays a critical role in initiating meiosis in primordial germ cells (PGC), yet the specific mechanisms of its interaction with PGC remain unclear. In this study, we used an in vitro feeder-free culture system with chicken PGC as a model to explore the mechanisms by which RA induces the entry of PGC into meiosis. Results demonstrated that exogenous RA treatment altered the cell cycle distribution of PGC, significantly increasing the proportion of cells in the G1 phase and decreasing those in the G2 phase, suggesting that RA may promote the transition of PGC from proliferation to differentiation.
View Article and Find Full Text PDFGenetics
January 2025
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Bloom Syndrome helicase (Blm) is a RecQ family helicase involved in DNA repair, cell-cycle progression, and development. Pathogenic variants in human BLM cause the autosomal recessive disorder Bloom Syndrome, characterized by predisposition to numerous types of cancer. Prior studies of Drosophila Blm mutants lacking helicase activity or protein have shown sensitivity to DNA damaging agents, defects in repairing DNA double-strand breaks (DSBs), female sterility, and improper segregation of chromosomes in meiosis.
View Article and Find Full Text PDFZhonghua Yi Xue Yi Chuan Xue Za Zhi
January 2025
Department of Obstetrics and Gynecology, the Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, China.
Objective: To explore the genetic characteristics of a Chinese pedigree with rare mosaic 11q partial duplication and its pathogenetic mechanisms.
Methods: A pedigree which underwent prenatal diagnosis at Wenzhou Central Hospital between September 25, 2015 and November 30, 2023 was selected for the study. Clinical data were collected from the pedigree.
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