Rad52 is well known as a key factor in homologous recombination. Here, we report that Rad52 has functions unrelated to homologous recombination in ; it plays a role in the recruitment of Mps1 to the kinetochores and the maintenance of spindle assembly checkpoint (SAC) activity. Deletion of causes various phenotypes related to the dysregulation of chromosome biorientation. Rad52 directly affects efficient operation of the SAC and accurate chromosome segregation. Remarkably, by using an in vitro kinase assay, we found that Rad52 is a substrate of Ipl1/Aurora and Mps1 in yeast and humans. Ipl1-dependent phosphorylation of Rad52 facilitates the kinetochore accumulation of Mps1, and Mps1-dependent phosphorylation of Rad52 is important for the accurate regulation of the SAC under spindle damage conditions. Taken together, our data provide detailed insights into the regulatory mechanism of chromosome biorientation by mitotic kinases.
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http://dx.doi.org/10.1073/pnas.1705261114 | DOI Listing |
Cytoplasmic dynein is an essential microtubule motor protein that powers organelle transport and mitotic spindle assembly. Its activity depends on dynein-dynactin-cargo adaptor complexes, such as dynein-dynactin-BicD2 (DDB), which typically function with two dynein motors. We show that mechanical tension recruits a third dynein motor via an auxiliary BicD adaptor binding the light intermediate chain of the third dynein, stabilizing multi-dynein assemblies and enhancing force generation.
View Article and Find Full Text PDFBiol Open
January 2025
Manipal Institute of Regenerative Medicine, Manipal Academy of Higher Education, Manipal 576104, India.
Chromosomal aneuploidies are a major cause of developmental failure and pregnancy loss. To investigate the possible consequences of aneuploidy on early embryonic development in vitro, we focused on primed pluripotent stem cells that are relatable to the epiblast of post-implantation embryos in vivo. We used human induced pluripotent stem cells (iPSCs) as an epiblast model and altered chromosome numbers by treating with reversine, a small-molecule inhibitor of monopolar spindle 1 kinase (MSP1) that inactivates the spindle assembly checkpoint, which has been strongly implicated in chromosome mis-segregation and aneuploidy generation.
View Article and Find Full Text PDFDevelopment
January 2025
Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
Karyotype instability in the germline leads to infertility. Unlike the female germline, the male germline continuously produces fertile sperm throughout life. Here we present a molecular network responsible for maintaining karyotype stability in the male mouse germline.
View Article and Find Full Text PDFReprod Med Biol
January 2025
Laboratory of Animal Reproduction, Graduate School of Agricultural Sciences Yamagata University Tsuruoka Japan.
Purpose: This study aimed to investigate the molecular mechanisms associated with chromosome segregation errors caused by intrinsic oxidative stress during in vitro oocyte maturation (IVM) using oocytes from -deficient (KO) mice.
Methods: Ovulated or in vitro matured cumulus-cells oocyte complexes (COCs) were collected from wild-type (WT) and KO mice and evaluated chromosome alignment, chromosome segregation, meiotic progression, and BUBR1 and REC8 protein expression levels.
Results: In 21% O IVM, the KO had significantly higher frequencies of chromosome misalignment and segregation errors compared to the WT, and they also reached Germinal Vesicle Break Down (GVBD) and M I stages peak earlier and showed a shorter M I stage residence time compared to the WT.
Nat Struct Mol Biol
January 2025
Department of Reproductive Endocrinology, University Hospital Zurich, University of Zurich, Schlieren, Switzerland.
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