scholarly journals Actin protects mammalian eggs against chromosome segregation errors

Science ◽  
2017 ◽  
Vol 357 (6353) ◽  
pp. eaal1647 ◽  
Author(s):  
Binyam Mogessie ◽  
Melina Schuh
2021 ◽  
Vol 134 (7) ◽  

ABSTRACT Binyam Mogessie was born and raised in Ethiopia. He moved to Germany in 2004, where he studied biochemistry and cell biology at Jacobs University Bremen. He then moved to the UK for his PhD with Anne Straube, first at the Marie Curie Research Institute in Surrey and later at the Centre for Mechanochemical Cell Biology in Warwick, where he investigated the cellular mechanisms that organise the microtubule cytoskeleton during skeletal muscle differentiation. After receiving his PhD in cell biology from the University of London, he joined the laboratory of Melina Schuh in 2012 as a postdoc at the MRC-LMB in Cambridge (and later at the Max Planck Institute in Göttingen, Germany), where he discovered a function of the actin cytoskeleton in accurate chromosome segregation and the prevention of aneuploidy in mammalian eggs. Binyam established his independent research laboratory at the University of Bristol, School of Biochemistry in 2018, where he is a Wellcome Trust and Royal Society Sir Henry Dale fellow and HFSP Young Investigator. He also received a Seed Award from the Wellcome Trust and funding from the Rosetrees Trust and Royal Society. His lab is investigating actin- and microtubule-based cytoskeletal ensembles that promote healthy egg development and embryogenesis in mammals.


Author(s):  
Carolyn A. Larabell ◽  
David G. Capco ◽  
G. Ian Gallicano ◽  
Robert W. McGaughey ◽  
Karsten Dierksen ◽  
...  

Mammalian eggs and embryos contain an elaborate cytoskeletal network of “sheets” which are distributed throughout the entire cell cytoplasm. Cytoskeletal sheets are long, planar structures unlike the cytoskeletal networks typical of somatic cells (actin filaments, microtubules, and intermediate filaments), which are filamentous. These sheets are not found in mammalian somatic cells nor are they found in nonmammalian eggs or embryos. Evidence that they are, indeed, cytoskeletal in nature is derived from studies demonstrating that 1) the sheets are retained in the detergent-resistant cytoskeleton fraction; 2) there are no associated membranes (determined by freeze-fracture); and 3) the sheets dissociate into filaments at the blastocyst stage of embryogenesis. Embedment-free sections of hamster eggs viewed at 60 kV show sheets running across the egg cytoplasm (Fig. 1). Although this approach provides excellent global views of the sheets and their reorganization during development, the mechanism of image formation for embedment-free sections does not permit evaluation of the sheets at high resolution.


2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.


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