Error-prone chromosome-mediated spindle assembly favors chromosome segregation defects in human oocytes
Science 5 June 2015, Vol. 348 no. 6239 pp. 1143-1147
Zuzana Holubcová1,  Martyn Blayney, Kay Elder, Melina Schuh1,
Author(s) affiliation:
1Medical Research Council, Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
2Bourn Hall Clinic, Bourn, Cambridge CB23 2TN, UK.


Short description:
Most of our knowledge about meiosis in mammalian oocytes stems from studies of mouse oocytes. However, chromosome segregation in mouse oocytes is much more reliable than in human oocytes. Working with the clinic that first pioneered IVF, Holubcové et al. studied freshly harvested human oocytes. They used high-resolution fluorescence microscopy to watch more than 100 human oocytes as they went through each step of meiosis.
Link to the journal


Abstract taken from PubMed

Aneuploidy in human eggs is the leading cause of pregnancy loss and several genetic disorders such as Down syndrome. Most aneuploidy results from chromosome segregation errors during the meiotic divisions of an oocyte, the egg's progenitor cell. The basis for particularly error-prone chromosome segregation in human oocytes is not known. We analyzed meiosis in more than 100 live human oocytes and identified an error-prone chromosome-mediated spindle assembly mechanism as a major contributor to chromosome segregation defects. Human oocytes assembled a meiotic spindle independently of either centrosomes or other microtubule organizing centers. Instead, spindle assembly was mediated by chromosomes and the small guanosine triphosphatase Ran in a process requiring ~16 hours. This unusually long spindle assembly period was marked by intrinsic spindle instability and abnormal kinetochore-microtubule attachments, which favor chromosome segregation errors and provide a possible explanation for high rates of aneuploidy in human eggs.
Copyright © 2015, American Association for the Advancement of Science.
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