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Shifting meiotic to mitotic spindle assembly in oocytes disrupts chromosome alignment
Author(s) -
Bennabi Isma,
Quéguiner Isabelle,
Kolano Agnieszka,
Boudier Thomas,
Mailly Philippe,
Verlhac MarieHélène,
Terret MarieEmilie
Publication year - 2018
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.201745225
Subject(s) - meiosis , microbiology and biotechnology , spindle apparatus , spindle pole body , multipolar spindles , biology , microtubule organizing center , chromosome segregation , centrosome , mitosis , centriole , microtubule , genetics , cell division , chromosome , cell cycle , gene , cell
Mitotic spindles assemble from two centrosomes, which are major microtubule‐organizing centers ( MTOC s) that contain centrioles. Meiotic spindles in oocytes, however, lack centrioles. In mouse oocytes, spindle microtubules are nucleated from multiple acentriolar MTOC s that are sorted and clustered prior to completion of spindle assembly in an “inside‐out” mechanism, ending with establishment of the poles. We used HSET (kinesin‐14) as a tool to shift meiotic spindle assembly toward a mitotic “outside‐in” mode and analyzed the consequences on the fidelity of the division. We show that HSET levels must be tightly gated in meiosis I and that even slight overexpression of HSET forces spindle morphogenesis to become more mitotic‐like: rapid spindle bipolarization and pole assembly coupled with focused poles. The unusual length of meiosis I is not sufficient to correct these early spindle morphogenesis defects, resulting in severe chromosome alignment abnormalities. Thus, the unique “inside‐out” mechanism of meiotic spindle assembly is essential to prevent chromosomal misalignment and production of aneuploidy gametes.