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ABSTRACT Mitosis is a fundamental and highly regulated process that acts to faithfully segregate chromosomes into two identical daughter cells. Localization of gene transcripts involved in mitosis to the mitotic spindle might be an evolutionarily conserved mechanism to ensure that mitosis occurs in a timely manner. We identified many RNA transcripts that encode proteins involved in mitosis localized at the mitotic spindles in dividing sea urchin embryos and mammalian cells. Disruption of microtubule polymerization, kinesin-1 or dynein results in lack of spindle localization of these transcripts in the sea urchin embryo. Furthermore, results indicate that the cytoplasmic polyadenylation element (CPE) within the 3′UTR of the Aurora B transcript, a recognition sequence for CPEB, is essential for RNA localization to the mitotic spindle in the sea urchin embryo. Blocking this sequence results in arrested development during early cleavage stages, suggesting that RNA localization to the mitotic spindle might be a regulatory mechanism of cell division that is important for early development.
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The mitotic protein NuMA plays a spindle-independent role in nuclear formation and mechanics
Eukaryotic cells typically form a single, round nucleus after mitosis, and failures to do so can compromise genomic integrity. How mammalian cells form such a nucleus remains incompletely understood. NuMA is a spindle protein whose disruption results in nuclear fragmentation. What role NuMA plays in nuclear integrity, and whether its perceived role stems from its spindle function, are unclear. Here, we use live imaging to demonstrate that NuMA plays a spindle-independent role in forming a single, round nucleus. NuMA keeps the decondensing chromosome mass compact at mitotic exit and promotes a mechanically robust nucleus. NuMA’s C terminus binds DNA in vitro and chromosomes in interphase, while its coiled-coil acts as a central regulatory and structural element: it prevents NuMA from binding chromosomes at mitosis, regulates its nuclear mobility, and is essential for nuclear formation. Thus, NuMA plays a structural role over the cell cycle, building and maintaining the spindle and nucleus, two of the cell’s largest structures.
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- Award ID(s):
- 1617028
- PAR ID:
- 10284650
- Date Published:
- Journal Name:
- Journal of Cell Biology
- Volume:
- 219
- Issue:
- 12
- ISSN:
- 0021-9525
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1083/jcb.202004202
