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Alteration of Cell Cycle Timing and Induction of Surface Instability in Starfish Blastomeres Microinjected with Antibodies to Spectrin

Spectrin has been implicated in a variety of different processes during late embryogenesis, after transcription of the zygotic genome has been activated. However, relatively little is known about the role of maternally derived spectrin during the early cleavage divisions that give rise to a multicel...

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Bibliographic Details
Published in:Developmental biology 1996-11, Vol.180 (1), p.199-212
Main Authors: Wong, Gene K., Hoyle, Duncan H.R., Begg, David A.
Format: Article
Language:English
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Summary:Spectrin has been implicated in a variety of different processes during late embryogenesis, after transcription of the zygotic genome has been activated. However, relatively little is known about the role of maternally derived spectrin during the early cleavage divisions that give rise to a multicellular embryo. To investigate the role of spectrin in early development, we have microinjected anti-spectrin antibodies intoPatiria miniatastarfish embryos to inhibit the activity of the maternal pool of spectrin. Microinjection of affinity-purified anti-spectrin antibody, or low to moderate doses of Fabfragments, into one blastomere of a two-cell-stage embryo caused a dose-dependent, progressive increase in the length of the cell cycle compared to the uninjected control blastomere. The progeny of injected blastomeres were unable to participate in the formation of a blastula epithelium, instead forming a loose aggregate of cells that eventually stopped dividing. When division stopped, the cells formed surface protrusions and became motile. At high doses of either whole antibody or Fabfragments, cells initiated, but failed to complete, cytokinesis. Blastomeres injected with high doses of Fabfragments also failed to reform nuclei and underwent variable periods of cell cycle arrest up to 12 hr. Injected embryos stained with BODIPY-phallacidin exhibited extensive disruption of the cortical actin cytoskeleton. These results support previous studies implicating spectrin in stabilizing the cell surface and maintaining the organization of the cortical cytoskeleton. They further suggest that spectrin is not required for the initiation or contraction of the cleavage furrow, but functions in the completion of cytokinesis. Most surprisingly, however, the results demonstrate that inhibition of spectrin function alters cell cycle timing, suggesting that disruption of the actin cytoskeleton inhibits progression through the cell cycle.
ISSN:0012-1606
1095-564X
DOI:10.1006/dbio.1996.0295