151. A Role for Rho-like GTPases in the Polarisation of Mouse Eight-Cell Blastomeres
- Author
-
Lesley Clayton, Martin H. Johnson, and Alan Hall
- Subjects
Blastomeres ,Botulinum Toxins ,Cytochalasin D ,Microinjections ,preimplantation mouse conceptus ,Cell Cycle Proteins ,Mice, Inbred Strains ,GTPase ,Pregnancy Proteins ,Biology ,Microfilament ,Morula ,GTP Phosphohydrolases ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Rho ,GTP-Binding Proteins ,Cell polarity ,Cell Adhesion ,Animals ,Humans ,compaction ,polarity ,cdc42 GTP-Binding Protein ,Cytoskeleton ,Cell adhesion ,Molecular Biology ,Body Patterning ,030304 developmental biology ,ADP Ribose Transferases ,cdc42 GTP-Binding Protein, Saccharomyces cerevisiae ,0303 health sciences ,Cell adhesion molecule ,Cell Polarity ,cytoskeleton ,Cell Biology ,Cadherins ,Actin cytoskeleton ,Rho Factor ,Cell biology ,adhesion ,Cdc42 GTP-Binding Protein ,microfilaments ,Female ,030217 neurology & neurosurgery ,Developmental Biology - Abstract
Polarisation of cells during mouse preimplantation development first occurs within blastomeres at the eight-cell stage, as part of a process called compaction. Cell–cell contact mediated by the cell adhesion molecule uvomorulin (E-cadherin) and the activity of the microfilament cytoskeleton are important in the development of compaction, which is crucial for establishment of trophoblast and pluriblast (inner cell mass) lineages and for subsequent development. Members of the Rho family of p21 GTPases have been shown to regulate the organisation of the actin cytoskeleton and adhesion in other cell types. The potential role of these proteins in compaction was investigated. Inhibition of Rho withClostridium botulinumC3-transferase disturbed intercellular flattening at compaction and prevented cytocortical microfilament polarisation of eight-cell blastomeres, in contrast to cytochalasin D which inhibited only adhesion. Microinjection of a constitutively activated recombinant Rho protein into four-cell blastomeres induced cortical microfilament disruption and apical displacement of nuclei associated with polarised clustering of microtubules. Interblastomere adhesion was reduced and E-cadherin was aberrently clustered at remaining cell–cell contacts. Similarly, activated Cdc42 protein induced nuclear displacement with additional cytoplasmic actin bundle formation between nucleus and cell–cell contacts. The effects produced by both of the activated GTPase proteins are indicative of prematurely induced but aberrently organised polarity. These results suggest that Rho family GTPases are involved in the polarisation of early mouse blastomeres.
- Published
- 1999