Increase of intracellular Ca2+ and relocation of E-cadherin during experimental decompaction of mouse embryos.
To determine the role of intracellular Ca2+ in compaction, the first morphogenetic event in embryogenesis, we analyzed preimplantation mouse embryos under several decompacting conditions, including depletion of extracellular Ca2+, blocking of Ca2+ channels, and inhibition of microfilaments, calmodulin, and intracellular Ca2+ release. Those treatments induced decompaction of mouse morulae and simultaneously induced changes in cytosolic free Ca2+ concentration and deregionalization of E-cadherin and fodrin. When morulae were allowed to recompact, the location of both proteins recovered. In contrast, actin did not change its cortical location with compaction nor with decompaction-recompaction. Calmodulin localized in areas opposite to cell-cell contacts in eight-cell stage embryos before and after compaction. Inhibition of calmodulin with trifluoperazine induced its delocalization while morulae decompacted. A nonspecific rise of intracellular free Ca2+ provoked by ionomycin did not affect the compacted shape. Moreover, the same decompacting treatments when applied to uncompacted embryos did not produce any change in intracellular Ca2+. Our results demonstrate that in preimplantation mouse embryos experimentally induced stage-specific changes of cell shape are accompanied by changes of intracellular free Ca2+ and redistribution of the cytoskeleton-related proteins E-cadherin, fodrin, and calmodulin. We conclude that intracellular Ca2+ specifically is involved in compaction and probably regulates the function and localization of cytoskeleton elements.
Pey
R
R
Departamento de Biologia, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
Vial
C
C
Schatten
G
G
Hafner
M
M
D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D015820:Cadherins / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002352:Carrier Proteins / Q000502:physiology; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D006063:Chorionic Gonadotropin / Q000502:physiology; D015638:Cytochalasin D / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005314:Embryonic and Fetal Development; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D008840:Microfilament Proteins / Q000502:physiology; D018613:Microscopy, Confocal; D009024:Morphogenesis / Q000502:physiology*; D009028:Morula / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014268:Trifluoperazine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D015044:Zona Pellucida / Q000502:physiology; D013049:Spectrin
D015820:Cadherins; D002118:Calcium; D002147:Calmodulin; D002352:Carrier Proteins; D006063:Chorionic Gonadotropin; D015638:Cytochalasin D; D004533:Egtazic Acid; D008565:Membrane Proteins; D008840:Microfilament Proteins; D014268:Trifluoperazine; D014700:Verapamil; D013049:Spectrin