Different routes lead to apoptosis in unfertilized sea urchin eggs
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Results obtained in various species, from mammals to invertebrates, show that arrest in the cell cycle of mature oocytes is due to a high ERK activity. Apoptosis is stimulated in these oocytes if fertilization does not occur. Our previous data suggest that apoptosis of unfertilized sea urchin eggs is the consequence of an aberrant short attempt of development that occurs if ERK is inactivated. They contradict those obtained in starfish, another echinoderm, where inactivation of ERK delays apoptosis of aging mature oocytes that are nevertheless arrested at G1 of the cell cycle as in the sea urchin. This suggests that the cell death pathway that can be activated in unfertilized eggs is not the same in sea urchin and in starfish. In the present study, we find that protein synthesis is necessary for the survival of unfertilized sea urchin eggs, contrary to starfish. We also compare the effects induced by Emetine, an inhibitor of protein synthesis, with those triggered by Staurosporine, a non specific inhibitor of protein kinase that is widely used to induce apoptosis in many types of cells. Our results indicate that the unfertilized sea urchin egg contain different mechanisms capable of leading to apoptosis and that rely or not on changes in ERK activity, acidity of intracellular organelles or intracellular Ca and pH. We discuss the validity of some methods to investigate cell death such as measurements of caspase activation with the fluorescent caspase indicator FITC-VAD-fmk or acidification of intracellular organelles, methods that may lead to erroneous conclusions at least in the sea urchin model.
KeywordsApoptosis Egg Sea urchin MAP kinase Calcium Staurosporine
We thank R. Dumollard and A. Mc Dougall for their help in Ca measurements and C. Billam for correcting our manuscript.
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- 16.Houel-Renault L, Philippe L, Piquemal M, Ciapa B (2013) Autophagy is used as a survival program in unfertilized sea urchin eggs that are destined to die by apoptosis after inactivation of MAPK1/3 (ERK2/1). Autophagy. 9(10):1527–1539Google Scholar
- 29.Pesando D, Dominice C, Dufour MN, Guillon G, Jouin P, Ciapa B (1995) Effect of nordidemnin on the cell cycle of sea urchin embryos. Role in synthesis and phosphorylation of proteins and in polyphosphoinositide turnover in mitosis progression. Exp Cell Res 220(1):18–28. doi: 10.1006/excr.1287 PubMedCrossRefGoogle Scholar
- 30.Wagenaar EB, Mazia D (1978) In: Dirksen ER, Prescott DM, Fos CF (eds) Cell reproduction, vol 12. Academic Press, New York, pp 539–545Google Scholar