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Updated: Jun 1, 2026
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Generation of Transgenic Hydra by Embryo Microinjection
Published on: September 11, 2014
Hydra and the evolution of apoptosis
Charles N David1, Nikola Schmidt, Marsha Schade
1Department Biologie II, Ludwig-Maximilians-University, Munich, Germany.
Integrative and Comparative Biology
|June 17, 2011
Summary
Programmed cell death, or apoptosis, is crucial for animal development and health. In Hydra, caspases initiate apoptosis from mitochondria, and PI3-kinase inhibitors stimulate this process, suggesting conserved growth factor control.
Area of Science:
- Evolutionary biology
- Cellular biology
- Developmental biology
Background:
- Programmed cell death, known as apoptosis, is a fundamental biological process essential for development, tissue homeostasis, and defense across many life forms.
- Apoptosis, characterized by conserved cysteine proteases called caspases, plays a critical role in animals, involving rapid cell death and subsequent phagocytosis of cell corpses.
- Recent findings indicate apoptosis occurs in early metazoan phyla like Cnidaria and Porifera, suggesting an ancient evolutionary origin.
Purpose of the Study:
- To review the role of apoptosis in cnidarians.
- To investigate the subcellular localization of caspases in Hydra.
- To explore the regulatory mechanisms controlling apoptosis in Hydra, particularly the influence of PI3-kinase signaling.
Main Methods:
- Immunocytochemistry was employed to determine the subcellular localization of caspases in Hydra.
- Apoptosis was induced in Hydra to observe caspase activation and release.
- Inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) were used to assess their effect on apoptosis induction.
Main Results:
- Caspases in Hydra were found to be localized within mitochondria.
- Upon apoptosis induction, caspases are released from mitochondria as inactive proenzymes and subsequently activated in the cytoplasm.
- Inhibition of PI3-kinase significantly stimulated apoptosis in Hydra.
Conclusions:
- Caspase activation in Hydra involves mitochondrial release and cytoplasmic processing, a mechanism conserved in apoptosis.
- The observed stimulation of apoptosis by PI3-kinase inhibitors suggests that growth factor signaling pathways regulating apoptosis are evolutionarily conserved from early metazoans.
- These findings provide insights into the evolutionary history and conserved regulatory mechanisms of programmed cell death.
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01:24Caspases
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