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Apoptosis in motion. An apical, P35-insensitive caspase mediates programmed cell death in insect cells
1Institute for Molecular Virology, and Department of Biochemistry, Graduate School and College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA.
The Journal of Biological Chemistry
|March 30, 2001
Summary
Insect apoptosis involves a caspase cascade. Researchers identified a novel caspase mediating the activation of Sf-caspase-1, crucial for programmed cell death in Spodoptera frugiperda cells.
Area of Science:
- Cell Biology
- Molecular Biology
- Insect Physiology
Background:
- Caspase activation via proteolytic processing is essential for apoptosis in multicellular organisms.
- Understanding caspase cascades in insects provides insights into conserved cell death pathways.
Purpose of the Study:
- To investigate the link between caspase activation and apoptotic morphology in insect cells.
- To identify the initiator caspases responsible for activating the principal effector caspase, Sf-caspase-1.
Main Methods:
- High-resolution time-lapse microscopy of cultured Spodoptera frugiperda (SF21) cells.
- Utilizing cell-permeable peptide inhibitors to study pro-Sf-caspase-1 processing.
- Assessing the effects of specific caspase inhibitors (IETD-fmk, IETD-CHO) and apoptosis inhibitors (Op-IAP, P35).
Main Results:
- Caspase activation tightly correlated with morphological changes during apoptosis in SF21 cells.
- The effector caspase Sf-caspase-1 was proteolytically activated during apoptosis.
- A novel, P35-resistant caspase was identified as responsible for the initial processing of pro-Sf-caspase-1, distinct from the protease inhibited by IETD-CHO.
Conclusions:
- Apoptosis in insects, like mammals, proceeds through a caspase activation cascade.
- A previously unknown apical caspase initiates the activation of Sf-caspase-1, independent of P35 inhibition.
- This discovery advances the understanding of conserved apoptotic pathways across metazoans.