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Molecular cloning and identification of murine caspase-8
M Van de Craen1, G Van Loo, W Declercq
1Department of Molecular Biology, Flanders Interuniversity Institute for Biotechnology and University of Ghent, K. L. Ledeganckstraat 35, Ghent, B-9000, Belgium.
Abstract:
Several caspases are mediators of apoptotic cell death. We describe a novel murine member of this growing protein family. Based on homology and especially on the substrate specificity, this new procaspase is identified as the murine counterpart of human procaspase-8. The protein exhibits a rather low similarity (76%) and identity (70%) to human procaspase-8. Procaspase-8 mRNA is expressed in all adult mouse tissues examined, the highest levels being reached in kidney, liver and lung. Procaspase-8 mRNA expression is highest in seven-day old embryos, but also during later stages of development the expression was fairly high. Both human and murine procaspase-8 are very weak substrates for granzyme B as compared to procaspase-3. Murine procaspases-1, 2, 3, 6, 7, 8, 11/4 and 12 are processed by recombinant murine caspase-8, suggesting a key role in the procaspase activation cascade. In addition, murine caspase-8 induced cell death that was inhibited both by cytokine response modifier A and p35. In vitro experiments demonstrated that p35 inhibits caspase-8 directly.
Insights
Researchers identified a novel murine procaspase-8, crucial for apoptosis. This caspase-8 plays a key role in activating other caspases and induces cell death, highlighting its significance in biological processes.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Caspases are key mediators of apoptotic cell death.
- A novel murine protein belonging to the caspase family was identified.
Purpose of the Study:
- To identify and characterize a novel murine caspase, designated murine procaspase-8.
- To investigate the expression pattern and functional role of murine procaspase-8 in apoptosis and caspase activation.
Main Methods:
- Homology analysis and substrate specificity studies were used to identify the novel murine caspase.
- Procaspase-8 mRNA expression was analyzed in various adult mouse tissues and embryonic stages.
- Recombinant murine caspase-8 was used to process other murine caspases in vitro.
- Cell death induced by murine caspase-8 was assessed in the presence of inhibitors.
Main Results:
- The novel murine caspase was identified as the counterpart of human procaspase-8, with 76% similarity and 70% identity.
- Procaspase-8 mRNA is widely expressed in adult mouse tissues, with highest levels in kidney, liver, and lung, and is highly expressed during embryonic development.
- Murine procaspase-8 is a weak substrate for granzyme B compared to procaspase-3.
- Murine caspase-8 processes multiple other murine caspases, indicating a role in the activation cascade.
- Murine caspase-8 induced cell death, which was inhibited by cytokine response modifier A and p35, with p35 directly inhibiting caspase-8.
Conclusions:
- Murine procaspase-8 is a novel caspase with significant homology to human procaspase-8.
- Murine caspase-8 is widely expressed and plays a critical role in the caspase activation cascade, mediating apoptotic cell death.
- The findings provide insights into the regulation of apoptosis in mice and the function of caspase-8.