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Proteolysis of fodrin (non-erythroid spectrin) during apoptosis
S J Martin1, G A O'Brien, W K Nishioka
1Division of Cellular Immunology, La Jolla Institute for Allergy and Immunology, California 92037.
Abstract:
Several recent studies have implicated proteases as important triggers of apoptosis. Thus far, substrates that are cleaved during apoptosis have been elusive. In this report we demonstrate that cleavage of alpha-fodrin (non-erythroid spectrin) accompanies apoptosis, induced by activation via the CD3/T cell receptor complex in a murine T cell hybridoma, ligation of the Fas (CD95) molecule on a human T cell lymphoma line and other Fas-expressing cells, or treatment of cells with staurosporine, dexamethasone, or synthetic ceramide. Furthermore, inhibition of activation-induced apoptosis by pretreatment of T hybridoma cells with antisense oligonucleotides directed against c-myc also inhibited fodrin proteolysis, confirming that this cleavage process is tightly coupled to apoptosis. Fodrin cleavage during apoptosis may have implications for the membrane blebbing seen during this process.
Insights
Proteases trigger apoptosis by cleaving alpha-fodrin (non-erythroid spectrin). This proteolysis is tightly coupled to programmed cell death, potentially explaining membrane blebbing during apoptosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Immunology
Background:
- Proteases are implicated as triggers of apoptosis.
- Substrates cleaved during apoptosis remain largely unidentified.
- Understanding apoptosis pathways is crucial for disease research.
Purpose of the Study:
- To identify substrates cleaved during apoptosis.
- To investigate the role of alpha-fodrin (non-erythroid spectrin) proteolysis in apoptosis.
- To establish the link between c-myc expression and fodrin cleavage during T cell activation-induced apoptosis.
Main Methods:
- Inducing apoptosis via CD3/T cell receptor complex activation, Fas ligation, or chemical treatments (staurosporine, dexamethasone, synthetic ceramide).
- Analyzing alpha-fodrin cleavage in various cell types, including murine T cell hybridoma and human T cell lymphoma lines.
- Utilizing antisense oligonucleotides against c-myc to inhibit apoptosis and assess its effect on fodrin proteolysis.
Main Results:
- Alpha-fodrin (non-erythroid spectrin) cleavage was observed during apoptosis induced by multiple stimuli.
- Fodrin proteolysis was inhibited when activation-induced apoptosis was blocked by c-myc antisense oligonucleotides.
- The cleavage of alpha-fodrin is tightly coupled to the apoptotic process.
Conclusions:
- Alpha-fodrin is a substrate cleaved during apoptosis.
- Fodrin cleavage is a key event linked to programmed cell death.
- This cleavage may contribute to the morphological changes observed during apoptosis, such as membrane blebbing.