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Microfilament assembly is involved in B-cell apoptosis
1Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado, 80206, USA.
Cellular Immunology
|June 29, 1999
Summary
Crosslinking the B-cell antigen receptor (BCR) triggers actin assembly, a crucial step for initiating apoptosis. Inhibiting this process rescues B lymphocytes, revealing the microfilament system
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Crosslinking the B-cell antigen receptor (BCR) initiates signaling pathways leading to cellular responses like cell cycle progression or apoptosis.
- Apoptosis involves significant cellular shape changes, suggesting a role for the cytoskeleton in this process.
Purpose of the Study:
- To investigate the role of actin assembly in BCR-mediated apoptosis.
- To determine if actin polymerization is a prerequisite for initiating apoptosis following BCR crosslinking.
Main Methods:
- Crosslinking of human BCR using anti-IgM antibodies.
- Assessment of actin assembly (G-actin to F-actin conversion).
- Inhibition of actin assembly using botulinum C2 toxin and cytochalasin D.
- Evaluation of tyrosine kinase activation and CPP32 (caspase) activation.
Main Results:
- BCR crosslinking rapidly induced actin assembly.
- Inhibition of G- to F-actin conversion rescued B lymphocytes from apoptosis.
- Prevention of microfilament assembly also inhibited tyrosine kinase and CPP32 (caspase) activation.
Conclusions:
- Actin assembly is a critical, early event in BCR-induced apoptosis.
- Tyrosine phosphorylation appears necessary for both microfilament assembly and apoptosis induction.
- The microfilament system actively participates in signaling pathways that deliver the apoptotic signal.