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Bcl-x(l) Bax interaction after transient global ischemia
F J Antonawich1, S Krajewski, J C Reed
1Department of Neurology and Program in Neurobiology, State University of New York at Stony Brook, 11794-8121, USA.
Summary
Transient ischemia in gerbils causes CA1 neuron death. The protein Bcl-x(long) (Bcl-x(l)) appears neuroprotective, while increased Bax levels promote neuronal death by disrupting Bcl-x(l) interactions.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Transient global ischemia selectively damages CA1 pyramidal neurons in the hippocampus.
- The Bcl-2 protein family regulates apoptosis, but their specific roles in neuronal injury are complex.
- Bcl-2, Bcl-x(long) (Bcl-x(l)), and Bax are key apoptosis-regulating proteins.
Purpose of the Study:
- To investigate the roles of Bcl-2, Bcl-x(l), and Bax in neuronal death following transient ischemia.
- To determine the expression levels and interactions of these proteins in the gerbil hippocampus after carotid occlusion.
Main Methods:
- Bilateral common carotid artery occlusion in Mongolian gerbils to induce transient ischemia.
- Immunoblotting to quantify protein levels of Bcl-2, Bcl-x(l), and Bax.
- Immunoprecipitation to assess protein-protein interactions, specifically Bcl-x(l) and Bax.
Main Results:
- Bcl-x(l) emerged as the primary neuroprotective protein in the gerbil hippocampus, not Bcl-2.
- Bcl-2 and Bcl-x(l) protein levels remained unchanged after ischemia.
- Bax levels significantly increased post-ischemia and its association with Bcl-x(l) was enhanced.
Conclusions:
- Increased Bax levels after ischemia disrupt favorable Bcl-x(l) interactions.
- This disruption by Bax may promote the selective death of CA1 pyramidal neurons during transient ischemic events.
- Bcl-x(l) plays a critical neuroprotective role, but its function is compromised by Bax upregulation.