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Dantrolene stabilizes domain interactions within the ryanodine receptor
Shigeki Kobayashi1, Mark L Bannister, Jaya P Gangopadhyay
1Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
The Journal of Biological Chemistry
|December 22, 2004
Summary
Dantrolene stabilizes skeletal muscle ryanodine receptor-1 channel interactions, preventing malignant hyperthermia-related dysfunction. This mechanism involves stabilizing the domain switch, crucial for calcium channel regulation.
Area of Science:
- Biophysics
- Molecular Biology
- Pharmacology
Background:
- Skeletal muscle ryanodine receptor-1 (RyR1) Ca(2+) channel regulation involves interdomain interactions forming a "domain switch."
- Malignant hyperthermia (MH) is linked to domain switch instability, causing RyR1 channel dysfunction.
- Dantrolene, an MH therapeutic, targets the RyR1 domain switch region.
Purpose of the Study:
- To investigate the mechanism of action of dantrolene on RyR1 channel function.
- To determine how dantrolene affects domain unzipping and channel activation.
Main Methods:
- Utilized a fluorescence probe (methylcoumarin acetate) attached to the RyR1 domain switch via peptide DP4.
- Measured domain unzipping using fluorescence quenching by a macromolecular quencher.
- Assessed RyR1 channel activation via [(3)H]ryanodine binding and Ca(2+) release from sarcoplasmic reticulum.
Main Results:
- DP4 peptide and anti-DP4 antibody increased domain unzipping, indicated by increased Stern-Volmer quenching constant (K(Q)).
- Dantrolene reversed DP4/anti-DP4-induced domain unzipping at both 37°C and 22°C.
- DP4 enhanced RyR1 activation, while dantrolene inhibited this activation at 37°C, with calmodulin involvement at 22°C.
Conclusions:
- Dantrolene stabilizes domain-domain interactions within the RyR1 domain switch, preventing dysfunction.
- Temperature and calmodulin modulate the coupling between the RyR1 domain switch and Ca(2+) channel opening, not the switch itself.