1. Engineered calmodulins reveal the unexpected eminence of Ca2+ channel inactivation in controlling heart excitation.
- Author
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Alseikhan BA, DeMaria CD, Colecraft HM, and Yue DT
- Subjects
- Action Potentials drug effects, Adenoviridae genetics, Animals, Guinea Pigs, Heart physiology, Rats, Recombinant Proteins pharmacology, Calcium Channels, L-Type drug effects, Calmodulin pharmacology, Heart drug effects, Protein Engineering
- Abstract
Engineered calmodulins (CaMs), rendered Ca2+-insensitive by mutations, function as dominant negatives in heterologous systems, and have revealed mechanisms of ion channel modulation by Ca2+/CaM. The use of these CaMs in native mammalian cells now emerges as a strategy to unmask the biology of such Ca2+ feedback. Here, we developed recombinant adenoviruses bearing engineered CaMs to facilitate their expression in adult heart cells, where Ca2+ regulation may be essential for moment-to-moment control of the heartbeat. Engineered CaMs not only eliminated the Ca2+-dependent inactivation of native calcium channels, but exposed an unexpectedly large impact of removing such feedback: the unprecedented (4- to 5-fold) prolongation of action potentials. This striking result recasts the basic paradigm for action-potential control and illustrates the promise of virally delivered engineered CaM to investigate the biology of numerous other CaM-signaling pathways.
- Published
- 2002
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