Dwarf open reading frame (DWORF) is a direct activator of the sarcoplasmic reticulum calcium pump SERCA
- University of Alberta, Canada
- Loyola University Chicago, United States
- University of Michigan, United States
Abstract
The sarcoplasmic reticulum calcium pump SERCA plays a critical role in the contraction-relaxation cycle of muscle. In cardiac muscle, SERCA is regulated by the inhibitor phospholamban. A new regulator, dwarf open reading frame (DWORF), has been reported to displace phospholamban from SERCA. Here, we show that DWORF is a direct activator of SERCA, increasing its turnover rate in the absence of phospholamban. Measurement of in-cell calcium dynamics supports this observation and demonstrates that DWORF increases SERCA-dependent calcium reuptake. These functional observations reveal opposing effects of DWORF activation and phospholamban inhibition of SERCA. To gain mechanistic insight into SERCA activation, fluorescence resonance energy transfer experiments revealed that DWORF has a higher affinity for SERCA in the presence of calcium. Molecular modeling and molecular dynamics simulations provide a model for DWORF activation of SERCA, where DWORF modulates the membrane bilayer and stabilizes the conformations of SERCA that predominate during elevated cytosolic calcium.
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Author details
Funding
National Institutes of Health (R01HL092321)
- Seth L Robia
National Institutes of Health (R01HL092321)
- Howard S Young
National Institutes of Health (R01HL143816)
- Seth L Robia
National Institutes of Health (R01HL143816)
- Howard S Young
National Institutes of Health (R01GM120142)
- L Michel Espinoza-Fonseca
National Institutes of Health (R01HL148068)
- L Michel Espinoza-Fonseca
National Institutes of Health (R01HL130231)
- Aleksey V Zima
Natural Sciences and Engineering Research Council of Canada (RGPIN-2016-06478)
- M Joanne Lemieux
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Fisher et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Dwarf open reading frame (DWORF) is a direct activator of the sarcoplasmic reticulum calcium pump SERCA
eLife 10:e65545.
https://doi.org/10.7554/eLife.65545
