Ca2+-CaM Dependent Inactivation of RyR2 Underlies Ca2+ Alternans in Intact Heart
Por:
Wei, JH, Yao, JJ, Belke, D, Guo, WT, Zhong, XW, Sun, B, Wang, RW, Estillore, JP, Vallmitjana, A, Benitez, R, Hove-Madsen, L, Alvarez-Lacalle, E, Echebarria, B, Chen, SRW
Publicada:
19 feb 2021
Resumen:
Rationale:
Ca2+ alternans plays an essential role in cardiac alternans that can lead to ventricular fibrillation, but the mechanism underlying Ca2+ alternans remains undefined. Increasing evidence suggests that Ca2+ alternans results from alternations in the inactivation of cardiac RyR2 (ryanodine receptor 2). However, what inactivates RyR2 and how RyR2 inactivation leads to Ca2+ alternans are unknown.
Objective:
To determine the role of CaM (calmodulin) on Ca2+ alternans in intact working mouse hearts.
Methods and Results:
We used an in vivo local gene delivery approach to alter CaM function by directly injecting adenoviruses expressing CaM-wild type, a loss-of-function CaM mutation, CaM (1-4), and a gain-of-function mutation, CaM-M37Q, into the anterior wall of the left ventricle of RyR2 wild type or mutant mouse hearts. We monitored Ca2+ transients in ventricular myocytes near the adenovirus-injection sites in Langendorff-perfused intact working hearts using confocal Ca2+ imaging. We found that CaM-wild type and CaM-M37Q promoted Ca2+ alternans and prolonged Ca2+ transient recovery in intact RyR2 wild type and mutant hearts, whereas CaM (1-4) exerted opposite effects. Altered CaM function also affected the recovery from inactivation of the L-type Ca2+ current but had no significant impact on sarcoplasmic reticulum Ca2+ content. Furthermore, we developed a novel numerical myocyte model of Ca2+ alternans that incorporates Ca2+-CaM-dependent regulation of RyR2 and the L-type Ca2+ channel. Remarkably, the new model recapitulates the impact on Ca2+ alternans of altered CaM and RyR2 functions under 9 different experimental conditions. Our simulations reveal that diastolic cytosolic Ca2+ elevation as a result of rapid pacing triggers Ca2+-CaM dependent inactivation of RyR2. The resultant RyR2 inactivation diminishes sarcoplasmic reticulum Ca2+ release, which, in turn, reduces diastolic cytosolic Ca2+, leading to alternations in diastolic cytosolic Ca2+, RyR2 inactivation, and sarcoplasmic reticulum Ca2+ release (ie, Ca2+ alternans).
Conclusions:
Our results demonstrate that inactivation of RyR2 by Ca2+-CaM is a major determinant of Ca2+ alternans, making Ca2+-CaM dependent regulation of RyR2 an important therapeutic target for cardiac alternans.
Filiaciones:
Wei, JH:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Yao, JJ:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Belke, D:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Guo, WT:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Zhong, XW:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Sun, B:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Wang, RW:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Estillore, JP:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Vallmitjana, A:
Univ Politecn Cataluna, Dept Automat Control, Barcelona, Spain
Benitez, R:
Univ Politecn Cataluna, Dept Automat Control, Barcelona, Spain
Inst Recerca St Joan Deu IRSJD, Barcelona, Spain
Hove-Madsen, L:
Biomed Res Inst Barcelona IIBB CSIC, Barcelona, Spain
CIBERCV, Barcelona, Spain
Hosp Santa Creu & Sant Pau, IIB St Pau, Barcelona, Spain
Alvarez-Lacalle, E:
Univ Politecn Cataluna, Dept Phys, Barcelona, Spain
Echebarria, B:
Univ Politecn Cataluna, Dept Phys, Barcelona, Spain
Chen, SRW:
Univ Calgary, Libin Cardiovasc Inst, Dept Physiol & Pharmacol, Calgary, AB, Canada
Green Submitted, Bronze
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