Dewenter, Matthias and Seitz, Tilmann and Steinbrecher, Julia H. and Westenbrink, B. Daan and Ling, Haiyun and Lehnart, Stephan E. and Wehrens, Xander H. T. and Backs, Johannes and Brown, Joan Heller and Maier, Lars S. and Neef, Stefan (2024) Ca2+/calmodulin-dependent kinase IIδC-induced chronic heart failure does not depend on sarcoplasmic reticulum Ca2+ leak. ESC HEART FAILURE, 11 (4). pp. 2191-2199. ISSN 2055-5822,
Full text not available from this repository. (Request a copy)Abstract
Aims Hyperactivity of Ca2+/calmodulin-dependent protein kinase II (CaMKII) has emerged as a central cause of pathologic remodelling in heart failure. It has been suggested that CaMKII-induced hyperphosphorylation of the ryanodine receptor 2 (RyR2) and consequently increased diastolic Ca2+ leak from the sarcoplasmic reticulum (SR) is a crucial mechanism by which increased CaMKII activity leads to contractile dysfunction. We aim to evaluate the relevance of CaMKII-dependent RyR2 phosphorylation for CaMKII-induced heart failure development in vivo. Methods and results We crossbred CaMKII delta C overexpressing [transgenic (TG)] mice with RyR2-S2814A knock-in mice that are resistant to CaMKII-dependent RyR2 phosphorylation. Ca2+-spark measurements on isolated ventricular myocytes confirmed the severe diastolic SR Ca2+ leak previously reported in CaMKII delta C TG [4.65 +/- 0.73 mF/F-0 vs. 1.88 +/- 0.30 mF/F-0 in wild type (WT)]. Crossing in the S2814A mutation completely prevented SR Ca2+-leak induction in the CaMKII delta C TG, both regarding Ca2+-spark size and frequency, demonstrating that the CaMKII delta C-induced SR Ca2+ leak entirely depends on the CaMKII-specific RyR2-S2814 phosphorylation. Yet, the RyR2-S2814A mutation did not affect the massive contractile dysfunction (ejection fraction = 12.17 +/- 2.05% vs. 45.15 +/- 3.46% in WT), cardiac hypertrophy (heart weight/tibia length = 24.84 +/- 3.00 vs. 9.81 +/- 0.50 mg/mm in WT), or severe premature mortality (median survival of 12 weeks) associated with cardiac CaMKII delta C overexpression. In the face of a prevented SR Ca2+ leak, the phosphorylation status of other critical CaMKII downstream targets that can drive heart failure, including transcriptional regulator histone deacetylase 4, as well as markers of pathological gene expression including Xirp2, Il6, and Col1a1, was equally increased in hearts from CaMKII delta C TG on a RyR WT and S2814A background. Conclusions S2814 phosphoresistance of RyR2 prevents the CaMKII-dependent SR Ca2+ leak induction but does not prevent the cardiomyopathic phenotype caused by enhanced CaMKII delta C activity. Our data indicate that additional mechanisms-independent of SR Ca2+ leak-are critical for the maladaptive effects of chronically increased CaMKII delta C activity with respect to heart failure.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PROTEIN-KINASE; CAMKII-DELTA; CARDIAC-HYPERTROPHY; DILATED CARDIOMYOPATHY; PRESSURE-OVERLOAD; PHOSPHORYLATION; ISOFORM; OVEREXPRESSION; INHIBITION; NUCLEAR; Ca2+/calmodulin-dependent kinase II; Ryanodine receptor 2; SR Ca2+ leak; Heart failure |
| Subjects: | 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Innere Medizin II |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Jan 2026 06:59 |
| Last Modified: | 14 Jan 2026 06:59 |
| URI: | https://pred.uni-regensburg.de/id/eprint/64980 |
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