Heart failure-related hyperphosphorylation in the cardiac troponin I C terminus has divergent effects on cardiac function in vivo
| Autor: | Genaro A. Ramirez-Correa, David A. Kass, Guangshuo Zhu, Pingbo Zhang, Gizem Keceli, Amir S. Heravi, Anne M. Murphy, Nazli Okumus, Cyrus Takahashi, Yuejin Li, Nazareno Paolocci |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Male Time Factors Left Hemodynamics 030204 cardiovascular system & hematology Inbred C57BL Ventricular Function Left Transgenic Mice 0302 clinical medicine Myofibrils Troponin I Serine Ventricular Function Phosphorylation Promoter Regions Genetic Ejection fraction Calpain Protein Stability Adrenergic beta-Agonists Phenotype Cardiology Proteolysis Animals Disease Models Animal Genetic Predisposition to Disease Heart Failure Isolated Heart Preparation Mice Inbred C57BL Mice Transgenic Mutation Myocardial Reperfusion Injury Myosin Heavy Chains Protein Domains Recovery of Function Myocardial Contraction Cardiology and Cardiovascular Medicine Cardiac function curve medicine.medical_specialty Ischemia Hyperphosphorylation Article Promoter Regions 03 medical and health sciences Genetic Internal medicine medicine business.industry Animal medicine.disease 030104 developmental biology Heart failure Disease Models business Reperfusion injury |
| Popis: | Background: In human heart failure, Ser199 (equivalent to Ser200 in mouse) of cTnI (cardiac troponin I) is significantly hyperphosphorylated, and in vitro studies suggest that it enhances myofilament calcium sensitivity and alters calpain-mediated cTnI proteolysis. However, how its hyperphosphorylation affects cardiac function in vivo remains unknown. Methods and Results: To address the question, 2 transgenic mouse models were generated: a phospho-mimetic cTnIS200D and a phospho-silenced cTnIS200A, each driven by the cardiomyocyte-specific α-myosin heavy chain promoter. Cardiac structure assessed by echocardiography and histology was normal in both transgenic models compared with littermate controls (n=5). Baseline in vivo hemodynamics and isolated muscle studies showed that cTnIS200D significantly prolonged relaxation and lowered left ventricular peak filling rate, whereas ejection fraction and force development were normal (n=5). However, with increased heart rate or β-adrenergic stimulation, cTnIS200D mice had less enhanced ejection fraction or force development versus controls, whereas relaxation improved similarly to controls (n=5). By contrast, cTnIS200A was functionally normal both at baseline and under the physiological stresses. To test whether either mutation impacted cardiac response to ischemic stress, isolated hearts were subjected to ischemia/reperfusion. cTnIS200D were protected, recovering 88±8% of contractile function versus 35±15% in littermate controls and 28±8% in cTnIS200A (n=5). This was associated with less cTnI proteolysis in cTnIS200D hearts. Conclusions: Hyperphosphorylation of this serine in cTnI C terminus impacts heart function by depressing diastolic function at baseline and limiting systolic reserve under physiological stresses. However, paradoxically, it preserves heart function after ischemia/reperfusion injury, potentially by decreasing proteolysis of cTnI. |
| Databáze: | OpenAIRE |
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