- Email: [email protected]
Changes in Ca2+ transient and contraction of left ventricular papillary muscles in mouse model of dilated cardiomyopathy
ABSTRACTS / Journal of Molecular and Cellular Cardiology 44 (2008) 435–450
441
Purpose: We have found that curcumin inhibits p300, an intrinsic histone acetyltransferase (HAT)-induced acetylation of histones and GATA-4, and represses phenylephrine-induced hypertrophic responses in primary cardiac myocytes from neonatal rats in culture. To determine whether curcumin can prevent the development of heart failure in vivo, we have utilized a salt-sensitive Dahl (DS) rat model of hypertension and myocardial infarction (MI) rat model. Methods: (1) We randomized 11-week-old DS rats with compensated concentric hypertrophy (n = 56) to oral chronic daily treatment with curcumin (50 mg/kg/day) or vehicle. (2) One week after ligation, 32 rats with moderate-sized MI were randomly subjected to treatment with either curcumin (50 mg/ kg/day) or vehicle. Results: At the age of 17 weeks DS rats, curcumin significantly ameliorated the survival rate (curcumin: 76%, vehicle: 44%, p b 0.001). Curcumin treatment preserved LV fractional shortening both in 17-week-old DS rats (curcumin: 48%, vehicle: 31%, p b 0.05) and in MI rats at 7 weeks after ligation (curcumin: 30%, vehicle: 15%, p b 0.0001). Curcumin can suppress increases in acetylation of GATA4 and myocardial cell diameter in rat heats. Conclusion: A natural compound, curcumin, an inhibitor p300-HAT activity, can prevent the development of heart failure in vivo. Thus, this compound might be applicable to heart failure therapy in humans.
light signal as Ca2+ transient (CaT) and isometric tension induced by electrical field stimulation (0.2 Hz, 30 °C). In KI, the amplitude of CaT was significantly increased, whereas the amplitude of tension was significantly deceased compared to those of WT. The time courses of CaT were prolonged and the time courses of tension were shortened in KI. We plotted the relationship between the peak CaT and the peak tension. This relation was shifted to the right in KI, suggesting a decrease in the Ca2+ sensitivity of the myofilament. These results suggest that the altered CaT, in particular the increased peak, in KI could be partly due to the decrease in the Ca2+ sensitivity of the myofilament and the increased intracellular Ca2+ concentration might underlie the cardiac sudden death in this mouse model of DCM.
Keywords: Histone acetyltransferase; p300; Heart failure
Objective: The aim of this study was to examine protein kinases responsible for phosphorylation of glycogen synthase kinase-3β (GSK-3β) in response to cardioprotective signalings and the mechanism by which p-GSK-3β inhibits mitochondrial permeability transition pore (mPTP) opening. Methods: First, tissues for immunoblotting were sampled before and after 25-min global ischemia/5-min reperfusion (I/R) in isolated perfused rat hearts. These timings of sampling were based on our previous finding that anti-infarct tolerance afforded by ischemic preconditioning (PC) and erythropoietin (EPO) correlated with p-GSK-3β level at 5 min after reperfusion. Second, rat hearts underwent I/R with or without PC + EPO infusion (5 U/ml) before ischemia. Results: GSK-3β was translocated from the cytosol to mitochondria after reperfusion, and p-GSK-3β level was increased in all fractions. Reperfusion increased GSK-3β bound to the voltage-dependent anion channel (VDAC) and GSK-3β bound to adenine nucleotide translocase (ANT). The level of this GSK-3β–ANT complex was increased by PC + EPO, though GSK-3β–VDAC complex level was unchanged. ANT but not VADAC was co-immunoprecipitated with p-GSK-3β. Chelerythrine alone and wortmannin alone partially suppressed phosphorylation of GSK-3β bound with ANT by PC + EPO. PKC but not Akt was co-immunoprecipitated with GSK-3β. PC + EPO did not change the level of ANT–VDAC complex but suppressed formation of ANT– cyclophilin-D complex after reperfusion. Conclusion: The results suggest that mitochondrial PKC and cytosolic Akt are responsible for phosphorylation of GSK-3β bound with ANT and that p-GSK-3β achieves
doi:10.1016/j.yjmcc.2007.07.021
O-6. Changes in Ca2+ transient and contraction of left ventricular papillary muscles in mouse model of dilated cardiomyopathy Kenichi Hongo1, Satoshi Morimoto1, Makoto Kawai1, Kimiaki Komukai1, Jin O-Uchi1, Sachio Morimoto2, Satoshi Kurihara1. 1 Jikei University, Tokyo, Japan. 2Kyushu University, Fukuoka, Japan Recently, a number of gene mutations of cardiac contractile proteins have been found to cause familiar cardiomyopathy. Among such mutations, mutations of troponin are frequently observed. Deletion mutant of troponin T (ΔK210) is known to develop dilated cardiomyopathy (DCM) and this mutation causes a decrease in the Ca2+ sensitivity of the myofilament measured in vitro (Morimoto et al., Proc. Natl. Acad. Sci. USA. 2002;99:913–8). In this study, we investigated the changes in Ca2+ handling of the cardiac muscles in knock-in mouse model of this troponin T mutation (KI). KI mice exhibited dilatation of heart chambers and frequently suffered with cardiac sudden death. Papillary muscle preparations were dissected from the left ventricle of KI and wild type (WT) mice (8–10 weeks old) hearts and mounted between a fixed hook and a force transducer. To measure intracellular Ca 2+ concentration, aequorin was micro-injected into the superficial cells of the preparation. We simultaneously measured aequorin
Keywords: Ca2+ handling; Troponin T; Dilated cardiomyopathy doi:10.1016/j.yjmcc.2007.07.022
O-7. GSK-3β phosphorylated by PKC and Akt inhibits ANT–cyclophilin-D interaction: A possible mechanism of cardiomyocyte protection Masahiro Nishihara, Tetsuji Miura, Katsuhiko Ohori, Takayuki Miki, Kazuaki Shimamoto. Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan
441
Purpose: We have found that curcumin inhibits p300, an intrinsic histone acetyltransferase (HAT)-induced acetylation of histones and GATA-4, and represses phenylephrine-induced hypertrophic responses in primary cardiac myocytes from neonatal rats in culture. To determine whether curcumin can prevent the development of heart failure in vivo, we have utilized a salt-sensitive Dahl (DS) rat model of hypertension and myocardial infarction (MI) rat model. Methods: (1) We randomized 11-week-old DS rats with compensated concentric hypertrophy (n = 56) to oral chronic daily treatment with curcumin (50 mg/kg/day) or vehicle. (2) One week after ligation, 32 rats with moderate-sized MI were randomly subjected to treatment with either curcumin (50 mg/ kg/day) or vehicle. Results: At the age of 17 weeks DS rats, curcumin significantly ameliorated the survival rate (curcumin: 76%, vehicle: 44%, p b 0.001). Curcumin treatment preserved LV fractional shortening both in 17-week-old DS rats (curcumin: 48%, vehicle: 31%, p b 0.05) and in MI rats at 7 weeks after ligation (curcumin: 30%, vehicle: 15%, p b 0.0001). Curcumin can suppress increases in acetylation of GATA4 and myocardial cell diameter in rat heats. Conclusion: A natural compound, curcumin, an inhibitor p300-HAT activity, can prevent the development of heart failure in vivo. Thus, this compound might be applicable to heart failure therapy in humans.
light signal as Ca2+ transient (CaT) and isometric tension induced by electrical field stimulation (0.2 Hz, 30 °C). In KI, the amplitude of CaT was significantly increased, whereas the amplitude of tension was significantly deceased compared to those of WT. The time courses of CaT were prolonged and the time courses of tension were shortened in KI. We plotted the relationship between the peak CaT and the peak tension. This relation was shifted to the right in KI, suggesting a decrease in the Ca2+ sensitivity of the myofilament. These results suggest that the altered CaT, in particular the increased peak, in KI could be partly due to the decrease in the Ca2+ sensitivity of the myofilament and the increased intracellular Ca2+ concentration might underlie the cardiac sudden death in this mouse model of DCM.
Keywords: Histone acetyltransferase; p300; Heart failure
Objective: The aim of this study was to examine protein kinases responsible for phosphorylation of glycogen synthase kinase-3β (GSK-3β) in response to cardioprotective signalings and the mechanism by which p-GSK-3β inhibits mitochondrial permeability transition pore (mPTP) opening. Methods: First, tissues for immunoblotting were sampled before and after 25-min global ischemia/5-min reperfusion (I/R) in isolated perfused rat hearts. These timings of sampling were based on our previous finding that anti-infarct tolerance afforded by ischemic preconditioning (PC) and erythropoietin (EPO) correlated with p-GSK-3β level at 5 min after reperfusion. Second, rat hearts underwent I/R with or without PC + EPO infusion (5 U/ml) before ischemia. Results: GSK-3β was translocated from the cytosol to mitochondria after reperfusion, and p-GSK-3β level was increased in all fractions. Reperfusion increased GSK-3β bound to the voltage-dependent anion channel (VDAC) and GSK-3β bound to adenine nucleotide translocase (ANT). The level of this GSK-3β–ANT complex was increased by PC + EPO, though GSK-3β–VDAC complex level was unchanged. ANT but not VADAC was co-immunoprecipitated with p-GSK-3β. Chelerythrine alone and wortmannin alone partially suppressed phosphorylation of GSK-3β bound with ANT by PC + EPO. PKC but not Akt was co-immunoprecipitated with GSK-3β. PC + EPO did not change the level of ANT–VDAC complex but suppressed formation of ANT– cyclophilin-D complex after reperfusion. Conclusion: The results suggest that mitochondrial PKC and cytosolic Akt are responsible for phosphorylation of GSK-3β bound with ANT and that p-GSK-3β achieves
doi:10.1016/j.yjmcc.2007.07.021
O-6. Changes in Ca2+ transient and contraction of left ventricular papillary muscles in mouse model of dilated cardiomyopathy Kenichi Hongo1, Satoshi Morimoto1, Makoto Kawai1, Kimiaki Komukai1, Jin O-Uchi1, Sachio Morimoto2, Satoshi Kurihara1. 1 Jikei University, Tokyo, Japan. 2Kyushu University, Fukuoka, Japan Recently, a number of gene mutations of cardiac contractile proteins have been found to cause familiar cardiomyopathy. Among such mutations, mutations of troponin are frequently observed. Deletion mutant of troponin T (ΔK210) is known to develop dilated cardiomyopathy (DCM) and this mutation causes a decrease in the Ca2+ sensitivity of the myofilament measured in vitro (Morimoto et al., Proc. Natl. Acad. Sci. USA. 2002;99:913–8). In this study, we investigated the changes in Ca2+ handling of the cardiac muscles in knock-in mouse model of this troponin T mutation (KI). KI mice exhibited dilatation of heart chambers and frequently suffered with cardiac sudden death. Papillary muscle preparations were dissected from the left ventricle of KI and wild type (WT) mice (8–10 weeks old) hearts and mounted between a fixed hook and a force transducer. To measure intracellular Ca 2+ concentration, aequorin was micro-injected into the superficial cells of the preparation. We simultaneously measured aequorin
Keywords: Ca2+ handling; Troponin T; Dilated cardiomyopathy doi:10.1016/j.yjmcc.2007.07.022
O-7. GSK-3β phosphorylated by PKC and Akt inhibits ANT–cyclophilin-D interaction: A possible mechanism of cardiomyocyte protection Masahiro Nishihara, Tetsuji Miura, Katsuhiko Ohori, Takayuki Miki, Kazuaki Shimamoto. Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan