ZBTB20 Regulates SERCA2a Activity and Myocardial Contractility Through Phospholamban

BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear.Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20flox mice with Myh6-Cre mice. Echocardiography, blood pressure measurements, Langendorff perfusion, histological analysis and immunohistochemistry, quantitative reverse transcription-PCR, Western blot analysis, electrophysiological measurements, and chromatin immunoprecipitation assay were performed to clarify the phenotype and elucidate the molecular mechanisms.Specific ablation of ZBTB20 in cardiomyocyte led to a significant increase in basal myocardial contractile parameters both in vivo and in vitro, accompanied by an impairment in cardiac reserve and exercise capacity. Moreover, the cardiomyocytes lacking ZBTB20 showed an increase in sarcoplasmic reticular Ca2+ content and exhibited a remarkable enhancement in both SERCA2a activity and electrically stimulated contraction. Mechanistically, PLN expression was dramatically reduced in cardiomyocytes at the mRNA and protein levels by ZBTB20 deletion or silencing, and PLN overexpression could largely restore the basal contractility in ZBTB20-deficient cardiomyocytes.These data point to ZBTB20 as a fine-tuning modulator of PLN expression and SERCA2a activity, thereby offering new perspective on the regulation of basal contractility in the mammalian heart.The biological function of ZBTB20 has been increasingly emphasized, but its role in the heart remains unclear. Here we demonstrate a cell-autonomous role of the zinc finger protein ZBTB20 in regulating myocardial SERCA2a activity through PLN. We found that ZBTB20 is highly expressed in cardiomyocytes, and cardiac-specific ZBTB20 knockout mice showed significantly increased in vivo and ex vivo cardiac contractile function. In isolated cardiomyocytes, ZBTB20 knockout resulted in significant increases in contractility, SR Ca2+ content, and SERCA2a activity. Further investigations revealed that ZBTB20 deficiency led to a significant decrease in PLN expression, and replenishing PLN could reverse the hypercontractility of cardiomyocytes caused by ZBTB20 knockout. These results suggest ZBTB20 play a critical role in the regulation of cardiac Ca2+ cycling and contractility primarily through SERCA2a/PLN pathway.BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear.Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20flox mice with Myh6-Cre mice. Echocardiography, blood pressure measurements, Langendorff perfusion, histological analysis and immunohistochemistry, quantitative reverse transcription-PCR, Western blot analysis, electrophysiological measurements, and chromatin immunoprecipitation assay were performed to clarify the phenotype and elucidate the molecular mechanisms. Specific ablation of ZBTB20 in cardiomyocyte led to a significant increase in basal myocardial contractile parameters both in vivo and in vitro, accompanied by an impairment in cardiac reserve and exercise capacity. Moreover, the cardiomyocytes lacking ZBTB20 showed an increase in sarcoplasmic reticular Ca2+ content and exhibited a remarkable enhancement in both SERCA2a activity and electrically stimulated contraction. Mechanistically, PLN expression was dramatically reduced in cardiomyocytes at the mRNA and protein levels by ZBTB20 deletion or silencing, and PLN overexpression could largely restore the basal contractility in ZBTB20-deficient cardiomyocytes.These data point to ZBTB20 as a fine-tuning modulator of PLN expression and SERCA2a activity, thereby offering new perspective on the regulation of basal contractility in the mammalian heart.The biological function of ZBTB20 has been increasingly emphasized, but its role in the heart remains unclear. Here we demonstrate a cell-autonomous role of the zinc finger protein ZBTB20 in regulating myocardial SERCA2a activity through PLN. We found that ZBTB20 is highly expressed in cardiomyocytes, and cardiac-specific ZBTB20 knockout mice showed significantly increased in vivo and ex vivo cardiac contractile function. In isolated cardiomyocytes, ZBTB20 knockout resulted in significant increases in contractility, SR Ca2+ content, and SERCA2a activity. Further investigations revealed that ZBTB20 deficiency led to a significant decrease in PLN expression, and replenishing PLN could reverse the hypercontractility of cardiomyocytes caused by ZBTB20 knockout. These results suggest ZBTB20 play a critical role in the regulation of cardiac Ca2+ cycling and contractility primarily through SERCA2a/PLN pathway.BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear.Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20flox mice with Myh6-Cre mice. Echocardiography, blood pressure measurements, Langendorff perfusion, histological analysis and immunohistochemistry, quantitative reverse transcription-PCR, Western blot analysis, electrophysiological measurements, and chromatin immunoprecipitation assay were performed to clarify the phenotype and elucidate the molecular mechanisms.Specific ablation of ZBTB20 in cardiomyocyte led to a significant increase in basal myocardial contractile parameters both in vivo and in vitro, accompanied by an impairment in cardiac reserve and exercise capacity. Moreover, the cardiomyocytes lacking ZBTB20 showed an increase in sarcoplasmic reticular Ca2+ content and exhibited a remarkable enhancement in both SERCA2a activity and electrically stimulated contraction. Mechanistically, PLN expression was dramatically reduced in cardiomyocytes at the mRNA and protein levels by ZBTB20 deletion or silencing, and PLN overexpression could largely restore the basal contractility in ZBTB20-deficient cardiomyocytes.These data point to ZBTB20 as a fine-tuning modulator of PLN expression and SERCA2a activity, thereby offering new perspective on the regulation of basal contractility in the mammalian heart. The biological function of ZBTB20 has been increasingly emphasized, but its role in the heart remains unclear. Here we demonstrate a cell-autonomous role of the zinc finger protein ZBTB20 in regulating myocardial SERCA2a activity through PLN. We found that ZBTB20 is highly expressed in cardiomyocytes, and cardiac-specific ZBTB20 knockout mice showed significantly increased in vivo and ex vivo cardiac contractile function. In isolated cardiomyocytes, ZBTB20 knockout resulted in significant increases in contractility, SR Ca2+ content, and SERCA2a activity. Further investigations revealed that ZBTB20 deficiency led to a significant decrease in PLN expression, and replenishing PLN could reverse the hypercontractility of cardiomyocytes caused by ZBTB20 knockout. These results suggest ZBTB20 play a critical role in the regulation of cardiac Ca2+ cycling and contractility primarily through SERCA2a/PLN pathway.BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear.Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20flox mice with Myh6-Cre mice. Echocardiography, blood pressure measurements, Langendorff perfusion, histological analysis and immunohistochemistry, quantitative reverse transcription-PCR, Western blot analysis, electrophysiological measurements, and chromatin immunoprecipitation assay were performed to clarify the phenotype and elucidate the molecular mechanisms.Specific ablation of ZBTB20 in cardiomyocyte led to a significant increase in basal myocardial contractile parameters both in vivo and in vitro, accompanied by an impairment in cardiac reserve and exercise capacity. Moreover, the cardiomyocytes lacking ZBTB20 showed an increase in sarcoplasmic reticular Ca2+ content and exhibited a remarkable enhancement in both SERCA2a activity and electrically stimulated contraction. Mechanistically, PLN expression was dramatically reduced in cardiomyocytes at the mRNA and protein levels by ZBTB20 deletion or silencing, and PLN overexpression could largely restore the basal contractility in ZBTB20-deficient cardiomyocytes.These data point to ZBTB20 as a fine-tuning modulator of PLN expression and SERCA2a activity, thereby offering new perspective on the regulation of basal contractility in the mammalian heart.The biological function of ZBTB20 has been increasingly emphasized, but its role in the heart remains unclear. Here we demonstrate a cell-autonomous role of the zinc finger protein ZBTB20 in regulating myocardial SERCA2a activity through PLN. We found that ZBTB20 is highly expressed in cardiomyocytes, and cardiac-specific ZBTB20 knockout mice showed significantly increased in vivo and ex vivo cardiac contractile function. In isolated cardiomyocytes, ZBTB20 knockout resulted in significant increases in contractility, SR Ca2+ content, and SERCA2a activity. Further investigations revealed that ZBTB20 deficiency led to a significant decrease in PLN expression, and replenishing PLN could reverse the hypercontractility of cardiomyocytes caused by ZBTB20 knockout. These results suggest ZBTB20 play a critical role in the regulation of cardiac Ca2+ cycling and contractility primarily through SERCA2a/PLN pathway. BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear.Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20flox mice with Myh6-Cre mice. Echocardiography, blood pressure measurements, Langendorff perfusion, histological analysis and immunohistochemistry, quantitative reverse transcription-PCR, Western blot analysis, electrophysiological measurements, and chromatin immunoprecipitation assay were performed to clarify the phenotype and elucidate the molecular mechanisms.Specific ablation of ZBTB20 in cardiomyocyte led to a significant increase in basal myocardial contractile parameters both in vivo and in vitro, accompanied by an impairment in cardiac reserve and exercise capacity. Moreover, the cardiomyocytes lacking ZBTB20 showed an increase in sarcoplasmic reticular Ca2+ content and exhibited a remarkable enhancement in both SERCA2a activity and electrically stimulated contraction. Mechanistically, PLN expression was dramatically reduced in cardiomyocytes at the mRNA and protein levels by ZBTB20 deletion or silencing, and PLN overexpression could largely restore the basal contractility in ZBTB20-deficient cardiomyocytes.These data point to ZBTB20 as a fine-tuning modulator of PLN expression and SERCA2a activity, thereby offering new perspective on the regulation of basal contractility in the mammalian heart.The biological function of ZBTB20 has been increasingly emphasized, but its role in the heart remains unclear. Here we demonstrate a cell-autonomous role of the zinc finger protein ZBTB20 in regulating myocardial SERCA2a activity through PLN. We found that ZBTB20 is highly expressed in cardiomyocytes, and cardiac-specific ZBTB20 knockout mice showed significantly increased in vivo and ex vivo cardiac contractile function. In isolated cardiomyocytes, ZBTB20 knockout resulted in significant increases in contractility, SR Ca2+ content, and SERCA2a activity. Further investigations revealed that ZBTB20 deficiency led to a significant decrease in PLN expression, and replenishing PLN could reverse the hypercontractility of cardiomyocytes caused by ZBTB20 knockout. These results suggest ZBTB20 play a critical role in the regulation of cardiac Ca2+ cycling and contractility primarily through SERCA2a/PLN pathway.