Cardiac dysfunction is a well-known consequence of diabetes,with sustained hyperglycaemia leading to the development of a cardiomyopathy that is independent of cardiovascular disease or hypertension.Animal models of d...Cardiac dysfunction is a well-known consequence of diabetes,with sustained hyperglycaemia leading to the development of a cardiomyopathy that is independent of cardiovascular disease or hypertension.Animal models of diabetes are commonly used to study the pathophysiology of diabetic cardiomyopathy,with the hope that increased knowledge will lead ultimately to better therapeutic strategies being developed.At physiological temperature,left ventricular trabeculae isolated from the streptozotocin rat model of type 1 diabetes showed decreased stress and prolonged relaxation,but with no evidence that decreased contractility was a result of altered myocardial Ca2+handling.Although sarcoplasmic reticulum(SR)Ca2+reuptake appeared slower in diabetic trabeculae,it was offset by an increase in actionpotential duration,thereby maintaining SR Ca2+content and favouring increased contraction force.Frequency analysis of t-tubule distribution by confocal imaging of ventricular tissue labeled with wheat germ agglutinin or ryanodine receptor antibodies showed a reduced T-power for diabetic tissue,but the differences were minor in comparison to other models of heart failure.The contractile dysfunction appeared to be the result of disrupted F-actin in conjunction with the increased typeⅠcollagen,with decreased myofilament Ca2+sensitivity contributing to the slowed relaxation.展开更多
目的：探讨连接蛋白-2（JPH2）基因表达水平与二尖瓣疾病合并持续性房颤的关系以及分子机制。方法34例接受二尖瓣手术治疗的患者，根据术前心律分为两组：房颤组18例，为房颤心律患者；对照组16例，为窦性心律患者。所有二尖瓣手术均采...目的：探讨连接蛋白-2（JPH2）基因表达水平与二尖瓣疾病合并持续性房颤的关系以及分子机制。方法34例接受二尖瓣手术治疗的患者，根据术前心律分为两组：房颤组18例，为房颤心律患者；对照组16例，为窦性心律患者。所有二尖瓣手术均采用房间沟入路，取房间沟处左心房组织作心房组织样本。利用蛋白质免疫印迹（ Wester blot ）技术和实时定量逆转录聚合酶链反应（ RT-PCR）技术分别分析JPH2蛋白和mRNA的表达变化，分析miRNA-24在其中的作用。结果与对照组相比，房颤组左心房组织JPH2蛋白表达明显下降（0.94±0.29对1.53±0.61，P＜0.01）；两组JPH2基因mRNA表达水平差异无统计学意义（1.76±1.38对1.15±0.94，P＞0.05）。房颤组患者左心房组织miRNA-24表达显著升高（4.49±4.30对1.72±1.08，P＜0.05）。两组在性别、年龄、左心室射血分数以及心功能分级上并无差别，但房颤组患者左心房内径明显扩大（P＝0.02）。结论房颤时心房细胞JPH2蛋白表达水平明显下降，调控其表达的miRNA-24水平明显增加，这可能是房颤发病的分子机制之一，可致房颤心房重构及收缩功能受损。展开更多
The elementary Ca^2＋ release events, Ca2＋ sparks, has been found for a quarter of century. However, the molecular regulation of the spark generator, the ryanodine receptor （RyR） on the sarcoplasmic reticulum, rema...The elementary Ca^2＋ release events, Ca2＋ sparks, has been found for a quarter of century. However, the molecular regulation of the spark generator, the ryanodine receptor （RyR） on the sarcoplasmic reticulum, remains obscure. Although each subunit of the RyR homotetramer has a site for FKS06-binding protein （FKBP）, the role of FKBPs in modifying RyR Ca^2＋ sparks has been debated for long. One of the reasons behind the controversy is that most previous studies detect spontaneous sparks, where the mixture with out-of-focus events and local wavelets prevents an accurate characterization of Ca^2＋ sparks. In the pre- sent study, we detected Ca^2＋ sparks triggered by single L-type Ca^2＋ channels （LCCs） under loose-seal patch clamp conditions in FKS06-treated or FKBPI2.6 knockout cardiomyocytes. We found that FKBP dissociation both by FKS06 and by rapamycin decreased the Ca^2＋ spark amplitude in ventricular cardiomyocytes. This change was neither due to decreased releasable Ca^2＋ in the sarcoplasmic reticulum, nor explained by changed RyR sensitivity. Actually FKS06 increased the LCC-RyR coupling probability and curtailed the latency for an LCC to trigger a RyR Ca^2＋ spark. FKBP12.6 knockout had similar effects as FKS06/rapamycin treatment, indicating that the decreased spark amplitude was attributable to the dissociation of FKBP12.6 rather than FKBP12. We also explained how decreased amplitude of spontaneous sparks after FKBP dissociation sometimes appears to be increased or unchanged due to inappropriate data processing. Our results provided firm evidence that without the inter-RyR coordination by functional FKBP12.6, the RyR recruitment during a Ca^2＋ spark would be compromised despite the sensitization of individual RyRs.展开更多
基金Supported by The Health Research Council of New Zealand
文摘Cardiac dysfunction is a well-known consequence of diabetes,with sustained hyperglycaemia leading to the development of a cardiomyopathy that is independent of cardiovascular disease or hypertension.Animal models of diabetes are commonly used to study the pathophysiology of diabetic cardiomyopathy,with the hope that increased knowledge will lead ultimately to better therapeutic strategies being developed.At physiological temperature,left ventricular trabeculae isolated from the streptozotocin rat model of type 1 diabetes showed decreased stress and prolonged relaxation,but with no evidence that decreased contractility was a result of altered myocardial Ca2+handling.Although sarcoplasmic reticulum(SR)Ca2+reuptake appeared slower in diabetic trabeculae,it was offset by an increase in actionpotential duration,thereby maintaining SR Ca2+content and favouring increased contraction force.Frequency analysis of t-tubule distribution by confocal imaging of ventricular tissue labeled with wheat germ agglutinin or ryanodine receptor antibodies showed a reduced T-power for diabetic tissue,but the differences were minor in comparison to other models of heart failure.The contractile dysfunction appeared to be the result of disrupted F-actin in conjunction with the increased typeⅠcollagen,with decreased myofilament Ca2+sensitivity contributing to the slowed relaxation.
文摘目的：探讨连接蛋白-2（JPH2）基因表达水平与二尖瓣疾病合并持续性房颤的关系以及分子机制。方法34例接受二尖瓣手术治疗的患者，根据术前心律分为两组：房颤组18例，为房颤心律患者；对照组16例，为窦性心律患者。所有二尖瓣手术均采用房间沟入路，取房间沟处左心房组织作心房组织样本。利用蛋白质免疫印迹（ Wester blot ）技术和实时定量逆转录聚合酶链反应（ RT-PCR）技术分别分析JPH2蛋白和mRNA的表达变化，分析miRNA-24在其中的作用。结果与对照组相比，房颤组左心房组织JPH2蛋白表达明显下降（0.94±0.29对1.53±0.61，P＜0.01）；两组JPH2基因mRNA表达水平差异无统计学意义（1.76±1.38对1.15±0.94，P＞0.05）。房颤组患者左心房组织miRNA-24表达显著升高（4.49±4.30对1.72±1.08，P＜0.05）。两组在性别、年龄、左心室射血分数以及心功能分级上并无差别，但房颤组患者左心房内径明显扩大（P＝0.02）。结论房颤时心房细胞JPH2蛋白表达水平明显下降，调控其表达的miRNA-24水平明显增加，这可能是房颤发病的分子机制之一，可致房颤心房重构及收缩功能受损。
基金supported by the National Research and Development Program of China (2016YFA0500401)National Natural Science Foundation of China (31630035, 31571486, 81370203, 81461148026, 31271228 and 31327901)the Project of Beijing Municipal Science and Technology Commission (Z141100000214006)
文摘The elementary Ca^2＋ release events, Ca2＋ sparks, has been found for a quarter of century. However, the molecular regulation of the spark generator, the ryanodine receptor （RyR） on the sarcoplasmic reticulum, remains obscure. Although each subunit of the RyR homotetramer has a site for FKS06-binding protein （FKBP）, the role of FKBPs in modifying RyR Ca^2＋ sparks has been debated for long. One of the reasons behind the controversy is that most previous studies detect spontaneous sparks, where the mixture with out-of-focus events and local wavelets prevents an accurate characterization of Ca^2＋ sparks. In the pre- sent study, we detected Ca^2＋ sparks triggered by single L-type Ca^2＋ channels （LCCs） under loose-seal patch clamp conditions in FKS06-treated or FKBPI2.6 knockout cardiomyocytes. We found that FKBP dissociation both by FKS06 and by rapamycin decreased the Ca^2＋ spark amplitude in ventricular cardiomyocytes. This change was neither due to decreased releasable Ca^2＋ in the sarcoplasmic reticulum, nor explained by changed RyR sensitivity. Actually FKS06 increased the LCC-RyR coupling probability and curtailed the latency for an LCC to trigger a RyR Ca^2＋ spark. FKBP12.6 knockout had similar effects as FKS06/rapamycin treatment, indicating that the decreased spark amplitude was attributable to the dissociation of FKBP12.6 rather than FKBP12. We also explained how decreased amplitude of spontaneous sparks after FKBP dissociation sometimes appears to be increased or unchanged due to inappropriate data processing. Our results provided firm evidence that without the inter-RyR coordination by functional FKBP12.6, the RyR recruitment during a Ca^2＋ spark would be compromised despite the sensitization of individual RyRs.
