Effect of protein kinase C on cardiac hypertrophy

（改编自申请人的摘要）肥大是终末分化的心肌细胞对生长刺激的特征性反应。已经提出了在新生儿心肌细胞中主要定义的细胞内信号传导过程的级联来介导这种反应的特征，其中心组分是蛋白激酶C的活化。在以前的工作中，研究人员已经开发了一种新的转基因模型，该模型允许蛋白激酶C亚型在鼠心脏中的条件表达，并且他们已经确定该亚型的表达和激活足以影响不同的发育阶段特异性适应：PKC β在新生儿中的表达导致死亡，并与心肌细胞钙调节异常有关，而在成人中，转基因的表达与调节有关，而在成人中，转基因的表达与向心性心脏肥大、受损的机械性能和对局部缺血的相对抗性有关。在确认了这种方法的可行性之后，当前提案的重点是确定蛋白激酶C（β和β）的特定亚型的作用，并确定PKC的哪些特定靶点负责观察到的适应。功能的获得和丧失将在转基因模型中重现，并且PKC表达的功能效应的分析将在整个心脏的水平以及细胞水平上进行。将评估影响钙通量和肌丝钙敏感性的因素。该项目的一个独特之处是使用条件性转基因技术，可以评估心脏在不同发育阶段以及在改变其表型的过程中基因激活的生理和生化效应。这为研究因果关系提供了一个独特而强大的工具。

(Adapted from the Applicant's Abstract) Hypertrophy is a characteristic response of the terminally differentiated cardiac myocyte to growth stimuli. A cascade of intracellular signaling processes, largely defined in neonatal cardiocytes, has been proposed to mediated features of this response, a central component of which is activation of protein kinase C. In previous work, the investigators have developed a novel transgenic model which allows conditional expression of a protein kinase C isoform in the murine heart and they have established that expression and activation of the isoform is sufficient to effect distinct developmental stage specific adaptations: PKC Beta expression in neonates causes death and is associated with abnormal myocardiocyte calcium regulation whereas in adults, expression of the transgene is associated with regulation whereas in adults, expression of the transgene is associated with concentric cardiac hypertrophy, impaired mechanical performance and relative resistance to ischemia. Having confirmed the feasibility of this approach, the focus of the current proposal, the focus of the current proposal will be to identify roles for specific isoforms of protein kinase C (beta and epsilon) and to define which specific targets of PKC are responsible for the observed adaptations. Both gain and loss of function will be recapitulated in transgenic models and analysis of the functional effects of PKC expression will be at the level of the whole heart and also at the cellular level. Factors which influence calcium flux and myofilament calcium sensitivity will be evaluated. A unique feature of the project is the use of conditional transgenesis which allows assessment of the physiologic and the biochemical effects of gene activation in the heart at different developmental stages and while it os on the process of altering its phenotypes. This provides a unique and powerful tool to investigate causality.