Effect of protein kinase C on cardiac hypertrophy

肥大是终末分化的心肌细胞对生长刺激的一种特征反应。在以前的工作中，研究人员开发了一种新的转基因模型，允许在小鼠心脏中有条件地表达蛋白激酶C亚型，并且他们已经确定，蛋白激酶C亚型的表达和激活足以影响不同的发育阶段特异性适应：在新生儿中，PKCβ的表达导致死亡，并与心肌细胞钙调节异常有关，而在成年人中，转基因的表达与调节有关，而在成年人中，转基因的表达与向心性心肌肥大有关。机械性能和对缺血的相对抵抗力受损。在确认了这一方法的可行性后，也就是当前提案的重点，当前提案的重点将是确定蛋白激酶C的特定亚型(β和epsilon)的作用，并确定PKC的哪些特定靶点负责所观察到的适应。功能的获得和丧失将在转基因模型中概括，对PKC表达的功能影响的分析将在整个心脏水平上进行，也在细胞水平上进行。将评估影响钙通量和肌丝钙敏感性的因素。该项目的一个独特特点是使用了有条件的转基因，它可以评估心脏不同发育阶段基因激活的生理和生化影响，以及心脏表型改变的过程。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.