TRANSLATIONAL REGULATION OF CARDIAC PROTEIN SYNTHESIS

真核细胞启动因子4E(eIF-4E)对 翻译启动，因此是调节的关键机制 蛋白质合成的速度。本项目的重点是EIF的作用- 4E对成人心肌蛋白质合成速率的调节作用 细胞，或心肌细胞。该项目的重要发现是：1)EIF- 4E活性随着负荷的急剧增加而增加 通过eIF-4E的磷酸化程度和通过掺入 EIF-4E进入具有翻译活性的eIF-4F复合体，2)eIF-4E 磷酸化依赖于使用两者的主动张力的发展 一种电刺激收缩和AND的体外心肌细胞模型 急性压力超负荷的体内模型；3)eIF-4E的磷酸化。 心肌细胞与翻译率的增加有关 蛋白质合成的启动和加速。假说 这一延续提议的背后是eIF-4E的活动是因果关系 参与控制翻译效率，是主要的 负荷诱导的蛋白质合成速度加快的终点 成人的心肌细胞。这一假说将通过使用 重组腺病毒作为野生型或野生型基因转移的方法 或突变形式的eIF-4E进入成年心肌细胞。使用这一策略， EIF-4E的表型将根据活性和功能进行操纵 并确定了对翻译效率的影响。的能力 将测试增加负荷以加速蛋白质合成的速度 在心肌细胞中表达非磷酸化eIF-4E突变体 电刺激的收缩活动作为主动张力的模型 发展。具体目标如下：1)如何确定变更 在eIF-4E中，活动和功能影响翻译效率 成人心肌细胞。2)确定收缩引起的负荷是否加速 EIF-4E活性特异性改变后的心肌蛋白质合成 或功能。3)确定特定蛋白质的激活之间的联系 成年心肌细胞中的激酶C亚型和eIF-4E的磷酸化 EIF-4E可能是蛋白激酶C的底物，因为增加了 EIF-4E的活性也与蛋白质的加速速率有关 在犬体内压力超负荷模型中合成eIF-4E是一种 潜在的重要终点，用于确定 调节负荷性肥大过程中蛋白质合成的速度 在成人心肌中生长。

Eukaryotic initiation factor 4E (eIF-4E) is rate-limiting for translational initiation and therefore is a key mechanism for regulating the rate of protein synthesis. This project is focused on the role of eIF- 4E in regulating the rate of protein synthesis in the adult cardiac muscle cell, or cardiocyte. Important findings of this project were that 1) eIF- 4E activity was increased in response to an acute increase in load is measured by the extent of eIF-4E phosphorylation and by incorporation of eIF-4E into the translationally activity eIF-4F complex, 2) eIF-4E phosphorylation was dependent upon active tension development using both an in vitro cardiocyte model of electrically stimulated contraction and an in vivo model of acute pressure overload, and 3) eIF-4E phosphorylation in the cardiocyte correlated with an increased rate of translational initiation and an accelerated rate of protein synthesis. The hypothesis underlying this continuation proposal is that eIF-4E activity is causally involved in controlling translational efficiency, and is a primary endpoint for load-induced acceleration of the rate of protein synthesis in the adult cardiocyte. The hypothesis will be tested by employing recombinant adenoviruses as a method for gene transfer of either wild-type or mutated forms of eIF-4E into adult cardiocytes. Using this strategy, the eIF-4E phenotype will be manipulated in terms of activity and function and the effects on translational efficiency determined. The ability of increased load to accelerate the rate of protein synthesis will be tested in cardiocytes by expressing a non-phosphorylatable eIF-4E mutant using electrically stimulated contractile activity as a model of active tension development. The specific aims are as follows 1) Determine how alterations in eIF-4E activity and function affect translational efficiency in the adult cardiocyte. 2) Determine if contraction-induced load accelerates cardiocyte protein synthesis after specific alterations in eIF-4E activity or function. 3) Define linkage between activation of specific protein kinase C isoforms and eIF-4E phosphorylation in adult cardiocytes, since eIF-4E is a putative substrate for protein kinase C. Because increased eIF-4E activity was also linked to an accelerated rate of protein synthesis in a canine model of pressure overload in vivo, eIF-4E is a potentially important endpoint for determining the mechanisms that regulate the rate of protein synthesis during load-induced hypertrophic growth in the adult myocardium.