TRANSLATIONAL REGULATION OF CARDIAC PROTEIN SYNTHESIS

真核起始因子4 E（eIF-4 E）是 翻译起始，因此是调节 蛋白质合成的速率。该项目的重点是eIF的作用- 4 E在调节成人心肌蛋白质合成速率中的作用 细胞或心肌细胞。该项目的重要发现是：1）eIF- 4 E活性随着负荷的急剧增加而增加， 通过eIF-4 E磷酸化的程度和通过掺入 eIF-4 E转化为具有免疫活性的eIF-4F复合物，2）eIF-4 E 磷酸化依赖于活性张力的发展， 电刺激收缩的体外心脏细胞模型和电刺激收缩的体外心脏细胞模型。 急性压力超负荷体内模型，和3）eIF-4 E磷酸化， 心肌细胞与增加的翻译速率相关 启动和蛋白质合成的加速速率。的假设 这一延续建议的基础是，eIF-4 E活动是因果关系， 参与控制翻译效率，并且是主要的 负荷诱导的蛋白质合成速率加速的终点 成年心肌细胞该假设将通过使用 重组腺病毒作为基因转移野生型 或突变形式的eIF-4 E进入成年心肌细胞。利用这一战略， eIF-4 E表型将在活性和功能方面被操纵 并确定对翻译效率的影响。的能力 将测试增加负荷以加速蛋白质合成速率 在心肌细胞中表达非磷酸化的eIF-4 E突变体， 作为主动张力模型的电刺激收缩活动 发展具体目标如下：1）确定如何更改 在eIF-4 E的活性和功能影响翻译效率， 成体心肌细胞2)确定收缩引起的载荷是否加速 eIF-4 E活性特异性改变后的心肌细胞蛋白质合成 或功能。3)定义特定蛋白质激活之间的联系 激酶C亚型和eIF-4 E磷酸化，因为 eIF-4 E是蛋白激酶C的假定底物。因为增加的 eIF-4 E活性也与蛋白质合成速率加快有关。 在犬体内压力超负荷模型中合成，eIF-4 E是一种 潜在的重要终点，用于确定 调节蛋白质合成的速度在负荷诱导的肥大 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.