HYPERTHERMIA, HEAT SHOCK PROTEIN EXPRESSION & CARDIOPROTECTION

我们这个子项目的最初目标是识别 负责心脏保护的特定代谢成分 使用转基因鼠系的诱导型hsp70的功能。 我们的工作 在心脏和肝脏都产生了负面的结果，可能是由于 hsp70通过强制基因表达而适度升高。 后 完成两个手稿的进展中，我们计划把这个项目 暂停，直到具有更稳健基因表达的转基因模型被 available. 今年，我们重新集中精力研究 亚细胞能量区室化假说 储存在心肌中，使得ATP衍生的糖酵解支持 功能不同于由氧化衍生的ATP支持的功能。 我们正在利用一系列的转基因小鼠品系， 在靶向氧化能途径的基因表达中， 生产 这些细胞系包括肌红蛋白敲除， 过表达子和细胞色素c氧化酶（考克斯）亚基VIaH 击倒对手 我们已经完成了心肌性能的研究， 工作小鼠心脏的准备，并发现，令人惊讶的是， 肌红蛋白系没有明显的机械表型， COXVIaH敲除主要具有舒张功能障碍。 作为 COXVIaH基因敲除的结果是，考克斯活性降低， 柠檬酸合酶活性增加，而总ATP含量 似乎没有变化。 目前正在进行研究， 糖酵解和氧化磷酸化的相对贡献 ATP在这条生产线上 研究也在进行中，以评估 对心肌肌红蛋白表达改变的影响 代谢和对缺血的反应。 （协作2）报告 （1997年9月1日至1998年8月31日）

Our original goal for this subproject was the identification of the specific metabolic components responsible for the cardioprotection function of inducible hsp70 using a transgenic murine line. Our work in both heart and liver has yielded negative results, likely due to the modest elevation in hsp70 by forced gene expression. Upon completion of two manuscripts in progress, we plan to put this project on hold until a transgenic model with more robust gene expression is available. This year, we refocused our efforts to study the hypothesis that there is subcellular compartmentalization of energy stores in the myocardium such that ATP derived glycolytically supports functions different from those supported by ATP derived oxidatively. We are utilizing a series of transgenic murine lines with alterations in gene expression which target pathways in oxidative energy production. These lines include a myoglobin knock-out, a myoglobin over-expressor, and a cytochrome c oxidase (COX) subunit VIaH knock-out. We have completed studies of myocardial performance using the working mouse heart preparation and found, surprisingly, that the myoglobin lines have no distinguishing mechanical phenotype while the COXVIaH knock-out has predominantly diastolic dysfunction. As a consequence of COXVIaH gene knock-out, COX activity is reduced and citrate synthase activity is increased while overall ATP content appears unchanged. Studies are currently underway to establish relative contribution of glycolysis and oxidative phosphorylation to ATP production in this line. Studies are also underway to evaluate the effect on alterations in myoglobin expression on myocardial metabolism and the response to ischemia. (Collaborative 2) REPORT PERIOD: (09/01/97-08/31/98)