MAP Kinase and AKT Signaling in Congestive Heart Failure

描述(由申请人提供)：心肌肥厚和充血性心力衰竭是人类常见的疾病，可能是Akt/蛋白激酶B家族信号通路异常激活的结果。这项建议的主要目的是研究单个Akt家族成员在心肌细胞生长和代谢中的作用。虽然Akt1和Akt2高度同源并且在心肌细胞中的表达几乎相等，但我们假设Akt1选择性地调节生理性心肌细胞的生长，Akt2选择性地调节心肌细胞的葡萄糖代谢。初步数据显示，当胰岛素样生长因子-1(IGF-1)刺激培养的小鼠心肌细胞或注射生长激素-IGF-1时，可能需要Akt1，而不是Akt2，以响应生理性肥大的发生。此外，初步实验表明，Akt1不是压力超负荷诱导的心肌肥大所必需的，而Akt2是胰岛素刺激的心肌细胞摄取葡萄糖所必需的，而不是Akt1。在这项建议中，将评估Akt1、Akt2和AKT3在培养的新生大鼠和成年小鼠心肌细胞生长和存活中的相关功能。其次，将研究Akt1和Akt2在活体心脏生长和收缩功能中的作用。AKT‘’、AKT1+/~、AKTZ‘’、AKTZ‘’、AW2+/“和野生型小鼠目前在我们的小鼠群体中存在，它们将受到横主动脉收缩和游泳训练的压力超负荷。第三，Akt家族成员在心脏代谢调节中的作用将通过体外工作心脏分析和体内Awfa和AM2”A小鼠的微正电子发射断层扫描研究来验证。最后，将检测Akt2和PPARa以相互拮抗的方式调节心脏代谢的能力。我们的发现将有助于确定参与调控心肌细胞生长和代谢的特定信号机制。

DESCRIPTION (provided by applicant): Cardiac hypertrophy and congestive heart failure are common human ailments that may develop as a consequence of abnormal signaling pathway activation involving the Akt/Protein Kinase B family. The main aim of this proposal is to investigate the role of individual Akt family members in the growth and metabolism of cardiac myocytes. Although Akt1 and Akt2 are highly homologous and are expressed at near-equal amounts in cardiac myocytes, we hypothesize that Akt1 selectively regulates physiologic myocyte growth and that Akt2 selectively regulates myocyte glucose metabolism. Preliminary data shows that Akt1, but not Akt2, may be required for the development of physiologic hypertrophy in response to insulin-like growth factor 1 (IGF-1) stimulation of cultured cardiac myocytes or in response to growth hormone-IGF-1 infusion in mice. Furthermore, initial experiments suggest that Akt1 is not required for pressure overload-induced cardiac hypertrophy, and that Akt2, but not Akt1, is required for insulin-stimulated glucose uptake in cultured cardiac myocytes. In this proposal, the relative functions of Akt1, Akt2, and Akt3 in the growth and survival of cultured neonatal rat and adult murine cardiac myocytes will be evaluated. Second, the role of Akt1 and Akt2 in the growth and contractile function of the in vivo heart will be investigated. aktT'', akt1+/~, aktz'', aW2+/", and wild type mice, currently available in our mouse colony, will be subjected to pressure overload by transverse aortic constriction and to swimming exercise training. Third, the role of Akt family members in the regulation of cardiac metabolism will be examined by ex vivo working heart analysis and by in vivo micro-positron emission tomography studies of aWfA and aM2"A mice. Finally, the ability of Akt2 and Peroxisome-Proliferator Activated Receptor a (PPARa) to regulate cardiac metabolism in a mutually antagonistic manner will be examined. Our findings will help to identify specific signaling mechanisms involved in the regulation of cardiac myocyte growth and metabolism.