MOLECULAR MECHANISMS OF CARDIAC DIFFERENTIATION

描述 (改编自申请人摘要)脑室终末分化 心肌细胞涉及谱系限制性基因和 永久性增长停滞。这种不可逆的组织特异性表达 基因和细胞周期退出排除了心肌再生的治疗作用 脑梗塞后的其他侮辱手法。对这一概念的理解 导致心脏分化的分子事件将提供一个强有力的 为未来操纵这些物质的目标奠定科学基础 人体心肌再生的因素。RB，一个典型的 Pocket蛋白家族，已被牵涉到指导关键方面 通过其与组织特异性转录的关联来研究这一过程 正向细胞周期调节因子与失活。一本小说和 识别和表征调解关键因素的富有成效的方法 在其他组织中的末端分化一直是为了利用E1a的能力 有选择地绑定和置换口袋里的内生因素 导致组织限制性基因下调，同时迫使细胞 周期重测。教官的实验室最近证明了 调控心脏特异转录的Pocket蛋白依赖途径 以及心肌细胞周期的调节。本申请 建议使用腺病毒E1a蛋白的口袋结合特性 和两种Rb缺乏症模型来研究口袋蛋白在 心脏终末分化。基于骨骼肌的结果 可以设想几种机制来解释口袋蛋白依赖 心脏基因的通路抑制。他们从基础上进行了具体的 这项提议的目的：1)E1a是否通过以下方式改变心脏因子的活性 直接结合和失活心源性因子，减少表达 或DNA结合，抑制转录活性，2)做心脏 转录因子，类似于MyoD，需要与Rb或 其他口袋蛋白的转录活性；3)是 E1a次于从RB释放E2F；4)E1a是否增加 Cyclin/CDK在心肌细胞中的活性；以及5)体内研究， Rb在心脏受限控制终末分化中的作用 同源重组。(摘要结束)

DESCRIPTION (Adapted from applicant's abstract) Terminal differentiation of ventricular myocytes involves the coordinate expression of lineage-restricted genes and permanent growth arrest. This irreversible expression of tissue-specific genes and cell cycle exit precludes myocardial regeneration as therapeutic maneuver after infarction of other insult. An understanding of the molecular events leading to cardiac differentiation would provide a strong scientific foundation towards the future objective of manipulation of these factors to regenerate human myocardium. Rb, the protypical member of a family of pocket proteins, has been implicated in directing critical aspects of this process through its association with tissue-specific transcription factors and inactivation of positive cell cycle regulators. One novel and fruitful approach to identify and characterize critical factors mediating terminal differentiation in other tissues has been to exploit E1A's ability to selectively bind and displace endogenous factors from the pocket resulting in downregulation of tissue-restricted genes while forcing cell cycle reetry. The preceptor's lab has recently demonstrated evidence for a pocket protein-dependent pathway that governs cardiac-specific transcription and cell cycle regulation in cardiac muscle. The present application proposes to exploit the pocket-binding properties of adenoviral E1A proteins and two models of Rb deficiency to study the role of pocket proteins in terminal cardiac differentiation. Based on results from skeletal muscle several mechanisms can be envisioned to explain the pocket protein-dependent pathway repression of cardiac genes. They from the basis for the specific aims of this proposal: 1) Does E1A alter activity of cardiogenic factors by directly binding and inactivating cardiogenic factors, decreasing expression or DNA binding, repressing transcriptional activity, 2) Do cardiac transcription factors, analogous to MyoD, require association with Rb or other pocket proteins for transcriptional activity; 3) Are the effects of E1A are secondary to release of E2F from the Rb; 4) Does E1A increase cyclin/Cdk activity in cardiac myocytes; and 5) Investigate in vivo, the role of Rb in controlling terminal differentiation by cardiac-restricted homologous recombination. (End of abstract)